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THE ENERGY APPROPRIATE PERSONAL COMMUTER VEHICLE

The Sembilanagon

Mark Cimarolli

Muhammad Fahmi Ibrahim Alicia Janszen

Christopher Keegan Benjamin Kortz Jeremy Lewis

Richard Walton Jason West

Robert Workman

May 31, 2007 Abstract In the current climate of high-energy prices and impending shortages of fossil fuels, the nature of transportation in the United States and around the world will need to change drastically in the coming years. This situation has created the need for a lightweight alternatively fueled personal vehicle to replace larger energy-wasting automobiles for short distance trips. Several web-based surveys, interviews of students on campus, and observations about parking situations were used to create a specific set of customer needs and design specifications. The design specifications for these personal commuter vehicles were further refined through extensive benchmarking and patent research of similar products on the market. A three-wheeled recumbent style vehicle with human and electric power integration was created to address this need.

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Table of Contents

1.0 Introduction____________________________________________ 4

1.1 Initial Problem Statement _________________________________________ 5

2.0 Customer Needs Assessment ______________________________ 5

2.1 Weighting of Customer Needs _____________________________________ 6

3.0 Revised Needs Statement and Target Specifications ___________ 8

4.0 External Search ________________________________________ 10

4.1 Benchmarking_________________________________________________ 10

5.0 Concept Generation ____________________________________ 12

5.1 Problem Clarification ___________________________________________ 12

5.2 Improving Creativity____________________________________________ 13

5.3 Concept Generation ____________________________________________ 15

6.0 Concept Selection ______________________________________ 24

6.1 Data Analysis and Calculations for Feasibility and Effectiveness Analysis _ 24

6.2 Concept Screening _____________________________________________ 29

6.3 Concept Development, Scoring and Selection ________________________ 30

7.0 Final Design Refinement_________________________________ 34

7.1 Initial Problem Statement ________________________________________ 64

7.2 How does it Work ______________________________________________ 66

7.3 How is it Made ________________________________________________ 71

8.0 Conclusion ____________________________________________ 79

Appendix A: Interview Guide _________________________________ 83

Appendix B: Second Interview Questions________________________ 85

Appendix C: Business Opportunity_____________________________ 86

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Appendix D: Design for Manufacturability and Assembly __________ 88

Appendix E: Failure Modes and Effects Analysis ________________ 118

Appendix F: Cost Estimation _________________________________ 121

References ________________________________________________ 128

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1.0 Introduction The use of the world’s natural resources is becoming more of a concern every day. Nations have consumed coal and oil for too long without any concern for the environment and conservation. Today, America alone consumes 20 million barrels of oil per day at a cost of six billion dollars per week.1 At this rate, the earth’s supply of these natural resources is in serious jeopardy. Furthermore, the average cost of crude oil has increased from $8.03 per barrel in 19981 to more than $70.00 a barrel at times in 2006. Already the effects of dwindling energy reserves are affecting American consumers as can be seen from the rise in gas prices and resulting effect on the costs of consumer goods and services. It is now time for the government and private sector to turn to new means of energy production and efficiency in order to prevent unmanageable energy costs and unnecessary environmental damages.

In May of 2001, President Bush created the National Energy Policy Development Group (NEPD). The goal of the group was to “develop a national energy policy designed to help the private sector, and, as necessary and appropriate, state and local governments, promote dependable, affordable and environmentally sound production and distribution of energy for the future.”1 The NEPD identifies new technologies and potential sources of cleaner, more efficient, and more abundant sources of energy. Such sources include solar, geothermal, wind, hydrogen, and biomass. Although hydrogen and biomass appear to be promising resources for the future, there is no current infrastructure to support these methods.

Though the energy crisis applies to all forms of consumption, the transportation sector accounts for about two-thirds of the oil consumption of the world.1 In addition to an expected increase of approximately 30% in transportation oil consumption over the next 20 years, our capability to produce oil is dwindling. America’s refining capacities have been stagnant for the last thirty years.2 The United States produces 39% less oil today than it did in 19702, despite nearly tripling its consumption. This has lead to a dependence upon foreign sources of oil, and due to international industrialization, foreign oil has become increasingly sought after by developing nations. To solve these transportation-specific issues, the Department of Energy has decided to focus on increasing domestic productivity, reducing waste, trimming costs, and seeking out alternative energy sources.

It is for these transportation related reasons that this senior design project focuses on creating an energy efficient, cost effective vehicle that can aid in reducing the amount of fuel used on short range trips. Furthermore, Team 6 has decided to focus the product on a consumer who regularly makes short trips, such as students on college campuses and business people that make short commutes. Providing these individuals with an alternative to inefficient automobiles and high transportation costs, a one passenger energy efficient vehicle is a highly marketable energy appropriate solution.

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1.1 Initial Problem Statement The comprehensive need for this year’s senior design class is to address the problems surrounding today’s energy usage, with a focus on transportation vehicles. Six teams were given the opportunity to devise a needs statement based upon this general topic. After completion of initial research, two types of vehicle projects were chosen. The first vehicle addresses similar needs identified by the senior design class of 2005-2006, which were developing energy efficient personal campus transport vehicles. The second vehicle is an energy efficient water craft. From these two topics, the professors refined the presented problem statements. The following is the refined needs statement for the land based vehicle projects:

Energy-appropriate 2 passenger "parking efficient" all-season community vehicle: “There is a need for a compact 2-passenger vehicle powered by alternative energy that will be marketable for intra-campus and intra-community travel. The vehicle must address the problems of pollution, oil dependency, oil consumption, parking, and money spent on gas. It must be high-quality, safe, aesthetically appealing, weatherproof and capable of being used all year.”3

2.0 Customer Needs Assessment The customer needs assessment was the tool utilized to identify the aspects of the product that will make it marketable and valuable to the user. This process allows the engineer to focus initially on the general attributes of the product that will determine its success on the market. Later in the design process these initial customer needs can be translated into the design specifications that will govern the manufacturing and improvement of the project. Customer needs were evaluated by live interviews and online surveys. The interviewees and those surveyed were asked the same questions so that a large amount of information was available for comparison. Three specific groups of perspective customers were targeted: college campus occupants, small city residents, and suburban residents with short commutes. A total of ninety-one surveys were conducted; the survey is attached in Appendix A. One of the most beneficial questions asked involved the storage needed on the vehicle. Most participants said they would be carrying a backpack, laptop, or groceries. It was estimated these would not exceed thirty pounds. Customers also showed interest in maintaining a clean environment, which led to the conclusion that an alternatively fueled vehicle would be desirable. It was also demonstrated that human power was something they would be willing to use and that the aesthetics of the vehicle were important. Observations were conducted on parking around campus and an assessment of items potential customers carry with them. After conducting the interviews the information was compiled and customer needs were established as seen in Figure 1.

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Storage Durable Aesthetically Pleasing Light Performance Efficiency Safe Easy to Operate Reliability Human Power Cost under $1,500 Collapsible Portable Marketability Able to fit through a standard doorway Environmentally Friendly Figure 1: Initial Customer Needs List

Obtained from Interviews and Observations After discussing the initial customer needs, an additional short survey was conducted to answer some new questions that addressed additional customer desires; these survey questions can be found in Appendix B. The results demonstrated that this vehicle is feasible in the lifestyles of about half of the participants surveyed. Since no one surveyed owned a moped, the survey asked why they did not own this type of vehicle. The majority responded that it was because of the price with other important factors being convenience and storage. It was also expressed by the participants that weather protection was of interest in this type of vehicle. The additional surveys confirmed customer views found in earlier surveys; therefore the survey did not require changes be made to Figure 1. 2.1 Weighting of Customer Needs After conducting interviews, the team decided what was important to potential customers. Weighting customer needs is important and helps focus future progress on the customer input. Team 6 chose to use the analytical hierarchy process (AHP) approach to weigh the overall categories. The AHP style is a standard method used to rank categories of information against one another. This process is valuable because it allows comparison between qualitative and quantitative aspects of a decision, reducing them to a one-on-one comparison before synthesizing. 4 The AHP process allowed for the quantitative comparison of marketability, portability, efficiency and performance with one another to evaluate the customer needs and show their level of importance compared to one another. The weighted customer needs are represented below in Table 1 to show a hierarchy of customer needs. In Table 1, boxes of the matrix with a number one in them represent two customer needs that are of equal importance to the customer. A box that has a number greater than one in it means that the aspect in the top row is of greater importance than

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the aspect in the left hand column. Similarly, a box that has a number less than one in it means that the aspect in the top row is of less importance than the aspect in the left hand column.

Table 1: AHP Comparison Chart to Determine Weighting for Main Objective

Categories Portable Efficiency Performance Marketability Portable 1.00 0.33 0.20 3.00 Efficiency 3.00 1.00 0.33 3.00 Performance 5.00 3.00 1.00 5.00 Marketability 0.33 0.33 0.20 1.00 Total 9.33 4.67 1.73 12.00 Weight 33.7% 16.8% 6.3% 43.3%

Figure 2 shows the importance of four general categories of customer requirements as collected via the team’s survey of campus students, professors, and business men and women. These particular groups were surveyed in order to get information from a wider perspective of possible customers than just students and friends at Ohio University. Figure 2 was created using the survey in conjunction with the matrix shown in Table 1. The importance ratings for Figure 2 and Table 1 were determined from customer feedback and team views. The customer results indicate the importance of marketability. Even though marketability was important to the customer, performance and reliability will also be concentrated on heavily. The project will also focus on efficiency and energy consumption.

1. Portable (0.34) 1.1 Lightweight F.1 Collapsible C.1 Able to fit through a standard doorway 2. Efficiency (0.17) 2.1 Environmentally Friendly 3. Performance (0.06) 3.1 Safe 3.2 Reliability C.2 Human Power 3.3 Durable 3.4 Meets speed, acceleration, and cornering requirements. 4. Marketability (0.43) 4.1 Aesthetically Pleasing 4.2 Easy to Operate 4.3 Storage C.3 Cost under $1,500

Figure 2: Hierarchal Customer Needs List (Weighting Factors)

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With the results obtained through customer interaction, Team 6 has adequate information to move forward with the design for the time being; however, further customer feedback will be collected later on a per-need basis. 3.0 Revised Needs Statement and Target Specifications The project needs statement undergoes changes and revisions as the group researches benchmarking information and collects information from the potential customer base. Crucial aspects of the original needs statement were identified and refined to fit the needs of perspective customers. Some of the refinements include a design that will address the issue of parking, and the incorporation of human powered assistance that will address the issue of reliability. The following is the revised problem needs statement:

Energy-appropriate 1 passenger compact vehicle for moderate weather conditions: There is a need for a compact single passenger vehicle powered by alternative energy that will be marketable for intra-campus and intra-community travel. The vehicle must address the problems of pollution, oil dependency, oil consumption, parking, and fuel costs. The vehicle also needs to address storage capabilities. It must be high quality, safe, aesthetically appealing, and reliable.

In addition to the proposed needs statement, extensive customer interviewing and surveying was done in order to develop a list of viable customer needs and the target specifications necessary in the vehicle in order to properly meet as many of those needs as possible. Table 2, shown below, is a composition of the specific needs for this vehicle and the relative importance of each of those needs; the importance is shown with five being the most important and one being the least important. Although the customer interviews were necessary initially to compose this list, the target specifications were further refined through benchmarking research and feasibility evaluation. The relative importance of each of these specifications was determined mainly using survey results, research, and a specification meeting with Dr. Kremer and the other team working on a similar project in order to reach a group consensus.

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Table 2: Target Specifications based on Customer Needs # Need Imp 1 The Vehicle Is capable of traveling at speeds of 30 miles per hour 5 2 The Vehicle Will cost no more than $1500 manufacturing 5 3 The Vehicle Is capable of carrying 250lb person 4 4 The Vehicle Will weigh no more than 100lb 3 5 The Vehicle Is capable of traveling 20 miles between fueling/charging 5 6 The Vehicle Will have a security device 3 7 The Vehicle Is capable of carrying 30lb additional payload in a 12x18x6”

space 4

8 The Vehicle Will fit through a standard American doorway of 30” 4 9 The Vehicle Will include functional side view mirrors 5 10 The Vehicle Will include a headlight, tail-light, turn signals, and

reflectors 5

11 The Vehicle Will have 10” of clearance between pedals and ground 1 12 The Vehicle Fully loaded, will travel up a 5% grade at 10 mph 2 13 The Vehicle must be stable in a turn radius of 15 feet at 10 mph 3 14 The Vehicle Will be aesthetically pleasing 3 15 The Vehicle Will stop from 25 mph speed within 30 feet 4 16 The Vehicle Will be easily stored 2 17 The Vehicle Will have adequate suspension 1 18 The Vehicle Will have a functional horn 2 19 The Vehicle Will be environmentally friendly 5 20 The Vehicle Will accelerate from 0-25 mph in no more than 7 seconds 4 21 The Vehicle Will be small enough to fit two in one parking space side-by-

side. 3

22 The Vehicle Will be able to fully charge in no more than 8 hours. 4 Values for the targets specifications came from multiple sources and decision-making processes. The top speed requirement came from a national regulation which states that any vehicle must not travel more than 30 miles per hour to be considered a moped. If classified as a moped, this vehicle would not have to be registered and a license would not be needed for operation. The ground clearance was determined by measuring the depths and the heights of a number of potholes and speed bumps, respectively. Also, through measurement of a standard size mountain bike, the ground clearance was determined to be 10 inches from the pedal. The requirement for the stopping distance come s for the U.S. Consumer Product Safety Commission which states a bicycle must stop in 15 feet traveling 15 mph on level ground.5 As this relationship is nonlinear, an increase of velocity to 25 mph requires at least 30 feet stopping distance. According to the AFCEE, an 18 foot turning radius is ideal and a 15 foot turning radius is a “comfortable minimum” at 10 mph. 6 Specifications such as range, price, weight, acceleration, and cargo capacity came from benchmarking. (See Table 3: Benchmarking of Products)

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4.0 External Search After the completion of a patent search for electric vehicles, there were primarily three patents that are pertinent to this project. Each of these patents contained a bicycle with an electric motor as a power source. In addition to patent research, benchmarking was also conducted. One of the patents found (“Electric Bicycle”, US Patent no. 6,629,5747) consisted of a bicycle assembly with a lightweight DC electric motor. The DC electric motor is used to replace the human pedaling acting to propel the bicycle. This bicycle consists of two large rechargeable batteries that power the DC motor. These batteries are primarily charged by a standard 110 Volt AC outlet. However, the bicycle consists of two other devises that are adapted to recharge the batteries while in use. The first is a regenerating wheel rotor assembly mounted on the front wheel, and the second is a solar panel mounted on the front wheel fender. Another patent that was found that is pertinent to this project (“Electrical Bicycle”, US Patent no. 5,433,2848) consisted of a bicycle assembly with a DC motor. In this patent, the DC motor is attached to the left side frame of the bicycle and supplies power to the rear wheel hub forming a one-piece unit with the hub. The hub assembly is designed so that the bicycle may also be powered by a human pedaling action either in parallel with the DC electric motor, or as an independent power source. This patent did not specify any method for recharging the batteries. The last patent found that is pertinent to this project (“Electric Bicycle and Methods”, US Patent no. 6,629,5749) consisted of a bicycle assembly with a DC motor. The DC motor is confined within the pedal assembly. This assembly contains a complex clutch and gearing system to allow exclusively a pedaling action, exclusively the DC motor operation, or a combination of both methods of propelling the bicycle. Again, this patent does not specify any method of recharging the batteries. From the patent research, it was found that ideas already exist for an electric bicycle. However, these patents do not address the issue of storage, compactability, or any weather protection. The basic patent ideas can be used as a foundation to meet the customers’ needs. By incorporating these ideas along with a frame modification, a new and unique electric vehicle concept will be established. 4.1 Benchmarking The benchmarking section covers concepts already in production that address the needs specified in the team’s needs statement. The designs below are examples of manufactured products. However, of these designs, none of them address all of the specifications in the team’s needs statement. With these benchmarked products, the scope of the project becomes clearer from a feasibility standpoint.

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Figure 3: Machine X10 Figure 4: WE815 Folding E-Bike11 Machine X8, shown in Figure 3, manufactured and sold by Electric Cyclery, is a two-wheel, off-road capable electric bike with assisted pedaling. Machine X is capable of going up a thirty percent grade unassisted while carrying a 250-pound adult. This vehicle could be made more efficient since it does not have any regenerative capabilities. It is also quite expensive. The WE815 Folding E-Bike9, shown in Figure 4, is a lightweight, foldable moped, which makes it easy to store and park. This vehicle has good acceleration and is relatively inexpensive, however, the top speed is unimpressive and the power output is significantly less than most of the vehicles that were researched.

Figure 5: e-Go Cycle LX12 Figure 6: EZ - 3 SX13 The e-Go Cycle LX12, shown in Figure 5, is a two-wheel commuter vehicle manufactured and sold by eGo Vehicles, Inc. North America. It is powered by an electric motor and has two engine settings: “Go Fast” and “Go Far”. The “Go Far” option only allows the rider to travel at about 75% of the “Go Fast” speed, but allows for more distance to be covered overall. It is fully equipped with the requirements for a street legal moped (head light, tail light, two mirrors and turn signals), and is also equipped with a trailer hitch to attach a small carrier for extra cargo. The EZ-3 SX13, shown in Figure 6, is a recumbent tricycle manufactured by JV Bike Sales and Rentals Ltd. The bike has the streamline advantages that a recumbent bike design offers with an electric motor assist option. This product does not offer options to make it street legal. However, the added stability of a third wheel may help some prospective buyers to be more confident with the recumbent style. To compare these products, Table 3 was created. The capabilities of each benchmark are

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listed in key categories such as cost, range, top speed, and capacity, as well as other features. The purpose of Table 3 is to gain an understanding of what is feasible based on these benchmarks.

Table 3: Benchmarking of Products Feature Machine X WE815 E-Bike e-Go Cycle LX EZ3 - SX

Weight 55 lbs 50 lbs 132 lbs 90 lbs Cost $4,200.00 $499.00 $1499.00 $1950.00 Range 15 – 25 miles 20 miles 25 miles 25 miles Reliability Pedals Pedals Only Electric Pedals Top Speed 20-35 mph 16 mph 24 mph 12 mph Power Output 500 W 200 W 4800 W max 3600 W Voltage Input 36 V 24 V 24 V 36 V Capacity 250 lbs 300 lbs 350 lbs. Not available 5.0 Concept Generation 5.1 Problem Clarification Effective brainstorming requires clear objectives and guidelines. Without these, brainstorming can be a waste of time, and will create frustration within a group. Concept mapping is an effective technique to define objectives and guidelines. Figure 7 gathers ideas from customer surveys and the refined needs statement, and combines them into one simple diagram. The diagram was used as a guideline during brainstorming sessions. In the diagram, three main sub-groups are established – drive train, structure, and marketability – as they are distinctive from each other yet cover all aspects of the product.

Figure 7: Product Design Subsystems

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The drive train sub-group is focusing on the internal mechanics of the vehicle. Team members researched alternative power sources, engine types and power trains that satisfy the needs statement of this project: efficient, safe, and environmental friendly. The structure sub-group focuses on the vehicle’s physical design, for example: seat placement, wheel design and body structure. This involves creativity and imagination from each team member and research on proven technologies. The marketability sub-group deals with the vehicle’s business opportunity shown in Appendix C. Team members should take into account customer needs and research the current market for attractive features that might add personality and flair to the vehicle. 5.2 Improving Creativity There are several ways to develop new ideas, including benchmarking and creative thinking. The benchmarking process generally includes surveying the market for current products and analyzing each of their strengths that can be implemented in the design, and their weaknesses that need to be avoided. The idea of creative thinking is trying to open team members’ eyes to many possibilities of achieving an objective using various techniques. Conventional Techniques Creative thinking is a process of brainstorming in which various techniques are used to facilitate the generation of ideas. Techniques include the use of storyboard, morphological analysis, attribute listing, and mind mapping. Methodical creative thinking techniques are needed so that ideas can be grouped logically and practical discussion can be completed based on the ideas. The team selected several creative thinking techniques that are suitable for this project including: sketching, spider diagrams, tables, observation, and experimentation. Sketching Sketching is a technique where ideas are drawn on paper, and basic explanations are given on each of the drawings. This technique is usually applied to conceptual drawings, for example the structure of a car, mechanical components and manufacturing processes. By sketching ideas, not only can team members see their overall design from many perspectives so improvement can be made later; it also helps other members to further understand their conceptual design and contributes some ideas toward it.

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Figure 8: Sketch Example

Spider Diagram The idea of a spider diagram is to group different thoughts into a simple yet understandable diagram. This can be achieved by grouping each idea into a sub-topic which also can be grouped into a more generalized sub-topic as seen in Figure 9. This technique is ideal for brainstorming non-conceptual details that need elaboration.

Figure 9: Spider Diagram

Tables Using tables is another creative thinking technique that emphasizes data listing and comparison. Unlike the spider diagram, a table is meant to compare two or more ideas side-by-side. The details of each idea are listed in the table and divided into their own elements for an easier interpretation. This can be used to compare each idea element-by-element so that better conclusions can be made. As shown in Table 4, various benchmarked products and their features could be compared easily by the use of a table.

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This allowed the team to compare features of different available products and evaluate the feasibility of each one.

Table 4: Benchmarking of Products (from Section 4.1) Feature Machine X WE815 E-Bike e-Go Cycle LX EZ3 - SX

Weight 55 lbs 50 lbs 132 lbs 90 lbs Cost $4,200.00 $499.00 $1499.00 $1950.00 Range 15 – 25 miles 20 miles 25 miles 25 miles Reliability Pedals Pedals Only Electric Pedals Top Speed 20-35 mph 16 mph 24 mph 12 mph Power Output 500 W 200 W 4800 W max 3600 W Voltage Input 36 V 24 V 24 V 36 V Capacity 250 lbs 300 lbs 350 lbs. Not available Observation Observation of real-world situations is a good way to stimulate the mind. However, it also must be coupled with analysis and problem solving skills in order to maximize the creative thinking. For example, team members observed the local parking situation and the items individuals carried on routine trips around campus. Experimentation A hands on or active approach to creative thinking can bring success when other methods have become stale or failed to produce new ideas. In this case, the act of riding a recumbent bicycle led to discussion of the possibility of a three wheeled design to better accommodate the requirement of stability with a loaded vehicle. This method was also used when deciding to incorporate lean steering. A mock up was assembled to demonstrate the lean steering capabilities and the feasibility of this idea. 5.3 Concept Generation Main Configuration A fundamental decision in this vehicle’s design process was to determine the number of wheels it would have. It was decided that four-wheeled designs could not achieve the overall goal established in the needs statement, because they take up more room and thus more parking area. They are also heavier than two and three wheeled designs, which is important because the weight of the vehicle dictates the amount of energy necessary for operation in this vehicle’s specified speed range. Further analysis, as shown in Figure 10, demonstrated that two and three wheel designs provide an ideal combination of stability, size, and efficiency for a single passenger vehicle. Furthermore, these two and three wheel designs offer two seat configurations – recumbent and upright. Each configuration has advantages and disadvantages. Figure 10 is a comparison of advantages and disadvantages for the possible configurations.

Advantages Recumbent Upright Two wheels + higher efficiency

+ comfortable + most compact size + customer familiarity

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- longer than upright configuration - less stable - less customer familiarity

- low efficiency - less comfortable - less stable

Three Wheels + best stability + higher efficiency + comfortable - largest size - less customer familiarity

+ better stability + customer familiarity - wider wheel base - low efficiency - less comfortable

Figure 10: Vehicle Configuration Decision Matrix

Power Most commercial vehicles on the market right now are non-hybrid vehicles, meaning that they utilize only one energy source, whereas a hybrid vehicle uses multiple energy sources. For example, a typical automobile with an internal combustion engine fueled by gasoline is considered a non-hybrid vehicle. Although there are many forms of alternative energy available, finding a single energy source that provides enough power and has the required infrastructure to replace gasoline as the world’s transportation energy is quite difficult. Table 5 provides basic information about some alternative energy sources, including their pros and cons.

Table 5: Alternative Energy Choices

Energy Source Overview Pros Cons Fossil Fuels (Internal Combustion Engine)

Fuel is ignited in the engine chamber and creates gas expansion to turn the pistons.

- Proven technology - Alternative fuel is easy to find

- low efficiency - complicated technology

Electric (battery-powered)

Electricity is supplied from battery to magnet in the motor to rotate the rotor.

- very efficient - quiet operation

- powerful motors are expensive and heavy - limited range of efficient operation

Solar power Solar power is collected and turned into electricity to generate motor.

- abundant energy source - clean technology

- requires large solar cells to produce enough power

Fuel cells Oxygen and hydrogen are accepted at both electrodes to produce electricity

- abundant energy source - clean technology

- very expensive technology - no infrastructure - energy storage issues

There are two basic types of hybrid vehicles: series and parallel. In a series design, the internal combustion engine generates electric power, which is stored in batteries to power an electric motor. In parallel designs, both an electric motor and an internal combustion

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engine are connected to the drive train.14 In other words, the internal combustion engine is used directly for providing mechanical power rather than for generating electricity. Most major automobile manufacturers have some type of hybrid vehicle either on the market or in the design phase. Some of the more notable current hybrid vehicles include the electric-petroleum engines developed by Toyota and General Motors. Although these car manufacturers use the same basic idea of combining the electric motor and internal combustion engine to improve efficiency, the implementations can be completely different. For example, one of Toyota’s hybrids uses two different motors to power the drive train. It uses an electric motor in low and cruising speeds, and the fuel engine engages to provide more torque in heavy acceleration15. General Motors has a hybrid vehicle that uses the electric motor to assist the main petroleum-based engine by taking some of the engine power load. At first glance these two technologies seem to be beyond the scope of this project because of the complicated technology; however, this research provides a good foundation for basic understanding of the hybrid technology for the team to research on more viable hybrid alternatives. Human Assisted Power It is not possible for human power to match an electric motor or fuel engine in terms of power output or torque for any extended length of time. However, the idea of incorporating an element of human assisted power to the drive train is one that is very attractive in terms of increasing efficiency and assuring reliability. Human power can be used to supplement an electric motor in situations where more torque is needed. Instances of fast acceleration or climbing a large percent grade are examples of when the two power sources can work together. This is quite similar to the concepts being used in most hybrid automobiles on the market today, although this vehicle’s two energy sources are an electric motor and human power, rather than an internal combustion engine and an electric motor. Another advantage human assisted power offers is added reliability in a case where the batteries need to be recharged or the motor malfunctions. Instead of the operator being stranded, he or she is still able to pedal to the destination. Solar Cell/Battery Power Batteries and solar cells are two sources that can be used very efficiently to power electric motors. Combining the two can extend the versatility of a solar vehicle into low light conditions. In normal daylight, the electric motor can use power from the solar cells, but when it is dark outside the batteries may act as the primary energy source for the electric motor. Although this may seem attractive, the size of the solar cells and complicated nature of integrating both power sources make this solution unfeasible for the scope of this project. Hybrid Fossil Fuel/Electric Although gas/electric hybrid technology has been used with relative success by the auto industry, cost and weight issues make this approach prohibitive for the project at hand. The focus here is on efficiency through weight savings and smart use of technology. Another aspect that makes this infeasible is space, which is to be kept to a minimum to address the parking issue. Finally the overall goal of this project is to reduce the

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dependence on fossil fuel and this technology is inseparable from that energy source. Research on this technology was done in order to explore all options available and inspire new ideas within the group. Safety Safety is clearly a very important factor in any vehicle design. In designing a small vehicle for use on local roadways, one of the paramount safety concerns that must be considered is that of visibility. Oftentimes motorcyclists try to ride together in order to increase their visibility to other drivers in automobiles and even pedestrians. The vehicle that is being proposed in this project will be even smaller and less visible than a typical motorcycle. Therefore, quite a bit of brainstorming was done amongst the team members in order to develop some creative ways to address this and other safety concerns. Figure 11 includes some of the major ideas that were suggested to deal with the safety issue.

Safety

Sturdy materials

Reflector

Lights

Horns

Front & back

Turn signal

backseat

Flag

pedal

Helmets

Figure 11: Safety Spider Diagram

Marketability Although with high efficiency, a radical body design, and safety features implemented in the final design, a product cannot be successful without taking into account customer needs. It is not feasible to take into account all of the suggestions from customers, but these little touches add flair to the design and will be major deciding factors for certain buyers. Team member’s researched products currently on the market and analyzed customer needs in order to come up with marketable features [See Sections 2.1 and 2.2]. Figure 12 provides some of the ideas that can be used in the final design as selling points for this vehicle.

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Figure 12: Marketability Spider Diagram

Collapsibility In the customer survey, collapsibility was highly rated as a desirable feature for this vehicle. Some form of collapsibility allows the bike to be transported and stored easier. Different ideas were proposed amongst the team members as to how to implement some form of collapsibility in the design of this vehicle. Ideas ranging from simply being able to fold the handle bars down towards the seat to make the vehicle shorter, to placing a pivot joint near the center of the bike that would allow it to be folded to half of its initial length were all suggested and became part of some of the conceptual designs. Comfort A cushioned seat with a high back and shock absorbers will definitely give the user a much smoother and more comfortable ride. This aspect is almost always overlooked in current bicycle designs, which would make this another sellable feature of this vehicle. Furthermore, an adjustable seat can be useful to ensure that riders of all heights will be able to reach the pedals. Storage In order to satisfy customer needs, various storage sizes and dimensions must be implemented in the final design. It should be noted that most customers plan to use the vehicle’s storage for items such as grocery bags, laptops, and backpacks. In many instances, most notably for laptop storage, the customer might need to secure his or her belongings, which means that some or all of the storage on this vehicle should be lockable and weather protected.

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Accessories Some of the accessories that were suggested by the team using customer responses as well as benchmarking can be seen in Figure 12. Although these accessories can be used to increase the marketability of the vehicle for certain customers, extensive amounts of accessories will also increase the price of the vehicle considerably. Initial Concept Sketches The following figures illustrate the initial conceptual designs produced by the members of Team 6. Many positive attributes were included among the sketches. These attributes were combined in later stages to produce more sophisticated concepts which would be better able to meet customer needs and the overall goals of the team. This process is discussed in greater detail in sections 6.2 and 6.3. Figure 13, is representing a storage idea that fits snuggly over the rear tire. This allows for extra storage around the tire that would be lost if the storage was only on top of the tire. This can be seen implemented into a design idea such as the design in Figure 14. Another important idea from Figure 13 is the use of hinged clips; the clips secure small items and bags so they are stable in the compartment.

Figure 13: Over the Wheel Storage Idea

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Figure 14: Integration of Rear Storage

Figure 15 and Figure 16 show two different designs. Figure 15 shows a scooter like design that has removable pedals and a collapsible handle bar feature. Figure 16 models a recumbent design with two wheels either in the rear or in the front of the trike.

Figure 15: Non-Recumbent Design Figure 16: Aesthetically Pleasing Concept Figure 17 and Figure 18 are similar designs that are recumbent bicycles. Figure 17 is a two wheeled bicycle that could include a saddle bag for storage and has many options for placing a motor. Figure 18 is a similar design, however the storage is on the rear and a headlight could easily be placed on the front of the bicycle.

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Figure 17: Side and Rear Views of a Potential Design

Figure 18: Visibility and Storage

Figure 19, Figure 20 and Figure 21 demonstrate various three wheel recumbent designs. Figure 19 shows a design for weather protection. Figure 20 demonstrates the use of lean steering with the pedals of the trike in front of the front wheel but behind the fairing. Figure 21 illustrates a trike with cowing that covers the exterior of the trike.

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Figure 19: Weather Protection

Figure 20: Under the Seat Steering Concept

Figure 21: Aesthetically Pleasing Recumbent Concept

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6.0 Concept Selection 6.1 Data Analysis and Calculations for Feasibility and Effectiveness

Analysis Power Analysis To begin power analysis, four forces must be taken into account. The force equation is as follows: SDRT FFFFmaF −−−==Σ Eq. 1 where FT is the tractive force, FR is the force due to rolling resistance, FS is the force due to increasing slope and FD is the drag force. FT is termed the tractive force and is the variable for which Equation 1 will be solved; this is reflected in Equation 2: maFFFF SDRT +++= Eq. 2 The last term ma is known as the inertial force. It is the force that is sensed when the vehicle accelerates, and it is due to mass’s property of inertia. To complete the power analysis, each of these terms must be evaluated in order to determine the tractive force that the motor will have to provide for the vehicle. Rolling Force Rolling resistance is defined in the following equation: rR mgCF = Eq. 3 where mg is the total weight including the vehicle, operator, and cargo (380 lbs) and Cr is the coefficient of rolling resistance (0.01). The total force due to rolling resistance is 3.80 lbs. This force is considerably less than the other terms in the force equation. Drag Force Drag force is defined in the following equation:

ACvF DD2

21 ρ= Eq. 4

where ρ is the density of air (2.38 x 10-3 slug/ft3), v is the vehicle velocity, CD is the drag coefficient (0.12 estimated for streamlined vehicle and 1.1 for an upright vehicle), and A is the frontal area (5.00 ft2 estimated for streamlined vehicle and 5.50 ft2 for an upright vehicle). 16 Force Due to Positive Grade The force due to increasing slope is defined in the following equation:

25

)(grademgFS = Eq. 5 where m is the total mass, g is acceleration due to gravity and grade is described as a percentage. Three grades (5%, 10% and 15%) were analyzed. Results By solving for the tractive force, the required power to drive the system can then be evaluated using the following formula: vFP T= Eq. 6 where FT is the tractive force and v is the velocity. The required power was evaluated for both streamlined and upright vehicles with constant speeds between 0 and 30 mph with a constant grade of 0%. The relationship can be seen in Figure 22.

0.0

0.5

1.0

1.5

2.0

2.5

0 5 10 15 20 25 30Velocity (mph)

Pow

er R

equi

red

(Hor

sepo

wer

)

Recumbent

Upright

Federal Limit

Figure 22: Power Requirement for Constant Velocity, Zero Slope

There is an advantage of using the streamlined design over the upright design. The majority of the time the vehicle is operating it will be traveling at a constant velocity. The amount of power that can be saved by using the streamlined design is the main basis for choosing a recumbent design over an upright design. This large increase in efficiency was a major factor in the group’s decision to choose a recumbent design over a typical, upright bicycle design. Although all calculations were performed for both the recumbent and upright designs, in order to meet all customer requirements and still stay below the federal limit on motor size for a vehicle of this classification, a streamlined, recumbent

26

bike would be the best design. Therefore, the remaining calculations throughout this section only concentrate on the recumbent design. Figure 23 demonstrates that about 2 HP at the drive wheels is required for this vehicle to ascend a 5% grade at the maximum speed of 30 mph that was established by federal codes. Also significant is the fact that with 2HP this vehicle can ascend a 15% grade at a constant velocity of about 12 mph. This is an important figure because almost all city roads are designed to have a grade less than 15%. This means that the vehicle will be able to travel on any major road at a reasonable speed completely unassisted by human power.

0

1

2

3

4

5

6

0 5 10 15 20 25 30Velocity (mph)

Pow

er R

equi

red

(Hor

sepo

wer

)

5% Grade

10% Grade

15% Grade

Federal Limit

Figure 23: Power Requirement for Constant Slope, Constant Velocity

Figure 24 demonstrates the required power to accelerate to various speeds over a period of ten seconds. It was decided through benchmarking and safety analysis that the vehicle should be capable of accelerating to a speed of 20 mph in 10 seconds. Figure 24 demonstrates this benchmark should be attainable with a 2HP motor.

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0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 2 4 6 8 10Time (s)

Req

uire

d Po

wer

(Hor

sepo

wer

) vf = 10 mphvf = 15 mphvf = 20 mphvf = 25 mphFederal Limit

Figure 24: Power Requirement through Constant Acceleration

It bears noting that acceleration was found to be the most demanding mode of operation in terms of power requirement. With the desired acceleration on level ground, the 2HP federal limit is exhausted. Any additional power for acceleration including an incline will need to be delivered by the rider. Braking Calculations Safety is always a principal concern throughout development of any product. A vehicle’s ability to decelerate in a timely manner, while remaining in control is a key safety concern. One of the target specifications was to implement a braking system that will allow the vehicle to stop from a speed of 25 miles per hour in a distance of 30 feet. To determine whether this is feasible, the required braking force and torque must be found. To find these figures, the required rate of deceleration and the required time to decelerate must be found. Equations 7 and 8 are basic constant acceleration dynamics equations that can be used to find these numbers. xavv of Δ+= 222 Eq. 7 atvv of += Eq. 8 where vo is the initial velocity (25 mph = 36.67 ft/s), vf is the final velocity (0 mph), a is the acceleration for which Equation 7 is solved, Δx is the distance through which the deceleration must occur (30 ft), and finally t is the time it will take for the vehicle to come to a complete stop. For these conditions the acceleration is -22.41 ft/s2 and required time is 1.64 seconds. The drag force and force due to rolling resistance will

28

assist the braking force. However, the drag force will continually change throughout the deceleration while the force due to rolling resistance will remain the same. Equation 9 can be used to find the braking force: brd FFFma −−−= Eq. 9 where m is the total mass (11.80 slugs) , a is the acceleration (-22.41 ft/s^2), Fd is drag force, Fr is the force due to rolling resistance, and Fb is the braking force. Using the braking force and a wheel radius of 10 inches, braking torque can be found using Equation 10. rFbb =τ Eq. 10 where τb is the braking torque, and r is the wheel radius. The Hayes Disc Brakes company lists their El Camino mountain bike hydraulic braking system’s torque range as 0 – 230 ft-lbs.17 It can be seen from Table 6 that throughout deceleration, the required braking torque remains between 216 and 217 ft-lbs. The benchmark information proves the target specifications for braking to be feasible. If the required torque is distributed between two brakes, the braking torque is very feasible.

Table 6: Drag Force, Required Braking Force, and Required Braking Torque through a deceleration from 25 mph in 30 ft t (s) x (ft) v (ft/s) Fd (lbs) Fb (lbs) τ (ft-lbs)

0 0.00 36.67 0.960 259.65 216.37 0.1 3.55 34.43 0.846 259.76 216.47 0.2 6.89 32.19 0.740 259.87 216.56 0.3 9.99 29.94 0.640 259.97 216.64 0.4 12.87 27.70 0.548 260.06 216.72 0.5 15.53 25.46 0.463 260.14 216.79 0.6 17.97 23.22 0.385 260.22 216.85 0.7 20.18 20.98 0.314 260.29 216.91 0.8 22.16 18.74 0.251 260.36 216.96 0.9 23.93 16.50 0.194 260.41 217.01 1 25.46 14.26 0.145 260.46 217.05

1.1 26.78 12.02 0.103 260.50 217.09 1.2 27.87 9.78 0.068 260.54 217.12 1.3 28.73 7.54 0.041 260.57 217.14 1.4 29.37 5.30 0.020 260.59 217.16 1.5 29.79 3.06 0.007 260.60 217.17 1.6 29.99 0.81 0.000 260.61 217.17 1.7 29.95 0.00 0.000 260.61 217.17

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Another concern is keeping the vehicle in control. One main control concern is ensuring that the wheels will not lock during deceleration. To ensure wheel lock does not occur the total braking force must remain less than the total friction force between the wheels and the road. Equation 11 can be used to find the friction force: μNf FF = Eq. 11 where Ff is the friction force, FN is the normal force, which is the weight of the vehicle on level ground (380 lbs), and μ is the coefficient of friction, which is between 0.7 and 0.8 on dry ground. Using a coefficient of friction of 0.7, the friction force was found to be 266 lbs, which remains above the range of Fb. However, adverse road conditions create cause for concern with the small difference between Fb and Ff . 6.2 Concept Screening The conceptual design process started out with sketches being developed based on the needs statement and customer input. The sketches were presented to the group with their key points highlighted by each member. After this first presentation, a list of criteria or key points was developed. This was done in order for the group to recognize the positive aspects of each concept. With this list in mind each member went back and refined their design in order to increase its efficacy at meeting customer needs and the group’s feasibility requirements. Efficacy with respect to the conceptual design process means that the concept successfully meets all the major criteria set out by the customer and also the requirements of the class, such as lending itself to energy efficiency. Feasibility of a concept is heavily dependent on the team’s situation. To be more specific, a feasible concept must be able to be manufactured within the time, money, and facilities constraints that are inherent in this project. With the newly developed list of criteria, the group produced nine unique conceptual designs. This time almost all criteria were displayed in each design which showed how concept refinement brought the group closer to meeting the customer needs. The nine were then narrowed down to six that were representative of all the designs. The next step in the process was to narrow the designs down to the three which best exemplified the goals of the group. In order to do this, the list of criteria was weighted and the concepts scored against each other in order to rank the designs. Once they were ranked, the top three were picked for further research and refinement. It was verified that these designs displayed the best aspects of the original nine concepts. Throughout the process all designs were kept on file in order to draw ideas from as needed. The three designs chosen from the first round of selection are shown in Figures 26, 27, and 28 in section 6.3. Customer research is an ongoing process. With that said, the team has decided to incorporate the ongoing refinement of the conceptual designs into the survey process in order to obtain customer feedback. Research and power calculations have moved the group to favor a recumbent design, which brought up the question of customer acceptance. During preliminary testing of the recumbent design for feasibility and stability, the public seemed interested and receptive even stopping to take pictures of the

30

unique vehicle. This showed the team that a recumbent design holds promise as a marketable alternative vehicle. 6.3 Concept Development, Scoring and Selection As stated in the previous section, Team 6 began developing the concept upon analyzing customer requirements. Figure 2 in Section 2.1 shows the weighted criteria that were used by each member of the team to begin the conceptual design process. When it was agreed what aspects of the design were most crucial, each member of the team was to come up with a design sketch taking these aspects into consideration. These designs were used at first to help make some major decisions about likely qualities that the final design should have. This first wave of designs was simply discussed as a group rather than actually ranking the different designs. After these designs were reviewed, several aspects were chosen for a second wave of concept generation. From these nine, six designs were representative of the others Table 6 below shows the Pugh chart that was used to determine which of the remaining six designs were worth further development.

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Table 6: Initial design comparison to narrow the scope of which concepts to continue development.

Concept Values Selection Criteria A B C D E F Weather Protection - 0 - 0 + 0 Comfort 0 + 0 + + + Compactability + 0 + - - 0 Size + + + 0 0 0 Aerodynamics/Efficiency 0 0 - + + + Safety/Visibility 0 + + 0 + 0 Feasibility/Cost 0 + 0 - - 0 Storage + + + + + + Cornering + + + 0 0 0 Stability 0 0 0 + + + Aesthetics 0 - + + + 0 Niche Market/Business Opportunity + + 0 + + + Pluses 5 7 6 6 8 5 Sames 6 4 4 4 2 7 Minuses 1 1 2 2 2 0 Net 4 6 4 4 6 5 Rank 4 2 4 4 1 3 Continue No yes no no yes yes

In Table 6, six designs were presented; each with different styles of frame, drive train systems, two and three wheel designs, and differing outer body construction. Each design was then given a “plus” if its design sufficiently accounted for the criterion listed in the first column, a “zero” if it was neutral on that particular criterion and a “minus if the design lacked any consideration of the criterion in question. Each design then totaled the pluses, subtracted from that total the minuses, and the resulting score was used to rank them. This process narrowed the conceptual designs down to a list of three possible designs whose features were capable of undergoing further development to reach the final design.

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Figure 26: Concept B Two Wheel Recumbent

Figure 27: Concept E Three Wheel Enclosed Recumbent

33

Figure 28: Concept F Three Wheel Recumbent

The next step taken in the scoring and selection of a design was to re-evaluate the selected three designs under a refined set of criteria. The initial design selection took into account many of the customer requirements and criteria based on previous data collection. The second revision of the design concepts was done with designs which more closely fit the scope of the project and the capability of the team, resources, and time requirements. Tables 7 and 8 below show the revised criteria used to develop the design requirements. Table 7 evaluates the three final designs according to the target specifications; in contrast Table 8 evaluates the final designs according to customer specifications. Each criterion was then weighted based on its importance from customer feedback as well as team intuition as to what aspects were most crucial to further development of the final design. The three selected designs were introduced above in Figures 26, 27, 28. Each team member ranked the designs (denoted as B, E and F) on a scale from 1 to 5, with 5 being the best in each of the categories listed on the left. The combined weighted score of all team members is represented in the Total Score row, and each design is ranked beneath that. This chart shows that the design which best fit the customer requirements and project scope was a two wheeled, recumbent style hybrid vehicle. Although the design with the highest ranking was Concept B, all three concepts were closely rated and positive aspects will be incorporated from all conceptual designs if necessary as more research is completed. It has been decided to incorporate a third wheel for greater stability and storage space. The intention is to further develop the framework to accommodate optimal storage and motor capacities.

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Table 7: Concept Scoring Chart Based on Weighted Target Specifications

Concepts B E F

Selection Criteria Weight Rating Weighted

Score Rating Weighted Score Rating Weighted

Score Ease of Manufacturing 20% 4.89 0.98 2.44 0.49 3.89 0.78

Safety 25% 4.11 1.03 4 1 3.44 0.86 Portability 5% 3.78 0.19 2.56 0.13 3.56 0.18 Compactability 5% 2 0.1 2.11 0.11 3.44 0.17 Storage 15% 3.33 0.5 4.11 0.62 3.78 0.57 Aerodynamic 10% 3.89 0.39 4 0.4 4.33 0.43 Aesthetics 20% 2.78 0.56 4.22 0.84 3.11 0.62

Total Score 3.739 3.583 3.611 Rank 1 3 2

Table 8: Concept Scoring Chart Based on Weighted Customer Requirements

Concepts B E F

Selection Criteria Weight Rating Weighted

Score Rating Weighted Score Rating Weighted

Score Portable 34% 3.89 1.31 2.67 0.9 3.56 1.2 Efficiency 17% 4.22 0.71 3 0.5 4.44 0.75 Performance 6% 4.44 0.28 4 0.25 4.22 0.27 Marketability 43% 4.22 1.83 3.89 1.68 4 1.73 Total Score 4.128 3.339 3.943 Rank 1 3 2

7.0 Final Design Refinement Introduction The engineering design process is intricate and iterative. In order to make sound decisions about the design of a new product, several different design methods should be taken into consideration. Design for Manufacturability and Assembly (DFMA), Value Engineering (VE), and Design for Safety (DFS) should all be taken into consideration throughout the design process. For this project all system level and primary subsystem level decisions were made by the entire team utilizing the engineering design methods. The following sections give a general overview of information about DFMA, VE, and DFS and how these methods can be applied to the Senior Design project. These design methods are then discussed as they specifically apply to several system level and

35

subsystem decisions; such as the decision to build rather than buy a bicycle frame, the material selection, the method to integrate two separate power systems, the decision to utilize lean steering, and the final hub motor choice. All of these decisions had significant impacts on other parts of the system, and therefore were made by the entire team with much regard for the basic engineering design methods. Figure 29 shows the final system design at the end of winter quarter.

Figure 29: Final Assembly of Vehicle

Design for Manufacture and Assembly (DFMA) The method of Designing for Manufacturability and Assembly is generally taking into account how individual parts will be fabricated and how components will be put together throughout the design process. The goal of these efforts is to lean the process from the beginning, meaning a savings in time, material, labor, and ultimately cost. With proper design considerations less skilled workers or even automated processes can complete tasks with less chance for error. The resources posted on the ME471 website give a good introduction to assembly and covering items such as reduction in total number of parts, self location, eliminating adjustment, interchangeability of both parts and tooling as well as information whose purpose is to get the designer in an assembly mindset. Also included on the ME471 website is a good introduction to individual part considerations such as reducing the number of manufacturing processes and tooling changes as well as other key issues. The sum of this information will give the individual members a good basis for optimizing component designs as well as helping to fit those designs with the overall system level DFMA initiative. Additionally, the focal points for DFMA will investigate additional resources such as material cost evaluation processes, which could be beneficial to this project. An example of DFMA is using two self locating bushings rather than three individual parts which require careful installation. This simplification saves time, reduces the number of parts, and allows unskilled workers or automation to complete an assembly task. Some steps that can be taken to increase the manufacturability of a part include:

36

• Minimize the machining processes for a given part • Minimize the number of tooling changes required • Use standard sizes for holes and bolts • Use the same size materials throughout the design (ie. same diameter tubing) • Reduce number of precision parts and measurements

Some steps that can be taken to improve the assembly of a system include:

• Reduce the total number of parts • Encourage modular assembly • Use self-locating parts • Use reusable fixturing • Eliminate adjustments • Require little to no experience for assembly personnel

Principles of DFMA have been considered throughout the design process of this vehicle. Although the first design of the vehicle did not have sufficient DFMA consideration, after the system was split into several different parts that each of the members were to analyze, DFMA became more central to the design process. Design iterations were driven mostly by DFMA for the lean steering assembly as well as the suspension knuckle. More specifically, the design of the bushing assembly has been simplified on the lean steering. The first iteration used 18 total pieces for the bushings while the second iteration uses only 12. A second advantage of the latest design is that the bushings are self locating which will speed assembly time. Thirdly the update to the design has saved 33% in material cost for the bearing assembly. As for the suspension knuckle, an investigation into a single cast piece has begun. This change would not only reduce machining cost but also allow automated welding of the much simplified design. As one can already see, DFMA will be a great help to the bottom line of this project. Further DFMA considerations for the various parts of the assembly can be seen in Appendix D. Figure 30 below shows specifically the individual parts of the overall system that DFMA considerations were applied to throughout the design process. Each letter points to a different part and the area of the report that information regarding the DFMA of that part can be found is also shown below. A: Lean Steering, Appendix D, pages 88-91 B: Connecting Pins, Appendix D, pages 92-93 C: Rear Frame, Appendix D, page 94 D: Front Knuckle, Appendix D, pages 95-100 E: Rear Knuckle, Appendix D, pages 101-103 F: Y-Frame, Appendix D, pages 104-107 G: Storage, Appendix D, pages 108-120

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Figure 30: Individual DFMA Sections

Value Engineering Value engineering is a tool used to optimize a process and analyze available options when making a decision. It focuses on the function of a process in an attempt to cost effectively optimize performance. The two most important factors in value engineering are function and cost. To add value to a process, the general function of that process needs to be met with as little unnecessary cost as feasible. Another way to incorporate value engineering is in the design of mechanical parts and systems. Value is added when the manufacturing and production costs of a product are minimized. Therefore, value is added when a product is designed and optimized with the manufacturing process in mind. One example of value engineering that was incorporated into the design of the vehicle was the change in the Y-frame’s connection bar. This decision was based primarily on the effects it has on the manufacturing processes involved. By using a piece of tubing that is already being used for the rest of the Y-frame, less manufacturing processes were necessary. This is a value engineering decision because the basic function of the part was considered, and a decision was made to perform that function as inexpensively as possible. Value engineering was useful when deciding to implement lean steering into the design. Lean steering added marketability to the overall vehicle by making the vehicle more appealing to the customer. Even though fewer parts are incorporated in using a rigid body the increased stability increases the safety of the overall vehicle. This increase in safety

G

A, B

F

D, E C

38

adds more value to the customer than the few added parts that can be cost effectively incorporated. The decision to add storage also took into consideration value engineering. This addition was also important to the customer and added value to the overall design. Another way value was added to the design was through the incorporation of a lock. These additions increased the cost of the vehicle but it will also increase the value. Design for Safety The method of Designing for Safety generally is a process by which an engineer anticipates failure modes relating to the overall safety of a product, and strategically implements a plan to prevent such failures from occurring. The overall safety of a product includes the safety of its users, of any at-risk nonusers, and of the environment. A crucial element of this method is to address safety issues through failure modes analysis before they can arise in the final product. Designing for safety has benefits outside the realm of product usage as well. As the Institute for Safety in Design points out, integrating safety decisions in the early stages of design not only reduces risks but also:

• Improves productivity • Decreases operation costs • Avoids expensive design corrections, such as in the case of recalling faulty

products18 These benefits are a result of a safe, quality product. When a product sufficiently incorporates safety into its design, the savings and benefits are reaped all the way back to manufacturing and production. These benefits are a result of fewer repairs, and potential liability costs. In devising a strategy to thoroughly incorporate safety in the design of the vehicle, the team used the book Design Through Safety by the National Safety Council as an additional reference. This text has a chapter on important concepts to address when incorporating safety into the design process. Such concepts include user friendliness, hazard recognition and mitigation, cost factors, and general risk identification.19 Safety considerations for the user are the foremost concern of this method. Particularly in the design of a vehicle, the operator’s safety must be addressed with every design decision that is made. Some failures of a vehicle that affect the safety of the operator include:

• Structural Failures: Stresses, Strains, Fatigues • Performance Failures: Stability, Power, Traction, Braking

For these types of user safety concerns, special care was taken in assigning appropriate factors of safety for each component of the vehicle. The safety of at-risk nonusers is incorporated into the design of products whose usage can affect people other than the operator. In this case, these safety factors arise in the consideration of visibility components such as lights, reflectors, and turn signals. Where these components can’t be designed with numeric factors of safety, special attention must be made in the design decisions to make the vehicle safe for others to interact with in travel. Safety of the

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environment is also a high priority concern in today’s engineering design decisions. The vehicle addresses this issue head on by offering an alternative to conventional internal combustion powered vehicles. Furthermore, this issue will be considered in design by selecting optimal motors and battery components so as to minimize the use of electricity for recharging. Dynamic load factors were used in conjunction with factors of safety to incorporate safety in the analysis of the structural components of the vehicle. When applying the loads to the seat under-bar, a dynamic load factor of 2 was used. This was done by using a load of 500 pounds for the rider and 60 pounds for the storage. This loading takes into account the types of conditions the vehicle will encounter when it is ridden over bumps and other road conditions causing dynamic loads within the vehicle. Figure 31 below demonstrates where this dynamic load was applied when analyzing the Y-frame of the vehicle.

Figure 31: Incorporating dynamic load factor of 2, the loads applied to the Y-frame

were double the actual weight of the rider

Another method of designing for safety that the team performed was the failure modes and effects analysis (FMEA). This process is performed by systematically identifying the most crucial failure modes of the entire design. Table 9 shows the list of system and sub-system level components as well as all possible failures that occur for each part. This list was then rated by the whole team as to each failure mode’s severity. The most severe failure modes were further investigated using the “Five Why’s” cause analysis. An entire

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analysis performed by this method is included in Appendix E. This FMEA technique allowed the group to identify a very large range of physical and operational potential failures. The “Five Why’s” analysis helped to identify the root cause of each failure mode. It also served to show that many failure modes can be traced back to the same root causes. By identifying the most severe of failure modes, and their root causes, the necessary precautions were incorporated into the design of the vehicle to ensure the maximum amount of safety for the user.

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Table 9: System and sub-system level components, and potential failure modes System Level

Category Sub-system

Part Failure Mode

Fracture/Yielding Weight Distribution

Bending Insufficient Suspension

Corrosion Overall Weight

Frame

Uncomfortable Fairing Fracture/Yielding

Over Lean Hard to Lean

Accidental Over Steering Poor Turn-ability

Lean Steering

Joints Fracture/Yielding

Bending Corrosion Fork

Bearings Fracture

Uncomfortable Loosening

Unbalanced Seat

Corrosion Falls off

Misaligned Spoke Burst

Structural Systems

Wheel

Flat tire Chain Fracture

Corrosion Bent Sprocket

Excessive torque or power required Jumps between Gears

Gear Shifter is Inoperable

Human Power Drive

Bearings Inoperable Motor Drive Corrosion Corrosion Inoperable Batteries Overheat

Poor Performance Brake Pad Shear Cause Pitch over

Kinematics Systems

Brakes

Corrosion Inoperable Dislocation

Burn Out due to Wires Lights

Not enough Battery Power Inoperable Dislocation

Burn Out due to Wires

Electrical Equipment

Displays

Display is Incorrect

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Build Rather Than Buy Frame One important decision for Team 6 was the judgment that it would be more beneficial to design and build the vehicle’s frame rather than buy and modify an existing frame for the final design. This decision was made after consideration of the function required by the frame and many different design methods, including design for safety, value engineering, and design for manufacturability. With regards to designing and analyzing the vehicle for safety, building the frame rather than buying it was the choice for several reasons. In using an existing frame, there is a chance that the shape and general design was created for a particular set of loading conditions. Most existing frames also are built of non-standard shaped tubing. The exact shapes of the tubing would be difficult to create in SolidEdge. This would therefore make it difficult to accurately analyze the frame with finite element analysis. Figure 32 below gives an example of one such frame geometry that would be particularly difficult with which to work. By choosing to design rather than buy the frame, it can be tested thoroughly with hand calculations and finite element analysis and modified as necessary to assure that failure will not occur in operation.

Figure 32: Example of existing Y-frame that would be difficult to model, analyze,

and modify due to its unique geometry20 Value engineering was an important design method considered in making the decision to build rather than buy the frame. There is much value added to the overall project by designing and building a specific frame for the project that meets all specifications rather than trying to buy and modify a frame. Although the cost of buying existing frames in bulk may be less than the cost of manufacturing the designed frames, there will still be additional costs to modify existing frames. It would cost more to have added manufacturing operations such as making cuts and other modifications to an existing frame, than it would be to make a frame. Therefore, the overall cost of designing and building the frame will ultimately be less if the manufacturing of certain modifications

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necessary in a purchased frame are considered. Also, because the manufacturability of the frame has been taken into account during design, the manufacturing processes that will be necessary in building a frame are known and can be optimized. Whereas if a frame were to be purchased and modified, the necessary manufacturing processes could be more complex and time consuming. For example, cutting and re-welding large members of a purchased frame is a demanding manufacturing process. Frame and Structural Member Material Selection Selection of an appropriate material type is an important part of the design process. The focus of this section is on the major structural subsystems of the assembly that will be subjected to the majority of the vehicle’s forces and stresses. These include the Y-frame, the rear frame, the lean steering assembly, and the knuckle connection. Most of the other components that are incorporated into the final design are catalog items. Some of these items may have a variety of material options, and if a material decision was made concerning these options it will be discussed in the section of the report pertaining directly to that particular component of the vehicle. There are many factors that went into selecting a material, such as requirements that originate from the customer, the target specifications, the manufacturability considerations, the stress analysis, and cost. Some customer requirements that effect the material selection include aesthetically pleasing, light weight, and safe. The types of material properties that will fulfill these requirements are: strength to weight ratio and yield stress for safety, density for weight, as well as weld-ability and corrosion resistance. The target specifications that are of particular importance when selecting a material include capability of carrying a 250 pound person and 30 pounds of extra cargo. This specification affects material selection in accordance with the stress analysis. Manufacturability is another important consideration that affected the selection of material. Manufacturing processes such as heat treatments, welding, and general ease of metal machining are all affected by the type of material that is used. Aluminum 6061-T6 was chosen to be the material used for the previously mentioned structural subsystems of the vehicle. As for the aesthetics, aluminum is easily anodized and painted. These processes serve to protect the material from rust, which keeps the vehicle looking new as well as functional and aesthetically appealing for a longer duration of time. They also allow for easy application of paint and designs, specifically for aesthetics. When this material was assigned to the solid model of the vehicle, SolidEdge output a total weight of less than 16 pounds as can be seen below in Figure 33.

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Figure 33: Solid Edge output of weight for the structural subcomponents

where Aluminum 6061-T6 is the material selected

One target specification was that the entire vehicle must weigh less than 100 pounds. Aluminum effectively serves to allow the vehicle to meet this specification. Sixteen pounds for the major structural components is very reasonable, as it only accounts for approximately 22% of the non-storage weight of the vehicle. Another target specification that is met by using Aluminum is cost. Carbon fiber and aircraft grade steel alloys offer great strength at very low weight; however these materials are far more costly than the Aluminum that was selected. As Table 10 below shows, the general price per foot offered from McMaster-Carr for T6 Aluminum is about $14.00. The total cost of material at this rate would be around $200.00 for the specified sub-components. This also is a reasonable number, only making up approximately 13% of the allowable target specification for manufacturing costs of $1500.00.

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Table 10: Cost and material property comparisons for potential bike frame materials

MATERIAL Al 6005-T1

Al 6061-O

Al 6061-T6

EMS-Grivory

GC-4H 40% Carbon Fiber

AISI 1010 Steel, Cold

drawn Ti

Aircraft-Grade 4130 Alloy Steel

DENSITY 0.0975 lb/in³

0.0975 lb/in³

0.0975 lb/in³

0.0477 lb/in³

0.284 lb/in³

0.163 lb/in³ -

ULTIMATE TENSILE

STRENGTH 24700 psi 17000

psi 45000

psi - 52900 psi 31900 psi -

YIELD TENSILE

STRENGTH 15200 psi 7000 psi 40000

psi

29400 psi (AT

BREAK) 44200 psi 20300

psi 75000

psi

ELONGA-TION AT

FRACTURE 16 % 25 % 12 % 8 % 20 % 54 % -

COST (per foot) $14.04 $14.04 $14.04 $34.43 $22.06 $148.13 $98.56

*Cost estimates are from McMastercarr.com, using the longest stock size One other very important consideration that went into selecting Aluminum 6061-T6 was its yield stress. Table 10 shows that the maximum allowable stress before yielding is 40ksi. The factor of safety that was selected for the structural components was 3. This, combined with a dynamic load factor of 2 for analysis, ensures that the vehicle will be safe to operate under a variety of conditions. Aluminum 6061-T6 Aluminum sufficiently provided the strength necessary to keep the maximum stresses within the bounds of these safety factors. One example of this can be seen in Figure 34 below where the Y-frame structure of the vehicle was analyzed in Algor. The maximum occurring stresses in the part were near 9000 psi resulting in a factor of safety of 4.4 with respect to plastic deformation due to max load. One further benefit of this material is that it does not displace a great deal before its fracture point as can be seen in Table 10 above. The image also shows where and how the Y-frame would displace under the loading conditions that the vehicle will undergo. This is of particular importance for the application in the vehicle. A material that plastically deforms, even without failure, would make for complications in the congruence of the entire vehicle system as well as for the comfort of the operator. The differentiating aspect of T6 Aluminum, as opposed to other Aluminums, is its pre-tempered qualities. The structural subsystems that would be using this material will all be involved in a welding operation at some point in the assembly, which means the material will need to be re-tempered to return its strength and durability qualities. Though this leads to added manufacturing cost, the material needs to be hardened before manufacturing processes are performed. Aluminum without the tempered qualities is too soft to manufacture efficiently.

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Figure 34: Algor snapshot of results analysis of Aluminum T6 Y-frame

Selecting the proper material for the appropriate subsystems of the vehicle that will be undergoing the bulk of the system stresses was a crucial decision to be made. 6061-T6 Aluminum has proven to sufficiently stand up to the requirements set forth by the customer, the target specifications, the cost, the manufacturability, as well as the occurrences of safe stresses and deformations.

Power System Integration Integrating human power and electric power is an important decision to Team 6’s final design. Human power will increase the trike’s reliability; the vehicle will be operable even when the motor is inoperable. This integration affects the overall design of the vehicle in various aspects. The wheel that is driven by human power will affect the type of gears used and the placement of the pedals. Conversely, the wheel or wheels that are driven by the motor will affect the type of motor that can be purchased and the design of the rear of the trike frame. Taking the system into consideration the integration of human and electric power could be evaluated. There are two general methods for integrating more than one power source to drive a vehicle: parallel and series hybrids. Figure 35 shows an example of how each method could be applied to drive the vehicle. Both methods for integration are currently being used in industry and have associated pros and cons. Series hybrids have lower overall

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efficiencies than parallel hybrids; however, series hybrids do not require a complex transmission that has the ability to handle multiple input power sources and to propel the vehicle. Transversely, parallel hybrids are more efficient, but require a transmission that is able to integrate multiple power sources. In this situation, there is also a higher weight associated with series hybrids because of the generator that charges the batteries with human power.

Figure 35: Power Integration Options

After conducting research and consulting with Dr. Urieli it was decided that human power and electric power could be integrated through the road most effectively. Team 6’s initial customer pricing requirement also helped make this decision. The customer did not want to spend more than $1500 for this vehicle; the independent integration is the most cost effective way to integrate the two power systems. This integration allows one wheel to be driven by human power and one or two wheels to be driven by a motor. It was soon realized that the wheel driven by human power could most effectively be placed in the front of the trike producing a front wheel human power driven vehicle. Placing the human power on the front wheel of the trike will increase the functionality of the trike; however, this will take time for the rider to get used to. The time it takes the rider to gain experience and familiarity of the front wheel drive is not a significant enough factor to eliminate front wheel drive. The value gained by placing the human power in the front of the trike and making the vehicle front wheel drive out ways the concerns with lack of customer familiarity with front wheel powered trikes. Our team’s experience riding an available front wheel powered bike showed that it takes very little time to adapt to the front powered arrangement. This design then allowed one of the rear wheels to be driven by a hub motor. Utilizing a hub motor in the rear and front wheel drive eliminates the

Human Power Electric Power

Electric Motor

Generator

Propulsion

Series Hybrid

Human Power

Electric Power Transmission

Electric Motor Propulsion

Parallel Hybrid

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need for a chain that spans the length of the trike. Not only does this simplify the design, it also increases the overall safety of the trike. All human power gearing will be contained in the front of the trike and the motor components will be centralized at the rear of the trike; this can be observed in Figure 36.

Figure 36: Illustration of Human and Electric Power

The function of the independent power system varies depending on the operator and the path they are traveling. A customer riding the trike for exercise may opt to not use the motor while operating the trike and only use the human power aspect. However, a customer riding the vehicle as an energy efficient means of traveling a short distance at higher speeds may use the motor while riding. The integration of human and electric power will allow the customer to increase the amount of torque applied to the wheels, providing more power than the motor or the rider could independently apply. This increase in torque allows the vehicle to increase its maximum travel speed and the speed when traveling up a hill. After benchmarking similar products it was evident that most bicycles incorporating both forms of power do it independently. Figure 37 shows a bicycle that is manufactured by weRelectrified which incorporates human and electric power independently. The motor used on this bicycle can be sold separately and is marketed as a hub motor that works without the immediate interaction with pedals11. According to customer reviews on the website11 the kit is easy to install and operate; it allows someone to ride their bicycle without pedaling or without pedaling excessively to travel at faster speeds. Figure 38 is another motorized bicycle that is marketed as having human and electric power independently; this vehicle also uses a hub motor21. Figure 39 shows a tricycle that is powered only by human power. This tricycle has pedals that are only linked to one rear wheel. This benchmarked item illustrates the possibility of powering one rear wheel with a power source and maintaining normal operation21.

Hub Motor Electric Power

Gearing Human Power

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Figure 37: weRelectrified Bicycle with human and electric power11

Figure 38: Miami Sun Retro 7 go-hub e-cruiser which incorporates human and

electric power21

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Figure 39: Lightfoot Cycles Roadrunner with human power on one back wheel21

Potential failure modes of these human and electric power systems include the need of excessive torque on the pedals to operate the human power, and an inoperable motor. The independent integration of human power and electric power increases the reliability of the vehicle. This integration allows the vehicle to be operable even if the motor is inoperable since each system does not depend on each other. Conversely, if a component of the human power drive train fails, the hub motor can be used to get the operator to his or her destination.

Lean Steering Mechanism The decision was made by Team 6 to use a lean steering mechanism in the rear of the three-wheeled vehicle. This mechanism allows the three-wheeled vehicle to behave similar to a bicycle while cornering in order to provide more stability. This was an extremely important decision to the overall design of the vehicle and has impacted many aspects of the vehicle throughout the design process. Such a large decision required the team to look at the lean steering mechanism from many different perspectives, including function, safety, economics and value, customer requirements, and design for manufacturability. Since no member of Team 6 had a particularly large knowledge base of what lean steering is or how it works prior to this project, a great deal of research on lean steering had to be completed before a sound decision could be made about whether or not to incorporate it in the final design. First, research was done online to ensure that this idea would be feasible and within the scope of the project. It was found that lean steering mechanisms are already used on custom trikes by independent builders because they help to increase stability and decrease the axial forces on the spokes during turns. The feasibility of this idea was confirmed through a mock-up as well. Plans for a simple lean steering mechanism were found online and used to create a mock-up, which is shown in Figure 40. A mock-up of the lean steering mechanism was fabricated using wood and pizza pans, and this helped illustrate that the mechanism could be easily built and that it indeed works properly.

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Figure 40: Lean Steering Mock-up

One of the main considerations in the decision to incorporate lean steering into the design was the overall safety of the vehicle. Three-wheeled vehicles are inherently unstable in tight turns, but the lean steering mechanism helps eliminate this turning stability issue. The lean steering mechanism allows the rear wheels to lean around turns, meaning that this three-wheeled vehicle will behave similar to a bicycle around turns, which will considerably increase its stability. Safety and comfort were two important aspects that the customers mentioned in surveys, and lean steering helps to improve both safety and comfort while cornering. Customers also reported that they would like an overall innovative design for the vehicle, and Team 6 feels that lean steering helps provide this innovation. As with any major decision the financial impact of the lean steering mechanism also had to be considered in order to make sure that the value gained from implementing this system is worth the added money that will need to be spent. After building the mock-up and looking at the components that will be needed for the lean steering device, it was decided that this will not significantly increase the cost of this vehicle. In fact, it will only be slightly more costly than having a solid rear section to the vehicle. The estimated manufacturing cost of the entire lean steering mechanism is $133. This cost estimate is calculated in Appendix F. Although $133 is a relatively large manufacturing cost, it should be noted that this also represents a large portion of the overall vehicle design. Appendix F shows that nearly all the manufacturing cost comes from material costs and operations that would exist regardless of whether lean steering was implemented or not. In fact, one of the only extra costs to the lean steering is the pins that are necessary, which represents a very small added cost. Also, from a value engineering standpoint, adding this lean steering mechanism will indeed add considerable value to the vehicle by contributing to the vehicle’s niche market appeal as an innovative design and improving the safety and comfort of the vehicle while cornering.

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After making the decision to implement lean steering, Team 6 also worked to find ways to design the system for manufacturability. Some of the items that were considered when creating a final design of the lean steering mechanism were: holding to a simple design with few parts, using standard size bearings and connectors, using similar components as the rest of the vehicle, using self-locating bushings, creating simple jigs, using the same material as the frame, and having a modular assembly. All of these considerations, while simple, will add up to a more easily manufactured lean steering mechanism. Team 6 made the decision to implement lean steering on the rear portion of the device after showing that the mechanism will provide considerable value to the vehicle with little added cost in material or manufacturing expenses. Research has also confirmed that this mechanism will indeed be feasible and a mock-up was fabricated to show the functionality. This decision also had to be made in a timely fashion because it directly affects the system as a whole. For example, the motor selection and failure analysis of the vehicle could not be completed until this decision had been finalized. The decision to use lean steering on the vehicle directly impacted the type of motor that was selected for the vehicle. A vehicle with lean steering is much more complicated to attach a standard motor to than a vehicle with a rigid rear end. The power transmitting components, such as gears and belts that are needed for a standard motor to operate properly would be difficult to incorporate in a vehicle with a dynamic rear wheel base. This became one of the primary reasons that the team decided to implement a hub motor in the final design over a standard motor that requires gears and belts to transmit its power to the wheels. As was stated earlier, the decision to use lean steering in the final design of the vehicle had an affect on many other aspects of the vehicle design. Lean steering was the paramount reason for using a hub motor, which had further affects on the vehicle design. Although the decision to use a hub motor meant that a motor mount and power transmission system did not have to be designed, a method to attach the hub motor from both sides was needed. Figure 41 shows the final design of the lean steering mechanism that allows the hub motor to be mounted from both sides.

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Figure 41: Lean Steering Design

In addition to ensuring that the hub motor could be mounted from both sides, other DFMA considerations also had to be looked at while finalizing the lean steering design. For example, Figure 42 shows a close-up of the final design of the lean steering. The vertical drop-outs were included to make the assembly and attachment of the wheels easier. The figure also shows the 180 degree bends of the rear wheel attachments. Considerable design modifications and research went into the final decision on the attachment of the rear wheels. The utilization of a hub motor required that a design be created which allows the wheels to be attached from both sides because of the design and weight of the hub motor. Most of the benchmarking that was found regarding rear wheel attachment was bulky and inefficient. Therefore the team developed an innovative new way to attach the rear wheels by bending aluminum tubing of the top of the rear wheels in order to give connection points on both sides.

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Figure 42: Lean Steering DFMA Example

Research had to be completed to ensure that these bends in the aluminum tubing would indeed be feasible. These 180 degree bends can indeed be completed with the diameter tubing, wall thickness, and bend radius that will be used for the lean steering mechanism. This bent tubing would cost $30.25 a piece if purchased, however, for the final manufactured vehicle, this process would be less expensive if manufactured in house.22

Figure 43: Lean Steering Bent Tubing

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Hub Motor Choosing between a standard DC electric motor and a hub motor for this vehicle is an important decision. Standard motors come in larger variety of sizes, wattages, and available torque. However, hub motors free up more space to be used for other features. This decision, although important, is still dependent on other key factors such as frame design. A previously made decision to use a standard 26 inch diameter mountain bike tire for availability, height (visibility of the rider), and better stability with respect to smaller tires brings in to question the availability of a hub motor compatible with that diameter tire. Also the decision to implement lean steering for greater maneuverability affects the complexity of the drive train. The greater the vehicle leans the less likely a standard chain or belt drive would be applicable. Vendor information shows that it is possible for a hub motor to meet our speed specification (30mph). However these high powered hub motors are not widely available and thus more expensive than the budget will allow. Using the power equations in Section 6.1, Table 11 shows what can be achieved with a more commonly available and lower cost 600W hub motor with respect to target specifications.

Table 11: Comparison of target specifications with 600W hub motor Category Target Available (600W)

Top Speed 30mph 24.9mph Acceleration 20mph/10sec 13.6mph/10sec 5% Grade 10mph 13.0mph

Complete 600 W hub motor kits that come with batteries for 20+ mile range and 8 hour charging time are available. Also included in these kits are: controllers, throttles, battery chargers, and key switches. However, the target specifications in top speed and acceleration will not be met with electric power alone. The original purpose of having a wheel driven by human power was for reliability, but now the human power aspect will provide more as an additional power source capable of delivering on average approximately 0.2-0.25 hp (150W – 187W) for a two hour period.23 With a hub motor and the absence of a chain there is a higher overall efficiency than that of the standard DC motor and chain/belt drive counterpart. Rims can be bought for hub motors that fit a standard 26 inch diameter tire. One disadvantage is that consumers may not be familiar with the hub motor and how it works. Along with this unfamiliarity, having a three-wheel vehicle which is driven by one back wheel may cause the vehicle to turn because of unbalanced torques. To test this potential problem, Team 6 pushed one back wheel of a tricycle with independent rear wheels, as seen in Figure 44. The conclusion from this mock-up is that a three-wheel vehicle wills not deviate from its path.

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Figure 44: Mock-up of single rear wheel drive

A hub motor is lighter than the average standard DC motor and saves weight in the finished product. Also having a motor incorporated into the hub of the wheel with the lean steering system eliminates the need for a specially designed mount that would have to lean with the frame. This decreases the risk of chain/belt drive tangling causing damage to the vehicle and/or the rider. With the above mentioned simplification, the frame will be less complicated to manufacture since another moving part will have been eliminated. However, a hub motor is design to be mounted from both sides. With the decision to have the motor drive a rear wheel and not the front wheel, the lean steering design was modified. The additional cost for this fork, using the given cost analysis in Appendix F, is $69.74 per vehicle using Aluminum 6061-T6 tubing. Each of the back wheels will be supported on both sides, allowing for a hub motor to be mounted on either or both sides of the vehicle as seen in Figure 45.

Figure 45: Hub motor mount on lean steering

In searching for a hub motor it was important for Team 6 to find a hub motor kit that provided the components needed that would be compatible with the hub motor. The hub motor that has been selected for this vehicle is the BD36 produced by Wilderness Energy. The BD36 was chosen because of its cost (with kit), ability to meet calculated specifications, and the manufacturer can supply the quantity needed. The motor is a 36V 600W brushed hub motor. A comparison of several hub motor options is shown in Table

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12. The cost of a hub motor ($159.00) is more than that of an equivalent standard motor ($100.00 average). The warranty offered by the vendor is a 90-day all inclusive motor repair guarantee.24 The average cost at a bicycle shop of a replacement rim is $20.00. The average cost at a bicycle shop of a set of replacement spokes is $8.00.24 Total labor cost to re-spoke or replace the rim is approximately $30.00. Hub motor brushes are rated by Electric Vehicles USA (a distributor) for 7,000 to 8,000 hours of use. This means that if you use a motor for 4 hours per day everyday under normal riding conditions, the brushes will last approximately 4 years before needing to be replaced. If the motor is completely damaged, Wilderness Energy has a number of licensed distributors throughout the United States (268), Mexico (1), and Canada (16).24 It is important to note in this application lead-acid batteries must be charged immediately after use. The conversion kit available from Battery Space comes with nickel-metal hydride batteries, which weigh less than lead-acid batteries and do not lose charge if not immediately charged. However, Team 6 decided the ten pound weight reduction was not worth the extra cost ($320.95).

Table 12: Comparison of available hub motors kits

Team 6 has decided to use a BD36 hub motor for the three-wheel recumbent vehicle, as shown in Figure 46. The BD36 will meet the speed specifications for available hub motors with appropriate battery power. A hub motor will allow for a design that reduces the risk of cords and chains being tangled while turning. As a result, maintaining the safety of the rider and performance of the vehicle while keeping the frame simple and easier to manufacture.

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Figure 46: Final Hub Motor Selection9

Build Rather Than Buy Storage After some feedback and further evaluation of the storage design, Team 6 decided to re-evaluate current design as whether to buy storage and modify it to fit the dimension or continue with the design to manufacture the storage. Some of the main concerns of manufacturing the storage are the complexity of the manufacturing process and the production and material cost that are attached to it. Purchased storage would need, or could be modified, to have to following desired features:

• 12” X 8” X 18” cargo space • Waterproof • Fit within dimensions of lean steering • Lightweight • Attach to seat post of Y-Frame

Figure 47: Example of Waterproof Storage

Although existing products were found that met some of the features, each was missing a key component. Most waterproof containers were large enough to accommodate the necessary cargo space. However, mounting between lean steering would be awkward as

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they opened length-wise (Figure 47). The retail cost of these containers averaged $110.00, which does not include the cost of adequate modification. Whereas the cost of building storage with the desired function would cost $65.00, using the provided cost estimation formula. By building the storage all off the desired features can be included at a lower cost than buying and modifying available storage. Although the storage will be built, there have been design modifications to address concerns raised by peers. For example, the laptop compartment and the mesh screen have been removed to reduce the complexity of the manufacturing process. These changes can be found in Appendix D: Storage. Weather Protection In the beginning of this project, one of the target specifications of the final design was to have a weather protection system to protect the rider from the elements. After conducting research on existing products for weather protection of bicycles, it was decided to drop the weather protection feature for the final design. This decision was based on the additional cost for the amount of protection it has to offer. The average cost of existing products is $320 for a lexan bubble with a mounting system. A method of manufacturing the bubble was researched as well and found that an equivalent bubble could be produced at a cost of $234; still a high added cost the final design. Figure 48 shows how the bubble would be included in the final design and the amount of protection the rider would have from the elements.

Figure 48: Final design with bubble weather protection

Thermal Calculations of Battery Container

The BD-36 Hub Motor kit comes with three 12V sealed lead acid batteries in a cloth carrying case. Whereas the scope of this project is to have a vehicle capable of travel in light precipitation, the accompanying case in insufficient. The carrying case included vents allowed water to enter which would damage the batteries. Team 6 decided to use a battery container made from the same material as the frame (Al 6061-T6). The battery container (Figure 49) can be welded directly to the frame between the wheels of the lean steering mechanism.

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Figure 49: Standard Battery Container

With the removal of the vents, it was decided to do calculations to determine the surface temperature of the proposed battery container. Also, heat transfer analysis was performed to determine at what velocity the vehicle could travel without damaging the batteries. Through research it was learned that the optimal operating temperature for a sealed lead acid battery is 25°C (77°F).25 Also, for every temperature increase of 8°C the battery life will be cut in half.25 For example, traveling for 2 minutes at 33°C will be 4 minutes of battery life. Although the battery would still function, for range purposes, Team 6 wanted to keep any temperature increase under 33°C (91.4°F). In addition, alert the operator of the vehicle to the temperature increase. To estimate the heat from the battery the following equation was used:

(12)

The mass of the batteries, 27 lbs (12.25kg), is mostly lead material, which has a specific heat of 129 J/kg.K. A temperature range between 25°C and 33°C is evaluated as the heat to be removed. Using this Q, the surface temperature of the material can be calculated for a given time.

(13)

Where k is the conduction coefficient of Al 6061-T6, 167 W/m.K. The surface area (A), 0.2464 m2, can be found from the outer dimensions of the container, 12.8” Long X 6.8” Wide X 5.3” Height. The material thickness (L) is 0.4”. Assuming that the internal surface temperature is the same as the battery temperature (Tb), the external surface temperature (Ts) is calculated.

(14)

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Figure 50 shows the relationship between the battery temperature and the external surface temperature as a function of the heat from the battery (Q). Due to the thin layer of material and the relatively high conductivity of the aluminum, there is only a fraction of a degree change in the temperature. With a small change in temperature a thermal gauge can be placed on the outside of the container that can give direct temperature measurements.

0 2000 4000 6000 8000 10000 12000 1400025

26

27

28

29

30

31

32

33

Heat generated by Batteries, Joules

Bat

tery

and

Con

tain

er T

empe

ratu

res,

Cel

sius

BatteriesContainer

Figure 50: Battery and Container temperature as a function of heat generated by

the battery

Using the surface temperature and a given air temperature while riding, the velocity of travel to remove heat from the container can be calculated over a given time period. Note: On the day of testing it was 27.0°C (80.6°F) and the average air temperature while riding was 21.8°C (71.2°F). The time periods evaluated were between 3 and 7 minutes. Assuming that heat can only be removed from the four 12.8” long sides parallel to travel (Ap = 0.2 m2), the velocity can be calculated from the following series of equations. The convection coefficient of the flowing air:

(15)

Solving for Nusselt Number, Nu, given the length of the box and the conduction coefficient of air (kair = 0.257 W/m.k):

(16)

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Note: For all cases studied, the Nusselt number resulted in laminar flow. Using the above relationship to solve for Reynolds Number, Re, the combined wind and vehicle velocity necessary to remove the heat completely can be found over a given period.

25 26 27 28 29 30 31 32 330

5

10

15

20

25

30

35

40

45

50

Battery Temperature, Celsius

Vel

ocity

to re

mov

e ex

cess

hea

t, m

ph

30 Minutes

9 Minutes

7 Minutes

6 Minutes

5 Minutes

4 Minutes

3 Minutes

Figure 51: Combined velocity necessary to reduce battery temperature to optimal in a

given period of time

In Figure 51, the relationship between temperature and velocity can be seen over the given time intervals. For example, if the vehicle were to remain outside with a steady wind of approximately 1 mph, the battery container would be cool from 33°C (91.4°C) to 25°C (77°C) in 30 minutes. During testing, using only the motor, the maximum temperature reached by the batteries was 30.8°C. Decreasing motor speed and supplementing with human power will decrease the battery temperature at a more rapid rate. Cost Estimation Cost estimation was conducted according to the “Recommended method for determining production costs (for lots of 5000)” distributed to the OU ME Senior Design Project. The estimation includes labor, overhead and equipment, materials and components and is calculated according to the following equation: Total Cost = (total time to complete operation)(labor rate for the operation)[1 + (basic

overhead factor) + (equipment factor) + (special operation/tolerance factor)]

A time estimation was calculated for each manufacturing process including setup, clean-up and quality assurance. Three levels of labor rates were used according to the level of

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skill required in each step. A basic overhead factor of 100% was suggested to cover worker benefits, maintenance and utilities. An equipment factor of 50% was suggested to cover amortized costs, consumables and service to keep equipment in working order. Finally, a special operation / tolerance factor of 25% was added to processes that require special machines or have extremely tight tolerances. Table 13 shows the vertical support of the lean steering cost estimation sheet as an example. The remaining estimation worksheets can be found in Appendix F.

Table 13: Cost Estimation for Lean Steering Vertical Support Operation Operation 1 Operation 2 Operation 3 Operation 4

Cut tube to correct length

Hole Cutting (top and

bottom hole)

Clearance material

removal (top and bottom)

Quality check for

measurements

total time to complete operation(s) in hours 0.03 0.1 0.1 0.1labor rate for operation $12.00 $12.00 $12.00 $12.00labor cost = (3 x 4) $0.36 $1.20 $1.20 $1.20basic overhead factor 1 1 1 1equipment factor 0.5 0.5 0.5 0.5special operation / tolerance factor 0 0 0 0labor / overhead / equipment cost = 5 x (6 + 7 + 8) $0.90 $3.00 $3.00 $3.00purchased materials / component costs $2.62 Sum of total costs $12.52

As can be seen in Table 14, the total cost for production was estimated to be $1,347.47 for the entire vehicle.

Table 14: Overall Estimated Vehicle Manufacturing Cost Component Cost

Cruz Bike 300.00 Hub Motor 258.40 Y Frame 123.57

Lean Steering 90.62 Front Knuckle 16.31 Rear Knuckle 39.48 Rear Frame 20.10

Storage 67.58 Miscellaneous Components 80.00

Total 1000.00 Conclusion After considering design methods of various aspects of the vehicle several decisions were made. It was decided that it would be more beneficial to build the trike’s frame rather than buy an existing frame for the vehicle. This decision affected the entire system and

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directly affected the material choice. Aluminum 6061-T6 was chosen after considering various materials because it has appropriate yield strength, weight and cost characteristics. Another important system decision made involved the powering system of the vehicle. Team 6 decided it would add more value to design a parallel hybrid tricycle rather than a series hybrid to avoid a complex transmission system and achieve a higher efficiency. Lean steering was chosen to increase stability in turns and helps to corner a niche market. This decision then led Team 6 to decide on using a hub motor as electric power. This choice also increased the safety of the vehicle by eliminating complex drive system that a conventional electric motor would need. Including all of these decisions, the estimated manufacturing cost for the vehicle is at the target cost. 7.1 Initial Problem Statement Drawings were attached as a separate file, Team 6 CAD Drawings.pdf.

Table 15: Bill of Materials Y Frame

No. Part Qty Description Weight Cost

1 Main Chassis 4.75 ft 1.5” nom x 0.125” wall, Aluminum 6061-T6 6.27 lb $18.09

2 Seat Post 1.33 ft 1” nom x 0.250” wall, Aluminum 6061-T6 0.92 lb $5.63

3 Pin 1 0.5” dia., 3-13/32” long, Zinc-Plated Steel Pin 0.17 lb $5.00

4 Bushing 1 2” x ½” x ¾” SAE 841 Bronze Bushing 0.02 $5.00

5 Front Knuckle 1 Cast Item, Aluminum 6061-T6 0.563lb $0.56

Lean Steering No. Part Qty Description Weight Cost

1 U-Forks 88 in. 1” box tubing with 1/8” wall thickness 1.94 lb $17.37

2 Vertical and Horizontal Members

85 in. 2” flat bar with 1/8” wall thickness 2.07 lb $18.25

3 Pin 4 0.375” dia., 2-1/4” long, Zinc-Plated

Steel Pin 0.28 lb $17.20

4 Pin 2 0.375” dia., 2-

27/32” long, Zinc-Plated Steel Pin

0.15 lb $9.14

5 Bushing 8

SAE 841 Bronze Flanged Sleeve

Bearing ¾” x 5/8” x 3/8”

0.08 lb $10.00

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6 Bushing 4

SAE 841 Bronze Flanged Sleeve

Bearing 1” x 5/8” x 3/8”

0.04 lb $6.40

Rear Frame

No. Part Qty. Description Weight Cost

1 RF Tubing 1 1.5" OD round tube, ⅛ wall thickness,

6061 T6 Aluminum 0.184 lb $12.22

2 RF Knuckle 1 Cast block, 6061 T6 Aluminum 1.20 lb $1.18

Storage

1 Lid 0.375 lb ABS – Medium Strength pellets 0.375 lb $0.67

2 Connection Bar

.75” x 2” x 9”

ABS – Medium Strength stock bar 0.452 lb $5.51

3 Main Storage 3.110 lb

ABS – Medium Strength pellets

3.110 lb $5.55

4 Foam 798 in² 1/8” Polyethylene foam 0.056 lb $6.53

5 Latch 1 set 2” Steel hasp latch 0.030 lb $1.00

6 Hinges 2 set 2” Polyethylene flat hinges 0.050 lb $4.36

7 Lock 1 set Brass padlock 0.100 lb $5.50

8 Strap 1 Velcro strap 0.020 lb $5.70

9 Bolt & Nuts 9 sets #10 x 5/8” Zinc Plated Steel 0.001 lb $1.20

10 Washers 9 Zinc Plated Steel Flat Washer 0.001 lb $0.50

Miscellaneous Components Outside of Project Scope

No. Part Qty. Description Weight Cost

- Remainder of Components -

Wheels, Suspension, Gears, Brakes,

Cruzbike 70 lb $119

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7.2 How does it Work Hub Motor Operation of the trike is similar to the operation of a bicycle with the incorporation of a hub motor. The hub motor does not need to be used to operate the vehicle. It can operate independently with the pedals located at the front of the trike, as shown in Figure 52.

Figure 52: Front Wheel driven by human power

The hub motor can be turned on from the controller with the key, when the key is turned to the green dot the motor is on and when turned toward the red dot the motor is off. The key does not need to be in the controller to remain on. The power light on the throttle, shown in Figure 53, will be on when the motor is on.

Figure 53: Power light on the throttle

The throttle is located on the handle bars and will control the speed of the vehicle. When the motor is on and the throttle is pushed down the motor will begin moving the trike.

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The battery life will be increased if the motor is not the sole means of starting the vehicle. The battery power indicator is also located on the throttle, as shown in Figure 54.

Figure 54: Battery Power indicator on the throttle

The controller connects to the battery box, the hub motor and the throttle. The green and blue wires from the controller connect to the hub motor and the red and black wires connect to the battery box. This connection is critical to the safety and the operation of the vehicle. The battery box also has a wire which connects to the charger, shown in Figure 55. The charger is separate from the battery box but will come with the batteries. After using the motor the batteries should be charged until the light is green indicating that the batteries are fully charged. The batteries will have a longer life if they are charged regularly and not run until they are completely empty.

Figure 55: Battery Charger Connection

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Pedals The pedals can be adjusted from the front Cruz Bike bar, as shown in Figure 56. There is a quick release adjustor that allows for easy modification.

Figure 56: Pedal Adjustment

Storage Just like any other storage, the lid can be opened by lifting the lid, while padlock key is supplied to unlock the padlock. The Velcro strap inside the main compartment can be used to strap laptop or laptop bag securely. No more than 30 lbs of load should not be placed in the storage. Lean Steering The incorporation of lean steering allows the trike to act as a bicycle. In a rigid three wheel design a rear wheel can loss contact with the road while traveling, this is eliminated with lean steering. The leaning mechanism, shown in Figure 57, allows the trike to lean up to 42°. The lean steering does not directly turn the vehicle; this mechanism allows the user to travel at higher speeds around turns and while maneuvering the vehicle.

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Figure 57: Maximum lean obtained by the rider is 42°

Two rear wheels are assembled into the lean steering forks; each wheel has a rim brake connected to it, as shown in Figure 58. These two rear brakes are controlled by one brake lever which is located on the right side of the handle bars, as shown in Figure 59. There is a third rim brake located on the front wheel which is controlled by the brake lever on the left side of the handle bars.

Figure 58: Brake on rear wheel

42°

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Figure 59: Handle bar brake lever

Rear Frame The purpose of the rear frame assembly is to serve as a connecting structural member between the Y-frame and the lean steering assembly. The rear frame and Y-frame are connected above the knuckle by the frame’s primary suspension shock. These two features are what provide a suspension beneath the rider, allowing the vehicle to safely handle bumps and vibrations without causing significant discomfort to the rider. Figure 60 below shows an image of how the rear frame is integrated into the overall vehicle frame assembly.

Figure 60: Rear Frame integrated with Knuckle and Lean Steering

Start-Up Procedure A rider with experience riding a front wheel driven vehicle this vehicle will be easy for them start. If the rider would like to use the hub motor assist it can be turned on with the key being turned to green dot on the controller as discussed above.

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A rider without experience riding this type of a vehicle may need more assistance to start the vehicle. The hub motor can be used to start the vehicle. The rider should begin the vehicle moving slowly and then start the hub motor to increase the speed. The vehicle is easier to control while traveling at higher speeds. Once the vehicle is moving the rider can begin pedaling or use the hub motor as desired. Maintenance To maintain safe operation of the vehicle the tire pressure should be checked regularly. The brakes should also be checked by the rider or the local bike shop for wear and positioning, this should be done to verify a safe stopping distance. The wires should also be checked before operation to make sure they are secure to the vehicle and not dragging on the ground or in the way of the tire’s rotation. If a light is not working the battery should be replaced in the light. 7.3 How is it Made Y- Frame

Figure 61: Y-Frame

The Y-frame is manufactured mostly out of 1.5 inch outer diameter Aluminum 6061-T6 tubing with 0.125 inch wall thickness with the exception of the seat post which is manufactured using 1 inch outer diameter Aluminum 6061-T6 tubing with 0.250 inch wall thickness. The first process in the production of the Y-frame is to rough cut a

Seat Post

Horizontal Member

Vertical Support

Angled Member

Steer Tube

Front Knuckle

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portion of the 1.500 inch outer diameter tubing to 5.700 inches using the horizontal band saw. This piece will be used for the steer tube. The steer tube should then be faced off on a lathe to the final dimension of 5.590 inches. While on the lathe the steer tube also needs to be bored out in order to seat the bearings for the steer column. The steer tube should be bored 0.500 inches deep on both sides to an inner diameter of 1.330 inches for the bearings. The angle member is also made from 1.500 inch outer diameter stock, rough cut to 31.750 inches using a horizontal band saw. Also, rough cut a 45 degree angle on one end of the angled member. Smooth 45 degree end and deburr so that it properly fits into the front knuckle. Using a vertical mill, notch the other end of the angled member to a 0.750 inch radius at an angle of 65 degrees. The same stock will be used to rough cut 12.750 inches with the horizontal band saw. This length will be used as the horizontal member. One end of the horizontal member is notched to a 0.750 inch radius at a 45 degree angle. The vertical support is rough cut to 7.400 inches and then notched out to a radius of .75 inches on both ends. Cut a notch perpendicular to one end. The notch on the opposite end of the work piece is made at a 45 degree angle. The next step in manufacturing the Y-frame is the fabrication of the seat post. The seat post is made by rough cutting the 1.000 inch outer diameter tubing to a length of 16.000 inches on the horizontal band saw. Then one end of the seat post is notched at a 75 degree to the stock with a radius of 0.750 inches. Again, this notching operation can be performed on the vertical mill. The tolerances for all of the members of the Y-frame are ± 0.010 inches which can be obtained on the horizontal band saw. These tolerances are tight enough that the Y-frame components will be assured to assemble correctly, and the Y-frame itself will assemble with the rest of the vehicle. However, the tolerances are not overly tight so as to require another machining operation beyond the horizontal band saw when cutting the parts to length. The final individual component of the Y-frame that must be fabricated is the front knuckle. This component will be sand cast out of Aluminum 6061. In order to be sure that the front knuckle fits properly with the rear knuckle, after taking it from the mold the excess surfaces must be ground off and the inside needs to be smooth. After all of the individual components of the Y-frame have been created, this subassembly must be welded together. A jig will be used to weld all of the components together to ensure that all of the angles are measured precisely and that none of the parts move during the welding process. A picture of an example jig can be seen in Figure 62, however, this jig was just created out of wood for the purpose of creating the prototype. The jig for the manufacture of the Y-frame in bulk quantities would be a more permanent jig made of steel. The tolerances for the angles in the Y-frame construction are ± 1 degree. These tolerances can be easily obtained by creating accurate jigs, and they are tight enough to ensure the components can be assembled properly. After setting up all of the components of the Y-frame in the jig, they can be easily welded together using a MIG welder. After welding the Aluminum parts together, they lose their T6 temper and must

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be heat treated again afterwards. Finally the Y-frame must be inspected for dimensional accuracy and quality, and then painted.

Figure 62: Example Jig

Rear Frame The tolerances used in the drawings for this subassembly were decided upon based on the need for precision. Some dimensions, such as tubing length, are not as critical to the quality or manufacturability of the vehicle due to the way they are assembled. In this case, it is sufficient to cut the round tubing to length with a band saw operation. The tubing is then welded into place in the subassembly. Due to the nature of these processes, the tubing lengths need not be any more precise than ± 0.010 inches. Other dimensions, such as those that define the rear knuckle do have tighter tolerances, on the order of ±0.005 inches. These tolerances come from the need for alignment among the parts being assembled. For example, the rear knuckle is a connecting point for two rear frame tubes, as well as the front knuckle and the pin connection that is made there. In order to ensure proper fits of all these different assembly parts, more precise machining and tolerances are necessary. The rear frame assembly consists of three parts cut from 1.5 inch outer diameter tubing stock, a cast rear knuckle, and a piece of 2 inch flat stock. Figure 63 below shows what the orientation of these components.

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Figure 63: Rear Frame integrated with Lean Steering Connection

Figure 64: Components diagram for rear frame.

Lean steering connection, the rear frame lean steering connection, is cut to 8.625 inches long using a horizontal band saw. A 0.375 inch hole is drilled into each end of the part at a distance of an inch from the end to the center holes. The rear frame’s bottom bar is cut to a length of 15.75 inches. The top is rough cut to 15.250 inches long, and then a 77 degree angle is cut on one end of the work piece. The rear frame up-right, part 4, is cut to 7.500 inches long, a 0.750 radius notch in then cut at a 78 degree angle. The rear frame assembly has four production manufacturing operations. The first operation is to cut the three pieces of bar tubing to proper length as described above. The tolerance on these cuts and this operation are ± 0.100 inches. The second operation in this assembly is to weld all five parts together. This operation includes loading the parts into a fixture and welding. A skilled operator is needed to perform this task. The

Lean Steering Connection

Top Bar

Horizontal Bar

Vertical Bar

Rear Knuckle

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third operation is inspection and cleaning. This operation will inspect the quality of the welds, and check the dimensionality of the assembly. Furthermore, the welds and the surface of the metal will be smoothed down wherever there are large burs, dents, or scratches. This will ensure the paint will adhere, and allow for optimal aesthetic appeal. The last operation is to apply the primer and paint. These last two operations are performed by a standard, unskilled operator. The rear knuckle is a cast part that would be produced by an outside supplier. Assuming a near net shape cast part, there would still be a need for an operation to touch up all holes and rough edges where welds and pins are to be located. Lastly, there would be an inspection of this part before it is sent to the weld operation discussed above. Lean Steering

Figure 65: Lean Steering

The lean steering is manufactured out of 1 inch Aluminum 6061-T6 box tubing with a 1/8 inch wall thickness and 2 inch Aluminum 6061-T6 flat stock with 1/8 inch wall thickness. All components of lean steering can be manufactured independently and then assembled. Five parts need to be manufactured to assemble the interior of the lean steering. The four horizontal bars are identical to one another. The horizontal bars can be made by cutting 2 inch Aluminum 6061-T6 flat stock with 1/8 inch wall thickness to a length of 16.500 inches using a band saw. On each end cut a 45 degree angle on the corners of the part with a band saw. Three holes should then be drilled with a 0.750 inch bit through the part at 0.688 inches, 8.250 inches and 15.812 inches from an end. The vertical bar can be made by cutting a 2 inch Aluminum 6061-T6 flat stock with 1/8 inch wall thickness to a length of 8.875 inches with a band saw. Two holes should then be drilled with a 0.750 inch bit at 0.688 inches and 7.938 inches from an end.

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Figure 66: Lean Steering Interior Components

Six total parts need to be manufactured to assemble the two forks that connect the rear wheels. The fork’s cross bar should be cut to 6.000 inches out of 1 inch Aluminum 6061-T6 box tubing with a 1/8 inch wall thickness on a band saw. Then 45 degree angles should be cut on each end of the tubing. The fork’s inside bar should be cut to 20.375 inches in length from 1 inch Aluminum 6061-T6 box tubing with a 1/8 inch wall thickness on a band saw. One end of the part should then be cut at a 45 degree angle using a band saw. The pin locations can then be drilled with a 0.375 inch drill bit at 0.750 inches and 8.000 inches from the straight end. These holes should be drilled on the outside surface as shown in Figure 66. The wheel connection can then be milled on the surface perpendicular to the drilled holes with a 0.188 inch mill on the outside of the bar to a length of 3.375 inches. The fork’s outside bar should be cut to 16.875 inches in length from 1 inch Aluminum 6061-T6 box tubing with a 1/8 inch wall thickness on a band saw. A notch should then be milled out with a 0.188 inch mill from the end of the part into the part 0.688 inches on the inside of the piece. Another notch should then be milled out with a 0.375 inch mill from the end of the part to 0.875 inches on the outside of the piece.

Horizontal Bars

Vertical Bars

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Figure 67: Lean Steering Fork

To assemble the fork a jig should be constructed similar to the jig shown in Figure 68. The three members can be placed in the jig so that the 45 degree angled members can be welded together, using this jig will help ensure a ±1 degree tolerance. Once the fork’s parts are welded together the brake mounts can be welded onto the fork. At the completion of welding the entire fork can be heat treated to return it to T6 hardness.

Figure 68: Jig for Fork

Once both forks have been welded and heat treated, attachment of the brakes, wheels, and the hub motor can be attached. Each half of the V-brake assembly is slid onto one of the

Inside Bar

Cross Bar

Outside Bar

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two studs which have been welded to the fork. Care is taken to insert the brake prong into the correct hole on the stud. Once the V-brake is seated on the stud, a hex socket cap screw is threaded into the stud to hold the brake in place. When the full bike is assembled a brake cable will be inserted into the top of the V-brake arms. The process should be repeated on the other fork. To attach either the wheel assembly or the hub motor assembly, the fork is held in a jig and said assembly is slid into the notches which were milled in the fork. A washer and nut is then put on each side of the axle and tightened down securely. If the assembly is of the hub motor type, care is taken so the wire does not become damaged before the full lean steering assembly is put together. To assemble the lean steering sub assembly a jig is of paramount importance. First 6 pins are inserted into the jig and held upward by their heads. Next the single vertical support is placed onto the center pins. Next the two horizontal bars are placed on all 6 pins. Next the fork containing the hub motor is placed over the pins on the right side of the jig followed by the fork containing the wheel on the left side of the jig. Then the other two horizontal bars are placed over all 6 pins. Finally the vertical bar which was welded to the rear frame and heat treated is placed over the middle two pins. Finally snap rings are used to fasten the pins securely. Throughout this assembly process the proper bushings and washers are inserted onto the pins where appropriate such as between the horizontal bars. The wire for the hub motor should then be placed in the plastic retainers along the bottom of the horizontal bars and forward to the front of the rear frame. Once the components are assembled the part should be checked to make sure it leans smoothly to 42 degrees. When the part is verified to lean at 42 degrees the part should be painted. Storage Figure 69 shows the manufactured and assembled storage final design. It consists of three main components, which are to be manufactured separately – the main compartment, the lid, and the connection bars. Each of the main components is labeled in Figure 69 for reference.

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Figure 65: Storage Final Design

All of the main parts can be manufactured to a tolerance of ± 0.050 except for the lid and the connection bars which require tighter tolerances of ± 0.010 inches. This is because the lid must provide a good seal for the main compartment in order to provide weather protection for the storage. The connection bars also must have tight tolerance so the holes can be fitted through back post tightly when the storage is mounted. By using rapid injection technique to fabricate the storage, these tolerance specifications are achievable 26 . As opposed to high precision injection molding, a rapid injection molding machine can produce parts at higher speeds but at the expense of its accuracy. However, because the tolerances for this storage container are not very tight, it is more beneficial to use the rapid injection process because of its high production rate and low manufacturing cost. 8.0 Conclusion This project was aimed at satisfying the following needs statement:

Energy-appropriate 1 passenger compact vehicle for moderate weather conditions: There is a need for a compact single passenger vehicle powered by alternative energy that will be marketable for intra-campus and intra-community travel. The vehicle must address the problems of pollution, oil dependency, oil consumption, parking, and fuel costs. The vehicle also needs to address storage capabilities. It must be high quality, safe, aesthetically appealing, and reliable.

Connection Bars

Lid

Main Compartment

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The needs statement was defined quantitatively with target specifications. These specifications were based off customer surveys, federal regulations, and also satisfying the needs statement. The goal of achieving all the target specs was not attained, but most specs were surpassed as shown in Table 16. Some of the aspects that were not met were due to the motor selection; however, more powerful motors and batteries are available that can achieve the targets specs that were not reached, such as top speed and fully charged battery life. The cost of manufacturing was overestimated as well as the recharging time; these aspects were realized in the production of the prototype. The other aspects that were reached were designed with the help of SolidEdge and ALGOR, such as maximum load, storage load, and the ability to fit through a standard American doorway. Overall, the success of the vehicle relies on the customer satisfaction and feedback on the prototype.

Table 16: Target Specs and Actual Values # Need Actual 1 The Vehicle Is capable of traveling at speeds of 30 miles per hour 27 mph 2 The Vehicle Will cost no more than $1500 manufacturing $993.55 3 The Vehicle Is capable of carrying 250lb person 4 The Vehicle Will weigh no more than 100lb ~100 lb 5 The Vehicle Is capable of traveling 20 miles between fueling/charging 15-17 miles 6 The Vehicle Will have a security device Controller

Key 7 The Vehicle Is capable of carrying 30lb additional payload in a 12x18x6”

space

8 The Vehicle Will fit through a standard American doorway of 30” 9 The Vehicle Will include functional side view mirrors 10 The Vehicle Will include a headlight, tail-light, and reflectors 11 The Vehicle Will have 10” of clearance between lowest point and ground 12 The Vehicle Fully loaded, will travel up a 5% grade at 10 mph 13 The Vehicle Must be stable in a turn radius of 15 feet at 10 mph 14 The Vehicle Will be aesthetically pleasing 15 The Vehicle Will stop from 25 mph speed within 30 feet 16 The Vehicle Will be easily stored 17 The Vehicle Will have adequate suspension 18 The Vehicle Will have a functional horn 19 The Vehicle Will be environmentally friendly 20 The Vehicle Will accelerate from 0-13 mph in no more than 10 seconds 9 seconds 21 The Vehicle Will be small enough to fit two in one parking space side-by-

side.

22 The Vehicle Will be able to fully charge in no more than 8 hours. 3 hours The overall design incorporated several subsystems including a CruzBike Conversion Kit, a hub motor, and a lean steering mechanism. Every target spec was evaluated and designed for in the prototype. The CruzBike Conversion kit helped with the recumbent aspect of the rider position and pedal usage. The kit originally was intended for the conversion of a mountain bike to a recumbent bike using a recumbent seat and a pedal

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attachment; these components were incorporated into the final design of the project. One important aspect of the CruzBike conversion kit was the adaptability of the pedals and seat to a range of people of different heights. This helped to improve the comfort of many different riders. The hub motor was a key factor in the operation of the trike. Helping with take-off and cruising, the hub motor was very successful within the design, and certainly helped to create the niche market the project was aimed towards. One concern was the torque that the hub motor would apply to the vehicle and how it would affect the handling. The results of testing showed that the hub motor did not affect the rider noticeably. The hub motor also helped with the environmental friendly aspect, relying only on battery power to drive the motor. The lean steering subsystem was the differentiating factor of the design. Allowing the vehicle to lean 42 degrees to both sides, the stability was greatly increased. Higher speed cornering and better handling than a conventional trike were a few characteristics that separated the design from benchmarked existing products. The lean steering system was prototyped and designed for the incorporation of the hub motor, as well as tail lights, battery box placement, and rim brakes. Being a unique system of turning, the lean steering mechanism was the highlight of the overall design, as well as a popular aspect of the vehicle among the customers. The design also incorporated other design aspects for aesthetics, cost, and manufacturability. Some other components include the Y-frame, which gives the vehicle the “bicycle” looks. This simply helps the customer view the trike as a variation of a normal bike, and nothing too different from the function of a bicycle. Also, the Y-frame provides a location to attach the CruzBike components to the vehicle in the same way it is applied to a normal Y-frame bicycle. Shocks designed under the seat and in the headset allow for a comfortable ride for a disturbance at any wheel. Safety equipment such as headlights, taillights, and a horn were implemented into the trike. One of the aspects of the needs statement was the use of an alternative energy. A battery box was designed for the battery to provide a safe location for the battery, and also to provide the right thermal conditions for a prime operating environment. Using the cleanest form of energy available, human power, the vehicle can be assisted by the operator using the pedals. The motor can be assisted at any speed; the more human power assist, the longer the life of the battery. The vehicle can also be operated using only the pedals, for safety concerns of battery failure, etc. The effective use of human power provides the economy with a cost-efficient user-friendly solution that would appeal to those concerned with the energy crisis. A battery box was designed for the battery to provide a safe location for the battery, and also to provide the right thermal conditions for a prime operating environment. Since the vehicle is operated using electric power it decreases the amount of gas being used. Several government agencies are concerned with the energy crisis, and are acting accordingly to provide solutions to this problem around the world. The Department of

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Energy aids many agencies in research and development of alternative fuels and solutions. The Energy Efficiency and Renewable Energy Agency is working to develop hybrid vehicle systems from ranging from light to heavy systems. The agency is researching hybrid vehicle systems, as well as developing methods to design “virtual vehicles” and evaluate vehicle performance. Also, battery simulation, testing, and development are crucial concerns of the Energy Storage Department. Other than the use of batteries, more fuels are being considered and tested for efficiency and applicability to vehicle propulsion systems. The FreedomCAR and Vehicle Technologies Program is a counterpart to the DOE, specializing in “the development of emission- and petroleum-free cars and light trucks and the infrastructure to support them”27. The goal of the program is to eliminate the use of foreign oil and to enhance the energy-efficiency of the United States. The U.S. Environmental Protection Agency, and the Departments of Energy, Agriculture, and Transportation are currently taking actions to comply with the President’s new plan “Twenty in Ten.” The new plan is set to reduce gasoline consumption by 20% in the next 10 years within the U.S. Some aspects of the plan include revamping fuel economy standards for cars and trucks which would reduce fuel consumption within the U.S. by 5% alone. Under this plan, the Clean Air Act is also being enforced on all motor vehicles, and by the year 2017, mandates will require approximately 35 billion gallons of alternative fuels to displace the equivalent amount of gasoline 28 . Actions regarding energy efficiency within the world are already being taken to reduce world-wide pollution and to make the world a better place to live. Energy efficiency is an extremely important subject regarding the future of the world’s energy resources. With the help of science and new technologies, energy can be used in higher efficiency applications and more environmentally-friendly emissions.

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Appendix A: Interview Guide We are seniors at Ohio University looking at designing a Personal Vehicle. This vehicle can be used to travel short distances that you would otherwise drive; such as going to class or work, grocery store for a few items and other short trips. We are looking at a vehicle that would be environmentally friendly and easy to use. We appreciate you taking the time to complete our survey. 1. Choose an age range. 18-22 22-35 35-50 Older than 60 2. What type of an area do you live in? College Campus Large City Small City Outside of a City Other, please specify 3. Do you consider yourself a physically active person? Yes No 4. Do you own a bike? Yes No 5. Do you feel comfortable riding a bicycle on city streets and on streets that have a speed limit less than 25 mph? Yes No 6. If so, how often do you workout a week? 1-2 times 3-4 times More than 4 7. On a given day, what is the longest distance you travel from your residence?________ 8. How far do you travel on an average trip?____________________________________ 9. How important is NOT polluting the environment to you? Very Important Important Not Important 10. Would you be willing to use man-power, such as pedaling, to operate a small vehicle? Yes No 11. How important is storage to you as a function of this vehicle? Very Important Important Not Important

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12. What items would you travel with on this vehicle? Brief Case Groceries Backpack Laptop Other, please specify___________ 13. If an electric bicycle was available for your use would you use it?

Yes No 14. Would you buy this vehicle as a second vehicle? Yes No 15. If you had this type of a vehicle what would you potentially use it for?____________ 16. Should the vehicle have a collapsible aspect to it to further improve on the parking and storage issues of traveling in the United States? Yes No 17. How important are the aesthetics of this vehicle? Very Important Important Not Important 18. Is Performance or Efficiency more important to you? Performance is more Important Efficiency is more Important 19. Are you willing to spend money on a new smaller vehicle for short trips if you have the potential to save money down the road? Yes No 20. How much would you be willing to spend on a vehicle of this type (small vehicle such as a moped with a motor and a man-power feature)?________________________________

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Appendix B: Second Interview Questions We are seniors at Ohio University looking at designing a Personal Vehicle. This vehicle can be used to travel short distances that you would otherwise drive; such as going to class or work, grocery store for a few items and other short trips. We are looking at a vehicle that would be environmentally friendly and easy to use. We appreciate you taking the time to complete our survey.

1. Do you own an electric bike or moped? Yes No

2. Is or Would owning a moped be feasible in your daily life? NOT Feasible VERY Feasible

1 2 3 4 5 3. If you DO own an electric bike or a moped, what feature/features do you like best

about it? __________________________________________________________ 4. If you do NOT own an electric bike or a moped, what features would you like a

moped to have that would encourage you to buy one? (choose as many as you would like)

Lower Cost Convenience Environmentally Friendly Storage Other, please specify _____________________ 5. If you do NOT own an electric bike or a moped, what keeps you from buying a

moped? (choose as many as you would like) Cost Convenience Availability Lack of being able to be used in all Weather Conditions Storage Other, please specify _____________________ 6. Is your visibility on the road while riding a bike or a moped a concern you have? Yes No

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Appendix C: Business Opportunity

STATEMENT OF BUSINESS OPPORTUNITY

Team 6, The Sembilanagon, is working to create a solution addressing the current energy situation of high oil prices and diminishing supplies of petroleum throughout the world. Team 6 has decided to focus on an alternative form of transportation because this particular petroleum based energy problem can be attributed almost exclusively to the transportation industry. It has been acknowledged that there is a need for a lightweight, alternative fuel, personal vehicle meant for use on short distance trips. This vehicle is meant to replace larger, inefficient automobiles for short distance trips that are common in college campus and intra-community situations. Initial designs focus on several elements that were observed through extensive benchmarking and interviews. It was determined that some major points of concentration will be adequate storage, affordability, inclusion of human power, protection from light precipitation, and a streamlined, recumbent design. Streamlined Recumbent Design An important aspect of this design regarding marketability will be the focus on incorporating an aerodynamic, recumbent design. This design will significantly decrease the amount of drag on the vehicle over a regular, upright bike. This will result in a vehicle that is more efficient and requires a smaller motor and fewer batteries. Also, this comfortable, intriguing design that otherwise would not have purchased an alternative form of transportation. Inclusion of Human Power In order to further increase the reliability human power will be incorporated. Human power integration is a viable way to increase the power and efficiency of the vehicle without using a larger motor. Human power is an element that a large majority of people surveyed were interested in integrating into this design. Appropriate Weather Capability Team 6 is interested in marketing this vehicle to as many people as possible. This means that all reasonable climate and precipitation must be considered in the design. Several concepts, including a front fairing on the vehicle and a detachable, weather-protecting cover have been proposed thus far. The goal is to make this vehicle operable in all conditions that one can safely operate an automobile. Adequate Storage Customer interviews have shown that at least thirty pounds of secured storage is necessary to ensure that this vehicle is a viable alternative to an automobile for most short

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trips. This storage capability is something that is commonly overlooked in most current electric scooter and moped designs. Conclusions This vehicle will be marketed towards college students and professors. This large market base is ideal because of the centralized nature of college campuses and the surrounding communities, resulting daily in many short distance trips. The vehicle being proposed will be an excellent alternative to larger automobiles that would normally be used in these cases. This vehicle will save users considerable money on fuel, will help preserve the planet’s energy resources, and will help alleviate pollution and parking problems. This affordable streamlined recumbent vehicle will incorporate ample storage, human power, and adequate weather protection. The frame design and human power will be the main focus of the vehicle; electrical power will also be an important aspect that will be researched and the feasibility of purchasing this component will be evaluated. Emphasis on these major areas will produce a vehicle which is not only energy appropriate but highly marketable.

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Appendix D: Design for Manufacturability and Assembly LEAN STEERING (Alicia Janszen, Chris Keegan, Mark Cimarolli) The lean steering mechanism was designed with a limited number of parts. There are five main frame parts with four of the five being repeated parts. As seen in Figure 1, parts 1 and 5 and parts 2 and 4 are the same parts. The same standard size pin will also be used for each connection point of the assembled lean steering

Figure 1: Lean Steering

There are a limited number of processes that will be done to each part. The wheel connection piece will need to be bent 180° to form a fork configuration that will be wide enough to attach the wheel. There will also need to be a notch attached to the wheel connection so that the wheel can be securely connected. Each part will need to have holes drilled to accommodate the pin connection points. These parts will not need tight tolerances or a finish machining process. The parts will not need to be further machined after they are obtained from the distributor. There will be a few welding processes for the entire assembly. There will be a weld required to attach the tab onto the bottom of the outside post of the fork. There will also be another weld process required to attach the bent tube, which will be fabricated, to the tubing. This welding will require a heat treatment process so that the material will return to its original characteristics. The lean steering will be modularly assembled so that the entire system will not need to be present during the assembly. This assembly will require a simple jig that will connect the lean steering to the rear frame. The original design of the lean steering can be seen in Figure 2. This design did not take into consideration the connection of the two rear wheels. Adding the wheel connection forks as shown in Figure 3 alleviated this problem. This addition did not however increase the number of parts needed for the assembly. The outside parts, labeled 1 in

1

2

3

4

5

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Figure 2, were replaced with the wheel connection shown in Figure 3. This allowed for a wheel connection to be redesigned without adding parts to the assembly.

Figure 2: Original Lean Steering Design

Figure 3: Second Lean Steering Design

There will be a notch and keyhole machined into the wheel connection, as seen in Figure 4, to allow for self location of the wheel connection. This wheel connection will also allow for easy detachment and repair of wheels. Since the hub motor will only be located on one wheel this will eliminate the need for two controllers or the need to find a controller that will accommodate two motors.

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Figure 4: Lean Steering Wheel Connection

The lean steering mechanism was redesigned again after the leaning was analyzed further. The center tubing was rounded to avoid contact with the wheels as the mechanism was leaning, this change can be seen in Figure 5.

Figure 5: Third Lean Steering Design

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There will also be stoppers located on the mechanism to not allow for over lean. The assembly will allow for plenty of location options for reflectors, brakes, lights and a fender, especially on the wheel connection.

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Frame Connecting Pins (Richard Walton) Currently Team 6 is planning to use modular assembly in production of the three-wheel recumbent cycle. The rear frame and the main frame of the vehicle will be connected by the “knuckle” (Figure 1R). The pin that connects the knuckle will need to allow rotation as well as withstand corrosive environmental conditions. An additional place revolute pins will be needed is at the connections for the crossbars of the lean steering, as seen in Figure 1R.

Figure 1R: “Knuckle” Connection Hole Figure 2R: Location of Lean Steering Pins There are three common pin materials to be considered. Steel has high strength characteristics, but connections made from steel can rust. The purpose of this vehicle is outdoor travel and thus susceptible to corrosion. Aluminum and Stainless Steel are both corrosion resistant materials. Fasteners, however, are made usually from steels and stainless steels. A commonly used metal for stainless steel is AISI 304. To decrease assembly time pins with self-location abilities can be used. This can be achieved by chamfering the entry edges of the pins. Also, the parts that the pins will be inserted into can be chamfered and the longer interiors can be tapered to allow the pins to line up with holes on exiting surface. This will allow the pins to be inserted from either side. Through analysis at the pin connections the worst case forces are at the knuckle connection (621 lbs). The worst case force at the lean steering connections is 310 lbs. The depth of each connection of the lean steering is approximately the same dimension. If a spacer is used on the four outside corners the same fasteners can be used in all six holes. To avoid torsional stresses it is recommended as a rule of thumb to avoid threaded fasteners. Threaded fasteners can “lock-in” stresses. Also, threaded fasteners can loosen as the knuckle and lean steering rotates around the fastener. Using the above criteria there are two widely used candidates for the connections pins in this assembly.

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Figure 3R: Shoulder Bolt29

As shown in Figure 3R, a shoulder bolt has a smooth surface through the length of insertion, and then uses a nut at the tip of the bolt to hold it in place. A washer will also be needed of the fastener to separate the surface of the knuckle and lean steering from that of the nut.

Figure 4R: Clevis Pin w/Retainer29

A second possible fastener (Figure 4R) is a clevis pin. Like a shoulder bolt a clevis pin is smooth throughout the length of the insertion, but is not held in place by a nut. A clevis pin is held in place by a retainer. Retainers come in a number of sizes and shapes. However, a clevis pin can not be tightened to dimension, which could allow vibrations to occur. Consequently, the allowable tolerance of the lean steering and knuckle would have to be small.

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REAR FRAME (Robert Workman) The rear frame will be made out of the same material as the Y frame; 1.5” OD/ 1.25” ID tubing of 6061 T6 aluminum. The pieces will be cut with slandered band saw and then milled to proper angles and curves. To do this, fixtures will be need to maintained consistency between parts. A fixture will also be needed to weld the pieces together at the correct angles. After welding the rear frame together, a heat treatment must be done to return the welded joint back to a T6 state.

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FRONT KNUCKLE (Jeremy Lewis) The focus of this section of the DFMA report is to highlight the DFMA applied to the front knuckle component of Team 6’s design. As can be seen in the system drawing in Figure J1 below, the front knuckle is the small yellow component connecting the rear frame (green) and the y-frame (red). The purpose of the front knuckle is to act as the point of rotation for the rear frame and also to transfer loads between the two subsystems. It is a critical component to the design as it affects the overall performance of the vehicle as well as directly influencing rider safety. These two considerations necessitate proper design and application of a proper factor of safety. Although the general concern is to make this piece lightweight, cost effective, and aesthetically pleasing, structural integrity must remain the top priority.

Figure J1: Overall system view showing front knuckle followed by detail view of front knuckle The following paragraphs and figures proceed through the process of applying DFMA to the front knuckle from conceptual design to the current final design and onto a preliminary exploration into casting.

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Conceptual Design The conceptual design for the front knuckle is seen in FigureJ2 below. There were several problems with the conceptual design such as an unnecessarily complex geometry, excessive material, and many machining steps required for it to be produced. These issues were subsequently addressed in the successive designs as will be seen below.

Figure J2: Front Knuckle Conceptual Design

Initial Design The initial design of the front knuckle is seen in Figures J3 and J4 below. The features included were a post that would slip into the inner diameter of the front frame tube, a hole for the pin which the rear knuckle will rotate around, and a slot that the rear knuckle will fit in. Once this design was drawn and analyzed, DFMA was applied. Through DFMA it was seen that the front post would be extremely time consuming and in effect costly to machine. This realization led to the second iteration of the design which will be discussed in the following sections.

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Figure J3: Initial Design Figure J4: Initial Design VM Stress Second Iteration of Design Figures J5 and J6 below show the second iteration of the front knuckle design and its resulting Von Mises stress from applying FEA. The main change from the previous iteration is the replacement of the solid post with a hole which fits to the outer diameter of the Y frame tube. This design is much easier to machine as well as providing for a self locating assembly. Another advantage of this iteration is a reduction in weight.

Figure J5: Second Iteration of Design Figure J5: Second Iteration VM Stress Third Iteration (from U-Channel) The third iteration of the front knuckle is shown in Figure J6 below. The purpose of this iteration was to simplify the geometry to eliminate the complication of producing the large radius on the rear of the knuckle. In order to accomplish this, the rear face was left flat. This allows the use of a standard U-channel as can be seen in Figure J8. Using a prefabricated U-channel would greatly simplify the manufacturing of the knuckle. Main processes would include cutting a section of the channel to length, milling the front angled hole and drilling the pin hole to size.

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Figure J6: Third Iteration of Front Knuckle Figure J7: Third Iteration VM Stress

Figure J8: Standard U-Channel

First Iteration of Design for Casting Due to the complex geometry required for this component, casting presented itself as a cost effective alternative to machining. The first iteration of a cast front knuckle is seen in Figure J9 and Figure J10 below. Several benefits are offered by casting such as those mentioned above as well as greatly increased aesthetics. These benefits translate to a significant increase in value with a likely decrease in cost. Further research and analysis will be performed as well as discussion with a resident expert in manufacturing processes, in order to decide which method would be the best option for the final design of the front knuckle.

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Figure J9: Casting Iteration 1 Figure J10: Casting Iteration 1 VM Stress Representation of Casting A conceptual representation of the system for casting the front knuckle is seen in Figure J11 below. One will notice that this iteration of the front knuckle is a simple design with smooth radii with an acceptable nominal diameter in order to facilitate casting with common methods. As seen in Figure J11 the knuckle could be oriented with the front surface in the up position, with feeder and riser oriented as shown. This component is also small enough to facilitate being cast in batches for increased productivity.

Figure J11: Conceptual Representation of Casting System Conclusion

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TableJ1 below highlights the parameters by which each of the iterations was judged and compared. Each progressive iteration reduces the overall weight of the component and also the cost which is required to produce it. Although the Von Mises stress goes up with the reduction in overall material, the final designs are still well within the safe range. The yield strength of 6061 T6 Aluminum is 40ksi. The stress seen in the casting iteration 1 is 5815.8 psi. The minimum factor of safety specified for each component in the overall system is N = 3. With this factor of safety and Von Mises stress the front knuckle is still well within a safe limit when using 6061 T6 Aluminum. More research will be done to see if further optimization is possible and whether casting will be feasible. Table J1. Optimization Comparison Table Part Name Conceptual

Design Iteration 1 Iteration 2

DFMA applied. Iteration 3 U-channel

Casting Iteration 1

Total Weight .627 .793 .565 .6 .4

% Wt. Reduction (- indicates weight increased)

NA -26.5% 9.88% 4.30% 36.2%

V.M. Stress (psi) NA 1197.8 3652.7 2005.9 5815.8

Manuf. Proc. many Time consuming

4 3 3

As for further manufacturing and assembly considerations for this part a few operations will be performed. As mentioned previously the pin hole will be drilled or bored to the correct diameter and alignment. The front hole dimension is not as critical, and proper sizing may be obtained directly from the casting. This is due to the necessity for a small beveled gap between the tube and casting to allow proper penetration of the weld. Once the subsystem components are welded together and heat treated a surface treatment such as bead blasting or shot peening may be applied. Once the surface finish is adequate the parts will be anodized through electrolysis and dyed a certain color. This anodizing and dying process will not only add corrosion resistance but also a vibrant color which both add significant value to a consumer product.

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REAR KNUCKLE (Jason West)

The original design of the rear knuckle for the connection of this vehicle’s front frame to rear frame is shown below in Figure J1. This original design was created without much consideration for DFMA principles. For example it has two rounded protrusions on the left hand side that would be quite difficult and costly to manufacture. There is no added benefit to making these protrusions for connecting the rear frame; however, there is a considerable added manufacturing cost for producing a part with this geometry. Also, these protrusions would have to be welded to the rear frame without any amount of self-location available. This design would make the assembly of the rear knuckle and the rear frame difficult to align and weld together. Furthermore, there are unnecessary curvatures to the right side of the part that were included for clearance purposes. These curvatures would add manufacturing cost without adding value to the part because the front knuckle clearance could be made just as easily by using a simple chamfer.

Figure J1: Original Design of Rear Knuckle

Figure J2, shown below, represents the second iteration of the rear knuckle. This part includes a chamfer rather than complicated round on the right hand side to allow for clearance of the front knuckle. Also, instead of protrusions on the left side of the part, there are now two cutouts where the bars from the rear frame will attach. These round cutouts will be much easier to manufacture than rounded protrusions through any number of manufacturing methods. For example, since this rear knuckle will be a cast part, these cutouts can just be included in the casting process or cutout afterwards with a simple milling operation. These cutouts also allow for the rear frame to be easily located and welded to the rear knuckle. It is very important for the overall assembly of the vehicle that parts can be easily located for welding.

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Figure J2: Second Iteration of Rear Knuckle

Figure J3, shown below, represents the third iteration of the rear knuckle. In this modified part, the geometry was changed slightly in order to ensure that the self-locating cutouts no longer intersected each other. It can be seen in Figure J2 that the two rounded cutouts intersected each other slightly. This severely weekend the part as was seen when an FEA analysis of the part was performed. Also, these cutouts were made deeper in the third iteration to allow for better location of the rear frame. The cutouts were originally only 0.10 inches deep, which leaves very little room to locate and weld the part to the rear frame. If a small amount of debris were to be stuck in these cutouts it would make it difficult to properly locate the rear frame. Therefore, the depths of the cutouts were increased to 0.40 inches. A chamfer on the right side of the part is still included to ensure proper clearance for the front knuckle. Also, because this part passed an FEA stress analysis with very low overall stresses and deflections, the pin hole was moved towards the center of the part so that a considerable amount of material could be removed to reduce the overall cost and weight of this part.

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Figure J3: Third Iteration of Rear Knuckle

Figure J4 illustrates the final FEA analysis of the rear knuckle. This analysis was performed with a final mesh size of 60%, and after comparing it to previous Algor models with larger meshes; it was shown that the maximum stress converged at 1485.6 psi. Even after removing excess material from the part, this maximum stress is still well below the yield stress of Aluminum-6061 T6.

Figure J4: FEA Analysis of the Final Rear Knuckle Iteration

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Y – FRAME (Benjamin Kortz)

SUBSYTEM There were many decisions that were made in order to design the Y-frame portion of the vehicle for manufacturability. This portion of the vehicle serves as the direct supporter of the rider. If the Y-frame fails to withstand the stresses (statically and dynamically) of the rider and the storage compartment, then the entire system is unsafe. The Y-frame also serves as the center point of many other components. The steering column, the seat, the storage compartment, and the connection to the rear portion of the frame are all things that attach to or directly interact with the Y-frame. All of these other components therefore rely on the stability and effectiveness of the Y-frame. In order for this part to perform the required tasks, it must be manufactured consistently and reliably. COMPONENTS The Y-frame will be constructed of hollow thin walled 6061-T6 Aluminum tubing. There will be three pieces: a seat under-bar, a main support, a head tube casing, and a connecting support bar. Figure 1 below points out where these particular pieces are located with respect to the assembly.

Figure 1: Schematic of Y-frame components.

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MANUFACTURING CONSIDERATIONS One consideration that has to go into the manufacturing processes performed on this part is the compatibility it has with the other subsystems of the vehicle. This has to do with the specific angles and geometry of the frame. Before the connection knuckle and head tube can be designed, the Y-frame has to be tested under the loading conditions to identify an optimal design. This therefore requires the statics of the system to be performed. Once the system free body diagrams were completed, and the applied loads and constraints were identified, the Y-frame’s geometry and arrangement of its component parts was decided. When all of these steps were completed, finally the other parts of the system that interact with the Y-frame could be designed. Another manufacturing consideration that was identified has to do with minimizing the processes necessary to make the part. There was one major design feature of this part that was modified in order to optimize the manufacturability of this part. Figure 2 shows the initial design versus the finalized one. In the initial design a solid block of steel was to be machined to accommodate the gap between the under-bar and the main supports. This connecting bar served its purpose in that it absorbed and dissipated stresses within the system. It did not however allow for an optimal manufacturing process. By changing this component to a piece of the same bar stock that the rest of the frame is made of, many problems were solved. It meant that instead of ordering a separate geometry of material to be machined, a longer piece of bar stock could be ordered and from it the connecting support can be cut. Another manufacturing issue that was resolved with this change was the amount of waste produced from machining. In the initial design, extra manufacturing costs are necessary to machine away material, which also costs money. In the new process, only simple band saw cuts and notching is necessary. These are processes that are already in place, and included in the overhead costs of a factory.

Figure 2: Initial design with curved solid connecting bar(left), and final design with

straight bar stock connecting bar(right) optimized for manufacturing.

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STANDARD WORK OPERATIONS The following is a sequential list of operations that would be performed in manufacturing the Y-frame. These operations are subject to change based on complications and/or improvements found when the prototype vehicle is assembled. Band Saw: Three pieces need to be cut on a band saw from a single piece of bar stock. The lengths of each piece are 5.5 inches for the head tube casing, 7.5 inches for the connecting support bar, 14.5 inches for the seat under-bar, and 31.5 inches for the main support bar. Mill Notches & Face off: Each piece will have to be notched, or faced off in order to be fit together for a weld. Below is a picture to demonstrate what these notches will look like. Each piece that is to be notched will have to go into a fixture that sets the piece at the necessary angle. The main support bar will be notched on the head tube end, and faced off on the knuckled end. The seat under-bar is notched in order to fit around the main support, and the connecting support bar is notched on both ends.

Figure 3: Example of notch that is to be cut in to 3 pieces of the Y-frame assembly.

Jig Setup & Weld: This step will involve inserting all four pieces into a welding jig, and then making the welds to connect each piece. Research is still being done to figure out if welding collars are available for the particular angles that our components will be located. This operation will require the most skilled worker for this part’s manufacturing steps. Heat Treat: The welded bike frame will now undergo a heat treatment process to return the tempered material properties to the welded areas of the frame. This process is not labor intensive, and won’t require a skilled worker.

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Quality Inspection: After returning from heat treatment, the frame can be inspected. The length of the main support bar, as well as the seat under-bar can be measure to ensure their lengths are correct. Secondly the angles of each bar with respect to the other bars can be checked. A last inspection criterion is the quality of the weld. If all of these dimensions are good, then the part is ready to head onto the assembly operations.

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STORAGE (Muhammad Fahmi Ibrahim)

Initial Design Designing storage not only requires engineers to take into account the functionality, ease of use and load requirement of the product, but also the manufacturing and assembly processes. This is important to ensure the manufacturability of the product. Team 6 outlines storage requirements and any necessary changes to the design must meet these requirements. The requirements are:

• Weather protected • Able to sustain 35lb load • Lockable • Lightweight • Aesthetically-pleasing • No bigger than 12”x8”x18” dimension-wise • Has cushioned laptop compartment

With these in mind, a preliminary design has been made by Chris Keegan. The design has been made to be weather protected, lockable, and fit the required dimension (figure 1).

Figure 1: Preliminary Design

Based on this design, future refinement and iteration were done to meet other requirements. Load and lightweight requirements can be met by varying the material used, designing the product to use less material, and analyzing the storage in FEA to detect the weakest part and strengthen the part accordingly.

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Figure 2: First Iteration

First iteration of the design is made to meet other requirements such as lightweight, able to sustain 35 lb load, has padded laptop compartment and is aesthetically-pleasing. Figure 2 shows the design with the front compartment designed to use less material by using aluminum mesh supported with curved rigid plastic sheet. Another thin transparent plastic film is attached to the backside of the mesh to protect the storage from unpleasant weather condition.

Figure 3: Laptop Compartment

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Padded laptop compartment can be seen in figure 3. Standard medium sized laptop size is used (11” x 15” x 1.5”) to determined the compartment size. Soft rubber foam padding is glued on the compartment wall to provide shock absorber to the laptop. The laptop partition is made solid, unlike the front storage with aluminum mesh wall, in order to secure the laptop from being easily stolen. For the load requirement, FEA analysis is needed to be done in order to locate the weakness of the part and determine the maximum load it can with stand. Acrylonitrile Butadiene Styrene (ABS) plastic, Polyvinyl Chloride (PVC) plastic, and Aluminum 2024-T4 will be compared to find the right balance of cost, weight and maximum load the storage can handle. Table 1 provides a full comparison between the three materials.

Table 1: Material Comparision Material Weight

(lb) Maximum Load (psi)

Maximum Displacement

(in)

Cost (per in3)

Total cost*

ABS – Medium Impact 7.654 117.3 0.0067 $0.32 $65.80 PVC 10.35 110.4 0.0059 $0.94 $194.47 Aluminum 2024-T4 20.68 114.7 0.0002 $0.61 $125.92 *Volume = 206.9 in3 From table 1, medium impact ABS plastic shows an acceptable value for the maximum load and displacement it can yield; but significantly cost less than the other two materials and at the same time weigh the least. This proves to be the best material for the storage. However, the total cost of material is too high for a storage, while the maximum load is far from maximum stress the material can handle (ABS yield strength = 4290 psi30). Second iteration is needed in order to reduce the material cost even further. The thickness of the wall is reduced from ¼” to 1/8”, but the connection bars thickness is slightly increased to ½” and the connection points between the bars and the main storage are chamfered to handle the stress caused by the load. Final material information (figure 5) can be found in table 2.

Table 2: Final material data Material Weight

(lb) Maximum Load (psi)

Maximum Displacement (in)

Volume (in3)

ABS – Medium Impact 5.301 114.62 0.0077 143.3 The values are still within acceptable values. The factor of safety of the storage is 386, much higher than the required 3 and the total material cost has been successfully reduced to $45.

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Figure 4: FEA Analysis

Figure 5: Initial Design

After further feedback from peers and advisors, some minor issues of the design are noted — mainly the laptop compartment and plastic mesh. After further analysis, laptop compartment is unnecessary as it makes the manufacturing process complicated and can simply be replaced with Velcro strap. Furthermore, the complexity in manufacturing the plastic mesh outweighs its functions – reduce weight and provide aesthetic value – and therefore, this functionality will be dropped in the final design. Other minor change that has been made to the final design is the simplification of the storage curvature for easier

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plastic molding injection process. There’s no need for further FEA analysis since the addition of the material will only strengthen the part, not weaken it.

Figure 6: Final Design

Parts ABS – Medium Impact: 0.125 inch thick x 142 in² Polyethylene foam: 798 in² 2” plastic hinges: 2 pieces Steel hasp latch: 1 set Lockpad: 1

Design for Manufacturing Since the storage is mainly made out of plastic, plastic processing techniques will be considered. In previous design process, the components manufacturability was also considered. Some of the considerations were:

1) No complex shape or extrusion 2) Parts should be able to weld easily 3) Details should be big and easy to manufacture

Although some basic considerations were done, plastic processing techniques itself are needed to be researched on, so better assumptions can be made to the design in order to reduce the complexity of the manufacturing process. By researching the processes, the knowledge gain can be applied to design process so that the material used can

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maximized, manufacturing time can be decreased and the efficiency of the manufacturing can be increased. After researching various plastic processing methods, some of the processes were identified that suits best to produce the storage parts. The components will be further refined and re-designed around the processing techniques so that they can be applied effectively.

Figure 7: Parts - Clockwise: lid, main compartment, connection bars

There are four separate components (figure 6) to be manufactured and each of them employs different processing technique. Each of the components manufacturing process will be explained in detail.

Injection Molding

Main Compartment The main compartment is basically an extruded square box with an open end. There are two techniques were considered to manufacture this part: injection molding and injection

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blowing molding. Injection molding main strengths are its compatibility with the material used31, ABS, its high production rates and cheap mass-production process32. However, injection blowing molding is suitable for container products. After further research, injection blowing molding requires the product to be blown by air (like bottles) and this is not necessary for the main compartment. Figure 7 shows a rough sketch of the injection molding process with the main compartment mold being used. The process is explained below:

Figure 8: Injection molding

1: The material fills via gate and being pushed by the screw through runner. 2: The material fills the mold. 3: Ejector bar pushes the finished product off the mold231 above. In the initial design process, the manufacturing capabilities were taken into account in setting the wall thickness. The wall thickness wasn’t being reduced even further although the maximum load is far lower than its yield strength because such thickness might not able to be manufactured accurately. Since the tight tolerance of injection blowing is around ±0.1~0.5 mm, the wall thickness of 0.125” or 3.175 mm can be manufactured without sacrificing its accuracy and therefore the earlier assumption is correct.

Extrusion

Connection bar Both of the connection bars are relatively easy to manufacture. A square extruded bar that match its dimensions can be bought from supplier or the bar can be extruded in-house. Buying the bar from supplier is a cheaper option than having to buy the extrusion machine and extrude the part internally. This is because, not only the supplier can manufacture the parts at higher production rates and thus reduce the cost down, extruding the parts in-house for 5000 units is not economical since the batch produced is too small to cover the overhead cost.

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Plastic Cutting

Lid The lid doesn’t serve any purpose other than to protect the storage from weather and intruders. Therefore, there is no need to design the lid in intricate shape. In manufacturing process, the simple shape of the lid can reduce the time and cost needed to manufacture the part. By choosing the right saw blade for cutting ABS plastic, the part can be easily cut and manufacture. Laser cutting can also be used in this process to yield cleaner and more accurate result. Both techniques can employ CNC machine to make the process automatic and has higher accuracy.

Foam Unlike lid, cutting foam is much easier as it has very low material hardness and any cutter or knife can be used to cut it into the desired shape.

Design for Assembly Reducing the components needed to be manufactured to three parts might complicate the manufacturing process; however it makes assembly process much easier and quicker. There are five parts to be assembled in five steps (figure 9):

Figure 10: Step-by-Step Assembly

1. Weld connection bars to the main compartment

2. Attach foam to the inside of the main compartment.

3. Join latches and hinges to the lid.

4. Attach hinges from the lid to the main compartment.

5. Attach Velcro strap inside of the compartment

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Mechanical Fastening Latches and hinges can be attached to the lids, grill and main compartment using mechanical fastening because of compatibility issue in welding and adhesive bonding. Holes can be made in the lid and the main compartment and the parts can be connected using bolts and nuts. Washers must be inserted in between of the bolts and nuts, and the parts at all time in order to protect the plastic from wearing. Holes should be made on the lids and the grill in order to install the latches and hinges properly. The holes should be made before the grill and the main compartment welded together to make the drilling process easy. Since the holes locations are on the easy to reach place, there’s no need to redesign the holes.

Final Design After analyzing manufacturing and assembly processes, final design can be made using the recommendations outlined previously. Since most of the considerations taken while designing the initial design were validated in the manufacturing and assembly design processes, only some changes are needed to be done. The changes are:

1) Aluminum mesh to polyethylene mesh. 2) Plastic hinges material is known, polyethylene. 3) Holes are made on the lid. 4) Increase connection bar thickness to ½”. 5) Chamfered the connection bars to the wall of the main compartment.

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Figure 9: Final Design

Parts & Material Costs These are the parts that are required to assemble the full product: ABS – Medium Impact (pellets): 3.48 lb ($7.14) ABS – Medium Impact bar stock: .75” x 2” x 9” ($5.51) Polyethylene foam: 798 in² ($6.53) 2” Polyethylene hinges: 2 pieces ($4.36) Steel hasp latch: 1 set ($1.00) Lock: 1 ($5.50)

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Appendix E: Failure Modes and Effects Analysis See attached file: FMEA.xls The purpose of failure modes and effects analysis is to identify all possible modes of failure that may occur, and then find the root cause of why the failure occurred. Below some of the most severe and most probable failures are discussed in detail, including the reasons they may occur and what steps were taken to avoid such failures. Failure: Frame Fracture / Yielding Severity: 5 Probability of Occurrence: 2 Table 3: Five-Why's Analysis of Frame Fracture and Yielding

Why 1 Why 2 Why 3 Why 4

load higher than estimated

Vehicle weight is greater than predicted

Material used for design is heavier than expected

Poor estimation by designers

Motor and batteries

weigh more than expected

Different motor/batteries used then expected

Rider and/or cargo exceed predicted

weights

Dynamic loading higher than predicted

material properties different than estimated manufacturing defects

welded areas are weaker than material properties Poor welding Inexperienced welders

The material was not re-tempered after welding

geometry design Design does not distribute forces well

Not enough benchmarking and design taken into

consideration

incorrect FEA parts were not constrained properly

Difficult to analyze complex vehicle in

Algor

Inexperience with FEA analysis

Impact/accident vehicle not designed for

certain impacts and accidents

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Table 1 shows the “Five-Why’s” analysis of frame fracture and yielding. In this case, most of the failure modes digress to a design failure having to do with poor estimation and analysis. To ensure that a lack of design experience would not result in fracture or yielding, a high factor of safety was used throughout the product. A tradeoff to this higher factor of safety was that the frame may end of being heavier than needed. The team decided that a small increase in weight was worth an increase in operator safety. Failure: Inoperable Motor Severity: 4 Probability of Occurrence: 3 Table 4: Five-Why's Analysis of an Inoperable Motor

Why 1 Why 2 Why 3 Why4

no current improper controller mismatch controller

damage to controller poor mounting location

water damage wasn't protected from moisture

short in the system bad connections

poor wiring

corrosion contacts weren't protected

battery failure failed to charge

failed to hold charge

mechanical failure bearing failure over heat poorly maintained

brush failure poor quality product

over heat bearing failure poorly maintained

too much current controller failure

too much load inadequate motor size

Table 2 shows the “Five-Why’s” analysis of an inoperable motor, a case of high severity and probability, due to the number of ways the motor could fail and that such a failure would make the vehicle much more difficult to operate. Many of the possible failures had to do with poor wiring and controller malfunctions. To address the wiring issue, the motor that was chosen is available with weather proof wiring and connections. Also, the wires will be kept very close to the frame so that they are not accidentally torn from the correct connections. The controller will also be mounted in a location to avoid contact in the event of an accident. Mechanical failure is somewhat out of the team’s control, and is more dependent on the motor manufacturer. Background research was completed on the company from which the motor will be purchased, and a warranty is also available.

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Failure: Brake Failure Severity: 4 Probability of Occurrence: 3 Table 5: Five-Why's Analysis of Brake Failure

Why 1 Why 2 Why 3 Why 4

Overheating Vehicle exceeds inertial limit

Vehicle is heavier than expected Too much cargo

Rider over estimated weight

Stopping from very high speeds

Need to stop coming down a hill

Rider pedals hard and is using full electric assist and suddenly

needs to stop

Not enough time for cool down between

stops Stop and go traffic

brake pads wear out

Brake cables stretched out

Lack of general maintenance

Rider lacks griping ability to provide

ample braking force

Miscalculation in required force

Overestimation of "normal" gripping

ability

Table 3 shows the “Five-Why’s” analysis of brake failure, another case of high severity and probability, due to the safety concern of not being able to stop and that brake systems are complex, which allows for more modes of failure. Some of the failure modes come down to the fact that extreme conditions may not have been taken into consideration during design. For this reason, Team 6 took a high factor of safety when performing brake calculations. Also, the front and rear brakes are fully independent and redundant so that even if one system fails, the other should still be operable. Another safety precaution was to put brakes on both rear wheels. This increases the surface area where the brake pads grip the rim and in doing so increase the overall braking force. Another common reason the brakes might fail is due to improper maintenance of the brake cables and pads. To help combat this, the user manual will have specific instructions on how to diagnose these problems before they cause an accident and suggest a timeline of how often to change these components.

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Appendix F: Cost Estimation FRONT KNUCKLE

Operation Operation 1 Operation 2 Operation 3

Cut U channel to

length

Drill and bore pin joint hole through front

knuckle

Inspection, cleanup, etc. for the 8 hour

shift

total time to complete operation(s) in hours 0.05 0.25 0.1 labor rate for operation $12.00 $15.00 $12.00 labor cost = (3 x 4) $0.60 $3.75 $1.20 basic overhead factor 1 1 1 equipment factor 0.5 0.5 0.5 special operation / tolerance factor 0 0.25 0 labor / overhead / equipment cost = 5 x (6 + 7 + 8) $1.50 $10.31 $3.00 purchased materials / component costs $1.50 $0.00 $0.00 Sum of total costs $16.31

REAR KNUCKLE

Operation Operation 1 Operation 2 Operation 3

Cast entire rear knuckle part besides

pin hole

Drill and bore holes through rear knuckle

Inspection, cleanup, etc. for the 8 hour

shift

total time to complete operation(s) in hours 0.5 0.25 0.1 labor rate for operation $20.00 $15.00 $12.00 labor cost = (3 x 4) $10.00 $3.75 $1.20 basic overhead factor 1 1 1 equipment factor 0.5 0.5 0.5 special operation / tolerance factor 0 0 0 labor / overhead / equipment cost = 5 x (6 + 7 + 8) $25.00 $9.38 $3.00 purchased materials / component costs $2.10 Sum of total costs $39.48

122

REAR FRAME Operation Operation 1 Operation 2 Operations 3 Operation 4

Cut bar stock to length per specifications and face-off

ends

Place parts in fixtures and weld together

Inspection and clean,

etc. Paint

total time to complete operation(s) in hours 0.03 0.17 0.1 0.08labor rate for operation $12.00 $15.00 $12.00 $12.00labor cost = (3 x 4) $0.36 $2.55 $1.20 $1.00basic overhead factor 1 1 1 1equipment factor 0.5 0.5 0.5 0.5special operation / tolerance factor 0 0 0 0labor / overhead / equipment cost = 5 x (6 + 7 + 8) $0.90 $6.38 $3.00 $2.50purchased materials / component costs $7.32 Sum of total costs $20.10

123

Y FRAME Operation Operation 1 Operation 2 Operations 3 Operations 4

Band saw to length bar

stock of pipe

Machine/mill notches

Jig setup for welding Weld

total time to complete operation(s) in hours 0.03 0.25 0.08 0.17labor rate for operation $12.00 $15.00 $15.00 $15.00labor cost = (3 x 4) $0.36 $3.75 $1.20 $2.55basic overhead factor 1 1 1 1equipment factor 0.5 0.5 0.5 0.5special operation / tolerance factor labor / overhead / equipment cost = 5 x (6 + 7 + 8) $0.90 $9.38 $3.00 $6.38purchased materials / component costs $98.28

Operation Operations 5 Operations 6

Heat treat welded parts

Dimensional check, quality

inspection

total time to complete operation(s) in hours 0.08 0.1

labor rate for operation $12.00 $12.00 labor cost = (3 x 4) $0.96 $1.20 basic overhead factor 1 1 equipment factor 0.5 0.5 special operation / tolerance factor 0.25 labor / overhead / equipment cost = 5 x (6 + 7 + 8) $2.64 $3.00

purchased materials / component costs Sum of total costs $123.57

124

LEAN STEERING Vertical Support

Operation Operation 1 Operation 2 Operation 3 Operation 4

Cut tube to correct length

Hole Cutting (top and

bottom hole)

Clearance material

removal (top and bottom)

Quality check for

measurements

total time to complete operation(s) in hours 0.03 0.1 0.1 0.1labor rate for operation $12.00 $12.00 $12.00 $12.00labor cost = (3 x 4) $0.36 $1.20 $1.20 $1.20basic overhead factor 1 1 1 1equipment factor 0.5 0.5 0.5 0.5special operation / tolerance factor 0 0 0 0labor / overhead / equipment cost = 5 x (6 + 7 + 8) $0.90 $3.00 $3.00 $3.00purchased materials / component costs $2.62 Sum of total costs $12.52

Cross Bar

Operation Operation 1 Operation 2 Operation 3 Operation 4

Cut tube to correct length

Hole Cutting (top and

bottom hole)

Clearance material

removal (top and bottom)

Quality check for

measurements

total time to complete operation(s) in hours 0.03 0.1 0.1 0.1labor rate for operation $12.00 $12.00 $12.00 $12.00labor cost = (3 x 4) $0.36 $1.20 $1.20 $1.20basic overhead factor 1 1 1 1equipment factor 0.5 0.5 0.5 0.5special operation / tolerance factor 0 0 0 0labor / overhead / equipment cost = 5 x (1 + 6 + 7 + 8) $0.90 $3.00 $3.00 $3.00purchased materials / component costs $3.13 Sum of total costs $13.03

125

Fork Operation Operation 1 Operation 2 Operation 3

Cut tube to

length Bend tube Cut holes

total time to complete operation(s) in hours 0.03 0.1 0.1 labor rate for operation $12.00 $15.00 $12.00 labor cost = (3 x 4) $0.36 $1.50 $1.20 basic overhead factor 1 1 1 equipment factor 0.5 0.5 0.5 special operation / tolerance factor 0 0 0 labor / overhead / equipment cost = 5 x (1 + 6 + 7 + 8) $0.90 $3.75 $3.00 purchased materials / component costs $11.62 Operation 4 Operation 5

Cut notches

Quality check for

measurements total time to complete operation(s) in hours 0.1 0.1 labor rate for operation $15.00 $12.00 labor cost = (3 x 4) $1.50 $1.20 basic overhead factor 1 1 equipment factor 0.5 0.5 special operation / tolerance factor 0 0 labor / overhead / equipment cost = 5 x (1 + 6 + 7 + 8) $3.75 $3.00 purchased materials / component costs Sum of total costs $26.02

Total Cost of Lean Steering: $91.00

126

STORAGE Operation Operation 1 Operation 2 Operation 3

Molding Plastic Frame

Attach mesh plastic to the

grill

Connect grill to the main

compartment. total time to complete operation(s) in hours 0.2 0.1 0.1 labor rate for operation $12.00 $12.00 $12.00 labor cost = (3 x 4) $2.40 $1.20 $1.20 basic overhead factor 1 1 1 equipment factor 0.5 0.5 0.5 special operation / tolerance factor labor / overhead / equipment cost = 5 x (6 + 7 + 8) $3.60 $1.80 $1.80 purchased materials / component costs $52.15 $1.70 $6.53

Operation Operation 4 Operation 5 Operation 6

Weld connection bars to the

main compartment

Join latches and hinges to

the lid.

Attach hinges from the lid to

the main compartment.

total time to complete operation(s) in hours 0.5 0.1 0.1 labor rate for operation $15.00 $12.00 $12.00 labor cost = (3 x 4) $7.50 $1.20 $1.20 basic overhead factor 1 1 1 equipment factor 0.5 0.5 0.5 special operation / tolerance factor labor / overhead / equipment cost = 5 x (6 + 7 + 8) $11.25 $1.80 $1.80 purchased materials / component costs $6.00 $2.06 Sum of total costs $67.58

127

SUMMARY Component Cost

Cruz Bike 300.00 Hub Motor 258.40 Y Frame 123.57

Lean Steering 90.62 Front Knuckle 16.31 Rear Knuckle 39.48 Rear Frame 20.10

Storage 67.58 Miscellaneous Components 80.00

Total 1000.00

128

References 1 “National Energy Policy”. National Energy Policy Development Group.

http://www.ne.doe.gov/pdfFiles/National-Energy-Policy.pdf , November 10, 2006. 2 Beating High Energy Prices. http://www.energy.gov/3464.htm , November 9, 2006 3 Kremer, Greg, and Urieli, Israel. “Needs statements – v1”. September 21, 2006.

https://blackboard.ohiou.edu/webapps/portal/frameset.jsp?tab=courses&url=/bin/common/course.pl?course_ id=_12569_1.

4 http://en.wikipedia.org/wiki/Analytic_Hierarchy_Process, 2006, Accessed October 14, 2006. 5 http://www.cpsc.gov/BUSINFO/regsumbicycles.pdf, 2002, Accessed March 11, 2006. 6 "Walkways and Bikeways." AFCEE. 1998. Air Force Center of Environmental Excellence. 11 Mar. 2007

<http://www.afcee.brooks.af.mil/ldg/s10WalkBike/c04BikeGuide.html>. 7 Whittaker, Ronald W., “Electric Bicycle”, US Patent no. 6,155,369, December 5, 2000. 8 Chou, Wen-Cheng, “Electrical Bicycle”, US Patent no. 5,433,284, July 18, 1995. 9 Turner, James R., “Electric Bicycle and Methods”, US Patent no. 6,629,574, October 7, 2003. 10 http://greenspeed.us/machine-x_zvo-bike.htm 2005 Electric Cyclery; Date Accessed 10/5/2006. 11 http://www.werelectrified.com/electric_bikes.html 2003 We’re electrified; Date Accessed 10/5/2006 12 http://egovehicles.com/products/north-america/; eGo Vehicles, Inc.; Date Accessed: 10/5/06; Copyright 2006. 13 http://www.jvbike.com/recumbents/EZ-3_sx.htm; JV Bike Sales and Rentals Ltd.; Accessed 10/5/06;

Last Modified 12/26/2004. 14 http://en.wikipedia.org/wiki/Types_of_hybrid_vehicle. 2006, Accessed October 14, 2006. 15 Hybrid Synergy Drive System, http://www.toyota.com/vehicles/2007/prius/key_features/hsd.html,

retrieved November 3, 2006. 16 Munson, Bruce R., Donald F. Young, and Theodore H. Okiishi. Fundamentals of Fluid Mechanics. 5th

ed. Indianapolis, IN: Wiley, Inc., 2006. 17 Hayes “U”. An Introduction into Disc Brake Technology. Hayes Disc Brakes Company. Revised 2005.

Last Viewed 11 Nov 2006. [http://www.hayesdiscbrake.com/hayesu_product1.shtml] 18 “Benefits of Safety Through Design”. Institute for Safety Through Design. September 6, 2001. Accessed: February 4, 2007. http://www.nsc.org/istd/aboutus.htm 19 Christensen, W.C. & Manuele F.A. Safety Through Design. National Safety Council Press, Library of Congress. 20 http://tandem-fahren.de/Mitglieder/Christoph_Timm/Y-Foil.html, Accessed March 10, 2007. 21 “Lightfoot Cycles”. http://www.lightfootcycles.com/rrmodel.htm. 2007, Accessed February 21, 2007. 22https://trorderonline.thomasregister.com/itemdetails.aspx?az=71997001&cat=4388&origin=TROI&prof=142243&itemid=3762350&phid=05032008&search_type=ph&searchstring=, Accessed March 10, 2007 23 Urieli, Israel. "Human Power Vehicles." 22 Jan. 2005. Ohio University. 11 Mar. 2007

<http://www.ent.ohiou.edu/~et181/hpv/hpv.html>. 24 http://www.wildernessenergy.com, Accessed March 09, 2007 25 Buchmann, I. (2003, July). Can the lead-acid battery compete in modern times? Retrieved March 22, 2007, from Battery University : http://batteryuniversity.com/partone-6.htm 26 Protomold Company (2004). Design Tips for Rapid Injection Molding. Retrieved from: http://www.protomold.com/designtips/2004/2004-11_designtips/ on May 20, 2007 27 http://www.eere.energy.gov/; Accessed May 17, 2007. 28 http://www.whitehouse.gov/infocus/energy/, Accessed May 17, 2007. 29 "Bolts and Pins." 09 Mar. 2007 <www.mcmaster.com>. 30 Acrylonitrile Butadiene Styrene (ABS), Molded – Material properties. http://www.matweb.com/search/SpecificMaterial.asp?bassnum=O1100 31 Injection Moulding, retrieved from: http://www.bpf.co.uk/bpfindustry/process_plastics_injection_moulding.cfm 32 Alting, Leo. (1994). Manufacturing Engineering Processes, 2nd Edition. Pg. 353