HES4350 Mechanical System Design, Semester 2 2012, Project Report (3S Parking System)

Swinburne University of Technology (Sarawak Campus)

School of Engineering and Sciences

HES4350 Mechanical System Design

Smart, Safe & Sustainable (3S) Parking System

By

Stephen, P. Y. Bong (4209168)

Bachelor of Engineering (Mechanical Engineering)

Kueh Min Hui (4209974)


Ling Wang Soon (4203364)


Jimmy, H. L. Huong (4209761)


Wong Ting Lee (4227794)


Group 5

Due Date: 5th

December 2012 (Wednesday)

Lecturer: Dr. Soon Kok Heng

Abstract i

Abstract

The aim of this design project is to design and develop a 3S Parking System acts as an

parking alternative for household users who are confronted with problems of insufficient parking

spaces in normal housing area with confined parking spaces. Six distinct conceptual designs are

developed based on the needs and demands of customer. The best design is selected through the

evaluation of alternatives according to the customer attributes. Engineering analyses are

performed to ensure the employment of the product is free from the risk of harm, and finite

element analysis on the analytical prototype is conducted to check with the solutions obtained

from the manual calculations. The results manifested that the results obtained from manual

calculations are logic and the position where the maximum deflection occurred is as expected.

Hence, the minimum thickness of the platform as well as the minimum cross-sectional area of

scissor-lift legs is determined by the employment of maximum bending stress theory. In

conclusion, a 3S Parking System is successfully developed in which the demands and needs of

customers are satisfied.

Table of Contents ii

Table of Contents

Abstract ............................................................................................................................................ i

List of Figures ................................................................................................................................. v

List of Tables ................................................................................................................................. vii

1.0 Introduction ......................................................................................................................... 1

2.0 Identifying Opportunities .................................................................................................... 2

2.1 User Persona .............................................................................................................. 2

2.2 User Scenario ............................................................................................................. 2

2.3 Product Opportunity Proposal (Mission Statement) .................................................. 2

3.0 Clarifying Objectives........................................................................................................... 4

4.0 Function Analysis ................................................................................................................ 6

5.0 Customer Needs List ........................................................................................................... 8

6.0 Performance Specifications ............................................................................................... 10

7.0 Determining Characteristics .............................................................................................. 11

8.0 Concept Generation (Generation of Alternatives) ............................................................. 13

8.1 Concept A ................................................................................................................ 13

8.1.1 Operations .................................................................................................... 13

8.1.2 Weakness or Problems ................................................................................. 14

8.2 Concept B ................................................................................................................. 14

8.2.1 Operations .................................................................................................... 14


8.3 Concept C ................................................................................................................. 15

8.3.1 Operations .................................................................................................... 15


8.4 Concept D ................................................................................................................ 16

8.4.1 Operations .................................................................................................... 17


8.5 Concept E ................................................................................................................. 17

8.5.1 Operations .................................................................................................... 18


8.6 Concept F ................................................................................................................. 18

8.6.1 Operations .................................................................................................... 18


9.0 Concept Selection (Evaluation of Alternatives) ................................................................ 20

9.1 Concept Screening ................................................................................................... 20

9.2 Concept Scoring (Weighted Objectives Method) .................................................... 21

9.3 Concept Testing ....................................................................................................... 22

Table of Contents iii

10.0 Product Architecture .......................................................................................................... 23

10.1 Schematic of 3S Parking System ............................................................................. 23

10.2 Schematic of Clustered Elements ............................................................................ 24

10.3 Geometric Layout .................................................................................................... 25

11.0 Detail Design (Engineering Synthesis and Analysis) ........................................................ 26

11.1 Failure Modes and Effect Analysis (FMEA) ........................................................... 26

11.2 Detail Calculations ................................................................................................... 31

11.3 Load Analysis .......................................................................................................... 31

11.4 Selection of Hydraulic Cylinder .............................................................................. 37

11.4.1 Hydraulic Cylinder Calculations .................................................................. 40

11.4.2 Buckling of Piston Rod ................................................................................ 44

11.5 Selection of Material ................................................................................................ 46

11.6 Bending Moment and Deflection (Platform) ........................................................... 46

11.7 Bending Moment and Deflection (Scissor-lift Legs) ............................................... 53

12.0 Computer Aided Design (CAD) and Prototyping ............................................................. 56

12.1 Prototyping ............................................................................................................... 56

12.1.1 Analytical Prototyping ................................................................................. 56

12.1.2 Detail Drawings of 3S Parking System ........................................................ 61

12.2 Finite Element Analysis (FEA) ................................................................................ 64

12.2.1 Deflection of Platform .................................................................................. 66

12.2.2 Deflection Profile of Entire 3S Parking System .......................................... 67

13.0 Value Engineering ............................................................................................................. 69

14.0 Design for Manufacturing (DFM) ..................................................................................... 70

15.0 Safe Design ........................................................................................................................ 75

16.0 Discussion.......................................................................................................................... 77

17.0 Conclusion ......................................................................................................................... 78

18.0 Recommendations ............................................................................................................. 79

Acknowledgement ......................................................................................................................... 80

References ..................................................................................................................................... 81

Appendices .................................................................................................................................... 82

Appendix 1 – Project Plan and Execution (Gantt chart) ................................................... 83

Appendix 2 – Presentation PowerPoint Slides .................................................................. 91

Appendix 3 - Tables of Typical Properties of Selected Materials Used in Engineering . 103

Appendix 4 – Concurrent Engineering Write-up ............................................................ 104

Appendix 5 – Design for Manufacturing Exercises ........................................................ 108

Appendix 6 – Safe Design Case Studies and Exercises .................................................. 108

Table of Contents iv

List of Figures v

List of Figures

Figure 1: Objective Tree of 3S Parking System .............................................................................. 5

Figure 2: Block Diagram of 3S Parking System ............................................................................. 7

Figure 3: House of Quality for 3S Parking System ....................................................................... 12

Figure 4: Functional Diagram of 3S Parking System ................................................................... 13

Figure 5: 3D Sketch of 3S Parking System (Concept A) .............................................................. 14

Figure 6: 3D Sketch of 3S Parking System (Concept B) .............................................................. 15

Figure 7: 3D Sketch of 3S Parking System (Concept C) .............................................................. 16

Figure 8: 3D Sketch of 3S Parking System (Concept D) .............................................................. 17

Figure 9: 3D Sketch of 3S Parking System (Concept E) .............................................................. 18

Figure 10: 3D Sketch of 3S Parking System (Concept F) ............................................................. 19

Figure 11: Schematic of 3S Parking System ................................................................................. 23

Figure 12: Schematic of Clustered Elements ................................................................................ 24

Figure 13: Geometric Layout of 3S Parking System .................................................................... 25

Figure 14: Block Diagram of 3S Parking System ......................................................................... 27

Figure 15: Free Body Diagram (F. B. D.) of the Scissor-lift Mechanism during the Fully-lifted

Position .......................................................................................................................................... 32

Figure 16: Free Body Diagram (F. B. D.) of the Platform ............................................................ 33

Figure 17: Free Body Diagram (F. B. D.) for Leg 1 ..................................................................... 34

Figure 18: Free Body Diagram (F. B. D.) of Leg 3 ....................................................................... 35


Figure 20: Plot of Hydraulic Force, FCD (N) versus Angle, θ (Deg.) with Respect to the

Horizontal ...................................................................................................................................... 37

Figure 21: Selected Hydraulic Cylinder (Bosch Rexroth AG, 2003, p. 4) ................................... 38

Figure 22: Mounting Styles MP5 (Boshc Rexroth AG, 2003, p. 10) ............................................ 38

Figure 23: Selection of Hydraulic Cylinder (Bosch Rexroth AG, 2003, p. 5) .............................. 39

Figure 24: Schematic of Area, Force and Flows in the Hydraulic Cylinders (Bosch Rexroth AG,

2003, p. 6) ...................................................................................................................................... 41

Figure 25: Weight of Selected Cylinder (Bosch Rexroth AG, 2003, p. 7) ................................... 42

Figure 26: KK Values (KK = M48x2) (Bosch Rexroth, 2003, p. 11) ........................................... 42

Figure 27: CH Value of M48x2 (Bosch Rexorth, 2003, p. 28) ..................................................... 43

Figure 28: Value of Maximum Stroke (Bosch Rexorth, 2003, p. 3) ............................................. 43

Figure 29: Load Guidance Factor, K (Bosch Rexroth, 2003, p. 31) ............................................. 44

Figure 30: Maximum Stroke (Catalogue) (Bosch Rexroth, 2003, p. 30) ...................................... 45

Figure 31: Free Body Diagram (F. B. D.) of the Platform ............................................................ 47

Figure 32: Free Body Diagram (F. B. D.) of the Platform when the Lifting Mechanism is at

Fully-lifted position ....................................................................................................................... 47

Figure 33: Free Body Diagram (F. B. D.) of the Platform when the Lifting Mechanism is at

Fully-lowered Position .................................................................................................................. 50


Figure 35: 3D Model of 3S Parking System (Fully-lowered) ....................................................... 57

Figure 36: 3D Model of 3S Parking System (Fully-lifted) ........................................................... 57

Figure 37: The Single Acting Single Rod Hydraulic Cylinder ..................................................... 58

Figure 38: The Scissor-lift Mechanism (Lifting Device) used in 3S Parking System .................. 59

Figure 39: Fixed Ends of the Scissor-lift Mechanism ................................................................... 60

Figure 40: Roller of Scissor-lift Mechanism ................................................................................. 60

Figure 41: Backup Battery for 3S Parking System during Power Cut .......................................... 61

Figure 42: Top, Side, Front and 3D Isometric Views of 3S Parking System ............................... 62

Figure 43: The Exploded View of 3S Parking System ................................................................. 63

List of Figures vi

Figure 44: Methodologies of Finite Element Analysis ................................................................. 65

Figure 45: Deflection Profile of the Platform Obtained from SolidWorks FEA Simulation ........ 66

Figure 46: Side View of Deflection Profile of the Platform ......................................................... 67

Figure 47: Deflection Profile of the Entire 3S Parking System .................................................... 68

Figure 48: 5 Steps Approach ......................................................................................................... 70

List of Tables vii

List of Tables

Table 1: Product Opportunity Proposal (Mission Statement) for 3S Parking System .................... 2

Table 2: Essential Sub-functions with Their Corresponding Means to Achieve Them .................. 6

Table 3: The Interpretation of Customer's Statement Obtained from Online Survey ..................... 8

Table 4: Need Statement with Their Corresponding Importance and Hierarchy ............................ 9

Table 5: Targeted Product Specifications of 3S Parking System .................................................. 10

Table 6: Matrix of Concept Screening .......................................................................................... 20

Table 7: Table of Concept Scoring (Weighted Objectives Method) ............................................. 21

Table 8: Rating Scale for Various Concepts Listed in Table 6 & 7 .............................................. 22

Table 9: Failure Modes and Effect Analysis (FMEA) of Body for 3S Parking System ............... 28

Table 10: Failure Modes and Effect Analysis (FMEA) for Force Generator of 3S Parking System

....................................................................................................................................................... 29

Table 11: Failure Modes and Effect Analysis (FMEA) for Base of 3S Parking System .............. 29

Table 12: Failure Modes and Effect Analysis (FMEA) for Control System of 3S Parking System

....................................................................................................................................................... 30

Table 13: Magnitudes of Nomenclatures for the Lifting Mechanism at Fully-up Position .......... 47

Table 14: Magnitudes of Nomenclatures for the Lifting Mechanism at Fully-lowered Position . 50

Table 15: Magnitudes of Nomenclatures in Figure 10 .................................................................. 53

Table 16: Magnitude of Ay', J1 and F'CD at θ = 1.7 and 20.9 Degrees ........................................... 54

Table 17: Value Engineering for 3S Parking System ................................................................... 69

Table 18: Design for Manufacture ................................................................................................ 71

Table 19: Cost Reduction .............................................................................................................. 72

Table 20: Cost Reduction (Continued) .......................................................................................... 73

Introduction Page 1 of 78

1.0 Introduction

In pace with the progressive of advance technologies, rapid economic growth as well as

urban development nowadays, owing a car as a means of transportation is no longer a matter that

is unattainable. On the contrary, the excessive number of cars per household which results in the

problems of insufficient parking spaces in normal residential area is the matter that vexes the

household users nowadays. According to Noresah (2012, p. 65), the average motor registration

rate at Malaysia in 2012 is approximately 1.06 cars per person, in which also implies that one

household owns at least two cars and above which results in the dire demand of vacant spaces for

them to park their cars within the house compound. As the safety of cars cannot be ensured by

parking outside the house compound especially for those pricey cars, hence, consumers will opt

for other alternatives or solutions for it. Thus, with the current advanced technologies, the

solutions such as extension of existing house compound for the construction of new parking bays

or renovations will no longer be the last resort to the problem statement.

The primary intention of this project is to design and develop a Smart, Safe, and

Sustainable (3S) Parking System that acts as an aid for consumers who are confronted with

problems of insufficient parking spaces to park their extra cars in normal residential housing

compound that has confined parking spaces. Although there are few types of parking systems

being utilized as a solution to the problem statement exist in current market, however, the 3S

Parking System is something novel and innovative in which scissor-lift mechanism is employed

as a lifting device and the targeted customers are mainly household users. As mentioned above,

the main specs of the 3S Parking System is to generate more vacant spaces by optimizing the

conventional parking alternatives which practiced by most of the household users. As a result,

more cars can be parked within the house compound in which safety of cars can be guaranteed.

The utilization of 3S Parking System in normal residential housing area not merely

possesses the capability to provide more vacant spaces for household users, but instead also

ensure the safety of it with regard to the sustainability issue and practice. Target specifications of

product can be formed through the gathering the needs of customers which obtained via

quantitative and qualitative approaches. With the list in which customer needs are summarized,

numerous concepts with distinct characteristics are developed until the ideal and best concept is

selected through the processes of concept screening and scoring. Once the ideal concept is

finalized, the phase of robust design is introduced so that the efficiency of the product can be

maximized. Besides, in order to ensure the employment of the product is free from the risk of

harm, a detail engineering synthesis and analysis of the product will be conducted so that the

probability of the occurrence of mechanical failures can be diminished and minimized.

Apart from the detailed engineering analysis that performed manually, a computer-aided

design (CAD) is conducted to visualize the assembly of each of the components that composed

the finalized product. Moreover, finite element analysis (FEA) is also performed on the

analytical prototype due to cost effective and lead time in design can be significantly reduced. As

mentioned above, since the principal goal of the design and development of 3S Parking System

is to acts as an aid for household users who are confronted with problems of insufficient parking

spaces to park their extra cars, therefore, the design of the product must possesses the ability to

support cars with various weight and dimensions. Thus, the model of the car selected in the

design and analysis of the product is Lexus LX 570 due to its gigantic dimensions and heavy

weight which can be considered as the worst case scenario. Hence, the end product will be the

one that in which objectives are attained and successfully traverse through each phase in the

design processes.

Identifying Opportunities Page 2 of 78

2.0 Identifying Opportunities

Pahl et al (2007, p. 71) addressed that it has the possibility for the existence of gaps in

current product range between new product that are going to be introduced into current market

and existing product. Therefore, in order for new product to be successfully launched into

current market, strategic opportunities should be identified. The strategic opportunities can be

identified via the employment of the user scenarios method which is an alternative that furnish

beneficial starting and focal point to the design process by utilizing the standpoint of a user. This

is to ensure that the demand of users can be satisfied.

2.1 User Persona

Mr. X is a mechanical engineer, who owns a semi-detach house and lives in a big family.

Two of his family members might own new cars and they are confronted with problems of

insufficient parking within the house compound as more spaces are required for other

applications such as renovations or extensions of existing house. In addition, the vacant spaces

omitted can be employed to park more cars as well.

2.2 User Scenario

Mr. X requires a device that can assists him to economize space so that more cars can be

parked inside his house which has limited and confined parking spaces. Apart from that, the

device also has to be easy to operate or user friendly and suitable for cars with various weights

and dimensions.

2.3 Product Opportunity Proposal (Mission Statement)

Product opportunity proposal or sometimes referred as the mission statement is a

declaration in which the product vision and description, key business goals, markets targeted,

critical constraints and assumptions, criteria, as well as the stakeholders involved are

documented. The mission statement of the conceptual or idealized 3S Parking System are

manifested in Table 1 below.

Table 1: Product Opportunity Proposal (Mission Statement) for 3S Parking System

Product Opportunity Proposal (Mission Statement):

Smart, Safe & Sustainable (3S) Parking System

Product

Description

• A novel and innovative parking system that composed of a platform

which can be heightened and lowered by the employment of scissor-

lift device which are powered by hydraulic cylinders at both sides of

the platform.

• The main features of 3S Parking System is that two cars can be parked

together in a pile up manner by only occupying area of one parking

slot.

• Once a car is parked onto the platform, the hydraulic cylinders will

exert an axial compressive force to pull the scissor-lift to lift the

platform until a desired height in which second car can be parked

under the platform.

Identifying Opportunities Page 3 of 78

Product Opportunity Proposal (Mission Statement):

Smart, Safe & Sustainable (3S) Parking System (Continued)

Key Business

Goals

• Act as an aid for peoples who are confronted with problems of

parking their cars in normal residential housing area that has confined

parking spaces.

• Optimization of parking solution.

• Cut down the cost of constructing new parking slot.

• The 3S Parking System is expected to be market by the beginning of

January 2013.

• The targeted sales volume is expected to be approximately 2000 units

sold in a period of 3 years from the date in which the 3S Parking

System is launched to the market in Malaysia.

• The product is expected to be peddled into international market after a

period of 5 years from the launching date.

• The reckoned in sales revenue is approximately RM 18,000.00 with a

profit gain of RM 2,000 within a period of 3 years.

• The 3S Parking System is forecasted to dominate 30% of housing

development industry market share.

Primary Market • Moderate families who own weighty cars with large dimensions, and

lives in normal residential housing area that has confined parking

spaces.

Secondary

Market • Residents who lives in the residential area of which the houses are at

least semi-detached.

Assumptions and

Constraints

• Affordable by most of the moderate families.

• The product designed is capable to lift and support cars of various

weights and dimensions.

• The lifting device will not lower when there is a car parked below the

platform.

• Safe

Criteria

• User friendly

• Appear robust and safe

• Attractive to consumers

Stakeholders

• Distributors and resellers

• Customers

• Manufacturers

Clarifying Objectives Page 4 of 78

3.0 Clarifying Objectives

Objectives and aims clarification is a crucial procedure in the design of a new product as

it is beneficial in the domination as well as management of the design process. A list of

objectives of the product design can be generated based on the problem and mission statements.

The objectives listed based on the problem statement can be further categorized into higher-level

and lower-level objectives in which the importance of objectives is indicated.

As stated in preceding section, the primary problem statement is consumers who lives in

normal residential housing area with confined parking spaces are confronted with problems of

insufficient parking slots to park their extra cars. Therefore, a list of objectives is created and the

objectives generated are further categorized into higher-level and lower-level objectives based on

their significance as follows:

Higher-level Objectives:

• To design a Smart, Safe, and Sustainable (3S) Parking System that acts as a solution to the

problem statement as stated above through optimization – utilized the confined and limited

parking spaces in normal residential housing area to park maximum number of cars.

• To substitute the conventional parking methodology which practiced by most of the

consumers who dwell in normal residential housing area by a more effective and efficient

parking alternative.

Lower-level Objectives:

• The parking system is portable as it is composed by simple components which are easy to

assemble and disassemble.

• The utilization lifting device (scissor-lift device) in the parking system will cut down the cost

of constructing a new parking slot for houses to accommodate more cars.

• The scissor-lift device and the platform employed in the 3S Parking System are capable to lift

and support cars with various weights and dimensions.

• The lifting of platform in the parking system is powered by the employment of hydraulic

cylinders which is a practice of sustainability. This is due to the utilization of hydraulic

cylinders did not rely on power generated from resources which might result in the

contamination of environment such as charcoal fuel and diesel.

• Proximity sensor is employed to increase the parking accuracy so that the safety of consumers

is ensured.

• Fool proof system is introduced in the parking system for car detection. This is to ensure that

the “Down” switch will malfunction when objects are detected under the platform.

• Diamond plates with hump are installed on the platform to increase the car stability.

Based on the higher-level and lower-level objectives as listed above, an objective tree

which acts as an illustration of the significance of objectives which might ease the functional

analysis which going to be performed in the subsequent sub-section is depicted in Figure 1 below

Clarifying Objectives Page 5 of 78

Figure 1: Objective Tree of 3S Parking System

3S

Park

ing S

yst

em

Smart

Lift and Support Cars with Various Weights & Dimensions

Cut Cost Cut down the cost of

constructing new parking bay

Portable

Composed by components which are easy to assemble and

disassemble

Scissor-lift Device

Optimize conventional parking alternative

Utilizing space

Safe

Proximity Sensor Increase parking

accuracy

Fool Proof System Car or object detection

(Under platform)

Diamond Plates with Hump

To increase stability of car

Sustainable Employment of

Hydraulic Cylinders Do not powered by coal

and diesel

Function Analysis Page 6 of 78

4.0 Function Analysis

The objectives tree constructed in the preceding section illustrates that the design

problems has the possibility of possessing details of distinct levels. Due to different level of

details provided which might result in complication in the design processes such as investigation

of human factors and kinematics analyses of mechanisms included, an alternative called function

analysis in which indispensable functions of the product are taken into account is employed.

Apart from that, the problems associated with the corresponding essential functions can be

addressed as well.

The overall functions of the product can be categorized into various essential sub-

functions. The essential sub-functions with their corresponding means of achieving them are

listed in Table 2 below.

Table 2: Essential Sub-functions with Their Corresponding Means to Achieve Them

Essential Sub-

functions Means of Achieving Them

Parking accuracy and

stability

• Proximity sensor is utilized to increase the parking accuracy

• Hump is added onto the surface of the platform to ensure stability

Lifting of platform • The scissor-lift mechanism or the lifting device is powered by

hydraulic cylinders

Desired height • The platform is lifted to the desired height by scissor-lift

mechanism

Fool proof system • Use sensor to detect whether there is any object or car being

placed under the platform, so that the “Down” switch will

malfunction when objects are detected

Parking of next car • When the platform is lifted to the desired height and position,

next car can be parked below

Based on the essential sub-functions and their corresponding alternatives to accomplish it

as listed in Table 2 above, the interactions between sub-functions are illustrated in the block

diagram depicted in Figure 2 below.

Function Analysis Page 7 of 78

Figure 2: Block Diagram of 3S Parking System

Customer Needs List Page 8 of 78

5.0 Customer Needs List

The primary objective of listing out the customer requirements is significant as it will

assists in the design of product based on their perceptions. In order to come up with a list of

customer demands, an online survey in which information and perception of customers can be

obtained is carried out. The customer feedbacks obtained from the online survey is critical so

that a product in which customer needs and demands can be met is produced.

There are 20 copies of questionnaires were distributed and the information as well as the

customer perceptions are gathered and summarized in the Appendix. The information and

answers obtained from the online survey such as customer statement is further interpreted into

smaller goals of which the 3S Parking System need to attained are tabulated in Table 3 below.

Table 3: The Interpretation of Customer's Statement Obtained from Online Survey

No. Customer Statement Interpreted Needs

1.

The assembly and disassembly

processes of the parking system must

be easy.

The parking system can be constructed by

assemble all the variable parts.

2. The car park system must be stable all

the time.

The car park system will be tested whether it is

stable or not before go into market.

3. The appearance of the car park system

needs to be attractive.

The parking system composed of simple and

classic materials which are perfectly furnished.

4. The car park system needs to be

portable.

The parts of car park system can be assemble

and disassemble.

5. The dimensions of the parking system

must not be space consuming.

The car park system is compact and has a

reasonable size.

6. The car park system must be energy

efficient.

The parking system can be operated

automatically and manually.

7.

The car park system must be green

concept.

The car park system runs with hydraulic

cylinder which does not rely on the use of

lubricants. Besides, it is also not fuel power

product such as diesel power but electric

power.

8. The car park system must be

sustainable.

The car park system will be using eco-friendly

material.

9. The parking system must be safe.

The design of the parking system is based on

theoretical calculations and simulation which

ensure safe applications.

The customer demands and needs interpreted above are evaluated according to their

corresponding hierarchy. The importance of each customer needs and demands are rated from 1

to 9, in which “1” represent the need which is most important and “9” being the need which is

least important. The rating of each needs associated with their significances will narrow down

the focal point of the team in which strengthen of parts are required.

Customer Needs List Page 9 of 78

Table 4: Need Statement with Their Corresponding Importance and Hierarchy

No. Need Statement Importance Hierarchy

1. The car park system is compact and has a reasonable size. 5 Secondary

need

2. The car park system will apply simple and classic finish

to make an attractive image. 9

Tertiary

need

3. The car park system is combination between all variable

parts. 4

Primary

need

4. The parts of car park system can be assemble and

disassembly. 3

Primary

need

5. The car park system can run with automatically and

manually. 8

Tertiary

need

6. The car park system runs with hydraulic cylinder. 6 Secondary

need

7. The car park system will be using perfect materials. 7 Secondary

need

8. The car park system will be in safety mode. 1 Primary

need

9. The car park system will be test whether it is stable or not

before go into market. 2

Primary

need

Based on the summary of need statement as tabulated in Table 4 above, safety and human

factors considered in the 3S Parking System is the most importance need among the others. This

might due to the fact that safety and the capability of the scissor-lift device to withstand the

maximum loading are the primary concern for most of the customers.

Through the employment and identification of customer needs by rating them with their

relative significances, a deeper comprehending on the demand of customer can be obtained.

Through rating of customer needs in accordance with their hierarchy, the efficiency as well as

effectiveness of the team can be enhanced.

Performance Specifications Page 10 of 78

6.0 Performance Specifications

The specification of the product can be obtained by converting the customer demands and

needs interpreted above into terms which are technically in nature. The intention of product

specification is to provide a detail description of the product. The specifications of 3S Parking

System are tabulated in Table 3 below. The product specifications listed form the guideline in

the design and prototyping the product.

Table 5: Targeted Product Specifications of 3S Parking System

1. Performance Safe working load: 1600 kg

Allowable loading: 3000 kg

2. Mass (will be define after the detail design is done)

3. Size

Width: 2800 mm

Length: 3100 mm

Height: 2200 mm

4. Maintenance

Oiling: 2 months

Cycles: 6 months

Services of parts: 6 months

5. Ergonomics The product will automatically run when the button at the control box

is pressed.

6. Environment Can be used in both indoor and outdoor

7. Manufacturing

facility Manufactured by experienced technician

8. Material Structure (Alloy Steel)

9. Safety measures

• A sensor will tell user when to stop their car on top of the

platform.

• A sensor will tell the user whether there is presence of another

car below the platform so that the system will stop the hydraulic

from lowering the car further (if there is another car below the

platform).

• Ramps are introduced on the surface of the platform to prevent

the car from slipping.

• LED lights will be installed at the side of the platform to ensure

that the user can still park their car at the provided space

accurately in dark or low light condition.

10. Product life span Maximum 5 Years

11. Quality and

reliability

• A one and a half year warranty will be given to the user from the

date this product is purchased.

• The product will undergo a series of test before it is introduce to

the market.

12. Aesthetics Attractive finish

No defects

13. Cost Selling price: RM 7,000 to RM 9,000

Manufacturing setup price: ≤ RM 6,000

Determining Characteristics Page 11 of 78

7.0 Determining Characteristics

The assurance of quality of a product is a significant parameter in the design process as it

is a determinant that influences the economical successfulness of a manufacturing company. As

mentioned by Zakuan et al (2007, p. 105) and Pahl et al (2007, p. 517), quality of a new product

is vital other than just attain the technical function required. This is due to the fact that the

demand for quality is a critical factor for a company to subsist in a competitive market. Thus, in

order to optimize the market of the product, the quality of the product has to be assured by

assessing the characteristics associated with it.

Both the product attributes and engineering characteristics of the product must be taken

into considerations for the sake of optimization of the market. This can be done by introducing a

methodology for quality planning and quality assurance which is so-called the quality function

deployment (QFD). QFD is employed in the design process on account of the house of quality

which provides a clear visualization of relationship between the product attributes and

engineering characteristics that are often the main interest of marketers and engineers

respectively. This is a crucial phase in the design of product which must be conducted in order to

meet and satisfy both the product attributes and engineering characteristics. The relations of the

product attribute and engineering characteristics associated with the product are illustrated in the

house of quality depicted in Figure 3 below.

Based on the house of quality which acts as a visualization of the relationship between

product attributes and engineering characteristics as illustrated in Figure 3 below, system

furnishing is the engineering characteristic which is the least importance as compared to others.

On the contrary, the overall dimensions of the system and the maximum loading can the platform

sustains seems to be both the engineering characteristics and product attributes that have higher

level of importance. Therefore, more attention will be given on both the product attributes and

engineering characteristics which have higher importance.

Determining Characteristics Page 12 of 78

Figure 3: House of Quality for 3S Parking System

Generating Alternatives (Concept Generation) Page 13 of 78

8.0 Concept Generation (Generation of Alternatives)

Generating alternatives or sometimes referred as concept generation is one of the

significant phases in design process where the concepts of the product that addresses the demand

and requirements of consumers could be extensively explored. Besides, this is the phase in which

possible alternatives or solutions that will satisfy the needs of customers are listed prior to the

selection of various conceptual design. Before various alternatives have been generated, it is vital

to clarify the obstacles confronted by the project team which is the functional flow of the product

as illustrated in Figure 4 below.

Figure 4: Functional Diagram of 3S Parking System

Apart from secondary resources which are one of the methodologies employed to search

for related alternatives, the concepts of the product are also developed based on the house of

quality that relates the customer attributes and engineering characteristics which depicted in

Figure 3 in the preceding section where the characteristics of the product are determined. This is

due to the fact that competitive advantages could be added in the product. Thus, based on the

needs of customer listed in Section 5.0 and the house of quality, five concepts has been

generated and developed which will be discussed in the following sub-sections. The pros and

cons associated with the five concepts will be further analyzed and investigated. The best or

ideal conceptual design will be selected through the concept screening and scoring processes

which will be discussed in Section 9.0 which is the evaluation of alternatives.

8.1 Concept A

The intention of this design is to ensure the full utilization of vacant spaces within

a housing compound that has confined and limited parking spaces.

8.1.1 Operations

Once the “Rise” button on the control switch is pressed, all the four pillars

will rise from the ground by the force generated by the motor and the chain drive

which had been pre-installed into the ground. The side view of the conceptual

design as shown in Figure 5 below illustrates how the system operates when it is

fully-lowered to the minimum height. A ramp is utilized so that car can moves

onto the platform. Gearing mechanisms such as rack and pinion will be installed

on the pillar and motor respectively. As the motor is initiated, the pinion will

drive the rack in the vertical direction which results in lifting of platform.

Whereby, the function of chain is for power transmission from the motor to the

other three pillars. This is to ensure that all the pillars will moves simultaneously

so that inconsistency can be avoid.


Figure 5: 3D Sketch of 3S Parking System (Concept A)

8.1.2 Weakness or Problems

Although vacant spaces in the housing compound can be fully utilized

through the employment of this concept, however, the design of this concept is

impractical since a hole must be drilled on the ground prior to the installation of

the system which might results in excessive cost. Apart from that, the

employment of this design also will leads to the difficulties of maintenance of the

system.

8.2 Concept B

Since the employment of previous concept will results in various problems in

terms of cost and maintenance, therefore, Concept B is designed to overcome the these

disadvantages.

8.2.1 Operations

Each side of the platform is supported by metal supports at which sliders

are installed together. The sliders are assembled at each side of the platform to

ensure the platform only moves in vertical direction (see Figure 6 below). The

lifting and lowering of platform is controlled by the hydraulic rams which

installed on each side of the sliders. Based on the side view of Concept B as

illustrated in Figure 6 below, the two posts at each side of the platform are

positioned more towards the right side of the system. This is designed in such a

way that to reduce the bending moment created by larger loading at the frontal

part of the car.


Figure 6: 3D Sketch of 3S Parking System (Concept B)


Even the design of Concept B is to provide stabilization through

minimizing the bending moment by positioning the posts at each side of the

platform, but based on the knowledge from engineering statics, the design of

Concept B still might leads to instability of structure since the entire platform is

only supported by two posts.

8.3 Concept C

The second conceptual design is further developed so that the drawbacks

associated with it can be overcome. The drawbacks of Concept B are overcome by

introducing four pillars at each side of the platform and the hydraulic rams used to

provide vertical movement also been neglected. Instead, scissor-lift mechanism is

employed as the lifting device.

8.3.1 Operations

Two-stage scissor-lift mechanism is introduced at each side of the

platform as the lifting device so that the maximum height which can be attained

by the previous two conceptual designs can be increased. Besides, hydraulic

cylinder is introduced to provide vertical motion of the lifting device. As shown

in Figure 7 below, one end of the hydraulic cylinder is fixed to the ground


whereas one end is connected to the scissor-lift mechanism. A track will be

installed on the ground to guide the roller of the scissor-lift mechanism.

Figure 7: 3D Sketch of 3S Parking System (Concept C)


Although stabilization of structure of the design can be guaranteed by

introducing pillars at each corner of the platform which is installed to the ground,

but difficulties in maintenance is created. It causes difficulties to the technicians

during parts replacement or checking of defects. Besides, another significant

problem that can be observed based on the 3D sketch of Concept C as illustrated

in Figure 7 above is caused by the position of hydraulic cylinder. If the hydraulic

cylinders are positioned at the middle position of the two-stage scissor-lift

mechanism, the hydraulic force required to lift the platform can be reduced by

half as compared to the installation at bottom. Thus, problem in terms of

mechanical efficiency is induced.

8.4 Concept D

Due to the difficulties in maintenance caused by the four pillars at each of the

corner of platform, Concept C is further developed by removing the four pillars and the

size of the platform is reduced by substituting two smaller platforms on the top of the

scissor-lift mechanism at each side of the parking system.


8.4.1 Operations

The hydraulic cylinders are installed at each side of the parking system at

is positioned parallel to the ground to increase the mechanical efficiency. As

mentioned above, the platform is designed in such a way that only wheels of car

are supported which illustrated in Figure 8 below.

Figure 8: 3D Sketch of 3S Parking System (Concept D)


Although the cost in design can be cut down by introducing platform of

smaller size and mechanical efficiency can be enhanced by re-position the

hydraulic cylinder, but one significant drawback can be resulted is that the car

parked at the bottom can be dirt by the wastage of the car parked above such as

the leakage of engine oil and so on. Besides, the employment of platform with

smaller size only restricted to cars with large dimensions which results in

performance degradation. Apart from that, as shown in Figure 8 above, longer

scissor-lift legs are required in order to lift the platform to the desired height since

the scissor-lift mechanism only encompasses of single stage.

8.5 Concept E

The problems caused by the smaller size platform and the longer scissor-lift legs

are overcome by utilizing back the platform in Concept D, and dual scissor-lift

mechanism is introduced.


8.5.1 Operations

Dual scissor-lift mechanism is employed in Concept E so that the

hydraulic force required to lift the platform can be reduced significantly. Besides,

the loadings exerted by the cars can be shared as well. The hydraulic cylinder is

positioned between the dual scissor-lift mechanisms so that more spaces can be

economized.

Figure 9: 3D Sketch of 3S Parking System (Concept E)


As manifested in Figure 9 above, the pathway for the roller or the track is

fixed on the ground. This will restrict the mobility of the parking system. Apart

from that, the position of the hydraulic cylinder is no longer can be placed

horizontally due to the pathway of the roller and hence results in the degradation

of mechanical efficiency.

8.6 Concept F

Due to the restriction of mobility, Concept E is further developed and enhanced. This is

done through the implementation of mechanism such as slot and pin.

8.6.1 Operations

The slot or sometimes referred as bottom roller track is employed to the replace

the fixed pathway for the roller. Besides, the base of the system is changed so that it is

movable (see Figure 10 below).


Figure 10: 3D Sketch of 3S Parking System (Concept F)


The slot or the roller track might experience wear resistance in a short

period of time. This is due to the huge loadings exerted by the body and platform

as well as the weight of car.

Evaluating Alternatives (Concept Selection) Page 20 of 78

9.0 Concept Selection (Evaluation of Alternatives)

Alternatives evaluation or sometime referred as concept selection is another significant

phase in design process as it is where the best and ideal concept is selected based on the needs of

customers as well as the engineering characteristics. Once various concepts had been developed,

the best concept will be selected by the application of weighted objectives method or it can be

termed as the concept scoring and testing as well. Weighted objectives method is employed in

the evaluation of alternatives as the strengths and weaknesses associated with each concept can

be analyzed and evaluated.

9.1 Concept Screening

Screening table is applied in the process of concept screening as different

characteristics of distinct conceptual designs can be listed and compared with a reference

concept. All the concepts developed in the preceding section are ranked according to the

selection criteria. Through the process of concept screening, one or two concepts will

either be eliminated or combined. The selection criteria are based on the demands or

needs of customer.

Table 6: Matrix of Concept Screening

Selection Criteria Concepts

Metric

No. Customer Attributes

A

(Reference) B C D E F

1 User friendly 0 + 0 + + +

2 Ability to support

various types of car 0 0 0 0 0 0

3 Dimension of parking

slot 0 + - - + +

4 Durability 0 - + + + +

5 Maintenance 0 0 + + + +

6 Safety 0 - + 0 0 0

7 Sustainability 0 + + + + +

8 Portability 0 + 0 + 0 +

9 Appearance 0 + 0 + 0 +

Sum +’s 0 5 4 6 5 7

Sum 0‘s 9 2 4 2 4 2

Sum –‘s 0 2 1 1 0 0

Net Score 0 3 3 5 5 7

Rank 3 4 4 4 4 5

Continue? No Combined Combined Develop

Based on the matrix of concept screening as shown in Table 6 above, the (+), (0)

and (-) signs are used to make comparisons between each of the concepts with the

reference concept. (+) and (-) will be allocated when the concept is better or worse than

the reference concept respectively. Whereas, (0) indicates that there has no deviations

between the specific concept and reference concept.


9.2 Concept Scoring (Weighted Objectives Method)

Based on the ranking of concepts as tabulated in the concept screening matrix above, further comparison are made by the

employment of the weighted objectives methodology. This is due to the fact that the pros and cons associated with each concept can be

clearly visualized and analyzed.

Table 7: Table of Concept Scoring (Weighted Objectives Method)

Selection Criteria Weight

(%)

Concepts

A B & C (Combined) D & E & F

(Combined)

Metric

No. Customer Attributes Rating

Weighted

Score Rating

Weighted

Score Rating

Weighted

Score

1 User friendly 10 3 0.30 4 0.40 4 0.40

2 Ability to support various types

of car 25 3 0.75 3 0.75 5 1.25

3 Dimension of parking slot 15 3 0.45 3 0.45 5 0.75

4 Durability 10 3 0.30 4 0.30 5 0.50

5 Maintenance 5 3 0.15 3 0.15 5 0.25

6 Safety 20 3 0.60 4 0.80 5 0.10

7 Sustainability 5 3 0.15 3 0.15 3 0.15

8 Portability 5 3 0.15 4 0.20 5 0.25

9 Appearance 5 3 0.15 2 0.10 5 0.25

Total Score 3.00 3.30 3.90

Rank 3 4 5

Continue? No No Develop

According to the results obtained from the rating of concepts by the weighted objectives method as tabulated in Table 7 above, a

combinations of concepts D, E and F are further developed in which the drawbacks caused by the initial concepts can be overcome. This can

be attained by implementing a dual two-stage scissor-lift mechanism at each side of the 3S Parking System in which it is portable. Besides,

the hydraulic cylinder will be positioned at the middle of the scissor-lift mechanism so that the mechanical efficiency can be enhanced. The

rating scales used to rate each of the concepts listed in Table 6 and 7 above are tabulated in Table 8 below.


Table 8: Rating Scale for Various Concepts Listed in Table 6 & 7

5-point Scale Meaning

1 Inadequate (More worse than reference concept)

2 Weak (Worse than reference concept)

3 Satisfactory (Similar as reference concept)

4 Good (Better than reference concept)

5 Excellent (Perfect or ideal concept)

9.3 Concept Testing

Once the best and ideal concept had been selected, another significant phase in

alternative evaluation which is so-called the concept testing is conducted. The primary

intention of concept testing is to investigate and analyze the customer demands and needs

of 3S Parking System in detail. This is done in order to meet the satisfaction of

customer’s requirements. Through concept testing, not only the market of the 3S Parking

System can be optimized, instead, the current conceptual design can be further improved

and the performance of the product can be enhanced based on the results and information

obtained from the concept testing as well.

Online survey is conduct by the project team to generate a survey for the product

in a selected group. The group stands out of 20 people which consist of household users

that are randomly choose among friend’s parents and neighbors. For convenient and

flexible purposes, the link towards the online survey is given to them for answering at

their own free times without affecting their daily routine. The questionnaires are designed

to be understandable and simple with contains acquired for the concept testing. Selections

of opinion are given to target groups to click in the online survey together with some

commendations part provided. A brief introduction of the product is given together with

the online survey to allow and ensure the target group understand and had an insight

regarding the product before answering it. This will results in better data and constructive

comments obtain once they had a rough idea about what it is about and the purposes.

Through this process, the team will be able to gain more knowledge for further

improvement on the product.

According to the data obtained from the online survey(appendix) it shows that 5

out of 20 people is satisfied with the current parking system whereas 75% of the 20

people are not satisfied with it and opt for an alternative parking system. 95% of the

people thinks that the product if feasible and useful for them. The 5% that think that it is

not useful for them may due to the cause that the family size is smaller and number of

cars is not many. However, most of them will consider the aspects of durability, price

and quality of the product when purchasing it. This is known first hand as the price of a

product will be the main consideration for consumer in process of purchasing of any

products or services. Thus for better quality product the price will be higher and therefore

the price of the product will be at average range. In conclusion, the concept testing from

the online survey prove the team had been on the right track as the needs and wants of the

customer is basically similar with the results obtained from this testing. In conjunction

with this, the team will look into the product for further improvement and enhancement

to assure a better durability and quality achieved.

Product Architecture Page 23 of 78

10.0 Product Architecture

Product architecture is basically the arrangement of functional elements that allocated to

the physical components which become the building blocks for the product. The functional

elements of product architecture are the individual operations of the product whereas the

physical components are the parts and components or subassemblies that implement the product

functions.

Architecture can be both integral and modular whereby interactions between chunks are

well defined for modular than integral. Modular design had better indication of physical

components which each physical component or chunks implements one or few functional

elements in the product.

For generating the product architecture of a product, few steps and procedures are

required which are the creation of schematic of product, and cluster the elements to schematics

to obtain the product variety desired.

10.1 Schematic of 3S Parking System

Figure 11: Schematic of 3S Parking System


10.2 Schematic of Clustered Elements

Figure 12: Schematic of Clustered Elements


10.3 Geometric Layout

Figure 13: Geometric Layout of 3S Parking System

Detail Design (Engineering Synthesis and Analysis) Page 26 of 78

11.0 Detail Design (Engineering Synthesis and Analysis)

It is ordinary that a designer is deficient in technical knowledge in the identification of

faults associated with the product which might results in failures of the system. Therefore, it is a

crucial move to assess the disturbing factors or sometimes referred to possible failures associated

in the design process. In order to determine the possible failure modes and estimate the risks

associated with each mode, failure modes and effect analysis (FMEA) has been employed.

11.1 Failure Modes and Effect Analysis (FMEA)

According to Pahl et al (2007, p. 529), failure modes and effect analysis (FMEA)

is a methodology to identify and examine the possible failures and their corresponding

effect associated with the product analytically. This methodology has been extensively

employed in manufacturing industries as potential failure of the product and

corresponding effect can be identified and estimated which benefits the design process by

minimize the cost as well as lead time in design.

Failure modes can be interpreted as the defects in the product, design process that

affect the consumers. Effect assessment is the estimation of probable outcome or risk

associated to the corresponding failure. The possible failure modes of 3S Parking System

are identified and illustrated in Figure 14 below. Apart from that, appropriate operations

to reduce the probability the failures are listed in Table 9 below as well.

The ratings of the possible failures are according to the Risk Priority Number

(RPN) which can be computed by the following equation:

RPN = S × O × D

where

S = Severity (Effect of failure)

O = Occurrence (The probability of failure or the frequency of the occurrence)

D = Ability to detect problems and failures

The rating scale of severity (S), occurrence (O) and detection (D) is ranged from 1 to 10

in which indicate low to high.

Scope of Analysis

Components system level has been employed in the FMEA.


Figure 14: Block Diagram of 3S Parking System


Based on the block diagram as illustrated in Figure 4 above, the failure modes and effect analysis (FMEA) for 3S Parking System are listed in tables

below.

Table 9: Failure Modes and Effect Analysis (FMEA) of Body for 3S Parking System

Item and Functions Failure

Mode Effect of Failure Cause of Failure Controls S O D RPN

Two-stage Scissor-lift (Lifting

Device)

• Structural support

• Provides vertical movement

(Lifting)

Deflection

• Unable to reach

the desired

height

• Buckling of

scissor-lift legs

• Structural

deformation

• Huge loading

exerted by the cars

• The bending stress

is greater than the

yield strength of the

material

Material with higher yield

strength should be used 8 2 7 112

Top Roller

The horizontal movement of the

roller will results in the vertical

movement of lifting device

Wear

• Derail of roller

• Sound pollution

Friction

Lubricants should be added

periodically to the surface

of the roller and the track

3 4 4 48

Platform

Base to support loading exerted

by cars

Bending and

Deflection

• Structural

deformation

• Instability of the

3S Parking

System

• Huge loading

exerted by the cars

• Yield strength of the

material

Material with higher yield

strength should be used 8 2 7 112


Table 10: Failure Modes and Effect Analysis (FMEA) for Force Generator of 3S Parking System


Mode Effect of Failure Cause of Failure Controls S O D RPN

Hydraulic Cylinder

• Converts internal

pressure to hydraulic

force

• The hydraulic force

provides vertical

Deflection Malfunction of the

hydraulic cylinder

Cyclic fatigue induced by the

extension and retraction

operations

Hydraulic cylinder with

better quality is employed 7 2 2 28

Table 11: Failure Modes and Effect Analysis (FMEA) for Base of 3S Parking System


Mode Effect of Failure

Cause of

Failure Controls S O D RPN

Bottom Roller

Provides vertical

movement of the lifting

device

Wear

• Derail of roller

• Sound pollution

Friction Lubricants should be added periodically to

the surface of the roller and the track 3 4 4 48

Bottom Roller Track

• Vertical movement of

load

• Base for body of 3S

Parking System

Deflection

• Performance

degradation

• Sound pollution

• Permanent

deformation

• Huge

loading

• Friction

• Lubricants should be added

periodically to the surface of the roller

and the track

• Material with higher yield strength

should be used

3 4 5 60


Table 12: Failure Modes and Effect Analysis (FMEA) for Control System of 3S Parking System

Item and Functions Failure Mode Effect of Failure Cause of Failure Controls S O D RPN

Electricity

Supply electrical power to

the hydraulic cylinder

Power cut

Unable to perform

the lifting

operation • No power supply

Battery is used as a power

source during power cut 6 2 2 24

Control Switch

Used to switch on the

electricity to power the

hydraulic cylinder

Malfunction of

switch

The switch is fail

to operate Improper handling

A better switch that has longer

product life cycle should used 3 4 1 12

Control Circuit

Used to control the entire

mechanism

Fail to function

automatically

The control circuit

is fail to operate

Defect in circuit

components

A programmable control

circuit should be introduced 6 3 2 36


11.2 Detail Calculations

For the sake of safety utilization of the product that is free from the risk of harm,

a detailed engineering analysis had been performed by the team in the design of the 3S

Parking System. According to the risk priority number (RPN) from the Failure Modes

and Effect Analysis carried out by the team in Section 11.1, the team had found that there

are several portions in which more attentive analysis should be taken into account and

considerations. Among the sections are the minimum cross-sectional areas required for

the legs of the lifting mechanism in order to sustain the loading of the car; the minimum

thickness of the platform needed so that the bending moment as well as bending stress

can be minimized. Apart from that, the selection of the materials used and the hydraulic

cylinder are the primary concern as well.

In order to ease the process of calculations, several equitable and logical

assumptions had been made by the team. The assumptions are listed as follows:

• The distribution of loading exerted by the weight of the car onto the surface of the

platform is point load. Since the proposed car used in the design of the 3S Parking

System is Lexus LX which encompasses of four wheels, therefore, four point loads is

considered in this case.

• The distribution of point loads on the surface of the platform are equal in magnitude

and are equally spaced according to the Wheel Base Distance (dW = 2.85 m for Lexus

LX).

• The platform employed in the 3S Parking System is modeled as a beam. Since the all

the four edges of the platform are simply supported (two pin supports and two roller

supports), thus occurrence of maximum bending moment is about the x-axis which is

the worst case scenario.

• Since one of the ends of the scissor-lift is set to be free to move along the track,

therefore, the support can be modeled as roller support. Whereas, the other support is

modeled as pin support.

• There will be two horizontal forces that are equal in magnitude exerted by the two

single-rod hydraulic cylinder acting on Joint C and D (see Figure 15 below).

11.3 Load Analysis

In order to select an single-rod hydraulic cylinder for the 3S Parking system, the

magnitude of hydraulic force required to lift the proposed car – Lexus LX that has an

approximated weight of 30,000 N should be known, the load analysis in which the lifting

mechanism is fully-lifted are performed as follows. Due to the fact that, all the lifting

mechanisms are identical to each other, thus, only one side of the lifting mechanism is

considered and analyzed.


Since each side of the 3S Parking System consists of two scissor-lift

mechanisms, therefore, the weight of the car is divided by 4, and each of the point

loads has a magnitude of W/8 as shown in the free body diagram of the scissor-lift

mechanism during the fully-lifted position as depicted in Figure 15 below.

Figure 15: Free Body Diagram (F. B. D.) of the Scissor-lift Mechanism

during the Fully-lifted Position

The length of the leg AD, BC, CF, and DE are L = 2.9 m.


As shown in Figure 1 above, point A and B are actually the pin and roller

support respectively. The support reactions at A and B are determined based on

the free body diagram of the platform as illustrated in Figure 16 below.

Figure 16: Free Body Diagram (F. B. D.) of the Platform

Taking the summation of moment about point A and assuming counter-clockwise

moment is positive gives:

( )

( )

( ) ( )

8

08

02828

0veCCW

WB

daBdaW

daBddaWddaW

M

y

y

y

WW

A

=

=−+−−

=−+

+−−

−−−

=+ ∑

With By known, summing the forces in vertical direction yields:

( )8

088

; 0veW

ABWW

AF yyyy =⇒=+−−=↑+ ∑

To find Ax, taking the summation of forces in horizontal direction results in

Ax = 0.

The magnitude of Ay and By can be determined by substituting W = 30,000 N into

both the expression for Ay and By above:

N 3,750== yy BA


Analysis for Leg 1

Figure 17: Free Body Diagram (F. B. D.) for Leg 1

Based on Figure 17 above, by taking the summation of moment at the joint J1

equal to zero and assuming counter-clockwise is positive gives:

( )

θ

θθ

cot8

0sin2

cos28

0veCCW 1

WF

LF

LW

M

CD

CD

J

=

=

−

=+ ∑

Substituting W = 30,000 N into the equation above yields:

N 3,750cotθ=CDF

where the angle θ ranges from 1.7° to 20.9°. The lateral forces, FCD exerted by the

two single-rod hydraulic cylinders when the lifting-mechanism are fully-lifted and

lowered are:

At the lowest position, ( ) ( ) N 126350.7=°=°= N65.1cot75037.1 ,FCD θ

At the highest position, ( ) ( ) N 9820.3=°=°= N9.20cot75039.20 ,FCD θ

The forces acting on leg 2 are the lateral force exerted by the single-rod

hydraulic cylinder FCD, and the support reaction By. Since all the forces acting on

leg 2 are known, thus the analysis for leg 2 can be neglected.


Analysis for Leg 3

Figure 18: Free Body Diagram (F. B. D.) of Leg 3

According to the free body diagram for leg 3 as depicted in Figure 18 above,

taking the summation of moment about the joint J2 equal to zero and assuming

counter-clockwise moment is positive gives:

( )

θ

θθ

tan

0cos2

sin2

0veCCW 2

CDy

yCD

J

FF

LF

LF

M

=

=

+

−

=+ ∑

Based on previous calculations, it has found that θcot8

WFCD = , therefore,

8

tancot8

tanWW

FF CDy =⋅== θθθ

Substituting W = 30,000 N into above equation gives:

N 3,750=yF

Likewise, the support reaction of pin support E also can be computed in similar

manner as follows.


Analysis for Leg 4


Based on the free body diagram for leg 4 as shown in Figure 19 above, the

support reaction exerted by pin support E can be determined by taking the

summation of moment about J2 equal to zero and assuming counter-clockwise

moment is positive.

( )

θ

θθ

tan

0sin2

cos2

0veCCW 2

CDy

CDy

J

FE

LF

LE

M

=

=

+

−

=+ ∑

Similarly,

8

tancot8

tanWW

FE CDy =⋅== θθθ

Substituting W = 30,000 N into the above equation yields:

N 3,750=yE

Based on the calculations above, it can be clearly seen that the magnitude

of the lateral forces exerted by the two single-rod hydraulic cylinder is strongly

depends on the angle with respect to the horizontal. The variation in hydraulic

force due to the deviations in angle with respect to horizontal is illustrated in

Figure 20 below. According to the plot of hydraulic force versus the angle

measured from the horizontal as shown in Figure 20, the hydraulic force varies

inversely with the angle.


Figure 20: Plot of Hydraulic Force, FCD (N) versus Angle, θ (Deg.) with Respect to the Horizontal

11.4 Selection of Hydraulic Cylinder

According to the plot of hydraulic force versus the angle measured with respect to

horizontal as depicted in Figure 6 above, it can be clearly seen that a larger hydraulic

force is required when the lifting device is at its lowest position which has an angle of

θmin = 1.7°. Based on the magnitude of hydraulic force obtained from the calculations

above, Rexroth MP5 Single-rod Hydraulic cylinder with self-aligning rear clevis

mounting (see Figure 21 & 22 below) can be employed in the design of 3S Parking

System. This is due to the fact that the maximum length of the two extended hydraulic

cylinders obtained from the catalogue is greater than the maximum length extended by

the scissor-lift mechanism. The information of the hydraulic cylinder is shown in Figure

23 as illustrated in subsequent page.

9000

29000

49000

69000

89000

109000

129000

0 2 4 6 8 10 12 14 16 18 20 22

Hydra

uli

c F

orc

e, F

CD (

N)

Angle, θ (Deg.)

Hydraulic Force, FCD (N) vs. Angle, θ (Deg.)


Figure 21: Selected Hydraulic Cylinder (Bosch Rexroth AG, 2003, p. 4)

Figure 22: Mounting Styles MP5 (Boshc Rexroth AG, 2003, p. 10)


Figure 23: Selection of Hydraulic Cylinder (Bosch Rexroth AG, 2003, p. 5)


11.4.1 Hydraulic Cylinder Calculations

Since two single-rod hydraulic cylinders are employed in each side of the

platform, therefore, the maximum force hydraulic force is divided by two. Based

on the information obtained from the catalogue, the properties of hydraulic

cylinders are determined as follows.

Maximum Force:

N 63175.35==2

N 7.126350Force Maximum

Since 10% of the hydraulic force is utilized to overcome the friction in hydraulic

seal, therefore, the efficiency of the hydraulic cylinder is η = 90%.

Actual Cylinder Force Required:

N 70194.83=

=

=

9.0

N 3175.356

N 3175.356Required ForceCylinder Actual

η

Diameter of Hydraulic Cylinder:

m 0.0747=××

=

×=×

×=

Pa 10160

N) 70194.83(4

Pa) 10160 (Pressure Pressure

Force Actual4DiameterCylinder

5

5

π

π

Length of Attachment, k:

mm 1106=

+=

+=

mm 185 mm 261

XOCHk

Stroke (Catalogue), s = 660 mm

Retracted Cylinder Length (Catalogue):

mm 1106=

+=

+=

mm 660mm 446

LengthCylinder Retracted sk


Extended Cylinder Length (Catalogue):

( )mm 1766=

+=

+=

mm 6602mm 446

2LengthCylinder Extended sk

Maximum Extended Scissor-lift Length = 3089.88 mm

Extended Cylinder Length of Two Hydraulic Cylinders = 3532 mm

Information from the catalogue used in the calculations above is shown in Figure

24 to 28 below.

Figure 24: Schematic of Area, Force and Flows in the Hydraulic Cylinders (Bosch Rexroth AG, 2003, p. 6)


Figure 25: Weight of Selected Cylinder (Bosch Rexroth AG, 2003, p. 7)

Figure 26: KK Values (KK = M48x2) (Bosch Rexroth, 2003, p. 11)


Figure 27: CH Value of M48x2 (Bosch Rexorth, 2003, p. 28)

Figure 28: Value of Maximum Stroke (Bosch Rexorth, 2003, p. 3)


11.4.2 Buckling of Piston Rod

According to Bosch Rexroth (2003, p. 30), a hydraulic cylinder that is

subjected to large internal pressure may result in the buckling of piston rod.

Therefore, the buckling of the piston rod employed in the hydraulic cylinder is

taken into considerations. There are several reasons that will contribute to the

bucking of piston rod which might leads to mechanical failure of the system.

Among the reasons are:

• The large stroke of the hydraulic cylinder

• Small piston rod diameter

• High loading

The lifting device or the scissor-lift mechanism will fail if the piston rods

utilized in the hydraulic cylinders are likely to buckle. Hence, the possibilities of

buckling can be checked by the calculations below. The equation employed in the

checking of piston-rod buckling is as follows:

L = S × K

where L = Theoretical stroke (Value obtained from table)

S = Stroke

K = Load guidance factor (K = 2 for MP5 Mounting Type Cylinder)

L = S × K = (3089.88 mm – 2919 mm) × 2 = 341.76 mm

Figure 29: Load Guidance Factor, K (Bosch Rexroth, 2003, p. 31)

Based on the calculations above, the calculated L is 341.76 mm which is

relatively smaller than the maximum stroke which is 859 mm at pressure of 160

Bar. Therefore, it can be concluded that the piston rod in the selected hydraulic

cylinder is safe from buckling.


Figure 30: Maximum Stroke (Catalogue) (Bosch Rexroth, 2003, p. 30)


11.5 Selection of Material

Due to the high loading exerted from the cars onto the platform as well as the

lifting mechanism employed in the 3S Parking System, the material utilized in each

component of the product must possesses of mechanical properties such as high strength

and toughness. Through several researches, ASTM-A709 Grade 690 Alloy Steel has been

selected as the material employed in each of the component of the 3S Parking System.

The selection of ASTM-A709 Grade 690 Alloy Steel as the material employed in

each of the component of the product is due to the fact that it is categorized as high-

strength, low alloy (HSLA) steels. Most of the alloy steels being categorized in this group

have alloying concentration up to 10-wt% and majority of the alloying elements

contented in HSLA Steels are Nickel (Ni), Chromium (Cr), Molybdenum (Mo) which are

extensively employed in many of the engineering applications in which structural

strength is critical as mentioned by Callister (2006, p. 362).

According to the Tables of Typical Properties of Selected Materials Used in

Engineering in Beer (2012, p. 230) (see Appendix 3), the Modulus of Elasticity (or the

Young’s Modulus) as well as the yield strength of ASTM-A709 Grade 690 Alloy Steel is

E = 200 GPa and σY = 690 MPa respectively.

11.6 Bending Moment and Deflection (Platform)

As mentioned earlier in Section 11.2, one of the significant portion in which detail

analyses and considerations should be taken in account is the minimum thickness of the

platform required in order to sustain the large loadings exerted by the car. In order for the

minimum thickness of the platform to be determinate, the location where the maximum

deflection of the plate occurred should be known. This is due to the fact that at that

particular location, the probabilities of the occurrence of largest bending moment is the

highest.

According to Beer (2012, p. 230), the elastic flexural formula for pure bending

states that the allowable stress or sometimes referred as the bending stress varies directly

to the bending moment. The allowable bending stress also can be related with the yield

strength of the material as well as the safety factor assigned by the equation σall = σY/S.F.

which forms an alternative to determine the minimum thickness required. Therefore, in

order to determine the maximum deflection which will leads to the largest magnitude of

bending moment produced by the loadings applied on the platform, two extreme

conditions at which the lifting mechanism is fully-up and fully-lowered are taken into

considerations.

The calculations of the maximum bending moment and deflection of the platform

for both the conditions are based on the free body-diagram as illustrated in Figure 31

below, and a safety factor of 2 is assumed. This is because the material employed in the

system is well-known, the operation of system is under reasonably environmental

conditions, and the system is subjected to loading that can be calculated.


Figure 31: Free Body Diagram (F. B. D.) of the Platform

Bending Moment and Deflection of the Platform when the Lifting Mechanism is at the

Fully-lifted Position

The magnitudes of the nomenclatures in Figure 31 for the lifting mechanism at the fully-

lifted position are tabulated in Table 13 below:

Table 13: Magnitudes of Nomenclatures for the Lifting Mechanism at Fully-up Position

Nomenclatures Magnitude

Length of the platform, a 3.1 m

Displacement, d 0.181 m

Wheel base distance, dW 2.85 m

Weight of the car, W 30,000 N

Width of the platform, w 2.8 m

Figure 32: Free Body Diagram (F. B. D.) of the Platform when the Lifting Mechanism is at Fully-

lifted position


Based on the free body diagram of the platform when the lifting mechanism is at the

fully-lifted position as depicted in Figure 32 above, the moment function can be

expressed by singularity function as follows:

( ) mN 8845.237500345.03750375011

⋅−−−−= xxxxM

The equation of elastic curve is given by:

( )

mN 8845.237500345.03750375011

2

2

2

2

⋅−+−+−=

−=

xxxdx

ydEI

xMdx

ydEI

Integrating twice in x,

3

21

333

2

1

222

mN 8845.26250345.0625625

mN 8845.218750345.018751875

⋅++−+−+−=

⋅+−+−+−=

CxCxxxEIy

Cxxxdx

dyEI

Boundary Conditions:

[x = 0, y = 0]:

( ) ( ) 000006250 221

3 =⇒++++−= CCC

[x = 2.919 m, y = 0]:

( ) ( ) ( ) ( )

5910.186

919.20345.06258845.2625919.26250

1

1

333

=

+++−=

C

C

Hence,

3333

2222

mN 5910.1868845.26250345.0625625

mN 5910.1868845.218750345.018751875

⋅+−+−+−=

⋅+−+−+−=

xxxxEIy

xxxdx

dyEI

If the maximum deflection, ymax happens between 0 ≤ x ≤ 0.0345 m, then,

m 3155.005910.18618750 2 =⇒=+−⇒= xxdx

dy

At x = 0.3155 m,

( ) ( )m 1089.531

3155.0maxEI

xyy ===


If the maximum deflection, ymax happens between 0.0345 m ≤ x ≤ 2.8845 m, then,

( )

m 4595.1

08228.188375.129

05910.1860345.018751875

0

22

=

=+−

=+−+−

=

x

x

xx

dx

dy

At x = 1.4595 m,

( ) ( ) m 7676.1371

4595.1maxEI

xyy ===


( ) ( )

m 6035.2

03853.15789255.109461875

05910.1868845.218750345.018751875

0

2

222

=

=+−

=+−+−+−

=

x

xx

xxx

dx

dy

At x = 2.0635 m,

( ) ( )m 1087.531

6035.2maxEI

xyy ===

By comparing the maximum deflection at three distinct positions, the maximum

deflection which has the largest magnitude occurs at x = 1.4595 m. Thus, the maximum

bending moment is

( ) ( ) ( )[ ] mN 129.375 ⋅=⋅−=== mN425.137504595.137504595.1max xMM

The elastic flexural formula for pure bending is given by:

xxI

yM max

all =σ

where y and Ixx are the distance from the neutral axis and second-moment of area

respectively.

And, the allowable stress can be related with the yield strength and safety factor by the

equation

.S.F

allYσ

σ =


Equating both the equations above gives:

.S.F

max Y

xxI

yM σ=

Substituting 2

ty = and 3

12

1wtI xx = yields:

2) (S.F. 12 max ==

w

Mt

Yσ

As tabulated in Table 13 above, by substituting w = 2.8 m and σY = 690 MPa into the

above equation, the minimum thickness of the platform is

m) .82Pa)( 10690(

m)N 375.129(126

m 108.964−×=

×

⋅=t

Bending Moment and Deflection of the Platform when the Lifting Mechanism is at the

Fully-lowered Position

The magnitudes of the nomenclatures in Figure 7 for the lifting mechanism at the fully-

up position are tabulated in Table 14 below:

Table 14: Magnitudes of Nomenclatures for the Lifting Mechanism at Fully-lowered Position


Length of the platform, a 3.1 m

Displacement, d 0.01012 m

Wheel base distance, dW 2.85 m


Width of the platform, w 2.8 m

Figure 33: Free Body Diagram (F. B. D.) of the Platform when the Lifting Mechanism is at Fully-

lowered Position


Based on the free body diagram of the platform when the lifting mechanism is at the

fully-lowered position as shown in Figure 33 above, the moment function can be

expressed by singularity function as follows:

( ) mN 96994.2375011994.03750375011

⋅−−−−= xxxxM


( )

mN 96994.2375011994.03750375011

2

2

2

2

⋅−+−+−=

−=

xxxdx

ydEI

xMdx

ydEI


3

21

333

2

1

222

mN 96994.262511994.0625625

mN 96994.2187511994.018751875

⋅++−+−+−=

⋅+−+−+−=

CxCxxxEIy

Cxxxdx

dyEI


[x = 0, y = 0]:

( ) ( ) 000006250 221

3 =⇒++++−= CCC

[x = 3.08988 m, y = 0]:

( ) ( ) ( ) ( )

9024.667

08988.311994.062596994.262508988.36250

1

1

333

=

+++−=

C

C

Hence,

3333

2222

mN 9024.66796994.262511994.0625625

mN 9024.66796994.2187511994.018751875

⋅+−+−+−=

⋅+−+−+−=

xxxxEIy

xxxdx

dyEI

If the maximum deflection, ymax happens between 0 ≤ x ≤ 0.11994 m, then,

m 5968.009024.66718750 2 =⇒=+−⇒= xxdx

dy

At x = 0.5968 m,

( ) ( ) m 5421.3331

5968.0maxEI

xyy ===



( )m 5449.1

09024.66711994.018751875

0

22

=

=+−+−

=

x

xx

dx

dy

At x = 1.5449 m,

( ) ( ) m 6920.5351

5449.1maxEI

xyy ===


( ) ( ) m 4952.2

09024.66796994.2187511994.018751875

0

222

=

=+−+−+−

=

x

xxx

dx

dy

At x = 2.5942 m,

( ) ( )m 62.3321

5942.2maxEI

xyy ===

By comparing the maximum deflection at three distinct positions, the maximum

deflection which has the largest magnitude occurs at x = 1.54449 m. Thus, the maximum

bending moment is

( ) ( ) ( )[ ] mN 449.775 ⋅=⋅−=== mN42496.137505449.137505449.1max xMM

Likewise, the minimum thickness of the platform when the lifting mechanism is at the

fully-lowered position can be computed by the equation derived before:

2) (S.F. 12 max ==

w

Mt

Yσ

As tabulated in Table 14 above, by substituting w = 2.8 m and σY = 690 MPa into the

above equation, the minimum thickness of the platform is

m) .82Pa)( 10690(

m)N 775.449(126

m 101.67 3−×=×

⋅=t

Based on the two values of minimum thickness of the platform required obtained

from above calculations, and since the minimum thickness of the platform is seems to be

thicker for the case of lifting mechanism is fully-lowered as compared to the fully-lifted

position, therefore, the minimum thickness of the platform is found to be t = 1.67 mm.


Due to the fact that the minimum thickness of the platform is relatively flimsy, the

platform can be reinforced by mesh provided on the surface so that the applied loading

can be distributed.

11.7 Bending Moment and Deflection (Scissor-lift Legs)

Apart from the thickness of the platform required in order to sustain the huge

loading exerted from the car, another significant portion in which detail analyses should

be taken into considerations is the cross-sectional area of the scissor-lift legs. The

minimum cross-sectional area of the scissor-lift legs can be determined by similar

procedures employed in the determination of minimum thickness of platform as worked

in Section 11.6. Since all the loading applied onto all the scissor-lift legs are identical and

only normal components are contribute to the occurrence of deflection, therefore, only

one of the scissor-lift leg is considered to find the minimum cross-sectional area.

Bending Moment and Deflection for Leg 1


Based on the free body diagram as shown in Figure 34 above, the magnitudes of

nomenclatures are tabulated in Table 3 below.

Table 15: Magnitudes of Nomenclatures in Figure 10


Length of the scissor-lift leg, L 2.9 m


θmin 1.7°

θmax 20.9°

In order to select the reaction force of larger magnitude, the angle at which the lifting

mechanism is at the highest and lowest positions are taken into considerations. As shown,

only forces that are normal to the scissor-lift leg are analyzed, this is due to the fact that

only vertical forces contribute to the deflection of scissor-lift leg.


Table 16: Magnitude of Ay', J1 and F'CD at θ = 1.7 and 20.9 Degrees

Angle (Deg.) θcos8

WAy =′ θsec

81

WJ = θcos

8

WFCD =′

θ = 1.7° 3748.349 N 3751.651 N 3748.349 N

θ = 20.9° 3503.267 N 4014.111 N 3503.267 N

By comparing the magnitude of forces as tabulated in Table 16 above, the forces acting

on Leg 1 at angle of 1.7 degrees has been selected for the analyses of bending moment

and deflection for Leg 1 due to the larger value. Based on the free body diagram as

shown in Figure 34 and Table 16 above, the moment function can be expressed by

singularity function as follows:

( ) mN 45.1651.3751349.3748 ⋅−+−= xxxM


( )

mN 45.165.3751349.37481

2

2

2

2

⋅−−=

−=

xxdx

ydEI

xMdx

ydEI


3

21

33

2

1

22

mN 45.1275.6257248.624

mN 45.1825.18751745.1874

⋅++−+=

⋅+−−=

CxCxxEIy

Cxxdx

dyEI


[x = 0, y = 0]:

( ) ( ) 00007248.6240 221

3 =⇒+++= CCC

[x = 2.9 m, y = 0]:

( ) ( ) ( )

2559.5911

9.245.1275.6259.27248.6240

1

1

33

−=

++=

C

C

Hence,

333

222

mN 5911.25945.1275.6257248.624

mN 5911.255945.1825.18751745.1874

⋅−−+=

⋅−−−=

xxxEIy

xxdx

dyEI


For maximum deflection, 0=dx

dy

( )

m 8126.1

0178.98558925.54396505.1

05911.255945.1825.18751745.1874

2

22

=

=−+−

=−−−

x

xx

xx

At x = 1.8126 m,

( ) ( )m 4954.69641

8126.1maxEI

xyy −===

The negative sign in the maximum deflection above indicates that the leg 1 is deflected

upwards. Therefore, the maximum bending moment is

( )( ) ( )[ ]

mN 5433.9087 ⋅−=

⋅+−=

==

mN 3626.0651.37518126.1349.3748

8126.1max xMM

Since the cross-section of the scissor-lift leg is square, therefore, the length of the side of

the square cross-section is

m 109.72133−×== 3

max12

Y

Mt

σ

Computer Aided Engineering (CAD) and Prototyping Page 56 of 78

12.0 Computer Aided Design (CAD) and Prototyping

What is CAD (2012) mentioned that computer aided design (CAD) is a form of design in

which people work with computers to create ideas, models, and prototypes. Designers can also

move design elements around and run the design through software programs which can

determine whether or not the design is structurally viable. According to What is CAD (2012),

CAD can also be used to design structure, mechanical components, and molecules, among other

things.

There are few advantages of the utilization of CAD in the design process as follows:

• Prototypes need not to be built to demonstrate a project and its potential as 3D modelling

program could show how the system looks and works and it allows endless variations and

experiments to show how the look and function could be altered.

• Time expenses could also be cut down as it takes a long time to build prototype.

• The reduction of cost could also be done as the models could be simulated using software.

• Allows endless variations and experiments to show how the look and function could be

altered.

12.1 Prototyping

Prototyping is a phase of design processes in which a demo of a new product is

generated. It acts as a significant role in the design process as uncertainties in the design

project could be prevented and minimized. Prototyping can be grouped into two major

categories such as physical prototype and analytical prototype. Physical prototype is a

scaled-down model in which various experiments and testing can be conducted to

observe and examine the relationships between each parameters. On the contrary,

analytical prototype is a representation of actual model in non-tangible manner such as

computer simulations or mathematical equations used to describe the physics occurred.

Due to the financial constraints and costly expenses in terms of fabrication costs,

analytical prototype has been selected in the design of 3S Parking System.

12.1.1 Analytical Prototyping

The analytical prototype is modeled and simulated by using one of the

commercial software that had been extensively utilized in computer aided design

which is SolidWorks 2012. The prototyping of different parts and components of

3S Parking System are done by using SolidWorks and analytical prototypes are

depicted in pictures below.


Figure 35: 3D Model of 3S Parking System (Fully-lowered)

Figure 36: 3D Model of 3S Parking System (Fully-lifted)


Figure 37: The Single Acting Single Rod Hydraulic Cylinder

As shown in Figure 37 above, the single acting single rod hydraulic cylinder. The

working fluid of the hydraulic cylinder will act on one side in which the piston is retracting. In

other words, the force will be exerted as the piston is retracting. The retraction of the piston will

cause the lifting of the platform, thus force is needed in this operation. On the other hand, the

lowering operation of the whole system will cause the piston to extend. This process does not

require too much to be exerted. Thus we choose single acting cylinder for this application.


Figure 38: The Scissor-lift Mechanism (Lifting Device) used in 3S Parking System


Figure 39: Fixed Ends of the Scissor-lift Mechanism

Figure 40: Roller of Scissor-lift Mechanism


Figure 41: Backup Battery for 3S Parking System during Power Cut

12.1.2 Detail Drawings of 3S Parking System

The detail engineering drawings are drawn by the aid of SolidWorks and are illustrated in the

following pictures.


Figure 42: Top, Side, Front and 3D Isometric Views of 3S Parking System


Figure 43: The Exploded View of 3S Parking System


12.2 Finite Element Analysis (FEA)

According to Dixit (2007, p. 1), finite element analysis is a numerical method that

has been extensively employed in solving complicated mathematical equations such as

non-linear partial differential equations that used in the description of physical

phenomenon and modeling of engineering problems.

Finite element analysis is introduced in the design due to the fact that it can

provides a good approximations to the solutions of partial differential equations in which

analytical solutions are difficult to obtained. The determinations of deflections as well as

bending moment in Section 11.2 are based on appropriate assumptions in which some of

the parameters which might consequence in inaccuracy of results are neglected. Thus,

finite element analyses by the aid of SolidWorks Simulation Study on the deflection of

platform as well as the entire structure of 3S Parking System are conducted. The

methodologies employed in the numerical analysis are illustrated in Figure 44 below.

Apart from that, in the product development process, it is used to predict what is

going to happen when the product is used. Finite element analysis (2012) also stated that

FEA works by breaking down a real object into a large number (thousands to hundreds of

thousands) of finite elements. The behaviour of each element could be predicted by using

mathematical equations. A computer then adds up all the individual behaviours to predict

the behaviour of the actual object. Therefore, through the employment of FEA, the cost

required in the design can be economized.

By using finite element analysis, the behavior of products affected by many

physical effects such as mechanical stress, mechanical vibration, fatigue motion, heat

transfer, fluid flow, electrostatics and plastic injection moulding could be predicted.


Figure 44: Methodologies of Finite Element Analysis


12.2.1 Deflection of Platform

Since the platform is modeled as a beam in the computation of deflection

in the detail design, therefore, in order to ensure and examine the position where

the maximum bending occurs, finite element analysis of the deflection of platform

is conducted. The deflection of platform is depicted in Figure 45 below.

Based on the results obtained from the SolidWorks FEA Simulations as

illustrated, the position where the maximum deflection occurred is approximately

at the mid-span of the platform which has the highest magnitude of –0.229 mm.

The negative sign indicates that the platform is deflected downwards due to

gravity. Therefore, it can be concluded that the minimum thickness of the

platform obtained from analytical solution is logic. Apart from that, the result also

manifested that the deflection of the platform is relatively small, and it implies

that utilization of the platform in 3S Parking System is free from the risk of harm.

Figure 45: Deflection Profile of the Platform Obtained from SolidWorks FEA Simulation


Figure 46: Side View of Deflection Profile of the Platform

12.2.2 Deflection Profile of Entire 3S Parking System

Moreover, the team also analyzes the deflection profile of the entire

system with same loadings applied in the analysis of deflection of platform. The

deflection profile of the entire 3S Parking system is illustrated in Figure 47 below.

Based on the deflection profile obtained from SolidWorks FEA

Simulation as illustrated in Figure 47 below, the maximum deflection occurs at

somewhere around the mid-span of the platform which has a magnitude of

approximately 0.411 mm. Hence, it can be concluded that safety can be ensured

and guaranteed through the employment of scissor-lift legs with minimum cross-

sectional area obtained from the manual calculations.


Figure 47: Deflection Profile of the Entire 3S Parking System

Value Engineering Page 69 of 78

13.0 Value Engineering

Value engineering (VE) is a systematic process which mentions the functional values of a

particular product. Value engineering is performed to enhance the performance of the product

with reference to existing design and also to reduce cost. This could be the justification of the

product to be smart, sustainable, and safe.

Table 17: Value Engineering for 3S Parking System

Component Function Value Cost (RM)

Original Redesign

Caster wheel To support between the platform and the

base Medium 319.20 201.60

Platform To place the car parked on the top surface High 17100.00 9900.00

Base To support for the whole system as well as

the hydraulic system and scissor lift High 2880.00 1440.00

Hydraulic

cylinder

To provide mechanical force and sustain the

scissor lift up or down High 1200.00 608.00

Scissor lift To lift the platform and object (automobile)

up to a desired height High 1080.00 576.00

Control box To control the hydraulic cylinder support Medium 600.00 600.00

Hump To prevent the automobile slipping Low 90.00 45.00

Proximity

sensor

To prevent the failure when the switch of

remote control mistaken pressed Medium 3.00 3.00

Total Amount 23272.20 13373.60

According to Table 17, the price is estimated to be RM13373.60 as the prices in Table 17

are estimated based on the current market price. The price of the material will be reduced to at

least 20 – 35% of the redesign price when the product is manufactured in bulk.

Design for Manufacturing (DFM) Page 70 of 78

14.0 Design for Manufacturing (DFM)

Design for Manufacturing emphasize on the cost reduction of the whole system while the

quality is maintained. The cost reduction can be accomplished by reducing the number of parts

hence, the manufacturability can be enhanced. The product created through the utilization of

DFM technique can be easily manufactured and the manufacturing cost is affordable as well

(Chang et al 1998).

As addressed by Ulrich and Eppinger (2004), the 5 Steps Approach is introduced to

minimize the cost of manufacturing while the ease of manufacturing of a certain product is

improved.

Figure 48: 5 Steps Approach

Figure 48 above illustrates the phases of 5 Steps Approach which is implemented by the

team. The cost of the whole system is based on the number of parts and components of the entire

system, the assembly processes as well as the other expenses necessary for the production. The

implementation of DFM in our design process will only affect the total cost of the product while

the quality is maintained.


Table 18: Design for Manufacture

Item No. Component Standard

component

Custom

Component Material Quantities

Cost/Unit

(RM)

(Low Price)

Cost/Unit

(RM)

(High Price)

1 Platform - × ASTM A709 1 9995 17275

2 Scissor Lift Bar - × ASTM A709 16 45 67.5

3 Wheel × - - 16 12.5625 12.5625

4 Shaft for bar (short) - × ASTM A709 8 2.425 2.9575

5 Pin 1 - × ASTM A709 8 2.425 2.9575

6 Pin 2 - × ASTM A709 4 1.2125 1.47875

7 Base - × ASTM A709 2 720 1440

8 Pin 3 - × ASTM A709 4 1.2125 1.47875

9 Hydraulic Support - × Maple Wood 4 223.5 636

10 Circlip × - - 24 3.67 4.41

11 Hydraulic Cylinder × - - 4 152 300

12 Hydraulic Piston

13 Control Box × - - 1 600 600

14 Ramp - × - 2 454.5 1156

15 Battery × - - 2 250 350


Table 19: Cost Reduction

Item No. Component

Initial

Cost

From

BOM

(RM)

Reduced Costs

of Component

by Percentage

(%)

Reduced Cost

of Assembled

Component

Reduced Cost

of Supporting

Production

How the Cost is

reduced? Reason

1 Platform 9995.00 15 - - Thickness reduction

Maximum thickness

is employed, but

actual usage do not

really need such

thickness

2 Scissor Lift Bar 720.00 - - - - -

3 Wheel 201.00 8 - - Use Wheels That Is

Cheaper -

4 Shaft for bar (short) 19.40 - - - - -

5 Pin 1 19.40 - - - - -

6 Pin 2 4.85 - - - - -

7 Base 1440.00 10 - - Decrease In Thickness

Thickness can be

further reduced so

that the cost can be

economized

8 Pin 3 4.85 - - - - -

9 Hydraulic Support 894.00 20 - - Use Another Type Of

Wood

Wood used is Hard

Maple. Another

type of wood could

be used to substitute

it

10 Circlip 88.08 - - - - -


Table 20: Cost Reduction (Continued)

Item

Number Component

Initial

Cost

From

BOM

(RM)

Reduced Costs

of Component

by Percentage

(%)

Reduced Cost

of Assembled

Component

Reduced Cost

of Supporting

Production

How the Cost is

reduced? Reason

11 Hydraulic

Cylinder

608.00 5 - - Different

Manufacturer

There are various

manufacturer which

provide similar

cylinder that we

need 12

Hydraulic

Piston

13 Control Box 600.00 - - - - -

14 Ramp 909.00 30 - - Different Material

the cost can be

reduce by using

material with a

cheaper cost

15 Battery 500.00 5 - - Different

Manufacturer Different Brand


Table 18 is constructed based on the components of the finalized model. The entire

system encompasses of 14 components. The hydraulic cylinder and piston are drawn separately

so that animation can be done with minimum obstacles. Therefore, the hydraulic cylinder and

piston can be counted as one component. Some of the component employed in the design can be

found in the market whereas some of it requires parts customization. The costs can be greatly

reduced if large amount of off-the-shelf components are purchase together. On the contrary, the

cost required for the custom-made parts or components are relatively higher as compared to

those parts can be found in market. This is due to the fact that raw material is required for the

customization of parts and components. Besides, Table 18 also provides the cost estimation of

each parts and components according to the market price available. As listed in Section 13.0, the

cost estimated is approximately RM 13,000.00 whereas the estimated cost in DFM is

approximately RM 16,000.00. The deviation in the costs estimated is caused by distinct

methodologies employed in the cost estimations. Whereby, the costs of listed components in

value engineering and DFM are obtained from the costs of the parts that estimated earlier and

Bill of Material generated by SolidWorks respectively.

Both the Table 19 and 20 listed the components or parts employed in the design as well

as the corresponding reduced costs in terms of percentage. The alternatives used in the cost

reduction are mentioned and the reasons are listed as well. The reduction percentage is based on

the possible alternatives and solutions that are available in the existing market. Since the parts

and components produced by SolidWorks are the minimum, thus no further reduction in the

number of parts required can be conducted.

Safe Design Page 75 of 78

15.0 Safe Design

Safety is a very important aspect that needs to be considered when designing a system or

product. Safety is one of the important factors to produce a product; it affects the trust of the

customers towards a product. The 3S Parking system will considered a lot of safety aspects as

the product is for household usage.

The material used to construct the whole system is ASTM A709 which is a high strength

low alloy steel. This material belongs to a group of alloy steels named HSLA (High-Strength

Low Alloy). HSLA was also known as micro-alloyed steels as the alloying element such as

carbon, manganese, vanadium, silicon, chromium and niobium. HSLA main properties are the

light weight feature as compared to plain carbon steel. For structure design, it is good in terms of

corrosion resistance and high yield strength as well as high in tensile strength. The properties of

HSLA turn out to be the most suitable materials used for this product at such it had corrosion

resistance.

For the hydraulic cylinder used, there will be four hydraulic cylinders in total. Two of the

cylinders will be installed side by side in opposite direction, and then is installed on one side of

the whole system. The two cylinders will be installed on the hydraulic support so that the force

exerted by the cylinder will be forced horizontally so that it won’t bend or deflect that easily.

One of the hazards that might rise up is corrosion of the hydraulic cylinder, in layman’s term rust.

As this unit might be used in outdoor and indoor environment, thus damage experienced by the

hydraulic cylinder might due to excessive exposure to sunlight and rain for outdoor environment.

Indoor usage might reduce the occurrence of the damage to the whole system. Outdoor usage can

cause the corrosion to the parts on the outer surface of the cylinder such as the bolts and other

part expose to the environment. When hydraulic cylinder is damage there might be some

possibilities of it, such as oil leakage for the hydraulic oil which is used to power the whole

hydraulic system, rust of the fasteners affects the movement of the cylinder and so on. The

working fluid of the hydraulic cylinder leakage might also lead to environment contamination or

environment pollution.

In order to solve this problem, it is advisable that the maintenance is done frequently so

that the damage experience by the hydraulic unit will not affect the performance of the whole

system. Such maintenance can reduce the possibilities of oil leakage. The hoses will be

periodically checked so that the leakage by the hoses will be reduced as well.

On the contrary, the platform itself needs some safety feature to ensure the stability of the whole

system and the safety of the vehicle parked on top of the platform. Hence, humps are installed on

top of the platform as to ensure that the vehicle parked on the platform does not have any chance

of slipping. The humps are installed in such that the tyres of the vehicles can be positioned

between two humps. This means that the tyres are situated firmly on the platform by the help of

the humps.

Another safety feature include in this system is the installation of sensor to ensure the

safety of the vehicle of the customer. The sensor is installed at the bottom face of the platform to

sense the availability of car parked at the lower compartment of the system to prevent from being

crushed by platform. This is a fool-proved system that has been introduced to prevent accidents

from happening. For example, if the customer accidentally pressed the “down” button on the

control unit when there is a vehicle parked at the lower compartment of the system, the sensor

will sense the presence of the vehicle and directly implement the emergency stop to stop the

platform from moving. There will also be another sensor installed around the top compartment as

to ensure that the vehicle is parked correctly at the given space. Due to the size of the platform,

Safe Design Page 76 of 78

where the platform is originally designed to only support the wheel base as to reduce space

consumption. This sensor’s function is to alert users the appropriate moment to stop their car

which prevents it from slipping down during lifting.

In the system design of the product, safety aspect is heavily look and take consideration of to

prevent accidents from occur as safety features is the priority features that determine the

purchase decision of customers. Therefore, a good safety feature product will results in a bright

market. In other words, an excellent product with no market value will be considered as failure

product.

Discussion Page 77 of 78

16.0 Discussion

The primary objective of this project is to develop a novel and innovative parking system

for customers who are confronted with the problem of insufficient parking space to park their

extra cars in normal residential housing area that has confined and limited parking spaces. Based

on the problem statement, 3S Parking System is designed in which it encompasses of a platform

which can be lifted and lowered by the employment of scissor-lift mechanism that is powered by

hydraulic cylinders. Hydraulic cylinder is selected to provide lifting due to the green concept it

possesses as electricity is used as the power source instead of power generation by charcoal fuels

and diesel which might leads to environmental degradation.

In order to design and develop a quality product that will satisfy the demands and needs

of customers, a methodology which is so-called the house of quality from quality function

deployment has been introduced whereby the relationship between the customers attributes and

engineering characteristics can be clearly visualized. Various conceptual designs are then

generated and developed based on the need statement of customers. The best and ideal concept is

selected through the evaluation processes such as concept screening and concept scoring as the

pros and cons associated with each concept can be assessed and analyzed. Therefore, the

finalized concept that decided by the team is the 3S Parking System that encompasses of dual

two-stage scissor-lift mechanism which located at each side of the platform. Besides, the

hydraulic cylinder is positioned at the middle section due to higher mechanical efficiency it

produced.

Since the development of 3S Parking System is to provide a smart, safe and sustainable

parking alternative, therefore the design of the product must be free from the risk of harm. In

order to ensure safety utilization of the product, detailed engineering analysis has been

conducted. The Maximum Bending Stress Theory from solid mechanics is utilized in the

determination of minimum thickness of the platform as well as the minimum cross-sectional area

of the scissor-lift legs to prevent from mechanical failures. Appropriate and logical assumptions

have been made to ease the process of calculations such as the platform of the 3S Parking

System is modeled as a beam in the analysis. This is due to the lengthy and tedious calculations

need to be performed so that the analytical solution of the partial differential equation that

governs the deflection phenomenon of a flat plate can be obtained. Once the hydraulic force

required to power the scissor-lift mechanism is known, hydraulic cylinder is selected. Besides,

hydraulic cylinder calculations are performed so that the properties and dimensions of cylinder

can be determined.

With all the dimension of each of the components in the entire 3S Parking System known,

prototyping of the design is conducted. Analytical prototype is selected in the design of 3S

Parking System due to restriction of financial constraints and costly expenses in terms of

fabrication cost. Finite element analysis (FEA) is introduced as good approximations to the

solutions of partial differential equation that used in the governing of deflection profile of plate

are provided. The results obtained from the SolidWorks FEA Simulations are then compared

with the results obtained from the manual calculations in Detail Design. By comparing the

results obtained from both methodologies, it can be concluded that the deflection of platform as

well as the scissor-lift legs are logic as expected before the simulation is conducted.

Conclusion Page 78 of 78

17.0 Conclusion

In general, 3S Parking System that will satisfy the demands of customers is successfully

developed. But, there is still some space in which improvements can be made such as double

acting hydraulic cylinders will be implemented so that the mechanical efficiency can be further

increased as well as leads to cost reduction. Apart from that, more meetings should be conducted

as various ideas and concepts in which the performance of the entire system can be enhanced.

Through this design project, various techniques and methodologies that have been

extensively employed in engineering designed such as the application of quality function

deployment in the determination of characteristics, weighted objectives method used in concept

selection, and design for manufacturing used in cost reduction are learned. As in real-life

applications, these methodologies can be implemented so that the design of product can meet the

customer’s requirements.

The project team is divided into multi-disciplinary group as some of the members will

focus on certain part based on the technical knowledge each possesses. Through the design

processes, soft skills that have been extensively applied in management such as team work is

developed. This will assists each of the team members to be well prepared to the future design

environment.

In conclusion, the implementations of 3S Parking System provides a smart, safe and

sustainable alternative to household users, who are confronted with problems of insufficient

parking spaces, in which the primary objective of this design project is attained. Besides from the

primary objective of this design, the learning objectives of this unit (Mechanical System Design)

such as the appreciation of principle of system design, estimating the reliability of mechanical

system are accomplished as well.

Recommendations Page 79 of 78

18.0 Recommendations

For future design, double acting double rod hydraulic cylinder will be introduced to

provide lifting and lowering of scissor-lift mechanism since mechanical efficiency can be

enhanced and the cost of the design can be significantly reduced. Apart from that, manual

operations will be included in the design as well. This is due to the fact that as mentioned in the

Concept Generation Section, lifting of the platform is unable to attained during power cut,

therefore, manual operation in the lifting will be introduced. This can be done through the

employment of gearing mechanism or gear train to control the vertical movement of the scissor-

lift mechanism. Besides, better appearance as well as parts with lower price will be introduced so

that it can be affordable by each of the household users.

Acknowledgement

Acknowledgement

The phases in designing and implementing a new product is a time-consuming process of

which problems arise from various aspects should be taken into consideration, and it is never

easy as this may end up with lot amount of success and failure in certain superfluous conditions

which might results in disappointment and frustration of people around. Therefore, the team

would like to express their heartfelt gratitude to Dr. Soon Kok Heng who has been there to guide

us throughout the entire project and has believe in us that we possesses the ability to progress

with integrity. Apart from that, special gratitude also extended to Dr. Ha How Ung who has

spent his precious time to assists us in the calculations in the detail design. Besides, deepest

gratitude also expressed to Mr. Wong Soon Jin and Ms. Melissa Augustine for providing the

team guidance in the concept generation when we are running out of ideas. Lastly, we would like

to thank all the respondents and participants of the online survey for spending their precious time

in answering the questions in the survey.

References

References

Beer, FP, Jonhston, ER, DeWolf, JT & Mazurek, DF 2012, Mechanics of Materials, 6th

edn.,

The McGraw-Hill Companies, Inc., New York.

Benham, PP, Crowford, RJ & Armstrong, GG 1996, Mechanics of Engineering Materials,

Pearson Prentice Hall, England.

Currency converter n.d, gocurrency.com, viewed 4 December 2012,

<http://www.gocurrency.com>

Dixit, US 2007, FINITE ELEMENT METHOD: AN INTRODUCTION, Department of

Mechanical Engineering, Indian Institute of Technology Guwahati-781 039, India.

Finite element analysis (2012), Autodesk Inc, viewed 3 December 2012,

<http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=17670721 >

Mago, N & Hicks, S n.d., FINITE ELEMENT ANALYSIS What is it and how can it help your

company?, HERA Innovation in Metals

Shariff, NM 2012, Private Vehicle Ownership and Transportation Planning in Malaysia, 2012

International Conference on Traffic and Transportation Engineering (ICTTE 2012)

IPCSIT Vol. 26, IACSIT Press, Singapore.

Smith, GP 2007, Morphological Charts: A Systematic Exploration of Qualitative Design Space,

A Thesis Presented to the Graduate School of Clemson University In Partial Fulfillment

of the Requirements for the Degree of Master of Science Mechanical Engineering,

Clemson University.

What is CAD (2012), Conjecture Corporation, viewed 3 December 2012,

http://www.wisegeek.com/what-is-cad.htm

William, D & Callister, Jr 2007, Materials Science and Engineering An Introduction, 7th

edn.,

John Wiley & Sons, Inc., United States of America

Ventsel, E & Krauthammer, T 2001, Thin Plates and Shells Theory, Analysis, and Applications,

Marcel Dekker, Inc., United States of America.

Zakuan, NM, Yusof, SM & Shamsudin, S 2007, Implementation of Quality Management

Practices in Malaysian Automotive Industries: A Review, Regional Conference on

Engineering Mathematics, Mechanics, Manufacturing & Architecture (EM*ARC) 2007,

Advanced Processes and System in Manufacturing (APSIM) 2007.

Appendices

Appendices

Appendices

Appendix 1 – Project Plan and Execution (Gantt chart)

Appendices

Appendices

Appendices

Appendices

Appendices

Appendices

Appendices

Appendices

Appendix 2 – Presentation PowerPoint Slides

Appendices

Appendices

Appendices

Appendices

Appendices

Appendices

Appendices

Appendices

Appendices

Appendices

Appendices

Appendices

Appendix 3 - Tables of Typical Properties of Selected Materials Used in Engineering

Appendices

Appendix 4 – Concurrent Engineering Write-up

Students are divided into 2 different groups one that practice the sequential product

development process and another that uses concurrent engineering. The task of manufacturing

aeroplane is given to both groups. Through the different practice of the engineering terms

comparisons of it is made based on the results obtained. For our group, which practice the

concurrent engineering had allowed the changes in the hierarchy of an organization. Group

members are divided into smaller group that focus on different parts like the design,

manufacturing, purchasing and marketing. Each small group will be focusing on their parts and

work parallel from the start with other groups. In the process of it till the end of the tasks the

concurrent engineering will be putting the design process, manufacturing and marketing

development together to generate the outcome. From the results, it can be seen that concurrent

engineering is faster in terms of time which is ideal for fast pace of technology nowadays as it

had shorter time to market. However, there is down part that concurrent engineering faces than

the sequential product development process as the collaboration between the groups is less and

therefore the marketing and manufacturing issues is less considered.

Appendices

Appendices

Appendices

Appendices

Appendix 5 – Design for Manufacturing Exercises

Appendix 6 – Safe Design Case Studies and Exercises

According to safety principles of safe design, safe design is everyone’s responsibility. The

responsibilities for safe design rest with those persons have control or influence over the design.

In this case, lack of communications happen from the designer to the end user as the user should

aware of any risk that may affect their health and safety. Besides, duties of different groups of

people involved in the workplace have played an important role to ensure the health and safety in

a workplace. Therefore, the maintenance team did not achieve to the due diligence as they should

hold the duty of care to ensure the machine is free from blockages before the usage in the future.

Apart from that, the trainer also has to be reasonably practicable which the knowledge of

severity of the hazard should be taken into consideration. The trainer should checks the safety of

the machine before it reaches to the end user. Other than that, the employer did not achieve their

duty of care on the risk management as they should follow up the duty of maintenance team to

minimize the risks facing by the end user. Moreover, the distributor also has to take

responsibilities on the trading of their business as they are required to provide clear information

associated with the risk management of their selling product to their customer who is the

employer of the company in this case. However, the manufacturer and designer have control and

influence over the design of machines and thus, hold the legal responsibility for the failure of a

machine. The sate design principles should be implemented on the design of the machine to

ensure that hazards are identified as early as possible and that they are designed out, the risks are

responsibly managed throughout the entire life cycle. The design should also meet an engineer’s

responsibilities for sustainable, ethical and socially responsible practice.

Documents

HES4350 Mechanical System Design, Semester 2 2012, Project Report (3S Parking System)