Senior Design 1Final Document

For2017 Baja Frame Design

Spring 2017

Southeastern Louisiana University

ET Department

Professor: Dr. Cris Koutsougeras

Advisor: Dr. Ho Hoon Lee

Kyle RichertMechanical Concentration

Alexandria WilliamsMechanical Concentration

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Table of Contents

Abstract Pg. 3

Project Description Pg. 4

Methods Pg. 4

Measurements Pg. 9

Reaction Forces Pg. 10

Other Teams’ Needs Pg. 11

Deliverables Pg. 11

Participation Pg. 12

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Abstract

The idea is to work in independent groups by dividing one complete design into four

smaller groups. These groups consist of designing the frame (our group), steering, powertrain,

and suspension. The goal of this project is to demonstrate mathematical and design skill learned

from prior coursework. Our frame group will accomplish the design of a BAJA frame using the

skills and knowledge we learned throughout the Engineering Program. Skills in the

understanding of stress and strain will be tested throughout the frame to ensure the frame is

structurally sound while communicating with the other teams to modify the frames to the specific

needs for all of the parts that it will include. The final design will be created on a computer

program called Solidworks for a visual look at the stresses throughout the frame.  

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Project Description

Our object was to design a Baja frame that is in compliance with the SAE 2017 Mini

Baja rules and regulations. Research, stress analysis, defining forces throughout the frame, and

implementing frame solutions in Solidworks are all used to ensure a complete safe frame design.

We worked closely with the suspension team, powertrain team, and in accordance with the

steering solution. The frame must be as light as possible to increase our Force in the equation

F=Mass X Acceleration. The accelerator is given in the project since the motor and drivetrain are

both regulations in the SAE 2017 Mini Baja rules. Thus, the only way to increase the project’s

velocity was to create the lightest frame possible while providing a safe and stable vehicle for the

driver. To ensure the safety of the driver, our frame design was created in Solidworks to check

the forces from a front impact, rear impact, and vertical crushes. The stability was ensured from

the design process of wheelbase measurements and center of gravity.

Methods

Using the computer program Solidworks, we first learned how to create meshes. These

meshes were put together using a 3D sketch to create lines that later become weldments. For our

weldments we chose 1” AISI 4130 Steel Pipe using normalizing at 870C to follow the Baja rules

and normalizing treated method to increase the yield stress. Once the weldments were in place,

we had to look at each joint to ensure proper fit. This was done with the trim/extract feature that

properly cuts the angles of the 1” pipes and welded them together. The frame was created using

step-by-step methods stated above and using the Solidworks stress analysis program using 400lbf

in the vertical or horizontal directions at the point being tested. The testing was done with the test

method at each stage of the framing build to see how exactly the frame was being affected by

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external forces from different directions. First, the bottom of the frame was built and tested.

Second, were the mounting areas for the suspension, steering, and power train then tested. Third,

the roll cage was designed and tested. Throughout the whole build, factors were kept in mind that

included 95% percentile of male’s measurements, safety impact factor, and disbursing stresses.

The 95% percentile measurements were used to design the length of the cab and steering.

Lengths for the driver’s legs, arms, sitting height, lumbar support, and 12” safety clearness above

the helmet were all used from the chart (Figure 1.1). Measurements were added with the theory

of a 6”-8” thick driver seat. Safety impact factor was used in the case of a front, rear, or vertical

impact to keep the driver safe. This was accomplished by constructing the frame with a more

solid inner frame, where the driver sits, and the outer frame absorb/disburse the energy

transmitted. The inner frame has cross members that transfer external impact forces around the

driver seat. The outer frame, where the control arms are, have minimal cross members that

crushes into itself then transfers remaining forces to the inner frame (Figures 1.2-1.4). The roll

cage was designed to help transfer front and rear impact but also stops the driver from becoming

injured in the case of a vertical impact (Figure 1.5).

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                                                     Figure 1.1

                       Figure 1.2                                                        Figure 1.3

                       

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                         Figure 1.4                                                        Figure 1.5

The frame also contains C-Channels for the mounting for the steering pinion, motor

mount, shock mounts, and foot petals. The steering location was chosen in the middle of where

the upper front control arms will be placed. The motor mount C-Channel is located center of

where the axle will go. Four vertical C-Channels were placed for the shocks and reinforced to

disburse the stress added onto the frame during operation. Testing proves that at full vertical

force, the reinforced C-Channel will disburse the force and no failure (Figure 1.6). The C-

Channels also act as a horizontal support for the out runners on the frame rails.  

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Figure 1.6

At the completion of designing the frame, weldment material was chosen and illustrated

(Figures 1.7-1.10). AISI 4130 Steel, normalizing at 870C was used because the Baja rules and

increased strength. Throughout the testing methods, the scale showed that the stresses on the

frame stayed down the yield strength design factor. Since the frame will be experiencing external

forces, the design factor was 2 and 4. The inner frame test results shows that the yield strength

divided by 4 was still lower than the result scale. The outer frame test results shows that the yield

strength divided by 2 was lower than the result scale. This was done so that the inner frame

would be stronger while the outer absorbs impacts in the case of a wreck.  

                            Figures 1.7

Safety Yield point: Where N=4

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66717.36/4= 16679.34psi

Measurements

                   Figure 1.8                                                        Figure 1.9

                                       Figure 1.10

Weight: Frame only- 292lbs

Center of gravity frame only: 292lbs at 43” from rear and 44” from front

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Reaction Forces:

The following calculations were done using the assumption of a 150lb driver, 50lb motor,

and suspension at 30 degrees. The stress analysis (figure 1.11) shows the frame is below the

yield/4 for safety factor.

Front tires- 184lbs total and 92lbs at each tire

Front suspension brackets- 80lbs in the Y direction and 46lbs in the X direction

Rear tires- 308lbs total and 154lbs at each tire

Rear suspension brackets- 133lbs in the Y direction and 77lbs in the X direction

Figure 1.11

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Other Teams’ Needs

Suspension: Eight 1” Steel tubing horizontally for upper and lower control arms and four 3” C-

Channels vertically for shocks.

Steering: Convex cross member attached on front roll cage for mounting steering wheel at 26”

high from bottom of the frame. 4” C-Channel mounted onto the front upper suspension supports

for rack and pinion.

Power Train: 4” C-Channel mounted onto the rear upper suspension supports for mounting of

motor. Larger rear opening gives clearness for axle travel.    

Deliverables

February 2017

Brainstorm ideas (Completed)

Design a frame using stress analysis (Completed)

March 2017

Create proposal and presentation (Completed)

Revise proposal and create rough draft (Completed)

Work with other teams and redesign frame (Completed

April 2017

Finalize proposal and general design (Completed)

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Run stress analysis in Solidworks computer program (Completed)

May 2017

Write proposal (Complete)

Present final presentation (May 5th)

Next Semester:

Construction of prototype

Fix any issues with frame if needed

Participation

Kyle Richert-

Understand how to create using reverse engineering

Stress analysis

Cost analysis

Finalize SolidWorks model

Alex Williams-

Material selection

Provide accommodations for other Baja components (powertrain, suspension, and

steering)

Design of mounting interfaces between Baja team groups

Together as a team-

Researched a metal material that complies with the SAE Mini Baja regulations

Researched and made rough draft design

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Created 3D model analyzing forces

Made adjustments throughout semester

Wrote the papers required, made powerpoints and participated in presentations

Wrote weekly/bi-weekly reports

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