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ADVISOR: DR. LEE

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Page 1: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and

ADVISOR: DR. LEE

Page 2: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and

TABLE OF CONTENTS

Abstract 3Introduction 4Objectives 5Inventor Professional 2011 6Frame Analysis 8Results 9

Next Semester 11Deliverables and Time-line 12

Page 3: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and

Abstract

In this project I had to design a frame for the SAE baja competition from the

ground up. I then had to read the rulebook and draft a basic shell frame design using cad

software. The goal was to keep the frame both light and strong, while also keeping the

cost down. After I come up with frame design and it is drawn in cad I can use the FEM

software (Inventor) to run stress tests in order to see the smallest size pipe that would

satisfy the load condition acting on the frame. Also the stress test will help in the

placement of supports for the basic shell. I will run stress test on ranging from 1-1.25

diameter with varying thicknesses, to find the smallest acceptable size.

Page 4: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and

Introduction

The Baja SAE project is a competition that simulates real-world engineering

design projects and their related challenges. Engineering students are given the task to

design and build an off-road vehicle that will survive the severe punishment of rough

terrain.

The object of the competition is to provide SAE student members with the

challenge of introducing a new product to the consumer industrial market. Students must

function as a team to not only design, build, test, promote, and race a vehicle within the

limits of the rules, but also to generate financial support for their project and manage their

educational priorities. All vehicles are powered by a ten-horsepower Intek Model 20

engine donated by Briggs & Stratton.

Page 5: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and

Objective

The objective of my part of the baja project is to design and construct the

chassis/frame of the vehicle from the ground up. Some challenges are I need to keep the

frame both light and strong while trying to keep the cost down. I will need to choose the

proper frame diameter by first exceeding the SAE strength standard while still having an

advantage in weight reduction. Finally I will test the whole design by doing a stress

analysis, to see if the design will satisfy the load conditions, if not I will choose different

size tubing until I find the smallest acceptable size.

I will have to, first, design the overall shape by using the guidelines of the rules

and then find ways to make the frame both stronger and lighter. I will collect data for

each analysis and then add supports to my frame as needed.

Page 6: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and

Inventor Professional 2011Inventor 2011 is the cad program I used for my project to draft the design of the

frame. I used this software because it is similar to Auto Cad, but it has more features like

the FEM (finite element method) software that is already imbedded in Inventor

professional 2011.

To draw the frame in Inventor you must first draw the frames skeleton. To do this

you must draw a series of drawings in 2D sketches on different planes then go back and

connect all the 2D drawings with 3D lines. This is what it will look like:

Page 7: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and

All these lines will become the frame once the frame generator command is used.

After the command this is what it will look like:

With this command I constructed frames using tubing ranging from 1 inch to

1.25inches in varing thicnesses, so that I could run stress test to find the smallest size

tubing that would still be safe. The frame I designed was 89 inches long and at its widest

point was 37 inches. The rules stated that the length is not limited but the width could

only be 64 inches at its widest, so I left lots of room for the suspension an tires.

Page 8: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and

Frame Analysis

For the analysis the weight of the driver (180 lbs) and the weight of the engine (75

lbs) were added where they will connect to the frame. I ran the analysis in the FEM

software on the different tubing sizes ranging from 1x.133- 1.25x .191 to find the

smallest diameter pipe that would satisfy max stress =Sy/8. I was going to use Comsol for

the FEM software but I had trouble importing my file, so I just used the one in Inventor.

After the first run I had to add supports on the frame because the max stress was greater

than the design stress. I did this multiple times until I finally got the design to pass the

test with a small diameter pipe.

Page 9: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and
Page 10: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and

Results

The smallest size pipe that would satisfy the load condition was the 1x.133 mild

steel. Although I believe I could have gotten it to be satisfied with a thinner wall

thickness, but the material library in Inventor was limited. The maximum stress that the

design could take is Sy/8= 30043.54/8= 3755.44 psi. I found this by dividing the Yield

Strength by a design factor of 8, which is for a repeated load.

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After presenting my project, some changes were needed to be made to the frame to

make it more symmetrical. Also, I had to relocate the frame constraints to where the

suspension would connect.

Page 12: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and

Name Minimum MaximumDisplacementDisplacement 0.000 in 0.012 in

ForcesFx -46.770 lbforce 98.156 lbforceFy -44.424 lbforce 48.375 lbforceFz -100.394 lbforce 83.655 lbforce

Mx -227.179 lbforce in

273.332 lbforce in

My -262.163 lbforce in

337.103 lbforce in

Mz -85.431 lbforce in

85.277 lbforce in

Normal StressesSmax -78.784 psi 3597.977 psiSmin -3661.036 psi 62.695 psiSmax(Mx) 0.000 psi 2059.008 psiSmin(Mx) -2059.008 psi -0.000 psiSmax(My) 0.000 psi 2539.392 psiSmin(My) -2539.392 psi -0.000 psiSaxial -203.417 psi 169.501 psiShear StressesTx -187.950 psi 394.450 psiTy -178.521 psi 194.400 psiTorsional StressesT -321.777 psi 321.196 psi

Next Semester

For next semester I will tie up all the loose ends of the frame analysis, then I will

construct the frame using the design I have come up with.

Page 13: SAE BAJA PROJECTcsit.selu.edu/~csit/seniorprojects/Seniorprojects2011/... · Web viewThe Baja SAE project is a competition that simulates real-world engineering design projects and

Deliverables and Time-line

October 17- a basic design for the frame.

November 7- have the design in inventor, select diameter tubing and do stress

analysis.

November 21- alter design if needed

December 4 - Gather materials and start construction of the frame

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