2008-2009 Design and Fabrication of a SAE Baja Race Vehicle A Major Qualifying Project Report Submitted to the Faculty of WORCESTER POLYTECHNIC INSTITUTE In partial fulfillment of the requirements for the Degree of Bachelor of Science By: ____________________________ Derek Britton ____________________________ Jessy Cusack ____________________________ Alex Forti ____________________________ Patrick Goodrich ____________________________ Zachary Lagadinos ____________________________ Benjamin Lessard ____________________________ Wayne Partington ____________________________ Ethan Wyman Date: April 29,2009 ____________________________ Kenneth Stafford, Advisor ____________________________ James Van De Ven, Advisor ____________________________ Torbjorn Bergstrom, Advisor 1 Table of Contents List of Figures ..................................................................................................................... 5 List of Tables ...................................................................................................................... 9 Introduction ....................................................................................................................... 10 Design Goals ..................................................................................................................... 11 Chassis .............................................................................................................................. 13 Ergonomics.................................................................................................................... 13 Seat ............................................................................................................................ 15 Materials ........................................................................................................................ 16 Thermal Processing ....................................................................................................... 18 Stress Analysis .............................................................................................................. 21 Load Scenario Determination .................................................................................... 21 Input Load Determination ......................................................................................... 24 Finite Element Analysis............................................................................................. 26 Chassis Optimization..................................................................................................... 29 Tube Size Selection ................................................................................................... 29 Weight ....................................................................................................................... 30 Geometry ................................................................................................................... 30 Strengthening Mechanisms ........................................................................................... 31 Flared Holes ............................................................................................................... 31 Gussets ....................................................................................................................... 32 Stressed Body Panels ................................................................................................. 33 Body Panel Selection .................................................................................................... 39 2 Fabrication ........................................................................................................................ 41 Chassis Fabrication ....................................................................................................... 41 Frame Table and Coordinate system ......................................................................... 41 Bending ......................................................................................................................... 42 Notching ........................................................................................................................ 42 Welding ......................................................................................................................... 42 Suspension ........................................................................................................................ 44 Front Suspension ........................................................................................................... 44 Preliminary Design Parameters ................................................................................. 44 Component Design ........................................................................................................ 47 Knuckle ...................................................................................................................... 48 Control Arms ............................................................................................................. 59 Front Hub ................................................................................................................... 62 Rear Suspension Design and Analysis .......................................................................... 64 Rear Suspension Manufacturing ................................................................................... 73 Wheel Design and Analysis .............................................................................................. 75 Moment of Inertia.......................................................................................................... 75 Wheel Acceleration ....................................................................................................... 77 Wheel Fabrication ......................................................................................................... 84 Driver Controls ................................................................................................................. 87 Rack ........................................................................................................................... 87 Steering Wheel .......................................................................................................... 90 Pedals ......................................................................................................................... 90 Brakes ............................................................................................................................ 91 Brake Plate design ..................................................................................................... 93 3 Thermal Analysis of the Rear Disc ............................................................................ 94 Drive Train ........................................................................................................................ 98 Engine............................................................................................................................ 98 Maximum Power ........................................................................................................... 98 Drive Train Selection .................................................................................................... 99 Thrust and Accelerations Calculations ........................................................................ 100 Rolling Resistance Test ............................................................................................... 103 Air Resistance ............................................................................................................. 105 Drive Train Design ...................................................................................................... 111 Sprocket Design .......................................................................................................... 112 Manufacturing ......................................................................................................... 114 Intermediate Shafts ...................................................................................................... 115 Final Shaft ................................................................................................................... 117 Gear Frame Parameters ............................................................................................... 118 Bearing Housing .......................................................................................................... 123 Appendix A: Thermal Processing ................................................................................... 125 Appendix B: Input Load Determination ......................................................................... 128 Appendix C: FEA Results ............................................................................................... 133 Appendix D: Stressed Panel Analysis............................................................................. 138 Appendix E: Drive Train Calculations ........................................................................... 139 Appendix F: Camber Vs. Steering Angle ....................................................................... 140 Appendix G: Brake Calculations .................................................................................... 142 Appendix H: Chain and Sprocket Calculations .............................................................