Final Report Reinventing the Wheel Formula SAE Student Chapter California Polytechnic State University, San Luis Obispo 2018 Patrick Kragen [email protected] Ahmed Shorab [email protected] Adam Menashe [email protected] Esther Unti [email protected] CONTENTS Introduction ................................................................................................................................ 1 Background – Tire Choice .......................................................................................................... 1 Tire Grip ................................................................................................................................. 1 Mass and Inertia ..................................................................................................................... 3 Transient Response ............................................................................................................... 4 Requirements – Tire Choice ....................................................................................................... 4 Performance ........................................................................................................................... 5 Cost ........................................................................................................................................ 5 Operating Temperature .......................................................................................................... 6 Tire Evaluation ........................................................................................................................... 7 Lateral Force .......................................................................................................................... 7 Hoosier LC0 ........................................................................................................................ 8 18.0x6-10 Hoosier R25B ..................................................................................................... 9 13x6 Hoosier R25B ............................................................................................................. 9 Avon ................................................................................................................................... 9 Longitudinal Force .................................................................................................................10 Normal Load Sensitivity .........................................................................................................11 Relaxation Length .................................................................................................................12 Vehicle Integration .................................................................................................................14 Steering Effort ....................................................................................................................14 CG Height and Overturning ................................................................................................15 Aero ...................................................................................................................................15 Kinematics and Packaging .................................................................................................15 Camber and Toe Stiffness .................................................................................................15 Conclusion ............................................................................................................................16 Rim Width ..........................................................................................................................17 Background – Wheel Design .....................................................................................................20 Composites ...........................................................................................................................20 Relevant Efforts to Produce Carbon Fiber Wheels ................................................................20 Ohio State ..........................................................................................................................20 Kansas ...............................................................................................................................21 Cal Poly .............................................................................................................................21 TU and Joanneum Graz .....................................................................................................21 Industry ..............................................................................................................................22 Composites Manufacturing ....................................................................................................23 Requirements – Wheel Design ..................................................................................................24 Determining Tolerances ........................................................................................................25 Structures ..............................................................................................................................25 Loads .................................................................................................................................25 Analysis ....................................................................................................................................28 Methodology ..........................................................................................................................28 Hub Connection .....................................................................................................................29 Concept Designs ................................................................................................................29 Detailed Design..................................................................................................................32 Structural Analysis .............................................................................................................34 Final Design .......................................................................................................................36 Wheel Geometry ...................................................................................................................37 Stiffness Sensitivity ............................................................................................................37 Spoke Cross-Section .........................................................................................................39 Spoke vs. Plate Analysis ....................................................................................................41 Spoke Number ...................................................................................................................43 Barrel Shape ......................................................................................................................43 Number of Pieces ..............................................................................................................44 Preliminary Geometry Selection Summary .........................................................................46 Composites ...........................................................................................................................47 Detailed Stiffness Analysis ....................................................................................................49 Detailed Strength Analysis .....................................................................................................57 Post Manufacturing Trial Analysis ..........................................................................................60 Detailed Analysis Summary ...................................................................................................60 Valve .....................................................................................................................................61 Manufacturing ........................................................................................................................62 Manufacturing Process Selection .......................................................................................62 Tooling ...............................................................................................................................62 Insert Design ......................................................................................................................66 Post Machining ..................................................................................................................68 Center Insert Bonding ........................................................................................................68 Manufacturing Tests .................................................................................................................68 First Manufacturing Test ....................................................................................................68 Geometry Changes from First Manufacturing Test .............................................................73 Cure Cycle and Fiber Wetting ............................................................................................73 Second Manufacturing Test ...............................................................................................74