Formula SAE Interchangeable Independent Rear Suspension Design Sponsored by the Cal Poly Formula SAE team A Final Report for Reid Olsen, FSAE Technical Director By: Suspension Solutions Design team Mike McCune - [email protected] Daniel Nunes - [email protected] Mike Patton - [email protected] Courtney Richardson - [email protected] Evan Sparer - [email protected] 2009 ME 428/481/470 Table of Contents Abstract ......................................................................................................................................................... 6 Chapter 1: Introduction ............................................................................................................................... 7 FSAE Team History and Opportunity ......................................................................................................... 8 Formal Problem Definition ...................................................................................................................... 10 Objectives/Specification Development ................................................................................................... 11 Chapter 2: Background ............................................................................................................................... 13 Solid Rear Axle Design ............................................................................................................................. 14 Tire Research ........................................................................................................................................... 15 Steady State Cornering Model ................................................................................................................ 16 Chapter 3: Design Development ................................................................................................................ 19 Suspension Geometry .............................................................................................................................. 20 Loading Conditions and Forces ............................................................................................................... 22 Space Frame Adaption ............................................................................................................................ 23 Differential .............................................................................................................................................. 27 CV Joints and Half Shafts......................................................................................................................... 28 Uprights ................................................................................................................................................... 30 Chapter 4: Final Design ............................................................................................................................... 33 Summary and model ............................................................................................................................... 34 Detailed Design Description and Analysis ............................................................................................... 36 Rear A-Arms ........................................................................................................................................ 36 Rear Rockers ....................................................................................................................................... 39 Shocks and the Anti-Roll Bar (ARB) ..................................................................................................... 40 Front Suspension Analysis and Redesign ............................................................................................ 41 Rear Frame Adaptation ....................................................................................................................... 43 2 Differential Choice and Mounting ....................................................................................................... 47 CV Joints, Half Shafts, Splines, and Axles ............................................................................................ 52 Spline Analysis ..................................................................................................................................... 52 Half Shaft Fatigue ................................................................................................................................ 54 Spindle Fatigue Sizing .......................................................................................................................... 55 Uprights ............................................................................................................................................... 57 Cost Analysis ........................................................................................................................................... 58 Manufacturing Plan ................................................................................................................................ 60 Chapter 5: Manufacturing Process ............................................................................................................. 61 Suspension: ............................................................................................................................................. 62 A-Arms................................................................................................................................................. 62 Rockers ................................................................................................................................................ 63 Push-rod’s/Tie-rods:............................................................................................................................ 64 Chassis ..................................................................................................................................................... 65 Drivetrain: ............................................................................................................................................... 67 Differential Inserts .............................................................................................................................. 67 Differential Axle Stubs......................................................................................................................... 68 Differential Uprights ........................................................................................................................... 68 Differential Half Shafts ........................................................................................................................ 69 Differential Drilling .............................................................................................................................. 69 Drive train Assembly ........................................................................................................................... 69 Uprights: ................................................................................................................................................. 70 Wheel Uprights ................................................................................................................................... 70 Upright Suspension Tabs ..................................................................................................................... 71 Spindles ............................................................................................................................................... 71 3 Hubs .................................................................................................................................................... 72 Chapter 6: Design Verification .................................................................................................................... 73 Weight Results ........................................................................................................................................ 74 Dynamic Test Plan and Equipment ......................................................................................................... 75 Strain Gages ........................................................................................................................................ 77 Transducer Calibration ........................................................................................................................ 78 Accelerometer ..................................................................................................................................... 79 DAQ ..................................................................................................................................................... 80 Initial Installation Testing ....................................................................................................................... 82 Axle Stubs ............................................................................................................................................ 82 Upright Thrust Bearing ........................................................................................................................ 84 Dynamic Testing Results ........................................................................................................................