Washington University in St. Louis Washington University Open Scholarship Mechanical Engineering and Materials Science Independent Study Mechanical Engineering & Materials Science 1-11-2019 Design of the WUFR-19 FSAE Suspension Alex Levy Washington University in St. Louis James J. Potter Washington University in St. Louis Follow this and additional works at: https://openscholarship.wustl.edu/mems500 Recommended Citation Levy, Alex and Potter, James J., "Design of the WUFR-19 FSAE Suspension" (2019). Mechanical Engineering and Materials Science Independent Study. 83. https://openscholarship.wustl.edu/mems500/83 This Final Report is brought to you for free and open access by the Mechanical Engineering & Materials Science at Washington University Open Scholarship. It has been accepted for inclusion in Mechanical Engineering and Materials Science Independent Study by an authorized administrator of Washington University Open Scholarship. For more information, please contact [email protected]. Fall 2018 MEMS 400 Independent Study Project Design of the WUFR-19 FSAE Suspension Alex Levy – B.S. Mechanical Engineering ’20 Advisor: Dr. James Jackson Potter – Faculty Dept. of Mechanical Engineering Contents Abstract ..................................................................................................................................................................... 4 1 Wash U Racing .................................................................................................................................................. 4 1.1 Role of a Suspension ...................................................................................................................................... 4 1.2 WUFR-19 Suspension ..................................................................................................................................... 5 2 The FSAE Challenge and Constraints ................................................................................................................. 5 2.1 The Events ..................................................................................................................................................... 6 2.2 Team Constraints .......................................................................................................................................... 9 2.3 System Constraints ................................................................................................................................... 9 3 Resources and Software for Design ................................................................................................................ 10 3.1 Research Library .......................................................................................................................................... 10 3.2 Software Catalog ......................................................................................................................................... 11 4 Car and Sensor Data ........................................................................................................................................ 12 4.1 Collected Sensor Data ................................................................................................................................. 12 4.2 Basic Car Weight Parameters – BFR18 ........................................................................................................ 13 5 Tires and Tire Data .......................................................................................................................................... 13 5.1 Tire Selection ............................................................................................................................................... 13 5.2 Tire Data .............................................................................................................................................. 14 5.3 Application of Tire Data ...................................................................................................................... 19 6 Suspension Geometry ..................................................................................................................................... 23 6.1 Front View Geometry .................................................................................................................................. 23 6.2 Additional Points and Steering Geometry .................................................................................................. 33 7 OptimumKinematics Results ........................................................................................................................... 34 Going Forward ........................................................................................................................................................ 42 Appendix A: Additional Technical Information ....................................................................................................... 42 A.1: Spring Rates ..................................................................................................................................................... 42 References .............................................................................................................................................................. 43 1 List of Figures Figure 1: A Top View of a Double Wishbone Suspension with Toe Link [2, p. 643] ................................ 5 Figure 2: WashU Racing's BFR18 Double A-Arm Suspension .......................................................................... 5 Figure 3: The Skid Pad Schematic as Provided in the 2019 Rules [3, p. 123] ............................................. 8 Figure 4: The Autocross Schematic as Provided in the 2019 Rules [5] ........................................................ 8 Figure 5: The 2018 Endurance Track from FSAE Michigan [6] ....................................................................... 9 Figure 6: The Cardinal Planes for SU-93001-BA in SolidWorks .................................................................... 11 Figure 7: As an example, the 2019 Front Suspension Modeled in Optimum Kinematics .................... 12 Figure 8: The Definition of a Tire Slip Angle [1, p. 14] ....................................................................................... 15 Figure 9: The De-Identified Graph of Lateral Force Against Slip Angle for the R25B 18.0x7.5-10 [23] ................................................................................................................................................................................................. 16 Figure 10: The De-Identified Graph of Instantaneous Cornering Stiffness Against Lateral Force for the R25B 18.0x7.5-10 [23] ........................................................................................................................................... 17 Figure 11: The De-Identified Graph of Instantaneous Cornering Stiffness Against Slip Angle for the R25B 18.0x7.5-10 [23] ................................................................................................................................................... 17 Figure 12: Aligning Torque on the Footprint of a Tire [2, p. 70] ................................................................... 18 Figure 13: The De-Identified Graph of Aligning Torque Against Slip Angle for the R25B 18.0x7.5-10 [23] ........................................................................................................................................................................................ 19 Figure 14: The Bicycle Model [2, p. 127] ................................................................................................................. 20 Figure 15: The Steer Camber Curve for the 1.2g Left Turn .............................................................................. 21 Figure 16: The Front and Rear Wheel Center Planes Set a Distance Apart by the Wheelbase .......... 23 Figure 17: The Pitch Motion Loaded in to OptimumKinematics ................................................................... 24 Figure 18: SU-93001-BA with Front and Rear Track Planes on Both Sides of the Car ......................... 28 Figure 19: A Roll Center Height on a Suspension Geometry [2, p. 614]...................................................... 29 Figure 20: The Front View Swing Arm [2, p. 628] ............................................................................................... 30 Figure 21: The Heave Camber Change Rate ........................................................................................................... 31 Figure 22: The Roll Camber Change Rate ............................................................................................................... 31 Figure 23: The Final Front-Front View Geometry ............................................................................................... 32 Figure 24: The Final Rear-Front View Geometry................................................................................................. 32 Figure 25: Important Placement of Components within the Wheel ............................................................. 33 Figure 26: The Steer Camber Curve .......................................................................................................................... 34 Figure 27: The Heave Motion Modeled in OptimumKinematics ...................................................................