DESIGN, ANALYSIS AND EXPERIMENTAL VERIFICATION OF TUBULAR SPACEFRAME CHASSIS FOR FSAE APPLICATION LIEW ZHEN HUI (B.Eng. (Hons.), NUS) A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF ENGINEERING DEPARTMENT OF MECHANICAL ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE 2012 Summary This project investigates various subjects of chassis with specific emphasis on FSAE application. CAE tools such as SolidWorks CAD and SolidWorks Simulation are utilized for the project. The design and analysis of the chassis is conducted with a parametric approach, which is performed in a systematic and systemic manner. Every progression of design is assessed and interpreted in detail in the thesis. Data of accelerations, which the chassis experiences during the operation of the race car, is also collected. Accelerometers are utilized for such task. Data acquired is interpreted and is related back to assumptions used in the design analysis. Stressed skin construction for the chassis is also researched and presented in the thesis, with physical tests carried out to compare the performance of stressed skin frame, “spaceframe” frame and bare frame. The knowledge gained from these tasks is documented in this thesis and to be passed to NUS FSAE race team upon completion so as to aid the development of the future race car. I Acknowledgement The author wishes to take this opportunity to express sincere gratitude to following individuals for the assistance, enabling the author to successfully accomplish the project: • Prof Seah Kar Heng • Prof Tay Tong Earn • Mr Andre Oh Yide • Mr Lim Hong Wee • Mr Goh Kim Hoo • Team NUS FSAE 2011 • Team NUS FSAE 2012 • Team NUS ECO Car 2012 II Table of Content SUMMARY ............................................................................................................................................... I ACKNOWLEDGEMENT ..................................................................................................................... II TABLE OF CONTENT ........................................................................................................................ III LIST OF TABLES ................................................................................................................................. VI LIST OF FIGURES ................................................................................................................................. X LIST OF CHARTS ............................................................................................................................... XX LIST OF GRAPHS ............................................................................................................................ XXV LIST OF EQUATIONS ................................................................................................................... XXXI LIST OF SYMBOLS ...................................................................................................................... XXXII 1. PROLOGUE ................................................................................................................................... 1 1.1. COMPETITION BACKGROUND .................................................................................................. 1 1.2. PROJECT BACKGROUND .......................................................................................................... 1 1.3. PROJECT OBJECTIVE ................................................................................................................ 2 1.4. PROJECT SCOPE ....................................................................................................................... 2 2. CHASSIS OF FSAE RACE CAR ................................................................................................. 5 2.1. FUNCTION OF CHASSIS ............................................................................................................ 5 2.2. ATTRIBUTES OF CHASSIS ......................................................................................................... 5 2.3. TYPE OF CHASSIS .................................................................................................................. 10 2.4. LOAD CASES OF CHASSIS ...................................................................................................... 17 3. DESIGN & ANALYSIS OF CHASSIS ...................................................................................... 22 3.1. TYPE OF CHASSIS CONSTRUCTION ........................................................................................ 22 3.2. TYPE OF MATERIAL ............................................................................................................... 22 3.3. DESIGN REQUIREMENTS ........................................................................................................ 22 3.4. COMPUTER AIDED ENGINEERING (CAE) TOOL ..................................................................... 24 3.5. DESIGN METHODOLOGY ....................................................................................................... 28 III 3.6. DESIGN & ANALYSIS OF CHASSIS ......................................................................................... 54 3.7. ESTIMATION OF DISCREPANCY & PREDICTION OF STRUCTURAL TORSIONAL STIFFNESS OF ENHANCED CONCEIVED CHASSIS ...................................................................................................... 154 3.8. DISCUSSION & RECOMMENDATION ..................................................................................... 160 4. DATA ACQUISITION ON OPERATION LOAD OF CHASSIS ......................................... 162 4.1. OBJECTIVE OF DATA ACQUISITION ..................................................................................... 162 4.2. OUTLINE AND PREPARATION OF TEST RUN FOR DATA ACQUISITION .................................. 163 4.3. PRESENTATION & INTERPRETATION OF DATA ..................................................................... 165 4.4. DISCUSSION & RECOMMENDATION ..................................................................................... 178 5. RESEARCH ON STRESSED SKIN CONSTRUCTION FOR CHASSIS ............................ 180 5.1. STRESSED SKIN PRINCIPLE .................................................................................................. 180 5.2. PHYSICAL COMPARISON BETWEEN TUBULAR SPACEFRAME & STRESSED SKIN CONSTRUCTION ................................................................................................................................. 183 5.3. INTERPRETATION OF DATA & PRESENTATION OF RESULT ................................................... 192 5.4. DISCUSSION & RECOMMENDATION ..................................................................................... 207 6. CONCLUSION .......................................................................................................................... 209 REFERENCE ...................................................................................................................................... 210 APPENDICES 1 - DESIGN & ANALYSIS OF CHASSIS – SHAPE OF CHASSIS ..................... 212 APPENDICES 2 - DESIGN & ANALYSIS OF CHASSIS – ORIENTATION OF BRACE ........ 230 APPENDICES 3 - DESIGN & ANALYSIS OF CHASSIS – CROSS SECTION OF STRUCTURAL ELEMENT ............................................................................................................... 250 APPENDICES 4 - DESIGN & ANALYSIS OF CHASSIS – ESTIMATION OF DISCREPANCY & PREDICTION OF STRUCTURAL TORSIONAL STIFFNESS OF ENHANCED CONCEIVED CHASSIS ..................................................................................................................... 268 APPENDICES 5 - DATA ACQUISITION ON THE OPERATION LOAD OF CHASSIS – X1-6A ACCELEROMETER .......................................................................................................................... 273 IV APPENDICES 6- DATA ACQUISITION ON THE OPERATION LOAD OF CHASSIS – ACQUIRED DATA ............................................................................................................................. 288 APPENDICES 7 - RESEARCH ON STRESSED SKIN CONSTRUCTION FOR CHASSIS ...... 298 V List of Tables TABLE 1-COMPARISON OF DEFORMATION BETWEEN TRIANGULATED AND ORIGINAL PLANAR FRAME ...... 31 TABLE 2-DYNAMIC FACTORS USED FOR NUS FSAE RACE CAR ............................................................. 45 TABLE 3-WEIGHT, STRUCTURAL TORSIONAL STIFFNESS (STS) AND SPECIFIC STRUCTURAL TORSIONAL STIFFNESS OF CHASSIS 2 WITH RESPECT TO VARIATION OF LENGTH OF FOOT WELL ......................... 59 TABLE 4-WEIGHT, STRUCTURAL TORSIONAL STIFFNESS (STS) AND SPECIFIC STRUCTURAL TORSIONAL STIFFNESS OF CHASSIS 3 WITH RESPECT TO VARIATION OF HEIGHT OF FRONT BULKHEAD ............... 61 TABLE 5-WEIGHT, STRUCTURAL TORSIONAL STIFFNESS (STS) AND SPECIFIC STRUCTURAL TORSIONAL STIFFNESS OF CHASSIS 4 WITH RESPECT TO VARIATION OF WIDTH OF FRONT BULKHEAD ................ 63 TABLE 6-WEIGHT, STRUCTURAL TORSIONAL STIFFNESS (STS) AND SPECIFIC STRUCTURAL TORSIONAL STIFFNESS OF CHASSIS 5 WITH RESPECT TO VARIATION OF HEIGHT OF FRONT MIDDLE BULKHEAD .. 65 TABLE 7-WEIGHT, STRUCTURAL TORSIONAL STIFFNESS (STS) AND SPECIFIC STRUCTURAL TORSIONAL STIFFNESS OF CHASSIS 6 WITH RESPECT TO VARIATION OF HEIGHT OF FRONT ROLL HOOP ............... 69 TABLE 8-WEIGHT, STRUCTURAL TORSIONAL STIFFNESS (STS) AND SPECIFIC STRUCTURAL TORSIONAL STIFFNESS OF CHASSIS 7 WITH RESPECT TO VARIATION OF LENGTH OF DRIVER COCKPIT ................. 72 TABLE 9-WEIGHT, STRUCTURAL TORSIONAL STIFFNESS