GIRDER MOUNTAIN BIKE FORK A thesis submitted to the Faculty of the Mechanical Engineering Technology Program of the University of Cincinnati in partial fulfillment of the requirements for the degree of Bachelor of Science in Mechanical Engineering Technology at the College of Engineering & Applied Science by RYAN LINDENBERGER Bachelor of Science University of Cincinnati May 2012 Faculty Advisor: Amir Salehpour ACKNOWLEDGEMENTS I would like to personally thank Professor Amir Salehpour for continually pushing me during the design phase of this project. He helped me see problems that I might encounter with a given design or loading condition. This was especially helpful in establishing a realistic worst case loading condition. My gratitude goes out to Nicholas Plataniotis. Without his machining and welding knowledge this project would have been significantly more difficult. I would also like to thank all of my friends and family that helped with the manufacturing and testing of the fork. Without their support none of this would have been possible. ii TABLE OF CONTENTS GIRDER MOUNTAIN BIKE FORK ....................................................................................... 1 ACKNOWLEDGEMENTS ...................................................................................................... II TABLE OF CONTENTS ........................................................................................................ III LIST OF FIGURES ................................................................................................................. V LIST OF TABLES ................................................................................................................... V ABSTRACT ............................................................................................................................ VI PROBLEM DEFINITION AND BACKGROUND ................................................................. 1 RIGID FORK DESIGN ............................................................................................................ 2 GENERAL TELESCOPING FORK DESIGN ......................................................................... 3 GENERAL GIRDER FORK DESIGN ..................................................................................... 5 RESEARCH .............................................................................................................................. 8 EXISTING GIRDER MOUNTAIN BIKE FORKS ........................................................................................................ 8 CUSTOMER FEADBACK .................................................................................................... 10 INTERVIEW ....................................................................................................................................................... 10 CUSTOMER SURVEY ......................................................................................................................................... 10 HOUSE OF QUALITY .......................................................................................................................................... 11 PRODUCT OBJECTIVES ..................................................................................................... 14 DESIGN ALTERNATIVES AND SELECTION .................................................................. 16 DESIGN 1 .......................................................................................................................................................... 16 DESIGN 2 .......................................................................................................................................................... 17 DRAWINGS ........................................................................................................................... 20 LOADING CONDITIONS ..................................................................................................... 36 DESIGN ANALYSIS ............................................................................................................. 38 HAND CALCULATIONS ...................................................................................................................................... 38 COSMOS SIMULATIONS .................................................................................................................................. 40 FACTORS OF SAFETY OF CONCERN .............................................................................. 44 COMPONENT SELECTION ................................................................................................. 47 BILL OF MATERIALS .......................................................................................................... 48 PROTOTYPE BUDGET ........................................................................................................ 49 SCHEDULE ............................................................................................................................ 51 MANUFACTURING ............................................................................................................. 52 MACHINING ...................................................................................................................................................... 52 WELDING ......................................................................................................................................................... 55 PLASMA CUTTING ............................................................................................................................................ 57 iii DESIGN MODIFICATIONS .................................................................................................................................. 59 HIGH VOLUME PRODUCTION .......................................................................................... 60 TESTING ................................................................................................................................ 61 CONCLUSION ....................................................................................................................... 65 WORKS CITED ..................................................................................................................... 66 APPENDIX A - RESEARCH ................................................................................................... 1 APPENDIX B – CUSTOMER SURVEY AND RESULTS .................................................... 1 APPENDIX C – QUALITY FUNCTION DEPLOYMENT .................................................... 1 APPENDIX D – PRODUCT OBJECTIVES ............................................................................ 1 APPENDIX E – SCHEDULE .................................................................................................. 1 APPENDIX F – PROTOTYPE BUDGET ............................................................................... 1 iv LIST OF FIGURES Figure 1: Common Mountain Bike Forks ................................................................................. 1 Figure 2: Rigid Fork.................................................................................................................. 2 Figure 3: Telescopic Fork ......................................................................................................... 3 Figure 4: Telescopic Fork Cut Away ........................................................................................ 4 Figure 5: Typical Girder Fork Layout ...................................................................................... 5 Figure 6: Steering Geometry ..................................................................................................... 6 Figure 7: Yamaha R1 with Custom Girder Fork ...................................................................... 7 Figure 8: Girvin Fork ................................................................................................................ 9 Figure 9: Design 1 ................................................................................................................... 16 Figure 10: Design 2 ................................................................................................................. 17 Figure 11: FOURBAR Program ............................................................................................. 18 Figure 12: Design 2 Suspension Travel .................................................................................. 19 Figure 13: Loading Conditions ............................................................................................... 37 Figure 14: Lower Link Stress ................................................................................................. 40 Figure 15: Lower Link Displacement ..................................................................................... 41 Figure 16: Lower Block Stress ............................................................................................... 41 Figure 17: Lower Block Displacement ................................................................................... 42 Figure 18: Upper Block Stress ................................................................................................ 42 Figure 19: Upper Block Displacement ................................................................................... 43 Figure 20: Fork Sub-Assembly Stress & Displacement ......................................................... 44