© Copyrighted by Tittu Paul May, 2019 All Rights Reserved DESIGN OF CHASSIS, IMPACT ATTENUATOR, SUSPENSION AND AERODYNAMIC SYSTEMS OF A FORMULA SAE CAR A Thesis Presented to the Faculty of the Department of Engineering Technology University of Houston In Partial Fulfillment of the Requirements for the Degree Master of Science in Engineering Technology by Tittu Paul May, 2019 DESIGN OF CHASSIS, IMPACT ATTENUATOR, SUSPENSION AND AERODYNAMIC SYSTEMS OF A FORMULA SAE CAR _______________________ Tittu Paul Approved: ______________________ Chair of the Committee Anthony P. Ambler, Dean, College of Technology ______________________ Co-chair of the Committee Burak Basaran, Instructional Assistant Professor, Engineering Technology Committee Members: _______________________ Navdeep Singh, Instructional Assistant Professor, Engineering Technology _______________________ Kamran Alba, Assistant Professor, Engineering Technology _______________________ _______________________ George Zouridakis, Associate Dean of Wajiha Shireen, Chair, Research, College of Technology Engineering Technology ACKNOWLEDGEMENTS I would like to express my sincere gratitude to many people for their generous contributions and encouragement throughout the works involved in my thesis. First and foremost, I would like to express my great appreciation to my thesis advisor Dr. Burak Basaran for his technical support, patient guidance and advices. He was always there to motivate me whenever I was struggling with the progress and helped me with the directions. This work would not have been possible without his invaluable supports. I would also like to thank the members of my thesis committee, Dr. Navdeep Singh and Dr. Kamran Alba for their valuable comments and guidance for helping me to finish my works. Working with Dr. Navdeep Singh as an Instructional Assistant for four semesters was a great learning platform and has immensely helped me with the FEA methods required for my thesis work. I would like to thank my parents and my sister who are always my motivation and strength and for the sacrifices they made throughout my life. They were always there with a smile during all the struggles I had in life and taught me how to overcome them together. I would also like to thank my valuable friends for being there for me whenever I needed them. v DESIGN OF CHASSIS, IMPACT ATTENUATOR, SUSPENSION AND AERODYNAMIC SYSTEMS OF A FORMULA SAE CAR An Abstract of a Thesis Presented to the Faculty of the Department of Engineering Technology University of Houston In Partial Fulfillment of the Requirements for the Degree Master of Science in Engineering Technology by Tittu Paul May, 2019 vi ABSTRACT Designing the first car for a Formula SAE team can be very challenging and confusing due to close interconnection between the design process of different subsystems. Once the working car is built, it is comparatively easy for the teams to build next year cars by testing and improving the already existing model. This thesis documents an attempt made to design the chassis, impact attenuator, aerodynamics and suspension systems of the first UH College of Technology Formula SAE car. A systematic design methodology was adopted to tackle the challenge of having many unavailable inputs while designing each subsystem. The effectiveness of various parameters selected during designing each subsystem where validated through testing. Chassis was designed according to the FSAE competition rules with the aim of achieving a specific target torsional stiffness. A standard impact attenuator was analyzed using SOLIDWORKS drop test simulation with different impact absorbing materials for its crashworthiness. An optimized double wishbone suspension was designed at front and rear which was found to be the best option available for Formula SAE cars. For the aerodynamic system, optimized multi element wings were designed as front, rear and side devices using ANSYS FLUENT. An undertray diffuser design was compared to the downforce generation capabilities of a side wing, both within the available space limits, and the side wing was found to be generating more downforce. Loads acting on suspension links were found out by calculating the load transfer expected to happen while cornering, braking and accelerating. Finally, FEA was conducted on the suspension links to determine the minimum tube size requirements for the components. vii Table of Contents ACKNOWLEDGEMENTS ..........................................................................................................v ABSTRACT ................................................................................................................................. vii LIST OF TABLES ...................................................................................................................... xii LIST OF FIGURES ................................................................................................................... xiii NOMENCLATURE ................................................................................................................... xvi CHAPTER 1: Introduction ..........................................................................................................1 1.1 FSAE Competition Overview ....................................................................................... 1 1.1.1 About the Competition ................................................................................... 1 1.1.2 General Design Objectives ............................................................................ 2 1.1.3 Vehicle Evaluation Process............................................................................ 3 1.2 FSAE Car Component Systems ................................................................................... 7 1.2.1 Chassis Subsystem ........................................................................................ 7 1.2.2 Suspension Subsystem .................................................................................. 8 1.2.3 Aerodynamic Subsystem .............................................................................. 8 1.2.4 Powertrain Subsystem ................................................................................... 9 1.2.5 Electrical Subsystem ................................................................................... 10 1.3 Design Process Overview .......................................................................................... 11 1.3.1 Thesis Objectives ........................................................................................ 11 1.3.2 Design Methodology ................................................................................... 12 viii CHAPTER 2: Design of Initial parameters ..............................................................................17 2.1 Study on Features of Best Performing FSAE Cars .................................................... 17 2.2 Selection of Target Vehicle Parameters ..................................................................... 19 2.2.1 Tire and Wheel Selection ............................................................................. 19 2.2.2 Wheel base and Track width ........................................................................ 21 2.2.3 Suspension Type Selection .......................................................................... 23 2.2.4 Chassis Type Selection ................................................................................ 26 CHAPTER 3: Component Design ..............................................................................................28 3.1 Initial Chassis Wireframe Design .............................................................................. 28 3.1.1 Chassis Design Rules ................................................................................... 28 3.1.2 Initial Wireframe Design ............................................................................. 31 3.2 Design of Suspension Geometry ................................................................................ 32 3.2.1 Selection of Suspension Parameters ........................................................... 32 3.2.1.1 Front View Swing Arm Length .................................................... 32 3.2.1.2 King Pin Inclination and Scrub Radius ......................................... 33 3.2.1.3 Roll center Height ......................................................................... 34 3.2.2 Front and Rear Suspension Geometry Design ............................................. 35 3.3 Optimized Chassis Design and Testing ...................................................................... 38 3.3.1 Final chassis design process......................................................................... 38 ix 3.3.2 Material Selection ....................................................................................... 40 3.3.3 Chassis Finite Element Analysis ................................................................. 41 3.4 Impact Attenuator Design ........................................................................................... 47 3.4.1 Impact Attenuator Rules .............................................................................. 47 3.4.2 Impact Attenuator Modelling ...................................................................... 48 3.4.3 Material selection and Testing .................................................................... 49 3.5 Design of Aerodynamic Devices ...............................................................................