Design and 3D Printing of Down-scaled Passenger Vehicle Chassis Bachelor’s Thesis in Mechanical Engineering Anton Öhammar, Jacob Grundén, Jon Jaleby, Kristofer Arvidsson, Oskar Hellsten, Simon Medbo Department of Applied Mechanics CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden 2017 2 BACHELOR’S THESIS IN MECHANICAL ENGINEERING Design and 3D Printing of Down-scaled Passenger Vehicle Chassis Anton Öhammar, Jacob Grundén, Jon Jaleby, Kristofer Arvidsson, Oskar Hellsten, Simon Medbo Department of Applied Mechanics Division of Vehicle Engineering and Autonomous Systems Vehicle Dynamics Group CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden 2017 Design and 3D Printing of Down-scaled Passenger Vehicle Chassis Anton Öhammar, Jacob Grundén, Jon Jaleby, Kristofer Arvidsson, Oskar Hellsten, Simon Medbo © Anton Öhammar, Jacob Grundén, Jon Jaleby, Kristofer Arvidsson, Oskar Hellsten, Simon Medbo, 2017-05-12 Bachelor’s Thesis 2017:04 ISSN 1654-4676 Department of Applied Mechanics Division of Vehicle Engineering and Autonomous Systems Vehicle Dynamics Group Chalmers University of Technology SE-412 96 Göteborg Sweden Telephone: + 46 (0)31-772 1000 Examiner: Bengt Jacobson [email protected] Supervisor: Ingemar Johansson [email protected] Department of Applied Mechanics Göteborg, Sweden 2017-05-12 4 Design and 3D Printing of Down-scaled Passenger Vehicle Chassis Bachelor’s thesis in Mechanical Engineering Anton Öhammar, Jacob Grundén, Jon Jaleby, Kristofer Arvidsson, Oskar Hellsten, Simon Medbo Department of Applied Mechanics Division of Vehicle Engineering and Autonomous Systems Vehicle Dynamics Group Chalmers University of Technology Abstract To close the gap between the automotive industry and newly graduated engineers the graduates need to have a better understanding for how their design affects the end result. This thesis focuses on producing 3D printed suspension scale models with correct kinematics to help students better understand how different types of suspensions behave. The suspension types chosen for the models are MacPherson and double wishbone for the front suspensions and trailing arm multi link suspension and a live axle for the rear. These models were designed in Catia V5 and then 3D printed in a scale of 1:5 and assembled together with some off-the-shelf components such as coilover dampers and ball joints. The models for the MacPherson and the trailing arm are based on Chalmers suspension setups while the live axle is based on modified values of the trailing arm. The double wishbone however is primarily based on given requirements and guidelines from the Chalmers suspension setup. The two front suspensions feature functioning steering and the MacPherson one also has a differential to illustrate the function of having a propulsion system. These suspensions are mounted on two vehicle chassis where the front suspensions can be swapped so all the combinations can be shown. The curves for camber gain and bump steer are plotted for the MacPherson and double wishbone suspensions. The 3D printed models have similar kinematics to the original models. Because of the limited accuracy of 3D printing there is some play in the suspension components reducing the similarity between the curves and the real behavior when manipulating the suspensions by hand. Keywords: vehicle suspension, 3D printing, kinematics, chassis, vehicle dynamics Acknowledgements We would like to say a special thanks to our supervisor Ingemar Johansson for his outstanding work and help during this project. Without his expert knowledge and will to help we would not have come as far nor have the understanding that we today have. Thank you Ingemar II Preface This thesis was done as a bachelor thesis at the Mechanical engineering programme of Chalmers University of Technology, Gothenburg. The work was carried out between January and May 2017. Gothenburg May 2017 Anton Öhammar, Jacob Grundén, Jon Jaleby, Kristofer Arvidsson, Oskar Hellsten, Simon Medbo Abbreviations CAD - Computer Aided Design 3D - 3 Dimensional NVH - Noise, Vibrations and Harshness PLA - Polylactide CC - Centre-Centre RC - Radio Controlled IV Contents Abstract ............................................................................................................................................... I Acknowledgements ...................................................................................................................... II Preface ............................................................................................................................................... III Abbreviations ................................................................................................................................. IV Contents .............................................................................................................................................. V 1 Chapter One - Introduction ................................................................................................... 1 1.1 Background .......................................................................................................................... 1 1.2 Purpose With the Project ............................................................................................... 1 1.3 Envisioned Solution ......................................................................................................... 1 1.4 Deliverables ......................................................................................................................... 1 1.5 Prerequisites ....................................................................................................................... 1 1.6 Limitations ........................................................................................................................... 2 1.7 Method ................................................................................................................................... 2 1.8 Participants and Function in the Project ................................................................. 2 2 Chapter Two – Background Theory .................................................................................. 3 2.1 Introduction to Vehicle Technology – Wheel Suspension Engineering ..... 3 2.2 Wheel Suspension Parts ................................................................................................. 3 2.2.1 Spring............................................................................................................................. 3 2.2.2 Shock Absorber ......................................................................................................... 3 2.2.3 Coilover Damper ....................................................................................................... 3 2.2.4 Strut ................................................................................................................................ 3 2.2.5 Anti-roll Bar ................................................................................................................ 3 2.2.6 Upright .......................................................................................................................... 4 2.2.7 Control Arm and Link ............................................................................................. 4 2.2.8 Bushing ......................................................................................................................... 4 2.2.9 Ball Joint ....................................................................................................................... 4 2.2.10 Subframe ...................................................................................................................... 4 2.3 Terms and Definitions – Wheel Suspension Engineering ................................ 4 2.3.1 Coordinate System and Forces ........................................................................... 4 2.3.2 Hardpoints ................................................................................................................... 5 2.3.3 Body Roll ...................................................................................................................... 5 2.3.4 Roll Centre ................................................................................................................... 5 2.3.5 Dive and Squat ........................................................................................................... 5 2.3.6 Jounce and Rebound ............................................................................................... 5 2.3.7 Bump Stop ................................................................................................................... 5 2.3.8 Contact Patch .............................................................................................................. 6 2.3.9 Ground Clearance ..................................................................................................... 6 2.3.10 Bump Steer .................................................................................................................. 6 2.3.11 Camber .......................................................................................................................... 6 2.3.12 Caster ............................................................................................................................. 6 2.3.13 Toe .................................................................................................................................