Wuhan University of Technology Undergraduate Graduation Design (Thesis)

Design of Shanghai Volkswagen LaVida sedan rear torsion beam type independent suspension

School: Wuhan University of Technology

Specialty amp; Class: Automotive Engineering gj1603

Name: Wang Zhiping

Tutor: Fang Zhigang

Statement of Degree Thesis originality

I solemnly declare：The thesis submitted is the research result independently obtained by myself under the guidance of my tutor. Except for the contents specifically quoted in this thesis, this thesis does not include any other works that have been published or written by individuals or groups. I fully understand that the legal consequences of this statement are borne by me.

Author’s Signature： Wang Zhiping

Date: 2020.5.30

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Author’s Signature：Wang Zhiping Date: 2020.5.30

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Abstract

For most small and medium-sized family cars, the rear suspension basically uses a torsion beam non-independent suspension. As a non-independent suspension, the torsion beam suspension has obvious advantages, but the shortcomings also exist. Therefore, the characteristics of the torsion beam suspension are directly related to the performance of the vehicle. In order to understand the characteristics of this suspension, this article has designed the structure of the torsion beam suspension for a certain Volkswagen LaVida model, and has used CATIA software for 3D modeling. Using ANSYS finite element analysis software, the stress analysis of the damping spring is carried out in this paper. Through the ADAMS / CAR simulation software, a model was established to understand the basic characteristics of the torsion beam suspension and the changes in wheel positioning parameters. This article provides some ideas for the design and verification of damping springs and provides a reference for the understanding of the basic parameters of the suspension.

Key words: torsion beam suspension; dynamic simulation; static analysis; structural design

Contents

Abstract III

Chapter 1 Introduction 1

1.1 Research background and significance 1

1.2 Research status at home and abroad 2

1.3 Research content 2

Chapter 2 Overview of Automotive Suspension 4

2.1 Suspension concept 4

2.2 Basic composition of suspension 4

2.3 Functions of suspension 5

2.4 Design requirements of suspension 5

Chapter 3 Initial Data 7

Chapter 4 Determination of main parameters of suspension 8

4.1 Static deflection of suspension 8

4.2 Dynamic deflection of suspension 10

4.3 Calculation of suspension stiffness 10

4.4 Main analysis parameters of suspension 11

4.4.1 Wheel camber 11

4.4.2 Toe-in 11

4.4.3 Kingpin angle 12

4.4.4 Kingpin inclination 12

4.4.5 Height of roll center 12

4.4.6 Roll camber coefficient 13

Chapter 5 Design of Main Parts of Suspension 14

5.1 Design of spiral spring 14

5.1.1 Material selection of spiral spring 14

5.1.2 stiffness of spiral spring 15

5.1.3 Calculation of spring parameters 15

5.1.4 Spring check 19

5.2 Design of shock absorber 21

5.2.1 Introduction to shock absorbers 21

5.2.1 Introduction to shock absorbers 21

5.2.2 Shock absorber type selection 21

5.2.3 Determination of relative damping coefficient 23

5.2.4 Determination of damping coefficient K of shock absorber 25

5.2.5 Determination of the maximum unloading force of shock absorber 26

5.2.6 Determination of diameter D of working cylinder of shock absorber 27

Chapter 6 Suspension modeling 29

6.1 Introduction to modeling software CATIA 29

6.2 Three-dimensional modeling of main parts 29

6.2.1 Three-dimensional modeling of torsion beam and trailing arm 29

6.2.2 Three-dimensional modeling of shock absorber 30

6.2.3 Three-dimensional modeling of springs 30

6.2.4 Three-dimensional modeling of other components 31

6.2.5 Suspension assembly 32

Chapter 7 Suspension Simulation Analysis 33

7.1 Static analysis of helical spring 33

7.1.1 Theoretical force analysis of spring 33

7.1.2 Static stress simulation analysis 34

7.2 Dynamics simulation analysis of suspension based on Adams 35

7.2.1 Create a suspension model 35

7.2.2 Parallel wheel travel simulation 36

Chapter 8 Conclusion 40

References 41

Express thanks 43

Chapter 1 Introduction

1.1 Research background and significance

With the rapid development of human social science and technology and people's pursuit and longing for high-quality life, higher requirements are placed on the performance of vehicles, especially to have good handling stability and driving smoothness to meet the demand of market and consumer for the current development of the automotive industry.

Suspension is the general term for all force-transmitting connection devices between the axle (or wheel) and the frame (or load-bearing body). The main function of the suspension system is to mitigate the impact of the road on the vehicle, attenuate the vibration between the body and the wheel, transmit the force between the wheel and the road, control the movement posture of the wheel and the body, and ensure the normal driving of the car. According to the independent characteristics of left and right wheel movement when the wheels are subjected to road vibration, the suspension system is generally divided into two categories: independent suspension and non-independent suspension. The suspension system is an important part of the chassis system of an automobile, and has an important impact on the driving safety, comfort, and sports performance of the automobile ^[6].