Graduation design (paper) of

Wuhan university of technology

The suspension design of automatic driving light electric Vehicle

college： college of international education

major class： Vehicle engineering 1601

student name： Yikang Liu

instructor： Houyu Yu

Original statement of Dissertation

I solemnly declare that the paper I submit is the research results I have obtained under the guidance of my tutor. Except for the contents specially noted and quoted in the paper, this paper does not include any other individual or collective published or written works. I am fully aware that I am responsible for the legal consequences of this statement.

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28^th May, 2020

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Author's signature:

Date: 2020.5.28

Signature of Tutor:

Date: 2020.5.28

Abstract

In this paper, the front and rear suspension of automatic driving light electric vehicle are designed, and the general design methods of McPherson suspension and trailing arm suspension are introduced. In the process of component design, MATLAB is used to simplify the calculation. After the theoretical design is completed, the model of front and rear suspension are established with CATIA software, and Assembly drawing and part drawing are drawn using AutoCAD. Using the coordinates of the hardpoint to build the suspension simulation model ,and then the characteristics of suspension are simulated with ADMAS CAR software, and the curve of suspension kinematic parameters with wheel -travel is obtained. We can improve the vehicle suspension characteristics and relevant ride comfort and handling stability by the optimization of hardpoint coordinates.

The results of suspension simulation show that the designed suspension can meet the requirements of vehicle performance basically.

Key Words： McPherson Suspension; Drag -arm Suspension; CATIA;

ADMAS CAR; simulation;

catalogue

Chapter 1 Introduction 1

1.1 The significance of suspension design 1

1.1.1 The composition and function of the suspension 1

1.1.2 Classification of suspension 2

1.1.3 Purpose and significance of suspension design 3

1.2 Research status at Chinese and abroad 3

1.2.1 Semi-active suspension 3

1.2.2 Active suspension 4

Chapter 2 Suspension type selection and determination of main parameters 5

1.3 Types of suspensions 5

2.1.1 Select the front suspension type 6

2.1.2 Select the rear suspension type 7

1.4 Type of suspension component 8

1.4.1 Elastic elements 8

1.4.2 Guiding mechanism 8

1.4.3 Damper element 9

1.5 Determination of main parameters of suspension 9

1.5.1 Offset frequency of front and rear suspension 9

1.5.2 Calculation of static deflection of suspension 10

1.5.3 Calculation of dynamic deflection of suspension 11

Chapter 3 Design of McPherson Suspension 13

1.6 Elastic element design 13

1.6.1 Elasticity of suspension 13

3.1.2 Spiral spring design 13

1.6.3 Spring check 18

1.6.4 3D model of spiral Spring 20

1.7 Damper design 21

3.2.1 Structure and working principle of double cylinder hydraulic damper 21

3.2.2 Damping characteristics 22

3.2.3 Determine the relative damping coefficient ψ 24

3.2.4 Determine the damping coefficient δ 24

3.2.5 Type of damper 27

3.2.6 Size of damper 28

3.2.7 3D Model of damper 29

3.3 Guiding mechanism design 30

3.3.1 Layout of the axis of McPherson suspension 31

3.3.2 Lower control arm 33

Chapter 4 Design of rear suspension 37

1.8 Torsion bar spring design 37

4.1.1 Shape and end structure selection 37

4.1.2 Material selection 39

4.1.3 Determine torsion bar diameter 39

4.1.4 Torsion bar strength checking 40

4.1.5 Design of torsion bar end 40

4.1.6 3D model of Torsion bar spring 42

4.2 Design of rear suspension damper 43

4.2.1 Determine the relative damping coefficient ψ 43

4.2.2 Determine the damping coefficient δ 44

4.2.3 the maximum unloading force 44

4.2.4 Diameter of working cylinder 44

4.2.5 Select the working stroke 45

Chapter 5 Calculation of suspension roll stiffness 47

5.1 Height of roll center 47

5.2 roll axis 48

5.3 roll stiffness 49

5.4Design of stabilizer bar 52

Chapter 6 ADMAS CAR Simulation of McPherson Suspension 54

6.1 Suspension Model 54

6.2 Suspension Simulation Analysis 55

6.2.1 Simulation results 56

6.2.2 Model modification and optimization 59