Graduation Design of Wuhan University of Technology

Design of a Monocoque Chassis and the Arrangement for a Formula SAE Racing Car

School: School of International Education

Specialty amp; Class: Vehicle gj1304

Student name: Xu Xiaocheng

Tutor: Pei Xiaofei

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Abstract

The monocoque chassis designed in this report is based on the race car of WUTE Racing in 2017 season, following the Formula Student Rules. This report starts from the research on CFRP sandwich panel structure. With the method of combining mechanical tests with finite element simulation, an analyzing method is put forward to verify the reliability of sandwich panels. In this way, this report designs several relatively ideal layups, which would be used for final design of monocoque chassis. In addition, the report uses CAD software to create a 3-D model of monocoque chassis and analyzes its aerodynamic characteristics and arrangement. In addition, the torsional rigidity, strength and inherent frequency of the monocoque chassis are simulated and checked by the finite element software in order to verify the reliability of the design. Finally, the autoclave molding process, molding scheme and molding procedure are introduced.

Key Words: monocoque chassis; CFRP sandwich panel; finite element analysis

Contents

1. Introduction 1

1.1 FSEC Competition 1

1.2 Formula Student Rules 1

1.3 Design Flow 2

2. CFRP Sandwich Panel 4

2.1 Sandwich Panel Theory 4

2.1.1 Introduction of Sandwich Panel 4

2.1.2 Mechanical Characters of CFRP Sandwich Panel 5

2.1.3 Failure Modes 6

2.2 Mechanical Testing 7

2.2.1 Relevant Rules 7

2.2.2 Raw Materials 8

2.2.3 Preliminary Design of Layups 9

2.2.4 Autoclave Process 10

2.2.5 Test Device and Setting 11

2.2.6 Result Analysis 12

2.3 Finite Element Simulation of CFRP Sandwich Panel 13

2.3.1 Preprocessing 13

2.3.2 Fitting of Simulation and Test Results 16

2.4 Optimization of Layups 18

2.5 Exploration of Influence Factors 20

2.5.1 The Influence of the Thickness of Skin 21

2.5.2 The Influence of the Thickness of Core 22

2.5.3 The Influence of the Core Material 22

2.5.4 The Influence of the Symmetry of Layups 23

2.6 Chapter Conclusion 23

3. Design and Analysis 24

3.1 Shape and 3D-Modeling 24

3.2 External Flow Field Simulation and Comparison Analysis 24

3.2.1 Pre-Processing 25

3.2.2 Result Analysis 25

3.3 Optimization of Arrangement 26

3.4 Structural Simulation and Checking 28

3.4.1 Pre-Processing 28

3.4.2 Calculation of Torsional Rigidity 28

3.4.3 Failure Checking of Monocoque Chassis 29

3.4.4 Modal Analysis 36

3.5 Chapter Conclusion 38

4. Molding Process 39

4.1 Autoclave Molding 39

4.2 Mold of Monocoque Chassis 39

4.3 Molding Procedure 40

4.4 Chapter Conclusion 40

5. Conclusion 41

References 42

Appendix A. Final Layups and Cores Scheme 44

Acknowledgement 46

Chapter 1. Introduction

1.1 FSEC Competition

Formula Student Electric China is a part of Formula SAE (Formula Society of Automotive Engineers) Series, namely FSEC for abbreviation. Formula SAE Series is a collegiate racing series organized by Society of Automotive Engineers of countries in different continents. Teams formed by university students are required to design and build a single-seat race car with good performance on accelerating, braking and handing in one year, following the Formula Student Rules. Teams compete in eight events (three statics events and five dynamic events), each worth a certain amount of points, listed in Table 1.1.

Table 1.1 Formula SAE Event Points Summary

Teams would finally be ranked according to the points they get.

1.2 Formula Student Rules