摘 要

　　车身是轿车的关键总成之一,发动机及各种附件都安装在车身上,它的构造决定了整车的一系列性能，比如行驶平顺性，直接关系到乘客乘坐的舒适性。对白车身进行模态分析可以得出车身的各阶固有频率，我们就可以改进车身结构，从而减小汽车行驶时车身的振动。本文基于有限元和模态理论，运用hyperworks等软件对某轿车白车身进行了模态分析，并对车身重要连接点的动刚度进行了分析，从而对车身结构做出优化。本文主要对以下内容进行了阐述：

1.首先讨论在有限元建模中的需要注意的问题，从而对白车身模型进行相应的简化，建立白车身有限元模型。通过将有限元模型导入到hyperworks进行模态分析，得到模态参数。然后重点分析白车身的各阶固有频率和各阶振型。

2.对动刚度理论进行了讨论，然后选择整车的某些重要连接点进行了动刚度分析。

3.最后讨论了白车身的板厚变化对于固有模态频率的影响。在同时考虑车身固有频率、整车重量和板厚实际情况等因素的前提下，对白车身板厚进行优化，经过计算机多次迭代计算后，最终找到了一个最为合适的板厚值。

4.对全文进行总结，主要阐述了本文所做研究工作得出的结论并指出了不足之处，最后对今后将要继续研究的内容进行了展望。

关键词：白车身，模态分析，动刚度分析，结构优化

Abstract

　　Body is one of the key assembly of cars, is the installation of engines and interior accessories such as the matrix, its structure determines the vehicle's performance, such as ride, directly related to the comfort of the passengers. White body modal analysis to assess not only the overall stiffness of the body structure, and guide people to optimize the body structure and response analysis. Based on the finite element method and modal analysis, use of hyperworks software for a car body modal analysis, and the analysis of an important connection point of the dynamic stiffness of the body. This article explains the following:

　　1. To begin with a guidelines of the finite element model , and white body model features simplified established body finite element model. Also studied the theory of modal analysis, adoption will be imported into the hyperworks RADIOSS finite element model for modal analysis, modal parameters were obtained. Then focuses on the analysis of BIW's natural frequencies and dynamic stiffness of some important junction.

　　2. Another aspect of the study is the body effect of plate thickness on the modal parameters. In considering body performance, vehicle weight and production costs and other elements of the premise, thick white body panels are optimized, well meet the design requirements, final size by adjusting the white body panels of thick, one finds the most suitable body panels thickness.

3. Summary of the full text, describing the research work and came to the conclusion, and prospects for further study of the content.

Key words:body-in-white,Modal analysis,Dynamic stiffness analysis,Structure Optimization

目录

第一章 目的和意义......................................................................................................6

1.1目的........................................................................................................................6

1.2意义........................................................................................................................6

1.3白车身振动特性仿真分析国内外研究现状........................................................6

1.3.1白车身振动特性仿真分析国内研究现状...................................................6

1.3.2白车身振动特性仿真分析国外研究现状...................................................8

第二章 白车身的基本组成..........................................................................................9

2.1 白车身的定义.......................................................................................................9

2.2 白车身构造...........................................................................................................9

2.2.1 前车身..........................................................................................................9

2.2.2 地板............................................................................................................10

2.2.3 车身侧围及顶盖........................................................................................10

2.2.4 后部车身....................................................................................................10

第三章 轿车车身有限元模型的建立........................................................................12

3.1有限元理论概述..................................................................................................12

3.2车身有限元模型建模时的注意事项..................................................................14

　 3.2.1 模型的简化................................................................................................14

3.2.2 几何清理.....................................................................................................14

3.3.3 网格划分.....................................................................................................15

3.3.4 连接方式的模拟.........................................................................................16

3.3 白车身有限元模型.............................................................................................16

第四章 白车身计算模态............................................................................................17

4.1 计算模态分析理论...........................................................................................17

4.1.1 模态分析简介.............................................................................................17

4.1.2 模态分析理论.............................................................................................17

4.2 白车身模态参数的计算...................................................................................19

4.3 模态参数结果分析...........................................................................................26

第五章 重要连接点的动刚度分析............................................................................28

5.1 动刚度分析理论...............................................................................................28

5.2 重要连接点的讨论...........................................................................................29