摘 要

汽车是人们出行的重要交通方式，近年来，人们逐渐认识到能源危机和环境污染的严重性，新能源汽车必将在不久的将来取代传统燃油车。电能有能量来源多样等优点，电动汽车的发展和普及日益扩大，逐步被人们所接受。电池是电动汽车的重要部分，整车性能与电池优劣息息相关。本文针对电动轿车电池箱的轻量化和使用性能，进行了一系列工作。

首先分析了几款轿车的车型特点，根据轿车的基本布局确定将电池箱安装在地板下面，然后设计了外形和尺寸，建立了三维模型和有限元模型。运用OptiStruct对电池箱进行四种典型工况下的静态和模态分析。保证电池箱各部件的材料和结构基本满足使用要求，确定是否可以进一步优化以降低质量。模态分析表明，电池箱的一阶频率很低，说明结构强度不足。振型图显示，振动部位主要是电池箱上盖，故尝试在上盖表面添加加强筋来增加强度。添加加强筋后再次进行静态和模态分析，此次分析结果显示一阶频率有很大提升，满足使用要求。然后运用多目标综合拓扑优化的方法对电池箱进行优化设计，根据优化结果改进有限元模型。改进后再次进行静态和模态验证，结果表明电池箱的强度满足要求，刚度有了提高，质量有一定比例的下降，达到了轻量化的效果，证明了优化的可行性和有效性。

关键词：电池箱；静态特性；模态特性；多目标拓扑优化；轻量化

Abstract

Automobiles are an important means of transportation for people to travel. In recent years, people have gradually realized the seriousness of the energy crisis and environmental pollution, and it is imperative for new energy vehicles to replace traditional fuel vehicles. Electric energy has the advantages of diverse energy sources. The development and popularity of electric vehicles are expanding day by day and gradually being accepted by people. Battery is an important part of electric vehicle, the performance of the vehicle is closely related to the battery. In this paper, a series of works are carried out on the light weight and performance of the battery box of electric cars.

Firstly, the characteristics of several cars were analyzed, and the battery box was installed under the floor according to the basic layout of cars. Then, the shape and size were designed, and the three-dimensional model and finite element model were established. OptiStruct was used to conduct static and modal analysis of the battery box under four typical working conditions. Ensure that the material and structure of all parts of the battery box basically meet the use requirements, and determine whether further optimization can be made to reduce the quality. Modal analysis shows that the first frequency of the battery box is very low, which indicates that the structural strength is insufficient. The vibration diagram shows that the vibration part is mainly the upper cover of the battery box, so it is attempted to add reinforcing bars on the surface of the upper cover to increase the strength. The static and modal analysis was carried out again after the reinforcement was added. The analysis results showed that the first-order frequency was greatly improved to meet the requirements of use. Then, the finite element model is improved according to the optimization results. After the improvement, the static and modal verification were carried out again, and the results showed that the strength of the battery box met the requirements, the stiffness was improved, and the quality was reduced by a certain proportion, which achieved the lightening effect and proved the feasibility and effectiveness of the optimization.

Key Words： Battery box; Static characteristic; Modal characteristics; Multi-objective topology optimization; lightweight

目 录

第1章 绪论 1

1.1 选题背景及意义 1

1.2 国内外研究现状 1

1.3 本文的设计内容 2

第2章 电池箱结构设计及有限元模型的建立 3

2.1 电池箱结构初步设计 3

2.1.1 组成部件及尺寸布局 3

2.1.2 材料及厚度选择 4

2.2 电池箱有限元模型的建立 5

2.2.1 网格划分 5

2.2.2 模型装配 5

2.2.3 材料定义 8

2.2.4 部件属性赋予 8

2.3 本章小结 10

第3章 电池箱的静动态特性分析 11

3.1 创建载荷与工况 11

3.2 静态分析 13

3.2.1 加速工况分析 13

3.1.2 制动工况分析 15

3.1.3 转弯工况分析 16

3.1.4 跳动工况分析 18

3.2 模态分析 19

3.3 电池箱的初步改进及分析 23

3.3.1 结构初步改进 23

3.3.2 改进后模态分析 25

3.4 本章小结 26

第4章 电池箱的结构优化 27

4.1 多目标拓扑优化设计理论 27

4.1.1 优化流程介绍 27

4.1.2 数学模型的建立 27

4.1.3 静力学拓扑优化数学模型 27

4.1.4 动力学拓扑优化数学模型 28

4.1.5 多目标拓扑优化数学模型 29

4.2 电池箱的静力学单工况拓扑优化 29

4.2.1 加速工况 29

4.2.2 制动工况 30

4.2.3 转弯工况 30

4.2.4 跳动工况 30

4.3 电池箱动力学拓扑优化 30

4.4 电池箱多目标拓扑优化 30

4.5 电池箱的结构改进 32

4.6 本章小结 35

第5章 电池箱性能验证 36

5.1 静强度验证 36

5.2 模态验证 36

5.3 本章小结 38

总结与展望 39

全文总结 39

展望 39

参考文献 41

附录 优化后的有限元模型代码 42

致 谢 51

第1章 绪论

1.1 选题背景及意义

汽车在全球的数量越来越多，目前的汽车大多还是内燃机汽车，燃烧化石能源，排放的尾气中含有大量二氧化氮和氮氧化物，加剧着全球变暖和大气污染。且地球上的化石能源属于不可再生资源，以现在的消耗量持续下去，不久的将来人类将无能源可用。有统计表明，交通运输在石油能源的消耗中占到了56%的比例，其他几项分别是占比的居民商业，占比19%的工业，和占比9%的发电^[1]。可以看出交通运输在石油能源的消耗中占比最大，如果能将交通运输的能源从化石能源转换成其他可以再生或储藏量更大的能源，则可以缓解现在面临的问题。

目前，汽车行业正在谋求新能源汽车的发展，我国在新能源汽车方面的资金投入很大，政策也提供了很多方便，鼓励发展新能源汽车。电动汽车是新能源汽车的重要组成部分，现在各大厂商在电动汽车这块战地上的研发竞争也进行得十分火热。相比传统的燃油汽车，电动汽车的优势十分明显，主要体现在三个方面，一是能量利用率高；二是电能来源多样；三是可以夜间充电，合理使用电能，解决用电的峰谷不平衡问题。在电动汽车的普及方面，车辆的续航里程仍然是最大的阻碍。目前在提高汽车续航里程上主要有两个方面的措施，一是提高电池的性能，二是加强充电基础设施建设。很多地区对于购买新能源汽车的补助开始逐渐减少，更多的资金被投入到建设和维护充电设施上。