论文总字数：91261字

摘 要

随着环境污染以及能源危机的日益加剧，汽车行业逐渐由传统燃油汽车向新能源汽车的方向转型升级。由于电动汽车有着噪声小、无污染、清洁能源、低排放的优点，因此其产业也得到国家的重视。但是随着电动汽车需求量的增长，纯电动车在使用过程中的一些问题也逐渐凸显，其中由于电动汽车的车桥与传统燃油汽车的结构形式、使用性能、布置形式、寿命影响因素等有很大区别。因此，对电动汽车车桥的可靠性展开研究十分有必要。

本文以电动小巴车为例，参考曙光汽车有限公司自主研制的同轴直联车桥为研究对象，将有限元分析方法和可靠性分析方法有机结合起来，以此来分析其可靠性程度。

首先，对现有的电动汽车驱动后桥结构形式进行详细的对比分析，在对比分析的基础上选取同轴直联车桥为研究对象，结合电动小巴车的实际车型参数，例如最大车速，风阻系数等条件，对其驱动电机及传动系部件进行参数匹配。根据车桥不同工况下的受力及工作环境综合分析，选择暴露在室外环境缺少保护且易发生疲劳从而断裂的桥壳作为设计和可靠性分析的主体对象。

其次，应用Solid works对同轴直联车桥零部件进行三维建模，然后利用有限元分析软件ANSYS Workbench结合相关台架试验标准，分析在四种极限工况下车桥的应力和位移，并根据应力应变云图找到车桥薄弱位置。

再次，依据桥壳材料特性及实际加工工艺对桥壳材料的 S-N曲线进行了修正，第三，基于修正的S-N曲线，参考相关标准，在Workbench中的疲劳分析模块利用循环疲劳载荷加载，按照线性累积损伤理论进行车桥寿命的评估和安全系数的仿真分析。找到疲劳寿命的薄弱部位。

最后，对车桥进行可靠性分析。考虑到车桥本身材料属性、受载情况等对车桥寿命的影响，建立车桥可靠性模型。应用ANSYS Workbench中的Six Sigma模块对车桥进行可靠性分析。以车桥材料的弹性模量，泊松比，屈服强度，抗拉强度等属性以及单边载荷作为可靠性分析的输入参数，选择车桥的最大变形量和最低使用寿命作为输出变量来评估车桥的可靠性。在此基础上对车桥进一步进行优化设计，并确定最终的结构模型， 同样对其进行仿真分析，结果证实改进后模型的可靠性。

通过对电动小巴车同轴一体式车桥进行极限工况有限元分析、疲劳寿命分析、可靠性分析等方面的研究，得到了可以提高电动小巴车车桥疲劳寿命，安全系数以及可靠性的设计方案，为电动汽车车桥可靠性的相关研究提供了理论依据，具有实际的工程意义。

关键词：电动汽车；可靠性分析；有限元分析；驱动桥；疲劳寿命

Abstract

With the increasing environmental pollution and energy crisis, the development of the automotive industry has gradually transformed and upgraded from traditional fuel vehicles to new energy vehicles. Because pure electric vehicles have the outstanding advantages of low noise, no pollution, clean energy and low emissions, their industry has received increasing attention from the country. However, as the demand for electric vehicles continues to grow, some problems in the use of pure electric vehicles have gradually become more prominent. Among them, due to the structure, performance, layout, and life-influencing factors of the bridges of electric vehicles and traditional fuel vehicles There is a big difference. Therefore, it is very necessary to study the reliability of electric vehicle axles.

This article takes electric minibus as an example, and refers to the coaxial direct-connected axle independently developed by Shuguang Automobile Co., Ltd. as the research object, and combines the finite element analysis method and the reliability analysis method to analyze its reliability.

First of all, a detailed comparative analysis of the existing electric vehicle drive rear axle structure form is carried out. On the basis of the comparative analysis, the coaxial direct axle is selected as the research object, combined with the actual model parameters of the electric minibus, such as the maximum speed Conditions such as wind resistance coefficients are used to match the parameters of its drive motor and transmission system components. According to the comprehensive analysis of the stress and working environment of the axle under different working conditions, the axle shell exposed to the outdoor environment lacking protection and prone to fatigue and fracture is selected as the main object of design and reliability analysis.

Secondly, use Solid works to carry out three-dimensional modeling of coaxial direct axle components, and then use the finite element analysis software ANSYS Workbench combined with relevant bench test standards to analyze the stress and displacement of the axle under four extreme working conditions Find the weak position of the axle according to the stress-strain cloud diagram.

Third, the SN curve of the bridge shell material was modified according to the characteristics of the bridge shell material and the actual processing technology. Third, based on the modified SN curve, referring to the relevant standards, the fatigue analysis module in Workbench used cyclic fatigue load to load, Linear cumulative damage theory is used to evaluate the axle life and simulate the safety factor. Find the weak parts of fatigue life.

Finally, the reliability of the axle is analyzed. Considering the influence of the material properties and load conditions of the axle itself on the life of the axle, an axle reliability model is established. The Six Sigma module in ANSYS Workbench is used to analyze the reliability of the axle. Taking the elastic modulus, Poisson's ratio, yield strength, tensile strength and other properties of the axle material and unilateral load as the input parameters for reliability analysis, the maximum deformation and the minimum service life of the axle are selected as output variables to evaluate the vehicle Bridge reliability. On this basis, the vehicle axle is further optimized and the final structural model is determined. The simulation analysis is also carried out, and the results confirm the reliability of the improved model.

Keywords: electric vehicle; reliability analysis,;finite element analysis,;drive axle,;fatigue life

table of Contents

Summary I

Abstract II

Chapter 1 Introduction 1

1.1 Purpose and significance of research 1

1.1.1 Research purpose of the subject 1

1.1.2 Research significance 2

1.2 Research Trends at Home and Abroad 2

1.3 Main research content 4

Chapter 2 Axle Assembly and Parameter Matching of Electric Minibus 5

2.1 Overview of coaxial integrated axle 5

2.2 Parameter matching of axle power transmission system 7

2.2.1 Parameter matching of drive motor 7

2.2.2 Drive axle driveline parameter matching 9

2.3 Structural analysis of the axle housing of electric minibuses 10

2.4 Chapter Summary 11

Chapter 3. The establishment of the 3D model of the coaxial integrated drive axle and the FEA under the limit working condition 11

3.1 Establish a three-dimensional model of the axle 11

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