摘 要

汽车伴随着工业文明的出现而出现，同时它也是工业文明的标志之一，而汽车碰撞安全问题更是自汽车诞生之日起就成为制约汽车发展的关键问题之一。尤其是我国在近些年以来汽车保有量的持续增长，即使我国的道路交通状况有所改善，但交通事故所造成的所示却仍然不可忽视。据统计，在道路交通事故中，汽车侧面碰撞导致的事故占事故总量的31％左右。而在侧面碰撞中，由于车门距离乘员最近，乘员容易因车门变形而受伤。提高车门的碰撞性能对于保证乘员的安全和提高车辆的被动安全性能具有重大意义。因此，各大研究机构和汽车公司都加大了对汽车侧面碰撞的研究力度。

本文对冲击载荷下的汽车板件结构变形进行研究，故选用某轿车前门为研究对象。通过三维建模软件Catia并参照车门相关参数建立CAD模型。在CAD模型建立好之后,把整个车门文件导入有限元软件HyperMesh中进行前处理工作, 具体包括几何曲面的清理、网格的划分、单元质量的检查以及材料和约束的定义等,这为以后的计算仿真打下了基础。参照E-NCPA的柱状碰撞试验和FMVSS214的碰撞方式规定, 在LS-DYNA软件中进行求解计算后得到车门碰撞仿真的结果,从这些数据中提取分析车门的变形云图、车门的吸收能量能力、车门的侵入量、速度以及加速度随时间变化的图像等,从这些数据图像分析研究车门在整个侧面碰撞过程的耐撞性。根据前期做的车门碰撞仿真,提出从车门结构和材料两个方面进行优化仿真的方法。提取车门各个部件在碰撞过程中的吸能曲线，发现车门内板及车门外板吸能最大，从而推断出这两个部件对车门的耐撞性影响较大，并且由不同节点的位移曲线可以推断防撞杆也对车门的耐撞性有一定的影响，对车门内板、车门外板以及加强板从结构和材料方面进行优化改进。将优化后的车门参照E-NCPA的柱状碰撞试验和FMVSS214的碰撞方式的规定再次进行侧面碰撞仿真,提取某一节点的位移、速度以及加速度曲线随时间变化的图像，与优化前的曲线进行对比，发现优化后该节点的位移、速度以及加速度的峰值都有所减小，并且车门的质量也有所减小。从而证明改进车门后，其耐撞性得到了提升的同时，还实现了车门的轻量化。

关键词：车门；侧面碰撞；有限元仿真；被动安全性；耐撞性

Abstract

The appearance of the automobile along with the appearance of industrial civilization is also one of the symbols of industrial civilization. The problem of automobile collision safety is one of the key issues restricting the development of automobiles since the birth of the automobile. In particular, China’s car ownership has continued to increase in recent years. Even though China’s road traffic conditions have improved, the traffic accidents still cannot be ignored. According to statistics, in a road traffic accident, accidents caused by car side collisions account for about 31% of the total accidents. In the case of a side collision, the occupant is easily injured by the deformation of the door because the door is closest to the occupant. Improving the crash performance of the vehicle door is of great significance for ensuring the safety of the occupants and improving the passive safety performance of the vehicle. Therefore, major research institutions and automobile companies have increased their research on the side impact of automobiles.

In this paper, the structural deformation of automotive panels under impact loading is studied. Therefore, the front door of a sedan is selected as the research object. The CAD model is built by 3D modeling software catia and with reference to door related parameters. After the CAD model is established, the entire door file is imported into the finite element software HyperMesh for preprocessing, including the cleanup of geometric surfaces, the division of the mesh, the check of the unit quality, the definition of materials and constraints, etc. The calculation simulation lays the foundation. Referring to the E-NCPA column crash test and the FMVSS 214 collision mode specification, the result of the door collision simulation was obtained after solving calculations in the LS-DYNA software. From these data, the door's deformation cloud diagram, the door's energy absorption capability, and the door were extracted and analyzed. The image of intrusion, velocity, and acceleration over time, etc., from these data images analyzes the crashworthiness of the door during the entire side impact process.According to the door collision simulation done in the previous period, the method of optimizing simulation from the door structure and material was proposed. The energy absorption curve of various parts of the vehicle door during the collision was extracted. It was found that the energy absorption of the inner door panel and the outer panel of the door was the largest. It was inferred that these two components had a greater impact on the crashworthiness of the vehicle door, and the displacement curves from different nodes could be It is inferred that the reinforcing plate also has a certain influence on the crashworthiness of the door, and optimization and improvement are made on the structure and material of the door inner panel, the door outer panel, and the reinforcing panel. The optimized door was referenced to the E-NCPA column crash test and the FMVSS 214 collision mode. The side crash simulation was performed again to extract the image of the displacement, velocity, and acceleration curve of a certain node over time, and compared with the curve before optimization. After the optimization, the peak value of the displacement, velocity, and acceleration of the node has been reduced, and the quality of the door has also been reduced. As a result, it has been proved that after the improvement of the door, the crashworthiness has been improved and the weight of the door has also been achieved.

Keywords: doors;side impact;finite element simulation;passive safety; crashworthiness

目 录

摘 要 I

Abstract II

第1章 绪论 1

1.1 我国道路交通现状 1

1.2 研究意义 2

1.3 汽车碰撞安全法规 4

1.4 侧面碰撞的国内外研究现状 5

1.5 侧面碰撞的研究方法 6

1.5.1 试验法 6

1.5.2 计算机仿真方法 8

1.6 本文研究内容 9

第2章 碰撞有限元计算的基本理论 11

2.1 有限元法的理论基础 11

2.2 碰撞分析软件简介 12

2.3 有限元方法的分析过程 13

2.4 汽车碰撞有限元理论 14

2.4.1 基于Lagrang的有限元思想 14

2.4.2 时间积分方式——中心差分法 16

2.4.3 接触碰撞计算 17

2.4.4 沙漏控制 18

2.5 本章小结 19

第3章 车门碰撞的仿真及结果分析 20

3.1 基于Hypermesh的模型前处理 20

3.1.1 CAD几何模型的确立 20

3.1.2 网格的划分和质量检查 20

3.1.3 材料的定义 22

3.1.4 连接方式及约束条件定义 22

3.1.5 碰撞圆柱的确定 23

3.1.6 接触及沙漏定义 23

3.2 车门侧面碰撞仿真结果分析 24

3.2.1 仿真结果 24

3.2.2 车门吸能能力 27

3.2.3 车门侵入量 28

3.2.4 侵入速度 30

3.2.5 侵入加速度 31

3.3 本章小结 32

第4章 汽车车门的改进设计研究 33

4.1 车门的改进 33

4.2 仿真结果与分析 34

4.2.1 车门侵入量 34

4.2.2 侵入速度 35

4.2.3 侵入加速度 36

4.3 本章小结 37

第5章 总结与展望 38