基于有限元法的事故车辆车身塑性变形计算系统

发布时间：2018-01-30 22:29

本文关键词： 事故车辆塑性变形有限元法壳体结构　出处：《长安大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着我国汽车保有量的激增,道路交通事故已成为一大社会问题,采用计算机技术处理道路交通事故成为趋势,并取得了很好的效果。事故发生后最直观的体现就是车身的塑性变形,对车身塑性变形进行分析计算可以为交通事故处理部门提供有用的参考信息。目前,常用的事故车辆车身塑性变形的计算方法是将测量的塑性变形根据碰撞刚度系数求解,这种方法需要大量的实车碰撞试验来获得车辆在不同方向的碰撞刚度系数,需要大量的人力、物力、财力,我国并没有建立起汽车碰撞刚度系数的数据库,因此,研究一种普遍适应性的事故车辆车身塑性变形的计算系统,具有重要的工程意义。本文在分析车辆发生碰撞后壳体结构变形过程的基础上,建立基于VC++平台和有限元理论知识的事故车辆车身壳体结构塑性变形的计算系统,依据有限元理论中网格划分的原则,将复杂的车身壳体结构塑性变形离散成若干个微小单元,通过每个单元的力学参数建立起连续体的力平衡方程,计算节点力,并计算出等效载荷和等效塑性变形能。最后通过实例完成系统实效性的检验。对车身塑性壳体结构进行了研究,构造薄板单元,以薄板单元组成的折板来代替壳体结构,根据车辆壳体结构进入塑性变形后,应力与应变关系的变化,采用增量法,分别建立了薄板单元在平面应力状态下和弯扭应力状态下的单元刚度矩阵模型。深入研究结构总刚度矩阵的特征,设计结构总刚度矩阵的一维压缩存储方法,针对节点力平衡方程的构造形式和求解过程,提出在一维存储总刚度矩阵的基础上正向求解节点力的方法。开发事故车辆车身塑性变形的计算系统。以VC++为平台,设计系统的前处理模块,包括单元、节点编码,节点位移生成与提取两个子模块;建立节点力计算模块,包括平面应力状态下计算和弯扭应力状态下计算两个子模块;针对车身壳体结构受力和塑性变形能的计算特点,分别建立等效载荷和等效塑性变形能的后处理模块。最后结合事故实例,进行系统的检验和使用流程的介绍。
[Abstract]:With the rapid increase of vehicle ownership in China, road traffic accidents have become a major social problem, the use of computer technology to deal with road traffic accidents has become a trend. And achieved good results. The most intuitive embodiment of the accident is the plastic deformation of the body. The analysis and calculation of the plastic deformation of the body can provide useful reference information for the traffic accident treatment department. The commonly used method for calculating the plastic deformation of vehicle body is to calculate the measured plastic deformation according to the impact stiffness coefficient. This method requires a large number of real vehicle impact tests to obtain the impact stiffness coefficient of vehicles in different directions. It requires a lot of manpower, material and financial resources. There is no database of vehicle collision stiffness coefficient in China. Therefore, it is of great engineering significance to study a universal adaptive calculation system for the plastic deformation of the vehicle body. This paper analyzes the deformation process of the shell structure after the vehicle collision. Based on VC platform and finite element theory knowledge, the plastic deformation calculation system of accident vehicle body shell structure is established, according to the principle of mesh division in finite element theory. The plastic deformation of the complicated body shell structure is discretized into several tiny elements, and the force balance equation of the continuum is established by the mechanical parameters of each element, and the node force is calculated. The equivalent load and the equivalent plastic deformation energy are calculated. Finally, the effectiveness of the system is tested by an example. The structure of the body plastic shell is studied and the thin plate element is constructed. The laminated plate is used to replace the shell structure. The incremental method is adopted according to the change of the stress-strain relationship between the vehicle shell structure and the plastic deformation. The element stiffness matrix models of thin plate element under plane stress and bending and torsional stress are established respectively. The characteristics of total stiffness matrix of structure are studied and the one-dimensional compression storage method of total stiffness matrix is designed. The construction form and solution process of the nodal force balance equation are discussed. Based on the one-dimensional storage of the total stiffness matrix, a forward method to solve the node force is proposed. The calculation system of the plastic deformation of the vehicle body is developed. Based on VC platform, the pre-processing module of the system, including the unit, is designed. Node coding, node displacement generation and extraction two sub-modules; The nodal force calculation module is established, which includes two sub-modules: plane stress calculation and bending and torsional stress calculation. According to the calculation characteristics of the stress and plastic deformation energy of the body shell structure, the post-processing modules of equivalent load and equivalent plastic deformation energy are established respectively. Finally, combined with the accident example, the system inspection and application flow are introduced.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U491.31

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