【作者】 邹正宽；

【导师】 张维刚；

【作者基本信息】 湖南大学 ， 车辆工程， 2010， 硕士

【摘要】 汽车碰撞安全性是现代汽车工业研究的关键内容之一,而如何提高汽车在碰撞事故中的耐撞性能是汽车安全性设计中的核心问题。作为最传统、最有效的吸能元件一金属薄壁构件,在车身吸能装置中已得到了广泛的应用。而在汽车正面碰撞过程中,薄壁前纵梁是主要的变形吸能结构。汽车碰撞的能量由薄壁前纵梁的塑性变形来吸收,汽车的碰撞加速度由车辆前部吸能结构的平均压缩载荷来决定,而薄壁前纵梁结构在汽车压缩变形中起到了主导作用,前纵梁的变形和吸能状况在很大程度上决定了整车的耐撞性能好坏。因此,前纵梁的结构耐撞性设计在汽车正面碰撞中具有十分重要的工程意义。本文对国内外汽车结构耐撞性研究现状进行了总结分析；分析了网格单元大小、时间步长、材料应变率效应、接触摩擦系数等影响碰撞仿真结果的几个重要因素；探讨了冲击速度(外载)、轴向长度、材料强度、材料厚度及截面尺寸等对方形薄壁梁变形模态及吸能性能的影响,并在此基础上,研究了简化纵梁的变形模态及吸能性能；利用方形薄壁直梁变形模态的研究结果对纵梁进行了结构改进设计,取得了较好效果；最后探讨了正面碰撞中乘员损伤机理,确定正面碰撞设计原则,对汽车纵梁等前舱关键部件进行了改进设计,改进结果有效地降低了整车碰撞加速度峰值,控制了踏板组及防火墙的侵入量。证明本文所提出的设计与改进方法是适用和有效的,具有重要的工程实用意义和价值。更多还原

【Abstract】 Vehicle passive safety is one of the key problems for the automobile industry.How to improve the crashworthiness of vehicles has been the key issue of the automotive safety. The thin-walled metallic components---the most conventional and effective energy-absorbtion device, have been widely used in the automotive design and manufacture. The thin front rail is the main deformation and energy-absorbption structure in frontal crash. The crash energy of the car was absorpted by the plastic deformation of thin-walled front rail and the acceleration of the car was determined by the average compressive load of the vehicle front collision energy absorbing structure,while the thin-walled structure has played a leading role in the compression deformation of the car. The performance of the vehicle crashworthiness is determined by the deformation and the energy-absorption of the front rail. Therefore,the structural design of vehicle front rail crashworthiness in the frontal crash has a great engineering significance.This paper starts with summarizing the condition of study crashworthiness of vehicle with domestic and overseas. Then this paper analyse the several important factors which affect the crash simulation results,such as:the grid cell size, timestep setting,strain-rate effects, contact friction coefficient and material Stamping; The paper discusses the distortion wavelength and the energy absorption characteristic of square thin-walled straight beam structures’ crashworthiness, which was affected by the following factors:impact speed (exterior load)、axes length material intensity、material thickness、section size and so on. On the basis of the above work, the paper studies the collapse mode and energy absorption characteristic of simple frontal crash rail; Using the production of the above work, the paper makes some improvements on the frontal crash rail. In further research, the paper discusses the mechanism of occupants’ injury and improves on key components, such as the frontal crash rail, based on the frontal impact design principles. The result shows that it cut down the peak acceleration of the car effectively and controll the intrusion of pedal group and fire wall.The result manifestes that the design and methods in the paper are appropriate and effective, so the research has a important significance impact on the engineering field.更多还原