基于汽车碰撞仿真的点焊连接关系有限元模拟方法

FINITE ELEMENT MODELING OF SPOT WELDS BASED ON VEHICLE IMPACT

针对现在一般汽车碰撞有限元模型采用刚性梁作为点焊连接关系的模拟方法,通过仿真计算和参数影响分析,发现网格大小以及刚性梁与相连平面的夹角对于点焊的失效时间有着很大的影响,采用刚性梁单元模拟点焊连接关系是不稳定、不可靠的。提出以不依赖网格节点的弹—塑性梁作为点焊连接的有限元模拟方法,并经过仿真结果对比,发现弹—塑性梁单元对小网格尺寸不敏感,对于点焊失效时间的模拟是稳定、可靠的,因而更加适合在汽车碰撞仿真中对点焊连接关系进行模拟。

Considering the fact that spot-welds in most of the FE analyses of car crashes are modeled as a rigid beam, parameter study is performed by using FE calculation. It is found that the failure time of a rigid beam is highly dependent on the mesh size and the angle between the beam element and the connected surfaces, which means it is instable and unreliable to model the spot-weld to the rigid beam. Then, a new simulation technique of the spot-welds is put forward by using an elastic-plastic beam, which is independent of nodes. After simulation comparison, the elastic-plastic beam turns up to be a more suitable method to simulate the behavior of the spot-welds because of its insensitivity to small mesh size and stability and reliability in predicting the failure time of the spot-weld.