正面碰撞多刚体仿真及其计算机反求方法研究

Research on Multi-rigid-body Modeling and Computer Based Reversing Techniques in Full-Width Frontal Impact

车身耐撞性能评估和优化普遍采用有限元方法,计算量大、设计周期较长。提出了一种多刚体碰撞模型的建模及计算机反求方法,基于多刚体及塑性铰理论,从对标车型的有限元模型中获取刚度、质量、惯量、坐标等参数,建立了初始多刚体碰撞模型。通过定义碰撞加速度、速度、位移曲线置信度函数,利用计算机反求技术对刚度缩放因子进行反求得到修正模型。结果表明,多刚体模型与有限元模型相比,其精度相当,但计算效率显著提高。在概念设计阶段,采用多刚体模型,结合工程优化手段,可快速解决车身刚度分配及传力路径分析等关键技术难题,实现传力路径刚度的正向设计。

FEA are widely used to assess and optimize crashworthiness of vehicles,which costs a lot of computing resources and time. A simulation procedure of full-width frontal impact was presented based on multi-body theory and plastic joint principle. A benchmark finite element model（FEM） which had been identified by test was used to obtain joint stiffness,coordinates,rigid body mass and inertia. An original multi-body model（MBM） was built and demonstrated to be stiffer than FEM which needs to be optimized. By defining reliability function and using computer based reversing techniques,the MBM stiffness was modified and matched perfectly with FEM. The developed MBM is precise and efficient,thus it can be used in determining body stiffness distribution and in sequential design of force transmission path at early stage of vehicle design.