显式有限元法在车辆耐撞性研究中的应用

Explicit finite element method for vehicle crashworthiness

基于连续介质理论 ,通过建立车辆碰撞的控制方程 ,在此基础上得到与控制方程和边界条件等效的“弱积分”形式。通过空间和时间的显式离散 ,得到了车辆碰撞的有限元方程。采用动力显式积分方法 ,使位移计算显式化 ,避免了由材料、几何、边界高度非线性因素引起的计算收敛问题 ,并讨论了薄板单元的 Courant稳定性条件。提出了“端部吸能结构纵向压缩变形、纵向吸能”的耐冲击结构设计的思路 ,并对算例进行了数值模拟。结果表明 ,该设计方法可以实现车辆结构自身被动安全保护的目的 ,显式有限元数值模拟方法是车辆耐撞性研究的有效方法之一 ,但是需要进行部分撞击试验 。

Based on the continuum mechanics, governing equations of vehicle collisions were set up and the weak form of the equilibrium equations was found. Through explicit discretization of space and time, finite element equation was obtained. By utilizing dynamic explicit integral, nodal displacements were calculated explicitly, which avoids the convergence problem caused by highly non-linear factors including material, geometry, boundary. Also the Courant stability condition for thin-shell element was discussed. The design method of crashworthy structure longitudinal compress deformation, longitudinally absorbing energy was proposed and numeric simulation on an example was carried out. The results show that the design method can realize self-structure passive safety and the explicit finite element method is an effective way for structure crashworthiness research. But it is necessary to carry out some crash tests so as to modify the numeric model and!improve simulation accuracy.5 figs,8 refs.