Plastic Collapse of Thin-Walled Curved Structures Due to Clashing

本课题采用实验和数值模拟相结合的方法，对汽车基本部件--薄壁曲面结构的吸能特性进行了研究，提出了估算结构吸能特性的实验方法。实验中使用了碰撞试验机。通过对冲击器上的加速度计的输出数据进行积分来计算试件的位移，并从冲击器上的称重传感器测量冲击载荷。从位移-载荷曲线可以很容易地估计能量吸收的特征。通过对细长圆柱体的纵向冲击实验，得到了圆柱体能量吸收的基本现象。在这些实验中，圆柱体出现了轴向模式、轴向模式等六种模式，其中吸收能量最大的模式是圆柱体端部折叠弹性铰时的模式。得到了各简谐振型的位移与吸收能近似成正比，并编制了三维弹塑性动力响应分析程序。对于非线性材料或结构的有限变形问题，由于该程序采用了不需要迭代计算的显式有限差分方法，因此计算时间短。

In the present project, energy absorption of thin-walled curved structures which are basic parts of automobiles, was investigated by experiments and numerical simulations.The experimental techniques of estimating the characteristics of energy absorption for structures was considered. The clash test machine was used in the experiments. The displacements of test pieces were calculated by the procedure of integrating output data from the accelerometer on the impactor, and the impact loads were measured from the load-cell on the impactor. The characteristics of the energy absorptions can be easily estimated from the displacement-load diagrams.The longitudinal impact of thin-&, talled cylinders were experimented to obtain fundamental phenomena of the energy absorptions of the crxish. In these experiments, six kinds of the crush-modes of the cylinders appeared, for example, axial mode, xinaxial modes etc. The mode leaving largest absorption energy is the one when the end of the cylinder folds bacit xrithotit plastic hinges. It is obtained that the displacements of every crxish modes are approximately proportional to absorption energies.The program for the analysis of the tiio-dimensional dynamic elasto-plastic responses has been developed. At the case of nonlinear material or finite deformation problems of structures, the numerical restilts are computed in short time, because the explicit finite difference method without iterative calculations is applied to this program.