中文摘要：

多孔材料由于具有高比刚度、高比强度、强的吸收能量的能力等优点使其作为包装材料和防撞材料在汽车工业及航空航天等领域大量使用．论文经过数值模拟和实验研究发现在冲击荷载作用下多孔金属材料中会出现以下几种应力增强现象：（1）在较小冲击载荷作用下出现的应力增强，其原因是多孔材料胞孔形状的不规则性引起的．（2）多孔材料完全密实化以后出现的应力增强，其原因是多孔材料变成致密的固体后，由于冲击荷载仍就存在和惯性的作用使多孔材料的速度不断增大而导致输出端应力大于加载端应力．（3）多孔材料未完全密实化时出现的应力增强，其原因是多孔材料产生塑性变形以后，塑性波速随应变增大而增大，即在加载过程中高幅值扰动的传播速度大于其前方的低幅值扰动的传播速度，从而出现应力增强．（4）冲击端出现的应力增强．这与众所周知的冲击理论相一致，冲击端的应力随着冲击速度的增加而增加．在以上几种应力／力增强现象中，前三种应力增强现象在使用多孔材料作为防撞性目的时需特别注意，此时会对被保护物体造成更严重的伤害．论文可以为多孔材料防撞性设计与运用提供一定的参考．

英文摘要：

Cellular metallic materials possess high specific stiffness, high specific strength and strong energy-absorbing capacity, and have been used significantly as packaging and crash materials. In this paper, four kinds of stress/force enhancement of cellular metallic materials under impact loads were researched through numerical simulation and experimental study.- （1） stress enhancement appears under small impact loads and the reason is related to the irregularity of celi shape; （2） stress enhancement happens when cellular material is fully consolidated, because after the material becomes a dense solid, it moves faster under the continuous effect of impact load and at the action of inert and the output stress is greater than the input one; （3） stress enhancement also happens before the cellular material is fully consolidated, and the reason lies in that when cellular material is undergoing plastic deformation, the plastic wave propa gates increasingly fast with increasing strain and when the propagation velocity of high amplitude perturbation is greater than that of low amplitude perturbation in the front, stress enhancement forms over a period of time; （4） stress enhancement appears at impact end because according to the well known shock-wave propagation theory, stresses at impact end increase continuously with impact velocity increasing. In these situations, the first three ones are of great significant to be noted because it may severely damage the substance under protection. This paper will provide a valuable reference for the crashworthiness design of cellular materials.