Abstract：Cellular metallic materials possess high specific stiffness, high specific strength and strong energy-absorbing capability, and have been used significantly as packaging material and crash material. In this paper, through numerical simulation and experimental study, four kinds of stress/force enhancement of cellular metallic materials under impact loads were researched as follows: 1) under small impact load, stress enhancement appears in cellular material and the reason is related to the irregularity of cell shape; 2) when cellular material is fully consolidated, stress enhancement happens because the material has been a dense solid and its property has changed completely; 3) stress enhancement happens before the cellular material is fully consolidated, and the reason lies in that when cellular material is undergoing plastic deformation, the plastic wave propagates 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 continuously increase with increasing impact velocities. In these situations, the third one is of great significant to be noted because this kind of stress enhancement may severely damage the substance under protection. This paper will provide a valuable reference for the crashworthiness design of cellular materials.
2014, Vol. 35 
