Effect of loading rate on the compressive properties of open-cell metal foams

Abstract

Based on the three-dimensional tetrakaidecahedron model, the dynamic compressive properties of the open-cell aluminum foam was investigated using the finite element (FE) method. Qualitatively analyzing the effects of the impact velocity and the relative density on the deformation modes, plateau stress, densification strain and energy absorption of the open-cell foam, it is found that the different impact velocity causes different failure modes and patterns: the foam follows the kind of bending–buckling deformation pattern under the low impact velocities while follow the kind of buckling–bending–buckling one under high impact velocities. Two types of the deformation mechanisms have been observed by the macroscopic stress–strain responses, and it transpires that the crushing deformation of metallic foams tends to the type I response under the lower impact velocity; while it tends to the type II response under the higher impact velocity. The results also indicate that both the plateau stress and the densification strain energy are not dependent on crushing velocity for the low relative density, but loading-rate sensitivity for the high relative density foam. Moreover, both of them can be improved by increasing the foam relative density. The relative density has little effect on the densification strain, while the impact velocity has greater influence on the densification strain but with no simple monotonous change