Experimental and Theoretical Investigation on Dynamic Properties of Metal Foam

Abstract

In this study, two kinds of dynamic compression tests were conducted using direct-impact Hopkinson pressure bar (DHPB) facilities, i.e., the bullet with foam specimen was shot on the transmission bar, or the foam specimen was mounted at the end surface of the transmission bar and was hit by a bullet directly. Stress enhancement and localized deformation, as two mainly dynamic properties of metal foam, were observed in the experiments. Then, dynamic locking strain is proposed in order to better describe the feature of foam’s localized deformation field during the impact process. A rigid- perfectly-plastic-dynamic-locking strain model (R-P-P-D-L model) is developed to study the dynamic properties of the foams. The parameters included in this model are determined by 3D numerical Voronoi model and experiments. Comparing the predictions from R-P-P-D-L model with numerical results and experimental results, it is found that the R-P-P-D-L model can capture the main deformation mechanisms of the foam in dynamic compression, and provide a more precise prediction than R-P-P-L model. Furthermore, the stress enhancement of foam with the relative density and the impact velocity are discussed using the R-P-P-D-L model.