Dynamic deformation and failure process of quasi-closed-cell aluminum foam manufactured by direct foaming technique

Abstract

The application of cellular structure for energy dissipation requires the investigation on the deformation and failure process of the foam under dynamic loading. In this study, the split-Hopkinson pressure bar technique with high speed video camera was used to directly observe the dynamic deformation in quasi-closed-cell aluminum foam fabricated by an in-house direct foaming methodology. The characterization of cellular structure was first performed on the developed aluminum foam, indicating that the cell size follows a log-normal distribution. The measurements revealed that the deformation mode varies with the strain rate. After that an experimentally validated X-ray micro-computed tomography based 3D finite element model of the as-fabricated specimen was established to predict the stress distribution and deformation history under impact loading, and correlated to the experimental observations to explore the deformation mechanisms. It was found that shear band is formed after peak stress. The dynamic deformation and failure process of the quasi-closed-cell aluminum foam result from the coexistence of cell wall bending and buckling, cell collapse and shear traction induced tearing breakage.