Dynamic Impact of High-Density Aluminum Foam

Abstract

High-density aluminum foam can provide higher stiffness and absorb more energy during the impact Obtaining the constitutive law of such foam requires tri-axial tests with very high pressure, where difficulty may arise because the hydrostatic pressure can reach more than 30 MPa. In this paper, instead of using tri-axial tests, we proposed three easier tests—tension, compression and shear to obtain the parameters of constitutive model (the Deshpande–Fleck model). To verify the constitutive model both statically and dynamically, we carried out additional triaxial tests and direct impact tests, respectively. Based on the derived model, we performed finite element simulation to study the impact response of the present foam. By dimensional analysis, we proposed an empirical equation for a non-dimensional impact time  ${\bar{t}}_{\mathrm {d}}$, the impact time divided by the time required for plastic wave travelling from the impact surface to the bottom surface, to determine the deformation characteristic of the aluminum foam after impact. For the case with ${\bar{t}}_{\mathrm {d}}\le 1$, the deformation tends to exhibit a shock-type characteristic, while for the case with ${\bar{t}}_{\mathrm {d}}>5$, the deformation tends to exhibit an upsetting-type characteristic.