Simulation study on the effect of trapped gas on the dynamic compressive stress enhancement of aluminium foam

Abstract

To investigate the effect of trapped gas on the dynamic compressive stress enhancement of aluminium foam, a three-dimensional solid aluminium foam model is built using the aluminium foam modelling plug-in based on the Voronoi model. The dynamic compression of aluminium foam in the range of 1–4000 s−1 strain rate is simulated using the CEL method in the ABAQUS simulation software. The stress-strain response and energy absorption performance of aluminium foam at different strain rates are compared and analysed. The mechanism of gas stress enhancement is investigated, and the flow mode of the trapped gas, the gas pressure distribution inside the cell during compression and the effect of trapped gas on the cell structure deformation of aluminium foam are analysed. Considering the higher-order strain term and strengthening effect of trapped gas on the cell structure of aluminium foam, an analytical prediction equation, including structural stress enhancement terms, is established. The research results show that aluminium foam has clear strain rate sensitivity, and the gas stress enhancement effect cannot be ignored at high strain rates. The interaction between the trapped gas and cell structure will increase the local equivalent plastic strain and structural stress, which is the main reason for the significant gas stress enhancement effect at the densification stage of aluminium foam at high strain rates. The gas stress enhancement analytical prediction equation, including the structural stress enhancement term, can accurately predict the gas stress enhancement at different strain rates.