Three-dimensional Voronoi-based simulation study of stepwise density-graded aluminum foams: Buffering and energy absorption performance analysis

Abstract

Three-dimensional Voronoi models are built to analyze the buffering and energy absorption performance of stepwise density-graded aluminum foams during quasi-static and dynamic compression. The validity of the aluminum foam model with selected mesostructure and simulation parameters is verified by the correlation between the experimental and numerical results. Strain-stress responses, deformation propagation, and energy absorption capabilities are compared and analyzed to probe the deformation mechanisms and stress transmission. The results show that there are three deformation modes: quasi-static mode, transitional mode, and dynamic mode, which are formed successively with increasing compression velocity. The method of obtaining the first critical velocity of the deformation mode transformation in two-dimensional stepwise density-graded aluminum foams is extended to the three-dimensional cases. Meanwhile, a new method based on the deformation concentration is developed to determine the second critical velocity. The different stepwise density graded aluminum foams exhibit similar performances under quasi-static mode, but exhibited significant differences under dynamic mode. However, a negative gradient of aluminum foam is advantageous for reducing the stress on the support end and optimizing the energy absorption under dynamic mode.