Dynamic response of functionally graded cellular materials based on the Voronoi model

Dynamic behavior of Voronoi cellular materials with density gradient subjected to constant velocity impact was simulated and analyzed by employing the Ls-dyna 971. The introduction of density gradients may significantly influence the global performance of cellular materials, so in order to probe the failure mechanism and stress transmission, firstly, deformation modes of graded Voronoi models are investigated in details. The approach of capturing the first critical velocity of the deformation mode transformation in uniform cellular materials was extended to the graded cases. Meanwhile, a new method based on the local strain was developed to determine the second critical velocity. Afterwards, the variations of the crushing stress and the plateau stress at both the impact and stationary sides were taken into consideration in the study. Furthermore, the density gradient was introduced into the shock wave theory based on R-P-P-L model to predict the response of the graded cases. Additionally, the feasibility to use the graded materials as a protective coating and the variation of densification strain were sketched. This research may provide valuable insight into engineering applications of the graded cellular materials.