Dynamic Mechanical Behavior of Graded Metallic Foams Based on Lagrangian Analysis Method

The Lagrangian analysis method was employed to investigate the deformation mechanism and stress response of graded metallic foams. The mesoscopic finite element models of the graded metallic foams with five different density gradient parameters were constructed by the 3D-Voronoi technique, and the corresponding Taylor numerical tests were performed under high-speed impact, and the particle velocity distributions of different graded foams were obtained. By combining the Lagrangian analysis method with the results of Taylor numerical tests, the effects of density gradient parameters on the local strain distribution, stress distribution, shock wave propagation and attenuation of metallic foams under high-speed impact were investigated. The results show that the metallic foams with negative density gradient have better resistance to vertical deformation than those with positive density gradient, and the deformation degree decreases with the decrease of the density gradient parameter. The local densification stress distribution of the metallic foams with negative density gradient decreases linearly, and the maximum local densification stress increases with the decrease of the density gradient parameter. The metallic foams with negative density gradient have high load bearing capability near the impact end. The local densification stress distribution of the metallic foams with positive density gradient has a plateau stage, and the maximum local densification stress is less than metallic foams with negative density gradient.