Dynamic Properties of Density Graded Thin-Walled Metal Hollow Sphere Arrays

In order to improve the dynamic properties of uniform cellular materials, a 2D density graded metal hollow sphere (MHS) array is investigated by explicit finite element method (FEM) simulation of in-plane crushing of sphere systems. The grading is established by changing sphere wall thickness. Pattern transformation from a square lattice to a hexagonal one is formed at a low impact velocity as observed in experiments. The emphasis is placed on the influence of gradient profile on the energy absorption of materials under high impact velocities. The relation between material dynamic responses and gradients as well as impact velocities is established for design purpose.