Dynamic indentation and penetration of aluminium foams

Failure of metal foams caused by dynamic indentation and penetration is very common in practice, such as light-weight structural sandwich panels, packing materials and energy absorbing devices. Rational application of these materials requires a sound understanding of deformation and energy absorption mechanisms of the aluminium foams as well as the effect of impact velocity. In this study, following experimental investigations into compression, tension, sharing and indentation of CYMAT aluminium foams of various densities, a finite element (FE) analysis using ABAQUS is conducted for dynamic indentation process of aluminium foams under a rigid, flat-headed indenter. Two methods of applying impact velocities are considered: the indenter is pushed into the foam at a constant velocity through the whole process or with an initial velocity which then decreases with indentation. Two energy dissipation mechanisms are considered: compression of the foam ahead of the indenter and fracture along the indenter edge. Effect of impact velocity is noted on the size of a localized deformation and the total energy absorbed. A plastic structural shock theory developed by previous researchers is applied to calculate the resistance force with indentation depth during indentation process and fair agreement is obtained between the analytical and numerical results.