Modeling the perforation failure of honeycomb sandwich structures through numerical homogenization

In this study, the perforation failure of honeycomb sandwich structures is numerically simulated by using homogenized equivalent model. The high velocity impact behavior of aluminum honeycomb core with reinforced carbon/epoxy face sheets is modeled by using commercial finite element (FE) analysis code AUTODYN-3D. It is observed that the detailed three dimensional FE modeling of honeycomb core is complex, time consuming and computationally expensive. A simplified hexagonal honeycomb equivalent numerical model with relatively less computational time and acceptable degree of accuracy is proposed in this paper. The equivalent numerical model is based on P-alpha (Pα) equation of state for porous materials. In this model, it is assumed that honeycomb core is isotropic homogeneous porous medium in which all the pores are uniformly distributed. For the purpose of validation, the simulation results of detailed and equivalent honeycomb numerical models are compared with available experimental results in terms of ballistic limit, energy absorption, residual velocity and contact time. The results show that the equivalent honeycomb model closely predicts the perforation behavior for various impact velocities and takes considerably less computational time than detailed honeycomb model.