Drop-weight impact behavior of honeycomb sandwich panels under a spherical impactor

Indentation response and energy absorption property of honeycomb sandwich panels subjected to drop-weight impact under a spherical impactor were investigated. Experiments were conducted using a pendulum-impact system. A three-dimensional finite element model with micro-structure considered was built and validated. In conjunction with experimental and numerical methods, analytical models of indentation response and energy balance specifically aimed to solve problems of low-velocity impact of a spherical indenter on sandwich panels were deduced. Results show that a hemispherical residual dent caused by bending of top face-sheet and core crushing is left on top face-sheet after impact. It also concludes that more than 80% of impact energy is absorbed mostly by top face-sheet and honeycomb core. The main form of energy dissipation is plastic dissipation. In addition, parametric studies were carried out to explore effects of impact energy on impact behavior by altering impact velocity or impactor mass. Different effects are observed for the two approaches and some useful semi-empirical formulations based on both experimental and numerical results are overfitted to estimate the residual dent depth and energy absorbed during a drop-weight impact event on a honeycomb sandwich panel under a spherical impactor.