The low velocity impact response of sandwich panels with lattice core reinforcement

•Lattice core sandwich structures were formed using a self-propagating photopolymer waveguide process.•The sandwich structures were subjected to low-velocity impact testing with four different impact energy magnitudes.•A homogenized constitutive model was developed to simulate lattice deformation and failure under dynamic loading.•At all impact energy levels, excellent correlation was observed between the impact measurements and simulations.

This study presents the experimental and simulation results for the low velocity impact response of sandwich panels reinforced with a lattice core structure. Two different core material and architecture combinations are investigated; a UV-cured photopolymer lattice, produced from a network of self-propagating waveguides, and an aluminum alloy lattice cast from an initial polymer template. For each of these sandwich panel configurations, impact tests were performed with a drop-weight hemispherical impactor under four different energy levels. The applied impact force, impactor velocity and residual damage in the sandwich panel were all measured and used for comparison against finite element simulations of the impact tests. These simulations employed a homogenized continuum constitutive model, designed to replicate the deformation response of the lattice core without requiring explicit representation of the geometric features of the lattice. For both sandwich panel designs at all impact energy levels, excellent correlation was observed between the experimental measurements and impact simulations. Additionally, each sandwich design was shown to be effective at absorbing the kinetic energy of the impactor with minimal damage to the back (non-impacted) face of the panel. Implementation of these lattice core sandwich panels and extension of the homogenized constitutive model to other sandwich applications are also discussed.