Low-velocity impact of honeycomb sandwich composite plates

The performances of low-velocity impact (LVI) and compression after impact (CAI) of honeycomb sandwich composite panels are investigated experimentally and numerically. Honeycomb sandwich panels with different facesheet thicknesses are impacted by drop-weight machine under gradually increasing impact energies. The visible surface damage is recorded and ultrasonic C-scan technology is used to inspect the internal damage of sandwich plates. Numerical simulation is conducted using finite element method, taking into account both facesheet damage and honeycomb damage. The facesheet damage model is based on the continuum damage mechanics and cohesive zone model to simulate intralaminar and interlaminar damage respectively. The honeycomb damage model, which takes into account of both compressive damage and shear damage, is addressed and verified by three-point bending experimental tests. The numerical results show good agreements on LVI and CAI with the experiments, thus verifying the validity of the presented numerical model. Then we use the numerical model to simulate the LVI properties of sandwich plates under compressive and tensile preloading. We conclude that the interlaminar delamination damage of facesheet easily evolves under compressive preloading while intralaminar fiber fracture damage could expand under tensile preloading. The conclusion in our article could be useful to the design and analysis of composite sandwich structures.