Damage sensitivity studies of composite honeycomb sandwich structures under in-plane compression and 4-point bending: Experiments and numerical simulations

Honeycomb sandwich structures, especially those with carbon-fiber panels and Nomex-honeycomb cores, are widely employed in automobiles and aircraft due to their excellent mechanical properties. Here, in-plane compression and 4-point bending experiments, as well as FEM simulations, are performed for a composite honeycomb sandwich structure with face-core de-bonding defects or impact damage to evaluate the damage sensitivity. It is found that the structure exhibits a higher sensitivity to impact damage than to de-bonding defects. Impact damage caused by an energy of 3 J-5.5 J can alter the failure mode under both in-plane compression and 4-point bending loads, and reduce in-plane compression strength by more than 50 % and 4point bending strength by 15 %. In comparison, de-bonding defects of the same size can change the failure mode and decrease the strength by only 10 % under in-plane compression. The developed FEM model predicts all failure modes and residual strengths obtained from experiments. The simulation results show that the structural characteristics of producing concaves in the facesheet and core are the dominant contributors to structural failure. Our model, covering all geometric and structural details of the honeycomb core, provides a useful tool for studying the mechanical behaviors of such structures.

Automated summary

In this study, the damage sensitivity of a composite honeycomb sandwich structure with face-core de-bonding defects or impact damage was evaluated through in-plane compression, 4-point bending experiments, and FEM simulations. It was found that the structure is more sensitive to impact damage than to de-bonding defects. Impact damage with an energy range of 3 J-5.5 J can significantly change the failure mode and reduce the strength of the structure, while de-bonding defects of the same size only cause a minor decrease in strength. The developed FEM model accurately predicts the failure modes and residual strengths observed in experiments, indicating that the structural characteristics during impact loading are the main contributors to structural failure. Our model provides a useful tool for studying the mechanical behaviors of honeycomb sandwich structures.