Influence of internal pressure on the out-of-plane dynamic behavior of circular-celled honeycombs

The out-of-plane dynamic behavior of circular-celled honeycombs is studied by both numerical simulations and theoretical analysis. The influences of the internal pressure, the crushing velocity and the cell-wall thickness on the honeycombs’ deformation modes and mechanical characteristics are investigated. The results show that the honeycomb block without pressure inside collapses in Diamond mode, while the deformation mode turns into Petal mode and then Coin mode with the increase of internal pressure. The critical internal pressure for the transformation between deformation modes increases with the crushing velocity but decreases with the cell-wall thickness. The honeycombs’ plateau stress under Diamond mode is the highest and then decreases with the internal pressure under Petal mode. Once Coin mode appears in the honeycomb, the honeycomb's plateau stress hardly depends on the internal pressure. Besides, it is shown that the honeycombs’ plateau stress increases with both the wall thickness and the crushing velocity. In view of the fact that Coin mode is unique for circular-celled honeycombs with high internal pressure, an analytical model is built to deduce the plateau stress of circular-celled honeycombs deformed with Coin mode. The analytical predictions are in good agreement with the numerical simulation results.