Effect of Cell Geometry on the Out of Plane Response of Aluminium Honeycomb Using Finite Element Method

Abstract

Two-dimensional cellular structures – honeycombs are known to exhibit high compressive strength and energy absorption in out of plane compressive loading. The energy absorption capability of impact crushing of these structures is affected not only by the mechanical properties of the honeycomb but by the geometric structure of the honeycomb cell as well. In present study, a finite element (FE) framework is utilized for the comparison of the peak collapse stress, mean plateau stress, and densification strain for different cell shapes of aluminum honeycomb core under impact loading. Results obtained are correlated with the deformation mechanisms involved with the change in cell shape. Non-linear dynamics software LS-Dyna is used to develop an explicit code framework for the simulation, which is validated using compression test results on a thin-walled hexagonal honeycomb structure of aluminum. The thin-walled core of the honeycomb is modeled as a deformable body with shell elements, while the crosshead is modeled as rigid bodies, which strikes the honeycomb core with a velocity of 5 m/s. The cell shapes which are commonly used in sandwich panels like the regular hexagonal honeycomb-square, triangular, and square are studied for the same cell size. It is observed that the triangular cell shapes are the stiffest, while the hexagonal honeycomb has high energy absorption. Furthermore, the effect of strain rate has also been studied for each cell shape of the honeycomb core.