Design and modelling of auxetic double arrowhead honeycomb core sandwich panels for performance improvement under air blast loading

In the present study, a 2D-based large-scale metallic auxetic double arrowhead honeycomb core sandwich panel (DAHSP) was proposed and its deformation response, energy dissipation characteristics and associated mechanisms under air blasts were investigated using a validated numerical model. It aims at the performance improvement of DAHSPs through the design of core relative density with respect to different strategies. The DAHSPs considered mainly experienced a local dome superimposed upon global deformation of front face and global deformation of back face, while the core webs were heavily buckled and progressively collapsed. The results confirmed the material concentration effect of DAH cores induced by the negative Poisson’s ratio (NPR). It was found that the panel deformation response was highly related to their deformation/failure mechanisms. Relative to core web thickness, the increase of number of core layers led to a more remarkable decrease in permanent deflections. However, the decline of inclined angles not always reduced the back face deflection due to the competition between enhanced bending stiffness and deteriorated local contact force. An ideal means to decrease the panel deformation is to enlarge the inclined angles at low relative density but to decrease the horizontal distance when the relative density increases to a high level. The panel with thinner core webs at low relative density and the panel with narrowed inclined angles at high relative density is more beneficial to plastic energy absorption. In addition, a core configuration with a thinner tendon but a thicker stuffer promoted the exploitation of NPR and further improved the panel energy absorption.