An investigation of optimal auxetic cores in sandwich structures to withstand low-velocity impact loading

Abstract

One of the main issues in designing sandwich structures is selecting an appropriate core with optimal dimensions for the application. This study investigated the impact response of auxetic cores with re-entrant structures when subjected to low-velocity impact (LVI) loading. To this end, an analytical model was developed using high-order nonlinear theory, and the corresponding equations were extracted by applying the Ritz method and subsequently solved using the Runge–Kutta method. The analytical model was developed by replacing the porous auxetic core with an equivalent orthotropic solid layer. The numerical simulation demonstrated that the substituted layer exhibited behaviour similar to that of the original auxetic core. The validation of the analytical and numerical models was performed by fabricating several samples using fused deposition modelling (FDM); then, LVI tests were performed on the samples using a drop-weight apparatus. The comparison of the experimental and analytical results indicated that the proposed nonlinear model accurately predicted the behaviour of the auxetic core when subjected to LVI loading. The effects of the different geometric features – including re-entrant angle, strut thickness, core thickness, and impactor energy – were also examined in the parametric study in an effort to gain an enhanced understanding of the behaviour of the auxetic core.