Experimental, analytical, and numerical analysis of perforation behavior of a novel hybrid composite sandwich panel

This paper investigates the phenomenon of high-velocity impact on a lightweight composite sandwich panel comprising of autoclaved aerated concrete (AAC) core and fiber metal laminate (FML) face skins. These experimental trials were explicitly designed to ascertain the ballistic limit velocity (BLV) of FML reinforced AAC subjecting to impact loading of a rigid flat-nosed projectile. In conjunction with experimental investigations, an analytical model based on closed-form solutions employing energy equations was meticulously developed to offer a deeper analysis of the impact event. This analysis encompassed the identification of various damage mechanisms that manifest during high-velocity impacts, including core crushing, tensile fracture, fiber breakage, delamination, plugging and the formation of petals. Furthermore, a sensitivity analysis using dimensionless variables was employed to provide a more profound insight into the influence of diverse parameters such as the mass and initial velocity of the projectile. Additionally, three-dimensional finite element method (3D FEM) simulations via the Ls-Dyna package were carried out to estimate the effects of various projectile nose shapes on ballistic performance, failure modes, energy absorption (EA), and specific energy absorption (SEA) of the target. The simulations revealed that the projectile nose shape can induce various damage mechanisms within the FMLRAAC panel. During the impact process, the E glass/epoxy composite layer undergo matrix cracking, fiber breakage occurred along with delamination, and consequently, the Al skin underwent plastic deformations until this layer fractured permanently at the impact position. As a result insulating AAC in a sandwich structure between two FML face skins reproduce a significant strength and stability. Moreover, the manufacturing of FMLRAAC in construction is a simple process to promote its structural capability especially for hazardous environment as load bearing structural material.