Influence of metal/composite interface on the damage behavior and energy absorption mechanisms of FMLs against projectile impact

Abstract

This paper focuses on the interface failure in metal/GFRP laminates on account of the high-velocity impact phenomenon by a hemispherical projectile. The study considers three laminates in which the failure inside the 8-layer 0/90 GFRP laminate is compared with the other two laminates that include metal layers in their layup configuration. The metal layers were placed on the top and bottom on one type of laminates while in the other additional metal layers are placed symmetrically inside the layup as well. They were subjected to high-velocity impact by a hemispherical projectile at different energy levels and the idea is not to perforate the laminate configuration instead to account for the damage incurred in these laminates and the role of metal layers in providing resistance to damage within these laminates. The study utilizes experimental findings and proposes a rate-dependent Finite Element (FE) model consisting of the Hashin-Puck failure scheme for composite and the Johnson-Cook damage model for metal layers. The results of the model satisfactorily agree with their experimental counterparts and provide valuable insight into the damage resistance inside the laminates. It has been observed that the 8-layer GFRP laminate was good in terms of elastic recovery and prevention of propagation of damage inside the laminates only, till the impact energy was lower. For higher impact energy, they show poor damage resistance as the fiber failure is triggered in them. However, laminates with metal layers are shown to protect the laminate by dissipating energy in the delamination of metal/GFRP interface, shear failure of the metal layer, and on account of metal plasticity. The study further shows that the through-thickness compressive stresses were responsible for the failure of laminates and also triggering the delamination in them. A damage energy study was performed to investigate the amount of energy dissipating in various failure modes like delamination, matrix cracking, fiber failure, etc.