Modeling Low Velocity Impact Response of Carbon Fiber Reinforced Aluminum Laminates (CARALL)

Abstract

Fiber metal laminates (FMLs) have shown great potential in lightweight aerospace applications. Carbon fiber reinforced aluminum laminates (CARALL) is a lightweight system that has received less attention than aramid reinforced aluminum laminates. These FMLs have adhesively bonded layered plies. We have developed CARALL without the use of adhesives. The epoxy resin from the carbon fiber epoxy is used to adhesively bond the aluminum layers. In this study, CARALL laminates having a 3/2 configuration, with Aluminum 5052-H32 as the outer layer were prepared using a vacuum press without using any adhesive film. Primary failure modes observed were cracks in non-impacted aluminum layer, carbon fiber (CFRP) layer fracture and delamination between aluminum and CFRP layers. Finite element modeling was used to predict low velocity impact response of these FMLs by considering Chang–Chang damage criteria for CFRP layers and nonlinear elasto-plasticity along with progressive damage mechanics for aluminum layers. Delamination was modeled by using traction separation law and damage criterion proposed by Benzeggagh–Kenane was used for interface damage evolution. The damage size of CARALL FMLs was characterized using C-scan equipment and compared with the finite element predictions. Numerical simulation was used to predict load–displacement histories, delamination area, absorbed energy, damage morphologies on impacted and non-impacted sides and tensile failures of CFRP layers for impact event at three different energy levels. Predicted impact behavior results match well with experimental results. The threshold impact energy, energy at which perforation failure was induced in all metallic and fiber reinforced layers for these CARRAL laminates was found to be around 31 J.