Failure assessment of fiber metal laminates based on metal layer dispersion under dynamic loading scenario

In this study, tensile behavior of Glass Fiber Reinforced Polymer (GFRP) sandwiched with different thickness aluminium alloy layers were investigated at strain rates of the order 400–480 /s. The loading was induced through Spilt Hopkinson Tensile Bar (SHTB) setup and specimen size and shape were determined through Finite Element (FE) analysis by ensuring all damage modes should evolve inside the gauge region of the specimen. Three GLAss fiber REinforced (GLARE) aluminium laminates with top/bottom metal layers apart from the inside layer(s) were investigated. The idea is to observe the dynamic response of these laminates when they are sandwiched with no metal layer, one metal layer and two metal layers inside their lay-up configuration. They were named as 2/1–0.6, 3/2–0.4 and 4/3–0.2(O) laminates respectively. The FE analysis is used to observe the damages occurred within these laminates which are later compared with the experimental results. However, FE analysis results were able to investigate in-depth damage and failure occurring in these laminates unlike in experiments. Johnson-Cook (J-C) damage model was used as a material model for metal layer modeling while for GFRP a strain rate dependent 3D Hashin damage user-defined model is incorporated via VUMAT to observe the failure occur in these laminates. The interface delamination between the laminas were invoked through cohesive surface methodology. The GLARE laminates with metal layer(s) inside the configuration i.e. 3/2–0.4 and 4/3–0.2(O) laminates, was found to have comparable strength with GLARE having no metal layer inside the layup i.e. 2/1–0.6 laminate. From FE analysis it was noticed that the initiation of delamination due to the formation of matrix cracks in quasi-static loading was delayed in high strain rate loading as the strength in the matrix failure mode was higher due to rate sensitivity. However, the sequence of failure events occurring in these laminates like metal yielding, matrix failure, fiber failure accompanied with delamination remains same as in quasi-static loading.