Finite element modelling of fibre metal laminates subjected to low velocity impact

The present contribution is concerned with the study of the mechanical response of Fiber Metal Laminates (FMLs) to low velocity impact (below 10 m/s), of interest in aeronautical engineering. In particular, GLARE and CARALL samples were considered. Reference was made to drop-weight test configuration in accordance to ASTM D7136 standards. Advanced Finite Element Models (FEM) were developed in Abaqus environment, apt to describe the nonlinear dynamic response of the laminate when subjected to low velocity impact, on the basis of the following assumptions: Johnson-Cook phenomenological model was adopted for the Aluminum layers; Hashin failure criterion was assumed for the prepregs reinforced by fibers, differently oriented according to the specific layups, enriched by a suitable fracture energy based evolution law for the damage variables; a cohesive behaviour was considered for the interfaces between contiguous layers, described as elements with either finite or zero thickness. In this scenario delamination represents a major issue, seldom favoured by defective production processes. The distribution of damage, possibly leading to interlaminar failures, was predicted within the tested samples. The information thus provided is expected to integrate visual inspection activities in view of the health assessment of structural elements after impact events.