Simulation of impacts on plates made of composite material

Abstract

The paper describes in some detail the difficulties encountered when conducting simulations intended to be realistic, and hence useful from a predictive viewpoint, of localised impact events on composite shells.Experimental results of drop tower tests were available on this occasion, consisting of an impactor with semi-spherical end being dropped from various heights onto a square shell made of composite material.The exhaustive simulations performed included different constitutive behaviours of the material, damage models, element types, and simulation strategies (three-dimensional and axially symmetric).The results show that, as the damage level increases, the problem becomes very complex because it requires capturing well the onset of interlaminar failures, as well as reproducing accurately the transition from a bending to a membrane resisting mechanism, which is what happens as those failures accumulate. The best results were obtained using very refined meshes, with four levels of elements per layer, and with cohesive elements between adjacent layers.Apart from the difficulties posed by the numerical simulation, it is worth pointing out that the study of these problems also tends to suffer because the characterisation of the parameters and properties governing the material behaviour is often less precise and reliable than desirable.