Fragmentation of composite material plates submitted to impact loading: Comparison between numerical and experimental results

Composite structures absorb energy during crash via fragmentation. This differs substantially from metallic structures where energy is absorbed by large plastic deformations developed during structural collapse. Fragmentation occurs locally by means of different simultaneous and complementary mechanisms related to the non-homogeneous nature of the composite material. Matrix failures under both traction and compression, and fibres failure in traction may occur in the material that constitutes each single lamina. Moreover in a composite material plate consisting of more than one lamina, laminate failure occurs when they all fail at some location, so that material can no longer carry the external loads at this location. The aim of the proposed paper is to compare the results obtained applying a computational methodology, based on the finite element technique, with experimental results analysing the behaviour of composite material plates subjected to impact loading. The paper briefly reviews the basic specific features of the computer code that was developed and implemented by our research group on the basis of the well known DYNA3D explicit finite element code. In particular the mechanical model adopted to describe the progressive damage of a composite material, is briefly presented with particular emphasis on lamina strength, both before and after failure, when its mechanical properties partially or totally degrade.