Simulation and experimental investigation of impact damage in composite plates with holes

A number of authors have carried out finite element simulations of the damage produced in fibre composite laminates by medium and high velocity impacts, with results which generally show good agreement with experimental evidence. In some engineering applications, these laminates may be constructed with pre-existing holes or cut-outs whose presence may significantly affect the nature of the impact damage. As far as is known, no study of this problem has appeared in the literature and this paper reports the first results of an experimental and simulation exercise to determine the additional damage arising from the presence of holes. The experimental evidence shows that the holes can induce matrix cracking in the lower lamina which is additional to that arising in the laminate without holes. These matrix cracks can extend from the region directly below the impact to the edge of the holes and in some circumstances further cracks can emanate from the far side of the holes. The simulation predicts that the presence of the holes can give rise to multiple cracks directly below the impact region which spread towards but not up to the holes, together with a crack emanating from the hole towards the impact region. Thus, whilst the computations are in qualitative agreement with the experimental evidence there is a need for further work in order to improve on the predictions.