Compressive failure of composite laminates containing multiple delaminations

Delaminations cause a reduction in the compressive strength of a composite material and multiple delaminations cause greater strength reduction than single ones. Since realistic damage such as that resulting from an impact consists of multiple delaminations, it is of interest to understand the mechanism of strength reduction for laminates containing multiple delaminations. In this work, compression testing of glass fibre reinforced plastic specimens containing single and multiple embedded delaminations was carried out. Finite element modelling was used to gain further understanding of the mechanisms of compressive failure. Reasonable agreement between finite element predictions and experimental measurements were found for the whole range of delamination geometries that were tested. It is demonstrated that the maximum reduction in strength for a multiple occurs when the delaminations split the laminate into sub-laminates of similar thickness.