Matrix Cracking Effect on Delamination Growth in Composite Laminates Induced by a Spherical Indenter

Abstract

An investigation was performed to study the mechanics of delamination growth in fiber-reinforced laminated composites resulting from transverse concentrated loads. The effect of matrix cracking on delamination propagation was the primary focus of the study. For simplicity's sake, only cross-ply laminates were investigated. An analytical model was proposed for determining the response of the laminates containing a matrix crack-induced delamination and subjected to a concentrated load through a spherical indenter. Two types of matrix cracks were considered in the model: a surfacebending crack and an internal shear crack. The model consists of three parts: a stress analysis, a contact analysis, and a failure analysis. A nonlinear three-dimensional finite element model based on an updated Lagrange formulation was developed for calculating stresses and strains in composites. An augmented Lagrangian method was utilized to simulate the interfacial contact condition of the embedded delamination and the indentation between the composite and the indenter. Fracture mechanics was applied to predict the delamination growth in three dimensions. In order to verify the model, results of the calculations from the analysis were compared with the existing solutions and test data available in the literature. Experiments were also conducted to further substantiate the model and the predictions from the analysis. Overall, the predictions agreed well with the existing solutions and the test data.