Prediction of delamination onset and growth for AP-PLY composite laminates using the finite element method

A recently developed fibre placement architecture, Advanced Placed Ply (AP-PLY), has been shown to have promising damage tolerance characteristics for composite structures. Understanding delamination creation and growth in such architecture is of particular concern. Approaches to predict delamination onset in AP-PLY architectures and to analyse delamination growth are presented. The recovered interlaminar stresses between layers combined with a maximum stress criterion were used to determine delamination onset of simple AP-PLY composite laminates under out-of-plane loads. 2D finite element models with cohesive elements inserted at the interfaces of woven layers were used to evaluate the delamination initiation and propagation in different woven patterns of simple AP-PLY composite beams. The predictions were compared to results from the stress recovery method and to test results. The parameters of the woven pattern, such as woven angle, number of woven plies, number of straight filling plies, and the location of the woven patterns through the thickness direction, were investigated and shown to have a significant effect on delamination creation and growth.