Modelling interlaminar and intralaminar damage in filament wound pipes under quasi-static indentation

A pragmatic model is proposed to predict interlaminar and intralaminar damage, i.e., delamination and matrix cracking, in filament wound pipes. The pipe is modelled as an assembly of sublaminates connected along their interfaces. The initiation of delamination and transverse matrix cracking is predicted based on stress-based failure criterion. Delamination propagation is governed by the energy release rates. After the occurrence of damage, constraint between sublaminates is removed to model the delamination and a ply discount model is used to account for the material degradation effects of matrix cracking. The establishment of a leakage path is comprised by jointed matrix cracking in each layer and delamination at each interface. Finite element analysis has been carried out to simulate the quasi-static indentation of filament-wound composite pipes. Despite the simplification of treating each damage mechanism independently (i.e., no direct interactions), good agreement has been achieved between experimental results and the predictions of the model for the load-indentation relationship, the evolution of multiple delaminations and the formation of a leakage path.