A general approach for the study of kink band broadening in fibre composites and layered materials

The progressive non-linear mode of deformation known as steady-state kink band broadening is analysed for fibre composites and layered materials. The mode of deformation is investigated using an analytical, a semi-analytical model and a finite-element model. The semi-analytical model is based on a constitutive model, where independent material behaviour can be given for two constituents. The analytical model assumes rigid fibres and results in a transcendental equation for the kink band broadening state. Both the analytical and semi-analytical model use a Maxwell construction to determine the steady-state, which is done by equating the internal and external work. The influence of size-effects are explored and two case studies are performed; in the first case study the finite element model and semi-analytical model are used upon a carbon fibre-reinforced PEEK composite. The second case study is on a layered composite made from ultra high molecular-weight polyethylene fibres with a kink band developing on ply level.