Fatigue-driven model for mode II interlaminar delamination propagation of fibre/epoxy-reinforced composite laminates under three-point end-notched flexure

This paper deals with mode II interlaminar delamination properties and failure mechanisms of composite laminates in three-point end-notched flexure (3-ENF) tests under fixed cyclic loading. The results for fracture toughness, fatigue driving force and delamination propagation behaviours of three different types of carbon and E-glass fibre/epoxy resin-reinforced composite laminates are evaluated and compared with each other for providing an insight into fatigue damage development in composites and for constituting a fundamental basis for the development of a characterization model. A new characterization formulation is presented for mode II interlaminar delamination propagation based on controlling fatigue stress. Finally, the model is applied to experimental data, demonstrating the practical and effective use of the proposed model. It is shown that fatigue-driven strength for mode II interlaminar delamination propagation can be obtained realistically from experimental data using the new formulae.