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 inthree-point end-notched flexure (3-ENF) tests under fixed cyclic loading. The results for fracture toughness, fatiguedriving force and delamination propagation behaviours of three different types of carbon and E-glass fibre/epoxy resinreinforcedcomposite laminates are evaluated and compared with each other for providing an insight into fatigue damagedevelopment 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 controllingfatigue stress. Finally, the model is applied to experimental data, demonstrating the practical and effective use of theproposed model. It is shown that fatigue-driven strength for mode II interlaminar delamination propagation can beobtained realistically from experimental data using the new formulae