Mode III Delamination in FRP Laminates with Elastic Couplings

Carbon fiber reinforced polymer (CFRP) laminates are widely used in many engineering applications. Nevertheless, composite laminates are susceptible to delamination which can follow according to three fracture schemes. The need for better recognition of determination the mode III fracture toughness became a swollen problem in the face of lack of commonly accepted standard. Determination of the pure mode III fracture toughness by using existing test configurations, such as the ECT or the family of the SCB approaches is not possible due to presence of contribution of different modes, in particular near free specimen edges. Results of research conducted on elastically coupled laminates revealed, that edge effects were dependent on applied boundary conditions. This suggested, to analyze influence of different boundary conditions in case of the anti-plane shear SCB tests, in such way, to find configuration that would minimalize an edge effects and allow to obtain pure mode III circumstances.