Experimental and numerical study of delamination caused by local buckling of thermoplastic and thermoset composites

Abstract Experimental and numerical studies of delamination caused by local buckling have been carried out on thermoset and thermoplastic carbon-fibre composites. The propagation of delamination appears only after the appearance of macrocracks in the buckling plies. In the first part of this work, acoustic emission (Felicity ratio) is used to qualify damage accumulation before propagation of delamination. The second part deals with the determination of the initiation of delamination by two numerical methods, the first of which allows us to calculate the global restitution energy rate (virtual crackextension method) and the second its partition into modes I, II and III (modified crack-closure integral). A mechanical failure criterion is then applied to a stacking sequence and two materials. This criterion is compared with an interfacial stresses criterion determined by the finite-element method.