Imperfect interlaminar interfaces in laminated composites: interlaminar stresses and strain-energy release rates

A numerical procedure with interface finite elements has been carried out in order to investigate the influence of imperfect interlaminar interfaces on the local mechanical behaviour of composite laminates. By modelling laminates at a mesoscopic scale, interlaminar interfaces are clearly represented and the effects of interfacial imperfections are thus characterised by displacement discontinuities across each interface. Emphasis is placed on assessing implications of weakened interfaces for the distribution of interlaminar stresses and the change in strain-energy release rates.