Analytical solutions for modelling delamination of composite laminates: from elastic interface models to discontinuous cohesive laws

Delamination is a major failure mode for composite laminates. A huge number of analytical, numerical, and experimental studies have been devoted to this topic during the last decades. The seminar presents an overview of developments carried out at the University of Pisa in the last 15 years. Analytical solutions have been determined for a number of application problems, including: buckling-driven delamination under static and fatigue loads, debonding of adhesive joints and FRP reinforcements, modelling of delamination toughness tests (DCB, ENF, MMB, DCB-UBM, etc.). In the earliest (and simplest) models, an elastic-brittle interface is considered between the separating layers; later on, piece-wise linear cohesive laws have been considered, e.g. for modelling FRP debonding; recently, discontinuous cohesive laws, i.e. with different types of behaviour in the undamaged/elastic and damaged/fracturing stages, have been proposed. In this last case, the J integral has proven to be an effective tool to easily determine analytical solutions without solving complicated differential problems