On the numerical treatment of the delamination problem in laminated composites under cleavage loading

A method for the effective numerical treatment of the delamination problem in laminated composites under cleavage loading is herein proposed. The interlaminar interface mechanical behaviour is described by means of the so-called complete laws which are non-monotone and possibly multivalued force/ displacement laws including jumps (or in general, decreasing branches) corresponding to the discontinuous strength reduction. These complete laws that take into account the development of delamination phenomena in a quasistatic way are derived by non-convex energy functions, called delamination superpotentials which in turn, lead to the formulation of the principle of virtual work for the laminated composite in a hemivariational inequality form and to the generalisation of the principle of minimum potential energy as a substationarity principle. Applying an appropriate finite element discretisation scheme to the laminated composite, the respective discrete problem is formulated which describes the response of the structure taking into account the development of the delamination phenomenon. The numerical treatment of the latter problem is successfully performed by applying a new algorithm that approximates the nonmonotone law by a sequence of monotone ones. The performed numerical applications presented in the last part of the paper and several analogous numerical experiments exhibit very good convergence properties.