A crack length control scheme for solving nonlinear finite element equations in stable and unstable delamination propagation analysis

An automatic incremental solution algorithm for nonlinear static finite element analysis of delamination propagation problems is presented. This load–displacement–constraint method iterates in the load displacement space utilizing the Newton–Raphson method, allowing to trace out the complete equilibrium path. The procedure can calculate pre- and post-critical responses of bi-dimensional problems, ranging from stable delamination growth to structural collapse by unstable growth or delamination buckling with arbitrarily sharp snap-back instabilities. Benchmark solution examples of established composite materials structural problems illustrate the effectiveness of the method.