SHEAR-DRIVEN DELAMINATION PROPAGATION IN 2 DIMENSIONS

This paper investigates, theoretically and experimentally, the propaga tion of delamination in shear mode II between internal ply surfaces in a laminated composite plate. By considering two special cases the pro blem is approximated as an axisymmetric model amenable to analytical s olutions. In one case the circular crack front expands and in the othe r it contracts. It is shown clearly that only a (linear) fracture mech anics approach will explain the mode and threshold of failure, but tha t a strength-based criterion can be used to initiate propagation witho ut the need for an initial flaw. Apart from explaining some curious ph enomena, the simple axisymmetric analytical solutions may be used as b enchmarks for testing the ability of finite element models to predict plate delamination when the crack front is curved (at present only sim ple beam models are available for the standard DCB and ENF tests, but even these tests do not really develop straight crack fronts). (C) 199 7 Published by Elsevier Science Limited.