Interlaminar fracture behaviour of laminated composites

The interlaminar fracture behavior of composite laminate under full range of in-plane loading conditions has been investigated. Loading conditions from pure mode I through various mixed mode I/II ratios up to pure mode II have been generated by the aid of the proposed compound version of the compact tension shear specimen. From the experimentally measured critical loads the mode I, mode II and the various mixed mode I/II critical energy release rates at crack initiation have been determined by the aid of the finite element method and the modified virtual crack closure integral method. Based on these results the parameters for a fracture criterion for the composite under consideration have been determined.