Investigation of mixed mode I/II interlaminar fracture toughness of laminated composites by using a CTS type specimen

The interlaminar fracture behavior of a unidirectionally glass fiber reinfo rced composite under the full range of in-plane loading conditions has been investigated. Loading conditions from pure mode I through various mixed mo de I/II ratios up to pure mode II have been generated by the aid of the pro posed compound version of the CTS (compact tension shear) specimen. From th e experimentally measured critical loads, the mode I, mode II and the vario us mixed mode I/II critical energy release rates at crack initiation have b een determined by the aid of the finite element method and the modified vir tual crack closure integral method, Based on these results the parameters f or a fracture criterion for the composite under consideration have been det ermined. (C) 1998 Elsevier Science Ltd, All rights reserved.