Analysis of Test Specimens for Interlaminar Mode II Fracture Toughness, Part 2. Effects of Adhesive Layers and Material Nonlinearities

Approximate and exact elastic stress analyses are reported for end-notched flexure tests for mode II fracture toughness specimens made of composite laminates with adhesive interlayers. Based on the results approximate expressions are given for data analysis by fitting compliance versus delamination length data or for direct computation of energy release rates. Effects of elastoplastic interlaminar shear response or sub-critical microcracking type interlaminar damage are also studied. Sizes of plastic or damage zones are estimated which will be useful for choosing specimen dimensions.