Mixed-mode fatigue failure criteria for adhesively-bonded pultruded GFRP joints

The behavior of adhesively-bonded pultruded GFRP joints under cyclic loading was experimentally investigated. Three specimen types were examined: double cantilever beam, end load split, and mixed-mode bending specimens for Mode I, Mode II, and mixed-Mode I/II loading conditions respectively. The crack length was determined during the fatigue experiments by a dynamic compliance method for DCB specimens and a video extensometer for ELS and MMB specimens. Fatigue experiments were conducted at constant displacement amplitude. A significant difference was found between the quasi-static strain energy release rates and corresponding fatigue threshold values for all the examined cases. A total fatigue life model was used to simulate the fatigue crack growth curve under each mode-mixity. The experimental results and the analytical models were used to establish fatigue mixed-mode fracture failure criteria that can be used for the prediction of the fatigue behavior of other joint configurations comprising the same adhesive and adherends. (C) 2013 Elsevier Ltd. All rights reserved.