Mode I fracture of epoxy bonded composite joints: 1. Quasi-static loading

Mode I constant displacement rate tests were conducted on epoxy-bonded CFRP joints at -50, 22 and 90 degreesC. A comparison of experimental compliance and different beam theory approaches indicated that care needs to be taken when applying beam theory approaches across a wide temperature range. Temp erature was seen to influence the mode of fracture which progressed from st able, brittle fracture at low temperatures to slip-stick fracture at room t emperature and finally to stable ductile behaviour at elevated temperatures . This behaviour has been attributed to the dependence of critical strain e nergy release rate on crack velocity for epoxy adhesives and a model for th e fracture behaviour of viscoelastic materials has been used to explain the se results. The critical strain energy release rate was seen to increase wi th temperature and the failure locus transferred from predominantly in the composite substrate to predominantly in the adhesive. (C) 2001 Elsevier Sci ence Ltd. All rights reserved.