J-integral evaluation of single-edge notched specimens under mixed-mode I/II loading

Standard test methods of mixed-mode fracture toughness still do not exist, even though a decrease of fracture toughness with increasing Mode II (shear components) has been observed for a number of steels. A J-estimation schem e for mixed-mode loaded single-edge notched specimens is therefore develope d in this paper. In accordance with the ASTM Standard E 1820-99, the evalua tion of the plastic part of J is based on the measurement of the dissipated plastic energy weighted by a eta (pl)-factor. Two different approaches for the eta (pl)-factor are derived. Factors from both showed good correlation with finite element calculations for the specific case of a compact-tensio n-shear specimen (C(TS)). Finally, a simple clip gage setup for the measure ment of the crack-opening displacements needed for the evaluation of the di ssipated plastic energy is presented. The problem of the qualification of t he mixed-mode crack initiation data is not specifically addressed, but some general comments on this topic are given at the end of the paper.