SA-07-4(027) Simplified Estimation Method of Inelastic J-integral for Creep-Fatigue Crack Propagation Prediction in General Loading Conditions(Flaw Assessment at Elevated Temperature 2)

概要

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In predicting the propagation behavior of a crack-like defect under creep-fatigue loading, use of a J-integral type fracture mechanics parameter, the elastic-plastic J-integral, J, in elastic-plastic situations or the creep J-integral, C (t), in creeping situations, has been found to be effective from previous experimental work. This paper proposes simplified methods to estimate J and C (t) for crack propagation life assessment of a high temperature component subjected to general creep-fatigue loading conditions. The proposals are based on the reference stress approach for mechanical loading, and the Neuber's rule type method for strain-controlled thermal stresses. These methods already have been incorporated into the British defect assessment procedures, R5 and R6. The author has been involved in additional developments of and making modifications to these methodologies for the purpose of improving their practicality. This paper reviews those relevant activities in light of the applicability of the simplified methods to practical conditions, and proposes some modifications for treating complex loading, e. g., displacement-controlled loading with elastic follow-up, together with some supporting numerical examples.
一般社団法人日本機械学会の論文
2001-06-03