疲労き裂伝ぱの数値シミュレーションによるJ積分範囲ΔJの簡便評価に関する検討

概要

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In a previous paper, the present authors discussed the path-integral expressions of the J-integral range, ΔJ, and showed that ΔJ-values evaluated based on the crack-opening level was the most appropriate parameter for characterizing the near-tip stress and strain fields under elastic-plastic fatigue conditions. In this paper, finite element simulations of fatigue crack growth in a plate subjected to tension are conducted, to compare the ΔJ-values evaluated by the path-integral with those estimated from load-point displacement by the Dowling's formula, which is commonly used for the laboratory ΔJ-determination. When the crack-opening level is selected as a reference level, ΔJ-values evaluated by using the load-point displacement are found to agree well with those evaluated by the path-integral, and to correlate well with crack-tip opening displacement, for deep cracks but not for shallow cracks. When crack-center opening displacement is used in place of the load-point displacement, a reasonable estimation of ΔJ can be made even for shallow cracks.
1989-01-25