応力腐食割れにおける分岐き裂効果の評価

概要

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Better fracture resistance is given by the branched crack than non branched one. That is called the crack branching effect. In this paper, the crack branching effect is investigated analytically and experimentally. Stress intensity factor (SIF) of CT specimens with various branched crack parameters as crack length ratio, branching angle and branched crack length ratio were analyzed. The crack branching effect, the ratio of the SIF of non branched crack to the effective SIF of branched crack was approximated by the polynomial equation using parameters above. The maximum crack branchicg effect, in this study, was obtained when these parameters were minimums. The fracture tests were conducted using specimens with SCC branched cracks to determine the experimental crack branching effect, the ratio of the apparent fracture toughness of SCC specimen to the fracture toughness of the non branched fatigue cracked specimen. The experimental crack branching effects were larger than those obtained analytically. It is recognized that the discrepancy between the crack branching effects determined by the analysis and experiment was attributed to the fact that SCC was three dimensional in shape, whereas the SIF were analyzed by the two dimensional FEM and that the conservative crack branching effect is estimated by the analysis.
1989-05-25