切欠部に発生した疲労き裂のJ積分範囲の簡便評価

抄録

In a previous paper, the present authors discussed the path-integral expression of the J-integral range, ΔJ, for short fatigue cracks emanating from notches, and showed that ΔJ evaluated based on the crack-opening level was an appropriate parameter for characterizing the near-tip stress and strain fields. In this study, finite-element simulations of fatigue crack growth from notches were conducted. The ΔJ-values evaluated by the path-integral were compared with those estimated by El Haddad's simple estimating formula proposed for short fatigue cracks at notches, and with those estimated by Dowling's formula and by Cho's formula proposed for deep cracks. The ΔJ evaluated by El Haddad's formula did not agree well with ΔJ values evaluated by the path-integral. On the contrary, ΔJ values evaluated by Dowling's formula based on the crack opening level agreed well with ΔJ values evaluated by the path-integral.