拘束効果を考慮した極低サイクル疲労下におけるき裂進展条件クライテリオンの提案

CTおよび中央貫通切欠き試験片による評価

抄録

The prediction of fracture behavior under extremely low cycle fatigue due to excessive loading is necessary for the life assessment of structures. ΔJ criterion has been used to assess the life under low cycle fatigue. However, the applicability of this method is not well confirmed under extremely low cycle fatigue. The reason is that fracture toughness is dependent on the loading conditions and geometry due to the constraint effect. In the previous study, the crack propagation criterion was proposed for a 1T-CT specimen of SUS316, focusing on the stress triaxiality and the equivalent plastic strain increment. However, no comparison has been performed for specimens of different shapes or materials, and more detailed verification is required. In this study, we performed generation phase and application phase analyses on 1.5T-CT and MT specimens. The results of both the generation and application phase simulation are in good agreement with the experimental results.