Proposal of Crack Propagation Criterion Considered Constraint Effect under Extremely Low Cycle Fatigue; Evaluation by 1T-CT and 2T-CT Specimen

. The strength evaluation of structures that requires high reliability, such as power generation facilities, is extremely important. It is necessary to ensure safety under extremely low cycle fatigue caused by earthquakes. However, a highly reliable evaluation method has not yet been developed because of variable fracture toughness due to the constraint effect with large deformation. The crack propagation criterion proposed by the previous study has needed some modification for accurate prediction. In this study, we confirmed whether the crack propagation criterion proposed by previous study can reproduce the fracture behavior of the experiment. Among then, relationship between the number of cycle and crack length, hysteresis loop, reproduction of crack shape were evaluation items.