Verification of Simplified J-Integral Evaluation Method for Flaw Evaluation at High Temperature
T,Shimakawa, N.Miura, Y.Nakayama and Y.Takahashi
Abstract:J-integral is the feasible parameter to represent fracture behavior in non-linear regime. However there are many difficulties to calculate accurate J-integral in actual components. CRIEPI has been developing a simplified J-evaluation method based on the reference stress approach . This paper presents verifications of the proposed method through three representative parameters. The first subject is the creep-fatigue crack propagation problem of test specimens such as CT and CCP. Calculated results are compared with those measured in experiments. Applicability to creep-fatigue problem is verified through this comparison. The second subject is the creep-fatigue crack growth problem of a plate with semi-elliptical surface crack. Estimated fatigue J-integral and creep J-integral are compared with finite element analysis results. Applicability to the surface crack problem is confirmed. The third subject is the creep-fatigue crack growth problem of a cylinder under thermal stress. Applicability to thermal stress is also verified. These results show that J-integral values calculated by the proposed method coincides with experimental and finite element analysis results. It is confirmed that the proposed method is applicable for the flaw evaluation of cracked components at high temperature. Key Words:Flaw evaluation, FBR, Creep-fatigue, Crack propagation, J-integral, Simplified analysis, Reference stress