2019 年 37 巻 3 号 p. 115-124
The aim of this study is to confirm that ductile crack growth resistance of cracked components can be predicted by simulation model with the proposed damage model, which is derived by unit cell analyses with an initial void and reflects void growth behavior until ductile crack initiation. Critical strain under constant stress triaxiality history, which is used in the damage model as ductility of the material, could be determined properly using tensile test results by inverse analyses. Tensile tests using notched round bar specimens, which simply represent stress triaxiality history similar to cracked component, were conducted for two different steels and the proposed damage model was found to be validated for evaluation of ductile crack initiation limit. Then, ductile crack growth tests of two types of bend specimens with a machined notch and a fatigue pre-crack were conducted for a mild steel. It was demonstrated that ductile crack growth resistance could be reproduced using simulation model with the proposed damage model with high accuracy and the influence of plastic constraint to ductile crack growth behavior could be simulated.