점소성-손상모델 기반 피로균열 진전속도 전산 평가법 개발

In this paper, computational evaluation method for fatigue crack growth rate(FCGR) based on material viscoplastic-damage model is proposed.Viscoplastic-damage model expressing material constitutive behavior of 7% nickel steel is introduced and is implemented into commercial finite element analysis(FEA) code, ABAQUS, as a user defined material subroutine(UMAT) for application in the FEA environments.Verification of developed UMAT and material parameters of material model are carried out by uniaxial tensile test simulations of 7% nickel steel.Moreover, jump-in-cycles procedure and rearrangement of critical damage are employed and also implemented to the ABAQUS UMAT for fatigue damage analysis.Typical FCGR test results such as relationship between crack length and number of cycles and relationship between  and  could be obtained from FCGR test simulation using developed UMAT and these results are compared with experimental results in order to verify of proposed computational method.