Simple Fatigue Crack Propagation Evaluation by Enhanced Reference Stress Method Using Open-Source CAE

Abstract

AbstractAlthough J-integral type fracture mechanics parameters are effective for estimating crack propagation behaviors under elastic–plastic situations such as low-cycle fatigue, calculation of J-integral type non-linear fracture mechanics is still time-consuming and laboring. Instead of costly inelastic FEA of cracked components, the enhanced reference stress method can be used in estimating elastic–plastic J-integral from stress intensity factors and limit load solutions. The solution of limit loads and limit load correction factors (database) required to use this method is limited to some simple representative component geometries. This study aims to improve the usability of the reference stress method by creating database using open-source CAE (Salome-Meca, code_aster, ver. 2018) to obtain solutions of stress intensity factors and other necessary solutions such as limit load correction factors. The solutions obtained were compared with commercial CAE (Marc, Mentat, ver. 2019) and the fully plastic solutions by Ueda and Yagawa. Finally, fatigue crack propagation was calculated using the elastic–plastic J-integral obtained using the simplified methods of a pure elastic method, the fully plastic solution approach, the original reference stress method, and the enhanced reference stress method. In addition, the results of the simplified methods were compared with the results of the fatigue crack growth experiment under fatigue load previously conducted by Fukuda and Satou, and then the effectiveness of the correction coefficients obtained in this study has been verified. In addition, automatic modeling of cracked geometry was employed with a Python script that saves labor to construct FEA models for the fracture mechanics parameter database effectively.KeywordsCrack propagationFatigueOpen SourceInelastic J-integral