NUMERICAL SIMULATION OF ULTRA-LOW CYCLE FATIGUE FRACTURE OF Q355 STEELS BASED ON CYCLIC VOID GROWTH MODEL

The cyclic void growth model (CVGM) is based on micromechanics of fracture and can effectively deal with the ultra-low cycle fatigue (ULCF) fracture of structural steels. Smooth bar specimens were tested under cyclic loading to determine the material constants in the combined hardening model of Q355 steels. Single-edge notched plate specimens were tested under different cyclic loadings. The ULCF lives and the development of the ULCF fracture were obtained for all test specimens. Finite element (FE) models were established for the single-edge notched plate specimens. The ULCF lives of these specimens were predicted by the CVGM based on the results of the FE analysis. By programming a user subroutine, the fractured elements were removed from the FE models to simulate the fracture propagation during the loading. The entire process of the ULCF fracture of each test specimen was numerically simulated. The simulation agreed well with the test results, which verified the applicability of the CVGM to the numerical simulation of the ULCF fracture of structural steels.