STUDY ON DUCTILE FRACTURE OF Q460C HIGH-STRENGTH STRUCTURAL STEEL BASED ON MMC FRACTURE MODEL

In order to study the ductile fracture behavior of Q460C high-strength structural steel, ductile fracture tests under monotonic loading were carried out on nine specimens with different stress states. The full-range true stress-true strain curve of Q460C steel until fracture was obtained by the modified weighted average (MWA) method, and the material parameters of the void growth model (VGM) and the Modified Mohr-Coulomb (MMC) fracture model were calibrated by MATLAB optimization code. The fracture simulation for each specimen was implemented in ABAQUS/Explicit solver with the help of the VUMAT subroutine, and the relative prediction accuracy of the two models for each specimen was assessed. Finally, the generalizability of the MMC model parameters calibrated to fracture prediction of Q460 steel was verified by fracture simulations of two existing notched round bar tests. The results demonstrate that the load-displacement responses obtained from numerical simulations using the MMC model are in a good agreement with the experimental ones, especially for pure shear and shear-tension specimens. The MMC model with stress softening can accurately and visually predict the fracture initiation and propagation of each specimen. The parameters of the MMC fracture model calibrated have relatively good applicability for predicting the fracture behavior of Q460 steel. © 2024 Tsinghua University. All rights reserved.