基于MMC模型的Q460C高强结构钢延性断裂性能研究

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

  • 摘要: 为研究Q460C高强结构钢的延性断裂性能,对处于不同应力状态的9个试件进行了单调加载断裂试验。采用修正加权平均(MWA)法获得了Q460C钢材直至断裂的全过程真实应力-真实应变曲线,通过编写MATLAB优化程序校准了VGM和MMC断裂预测模型的参数。借助VUMAT子程序将相关参数代入ABAQUS/Explicit求解器模拟各试件的断裂行为,评估了两种断裂模型对各试件断裂预测的相对精度。通过对已有文献中两个圆周缺口试件的断裂模拟,验证了该文校准的MMC模型参数对Q460钢断裂预测的普适性。研究结果表明:采用MMC模型进行数值模拟得到的荷载-位移响应与试验结果吻合度较好,尤其是对纯剪和剪拉试件的断裂模拟;带应力软化的MMC模型可准确且形象地再现各试件的起裂和裂缝扩展;该文校准的MMC断裂模型参数对Q460钢材断裂行为预测具有相对较好的适用性。

     

    Abstract: 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.

     

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