考虑罗德角参数的钢材薄板延性断裂标定方法

在钢结构中钢梁腹板的断裂表现出很强的剪切断裂特征，因此在预测其断裂行为时除了考虑应力三轴度以外，还应考虑与剪切状态有关的罗德角参数的影响。该文提出了一种适用于钢材薄板延性断裂预测的标定方法。共设计了5组试件，分别为平板试件、开孔平板、开槽平板、90°剪切平板和45°剪切平板。利用平板试件和停机平板试件单向拉伸试验，结合有限元反演得到钢材的全过程真实应力-应变曲线。然后将其代入各试件有限元模型进行计算，标定出各试件对应的等效断裂应变、平均应力三轴度和平均罗德角参数。最后利用Matlab优化工具箱对断裂模型进行优化拟合，确定模型中的各项待定参数。

DUCTILE FRACTURE LOCUS VALIDATION METHOD OF THIN STEEL PLATES CONSIDERING THE LODE ANGLE PARAMETER

It was observed that shear fracture dominates in the fracture of steel beam webs. For this reason, the lode angle parameter should be taken into account along with the stress triaxiality. A new ductile fracture calibration method applicable to thin steel plates is proposed in this paper. Five groups of specimens were designed in this paper. They are flat plates, holed flat plates, flat grooved plates, 90° shear plates and 45° shear plates. The true stress-ture strain (-) curves were obtained through flat plate, halted flat plate specimens and relevant finite element (FE) method iterations. The FE models of other specimens were computed with this σ-ε relationship and compared with related experimental results to obtain the corresponding equivalent fracture strain, average stress triaxiality and average lode angle parameter. With the help of the Matlab Optimization Toolbox, the optimal parameters of the fracture model can be determined.