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考虑剪应变对微孔洞损伤演化的影响,对GTN损伤模型的损伤演化机制进行修正,建立了适用于不同应力三轴度水平的损伤模型。结合隐式应力更新算法和显式有限元计算,采用VUMAT子程序实现了修正GTN模型在有限元软件ABAQUS中的数值计算。通过模拟纯剪切和剪切-拉伸两组试样的损伤演化和断裂行为,验证了修正GTN模型在不同应力三轴度承载条件下的有效性。运用修正GTN损伤模型模拟含边部缺口的带钢在轧制过程中裂纹的萌生和扩展行为,模拟结果与实验相一致,表明该模型可有效地用于带钢缺陷在轧制过程中扩展行为的分析和预测。模拟和实验结果表明,带钢边部缺口在轧制过程中,缺口前沿和后沿均会萌生裂纹,且后沿裂纹扩展更为明显。
Considering the influence of shear strain on the damage evolution of micro-cavities, the damage evolution mechanism of GTN damage model is modified, and a damage model suitable for triaxiality of different stresses is established. Combined with the implicit stress update algorithm and explicit finite element calculation, the numerical calculation of the modified GTN model in the finite element software ABAQUS was implemented by using the VUMAT subroutine. By simulating the damage evolution and fracture behavior of pure shear and shear-tensile specimens, the validity of the modified GTN model under different stress triaxial loading conditions is verified. The modified GTN damage model was used to simulate the initiation and propagation of cracks in the strip with edge notches during the rolling process. The simulation results agree well with the experimental results, which show that the model can effectively be used for the extended behavior of strip defects during rolling Analysis and prediction. The simulation and experimental results show that during the rolling process, both the front and the back of the notch will initiate cracks and the crack propagation at the back edge will be more obvious.