基于修正GTN模型的双相钢断裂失效判据研究

Study on fracture failure criterion of dual phase steel based on modified GTN model

在屈服函数中引入剪切损伤参数对GTN模型进行修正,对较广应力三轴度的失效进行预测;设计不同切口的剪切试验,并将修正的GTN模型以及双相钢DP780的材料参数和损伤参数编入VUMAT子程序,用ABAQUS进行仿真,获得双相钢失效时的临界应力三轴度T与其对应的剪切损伤,拟合出极限剪切损伤值与应力三轴度的函数关系曲线;然后结合颈缩断裂时的临界孔洞体积分数与应力三轴度的关系,建立适用于较广应力三轴度的DP780断裂失效细观判据;设计了拉弯成形试验并带入ABAQUS中进行仿真,证明得出的细观断裂判据能预测双相钢在冲压成形过程中出现的不同断裂现象。

Shear damage parameters were introduced in the yield function to modify the GTN model,and to predict the failure of wider stress triaxiality. The shear tests with different incisions were designed,then the modified GTN model and the material and damage parameters of dual phase steel DP780 were programmed into the VUMAT subroutine,and the simulation was carried out by ABAQUS. The critical stress triaxiality T and the corresponding shear damage when the dual phase steel failed were obtained,and the function relationship curve between the ultimate shear damage value and the stress triaxiality was fitted. Then combining the relationship between the critical voids volume fraction and the stress triaxiality when the neck collapsed,the DP780 fracture failure mesoscopic criterion for the wider stress triaxiality was established. The stretch bending forming test was designed and simulated in ABAQUS to prove that the mesoscopic fracture criterion can predict the different fracture phenomena of dual phase steel during stamping forming.