韧性断裂准则参数标定及其在DP590中的应用

为研究DP590高强钢板材的韧性断裂力学性能,以DF2012韧性断裂准则为理论基础,设计6种包含不同应力状态的拉伸试样来获取材料的塑性流动和断裂参数,采用一种实验-模拟混合方法标定韧性断裂准则的参数.准确地描述材料发生断裂前的塑性行为是韧性断裂准则参数标定的关键,以新提出的各向异性Drucker屈服准则和一种修正的Voce硬化准则表征DP590的塑性行为,使用Fortran语言将该本构模型编译为VUMAT子程序嵌入ABAQUS仿真软件中进行试样的拉伸模拟.实验和模拟对比表明,所构建的本构模型可以准确地预测不同试样沿着轧制方向各个角度的力程曲线.在拉伸实验和标定的本构模型基础上,标定DF2012韧性断裂准则的参数并构建DP590在应力三轴度和断裂应变二维空间中的断裂轨迹.与3种经典的韧性断裂准则Cockcroft-Latham、Clift和Rice-Tracey进行比较,使用Fortran语言将DF2012韧性断裂准则和本构模型一起嵌入ABAQUS仿真软件对不同试样的断裂进行模拟,结果表明:基于实验-模拟混合法标定的DF2012韧性断裂准则能够合理地构建DP590的断裂轨迹曲线和准确地预测不同应力状态下拉伸试样断裂的发生.

Parameter calibration of ductile fracture criterion and its application on DP590

To study the ductile fracture mechanical properties of DP590 high-strength steel sheet, based on the DF2012 ductile fracture criterion, six types of tensile specimens under different stress states were designed to obtain the plastic flow and fracture parameters of the materials. In this study, an experiment-simulation hybrid method was used to calibrate the parameters of the ductile fracture criterion, for which accurately describing the plastic behavior before fracture is the key to calibrate the parameters of ductile fracture criterion. A newly proposed anisotropic Drucker yield criterion and a modified Voce hardening criterion were used to characterize the plastic behavior of DP590, and the constitutive model was compiled into a VUMAT subroutine by Fortran language and embedded into ABAQUS simulation software for tensile simulation of specimens. The experimental and simulation results show that the constitutive model can accurately predict the force curves of different specimens at different angles along the rolling direction. Based on the tensile experiments and the calibrated constitutive model, the parameters of DF2012 ductile fracture criterion were calibrated and the fracture locus of DP590 in two-dimensional space of stress triaxiality and fracture strain was constructed. And three typical ductile fracture criteria (Cockcroft-Latham, Clift and Rice-Tracey) were used for comparison. The results show that DF2012 ductile fracture criterion calibrated based on experiment-simulation hybrid method can reasonably construct the fracture locus of DP590 and accurately predict the fracture occurrence of tensile specimens under different stress states.