The main purpose of this study is to exhibit failure prediction capability of polynomial-based yield functions with a basic damage model. For this purpose, a constitutive model considering anisotropic plasticity and ductile fracture was developed. In this model, anisotropic plastic behavior of dual phase steels, namely DP600 and DP800, was described by quadratic Hill48 and non-quadratic anisotropic homogeneous the fourth-order polynomial (HomPol4) stress potentials and the generalized plastic work criterion from ductile damage models was used for the prediction of fracture initiation. The model has been implemented into an implicit finite element (FE) code. The parameters of the constitutive model were calibrated with uniaxial tensile tests performed in different directions with respect to the rolling direction of the materials and anisotropic stress potentials were evaluated by comparison of the predicted in-plane variations of the plastic properties (yield stress ratios and Lankford coefficients), and yield locus contours with experimental data. The calibrated model was firstly applied to uniaxial tensile test and then to a hole expansion test to predict fracture. The stroke values at fracture, hole expansion ratios (HER) and fracture locations were investigated. Any significant difference between the anisotropic stress potentials was not observed in terms of HER predictions, however plastic work criterion in conjunction with HomPol4 function predicted the crack initiation locations accurately on the fractured samples. Afterward, the Lode parameter and stress triaxiality effects were investigated in fracture stroke prediction. Since the HomPol4 predictions of fracture initiation locations are accurate, the predicted HomPol4 results from the generalized plastic work criterion were compared with the modified Mohr-Coulomb ductile fracture model results. A significant improvement was observed in the fracture displacement predictions. However, it is seen that the failure location predictions of both models were the same. From these results, it can be concluded that the HomPol4 yield criterion has an effective potential to predict the failure locations even though with a basic damage model. In the current study, the out-of-plane anisotropy effect was assessed as well. To this end, Hill48’s parameter correlated with the out-of-plane shear components were adjusted. It was found that the out-of-plane anisotropy has a negligible effect on the predictions of HER and fracture initiation location.

本研究的主要目的是通过基本损伤模型展示基于多项式的屈服函数的失效预测能力。为此，开发了考虑各向异性塑性和延性断裂的本构模型。在该模型中，双相钢（即 DP600 和 DP800）的各向异性塑性行为通过二次 Hill48 和非二次各向异性均匀四阶多项式 (HomPol4) 应力势来描述，并使用延性损伤模型的广义塑性功准则用于预测断裂起始。该模型已被实施为隐式有限元 (FE) 代码。本构模型的参数通过相对于材料轧制方向的不同方向进行的单轴拉伸试验进行校准，并通过比较预测的塑性性能的面内变化（屈服应力比和兰克福德应力比）来评估各向异性应力势。系数），并根据实验数据得出轨迹轮廓。校准后的模型首先应用于单轴拉伸试验，然后应用于扩孔试验以预测断裂。研究了断裂时的冲程值、扩孔率 (HER) 和断裂位置。就 HER 预测而言，未观察到各向异性应力势之间存在任何显着差异，然而，塑性功准则与 HomPol4 函数结合可以准确预测断裂样品上的裂纹萌生位置。随后，研究了 Lode 参数和应力三轴性在断裂行程预测中的影响。由于 HomPol4 对断裂起始位置的预测是准确的，因此将广义塑性功准则预测的 HomPol4 结果与修正的 Mohr-Coulomb 延性断裂模型结果进行了比较。在裂缝位移预测中观察到显着的改进。然而，可以看出两个模型的故障位置预测是相同的。从这些结果可以得出结论，即使使用基本损伤模型，HomPol4 屈服准则也具有预测失效位置的有效潜力。在当前的研究中，还评估了面外各向异性效应。为此，调整了 Hill48 与面外剪切分量相关的参数。研究发现，面外各向异性对 HER 和断裂起始位置的预测影响可以忽略不计。