Determination of stress-strain relationship and anisotropy for accurate CAE of sheet metal forming

为了精确地数值模拟板料成形过程，采用合适的材料模型来描述板料的加工硬化、Bauschinger效应和各向异性是至关重要的。针对大应变加工硬化特性，通过面内循环弯曲试验确定了Swift-Voce组合模型中的权系数。为了确定Bauschinger效应，从三点循环弯曲实验中识别了Yoshida-Uemori随动硬化模型的一组材料参数。 对于各向异性，提出了六次多项式型屈服函数，并基于该模型描述了各向异性随塑性应变的演化。

For accurate numerical simulation of sheet metal forming, the use of appropriate material models that describe the workhardening, the Bauschinger effect and the anisotropy of sheet metals is of vital importance.In the present work, material properties at a large strain were determined by the elasto-plasticity inverse approach. For the large strain workhardening characteristic, the weighting parameter in the combined Swift-Voce model was identified from an in-plane cyclic bending experiment. For the determination of the Bauschinger effect, a set of material parameters of the Yoshida-Uemori kinematic hardening model were identified from a three-point cyclic bending experiment. For the anisotropy, the sixth-order polynomial type yield function was proposed, and based on the model, the description of the evolution of anisotropy with increasing plastic strain was presented.