金属板材因其制造工艺而具有各向异性和应变硬化特性，二者对金属板材塑性加工的影响均不容忽视。Hill48各向异性塑性理论较好地描述了金属板材的正交各向异性，但以引入参考应力以及各向异性参数等比例变化的假设条件来描述金属板材后继屈服的加工硬化特性，与客观实际出入较大。多年来该模型及其在数值模拟应用中的问题仍未得到有效解决。鉴于此，本项目拟基于Hill48各向异性屈服准则，以塑性等效应变为基本参考变量，用尽可能少的单向拉伸实验数据，建立后继屈服各向异性参数与多个方向单向拉伸硬化曲线的耦合关联方程及其求解递推迭代算法，以各向异性参数随等效应变的变化来揭示后继屈服过程中各向异性和加工硬化的演变规律，从而建立完整精确的正交各向异性金属板材后继屈服材料模型，并将其嵌入大型数值模拟软件，实现同时考虑正交各向异性和后继屈服加工硬化的全程高精度模拟。具有完备应用基础理论，提高板材成形数值模拟精度的双重意义。

Anisotropy and strain hardening are two important properties of sheet metal, which are caused by the manufacturing process. The influence of both on the plastic processing of sheet metal can not be ignored. Hill48 anisotropic plasticity theory can describe the orthotropy of sheet metal well, but the work hardening characteristics of subsequent yield of sheet metal are described by introducing the reference yield stress and the hypothesis that anisotropic parameters vary in equal proportion, which is quite different from objective reality. For many years, the model and its problem of application in numerical simulation have not been effectively solved. Therefore, based on Hill48 orthotropic yield criterion, taking plastic equivalent strain as the basic reference variable, and using as few uniaxial tensile test data as possible, this project intends to establish the coupling correlation equation between the subsequent yield anisotropic parameters and uniaxial tensile hardening curves in multiple directions. Also the recursive iteration algorithm of the coupling correlation equation will be given. The evolution law of anisotropy and work hardening during subsequent yield process is revealed by the variation of anisotropic parameters with equivalent strain, then a complete and accurate subsequent yield material model of orthotropic metal sheet is established. It will be embedded in the numerical simulation software to achieve high-precision simulation of the whole process considering both orthotropy and subsequent yield hardening. The achievements of this project have great significance in completing the application of basic theory and improving the accuracy of numerical simulation of sheet metal forming.