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为研究HCP结构单晶在塑性变形中的变形孪晶和塑性各向异性,采用基于晶体塑性本构理论的有限单元法,建立包含滑移与孪生变形机制的晶体塑性本构关系,发展了以应力作为自变量的牛顿-拉普森迭代方法,通过已有文献的试验数据验证模型的有效性,并利用此模型模拟AZ31单晶体在4种(即沿〈2110〉,〈0110〉,〈0001〉和〈0111〉方向)拉伸与压缩变形路径下的塑性变形行为,并获得了相应加载路径下的应力-应变关系曲线。数值计算结果表明,在不同加载路径下该模型可用于预测滑移系或孪生系的活动情况,以及描述孪生变体的活动数量、主要孪生变体和孪生交叉类型。由于机械孪晶具有的极性性质及其在材料非弹性变形中的重要作用,单晶材料表现出显著的各向异性与非对称性。
In order to study the twinning and plastic anisotropy of HCP single crystal in plastic deformation, a finite element method based on the plastic plastic constitutive theory was used to establish the plastic plastic constitutive relation of the crystal, including the slip and twin deformation mechanisms. The Newton-Raphson iterative method with stress as an independent variable is used to verify the validity of the model through the experimental data of the existing literature. The model is used to simulate the effect of AZ31 single crystals on four kinds of (ie, <2110>, <0110>, <0001> And <0111> directions), and obtained the stress-strain curve under the corresponding loading path. The numerical results show that the model can be used to predict the activity of the slip system or twin system under different loading paths and to describe the number of twin twins, the main twins and the twin crossover types. Due to the polar nature of mechanical twins and their important role in the inelastic deformation of materials, single crystal materials exhibit significant anisotropy and asymmetry.