中文摘要：

同时考虑滑移与孪生变形机制,在晶体塑性理论基础上建立镁合金晶体本构关系,分别提出滑移与孪生变形的硬化函数,并考虑滑移与孪生变形间的交互作用;结合Voronoi多晶集合体代表性体积单元（RVE）,对AZ31镁合金材料在单轴加载情形下进行数值模拟实验及细观分析。比较模拟结果与实验数据表明：采用晶体塑性本构关系及硬化函数能够合理预测镁合金宏观屈服行为、硬化演化与多晶织构演化,并可合理估计多晶体内的晶粒取向不均匀转动及晶粒内产生孪晶的体积分数分布。结果表明：镁合金宏观塑性行为取决于各滑移系与孪生系竞争启动的结果;拉伸孪生变形是引起多晶体形成强基面织构的主要原因;孪生变形导致晶粒取向转动与孪晶体积分数在多晶体内的分布极不均匀。

英文摘要：

The constitutive relation of Mg alloy was established with the crystal plasticity theory based on the mechanisms of slip and twinning deformations. The hardening functions of slip and twinning deformations were proposed in consideration of the interaction between the slip and twinning deformation. The numerical simulation and meso analysis for AZ31 Mg alloy under the uniaxial loading were carried out using the above constitutive relation and the hardening functions associated with a representative volume element （RVE） consisting of Voronoi polycrystalline aggregation. By comparing the simulation results and the experimental data, the present method is verified feasible to predict reasonably the macroscopic yield behavior, the hardening evolution and the polycrystalline texture evolution. The reasonable estimations for inhomogeneous rotation of grain orientation and the twin volume fraction in the polycrystalline can be attained. The results show that, the macroscopic plastic behavior of Mg alloy depends on the competitive result of activation slip and twinning systems; the tension twin deformation is the primary reason to the formation of typical （0001） basal texture in the polycrystalline; and the twin deformation leads to extremely inhomogeneous distribution for the orientation deflection and the twin volume fraction in the polycrystalline.