(清华大学，汽车安全与节能国家重点实验室，北京 100084)
摘 要: 通过单向拉伸与压缩试验，研究AZ31B镁合金挤压材料的力学性能，并建立相应的本构模型。结果表明：室温下AZ31B镁合金挤压材料的宏观力学性能存在显著的各向异性和拉压非对称屈服的现象，且在塑性流动过程中，屈服面的演化也呈现出各向异性的特点，即畸变硬化特性。基于系统的试验结果，结合考虑了各向异性和拉压非对称性的CPB06屈服面函数，采用解析函数形式的本构参数来描述畸变硬化特性，建立了一种唯象的镁合金材料塑性流动本构模型。通过用户材料子程序VUMAT，将本构模型应用于缺口试件拉伸的有限元模拟中，计算结果与试验结果吻合较好，证实了本构模型的适用性。
关键字: 镁合金；畸变硬化；本构模型；有限元模拟
（Tsinghua University, State Key Laboratory of Automotive Safety and Energy, Beijing 100084, China）
Abstract:By conducting uniaxial tension and compression tests, the mechanical properties of extruded AZ31B magnesium alloy were studied and a suitable constitutive model was established. The results show that the yielding response of extruded AZ31B alloy exhibits significant anisotropy and tension-compression asymmetry, and the evolution of yield surface during plastic flow also exhibits great anisotropy, known as distortional hardening effect. By introducing an analytical evolving law for the distortional hardening effect, a phenomenological constitutive model was established based on the CPB06 yield function, which accounts for both anisotropy and tension-compression asymmetry. The model was programmed to the user material subroutine interface VUMAT and applied to the finite element simulation of the tension tests of a grooved specimen. The computational results coincide well with the experimental ones, which demonstrates the predictive efficiency of this constitutive model.
Key words: magnesium alloys; distortional hardening; constitutive model; finite element simulation
