(清華大學(xué)，汽車安全與節(jié)能國(guó)家重點(diǎn)實(shí)驗(yàn)室，北京 100084)
摘 要: 通過(guò)單向拉伸與壓縮試驗(yàn)，研究AZ31B鎂合金擠壓材料的力學(xué)性能，并建立相應(yīng)的本構(gòu)模型。結(jié)果表明：室溫下AZ31B鎂合金擠壓材料的宏觀力學(xué)性能存在顯著的各向異性和拉壓非對(duì)稱屈服的現(xiàn)象，且在塑性流動(dòng)過(guò)程中，屈服面的演化也呈現(xiàn)出各向異性的特點(diǎn)，即畸變硬化特性。基于系統(tǒng)的試驗(yàn)結(jié)果，結(jié)合考慮了各向異性和拉壓非對(duì)稱性的CPB06屈服面函數(shù)，采用解析函數(shù)形式的本構(gòu)參數(shù)來(lái)描述畸變硬化特性，建立了一種唯象的鎂合金材料塑性流動(dòng)本構(gòu)模型。通過(guò)用戶材料子程序VUMAT，將本構(gòu)模型應(yīng)用于缺口試件拉伸的有限元模擬中，計(jì)算結(jié)果與試驗(yàn)結(jié)果吻合較好，證實(shí)了本構(gòu)模型的適用性。
關(guān)鍵字: 鎂合金；畸變硬化；本構(gòu)模型；有限元模擬
（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
