中文摘要：

通过光滑试件及不同曲率半径缺口圆柱试件的拉伸试验,实现对镁合金MB2的单向及多向应力状态加载。结合数值模拟分析,研究了不同试件在拉伸加载过程中应力状态的变化。以应力三轴度为参数,给出了镁合金MB2等效破坏应变的变化规律,在应力三轴度-等效破坏应变空间建立了镁合金MB2的失效破坏准则。利用扫描电镜对试件断口形貌进行观察,分析了导致材料宏观延性变化的微观损伤机理,对不同应力状态下镁合金MB2的失效破坏行为做出了合理解释。

英文摘要：

Based on tensile experiments for smooth specimens and notched cylinder specimens with different radius of curvature,magnesium alloy MB2 was loaded by uniaxial and multiaxial stress states.Combining numerical analysis,stress state variation in the tensile process of different specimens was investigated.Taking stress triaxiality as a parameter,the variation pattern of equivalent failure strain of magnesium alloy MB2 was given,and failure destruction criterion of magnesium alloy MB2 was established in the space of stress triaxiality and equivalent failure strain.The fracture morphology was observed by scanning electron microscope,and the micro damage mechanism which causes macroscopic ductility change of material was analyzed. The failure destruction behavior of magnesium alloy MB2 in different stress states was explained reasonably.