基于J-C模型的镁合金MB2动静态拉伸破坏行为

发布时间：2018-01-13 07:32

本文关键词：基于J-C模型的镁合金MB2动静态拉伸破坏行为　出处：《爆炸与冲击》2017年06期 　论文类型：期刊论文

【摘要】：为了研究不同应力状态和应变率条件下镁合金MB2的拉伸破坏行为,利用材料试验机和分离式Hopkinson拉杆(SHTB),对镁合金MB2的光滑及缺口圆柱试件进行了动静态拉伸加载;拟合得到了镁合金MB2的动静态拉伸本构关系,建立了其修正的Johnson-Cook失效破坏准则,并对不同试件的拉伸破坏行为进行了数值模拟;利用SEM对宏观破坏模式对应的微观损伤机理进行了分析。结果表明,随着应力三轴度的增加,镁合金MB2的等效破坏应变先增大后减小,宏观破坏模式由剪切转为正拉断,微观损伤机制由混合断裂转变为韧窝断裂;而随着应变率的增加,等效破坏应变不断减小,破坏模式不发生改变。Johnson-Cook本构关系和修正后的Johnson-Cook失效破坏准则能较好地拟合动态静态拉伸实验结果并预测不同试件的杯锥形破坏特征。
[Abstract]:In order to study the tensile failure behavior of magnesium alloy MB2 under different stress state and strain rate, the material testing machine and split Hopkinson rod were used. The smooth and notched cylindrical specimens of magnesium alloy MB2 were subjected to static and dynamic tensile loading. The static and static tensile constitutive relation of magnesium alloy MB2 was obtained, the modified Johnson-Cook failure criterion was established, and the tensile failure behavior of different specimens was simulated numerically. The microscopic damage mechanism corresponding to the macroscopic failure mode was analyzed by SEM. The results show that the equivalent failure strain of magnesium alloy MB2 increases first and then decreases with the increase of stress triaxiality. The macroscopic failure mode changed from shear to normal tensile fracture, and the microscopic damage mechanism changed from mixed fracture to dimple fracture. The equivalent failure strain decreases with the increase of strain rate. The failure mode does not change. Johnson-Cook constitutive relation and the modified Johnson-Cook failure failure criterion can fit the dynamic static tensile test results and predict different results. The characteristics of cup cone failure of the specimen.
【作者单位】：中国工程物理研究院总体工程研究所;
【基金】：国家自然科学基金项目(11472257) 中国工程物理研究院总体工程研究所创新与发展基金项目(13CXJ09)
【分类号】：O346
【正文快照】： 镁合金是一种潜力巨大的轻质工程材料,有着广阔的应用前景,其中MB2是镁合金的典型代表。材料在复杂应力状态下的失效破坏行为是工程材料和结构设计的理论基础。目前,镁合金在动静态加载下的力学行为研究以单向应力状态为主[1-3],且能实现复杂应力动态加载的实验设备与技术尚不

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