Wang Kun, Zhao Xilong, Cao Zeyu
School of Civil Engineering, Lanzhou Jiaotong University, 88 Anning West Road, Anning District, Lanzhou 730070, China.
School of Materials Science and Engineering, Lanzhou Jiaotong University, 88 Anning West Road, Anning District, Lanzhou 730070, China.
Materials (Basel). 2024 Aug 25;17(17):4203. doi: 10.3390/ma17174203.
The mechanical properties of local materials subjected to various stress triaxialities were investigated via self-designed small punch tests and corresponding simulations, which were tailored to the geometry and notch forms of the samples. The finite element model was developed on the basis of the actual test method. After verifying the accuracy of the simulation, the stress, strain, and void volume fraction distributions of the Ti6Al4V titanium alloy under different stress states were compared and analyzed. The results indicate that the mechanical properties of the local material significantly differ during downward pressing depending on the geometric shape. A three-dimensional tensile stress state was observed in the center area, where the void volume fraction was greater than the fracture void volume fraction. The fracture morphology of the samples further confirmed the presence of different stress states. Specifically, the fracture morphology of the globular head samples (with or without U-shaped notches) predominantly featured dimples. Modifying the specimen's geometry effectively increased stress triaxiality, facilitating the determination of the material's constitutive relationship under varying stress states.
通过自行设计的小冲孔试验及相应模拟，研究了承受不同应力三轴性的局部材料的力学性能，这些试验和模拟是根据样品的几何形状和缺口形式定制的。有限元模型是在实际试验方法的基础上建立的。在验证模拟的准确性之后，对Ti6Al4V钛合金在不同应力状态下的应力、应变和孔隙体积分数分布进行了比较和分析。结果表明，局部材料在向下压制过程中的力学性能因几何形状的不同而有显著差异。在中心区域观察到三维拉伸应力状态，该区域的孔隙体积分数大于断裂孔隙体积分数。样品的断口形貌进一步证实了不同应力状态的存在。具体而言，球形头部样品（有或没有U形缺口）的断口形貌主要为韧窝。改变试样的几何形状有效地增加了应力三轴性，有助于确定材料在不同应力状态下的本构关系。
