Tensile testing is widely used for the mechanical characterization of materials subjected to superplastic deformation. At the same time, it is known that the obtained flow data are affected by specimen geometry. Thus, they characterize the specimen rather than the material. This work provides the numerical analysis aimed to study how the material flow behavior affects the results of tensile tests. The simulations were performed by the finite element method in Abaqus software, utilizing user-defined procedures for calculation of forces acting on the crossheads. The accuracy of tensile testing is evaluated by the difference between the input material flow behavior specified in the simulations and the output one, obtained by the standard ASTM E2448 procedure based on the predicted forces. The results revealed that the accuracy of the superplastic tensile test is affected by the material properties. Even if the material flow behavior follows the Backofen power law, which is invariant for the effective strain, the output stress–strain curves demonstrate significant strain hardening and softening effects. The relation between the basic superplastic characteristics and the tensile test errors is described and analyzed.

中文翻译：

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材料性能对超塑性拉伸试验精度的影响

拉伸测试广泛用于对超塑性变形材料进行机械表征。同时，已知获得的流量数据受样品几何形状的影响。因此，它们表征样品而不是材料。这项工作提供了数值分析，旨在研究材料的流动行为如何影响拉伸试验的结果。模拟是通过Abaqus软件中的有限元方法进行的，利用用户定义的程序来计算作用在十字头上的力。通过在模拟中指定的输入材料流动行为与输出之间的差异来评估拉伸测试的准确性，该输出是通过标准ASTM E2448程序基于预测的力获得的。结果表明，超塑性拉伸试验的准确性受材料性能的影响。即使材料的流动行为遵循有效力不变的Backofen幂定律，输出应力-应变曲线也显示出明显的应变硬化和软化效果。描述并分析了基本超塑性特征与拉伸试验误差之间的关系。