The aim of the present work is to contribute to the characterization of the biaxial tensile behavior of commercially pure titanium, under various in-plane loading conditions at room temperature, by a non-contact digital image correlation system. Several loading conditions, with load ratio ranging from 4:0 to 0:4 and displacement rate ranging from 0.001 to 0.1 mm/s, are examined. It is found that the yield strength and ultimate tensile strength of biaxial sample are greater than that of uniaxial sample, where the equi-biaxial sample shows the highest strength. It is also observed that increase in strain rate leads to remarkable improvement of tensile strength. Fractographic analysis indicates that the shape and size of dimples are load ratio and strain rate dependent. Additionally, a modified Johnson–Cook constitutive model was proposed to account for the effect of strain rate on biaxial tensile deformation. The experimental results are in good agreement with the simulated results, indicating that the proposed model is reliable to predict biaxial tensile deformation of commercially pure titanium at different strain rates.

中文翻译：

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不同平面载荷比和应变速率下市售纯钛的双轴拉伸行为

本工作的目的是通过一种非接触式数字图像相关系统，在室温下在各种面内加载条件下，对商用纯钛的双轴拉伸性能进行表征。检查了几种载荷条件，载荷比从4：0到0：4，位移速率从0.001到0.1 mm / s。发现双轴样品的屈服强度和极限抗拉强度要大于单轴样品，其中等双轴样品表现出最高的强度。还观察到，应变率的增加导致抗张强度的显着改善。分形分析表明，凹痕的形状和大小取决于载荷比和应变率。另外，提出了一种改良的Johnson-Cook本构模型，以说明应变率对双轴拉伸变形的影响。实验结果与模拟结果吻合良好，表明所提出的模型能够可靠地预测不同应变速率下商业纯钛的双轴拉伸变形。