This study investigated the stress–strain behavior of seamless pipes in the hoop direction using the ring expansion test, which is a non-standardized mechanical testing technique used for evaluating the mechanical properties of round tubes. However, this technique has limitations, such as unidentified specimen geometry, strain measurement, and the estimation of friction coefficients. The study employed experimental, numerical, and analytical methodologies to address these limitations and throughout the study, a novel hoop stress correlation factor (K) was identified to be multiplied by the hoop stress derived equation for reduced section ring specimens. The experimental strain was measured using a newly derived analytical equation, and a mathematical predictive model was developed to estimate the K-factor using the Design of Experiment (DoE) and Design-Expert statistical software. The study concluded that the ring expansion test is a promising technique for evaluating the mechanical properties of seamless pipes similar to the unified axial tensile stress–strain behavior. However, future research is needed to estimate the hoop stress correlation value (K) for all ring geometries. The study's finding of the novel hoop stress correlation factor (K) in the case of a reduced section ring specimen is particularly noteworthy, as it addresses a significant research gap in the field.

本研究使用环膨胀试验研究了无缝管在环向方向上的应力应变行为，这是一种用于评估圆管机械性能的非标准化机械试验技术。然而，该技术具有局限性，例如未知的样本几何形状、应变测量和摩擦系数的估计。该研究采用实验、数值和分析方法来解决这些局限性，并且在整个研究过程中，确定了一种新的环向应力相关因子 (K)，该因子可乘以截面减小的环样本的环向应力导出方程。使用新导出的分析方程测量实验应变，并使用实验设计 (DoE) 和 Design-Expert 统计软件开发数学预测模型来估计 K 因子。研究得出的结论是，环膨胀试验是一种很有前景的技术，用于评估无缝管的机械性能，类似于统一的轴向拉伸应力-应变行为。然而，未来的研究需要估计所有环几何形状的环向应力相关值 (K)。该研究在截面减小的环样本的情况下发现了新的环向应力相关因子 (K)，这一发现特别值得注意，因为它解决了该领域的一个重大研究空白。