Abstract In the present work, the normalization (NM) method was used to obtain J integral resistance (J-R) curves based on clamped single edge notched tension (SENT) specimens. The SENT fracture toughness tests using API X80 pipeline steel were carried out for a series of crack depth to specimen width ratios (a/W) and thickness to specimen width ratios (B/W), corresponding to varying in-plane and out-of-plane constraint conditions. To validate the normalization method, the unloading compliance (UC) method was adopted to derive the J-R curves for those clamped SENT specimens. In particular, two NM methods (modified NM method and unmodified NM method) are discussed and compared, and the experimental results indicated that the J-R curves calculated by the modified NM method have a better accuracy. Then, to quantify the modified NM method, the J-R curves, power law curve fitting parameters and the tearing modulus obtained from two methods (UC method and modified NM method) are compared. The comparison shows that good agreements are achieved among those methods. Moreover, three-dimensional finite element method (FEM) with GTN constitutive model is also used to determine J-R curves based on clamped SENT specimens. It is demonstrated that the modified NM method is an effective alternative tool for determining J-R curves of X80 steel based on clamped SENT specimens with different a/W and B/W ratios.

中文翻译：

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使用具有不同平面内和平面外约束的夹紧 SENT 试样确定 JR 曲线的修正归一化方法的应用

摘要 在目前的工作中，基于夹紧的单边缺口张力（SENT）试样，使用归一化（NM）方法获得J积分电阻（JR）曲线。使用 API X80 管线钢对一系列裂纹深度与试样宽度比 (a/W) 和厚度与试样宽度比 (B/W) 进行了 SENT 断裂韧性测试，对应于不同的面内和面外-平面约束条件。为了验证归一化方法，采用卸载柔量 (UC) 方法来推导出那些夹紧的 SENT 试样的 JR 曲线。特别是对两种NM方法（改进NM方法和未改进NM方法）进行了讨论和比较，实验结果表明，改进NM方法计算的JR曲线具有更好的精度。然后，为了量化修改后的 NM 方法，比较了两种方法（UC 法和修正 NM 法）得到的 JR 曲线、幂律曲线拟合参数和撕裂模量。比较表明，这些方法之间取得了良好的一致性。此外，还使用具有 GTN 本构模型的三维有限元方法 (FEM) 来确定基于夹紧的 SENT 试样的 JR 曲线。结果表明，基于不同 a/W 和 B/W 比的夹紧 SENT 试样，改进的 NM 方法是确定 X80 钢 JR 曲线的有效替代工具。具有 GTN 本构模型的三维有限元方法 (FEM) 也用于确定基于夹紧的 SENT 试样的 JR 曲线。结果表明，基于不同 a/W 和 B/W 比的夹紧 SENT 试样，改进的 NM 方法是确定 X80 钢 JR 曲线的有效替代工具。具有 GTN 本构模型的三维有限元方法 (FEM) 也用于确定基于夹紧的 SENT 试样的 JR 曲线。结果表明，基于不同 a/W 和 B/W 比的夹紧 SENT 试样，改进的 NM 方法是确定 X80 钢 JR 曲线的有效替代工具。