The plastic range of crack tip opening displacement (CTOD) has been used for the experimental characterisation of fatigue crack growth for 2024‐T3 and 7050‐T6 aluminium alloys using digital image correlation (DIC). Analysis of a complete loading cycle allowed resolving the CTOD into elastic and plastic components. Fatigue tests were conducted on compact tension specimens with a thickness of 1 mm and a width of 20 mm at stress ratios of 0.1, 0.3 and 0.5. The range of plastic CTOD could be related linearly to da /dN independent of stress ratio for both alloys. To facilitate accurate measurements of CTOD, a method was developed for correctly locating the crack tip and a sensitivity analysis was performed to explore the effect of measurement position behind the crack tip on the CTOD. The plastic range of CTOD was demonstrated to be a suitable alternate parameter to the stress intensity factor range for characterising fatigue crack propagation. A particularly innovative aspect of the work is that the paper describes a DIC‐based technique that the authors believe gives a reliable way to determine the appropriate position to measure CTOD.

中文翻译：

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使用DIC在2024-T3和7050-T6铝合金中将塑料CTOD作为疲劳裂纹扩展的表征参数

裂纹尖端开口位移的塑性范围（CTOD）已用于通过数字图像相关（DIC）对2024-T3和7050-T6铝合金进行疲劳裂纹扩展的实验表征。通过分析整个加载周期，可以将CTOD分解为弹性和塑料组件。在厚度为1 mm，宽度为20 mm的紧凑型拉伸试样上以0.1、0.3和0.5的应力比进行疲劳测试。塑料CTOD的范围可能与da / dN线性相关与两种合金的应力比无关。为了促进CTOD的准确测量，开发了一种方法来正确定位裂纹尖端，并进行了敏感性分析，以探索裂纹尖端后面的测量位置对CTOD的影响。CTOD的塑性范围被证明是用于表征疲劳裂纹扩展的应力强度因子范围的合适替代参数。这项工作的一个特别创新之处在于，本文描述了一种基于DIC的技术，作者认为该技术为确定测量CTOD的合适位置提供了可靠的方法。