Abstract One of the main challenges of the mode I double cantilever beam (DCB) test is the simultaneous determination of the applied load and displacement with the developing delamination length. The present work addresses this issue by side-view tracking the crack propagation by means of digital image correlation (DIC). Two different reduction methods were developed to determine the crack length from the DIC data. On the one hand, the crack tip position was defined by the high strain concentration in the immediate vicinity of the crack tip, and on the other hand, by crack tip opening displacement (CTOD). The data obtained enabled the calculation of the energy release rate of carbon fibre reinforced thermoplastic specimens with either run-arrest or stable crack extension. For reasons of comparability, top surface analysis (TSA), as recently reported, was also carried out. Following this approach, the crack propagation was tracked applying DIC to the top specimen surface. The methods developed showed a good correlation with both the standardised procedure and TSA. It was shown that DIC can be used as an alternative to the conventional optical measuring tools to follow the crack propagation in the mode I DCB test.

中文翻译：

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通过数字图像关联自动监测热塑性复合材料模式 I 测试中的裂纹扩展

摘要 I 型双悬臂梁 (DCB) 测试的主要挑战之一是同时确定施加的载荷和位移以及分层长度的发展。目前的工作通过数字图像相关 (DIC) 的侧视跟踪裂纹扩展来解决这个问题。开发了两种不同的缩减方法来根据 DIC 数据确定裂纹长度。一方面，裂纹尖端位置由裂纹尖端附近的高应变集中定义，另一方面，由裂纹尖端张开位移（CTOD）定义。获得的数据能够计算碳纤维增强热塑性试样的能量释放率，无论是停止运行还是稳定裂纹扩展。出于可比性的原因，顶面分析 (TSA)，正如最近报道的那样，也进行了。按照这种方法，将 DIC 应用到顶部试样表面来跟踪裂纹扩展。开发的方法显示出与标准化程序和 TSA 的良好相关性。结果表明，DIC 可用作传统光学测量工具的替代品，以跟踪模式 I DCB 测试中的裂纹扩展。