The fatigue properties of soft materials, including fatigue crack initiation and propagation, fatigue life and threshold, have been a significant concern in the past few decades. Measuring the fatigue crack growth rate (FCGR) curve is a standard method to characterize fatigue fracture and has been extensively studied in the literature. Conventional methods employing a pure shear configuration measure only one data point on the FCGR curve per test run. Thus, obtaining the whole FCGR curve with numerous data points becomes excessively time-consuming. This work proposes a high-throughput experimental method for measuring the FCGR curve of soft materials. We prepare ten thermoplastic polyurethane (TPU) specimens in single edge notch tensile configuration with different precut crack lengths, use a mechanical mechanism to apply the same cyclic loads to the ten specimens simultaneously, and identify the crack growth of each specimen by image processing. The proposed high-throughput experimental method enables the measurement of over 90 data points on the FCGR curve in a single test run, facilitating the acquisition of the entire curve with just two runs. The obtained FCGR curve exhibits a linear relationship within its middle region on double logarithmic coordinates. The proposed method is further applied to study the effect of temperature on the FCGR curve of TPU specimens. The current experimental setup can be further optimized to accommodate a wider range of soft materials with diverse mechanical properties and specific loading conditions.

中文翻译：

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测量软材料疲劳裂纹扩展速率曲线的高通量实验方法

软材料的疲劳性能，包括疲劳裂纹萌生和扩展、疲劳寿命和阈值，在过去几十年中一直受到人们的广泛关注。测量疲劳裂纹扩展率 (FCGR) 曲线是表征疲劳断裂的标准方法，并已在文献中得到广泛研究。采用纯剪切配置的传统方法每次测试仅测量 FCGR 曲线上的一个数据点。因此，获得具有大量数据点的整个 FCGR 曲线变得非常耗时。这项工作提出了一种测量软材料 FCGR 曲线的高通量实验方法。我们制备了十个具有不同预切裂纹长度的单边缺口拉伸配置的热塑性聚氨酯（TPU）样本，使用机械机构同时对十个样本施加相同的循环载荷，并通过图像处理识别每个样本的裂纹扩展。所提出的高通量实验方法可以在一次测试运行中测量 FCGR 曲线上的 90 多个数据点，从而只需两次运行即可获取整个曲线。得到的FCGR曲线在双对数坐标的中间区域呈现线性关系。该方法进一步应用于研究温度对 TPU 样品 FCGR 曲线的影响。当前的实验设置可以进一步优化，以适应更广泛的具有不同机械性能和特定负载条件的软材料。