The occurrence of crack closure significantly impacts the fatigue life of materials and structural components. Whether it is induced by the nature of the loading, the fabrication process or the geometry of the structure, its magnitude and effect should be considered to further improve predictive models of fatigue crack propagation. However, the definition of reliable experimental methods for the observation and assessment of fatigue crack closure, and in particular suited to structure testing, remains a challenge. The present study aims to provide a novel approach for the assessment of fatigue crack closure via the continuous wavelet transform of infrared thermography data. The processing of the temperature signal close to the crack in a coherent time–frequency space allows for the identification of crack closing and opening instants associated with high-frequency components. The method is meant to be suited to any testing configuration (conventional compact tension specimen or full-scale structures) with minimum operator-dependent parameters.

中文翻译：

---

通过红外热成像信号的小波变换评估疲劳裂纹闭合


裂纹闭合的发生会显著影响材料和结构部件的疲劳寿命。无论是由载荷的性质、制造过程还是结构的几何形状引起的，都应考虑其大小和影响，以进一步改进疲劳裂纹扩展的预测模型。然而，定义用于观察和评估疲劳裂纹闭合的可靠实验方法，特别是适用于结构测试的实验方法仍然是一个挑战。本研究旨在通过红外热成像数据的连续小波变换为评估疲劳裂纹闭合提供一种新的方法。在相干时频空间中处理靠近裂纹的温度信号，可以识别与高频元件相关的裂纹闭合和打开时刻。该方法适用于任何测试配置（传统的紧凑拉伸试样或全尺寸结构），具有最小的操作员相关参数。