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Damage detection in rotating objects using position-triggered thermography
Engineering Failure Analysis ( IF 4.4 ) Pub Date : 2020-05-29 , DOI: 10.1016/j.engfailanal.2020.104642
Pedro J. Sousa , Francisco Barros , Nuno V. Ramos , Paulo J. Tavares , Pedro M.G.P. Moreira

Damage detection using non-destructive testing techniques is important to prevent damage in structures with long operating times. In the case of rotating structures with minimal downtime, such as wind turbines, it is advantageous to be able to detect these damages during operation. Thermography is a method that is capable of performing these measurements, but can still have some difficulties in field application. One such difficulty resides in the necessity of properly aligning each image with the previous ones to obtain difference thermograms with good quality. Thus, the present work proposes a method to properly align images by synchronizing the termographic camera with the rotation of the object, using only external non-contact devices, all positioned on the same side of the specimen. In this case, a photodetector is used in a high-amplification mode, working like a single-pixel camera. It outputs a grey level signal that will vary when a blade passes in front of it. By detecting this change, it is possible to trigger the camera and/or a heat source in the correct angular position, and use the acquired images to obtain good quality thermograms. This approach was applied to defect detection in rotating carbon fibre blades from a 450-size RC helicopter. It was possible to obtain results in these dynamic experiments that were in agreement with the ones obtained in a static approach.



中文翻译:

使用位置触发热像仪检测旋转物体中的损伤

使用非破坏性测试技术进行损坏检测对于防止长时间运行的结构损坏至关重要。在停机时间最短的旋转结构(例如风力涡轮机)的情况下,能够在运行期间检测到这些损坏是有利的。热成像是一种能够执行这些测量的方法,但是在现场应用中仍然会遇到一些困难。这样的困难之一在于必须使每个图像与先前的图像正确对准以获得高质量的差示热分析图。因此,本发明提出了一种方法,通过仅使用全部位于样本的同一侧上的外部非接触装置,通过使术语相机与物体的旋转同步来适当地对准图像。在这种情况下,光电探测器以高放大倍率模式使用,就像单像素相机一样工作。它输出一个灰度信号,当刀片从其前面通过时,该信号将发生变化。通过检测此变化,可以在正确的角度位置触发相机和/或热源,并使用获取的图像获得高质量的温度记录图。该方法已应用于从450尺寸的RC直升机旋转的碳纤维叶片中的缺陷检测。在这些动态实验中可以获得与静态方法获得的结果一致的结果。并使用获取的图像来获得高质量的温度记录图。该方法已应用于从450尺寸的RC直升机旋转的碳纤维叶片中的缺陷检测。在这些动态实验中可以获得与静态方法获得的结果一致的结果。并使用获取的图像来获得高质量的温度记录图。该方法已应用于从450尺寸的RC直升机旋转的碳纤维叶片中的缺陷检测。在这些动态实验中可以获得与静态方法获得的结果一致的结果。

更新日期:2020-05-29
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