Validation of Acoustic Emission (AE) Crack Detection in Aerospace Grade Steel Using Digital Image Correlation
Validation of Acoustic Emission (AE) Crack Detection in Aerospace Grade Steel Using Digital Image Correlation
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DOI：
10.4028/www.scientific.net/amm.24-25.221
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发表时间：
2010-06
期刊：
影响因子：
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通讯作者：
R. Pullin;M. Eaton;J. Hensman;K. Holford;K. Worden;S. L. Evans
中科院分区：
文献类型：
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作者：
R. Pullin;M. Eaton;J. Hensman;K. Holford;K. Worden;S. L. Evans
声发射（AE）是一种被动形式的无损检测，它依赖于对裂纹扩展过程中释放的应力波的检测和分析。声发射技术已成功地应用于许多工业领域，但在航空航天工程方面仍存在一些怀疑.报告的调查详细描述了一个承受疲劳载荷的四点弯曲试验样本。这项试验是一个更大的计划的一部分，该计划旨在证明使用AE检测起落架结构中裂纹萌生和增长的技术准备水平（TRL）为5。完成的测试要求必须监测裂纹扩展，以便与检测到的和定位的AE信号进行比较。裂纹监测的方法必须是非接触式的，以免在裂纹区域产生AE的摩擦源，从而防止使用裂纹口张开位移计。此外，必须避免样本表面上的粘合剂，以消除检测到的AE来自粘合剂开裂的可能性，因此不可能使用应变计或箔裂纹计。研究了一种利用数字图像相关技术监测裂纹扩展的方法。在1000次循环间隔的疲劳加载期间停止测试，并在峰值载荷下捕获DIC图像。在整个调查过程中观察到由于裂纹扩展的位移，并将结果与检测到的AE信号进行比较。结果表明，AE和裂纹扩展之间存在明显的相关性，并进一步证明了TRL5用于使用AE检测起落架断裂。
Acoustic Emission (AE) is a passive form of non-destructive testing that relies on the detection and analysis of stress waves released during crack propagation. AE techniques are successfully employed number of industries there remains some scepticism in aerospace engineering. The reported investigation details a single four point bend test specimen undergoing fatigue loading. This test is part of a much larger programme designed to demonstrate a technology readiness level (TRL) of five of the use of AE to detect crack initiation and growth in landing gear structures. The completed test required that crack growth had to be monitored to allow a comparison with the detected and located AE signals. The method of crack monitoring had to be non-contact so as not to produce frictional sources of AE in the crack region, preventing the use of crack mouth opening displacement gauges. Furthermore adhesives on the specimen surface had to be avoided to eliminate the possibility that the detected AE was from adhesive cracking, thus the use of strain gauges or foil crack gauges was not possible. A method using Digital Image Correlation (DIC) to monitor crack growth was investigated. The test was stopped during fatigue loading at 1000 cycle intervals and a DIC image captured at peak load. The displacement due to crack growth was observed throughout the investigation and the results compared with the detected AE signals. Results showed a clear correlation between AE and crack growth and added further evidence of TRL5 for detecting fractures in landing gears using AE.