The Wavelet-Based Self-similarity Analysis for the Detection of Fatigue Microcrack by the Joint Scanning Laser Thermography

The laser thermography is an emerging non-destructive testing technique which is a suitable method to detect surface cracks. In this study, we adopted the joint scanning laser thermography to detect the fatigue microcrack on the aluminum alloy surface. We analyzed the temperature distribution curve...

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Bibliographic Details
Published in:International journal of thermophysics 2022-02, Vol.43 (2), Article 19
Main Authors: Yang, Jie, Dong, Lihong, Wang, Haidou, Di, Yuelan, Li, Ronghao, Lin, En
Format: Article
Language:English
Subjects:
Aluminum base alloys
Amplitudes
Classical Mechanics
Condensed Matter Physics
Fatigue cracks
Flaw detection
Geophysics
Industrial Chemistry/Chemical Engineering
Lasers
Microcracks
Nondestructive testing
Physical Chemistry
Physics
Physics and Astronomy
Process parameters
Scanning
Self-similarity
Signal to noise ratio
Surface cracks
Temperature distribution
Thermal resistance
Thermodynamics
Thermography
Waveforms
Wavelet analysis
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Summary:The laser thermography is an emerging non-destructive testing technique which is a suitable method to detect surface cracks. In this study, we adopted the joint scanning laser thermography to detect the fatigue microcrack on the aluminum alloy surface. We analyzed the temperature distribution curve derived from the surface for the characteristics that correlated with the thermal resistance effect of the crack, namely a significant change in the amplitude and a specific waveform. The two distinctive characteristics of the temperature signal that corresponded to the crack were analyzed under different parameters of the scanning process to deduce the optimal sampling point for the crack detection. Subsequently, the temperature distribution curve was subjected to the wavelet decomposition to improve the signal-to-noise ratio of the curve and the peak-to-peak ratio of the temperature signal that corresponded to the crack. On the basis of the similarity between the Daubechies wavelet and the waveform of the temperature signal that corresponded to the crack, we proposed a crack detection method based on the self-similarity analysis. The method indicated the amplitude and the waveform of the temperature signal that corresponded to the crack. Thus, the method is suitable for an industrial automated crack detection application.
ISSN:0195-928X
1572-9567
DOI:10.1007/s10765-021-02925-7