Laser Ultrasonic Imaging for Damage Visualization and Damage Accumulation Evaluation

This article describes a new damage visualization method to investigate and analyze propagating guided Lamb waves using analyses of wavefield spatial gradients. A laser ultrasonic interrogation system was used to create full-field ultrasonic data measurements for ultrasonic wavefield imaging. The laser scanning process was performed based on both a raster scan and a circle scan. From the high-resolution wavefield data, a spatial gradient–based image processing technique was developed using gradient vectors to extract features sensitive to defects. Local impedance changes at the damaged area would result in a local distortion of the waveform which was captured and quantified by the variation of the gradient vectors in the scanning area as time evolves. Such variation was accumulated over time with a statistical threshold filter to generate a gradient-orientation map for damage visualization. The proposed algorithm was capable of producing distinctive damage patterns when tested experimentally on a 3-mm aluminum plate with multiple simultaneous simulated defects. Compared to conventional techniques like local wavenumber estimation, the generation of the accumulated orientation map involves no filtering process in the frequency or wavenumber domain, at the expense of more accurate shaping of the defect. A spatial covariance analysis was adopted to locate damage from the results as well as to evaluate the correlation between different kinds of defects. Combining the proposed approach with conventional laser ultrasonic imaging techniques enables a fast and robust damage identification and characterization process which requires lower computational burden and practical operation.

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Long distance laser ultrasonic propagation imaging system for damage visualization

Optics and Lasers in Engineering ◽

10.1016/j.optlaseng.2011.07.011 ◽

2011 ◽

Vol 49 (12) ◽

pp. 1361-1371 ◽

Cited By ~ 31

Author(s):

Jung-Ryul Lee ◽

He-Jin Shin ◽

Chen Ciang Chia ◽

Dipesh Dhital ◽

Dong-Jin Yoon ◽

...

Keyword(s):

Imaging System ◽

Long Distance ◽

Laser Ultrasonic ◽

Ultrasonic Propagation ◽

Damage Visualization

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The Progress in Photoacoustic and Laser Ultrasonic Tomographic Imaging for Biomedicine and Industry: A Review

Applied Sciences ◽

10.3390/app8101931 ◽

2018 ◽

Vol 8 (10) ◽

pp. 1931 ◽

Cited By ~ 11

Author(s):

Anton Bychkov ◽

Varvara Simonova ◽

Vasily Zarubin ◽

Elena Cherepetskaya ◽

Alexander Karabutov

Keyword(s):

Ultrasonic Imaging ◽

Tomographic Imaging ◽

Current Paper ◽

Laser Ultrasonic ◽

Biological Objects ◽

Current State ◽

State Of Art

The current paper reviews a set of principles and applications of photoacoustic and laser ultrasonic imaging, developed in the Laser Optoacoustic Laboratories of ILIT RAS, NUST MISiS, and ILC MSU. These applications include combined photoacoustic and laser ultrasonic imaging for biological objects, and tomographic laser ultrasonic imaging of solids. Principles, algorithms, resolution of the developed methods, and related problems are discussed. The review is written in context of the current state-of-art of photoacoustic and laser ultrasonic imaging.

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