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Article

Detection and Quantification of Damage in Metallic Structures by Laser-Generated Ultrasonics

College of Mechanical Engineering &The State Key Lab of Fluid Power Transmission and Control, Zhejiang University, Hangzhou 320027, China
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Appl. Sci. 2018, 8(5), 824; https://doi.org/10.3390/app8050824
Received: 23 April 2018 / Revised: 16 May 2018 / Accepted: 17 May 2018 / Published: 20 May 2018
The appearance of damage on metallic structures is inevitable due to complex working environments. Non-destructive testing (NDT) of these structures is critical to the safe operation of the equipment. This paper presents a non-destructive damage detection, visualization, and quantification technique based on laser-generated ultrasonics. The undamaged and damaged metallic structures are irradiated with laser pulses to produce broadband input ultrasonic waves. Damage to the structures plays the role of a nonlinear radiation source of new frequencies. Usually these new frequencies are too weak to be detected directly. Here, the state space predictive model is proposed to address the problem. Based on the recorded responses in the time domain, the state space attractors are reconstructed. Damage to the structures is shown to change the properties of the attractors. A nonlinear damage detection feature called normalized nonlinear prediction error (NNPE) is extracted from the state space to identify the changes in the attractors—and hence the damage. Furthermore, the damage is visualized and quantified using the NNPE values extracted from the entire area by using a laser scanning technique. Experimental results validate that the proposed technique is capable of detecting, visualizing and quantifying artificial damage to aluminum alloy plates and actual fatigue cracks to a twin-screw compressor body. View Full-Text
Keywords: damage detection; damage quantification; laser-generated ultrasonics; state space reconstruction; normalized nonlinear prediction error damage detection; damage quantification; laser-generated ultrasonics; state space reconstruction; normalized nonlinear prediction error
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MDPI and ACS Style

Liu, Y.; Yang, S.; Liu, X. Detection and Quantification of Damage in Metallic Structures by Laser-Generated Ultrasonics. Appl. Sci. 2018, 8, 824. https://doi.org/10.3390/app8050824

AMA Style

Liu Y, Yang S, Liu X. Detection and Quantification of Damage in Metallic Structures by Laser-Generated Ultrasonics. Applied Sciences. 2018; 8(5):824. https://doi.org/10.3390/app8050824

Chicago/Turabian Style

Liu, Yongqiang, Shixi Yang, and Xuekun Liu. 2018. "Detection and Quantification of Damage in Metallic Structures by Laser-Generated Ultrasonics" Applied Sciences 8, no. 5: 824. https://doi.org/10.3390/app8050824

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