The Application of Laser-Generated Ultrasound Technology in Coating-Substrate Systems

Abstract:

Based on thermo-elastic regime, ultrasound can be generated by modulated laser pulse. When laser-generated ultrasound technology is applied to measure the thickness of coating and study the coating characters, even analysis the effects of coating during detecting the cracks and voids of the substrate, it is shown that it’s a very efficiency technology. When measuring the coating thickness, it can control the accuracy scope at the nanoscale; the relative error is under 2% for single layer coating, under 10% for double layer coating. As to coating characters, for example, Young modulus, Poisson's ratio etc, according to BP Neural network algorithm, use the nonlinear map relationship between material parameter and laser generated ultrasound wave forms to get these coating characters reversal. Studying the dispersion characteristic of the coating-substrate system can analysis effects of coating to defects detecting that coating absorbs large energy which leads to faster heat conduction speed than uncoated sample, but have smaller surface wave amplitude. All these are shown that laser-generated ultrasound technology can realize high-precise measurement and have an extensive use in the field of nondestructive testing.

• Periodical: Applied Mechanics and Materials (Volume 868)
• Pages: 139-150
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.868.139
• Online since: July 2017
• Authors: Zhi Xiang Xu, Hai Yang Guo
• Keywords: BP Neural Net, Coating-Substrate, Laser Ultrasound, Thermo-Elastic, Thickness

References

[1] R.M. White, Generation of elastic waves by transient surface heating, J. Appl. Phys. 34 (1963)3559–3564.

[2] G. Birnbaum, G.S. White, Laser techniques in NDE, in: R.S. Sharpe (Ed. ), Research Techniques in Nondestructive Testing, Academic Press, New York, (1984).

[3] D.A. Hutchins, R. J. Dewhurst, S. B. Palmer, Laser generation as a standard acoustic source in Meta, Appl. Phys. Lett. 38 (1981) 677–679.

DOI: 10.1063/1.92476

[4] C.B. Scruby, L.E. Drain, Laser Ultrasonics: Techniques and Applications, Adam Hilger, Bristol, 1990, p.76.

[5] S.J. Davies, C. Edwards, G.S. Taylor, et al., J. Phys. D: Appl. Phys. 26 (1993) 329–348.

[6] Y. Hong, S. D. Sharples, M. Clark, et al., Rapid and accurate analysis of surface and pseudo-surface waves using adaptive laser ultrasound techniques, Ultrasonic 42 (2004) 515-518.

DOI: 10.1016/j.ultras.2004.01.046

[7] A. Moura, A.M. Lomonosov, P. Hess, Depth evaluation of surface-breakingcracks using laser-generated transmitted Rayleigh waves, J. Appl. Phys. 103 (2008) (Art. No: 084911).

DOI: 10.1063/1.2910897

[8] S. Yashiro, J. Takatsubo, H. Miyauchi, et al., A novel technique for visualizing ultrasonic waves in general solid media by pulsed laser scan, NDT&E Int. 41 (2008) 137–144.

DOI: 10.1016/j.ndteint.2007.08.002

[9] Karabutov AA, Podymova NB. Quantitative analysis of the influence of voids and delaminations on acoustic attenuation in CFRP composites by the laser- ultrasonic Spectroscopy method. Compos Part B: Eng 2014; 56: 238–44.

DOI: 10.1016/j.compositesb.2013.08.040

[10] Jijun Wang, Zhonghua Shen, Ã Numerical simulation of laser-generated surface acoustic waves in the transparent coating on a substrate by the finite element method [J]. Optics & Laser Technology 39 (2007) 21–28.

DOI: 10.1016/j.optlastec.2005.05.015

[11] Baiqiang Xu etc, Thermal and mechanical finite element modeling of laser-generated ultrasound in coating–substrate system[J]. Optics & Laser Technology 38 (2006) 138–145.

DOI: 10.1016/j.optlastec.2004.12.002

[12] R.E. Challis, U. Bork, P.C.D. T Odd. Ultrasonic NDE of adhered T-joints using Lamb waves and intelligent signal Processing, Ultrasonies1996 34 455-49.

DOI: 10.1016/0041-624x(95)00115-j

[13] B. Sadoun, An emcient simulation scheme for testing materials in a nondestructive manner. Information Science 2001 137 43-51.

DOI: 10.1016/s0020-0255(01)00113-x

[14] Jijun Wang, Zhonghua Shen, etc, Numerical simulation of laser-generated surface acoustic waves in the transparent coating on a substrate by the finite element method. Optics & Laser Technology 39 (2007) 21–28.

DOI: 10.1016/j.optlastec.2005.05.015

[15] Wu L, Cheng JC, Zhang SY. Mechanisms of laser-generated ultrasound in plates. J Phys D Appl Phys 1995; 28: 957–64.

[16] Xu, Baiqiang Numerical modeling of laser ultrasound in Layered systems using finite element method and determination the materials Parameters using the neural networks [D]. Nanjing. University of Science & Technology.

[17] B. Boashash, Note on the use of the Wigner distribution for time frequency signal analysis, IEEE transaction on acoustics, speech, and signal Processing, 1988, 36(9): 151-1521.

DOI: 10.1109/29.90380

[18] Simon Haykinetc, The comprehensive basis of the neural network, the first l edition . Beijing Tsinghua university press, (2001).

[19] Martain T. Hagan. Howard B. Demuth mark H. Beale etc, Neural network design, a Beijing machinery industry press (2002).

[20] Xu, Dong, Wu, Zheng, Based on MATLAB6. X system analysis and design, a xi an- xi an university of electronic science and technology press, (2002).