4 January 2008 Numerical simulation of surface crack detection by laser-generated circumferential guided wave in elastic cylinders
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Nondestructive and non-contact detection methods of surface defects of the elastic cylinders are urgently needed especially for the extensive application of such structure in the manufacture and daily life. In recent years there has been an increasing focus on laser ultrasonics, a novel technique in nondestructive evaluation, which can excite and receive high frequency ultrasonic waves from distance range in thermoelastic regime. This paper utilized the finite element method to investigate the transient mode conversion of circumferential guide waves by the surface crack of cylinder. The numerical model of the ultrasonic waves generated on aluminum cylinder whose diameter is 10mm by pulsed laser is established, considering the dependence of the material parameters on the temperature varying. The depth of the surface crack varies from 100 μm to 1 mm, which is much less comparing with the wavelength of the circumferential guide waves. The numerical results obtained from finite element model are presented in terms of vertical displacement, which is generated because of the localized temperature gradient on the surface. And the signals of the circumferential guide waves are analyzed by wavelet transformation. From the obtained results we can see that the amplitude of the scattered waves induced by the crack become more and more obvious as the depth of the crack increases and the time-frequency distributions of the scattered waves also change obviously. The results demonstrate the propagation of the circumferential guide waves on the surface of the cylinder can be applied in crack detection well.
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Yifei Shi, Yifei Shi, Zhonghua Shen, Zhonghua Shen, Xiaowu Ni, Xiaowu Ni, Jian Lu, Jian Lu, } "Numerical simulation of surface crack detection by laser-generated circumferential guided wave in elastic cylinders", Proc. SPIE 6825, Lasers in Material Processing and Manufacturing III, 682512 (4 January 2008); doi: 10.1117/12.754307; https://doi.org/10.1117/12.754307

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