Boonsang, Siridech
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Preferred name
Boonsang, Siridech
Alternative Name
Boonsang, S.
Main Affiliation
Email
siridech.bo@kmitl.ac.th
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Item type:Publication, Signal enhancement in Rayleigh wave interactions using a laser-ultrasound/EMAT imaging system(2005-06-01); Dewhurst, R. J.Enhancement of signal amplitudes from Rayleigh wave interaction at solid surface features has been investigated when signals were detected by an in-plane electromagnetic acoustic transducer (EMAT). A laser-ultrasound system was used to inspect surface-breaking slots, serving as artificial defects. Nd:YAG laser pulses were delivered onto a metal surface via an optical fiber and focused to a line source by a cylindrical lens. An in-plane EMAT receiver detected transient surface acoustic waves. A-scan signals and B-scan images from surface defects revealed increased signal amplitude up to 2.8 ± 0.3 depending on the distance of the transducer from a slot. An explanation is based on the interaction of the EMAT sensor with the Rayleigh wave. A supporting computer model was derived to show that experimental signal enhancements were consistent with numerical predictions. © 2005 Elsevier B.V. All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Modelling of magnetic fields to enhance the performance of an in-plane EMAT for laser-generated ultrasound(2006-12-22); Dewhurst, R. J.A new magnetic arrangement is described for use with an in-plane electromagnetic acoustic transducer (EMAT) for detecting laser-generated ultrasound. The magnetic flux density was modelled and validated. Modelling was accomplished in 3D using finite element software to predict new magnet spatial distributions. A configuration was found which increased the magnetic flux density by a factor of 1.8 ± 0.2, compared to magnetic configurations previously used in conventional designs. Model predictions were implemented and confirmed experimentally. As a result, laser ultrasound Rayleigh waves have been used to verify the performance of this sensor system. It was establish that the EMAT's in-plane sensitivity increased, while the frequency bandwidth improvement factor was about 1.9 ± 0.2. The resonant frequency increased from 6.5 MHz and 16.4 MHz, with both exhibiting an extended frequency response well beyond the resonant values. For maximum frequency response, it was demonstrated that added elements such as cables may have a deleterious effect. In particular the length of the cable, which in turn adds capacitance to the overall circuit, will decrease the frequency response of the EMAT. The frequency response was compared with a previous sensor, to provide an increased resonant frequency factor of 2.5 ± 0.2. © 2006 Elsevier B.V. All rights reserved.