Abstract
High frequency guided-waves offer a trade-off between the high sensitivity of local bulk ultrasonic thickness measurements and the large area scanning of lower frequency guided-waves, so it has been a growing interest for corrosion inspection with the dispersive SH1 mode. However, according to the dispersive curve, it is hard to generate the pure SH1 mode since the non-dispersive SH0 mode will be excited simultaneously. Thus, this paper investigates a transducer design method to generate a pure SH1 guided-wave, where the dual periodic-permanent-magnet electromagnetic acoustic transducers (PPM EMATs) are placed on exactly opposite positions either side of the plate symmetrically. The suppression effect for SH0 and the enhancement effect for SH1 of the dual PPM EMATs are mainly discussed by theoretical analysis and simulation analysis, and the influence of positioning errors of PPM EMATs placed on opposite sides of the plate on its performances are analyzed. Employing the proposed dual PPM EMATs, some experiments are performed to verify the reliability of finite element simulation. The results indicate that the dual PPM EMATs can suppress the SH0 mode and generate the pure SH1 mode effectively. Moreover, the longitudinal and lateral positioning errors can affect the dual PPM EMATs performances significantly.
Highlights
Nowadays the local bulk ultrasonic thickness measurements [1] and the low frequency guided-waves [2] have been proven to be efficient for corrosion damage inspection
As a compromise choice of the above two methods, the high frequency guided-waves is presented for corrosion inspection which can improve the detection sensitivity of guided-waves at the cost of scanning regions
Wave packet separation phenomenon between SH0 mode and SH1 mode can be seen in red signals and blue signals, but only pure SH1 wave packet exists in green signals
Summary
Nowadays the local bulk ultrasonic thickness measurements [1] and the low frequency guided-waves [2] have been proven to be efficient for corrosion damage inspection. The former has high detection sensitivity, small scanning region and long detection period, and the latter can scan large areas rapidly for big defects with lower detection sensitivity. Richard [19] approximated pipes as planar waveguides and analyzed the detectability of corrosion damage with S0, SH0, and SH1 mode, respectively, and demonstrated the potential of high frequency short-range guided-waves detection technique.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
