Title: Piezoceramic omnidirectional transduction of the fundamental shear horizontal guide wave mode
Abstract: Ultrasonic guided waves are now routinely used in non-destructive evaluation. In plate-like structures, three fundamental modes can propagate, namely A<sub>0</sub>, S<sub>0</sub> and SH<sub>0</sub>. Most of the guided wave literature has thus far focused on the use of A0 and/or S0 because these modes are easy to generate in plate-like structures using standard piezoceramic transducers. Yet, at low frequency, A<sub>0</sub> and S<sub>0</sub> are dispersive. The consequence of dispersion is that signal processing becomes complex for long propagation distances. SH<sub>0</sub>, on the other hand, has the particularity of being the only non-dispersive guided wave mode. Omnidirectional transduction of SH<sub>0</sub> requires a rotational surface stress which cannot be easily generated using standard piezoceramic transducers. This paper presents a transducer concept based on piezoceramic patches assembled to form a discretized circle. The external diameter of the discretized circle was chosen to be half the SH<sub>0</sub> wavelength at the desired centre frequency. Finite element simulations using the Comsol Multiphysics environment showed that in a 1.6 mm aluminium plate the modal selectivity of the transducer was more than 25 dB at 100 kHz. A full transducer was built for experimental validation. The experimental modal selectivity was in the region of 20 dB.
Publication Year: 2016
Publication Date: 2016-04-08
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 4
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