Constrained thickness-shear vibration-based piezoelectric transducers for generating unidirectional-propagation SH0 wave

Jiangcheng Cai; Yuehao Du; Qianhua Kan; Qinghua Zhang; Hongchen Miao; Guozheng Kang

doi:10.1016/j.ultras.2023.107106

Constrained thickness-shear vibration-based piezoelectric transducers for generating unidirectional-propagation SH₀ wave

Ultrasonics. 2023 Sep:134:107106. doi: 10.1016/j.ultras.2023.107106. Epub 2023 Jul 11.

Authors

Jiangcheng Cai¹, Yuehao Du¹, Qianhua Kan¹, Qinghua Zhang², Hongchen Miao³, Guozheng Kang¹

Affiliations

¹ Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province, School of Mechanics and Aerospace Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China.
² School of Civil Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China.
³ Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province, School of Mechanics and Aerospace Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China. Electronic address: miaohongchen@swjtu.edu.cn.

PMID: 37467523
DOI: 10.1016/j.ultras.2023.107106

Abstract

Excitation of a pure guided wave with a controllable wavefield is essential in structural health monitoring (SHM). For example, a unidirectional-propagation guided wave can significantly reduce the complexity of signal interpretations by avoiding unwanted reflections. However, few transducers are currently capable of exciting a pure unidirectional-propagation guided wave, which cannot satisfy the emerging demands from the field of SHM. In this work, the thickness-shear vibration characteristics of the piezoelectric PZT wafer bonded on a waveguide are investigated by theoretical modeling and numerical simulations. It is found that there is a phase difference between the electric-excitation signal applied on the PZT wafer and the mechanical response signal of the bottom surface of the viscoelastic adhesive layer that connects the PZT wafer and waveguide. Moreover, such a phase difference can be adjusted by changing the equivalent width of the PZT wafer. Based on this finding, two piezoelectric transducers with different shape configurations are proposed to excite the unidirectional-propagation SH₀ wave (the fundamental shear horizontal wave). Finite element simulations and experiments are conducted to verify the performances of the two unidirectional transducers. Results show that the two transducers can excite a pure SH₀ wave and enhance the wave energy along a single direction. No time delay is required to excite the proposed transducers. Due to their simple configurations, the developed unidirectional SH₀ wave transducers will have great potential applications in SHM.

Keywords: Piezoelectric transducer; Shear horizontal waves; Structural health monitoring; Unidirectional generation.