Extraction and selective promotion of zero-group velocity and cutoff frequency resonances in bi-dimensional waveguides using the electromechanical impedance method

Keping Zhang; Ranting Cui; Yuning Wu; Lin Zhang; Xuan Zhu

doi:10.1016/j.ultras.2023.106937

Extraction and selective promotion of zero-group velocity and cutoff frequency resonances in bi-dimensional waveguides using the electromechanical impedance method

Ultrasonics. 2023 May:131:106937. doi: 10.1016/j.ultras.2023.106937. Epub 2023 Jan 27.

Authors

Keping Zhang¹, Ranting Cui², Yuning Wu¹, Lin Zhang³, Xuan Zhu⁴

Affiliations

¹ Department of Civil and Environmental Engineering, University of Utah, 110 Central Campus Drive, Salt Lake City, UT 84112, USA.
² College of Civil Engineering and Architecture, Guangxi University, 100 University Road, Nanning, Guangxi 530004, People's Republic of China. Electronic address: rantingcui@gxu.edu.cn.
³ Media Lab, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
⁴ Department of Civil and Environmental Engineering, University of Utah, 110 Central Campus Drive, Salt Lake City, UT 84112, USA. Electronic address: xuan.peter.zhu@utah.edu.

PMID: 36764065
DOI: 10.1016/j.ultras.2023.106937

Abstract

This study showcases the electromechanical impedance (EMI) technique for extracting and promoting zero-group velocity (ZGV) and cutoff frequency resonances in a waveguide structure. We identify the mechanisms of multiple resonances in the EMI spectra via a wave propagation perspective. Both simulation and experiments reveal the fact that sharp resonances in the conductance spectra are associated with either ZGV or cutoff frequency points. Consequently, we design four test configurations to enhance local resonances by aligning induced motions with considered mode shapes. Reasonable agreement between simulation and experiment results is observed. We evaluate the performance of considered configurations in terms of mode enhancement, and configurations that can selectively promote certain mode families are summarized. This study also shines the light on the EMI technique for quantitative non-destructive evaluation (NDE) by potentially supporting the inverse characterization of mechanical properties of host structures.

Keywords: Cutoff frequency resonance; EMI; Mode enhancement; Mode selection; NDE; Zero-group velocity modes.