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A semi-analytical approach for SH guided wave mode conversion from evanescent into propagating
1Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang, Jiangsu, China; Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, USA.
Ultrasonics
|December 19, 2017
Summary
This study demonstrates converting evanescent shear horizontal (SH) waves into propagating waves using a narrow aperture. Conversion efficiency is quantified using a semi-analytical form and finite element analysis, revealing frequency and aperture dependence.
Area of Science:
- Solid Mechanics
- Wave Propagation
- Acoustics
Background:
- Evanescent shear horizontal (SH) waves are non-propagating wave modes.
- Efficient conversion of these modes is crucial for various applications in material science and engineering.
Purpose of the Study:
- To present a method for converting evanescent SH guided waves into propagating waves.
- To develop a simple, compact form for conversion efficiency.
- To quantify the conversion efficiency using theoretical and numerical methods.
Main Methods:
- Prescribing time-harmonic SH evanescent displacement on a narrow aperture at a plate edge.
- Utilizing a semi-analytical form based on the complex reciprocity theorem.
- Employing two-dimensional (2-D) finite element analysis (FEA).
Main Results:
- A simple, compact formula for conversion efficiency is derived.
- Conversion efficiency is quantified using a semi-analytical form and FEA.
- Power flow analysis shows complex-valued power, with real and imaginary parts linked to propagating and evanescent modes, respectively.
Conclusions:
- The conversion efficiency and converted modes are controllable via aperture geometry and excitation frequency.
- This work provides a theoretical and numerical framework for understanding and optimizing evanescent to propagating SH wave conversion.
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