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Analysis of spurious bulk waves in ball surface wave device
Satoru Ishikawa1, Hideo Cho, Yusuke Tsukahara
1Department of Materials Processing, Tohoku University, Aoba 02 Aramaki Aoba-ku, Sendai 980-8579, Japan.
Ultrasonics
|December 5, 2002
Summary
This study guides the design of non-destructive evaluation (NDE) apparatus and ball surface acoustic wave (SAW) devices by analyzing acoustic wave propagation in spheres. Findings indicate in-plane stress is crucial for optimizing SAW devices.
Area of Science:
- Acoustics
- Materials Science
- Surface Acoustic Waves
Background:
- Surface acoustic waves (SAW) on spheres offer diffraction-free propagation, valuable for device design.
- Understanding acoustic wave behavior in spherical geometries is key for advanced NDE and SAW applications.
Purpose of the Study:
- To provide design guidelines for non-destructive evaluation (NDE) apparatus and ball SAW devices.
- To analyze acoustic wave propagation in spheres, focusing on SAW behavior and bulk wave interference.
- To compare acoustic wave excitation under different stress conditions (out-of-plane vs. in-plane).
Main Methods:
- Calculated laser-generated acoustic displacements under ablation and thermoelastic conditions.
- Experimentally verified the accuracy of acoustic displacement calculations.
- Compared acoustic waves excited by out-of-plane and in-plane stresses on spherical surfaces.
Main Results:
- Out-of-plane stress generated higher relative amplitudes and more bulk waves compared to in-plane stress.
- The ratio of bulk wave amplitude (out-of-plane vs. in-plane) was 3.1:1 at 90 degrees and 1.67:1 at 0 degrees.
- SAW waveforms remained similar regardless of the applied stress type.
Conclusions:
- For ball SAW devices, selecting piezoelectric materials and interdigital transducer designs that favor in-plane stress is essential.
- Optimizing stress conditions can enhance the performance and reduce interference in spherical SAW devices.