Types of Oscillations of Piezoelectric Elements
All main types of oscillations can be excited in piezoelectric elements:
- longitudinal, along length, width, and thickness,
- bending oscillations along width and thickness,
- radial oscillations,
- shear oscillations along thickness,
- mechanical harmonics (overtones) of the main oscillation types.
In the general case, a piezoelectric element will have multiple resonant frequencies. However, the choice of the geometry of the piezoelectric element and its electrodes makes it possible to obtain a relatively pure (single-frequency) spectrum in a specified frequency range.
| TYPE OF OSCILLATION | DEFORMATION CHARACTER | FREQUENCY RANGE, kHz |
| Longitudinal along length and width |  |
50 ÷ 150 |
| Bending along thickness |  |
1 ÷ 10 |
| Bending along width |  |
10 ÷ 60 |
| Radial oscillations |  |
150 ÷ 700 |
| 1st overtone of radial oscillations |  |
600 ÷ 1000 |
| Shear along thickness |  |
800 ÷ 7000 |
| Longitudinal along thickness energy trapping |
 |
3000 ÷ 30000 |
| 1st overtone of thickness oscillations |  |
3000 ÷ 60000 |
The classification given in the table is not strict. The frequency range boundaries for each type of oscillation may be shifted in one direction or the other depending on the physical constants of the piezoceramic material used, as well as on the design features of the piezoelectric elements and the technological capabilities of manufacturing.
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