In-plane torsion of discal piezoelectric actuators with spiral interdigitated electrodes

• Piezoelectric disks with spiral interdigitated electrodes (SIDEs) are proposed to produce in-plane torsional displacements.
• Two typical types of the SIDEs are designed and studied with theoretical analyses, finite element simulations, and experimental tests.
• The experimental results show an excellent overall performances of the proposed actuators, especially SIDEs with constant pitch.

Piezoceramic disks with spiral interdigitated electrodes (SIDEs) on their surfaces are proposed to produce in-plane torsion. With constant electrode spiral angle (Type I) and constant pitch between adjacent electrodes (Type II), two typical types of the SIDEs are developed and studied. Working principles of the discal piezoelectric actuators are explained and their static in-plane torsional deformations are formulated. Finite element simulations are used to investigate the static and dynamic properties of the actuators. Non-ideal distributions of electric fields appear serious suppressions on the actuating abilities, even worse for Type I actuator. Due to unsymmetric piezoelectric strains in the thickness direction, bending deformations of the disks are inevitable. Prototype actuators with fixed boundary at the radius of 12 mm are fabricated and tested. With a driving voltage of 400 Vp-p at 1 Hz, the maximum quasi-static in-plane torsional angles are 0.00458° for Type I actuator and 0.00605° for Type II actuator at the radius of 6 mm. With a driving voltage of 10 Vp-p, the vibration amplitudes at the radius of 6 mm are 0.00105° at 86.0 kHz for Type I actuator and 0.00149° at 84.4 kHz for Type II actuator at the first in-plane torsional vibration modes.