Performance test and improvement of piezoelectric torsional actuators

Abstract

This paper presents the design, test and improvement of a newly developed piezoelectric torsional actuator which generates large angular displacement using piezoceramics and a torsion bar. Because the proposed piezoelectric torsional actuator can generate torsional displacement, directly invoking the shear mode of the piezoelectric material, no complicated additional mechanism is needed. The electrodes are formed from a cylindrical piezoceramic poled along the axial direction and divided into six segments that are arranged radially and bonded to each other in opposite poling directions with conductive adhesive. The key to designing such an actuator is to match the torsional resonant frequency of the actuator with the excitation frequency. Finite element analysis for the piezoelectric actuator is performed to find the torsional resonant mode; an experimental investigation in terms of electrical impedance and torsional displacement measurement was conducted to verify the mode. As a result a maximum angular displacement of 0.18° was measured. To magnify the torsional displacement, a torsion bar was attached on top of the actuator. Thus, the torsional displacement was magnified by a factor of three. A resonance decrease due to the added mass of the torsion bar was observed and a theoretical investigation was performed using a two degrees of freedom lumped model.

Hierarchically buckled sheath-core fibers for superelastic electronics, sensors, and muscles

“…The amount of inserted twist was far below the amount needed to provide coiling (22). The twisted fiber geometry in our fabrication provides torsional actuators with a torsional stroke per muscle length up to 104 times the value previously demonstrated for electrically driven, nonthermal, nonelectrochemical muscle fibers (29,30). It avoids the Carnot efficiency limit of thermally powered artificial muscles and the use of liquids or vapors for electrochemically or absorption-powered muscles (31)(32)(33).…”

Torsional Strain ofTaS3Whiskers on the Charge-Density Wave Depinning

“…The torsional deformation appears to couple with nonuniform CDW deformation; it reveals surface pinning and development of a polar axis along the chains direction (the longer dimension of the whisker)-the c axis, likely due to a ferroelectric-or ferroelastic-type transition. Up to our knowledge, we demonstrate the first torsional actuator, in which the torque is the intrinsic property of the working element: it is not achieved by special configuration of elements ( [12] and Refs. therein) or an external force ( [13] and Refs.…”

Electromechanical Actuator Ribbons Driven by Electrically Conducting Spring‐Like Fibers

“…The number of revolutions and rotary speed over time had been obtained through a frame‐by‐frame analysis (Figure S11, Supporting Information). When a pulse current (40 mA and 2 Hz) was passed through a left‐handed SLF twisted from 20 CNT fibers, an anticlockwise rotary actuation of 135 revolutions per meter had been generated within 250 ms, three orders of magnitude higher than the torsional actuators based on shape memory alloys, conducting polymers, and piezoelectric ceramics . In particular, the rotation output is 200 times higher than that of a single‐ply CNT fiber .…”