Membrane Piezoelectric MDS Actuator with a Flat Double Helix of Interacting Electrodes

Abstract

A schematic diagram and mathematical model of the functioning of a new piezoelectric membrane (MDS) actuator with double spirals (DS) electrodes on the upper and/or lower surfaces of a thin piezoelectric layer with axisymmetric and periodic (small period) reciprocal electric polarization along the radial coordinate are presented. The polarization of the layer is carried out as a result of connecting the polarizing value of the electrical voltage to the outputs of the double spirals of the electrodes. The electrodes of each (upper and lower) double helix of the MDS actuator are made in the form of electroded tape coatings on the surfaces of the piezoelectric layer in close proximity to each other (due to the small pitch of the helix) to create high electric field strengths along the field lines in local areas of the piezoelectric layer between them when connecting an alternating or direct control electrical voltage to the electrodes, in particular, with positive and negative values of electrical potentials. It is important that the electric field lines and, as a consequence, the polarization of the piezoelectric layer of the MDS actuator are oriented mainly along (i.e., towards or against) the radial coordinate of the membrane, in contrast to many traditional actuator schemes. The results of numerical simulation for a round elastic membrane with piezoelectric actuators installed on its upper and lower surfaces confirmed the effectiveness of the proposed piezoelectric MDS actuator when operating according to the “bimorph” scheme, including using the proposed new structural element (section) - piezoelectric MDS- “compression rings” for various geometric and control parameters. The effect of a significant increase in the deflection of the membrane with installed piezoelectric MDS actuators was revealed compared to the use of traditional homogeneous plate piezoelectric actuators of the bimorph type for various conditions of fastening the membrane, in particular, stationary (rigid) fastening of its center. For a hybrid piezoelectric MDS actuator, including independent concentric circular and annular (i.e., “pressure ring”) sections, a non-monotonic character was revealed and a numerical analysis was carried out of the nonlinear dependence of the largest deflection in the center of a membrane hinged and fixed at the edge on the radius ratio its circular and annular MDS sections. Cases have been identified in which the “pressure ring” effect manifests itself, i.e. when the maximum deflection of a membrane with a “pressure ring” exceeds the best possible deflection of this membrane without using it according to the traditional “bimorph” scheme. The new piezoelectric MDS actuator can be used in micromechanics, controlled optics, sensor technology, acoustics, in particular, in the manufacture of piezoelectric acoustic or membrane-type sensor elements, electromechanical transducers for collecting vibration energy.