Membrane piezoelectric MDS-actuator with a flat double spiral of interacting electrodes

A schematic diagram and mathematical model of functioning of a new piezoelectric membrane (MDS) actuator with double spiral (DS) electrodes on the upper and/or lower surfaces of a thin piezoelectric layer with axisymmetric and periodic (with a small period) in radial coordinate mutual reversed electric polarization are presented. The polarization of the layer was realized as a result of connecting the polarizing electric voltage of the appropriate value to the outputs of the double spirals of the electrodes. The electrodes of each (upper and lower) double spiral of the MDS-actuator are made in the form of electrodeposited ribbon coatings on the surfaces of the piezoelectric layer in close proximity to each other (due to the small spiral pitch) to create high values of electric field strength along the lines of force in localized areas of the piezoelectric layer between them when an alternating or constant control electric voltage is connected to the electrodes, in particular, with positive and negative values of the electrical potentials. Importantly, the electric field force 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 conventional actuator schemes. The results of numerical modeling for a circular elastic membrane with piezoelectric actuators installed on its upper and lower surfaces confirmed the effectiveness of the proposed piezoelectric MDS-actuator when it functions according to the “bimorph” scheme, including the use of the proposed new structural element (section) – a piezoelectric “compression ring” MDS at various geometric and control parameters. The effect of a significant increase in the membrane deflection with installed piezoelectric MDS-actuators compared to the use of traditional homogeneous plate piezoelectric actuators of bimorph type for different conditions of the membrane fixation, in particular, stationary (rigid) fixation of its center is revealed. For a hybrid piezoelectric MDS-actuator including independent concentric round and circular (i.e. “compression ring”) sections, the non-monotonic nature and numerical analysis of the nonlinear dependence of the largest deflection at the center of a hinge-immobile membrane fixed at the edge on the ratio of the radii of its round and circular MDS sections were revealed. The cases in which the effect of the “compression ring” is manifested, i.e. when the maximum deflection of a membrane with the “compression ring” exceeds the best possible value of the deflection of this membrane without its use in the traditional “bimorph” scheme, are identified. The new piezoelectric MDS-actuator can be used in micromechanics, controlled optics, sensor technology, acoustics, in particular, in the manufacture of piezoelectric acoustic or sensor elements of membrane type, electromechanical transducers for vibration energy collection.