Various Types of Piezomechanics Systems: Their Regimen and Experimental Analysis

The layered piezoactuators used in mechanisms requiring high precizion displacements have indicated that accuracy depends on design and technological factors. One of essential requirements for compound piezoactuators is their capability of transferring unipolar or bipolar force. In the first version, the piezoactuators acting in one direction is made of separate piezoelements and adapted binding materials. They operate under positive deformation (elongation due to neutral position) when the applied voltage is positive to polarity. The layered piezoactuators returns to its initial position under negative deformation (contraction) when the polarity voltage is applied opposite. The piezoactuators deformation in this direction only due to small forces of binding materials. When the piezoceramic is deformed by an external electric field, the input electrical energy is larger than the output mechanical energy. The ineffective electrical energy is stored as electrostatic energy in the piezostack and reverts to the power supply in the final process of an operating cycle. The efficiency is determined only by the loss such as hysteresis in the strain curve. The electromechanical feedback affects the correction of the hysteresis. It is evident that by applying the electromechanical feedback the hysteresis can be corrected up to 0.2% from the maximum displacement.