Experimental study of unconveniant static and dynamic deformations of piezoelectric actuators

Piezoelectric actuators are widely used active devices able to perform static and dynamic displacements in the micrometer and submicrometer range. Both the magnitudes and the directions of these displacements and forces applied to devices acted upon must be strictly controlled. Different actuators have been studied by using speckle interferometry. The results of the study show that some actuator designs lead to unexpected shapes of the deformed actuator. As a consequence, these actuators have an unsuitable behaviour, which may consist in uncontrolled directions of the forces applied, in unconveniant deformations of the structures acted upon, or in stress concentrations which are dangereous for the actuator itself. Several holographic and shearographic speckle interferometry techniques are used throughout the study, so as to allow separate measurement of orthogonal components of the displacement maps and an estimation of their spatial derivatives. Results of other experimental investigations show deformations which are convenient and may be used in the development of sensors and actuators.