The strain response of ferroelectric multilayer actuators under combined action of electric field and uniform load

The strain response of lead zirconate titanate piezoelectric multilayer actuators have been measured within the 10/sup 7/ N/m/sup 2/ stress and the 3.10/sup 6/ V/m periodic unipolar driving voltage and an extra nonstationary strain component is detected. General remarks on this nonstationary behavior are made in terms of the dielectric relaxation and the space charge effects as well.