Piezoelectric-Electrostrictive Monolithic Bi-Layer Composite Flextensional Actuator.

We propose a new type of flextensional actuator comprised of an electcomechanically active element which is a piezoelectric-electrostrictive monolithic bi-layer composite (PE-MBLC) capped by truncated thin brass sheets. The PE-MBLC contains equal amounts of 0.65 {Pb(Mg1/3Nb2/3) O3}-0.35PbTiO3 and 0.9{Pb(Mg1/3Nb2/3)O3}-0.1PhTiO3 by volume, and is obtained by a co-sintering process. With applied Emax = 10 kV/cm unipolac drive, the maximum axial displacement (u33) produced by the uncapped and capped PE-MBLC is 11 and 21 μm, empectively. The hysteresis in unipolar u33 at 0.5 Emax is 4.6% for the uncapped PE-MBLC, while that for the capped one is 11%. Under bipolar excitation, the maximum u33 for uncapped is 11.6 μm at +Emax and 6.6 μm at -Emax with as asymmetry factor (ξ) of 1.75 for which u33 < 0 for all E < 0. Under bipolar exsitation, the maximum u33 at +Emax for the capped PE-MBLC is 19 μm while that for -Emax is 8 μm with ξ = 2.4, for which u33 > 0 at -Emax but is smaller than the u33 at +Emax. The origins of the observed asymmetry in u33 are discussed in the context of symmetry superposition and deformation mechanics of the endcaps. [ABSTRACT FROM AUTHOR]