Bilayer piezoelectric/electrostrictive (P/E) dome unimorph.

We present a new type of actuator named bilayer piezoelectric/electrostrictive dome unimorph (BIPEDU), fabricated by attaching a piezoelectric-electrostrictive monolithic bilayer composites (PE-MBLC) to a metal plate. Various ratios of piezoelectric/electrostrictive (P/E) volume percent were used to form PE-MBLC. It was found that d(33)(eff) and K(eff) in PE-MBLC follow the series 2-2 composite mixing rule. However, the measured results were slightly lower than those of the calculated values because of a large difference in dielectric displacement between piezoelectric and electrostrictive layers and because the electrostrictor acts as the resistor that impedes the domain switching in piezoelectric layer during poling. In addition, we have investigated the field-induced displacement in PE-MBLC and BIPEDU actuators. In comparison, the displacement of BIPEDU actuators was much higher than that of PE-MBLC actuators. This was attributed to the good quality of bonding between ceramic and metal, which contributed to the proper stress/force transfer, as well as the metal sheet, which acted as a flextentional structure for PE-MBLC to generate more axial displacement in BIPEDU actuators. The load dependence of displacement in BIPEDU was obtained. In addition, the BIPEDU showed high reliability during the displacement cyclic testing.