Abstract: Methods and compositions are described for the preparation of piezoelectric ceramic-polymer composites having improved properties for application in piezoelectric devices. These composites consist of piezoelectric particles embedded in a polymer matrix. The improvements of this invention result from discoveries of the effects of particle size, particle size dispersity, volumetric loading levels, ceramic dielectric constant, and polymer dielectric constant on performance. Various improved devices based on these compositions are also described.

Abstract: An underwater sonar projector includes a one piece hollow shell of elliptical cross section having a number of transducer stacks positioned within the shell and compressively prestressed by the shell to vibrate along the major axis thereof which causes the broad surfaces between the small radius ends to vibrate in and out. To resist large external shocks the shell is made somewhat heavier than usual, a center support member or beam is placed along the minor axis of the shell and an adjustable support rod is carried in the beam which is adjusted to a length just sufficient to clear the vibrating surfaces of the projector in normal operation but which functions to limit the inward movement of the shell if exposed to an explosion. The transducer stacks include a number of columns of piezoelectric disks on each side of the support beam which are bonded together, each stack having a tail member fastened to said center support beam and a head member between the disks and the end of the shell.

Abstract: An underwater sonar transducer includes a centrally located beam with a plurality of stacks of piezoelectric transducer elements extending from each side, with a rigid end beam at the opposite end of each stack. A plurality of bolts extending from one end beam to the other on opposite sides of the stacks are tightened to apply a desired amount of prestress on the ceramic stacks. Arcuate radiating elements are welded to opposite sides of each end beam, end cap members are fastened to the centrally located beam at each end of the transducer and a jacket of elastomeric material is bonded to the edges of the end cap members to prevent ingress of fluid into the piezoelectric elements. Energizing of the piezoelectric elements causes expansion and contraction of the stacks, pushing the end beams in and out and causing bowing of the radiating elements to project sonar energy.

Abstract: A flexural disk transducer includes two thickness poled piezoelectric disks each of which is bonded on one side to a metal backing plate of substantial thickness and on the other side to a thin metal "skin" or plate. The metal backing plates are, in turn, bonded to a ring-shaped metal spacer member having a rectangular "C" shaped cross section with the axially extending web made sufficiently thin and the radially extending flanges grooved such that the spacer member is sufficiently compliant that it has minimal effect on the resonant frequency of the disks. The disks are coated on each side with a thin layer of conducting material such as silver or copper and have radially extending wires serving as connections to such layers. The entire assembly is contained within a handling ring with the wire connections and the space between the assembly and the handling ring filled with electrical potting material. A thin layer of neoprene rubber covers the exposed faces of the disks for waterproofing.