Acoustic Transduction - Materials and Devices, Period 31 July 1996 to 31 December 1997, Annual Report. Volume 8.
Abstract
The overarching project objective is the development of acoustic transduction materials and devices of direct relevance to Navy needs and with application in commercial products. The initial focus of studies is upon high performance sensors and high authority high strain actuators. This objective also carries the need for new materials, new device designs, improved drive and control strategies and a continuing emphasis upon reliability under a wide range of operating conditions. In Material Studies, undoubtedly major breakthroughs have occurred in the ultra- high strain relaxor ferroelectric systems. Earlier reports of unusual piezoelectric activity in single crystal perovskite relaxors have been amply confirmed in the lead zinc niobate : lead titanate, and lead magnesium niobate : lead titanate systems for compositions of rhombohedral symmetry close to the Morphotropic Phase Boundary (MPB) in these solid solutions. Analysis of the unique properties of 001 field poled rhombohedral ferroelectric crystals suggests new intrinsic mechanisms for high strain and carries the first hints of how to move from lead based compositions. A major discovery of comparable importance is a new mode of processing to convert PVDF:TrFE copolymer piezoelectric into a relaxor ferroelectric in which electrostrictive strains of 4% have been demonstrated at high fields. Both single crystal and polymer relaxors appear to offer energy densities almost order of magnitude larger than in earlier polycrystal ceramic actuators. Transducer Studies have continued to exploit the excellent sensitivity and remarkable versatility of the cymbal type flextensional element. Initial studies of a small cymbal arrays show excellent promise in both send and receive modes, and larger arrays are now under construction for tests at ARL. New studies in constrained layer vibration damping and in flow noise reduction are yielding exciting new results.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1998
- Accession Number
- ADA353878
Entities
People
- Kenji Uchino
Organizations
- Pennsylvania State University