Accession Number : ADA308554

Title :   Ferroelectric Ceramic/Polymer Bimorph Sensor for Strain Measurement in Laminates.

Descriptive Note : Interim rept. no. 2,

Corporate Author : UNIVERSITY COLL OF NORTH WALES BANGOR SCHOOL OF ELECTRONIC ENGINEERING AND CO MPUTER SYSTEMS

Personal Author(s) : Das-Gupta, D. K. ; Wenger, M. P.

PDF Url : ADA308554

Report Date : APR 1996

Pagination or Media Count : 26

Abstract : Work has been done by many workers in the past to investigate the bending (or flexural) piezoelectricity of poled polymer or ceramic films in the form of monomorphs or bimorphs. A single uniformly poled film when subjected to a uniform bending stress or strain will exhibit little piezoelectric effect due to the fact the average stress/strain across a cross-section of the film will tend to zero, the compressional stress/strain towards the inside of the bend cancelling with the extensional stress/strain towards the outside of the bend. The bending piezoelectric activity can be greatly enlarged by bonding the piezoelectric film to an electromechanically neutral material, thus forming a monomorph, or by bonding two piezoelectric films together to form a bimorph. Other methods used by other workers have been to produce a polarization gradient within a single piezoelectric film by an application of temperature gradients during poling or poling by electron beam irradiation. This report describes the results of investigations into the bending piezoelectricity of monomorphs and bimorphs constructed from ferroelectric composite materials of PTCa/P(VDF-TrFE) and PTCa/Epoxy. The theory of a piezoelectric bimorph acting as a cantilever is outlined and the results of the measurement of the piezoelectric strain coefficient h31 are given.

Descriptors :   *COMPOSITE MATERIALS, *LAMINATES, *STRAIN(MECHANICS), *CERAMIC MATERIALS, *FERROELECTRIC MATERIALS, STRESS STRAIN RELATIONS, POLARIZATION, POLYMERS, THIN FILMS, DEFLECTION, ELECTRON BEAMS, TEMPERATURE GRADIENTS, PIEZOELECTRIC MATERIALS, STRAIN GAGES, BONDING, ELECTRON IRRADIATION, BENDING STRESS.

Subject Categories : Ceramics, Refractories and Glass
      Laminates and Composite Materials
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE