Complex electromechanical coefficients of piezoelectric composites: Applications to passive vibration damping
A modified resonance technique was used to measure the complex electromechanical property coefficients of lossy 0-3 composite samples comprised of ceramic lead zirconate titanate (PZT) powder dispersed in different polymer matrices. An increase in the loss tangents of the dielectric, elastic and piezoelectric coefficients was observed near the glass transition temperatures of the polymer phases. In the case of a PZT-polyvinylidene fluoride (PVDF) composite, it was possible to measure the electromechanical coefficients using 31 and thickness mode resonances over a range of temperature spanning the glass transition temperature of the polymer. The principle of time-temperature superposition was used to explain the frequency and temperature dependences of the coefficients. The relaxation behavior of the properties of 0-3 composites, predicted theoretically by a simple cubes model representing the composite structure, was found to be in partial agreement with the experimental data. Due to electromechanical coupling, an imaginary part in a corresponding elastic coefficient which in turn implies lossy mechanical behavior. A dissipative mechanism like electrical conductivity in a piezoelectric material results in a mechanical loss tangent and associated dissipation of mechanical energy and damping of mechanical vibrations. This concept of passive piezoelectric damping was developed and the effect of internal conductivity simulated by connecting external resistors across poled piezoceramic elements with large piezoelectric coupling. The damping characteristics of a stack specimen comprised of several such elements were optimized. The properties measured using electrical resonance and mechanical vibration experiments agreed with predictions from theory. It was possible to obtain a large mechanical stiffness coefficient ([approximately]5 to 10 x 10[sup 10] N/m[sup 2]) along with a large mechanical loss tangent ([approximately]0.30).
- Research Organization:
- Pennsylvania State Univ., University Park, PA (United States)
- OSTI ID:
- 6931612
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COMPOSITE MATERIALS
DAMPING
ELECTRICAL PROPERTIES
MAGNETOSTRICTION
PZT
ELECTROMECHANICS
MECHANICAL VIBRATIONS
PIEZOELECTRICITY
POLYMERS
ELECTRICITY
LEAD COMPOUNDS
MAGNETIC PROPERTIES
MATERIALS
MECHANICS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
TITANATES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
ZIRCONATES
ZIRCONIUM COMPOUNDS
360606* - Other Materials- Physical Properties- (1992-)
360204 - Ceramics
Cermets
& Refractories- Physical Properties