## 3pSP2. Methods of calculating coupling coefficients for electrostrictive materials.

### Session: Wednesday Afternoon, December 4

### Time: 2:20

**Author: Harold C. Robinson**

**Location: Naval Undersea Warfare Ctr., New London Detachment, New London, CT 06320**

**Abstract:**

The definition of the coupling constant for piezoelectric ceramics is
straightforward and depends directly on the square of the piezoelectric constant
and inversely on the compliance and dielectric constants appropriate for the
boundary conditions. However, these definitions are not directly applicable to
electrostrictive materials because the material is nonlinear and therefore the
equivalent piezoelectric and dielectric constants are not universally defined.
Also, the presence of bias voltages about which the material would operate
complicates the situation dramatically. In this presentation, energy methods
[Hom et al., IEEE Trans. Sonics Ultrason. and Freq. Cont. UFFC-41, 541--545
(1994)] are used to calculate k[inf 33] for electrostrictive materials using
several different constitutive models for the material. Experimental data on PMN
taken at NUWC will be used to characterize the materials. The behavior of the
electrostrictive coupling constants in the limit of small drive amplitudes about
the bias voltage will be discussed. The effects of prestress, bias voltage, and
drive level on the coupling coefficient will be examined for each model. The
results will be compared with the equivalent piezoelectric definitions for k[inf
33].

ASA 132nd meeting - Hawaii, December 1996