### ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

## 4pEA15. Theoretical analysis of dynamic characteristics of piezoceramic
polymer composites with 2--2 connectivity.

**Q. M. Zhang
**

**
Xuecang Geng
**

**
**
*Intercollege Mater. Res. Lab., Penn State Univ., University Park, PA
16802
*

*
*
A dynamic model of piezoceramic polymer composites with 2--2 connectivity
is presented. It can be used to evaluate the dispersion curves for the
thickness resonance and the stop band edge resonance, the effective velocity of
the longitudinal wave, as well as the distributions of strain, stress, and the
electric field in a composite. Based on these results, the electromechanical
coupling factors are determined using two different methods according to the
IEEE recommendation. It is shown that the thickness mode coupling factor k[sub
t] obtained from the difference of the effective longitudinal velocities at the
constant electric field and constant electric displacement is in good agreement
with the experimental values. It is also shown that, due to the composite
structure, the piezoelectric shear coefficient e[sub 15] has a strong effect on
both the effective velocity of the longitudinal wave v[sup D] and k[sub t] even
at the limit where the composite thickness is much larger than the period. On
the other hand, k[sub t] calculated from the energy consideration is much
higher than the experimental values and cannot account correctly for the effect
of e[sub 15] on k[sub t]. From the model, the evolution of the thickness mode
and the stop band edge resonance with the thickness of a composite and the
modes coupling between the two can also be elucidated.