Tuesday, 12 October 2004 - 10:30 AM

This presentation is part of : Active Materials

Dynamic Response of Piezoelectric Polymers

Aleksandra Vinogradov, Montana State University, Montana State University, 220 Roberts Hall, Bozeman, MT 59717

In the past decades, rapid advances in polymer science have led to an explosive growth in the development and use of piezoelectric polymers. Currently, the principal commercially available group of piezoelectric polymers includes polyvinylidene fluoride (PVDF) and PVDF co-polymers. To date, considerable research efforts have been directed towards characterizing the electromechanical properties of these materials. It has been established, in particular, that the response of piezoelectric polymers is time and temperature dependent. In view of the fact that piezoelectric polymers usually perform in dynamic environments, accurate characterization of their response under vibratory loading conditions is of particular practical significance. An investigation of the dynamic properties of PVDF over a range of temperatures and frequencies is the focus area of the present paper.

The study reported in this paper is based on a consistent experimental program developed to determine the response of PVDF under superimposed static and cyclic loads. The results demonstrate that the cyclic response of PVDF is characterized by much higher creep rates than those observed from standard laboratory creep experiments. The acceleration of creep rates in piezoelectric polymers subjected to cyclic loads is essentially a nonlinear phenomenon defined as "vibrocreep." Experimental results demonstrate that vibrocreep rates of PVDF depend on the mean stress, cyclic frequency and amplitude. It is clear that the interactive mechanisms involving creep and cyclic loading effects tend to dominate the long-term functional performance and durability of piezoelectric polymers. In the paper, practical implications of these results are discussed.

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