Use of piezoelectric actuators as elements of intelligent structures

TLDR

The study develops and tests piezoelectric actuators for use in intelligent structures with distributed actuation, sensing, and processing. Analytic models for bonded or embedded segmented piezoelectric actuators were derived, scaled, and validated experimentally on aluminum, glass/epoxy, and graphite/epoxy cantilever beams to predict and excite resonant vibrations. The models accurately predicted beam responses, and experiments showed that embedded actuators reduced laminate ultimate strength by 20% without significantly affecting elastic modulus.

Abstract

This work presents the analytic and experimental development of piezoelectric actuators as elements of intelligent structures, i.e., structures with highly distributed actuators, sensors, and processing networks. Static and dynamic analytic models are derived for segmented piezoelectric actuators that are either bonded to an elastic substructure or embedded in a laminated composite. These models lead to the ability to predict, a priori, the response of the structural member to a command voltage applied to the piezoelectric and give guidance as to the optimal location for actuator placement. A scaling analysis is performed to demonstrate that the effectiveness of piezoelectric actuators is independent of the size of the structure and to evaluate various piezoelectric materials based on their effectiveness in transmitting strain to the substructure. Three test specimens of cantilevered beams were constructed: an aluminum beam with surface-bonded actuators, a glass/epoxy beam with embedded actuators, and a graphite/epoxy beam with embedded actuators. The actuators were used to excite steady-state resonant vibrations in the cantilevered beams. The response of the specimens compared well with those predicted by the analytic models. Static tensile tests performed on glass/epoxy laminates indicated that the embedded actuator reduced the ultimate strength of the laminate by 20%, while not significantly affecting the global elastic modulus of the specimen.