Design, characterization, and assessment of the recurve actuation architecture.

Abstract

Piezoelectric actuation technology has proven useful for many applications because of its high energy density and fast response. Unfortunately, in many instances the useful work delivered to an application system is limited by the packaging of the actuator. To improve the performance that can be achieved in such applications, the work per package volume provided by the actuator must be increased through effective combination of four architectural features: package tailorability, performance tailorability, energy density, and packing density. The goal of this research was to design, characterize, and assess a new actuation architecture that utilizes these four features to improve the work per package volume that can be attained. The Recurve architecture, which was designed to meet this goal, provides energy dense strain amplification using a piezoelectrically activated composite beam building block. When a voltage is applied, the beam deflects without producing relative rotation at its ends. Using this feature, the building block elements can be rigidly connected into distributed array structures, with high packing density, without constraining one another. These array structures offer additional design variables that allow for simultaneous tailoring of the performance and packaging of the actuator. In this research, quasi-static and dynamic performance and limitation models were derived and validated through a series of designed experiments to predict the response of the Recurve architecture. These analytical models provide the basic tools that are necessary for application of this actuation architecture. Comparative metrics were also derived in this work for comparing the Recurve architecture to current strain amplifying piezoelectric actuators. Using these metrics, the Recurve architecture was shown to provide a significant improvement in work per package volume over a broad range. As a proof of concept, Recurve actuators were designed and fabricated for actuating a rotor blade flap, and physically demonstrated a significant improvement over existing approaches. Through the efforts of this research, the Recurve architecture stands as a viable actuation technology with the potential to elevate the performance of the current state of the art for package limited applications.