Date of Award

3-10-2010

Document Type

Thesis

Degree Name

Master of Science in Aeronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Jonathan T. Black, PhD

Abstract

This research sought to validate a proof of concept regarding shape memory alloy actuation of a flapping-wing blimp. Specimen wires were subjected to cyclic voltage at increasing frequencies to quantify expected strains. A laser vibrometer captured 2048 sample velocities during single contraction and elongation cycles, and the resulting samples were used to calculate displacements. Displacements were determined ten times for each specimen and frequency to compute averages. Subsequently, a circumventing frame was designed to encase a blimp envelope and provide support for a flapping motion actuation system. Contraction of shape memory wire translated force to the flapping mechanism via bellcranks, pushrods, and clevises, while bias springs promoted elongation of the wire during power-off phases. Performance characteristics of the flapping system, augmented with each specimen wire individually, were determined during bench-top testing. A modified frame design was constructed when it was determined that the weight of the prototype exceeded the buoyant force of the blimp envelope. The modified frame was later fitted to a larger blimp envelope, because it too exceeded the weight restriction of the original envelope. Subsequently, a circuit was constructed to cycle voltage at 0.2 hertz as applied to the actuating specimen wires, and performance of the system observed with the incorporation of each specimen. The modified prototype showed optimum performance of 25 to 35 degrees wing deflection while incorporating a 0.005 inch diameter shape memory wire.

AFIT Designator

AFIT-GAE-ENY-10-M02

DTIC Accession Number

ADA518017

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