Date of Award

3-9-2009

Document Type

Thesis

Degree Name

Master of Science in Electrical Engineering

Department

Department of Electrical and Computer Engineering

First Advisor

LaVern A. Starman, PhD

Abstract

This research effort presents conceptual micro scale air vehicles whose total dimensions are less than one millimeter. The initial effort was to advance the understanding of micro aerial vehicles at sub-millimeter dimensions by fabricating and testing micro scale flapping wings. Fabrication was accomplished using a surface micromachining process called PolyMUMPs™. Both rigid mechanical structures and biomimetic devices were designed and fabricated as part of this effort. The rigid mechanical structures focused on out of plane deflections with solid connections and assembling a multiple hinge wing structure through the aid of residual stress. These devices were actuated by double hot arm thermal actuators. The biomimetic structures derived from three different insect wings to include; the dragonfly, house fly, and butterfly were selected based off of an attribute that each insect possesses in nature. The dragonfly was chosen for its high maneuverability and hovering capabilities. The house fly wing was chosen because of its durability and the butterfly wing was chosen because of its flexibility. The fabricated wings utilize a thermal bimorph structure consisting of polysilicon and gold which allows device actuation through joule heating. The released micro wings had an initial upward deflection due to residual stress between the gold and polysilicon material layers. Joule heating, from an applied bias, forces the wing to deflect downward due to the coefficient of thermal expansion mismatch between the material layers. Each fabricated bio-wing structure was tested for deflection range as well as operating frequency. From the experimental testing of the micro scale flapping bio-wings, aerodynamic values were calculated to include; aspect ratio, reduced frequency in a hover, Reynolds number of a hovering device, drag force, and gravitational force. The research verified insect based wings on the micro scale are capable of producing the desired flapping motion.

AFIT Designator

AFIT-GE-ENG-09-09

DTIC Accession Number

ADA497687

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