<title>Shape memory alloy actuation for active tuning of composite beams</title>

Abstract

This paper presents an experimental-analytical study on the active tuning of composite beams using Shape Memory Alloy (SMA) wires. Composite beams with fused silica tubes and `dummy' wires were manufactured first using autoclave molding techniques and then the `dummy' wires were replaced by pre-strained SMA wires. The beam and SMA wire were independently clamped at both ends. The SMA wires were activated using electrical resistive heating and a large tensile recovery force developed in them due to the mechanical constraints provided by the clamps. The influence of this recovery force on the vibration behavior of composite beams was determined by conducting vibration testing. Analytically, these beams with SMA wires inserted in embedded sleeves were examined as beams on an elastic foundation: the spring constant of the elastic foundation depended on the axial recovery force of SMA wire. Good correlation between analysis and experiment was achieved. A numerical parametric study of natural frequencies of composite beams with activated SMA wires was conducted. The parameters considered were the diameter, number of SMA wires and constituent of composite beam. The numerical study suggests that inserting 25 SMA wires of 20 mil diameter into a graphite-epoxy beam of 30 in. length, 1 in. width and 62 mils thickness increases its first frequency by 276%.