Keywords

shape memory alloy, Ni-Ti-Fe, SMA, cryogenic, actuator

Abstract

Shape memory alloys (SMAs) possess the unique ability to change their shape by undergoing a solid-state phase transformation at a particular temperature. The shape change is associated with a large strain recovery as the material returns to its "remembered" shape. Their ability to act as both sensor and actuator has made them an attractive subject of study for numerous applications. SMAs have many characteristics which are advantageous in space-related applications, including generation of large forces associated with the strain recovery, smooth and controlled movements, large movement to weight ratio, high reliability, and spark-free operation. The objective of this work is the further development and testing of a cryogenic thermal conduction switch as part of NASA funded projects. The switch was developed to provide a variable conductive pathway between liquid methane and liquid oxygen dewars in order to passively regulate the methane temperature. Development of the switch concept has been continued in this work by utilizing Ni-Ti-Fe as the active SMA element. Ni-Ti-Fe exhibits the shape memory effect at cryogenic temperatures, which makes it well suited for low temperature applications. This alloy is also distinguished by an intermediate phase change known as the rhombohedral or R-phase, which is characterized by a small hysteresis (typically 1-2 deg C) and offers the advantage of precise control over a set temperature range. For the Ni-Ti-Fe alloy used, its thermomechanical processing, subsequent characterization using dilatometry and differential scanning calorimetry and implementation in the conduction switch configuration are addressed. This work was funded by grants from NASA KSC (NAG10-323) and NASA GRC (NAG3-2751).

Notes

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Graduation Date

2005

Semester

Spring

Advisor

Vaidyanathan, Rajan

Degree

Master of Science in Materials Science and Engineering (M.S.M.S.E.)

College

College of Engineering and Computer Science

Department

Mechanical, Materials and Aerospace Engineering

Degree Program

Materials Science and Engineering

Format

application/pdf

Identifier

CFE0000501

URL

http://purl.fcla.edu/fcla/etd/CFE0000501

Language

English

Release Date

January 2010

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

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