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Proceedings Paper

Simple thermal actuator using R-phase transformation of Nitinol
Author(s): Jayagopal Uchil; Kumara K. Ganesh; K.K. Mahesh
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Paper Abstract

R<-->A phase transformation in NiTi alloy is associated with a very small recoverable strain of the order of 0.5% compared to that of 6-8% recoverable strain of M<-->A transformation. The stability of R<-->A transformation against large number of thermal cycles is an attractive feature for an application of SMA. A spring of NiTi is designed and fabricated, using 40% prior cold worked nitinol wire of dia 1mm, with appropriate heat-treatment such that martensitic transformation takes place through two stage A-->R-->M. The transformation behaviors of this wire are studied using DSC and electrical resistivity measurements. Further, the spring has been subjected to thermo-mechanical treatment for getting a two-way memory, viz:, while heating the spring gets contracted and while cooling it gets elongated. This spring has been used as an thermal actuator and temperature variation is confined between 50-65 degree(s)C to utilize only R<-->A transformation. Linear stroke of 4cm by the spring is used to rotate a platform carrying a load of 2 kg. The efficiency and reliability of the spring is tested over a million thermal cycles.

Paper Details

Date Published: 15 July 2002
PDF: 8 pages
Proc. SPIE 4701, Smart Structures and Materials 2002: Smart Structures and Integrated Systems, (15 July 2002); doi: 10.1117/12.474680
Show Author Affiliations
Jayagopal Uchil, Mangalore Univ. (India)
Kumara K. Ganesh, Mangalore Univ. (India)
K.K. Mahesh, Mangalore Univ. (India)

Published in SPIE Proceedings Vol. 4701:
Smart Structures and Materials 2002: Smart Structures and Integrated Systems
L. Porter Davis, Editor(s)

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