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Proceedings Paper

Experimental characterization of Ni-Ti shape memory alloy wires under complex loading conditions
Author(s): Harsha Prahlad; Inderjit Chopra
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Paper Abstract

Shape memory alloys (SMAs) have shown promise as high-force, high displacement actuators. Critical issues such as path- dependence, predictability and sensitivity to testing conditions, however, need to be addressed in order to design controllable actuators using SMAs. This paper presents research aimed at addressing some of design issues involving application of SMAs, particularly at actuators. Quasistatic experiments at constant stress, strain and temperature are consolidated on a critical stress-temperature diagram to delineate the regions of stability of the various phases of the material. The critical points from these quasistatic tests are found to be in excellent agreement with each other, and correlate relatively well with the constitutive models for SMA thermomechanical behavior. It is also observed that the state of the material is not unique at points along the transformation, and is dependent on the history of the material before the start of the test, individual test involved, the method of loading, and loading rates. Significant variation of the state of the material with different rates and conditions of loading are shown to further illustrate this point. This behavior is likely to be decisive in determining the dynamic behavior of the material, and underscores the need for approaches incorporating these issues for design of repeatable actuators.

Paper Details

Date Published: 9 June 1999
PDF: 13 pages
Proc. SPIE 3668, Smart Structures and Materials 1999: Smart Structures and Integrated Systems, (9 June 1999); doi: 10.1117/12.350736
Show Author Affiliations
Harsha Prahlad, Univ. of Maryland/College Park (United States)
Inderjit Chopra, Univ. of Maryland/College Park (United States)

Published in SPIE Proceedings Vol. 3668:
Smart Structures and Materials 1999: Smart Structures and Integrated Systems
Norman M. Wereley, Editor(s)

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