Transverse acoustic actuation of Ni-Mn-Ga single crystals

Two methods for the transverse acoustic actuation of {110}-cut Ni-Mn-Ga single crystals are discussed. In this actuation mode, crystals are used that have the {110}- type twinning planes parallel to the base of the crystal. The first method employs two 33-mode piezoelectric stacks, mounted at 45 deg to the base of a single crystal, to produce a shear stress on the 110 planes. The second method utilizes a single 15-mode piezoelectric stack, normally incident to the crystal base, to generate shear pulses directly. Both methods are capable of producing acoustic actuation. Due to the small size of the 15-mode stack, and the need to prestress the 33-mode stacks to prevent them from failing due to tensile stresses, the single stack actuator was chosen for further investigation. Engineering strains of up to -y = 0.12, the theoretical maximum for Ni-Mn-Ga, have been realized in the single stack configuration. Actuating over a smaller range, the actuator produced 5% strain in as little as 2.5 s, at a pulse frequency of 100 Hz, with over 3% occurring within the first second. Actuation against a load was also investigated. The blocking stress was found to be around 0.14 MPa, indicating that the acoustic stress exceeded the twinning stress by approximately this amount.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Simon, Jesse Matthew

Advisor dc:contributor.advisor

• Steven R. Hall.

• Aeronautics and Astronautics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/38653

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/38653