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dc.contributor.advisorLagoudas, Dimitris C.en_US
dc.creatorSchick, Justin Ryanen_US
dc.date.accessioned2011-02-22T22:24:24Zen_US
dc.date.accessioned2011-02-22T23:49:05Z
dc.date.available2011-02-22T22:24:24Zen_US
dc.date.available2011-02-22T23:49:05Z
dc.date.created2009-12en_US
dc.date.issued2011-02-22en_US
dc.date.submittedDecember 2009en_US
dc.identifier.urihttp://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7636en_US
dc.description.abstractIn this work the transformation induced fatigue of Ni-rich NiTi shape memory alloys (SMAs) was investigated. The aerospace industry is currently considering implementing SMA actuators into new applications. However, before any new applications can be put into production they must first be certified by the FAA. Part of this certification process includes the actuator fatigue life. In this study, as-received and polished at dogbone SMA specimens underwent transformation induced fatigue testing at constant loading. The constant applied loading ranged from 100 MPa to 200 MPa. Specimens were thermally cycled through complete actuation (above Af to below Mf ) by Joule heating and environmental cooling. There were three cooling environments studied: liquid, gaseous nitrogen and vortex cooled air. It was shown that polished specimens had fatigue lives that were two to four times longer than those of as-received specimens. Test environment was also found to have an effect on fatigue life. Liquid cooling was observed to be corrosive, while the gaseous nitrogen and vortex air cooling were observed to be non-corrosive. The two non-corrosive cooling environments performed similarly with specimen fatigue lives that were twice that of specimens fatigue tested in the corrosive cooling environment. Transformation induced fatigue testing of polished specimens in a non-corrosive environment at 200 MPa had an average fatigue life of 14400 actuation cycles; at 150 MPa the average fatigue life was 20800 cycles and at 100 MPa it was 111000 cycles. For all specimens constant actuation from the beginning of testing until failure was observed, without the need for training. Finally, a microstructural study showed that the Ni3Ti precipitates in the material were one of the causes of crack initiation and propagation in the actuators.en_US
dc.format.mimetypeapplication/pdfen_US
dc.language.isoen_USen_US
dc.subjectShape Memory Alloysen_US
dc.subjectTransformation Induced Fatigueen_US
dc.subjectVortex Coolingen_US
dc.subjectThermal Actuationen_US
dc.titleTransformation Induced Fatigue of Ni-Rich NiTi Shape Memory Alloy Actuatorsen_US
dc.typeBooken
dc.typeThesisen
thesis.degree.departmentAerospace Engineeringen_US
thesis.degree.disciplineAerospace Engineeringen_US
thesis.degree.grantorTexas A&M Universityen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelMastersen_US
dc.contributor.committeeMemberBenzerga, Amineen_US
dc.contributor.committeeMemberKaraman, Ibrahimen_US
dc.type.genreElectronic Thesisen_US
dc.type.materialtexten_US


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