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dc.contributor.authorHarutyunyan, Sateniken_US
dc.date.accessioned2014-03-14T20:17:07Z
dc.date.available2014-03-14T20:17:07Z
dc.date.issued2008-09-11en_US
dc.identifier.otheretd-10062008-182837en_US
dc.identifier.urihttp://hdl.handle.net/10919/29209
dc.description.abstractIn addition to being useful for some nondestructive evaluation techniques, interactions between magnetic fields and defects in solids may also alter material properties. To explore this possibility, Maxwellâ s equations were coupled with a continuum mechanics model for elastic strain to formulate analytical expressions for the interaction of a magnetic field with several crack geometries. The influence of crack velocity and a realistic (nonlinear) magnetic susceptibility were included into a model of this type for the first time and shown to introduce unexpected trends in the magneto-elastic stress intensity. Singularities magneto-elastic stresses appear at different combinations of magnetic field strength and crack velocity, and the stresses at the crack tip switch sign. In a related study, the interaction of an alternating magnetic field with elastic stress through was explored through a coupling effect known as magneto-acoustic resonance. A model for the phenomena, in which magnetic waves excite elastic waves and vice versa, was formulated and used to explore the spin (magnon) and anti-plane elastic (phonon) interactions in piecewise homogeneous ferromagnetic spaces with two different sets of properties. The model suggests some combinations of magnetic field and frequency can produce a new kind of wave to appear. These new waves, which we call Accompanying Surface Magnetoelastic (ASM) waves, are localized at the interface between the two ferromagnetic media and they accompany reflection and transmission waves. It is shown that the amplitudes of the reflected, transmitted, and ASM waves depend strongly on magnetic field strength, frequency, and the angle of the incident wave, as well as on the physical properties of ferromagnetic media.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartDissertation_Harutyunyan_Final.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectRefractionen_US
dc.subjectReflectionen_US
dc.subjectWavesen_US
dc.subjectCracken_US
dc.subjectMagnetoelasticityen_US
dc.subjectFerromagneticen_US
dc.titleMagnetic and Elastic Interactions at Cracks and Interfaces in Ferromagnetic Materialsen_US
dc.typeDissertationen_US
dc.contributor.departmentMaterials Science and Engineeringen_US
dc.description.degreePh. D.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineMaterials Science and Engineeringen_US
dc.contributor.committeechairReynolds, William T. Jr.en_US
dc.contributor.committeememberWang, Yuen_US
dc.contributor.committeememberCorcoran, Sean Geralden_US
dc.contributor.committeememberAning, Alexander O.en_US
dc.contributor.committeememberHasanyan, Davreshen_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-10062008-182837/en_US
dc.date.sdate2008-10-06en_US
dc.date.rdate2008-10-20
dc.date.adate2008-10-20en_US


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