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dc.contributor.authorYoo, Byungseoken_US
dc.date.accessioned2014-03-14T20:50:30Z
dc.date.available2014-03-14T20:50:30Z
dc.date.issued2006-12-12en_US
dc.identifier.otheretd-12202006-112642en_US
dc.identifier.urihttp://hdl.handle.net/10919/36335
dc.description.abstractThe ultrasonic NDE technique to characterize the ultrasonic nonlinear response of the cyclically load 7075-T6 aluminum is described in this thesis. In order to estimate the nonlinear relation of the ultrasonic waves due to material fatigue damage or degradation, the spectral analysis techniques such as the power spectrum, bispectrum, and bicoherence spectrum are applied. The ultrasonic nonlinearity parameters by Cantrell and Jhang are introduced and presented as a function of the material fatigue growth, the number of fatigue cycles. This thesis presents the effectiveness of the bispectral analysis for evaluating the nonlinear aspects of the ultrasonic wave propagation. The results show that the nonlinearity parameters by Cantrell and Jhang are responsive to the output amplitude of the received signal and vary for the various materials, and independent of the input frequency and the ultrasonic wave propagation distance. By using the bispectral analysis tools, particularly the bicoherence spectrum, the increase of the coupling levels between the fundamental, its harmonic, and subharmonic frequency components is presented as the number of fatigue cycles is increased. This thesis suggests that the application of the bicoherence spectrum based on the nonlinear wave coupling relations be more effective for estimating the level of the material fatigue life.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartByungseok_Yoo_MS_Thesis.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.subjectUltrasonicen_US
dc.subjectNDEen_US
dc.subjectNonlinearity Parameteren_US
dc.subjectPower Spectrumen_US
dc.subjectBispectrumen_US
dc.subjectBicoherence Spectrumen_US
dc.titlePractical Aspects of Assessing Nonlinear Ultrasonic Response of Cyclically Load 7075-T6 Aluminumen_US
dc.typeThesisen_US
dc.contributor.departmentEngineering Science and Mechanicsen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineEngineering Science and Mechanicsen_US
dc.contributor.committeechairDuke, John C. Jr.en_US
dc.contributor.committeememberKriz, Ronald D.en_US
dc.contributor.committeememberHajj, Muhammad R.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-12202006-112642/en_US
dc.date.sdate2006-12-20en_US
dc.date.rdate2007-01-09
dc.date.adate2007-01-09en_US


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