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dc.contributor.authorWolford, Gabriela Fernandaen_US
dc.date.accessioned2014-03-14T21:38:29Z
dc.date.available2014-03-14T21:38:29Z
dc.date.issued2003-06-05en_US
dc.identifier.otheretd-06132003-105745en_US
dc.identifier.urihttp://hdl.handle.net/10919/43299
dc.description.abstractIn this study, a progressive failure analysis is used to investigate leakage in internally pressurized non-circular composite cylinders. This type of approach accounts for the localized loss of stiffness when material failure occurs at some location in a structure by degrading the local material elastic properties by a certain factor. The manner in which this degradation of material properties takes place depends on the failure modes, which are determined by the application of a failure criterion. The finite-element code STAGS, which has the capability to perform progressive failure analysis using different degradation schemes and failure criteria, is utilized to analyze laboratory scale, graphite-epoxy, elliptical cylinders with quasi-isotropic, circumferentially-stiff, and axially-stiff material orthotropies. The results are divided into two parts. The first part shows that leakage, which is assumed to develop if there is material failure in every layer at some axial and circumferential location within the cylinder, does not occur without failure of fibers. Moreover before fibers begin to fail, only matrix tensile failures, or matrix cracking, takes place, and at least one layer in all three cylinders studied remain uncracked, preventing the formation of a leakage path. That determination is corroborated by the use of different degradation schemes and various failure criteria. Among the degradation schemes investigated are the degradation of different engineering properties, the use of various degradation factors, the recursive or non-recursive degradation of the engineering properties, and the degradation of material properties using different computational approaches. The failure criteria used in the analysis include the noninteractive maximum stress criterion and the interactive Hashin and Tsai-Wu criteria. The second part of the results shows that leakage occurs due to a combination of matrix tensile and compressive, fiber tensile and compressive, and inplane shear failure modes in all three cylinders. Leakage develops after a relatively low amount of fiber damage, at about the same pressure for three material orthotropies, and at approximately the same location.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartTHESIS.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.subjectleakageen_US
dc.subjectelliptical cylindersen_US
dc.subjectmatrix crackingen_US
dc.subjectfiber failureen_US
dc.subjectnonlinear effectsen_US
dc.subjectprogressive failureen_US
dc.titleFailure Initiation and Progression in Internally Pressurized Non-Circular Composite Cylindersen_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.committeechairHyer, Michael W.en_US
dc.contributor.committeememberKraige, Luther Glennen_US
dc.contributor.committeememberCase, Scott W.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-06132003-105745/en_US
dc.date.sdate2003-06-13en_US
dc.date.rdate2004-07-03
dc.date.adate2003-07-03en_US


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