Failure Initiation and Progression in Internally Pressurized Non-Circular Composite Cylinders

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dc.contributor.authorWolford, Gabriela Fernandaen
dc.contributor.committeechairHyer, Michael W.en
dc.contributor.committeememberKraige, Luther Glennen
dc.contributor.committeememberCase, Scott W.en
dc.contributor.departmentEngineering Science and Mechanicsen
dc.date.accessioned2014-03-14T21:38:29Zen
dc.date.adate2003-07-03en
dc.date.available2014-03-14T21:38:29Zen
dc.date.issued2003-06-05en
dc.date.rdate2004-07-03en
dc.date.sdate2003-06-13en
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
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-06132003-105745en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-06132003-105745/en
dc.identifier.urihttp://hdl.handle.net/10919/43299en
dc.publisherVirginia Techen
dc.relation.haspartTHESIS.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectleakageen
dc.subjectelliptical cylindersen
dc.subjectmatrix crackingen
dc.subjectfiber failureen
dc.subjectnonlinear effectsen
dc.subjectprogressive failureen
dc.titleFailure Initiation and Progression in Internally Pressurized Non-Circular Composite Cylindersen
dc.typeThesisen
thesis.degree.disciplineEngineering Science and Mechanicsen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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