Use of Material Tailoring to Improve Axial Load Capacity of Elliptical Composite Cylinders

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dc.contributor.authorSun, Miaoen
dc.contributor.committeechairHyer, Michael W.en
dc.contributor.committeememberPatil, Mayuresh J.en
dc.contributor.committeememberCase, Scott W.en
dc.contributor.committeememberCramer, Mark S.en
dc.contributor.committeememberLibrescu, Liviuen
dc.contributor.departmentEngineering Science and Mechanicsen
dc.date.accessioned2014-03-14T20:18:50Zen
dc.date.adate2006-12-01en
dc.date.available2014-03-14T20:18:50Zen
dc.date.issued2006-11-16en
dc.date.rdate2006-12-01en
dc.date.sdate2006-11-20en
dc.description.abstractThis study focuses on the improvement of the axial buckling capacity of elliptical composite cylinders through the use of a circumferentially-varying lamination sequence. The concept of varying the lamination sequence around the circumference is considered as a viable approach for off-setting the disadvantages of having the cylinder radius of curvature vary with circumferential position, the source of the reduced buckling capacity when compared to a circular cylinder with the same circumference. Post-buckling collapse behavior and material failure characteristics are also of interest. Two approaches to implementing a circumferential variation of lamination are examined. For the first approach the lamination sequence is varied in a stepwise fashion around the circumference. Specifically, each quadrant of the cylinder circumference is divided into three equal-length regions denoted as the crown, middle, and side regions. Eight different cylinders designs, whereby each region is constructed of either a quasi-isotropic or an axially-stiff laminate of equal thickness, are studied. Results are compared to the baseline case of an elliptical cylinder constructed entirely of a quasi-isotropic laminate. Since the thickness of the quasi-isotropic and axially-stiff laminates are the same, all cylinders weight the same and thus comparisons are meaningful. Improvements upwards of 18% in axial buckling capacity can be achieved with one particular stepwise design. The second approach considers laminations that vary circumferentially in a continuous fashion to mitigate the effects of the continuously-varying radius of curvature. The methodology for determining how to tailor the lamination sequence circumferentially is based on the analytical predictions of a simple buckling analysis for simply-supported circular cylinders. With this approach, axial buckling load improvements upwards of 30% are realized. Of all the cylinders considered, very few do not exhibit material failure upon collapse in the post-buckled state. Of those that do not, there is little, if any, improvement in bucking capacity. Results for the pre-buckling, buckling, post-buckling, and material failure are obtained from the finite-element code ABAQUS using both static and dynamic analyses. Studies with the code demonstrate that the results obtained are converged.en
dc.description.degreePh. D.en
dc.identifier.otheretd-11202006-124553en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-11202006-124553/en
dc.identifier.urihttp://hdl.handle.net/10919/29693en
dc.publisherVirginia Techen
dc.relation.haspartsubmit-11-29.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectBucklingen
dc.subjectMaterial Tailoringen
dc.subjectElliptical Cylinderen
dc.subjectCompositeen
dc.subjectMaterial Failureen
dc.subjectStabilityen
dc.subjectPost-bucklingen
dc.titleUse of Material Tailoring to Improve Axial Load Capacity of Elliptical Composite Cylindersen
dc.typeDissertationen
thesis.degree.disciplineEngineering Science and Mechanicsen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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