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dc.contributor.authorElseifi, Mohamed A.en_US
dc.date.accessioned2014-03-14T20:17:19Z
dc.date.available2014-03-14T20:17:19Z
dc.date.issued1998-11-09en_US
dc.identifier.otheretd-101198-161441en_US
dc.identifier.urihttp://hdl.handle.net/10919/29250
dc.description.abstractThin walled stiffened composite panels, which are among the most utilized structural elements in engineering, possess the unfortunate property of being highly sensitive to geometrical imperfections. Existing analysis codes are able to predict the nonlinear postbuckling behavior of a structure with specified imperfections. However, it is impossible to determine the geometric imperfection profile of a nonexistent composite panel early in the design. This is due to the variety of uncertainties that are involved in the manufacturing of these panels. As a mater of fact, due to the very nature of the manufacturing processes, it is hard to imagine that a given manufacturing process could ever produce two identical panels. The objective of this study is to introduce a new design methodology in which a manufacturing model and a convex model for uncertainties are used in conjunction with a nonlinear design tool in order to obtain a more realistic, better performing final design. First a finite element code for the nonlinear postbuckling analysis of stiffened panels is introduced. Next, a manufacturing model for the simulation of the autoclave curing of epoxy matrix composites is presented. A convex model for the uncertainties in the imperfections is developed in order to predict the weakest panel profile among a family of panels. Finally, the previously developed tools are linked in a closed loop design scheme aimed at obtaining a final design that incorporates the manufacturing tolerances information through more realistic imperfections.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartcover.pdfen_US
dc.relation.haspartch7.pdfen_US
dc.relation.haspartacknowledgements.pdfen_US
dc.relation.haspartabstract.pdfen_US
dc.relation.haspartch6.pdfen_US
dc.relation.haspartch5.pdfen_US
dc.relation.haspartch4.pdfen_US
dc.relation.haspartch3.pdfen_US
dc.relation.haspartch2.pdfen_US
dc.relation.haspartch1.pdfen_US
dc.relation.haspartappendix.pdfen_US
dc.relation.haspartlist_of_tables.pdfen_US
dc.relation.haspartlist_of_illustrations.pdfen_US
dc.relation.hasparttable_of_contents.pdfen_US
dc.relation.haspartreferences.pdfen_US
dc.relation.haspartvitae.pdfen_US
dc.rightsI hereby grant to Virginia Tech or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University Libraries in all forms of media, now or hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation.en_US
dc.subjectimperfectionsen_US
dc.subjectmanufacturingen_US
dc.subjectcomposite materialsen_US
dc.subjectpostbucklingen_US
dc.subjectconvex modelsen_US
dc.subjectdesign optimizationen_US
dc.subjectgenetic algorithmsen_US
dc.subjectnonlinear finite elementsen_US
dc.titleA new scheme for the optimum design of stiffened composite panels with geometric imperfectionsen_US
dc.typeDissertationen_US
dc.contributor.departmentAerospace and Ocean 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.disciplineAerospace and Ocean Engineeringen_US
dc.contributor.committeechairGürdal, Zaferen_US
dc.contributor.committeememberNikolaidis, Efstratiosen_US
dc.contributor.committeememberJohnson, Eric R.en_US
dc.contributor.committeememberJohnson, Eric R.en_US
dc.contributor.committeememberLoos, Alfred C.en_US
dc.contributor.committeememberHyer, Michael W.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-101198-161441/en_US
dc.date.sdate1998-10-12en_US
dc.date.rdate1998-11-13
dc.date.adate1998-11-13en_US


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