Optimization of composite box-beam structures including effects of subcomponent interaction

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dc.contributor.authorRagon, Scott Alanen
dc.contributor.committeechairGürdal, Zaferen
dc.contributor.committeememberGriffin, Odis Hayden Jr.en
dc.contributor.committeememberHaftka, Raphael T.en
dc.contributor.departmentEngineering Mechanicsen
dc.date.accessioned2014-03-14T21:38:38Zen
dc.date.adate2009-06-16en
dc.date.available2014-03-14T21:38:38Zen
dc.date.issued1994en
dc.date.rdate2009-06-16en
dc.date.sdate2009-06-16en
dc.description.abstractMinimum mass designs are obtained for a simple box beam structure subject to bending, torque and combined bending/torque load cases. These designs are obtained subject to point strain and linear buckling constraints. The present work differs from previous efforts in that special attention is payed to including the effects of subcomponent panel interaction in the optimal design process. Two different approaches are used to impose the buckling constraints. When the global approach is used, buckling constraints are imposed on the global structure via a linear eigenvalue analysis. This approach allows the subcomponent panels to interact in a realistic manner. The results obtained using this approach are compared to results obtained using a traditional, less expensive approach, called the local approach. When the local approach is used, in-plane loads are extracted from the global model and used to impose buckling constraints on each subcomponent panel individually. In the global cases, it is found that there can be significant interaction between skin, spar, and rib design variables. This coupling is weak or nonexistent in the local designs. It is determined that weight savings of up to 7% may be obtained by using the global approach instead of the local approach to design these structures. Several of the designs obtained using the linear buckling analysis are subjected to a geometrically nonlinear analysis. For the designs which were subjected to bending loads, the innermost rib panel begins to collapse at less than half the intended design load and in a mode different from that predicted by linear analysis. The discrepancy between the predicted linear and nonlinear responses is attributed to the effects of the nonlinear rib crushing load, and the parameter which controls this rib collapse failure mode is shown to be the rib thickness. The rib collapse failure mode may be avoided by increasing the rib thickness above the value obtained from the (linear analysis based) optimizer. It is concluded that it would be necessary to include geometric nonlinearities in the design optimization process if the true optimum in this case were to be found.en
dc.description.degreeMaster of Scienceen
dc.format.extentxv, 194 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-06162009-063327en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-06162009-063327/en
dc.identifier.urihttp://hdl.handle.net/10919/43336en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1994.R346.pdfen
dc.relation.isformatofOCLC# 31482373en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1994.R346en
dc.subject.lcshAirplanes -- Wings -- Design and constructionen
dc.subject.lcshBox beams -- Design and constructionen
dc.subject.lcshComposite constructionen
dc.titleOptimization of composite box-beam structures including effects of subcomponent interactionen
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineEngineering Mechanicsen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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