Show simple item record

dc.contributor.authorShah, Priyalen_US
dc.date.accessioned2017-04-06T08:00:16Z
dc.date.available2017-04-06T08:00:16Z
dc.date.issued2017-04-05en_US
dc.identifier.othervt_gsexam:9751en_US
dc.identifier.urihttp://hdl.handle.net/10919/77034
dc.description.abstractWe numerically analyze three mechanics problems described below. For each problem, the developed computational model is verified by comparing computed results for example problems with those available in the literature. Effective utilization of single wall carbon nanotubes (SWCNTs) and single layer graphene sheets (SLGSs) as reinforcements in nanocomposites requires their strong binding with the surrounding matrix. An effective technique to enhance this binding is to functionalize SWCNTs and SLGSs by covalent attachment of appropriate chemical groups. However, this damages their pristine structures that may degrade their mechanical properties. Here, we delineate using molecular mechanics simulations effects of covalent functionalization on elastic moduli of these nanomaterials. It is found that Young's modulus and the shear modulus of an SWCNT (SLGS), respectively, decrease by about 34% (73%) and 43% (42%) when 20% (10%) of carbon atoms are functionalized for each of the four functional groups of different polarities studied. A shell theory that gives results close to the solution of the corresponding 3-dimensional problem depends upon the shell geometry, applied loads, and initial and boundary conditions. Here, by using a third order shear and normal deformable theory and the finite element method (FEM), we delineate for a doubly curved shell deformed statically with general tractions and subjected to different boundary conditions effects of geometric parameters on in-plane and transverse stretching and bending deformations. These results should help designers decide when to consider effects of these deformation modes for doubly curved shells. Composite laminates are usually fabricated by curing resin pre-impregnated fiber layers in an autoclave under prescribed temperature and pressure cycles. A challenge is to reduce residual stresses developed during this process and simultaneously minimize the cure cycle time. Here, we use the FEM and a genetic algorithm to find the optimal cycle parameters. It is found that in comparison to the manufacturer's recommended cycle, for a laminate with the span/thickness of 12.5, one optimal cycle reduces residual stresses by 47% and the total cure time from 5 to 4 hours, and another reduces the total cure time to 2 hours and residual stresses by 8%.en_US
dc.format.mediumETDen_US
dc.publisherVirginia Techen_US
dc.rightsThis item is protected by copyright and/or related rights. Some uses of this item may be deemed fair and permitted by law even without permission from the rights holder(s), or the rights holder(s) may have licensed the work for use under certain conditions. For other uses you need to obtain permission from the rights holder(s).en_US
dc.subjectCarbon nanotubeen_US
dc.subjectGrapheneen_US
dc.subjectMolecular mechanicsen_US
dc.subjectComposite laminatesen_US
dc.subjectDoubly curved shellsen_US
dc.subjectSandwich shellsen_US
dc.subjectTSNDTen_US
dc.subjectStress recovery schemeen_US
dc.subjectCure process modelingen_US
dc.subjectCure cycle optimizationen_US
dc.subjectGenetic Algorithmen_US
dc.titleComputational Analysis of Elastic Moduli of Covalently Functionalized Carbon Nanomaterials, Infinitesimal Elastostatic Deformations of Doubly Curved Laminated Shells, and Curing of Laminatesen_US
dc.typeDissertationen_US
dc.contributor.departmentEngineering Science and Mechanicsen_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.disciplineEngineering Mechanicsen_US
dc.contributor.committeechairBatra, Romesh C.en_US
dc.contributor.committeememberFloyd, William J.en_US
dc.contributor.committeememberHendricks, Scott L.en_US
dc.contributor.committeememberSeidel, Gary D.en_US
dc.contributor.committeememberCramer, Mark S.en_US


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record