The influence of time-dependent material behavior on the response of sandwich beams

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dc.contributor.authorOleksuk, Lynda Lee Sensmeieren
dc.contributor.departmentEngineering Mechanicsen
dc.date.accessioned2014-03-14T21:31:09Zen
dc.date.adate2009-03-12en
dc.date.available2014-03-14T21:31:09Zen
dc.date.issued1990en
dc.date.rdate2009-03-12en
dc.date.sdate2009-03-12en
dc.description.abstractTo study the influence of the time-dependent behavior of various materials being considered for use in orbiting precision segmented reflectors, simple sandwich beam models are developed. The beam models included layers representing face sheets, core and adhesive. The issue of time-dependency is essential because the expected life of a reflector is on the order of 20 years. Using the principle of stationary potential energy, the elastic response of three-layer and five-layer symmetric sandwich beams to mechanical and thermally-induced loads is studied. The sensitivity of the three-layer and five-layer sandwich beams to reductions of the material properties is studied. Using the correspondence principle of viscoelasticity, these elastic models are transformed to time-dependent models. Representative cases of time-dependent material properties are used to demonstrate the application of the correspondence principle and evaluate the time-dependent response of the reflector. To verify the viscoelastic models, and to obtain a better idea of the amount of time-dependency to expect from the materials, simple time-dependent experiments on candidate materials were performed. Candidate materials include a quartz-epoxy face sheet material and a glass-imide honeycomb core material. The percent increase in strain for a constant stress for the quartz-epoxy in tension and the honeycomb in shear were measured. For both, a four-parameter fluid model captured the essential characteristics of their behavior. These four-parameter fluid models were then used in the three-layer sandwich beam model to predict the time-dependent response of the beam to three-point bending. This predicted response was compared to experimental results of a sandwich beam subjected to three-point bending.en
dc.description.degreeMaster of Scienceen
dc.format.extentx, 173 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-03122009-040737en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-03122009-040737/en
dc.identifier.urihttp://hdl.handle.net/10919/41474en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1990.O545.pdfen
dc.relation.isformatofOCLC# 23810444en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1990.O545en
dc.subject.lcshGirders -- Researchen
dc.titleThe influence of time-dependent material behavior on the response of sandwich beamsen
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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