Finite Element Analysis of the Deformation of a Rubber Diaphragm

dc.contributor.authorIonita, Axinteen
dc.contributor.committeechairGao, David Y.en
dc.contributor.committeememberLibrescu, Liviuen
dc.contributor.committeememberReifsnider, Kenneth L.en
dc.contributor.committeememberHenneke, Edmund G. IIen
dc.contributor.committeememberRagab, Saad A.en
dc.contributor.departmentEngineering Science and Mechanicsen
dc.date.accessioned2014-03-14T20:07:44Zen
dc.date.adate2001-03-06en
dc.date.available2014-03-14T20:07:44Zen
dc.date.issued2001-02-05en
dc.date.rdate2002-03-06en
dc.date.sdate2001-02-23en
dc.description.abstractSeveral rubber diaphragms, of the same type used inside an hydraulic accumulator, failed a short time after they were mounted. While there is nothing special with these failures the cost, in some cases can be high. A closer look, at the damaged diaphragms reveal an interesting nonsymmetric radial deformation accompanied in some cases by cracks. Most of the analyses regarding the failures of rubber diaphragms offer explanations only from a chemical or material science point of view. We propose in this thesis a new perspective from a mechanical-structural engineering view. Therefore the main goal of the thesis is to investigate the deformation of a diaphragm and based on this analysis to propose an explanation for formation of the cracks. It is shown that the analysis of the diaphragm problem leads to a pseudo-nonconservative system and involves a buckling, a post buckling (dynamic snap-through), an eversion, and a load response analysis. The problem is approached numerically using the nite element method. The character of pseudo-nonconservativeness of the system requires, in this case, an update of the tangent stiffness matrix with a certain stiffness correction. This new correction is proposed also. The result is valid not only for this particular problem but for the entire class of problems to which the diaphragm belongs. This correction is implemented in an existing nite element program (NIKE3D) and used to analyze the diaphragm deformation. The results indicate that under the typical load condition for a diaphragm a certain deformation pattern occurs, and this can lead to the formation of cracks. This deformation matches extremely well with the actual deformed shape of a typical failed diaphragm. It is shown that the deformation pattern depends on the structural properties of the diaphragm rather than on the magnitude of the applied load. The nonsymmetry in the diaphragm deformation and the difference in the crack development is explained also.en
dc.description.degreePh. D.en
dc.identifier.otheretd-02232001-114006en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-02232001-114006/en
dc.identifier.urihttp://hdl.handle.net/10919/26286en
dc.publisherVirginia Techen
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dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectFinite element methoden
dc.subjectDiaphragmen
dc.subjectRubberen
dc.subjectEversionen
dc.subjectBucklingen
dc.titleFinite Element Analysis of the Deformation of a Rubber Diaphragmen
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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