Influence of layer waviness on the hydrostatic response of thick composite cylinders

dc.contributor.authorBrown, Timothy L.en
dc.contributor.committeechairHyer, Michael W.en
dc.contributor.committeememberGriffin, Odis Hayden Jr.en
dc.contributor.committeememberMorris, Don H.en
dc.contributor.departmentEngineering Mechanicsen
dc.date.accessioned2014-03-14T21:46:07Zen
dc.date.adate2009-09-19en
dc.date.available2014-03-14T21:46:07Zen
dc.date.issued1992-06-06en
dc.date.rdate2009-09-19en
dc.date.sdate2009-09-19en
dc.description.abstractThe influence of layer waviness in thick cross-ply composite cylinders subjected to hydrostatic pressure is investigated. The cylinders considered are graphite-epoxy with a 2: 1 ratio of circumferential to axial layers. All cylinders considered contain 104 total layers with a layup of [90/(90/0/90h71s, where a '0° 1 layer is taken to be in the axial direction. The influence of a single isolated group of wavy layers in an otherwise perfect cylinder is evaluated. Layer waviness in only the circumferential direction is considered, and the analysis is assumed to be valid only away from the cylinder ends. A parametric investigation is performed to determine the combined influence of wave location, wave amplitude, and cylinder geometry on hydrostatic response of the cylinder, particularly the stresses generated in and around the wave. The wave is assumed to be located either at the inner or the outer radius of the cylinder. Three wave amplitudes, 0, are considered: 1/2, 1, and 2 layer thicknesses. Only waves with a half wave length of 10 layer thicknesses are considered. Three cylinder geometries are considered, specifically ones with radius to thickness ratios of 5, 10, and 20. Finite element analysis is used to determine the stress state within the imperfect, i.e., wave included, cylinders. Based on a maximum stress failure criterion, failure pressures are determined for each of the various wave and cylinder geometries. Failure pressures for the imperfect cylinders are compared with those for a perfect cylinder to determine the failure pressure reduction ratios due to fiber waviness. It is shown that pressure capacity reductions of approximately 50% are possible for the range of parameters studied. Failure is primarily due to fiber compression, though interlaminar shear and interlaminar tension are a factor. Finite element analysis is also used to deter ine the failure pressure of the perfect cylinder due to buckling. This is done to determine whether failure due to buckling may overshadow material failure due to fiber waviness. It is shown that buckling is a factor in only one of the cylinder geometries considered, and only in the cases of mild layer waviness. In addition to results, details about the finite element model are presented. These details include geometry of the wave, changes in material properties due to local fiber rotation and local volume fraction changes, boundary conditions, and justifications for modeling simplifications that were made in an effort to reduce computational costs and analysis times.en
dc.description.degreeMaster of Scienceen
dc.format.extentxiii, 233 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-09192009-040247en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-09192009-040247/en
dc.identifier.urihttp://hdl.handle.net/10919/44845en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1992.B769.pdfen
dc.relation.isformatofOCLC# 26487416en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1992.B769en
dc.subject.lcshComposite materialsen
dc.subject.lcshCylinders -- Hydrodynamicsen
dc.subject.lcshHydrostatic pressureen
dc.titleInfluence of layer waviness on the hydrostatic response of thick composite cylindersen
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
Files
Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
LD5655.V855_1992.B769.pdf
Size:
7.51 MB
Format:
Adobe Portable Document Format
Collections