Micromechanics analysis of space simulated thermal deformations and stresses in continuous fiber reinforced composites

dc.contributor.authorBowles, David Earlen
dc.contributor.committeechairGriffin, O. Hayden Jr.en
dc.contributor.committeememberHyer, Michael W.en
dc.contributor.committeememberReifsnider, Kenneth L.en
dc.contributor.committeememberSmith, Charles W.en
dc.contributor.committeememberTompkins, S.S.en
dc.contributor.departmentEngineering Mechanicsen
dc.description.abstractSpace simulated thermally induced deformations and stresses in continuous fiber-reinforced composites were investigated with a micromechanics analysis. The investigation focused on two primary areas. First, available explicit expressions for predicting the effective coefficients of thermal expansion (CTE's) for a composite were compared with each other and with a finite element (FE) analysis, developed specifically for this study. Analytical comparisons were made for a wide range of fiber/matrix systems, and predicted values were compared with experimental data. All of the analyses predicted nearly identical values of the axial CTE, α₁, for a given material system, and all of the predictions were in good agreement with the experimental data. Results from the FE analysis, and those from the solution of a generalized plane strain boundary value problem, were in excellent agreement with each other and with the experimental data for the transverse CTE, α₂. Less rigorous formulations were in poor agreement with the experimental data. The second area of investigation focused on the determination of thermally induced stress fields in the individual constituents. Stresses predicted from the FE analysis were compared to those predicted from a closed-from solution to the composite cylinder (CC) model, for two carbon fiber/epoxy composites. A global-local formulation, combining laminated plate theory and FE analysis, was used to determine the stresses in multidirectional laminates. Thermally-induced damage initiation predictions were also made. The type of analysis (i.e. CC or FE) was shown to significantly affect the distributions and magnitudes of the predicted stresses. Thermally-induced matrix stresses increased in absolute value with increasing fiber volume fraction but were not a strong function of fiber properties. Multidirectional [0₂/±θ]s laminates had larger predicted thermally induced matrix stresses than unidirectional ([0]) laminates, and these stresses increased with increasing lamination angle θ. Thermally-induced matrix failure predictions, using a maximum stress failure criterion based on the normal interfacial stress component and the measured transverse lamina strength, were in excellent agreement with experimental data.en
dc.description.degreePh. D.en
dc.format.extentx, 110 leavesen
dc.publisherVirginia Polytechnic Institute and State Universityen
dc.relation.isformatofOCLC# 21329492en
dc.rightsIn Copyrighten
dc.subject.lccLD5655.V856 1989.B684en
dc.subject.lcshGraphite fibersen
dc.subject.lcshFibrous compositesen
dc.titleMicromechanics analysis of space simulated thermal deformations and stresses in continuous fiber reinforced compositesen
thesis.degree.disciplineEngineering Mechanicsen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.namePh. D.en


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