Axisymmetric microfracture analysis of fiber-reinforced brittle composites.
Item
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Title
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Axisymmetric microfracture analysis of fiber-reinforced brittle composites.
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Identifier
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AAI9808028
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identifier
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9808028
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Creator
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Zhang, Hanqing.
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Contributor
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Adviser: Benjamin B. M. Liaw
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Date
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1997
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Mechanical | Engineering, Materials Science
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Abstract
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The mechanical behavior of ceramic-matrix composites (CMCs) depends mainly on the initiation and development of microdamage within the composites. In this study a three-cylinder model was developed to analyze the initiation of microdamage and its progression in CMCs. To verify the usefulness of this model, it was then used to simulate the damage progression in a ceramic matrix composite and to predict its tensile behavior. In the model, combination of the inner fiber and matrix cylinders represents a typical unit of the composite, while the outer composite medium models the rest of the material. The damage modes considered were multiple-matrix cracking, fiber-matrix interfacial debonding, and frictional interfacial sliding. The singular integral equation technique was used to formulate the problem. Effective numerical procedures were developed to solve the singular integral equations for accurate determination of the displacement and stress fields as well as the stress singularities. Complemented with the concepts of fracture mechanics and energy balance principle, the damage progression in a CMC, Nicalon/CAS II, under uniaxial tension was simulated. The predicted stress-strain curves are in good agreement with available experiment data. The effects of three important micromechanical parameters: the matrix fracture energy, the interfacial debonding energy and the interfacial friction stress on the damage progression within the composite and its macromechanical behavior were also thoroughly investigated. The model has been proven to be successful in capturing the damage mechanisms in CMCs and simulating their development with minimum reliance on experimental data.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
