Effect of high-temperature and fiber distribution on matrix microcracking and toughness of ceramic matrix composites.
Item
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Title
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Effect of high-temperature and fiber distribution on matrix microcracking and toughness of ceramic matrix composites.
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Identifier
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AAI9130390
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identifier
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9130390
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Creator
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Xu, Yongli.
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Contributor
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Adviser: Feridun Delale
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Date
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1991
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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, Materials Science | Engineering, Mechanical
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Abstract
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The ceramic material has long been recognized as a material of potential uses owing to its very appealing features such as stability under high temperature and lightness. Nevertheless, due to low strength and fracture toughness, its structural use was limited. Through these years extensive efforts have been made to improve the toughness and strength of ceramic materials and ceramic composites are developed.;In this dissertation microcracking in ceramic matrix composites is studied. It is believed that behaviors of microscopic microcracks in the ceramic matrix composite have significant effect on the overall toughness and strength of the material. The aim of this study is to investigate effect of fiber distribution, and temperature on matrix microcracking and toughness of the material, because ceramic matrix composites are expected to work under high temperature circumstances.;In chapter II, III and IV, two theoretical models of microcracking (two-fiber model and ring model) are proposed and used for the analyses of microcracking. Stress intensity factors or strain energy release rates are calculated for radial, interfacial and matrix cracks for both mechanical and thermal loading. Effect of fiber distribution and mismatch of mechanical constants of fiber and matrix materials are investigated.;In chapter V, experimental results are reported. Effect of temperature on toughness of ceramic matrix materials (SiC and CAS II) is studied experimentally by using micro-indentation technique. Further, effect of fiber distribution as well as temperature on matrix microcracking are investigated. Experimental results are compared with theoretical predictions.;In chapter VI, fiber debonding tests are reported. Debonding test data are used for the calculation of bonding strength of fiber-matrix interfaces in conjunction with a theoretical model and finite element procedure. A formula for the evaluation of the bonding strength under elevated temperature using shear stress criterion is proposed.
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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.
