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X ray attenuation measurements for high-temperature materials characterization and in-situ monitoring of damage accumulationThe scope of this dissertation is to develop and apply x ray attenuation measurement systems that are capable of: (1) characterizing density variations in high-temperature materials, e.g., monolithic ceramics, ceramic and intermetallic matrix composites, and (2) noninvasively monitoring damage accumulation and failure sequences in ceramic matrix composites under room temperature tensile testing. This dissertation results in the development of: (1) a point scan digital radiography system, and (2) an in-situ x ray material testing system. Radiographic evaluation before, during, and after loading shows the effect of preexisting volume flaws on the fracture behavior of composites. Results show that x ray film radiography can monitor damage accumulation during tensile loading. Matrix cracking, fiber matrix debonding, fiber bridging, and fiber pullout are imaged throughout the tensile loading of the specimens. Further in-situ radiography is found to be a practical technique for estimating interfacial shear strength between the silicon carbide fibers and the reaction bonded silicon nitride matrix. It is concluded that pretest, in-situ, and post test x ray imaging can provide for greater understanding of ceramic matrix composite mechanical behavior.
Document ID
19920016753
Acquisition Source
Legacy CDMS
Document Type
Thesis/Dissertation
Authors
Baaklini, George Y.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
September 6, 2013
Publication Date
March 1, 1992
Subject Category
Composite Materials
Report/Patent Number
E-6652
NAS 1.15:105577
NASA-TM-105577
Accession Number
92N25996
Funding Number(s)
PROJECT: RTOP 510-01-50
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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