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Viscoplastic Constitutive Theory Demonstrated for Monolithic Ceramic MaterialsDevelopment of accurate three-dimensional (multiaxial) inelastic stress-strain models is critical in utilizing advanced ceramics for challenging 21st century high-temperature structural applications. The current state of the art uses elastic stress fields as a basis for both subcritical crack growth and creep life prediction efforts aimed at predicting the time dependent reliability response of ceramic components subjected to elevated service temperatures. However, to successfully design components that will meet tomorrow's challenging requirements, design engineers must recognize that elastic predictions are inaccurate for these materials when subjected to high-temperature service conditions such as those encountered in advanced heat engine components. Analytical life prediction methodologies developed for advanced ceramics and other brittle materials must employ accurate constitutive models that capture the inelastic response exhibited by these materials at elevated service temperatures. A constitutive model recently developed at the NASA Lewis Research Center helps address this issue by accounting for the time-dependent (inelastic) material deformation phenomena (e.g., creep, rate sensitivity, and stress relaxation) exhibited by monolithic ceramics exposed to high-temperature service conditions. In addition, the proposed formulation is based on a threshold function that is sensitive to hydrostatic stress and allows different behavior in tension and compression, reflecting experimental observations obtained for these material systems.
Document ID
20050188539
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Janosik, Lesley A.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 23, 2013
Publication Date
April 1, 1999
Publication Information
Publication: Research and Technology 1998
Subject Category
Nonmetallic Materials
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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