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Slow crack growth in ceramic polycrystals: A local description to estimate the effect of the failure kinetics and role of the microstructure

Slow crack growth in ceramic polycrystals: A local description to estimate the effect of the... Intergranular slow crack growth (SCG) in ceramic polycrystal is described with a cohesive zone model that mechanically simulates the reaction-rupture mechanism underlying stress and environmentally assisted failure. A 2D polycrystal is considered with cohesive surfaces inserted along the grain boundaries. The anisotropic elastic modulus and grain-to-grain misorientation are accounted for together with an initial stress state related to the processing. A minimum load threshold is shown to originate from the onset of the reaction-rupture mechanism to proceed where a minimum traction is reached locally and from the magnitude of the initial compression stresses. The cohesive model incorporates a characteristic length scale, so that size effects can be investigated. SCG is grain size dependent with the decrease of the crack velocity at a given load level and improvement of the load threshold with the grain size. Polycrystals of zirconia and alumina are both considered in the current study and a comparison between SCG resistance of alumina and zirconia is presented. This work aims at providing reliable predictions in long lasting applications of ceramics. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Strength, Fracture and Complexity iospress

Slow crack growth in ceramic polycrystals: A local description to estimate the effect of the failure kinetics and role of the microstructure

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Publisher
IOS Press
Copyright
Copyright © 2019 IOS Press and the authors. All rights reserved
ISSN
1567-2069
eISSN
1875-9262
DOI
10.3233/SFC-180231
Publisher site
See Article on Publisher Site

Abstract

Intergranular slow crack growth (SCG) in ceramic polycrystal is described with a cohesive zone model that mechanically simulates the reaction-rupture mechanism underlying stress and environmentally assisted failure. A 2D polycrystal is considered with cohesive surfaces inserted along the grain boundaries. The anisotropic elastic modulus and grain-to-grain misorientation are accounted for together with an initial stress state related to the processing. A minimum load threshold is shown to originate from the onset of the reaction-rupture mechanism to proceed where a minimum traction is reached locally and from the magnitude of the initial compression stresses. The cohesive model incorporates a characteristic length scale, so that size effects can be investigated. SCG is grain size dependent with the decrease of the crack velocity at a given load level and improvement of the load threshold with the grain size. Polycrystals of zirconia and alumina are both considered in the current study and a comparison between SCG resistance of alumina and zirconia is presented. This work aims at providing reliable predictions in long lasting applications of ceramics.

Journal

Strength, Fracture and Complexityiospress

Published: Jan 1, 2019

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