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R ‐Curve Behavior of Long Cracks in Alumina
Author(s) -
Steinbrech R.W.,
Reichl A.,
Schaarwächter W.
Publication year - 1990
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1990.tb05260.x
Subject(s) - materials science , crack growth resistance curve , composite material , microstructure , shielding effect , surface finish , bridging (networking) , fracture mechanics , ceramic , crack closure , electromagnetic shielding , computer network , computer science
Coarse‐grained alumina is among those monolithic ceramics which can exhibit an increase in crack resistance with crack extension. This R ‐curve behavior is most pronounced for intergranular fracture and does not depend exclusively on material properties. Crack and specimen geometries also influence the shape of the R ‐curves. The magnitude of the effect increases with increasing crack surface roughness, which is microstructure‐dependent, and with crack‐opening displacement, which is geometry‐dependent. Based on experimental observations, a “dynamic” R ‐curve model is presented which relates the increasing resistance to an increasing crack tip shielding caused by crack surface bridging. Applying a J ‐integral approach, R ‐curves are calculated for two specimen geometries (short double cantilever beam and single‐edged notched beam) and different grain sizes. The good agreement between calculation and experiment indicates that the R ‐curve behavior of long cracks in alumina can be predicted by a simple wake model.