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Creep Deformation of Ceramics in Four‐Point Bending
Author(s) -
JAKUS KARL,
WIEDERHORN SHELDON M.
Publication year - 1988
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.1151-2916.1988.tb07531.x
Subject(s) - creep , materials science , composite material , flexural strength , ceramic , stress (linguistics) , compression (physics) , bending , tension (geology) , deformation (meteorology) , curvature , displacement (psychology) , geometry , mathematics , psychology , philosophy , linguistics , psychotherapist
Flexural testing was investigated as a method of studying the creep of ceramic materials at elevated temperatures. Three techniques were used to evaluate the steady‐state stress exponent: two of them were based on the measurement of the surface curvature of a flexure specimen after testing; the third was based on the more conventional technique of measuring displacement rate as a function of applied load and exposure time. Applied to a grade of commercial vitreous‐bonded alumina, the techniques yielded disparate results for the steady‐state stress exponent. This discrepancy in results is believed to be a consequence of the fact that ceramics tend to creep more readily in tension than in compression, leading to a shift in the neutral plane for stress and strain in flexural specimens, which results in extended primary creep. A local enhancement of creep under the loading points of the test specimens was observed in the materials tested; this creep enhancement was attributed to contact stresses at the loading points.