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Creep‐Crack Growth by Damage Accumulation in a Glass‐Ceramic
Author(s) -
Chan Kwai S.,
Page Richard A.
Publication year - 1991
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.1151-2916.1991.tb07146.x
Subject(s) - creep , materials science , composite material , coalescence (physics) , crack closure , nucleation , ceramic , scanning electron microscope , fracture mechanics , ultimate tensile strength , crack growth resistance curve , chemistry , physics , organic chemistry , astrobiology
The growth rate, near‐tip creep response, and damage processes of creep cracks in a pyroceram glass‐ceramic were studied under tensile loading at elevated temperatures. The rates of crack extension were characterized as a function of the applied stress intensity factor. The damage processes which occurred near the crack tip and led to creep crack extension were identified using a replica technique and by direct observations in a scanning electron microscope equipped with a high‐temperature loading stage. The accumulated creep strains near the crack tip were measured via the stereoimaging technique. The results indicate that creep‐crack growth in the pyroceram glass‐ceramic occurs in both continuous and discontinuous manners, with the damage processes manifested as the nucleation, growth, and coalescence of inhomogeneously distributed cavities and microcracks. Measurements of the total accumulated creep strain near the crack tip suggest that crack extension follows a critical strain criterion. Both the microcrack density and the total accumulated creep strain show similar dependence with distance from the crack tip. These observations suggest that damage accumulation and crack extension in the glass‐ceramic are controlled by the near‐tip creep rates.