Characteristics of the double-torsion test to determine the R-curve of ceramic materials

Double-torsion tests were carried out on a commercial ceramic floor tile to verify whether this test is suitable for determining the R-curve of ceramics. The instantaneous crack length was obtained by compliance calibration, and it was found that the experimental compliance underestimated the real c...

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Bibliographic Details
Published in:Materials research (São Carlos, São Paulo, Brazil) São Paulo, Brazil), 2006-12, Vol.9 (4), p.361-368
Main Authors: Albuquerque, Maria da Consolação Fonseca de, Rodrigues, José de Anchieta
Format: Article
Language:English
Subjects:
double-torsion
ENGINEERING, CHEMICAL
fracture mechanics
MATERIALS SCIENCE, MULTIDISCIPLINARY
METALLURGY & METALLURGICAL ENGINEERING
R-curve
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Summary:Double-torsion tests were carried out on a commercial ceramic floor tile to verify whether this test is suitable for determining the R-curve of ceramics. The instantaneous crack length was obtained by compliance calibration, and it was found that the experimental compliance underestimated the real crack length. The load vs. displacement curves also dropped after maximum loading, causing the stress intensity factor to decline. The R-curves were calculated by two methods: linear elastic fracture mechanics and the energetic method. The average values of crack resistance, R, and the double of the work of fracture, 2.gamma(wof), did not depend on the notch length, which is a highly relevant finding, indicating that these parameters were less dependent on the test specimen's geometry. The proposal was to use small notches, which produce long stable crack propagation paths that in turn are particularly important in the case of coarse microstructures. 45 refs.
ISSN:1516-1439
1980-5373
1516-1439
DOI:10.1590/S1516-14392006000400004