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Indentation‐Precracking and Double‐Torsion Methods for Measuring Fracture Mechanics Parameters in Hot‐Pressed Si 3 N 4
Author(s) -
GOVILA R. K.
Publication year - 1980
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.1151-2916.1980.tb10730.x
Subject(s) - indentation , torsion (gastropod) , materials science , iif , fracture mechanics , stress intensity factor , composite material , medicine , surgery , biology , antibody , immunology , autoantibody
The two widely used test methods, the indentation‐induced flaw (IIF) and the double‐torsion (DT), for measuring fracture mechanics parameters were directly compared using a commercial hot‐pressed Si 3 N 4 . The IIF method is simple for estimating the inherent flaw size of the as‐received material and in revealing the qualitative nature of slow crack growth as a function of temperature and strain rate. The critical stress intensity factor, K ic , for catastrophic failure at 20°C was 3.5 and 4.1 MN/m 3/2 using IIF and DT methods, respectively. Crack velocities can be measured with greater accuracy using the DT method.