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Mixed‐Mode Fracture of Hot‐Pressed Si 3 N 4
Author(s) -
PETROVIC JOHN J.
Publication year - 1985
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.1151-2916.1985.tb15238.x
Subject(s) - materials science , composite material , indentation , mixed mode , stress intensity factor , fracture (geology) , fracture mechanics , bending , torsion (gastropod) , medicine , surgery
The mixed‐mode fracture of hot‐pressed Si 3 N 4 was investigated using inclined indentation surface flaws in bending and large crack geometries in combined tension/torsion. Non‐coplanar fracture was observed in all cases. Values of K Ic , K IIc , and K IIIc stress intensity factors were obtained, with ratios K IIc /K Ic = 0.79 and K IIIc /K Ic = 1.55 observed. For large cracks, mode II conditions had more of an effect on mode I fracture than mode III conditions. The mixed‐mode I‐II fracture of surface flaws was significantly different from that for large cracks, suggesting surface flaw shear resistance effects. A model describing these effects was derived, based on the ratio of the crack‐opening displacement to the crack surface asperity height.