Crack tip toughening by inclusions with pairs of shear transformations

Conference · Sun Jan 01 04:00:00 EST 1989

DOI:https://doi.org/10.1007/978-1-4613-8919-4_6· OSTI ID:5375804

Chang, S -J; Becher, P F ^[1]

---

1. Oak Ridge National Lab., TN (USA)

The deviatoric transformation strain of an inclusion is modeled by applying an equivalent distribution of dislocations along a surface which exhibits a discontinuous change in the transformation strains. This method is applied to qualitatively model the twin structures generated in transformation toughened ceramics. For this case, the transformation shear strain of the inclusion is assumed to consist of a number of symmetrical pairs of (twinning) shears in a rectangular grain. The elastic energy is derived and expressed in terms of elementary functions. With one pair of shears, the inclusion induced toughening effect in the presence of a crack is calculated by applying a recent solution of the crack-dislocation interaction problem. Numerical results show that the toughening due to the inclusion (as compared to that due to dilatation) is not negligible if the inclusion is located within a distance equal to several grain sizes from the crack tip. Moreover, the toughening depends strongly on the orientation of the inclusion relative to the crack. 14 refs., 7 figs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5375804
• Report Number(s): CONF-891208-1; ON: DE89007845
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
CERAMICS
CHALCOGENIDES
CRACK PROPAGATION
CRACKS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
EDGE DISLOCATIONS
INCLUSIONS
LINE DEFECTS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
SHEAR
STRAINS
TRANSFORMATIONS
TRANSITION ELEMENT COMPOUNDS
TWINNING
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES