Crack‐Interface Grain Bridging as a Fracture Resistance Mechanism in Ceramics: II, Theoretical Fracture Mechanics Model

A fracture mechanics model is developed for nontransforming ceramics that show an increasing toughness with crack extension ( R ‐curve, or T ‐curve, behavior). The model derives from the observations in Part I, treating the increased crack resistance as the cumulative effect of grain bridging restraints operating behind the advancing tip. An element of discreteness is incorporated into the formal distribution function for the crack‐plane...