Unformatted text preview: σ F ♦ true strain at failure, ε F Ceramics are more brittle than metals. Typically their TS <<<<< CS. The Griffith crack model explains why: All materials have elliptical cracks that experience a stress intensification at the crack tip given by: σ m = 2 σ (c/ ρ ) 1/2 Ceramics and glasses have a lot of these. A compressive load tends to close, not open the Griffith flaws. Hence, the CS is not affected, only the TS....
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- Spring '09