Microstructure-Properties: I Fracture Toughness - Materials Science ...
Microstructure-Properties: I Fracture Toughness - Materials Science ...
Microstructure-Properties: I Fracture Toughness - Materials Science ...
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22<br />
Objective<br />
Overview<br />
Crack<br />
Minimztn.<br />
Energy<br />
Absrptin.<br />
1 Crack deflection<br />
• If particles of a second phase are present, large differences in<br />
elastic modulus can either attract or repel the crack.<br />
• Some authors (e.g. Green) distinguish between crack bowing<br />
and crack deflection. Technically, the former is toughening<br />
from deflection in the plane of the crack and the latter is<br />
deflection out of the plane of the crack.<br />
• In either case, the net result is that the crack tip no longer<br />
sees as large a stress as it would if the crack were straight,<br />
and in the plane.<br />
• Crack deflection can be caused by particles that are more<br />
resistant to cracking, or have different elastic stiffness (higher<br />
or lower modulus).<br />
• Laminate composites also achieve crack deflection, as<br />
previously discussed.
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