Accession Number:

ADA235591

Title:

Three Dimensional Analysis of Crack Trapping and Bridging by Tough Particles

Descriptive Note:

Final rept.

Corporate Author:

BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING

Personal Author(s):

• Ortiz, M.

Report Date:

1991-04-01

Pagination or Media Count:

66.0

Abstract:

Ceramics have several properties that make them appealing materials for a wide range of practical applications. Since their strength is limited by brittle failure, the fracture of ceramics has been the subject of extensive research. However, despite recent progress in the area, a number of issues remain unresolved. For example, while the measured toughness of single crystals is comparable to their surface energy, that of polycrystalline materials is found to be up to an order of magnitude greater. In addition, the apparent toughness of the material is observed to increase with crack length. Three mechanisms have been proposed that may explain this behaviour crack tip shielding by microcracking crack deflection and crack trapping combined with crack face bridging by tough particles. The possibility that microcracking may improve toughness has recently been the subject of intense investigation. Extensive microcracking is fact observed around the tips of cracks in brittle polycrystalline materials. The microcracks increase the compliance of the solid, and so shield the crack tip from remote stresses.

Descriptors:

• *MATERIALS
• INTENSITY
• DEFLECTION
• SINGLE CRYSTALS
• TOUGHNESS
• FRACTURE(MECHANICS)
• THREE DIMENSIONAL
• CERAMIC MATERIALS
• BRITTLENESS
• PARTICLES
• LENGTH
• SHIELDING
• RANGE(EXTREMES)
• FAILURE(MECHANICS)
• BRIDGES
• POLYCRYSTALLINE
• SURFACE ENERGY
• MICROCRACKING
• CRACKS

Subject Categories:

• Ceramics, Refractories and Glass

Distribution Statement:

APPROVED FOR PUBLIC RELEASE