SYMPOSIA PAPER Published: 01 January 2002
STP10476S

Crack Deflection Toughening Mechanism in Brittle Materials

Source

Toughening mechanisms in polycrystalline ceramics and ceramic-based composites were discussed based on Griffith's energy equilibrium and classified into three groups: (A) the frontal process-zone toughening mechanism, (B) the crack-bridging mechanism, and (C) the macroscopic crack-deflection mechanism. The increase in fracture toughness caused by enforced macroscopic crack-deflection was estimated using the energy equilibrium between the energy-release rate and the fracture-energy rate. The analytical results revealed that the fracture toughness under Mode I loading was enhanced by twice the normal value when the crack propagates in the direction 90° from its original plane. Under Mode II loading the fracture toughness is increased 1.2 times the normal value when the crack propagates in its original plane. Crack-deflection tests were carried out by using wooden, thin rectangular plates with a central crack. The increase in the fracture toughness caused by crack deflection was confirmed and the experimental data was coincident with the calculated results.

Author Information

Awaji, H
Nagoya Institute of Technology, Nagoya, Japan
Ebisudani, M
Nagoya Institute of Technology, Nagoya, Japan
Choi, S-M
Nagoya Institute of Technology, Nagoya, Japan
Ohashi, T
Nagoya Institute of Technology, Nagoya, Japan
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Details
Developed by Committee: C28
Pages: 137–151
DOI: 10.1520/STP10476S
ISBN-EB: 978-0-8031-5461-2
ISBN-13: 978-0-8031-2880-4