SEDL / STP / STP1184-EB / STP18117S

Fatigue Crack Growth Behavior of Surface Cracks in Silicon Nitride

Mutoh, Y
Nagaoka University of Technology,

Takahashi, M
Nagaoka University of Technology,

Kanagawa, A
Nagaoka University of Technology,

Pages: 13    Published: Jan 1994

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Abstract

Cyclic fatigue crack growth tests of silicon nitride specimens with surface cracks as well as through-the-thickness cracks were carried out. The surface crack length was measured by a surface film gage technique. The fatigue crack growth rate for surface cracks was less than that for through-the-thickness cracks. From SEM observations, more significant bridging was found in the wake of surface cracks compared to through-the-thickness cracks. From evaluations of the stress shielding effect due to bridging based on the measurements of the crack mouth opening displacement, it was found that the crack growth curve determined from the crack tip stress intensity factor K^tip for surface cracks almost coincided with that for through-the-thickness cracks.