SEDL / STP / STP627-EB / STP27389S

Characteristics of a Run-Arrest Segment of Crack Extension

Crosley, PB
Principal scientist and director of research, Materials Research Laboratory, Inc., Glenwood, Ill.

Ripling, EJ
Principal scientist and director of research, Materials Research Laboratory, Inc., Glenwood, Ill.

Pages: 25    Published: Jan 1977

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Abstract

During a run-arrest segment of crack extension, the crack attains a high velocity shortly after initiating, and then decelerates in a continuous fashion to arrest.

Strain measurements made during the event show that over the early portion of the jump when the crack velocity is high, the specimen behavior requires a dynamic analysis. During the later portions of the jump, when the velocity is low, the specimen behavior is described adequately by an analysis that assumes a condition of static equilibrium. Hence, if the dependence of a on K for the test material is described by a gamma (Γ) shaped curve, the crack arrest toughness, K^Ia, is an adequate description of K^Im, the minimum toughness for stable crack extension.