SEDL / STP / STP745-EB / STP28294S

Experimental Observation of Crack Velocity and Crack Front Shape Effects in Double-Torsion Fracture Mechanics Tests

Michalske, TA
Ceramic engineer, National Bureau of Standards, Washington, D.C.,

Singh, M
Mechanical engineer, Turbodyne Corp., Wellsville, N.Y.

Frechette, VD
Professor, N.Y.S. College of Ceramics, Alfred University, Alfred, N.Y.

Pages: 10    Published: Jan 1981

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Abstract

The double-torsion test configuration has been used to obtain crack growth information for a variety of materials. Recently critical reviews have suggested that certain assumptions used in the interpretation of double-torsion data are of questionable validity.

This paper presents experimental data for crack growth in glass specimens loaded in the double-torsion test configuration. The constant displacement rate technique was used to propagate cracks and velocity was measured continuously by superimposing a tuned-frequency sonic signal during cracking. The crack velocity profile as a function of position along the crack front was determined. The crack velocity at the tensile surface was measured as a function of crack length at constant load and the crack front shape was observed for various crack lengths.