SEDL / STP / STP1207-EB / STP13729S

Fracture Criteria for Surface Cracks in Brittle Materials

Reuter, WG
Principal engineer, Idaho National Engineering Lab., EG&G Idaho, Idaho Falls, ID

Newman, JC
Senior scientist, NASA-Langley Research Center, Hampton, VA

Macdonald, BD
Principal engineer, Knolls Atomic Power Lab., Schenectady, NY

Powell, SR
Engineering specialist, Bell Helicopter Textron, Fort Worth, TX

Pages: 19    Published: Jan 1994

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Abstract

If a structural material behaves in a linearly elastic manner, it is generally assumed that plane-strain fracture toughness (K^Ic) and a proven equation for calculating an applied stress-intensity factor can be used to predict conditions for catastrophic fracture. The adequacy of this approach has been verified for some specific applications, generally through-cracks in plate material. Recent fracture test results and analyses of surface cracks in brittle materials have raised a concern about the validity of using K^Ic and the maximum value of the calculated stress-intensity factors to predict fracture conditions. This paper presents test data and results obtained from different procedures, all based on K^Ic, for predicting failure for three-dimensional surface cracks.