Fracture toughness of brittle materials determined with chevron notch specimensShort bar, short rod, and four-point-bend chevron-notch specimens were used to determine the plane strain fracture toughness of hot-pressed silicon nitride and sintered aluminum oxide brittle ceramics. The unique advantages of this specimen type are: (1) the production of a sharp natural crack during the early stage of test loading, so that no precracking is required, and (2) the load passes through a maximum at a constant, material-independent crack length-to-width ratio for a specific geometry, so that no post-test crack measurement is required. The plane strain fracture toughness is proportional to the maximum test load and functions of the specimen geometry and elastic compliance. Although results obtained for silicon nitride are in good mutual agreement and relatively free of geometry and size effects, aluminum oxide results were affected in both these respects by the rising crack growth resistance curve of the material.
Document ID
19810048141
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Shannon, J. L., Jr. (NASA Lewis Research Center Cleveland, OH, United States)
Bubsey, R. T. (NASA Lewis Research Center Cleveland, OH, United States)
Pierce, W. S. (NASA Lewis Research Center Cleveland, Ohio, United States)
Munz, D. (Karlsruhe, Universitat; Kernforschungszentrum Karlsruhe GmBH, Karlsruhe, Germany)