Effects of precracking methods on the fracture properties of aluminaFracture toughness values were compared for quasi-statically cracked, rapidly precracked, and fatigue precracked specimens of the same 96 percent alumina. The quasi-statically cracked specimens exhibited a rising R-curve and crack length dependent fracture toughness values. The rising R-curve resulted from grain bridging in the crack wake. Tension and compression fatigue precracked specimens did not exhibit crack length dependence, but did produce consistent fracture toughness values from fast fracture tests. Specimens that were rapidly precracked with the bridge indentation method also did not exhibit crack length dependence. These results imply that the measured fracture toughness and observed crack growth resistance of some brittle ceramics are dependent on loading history, crack extension and environment.
Document ID
19930032648
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Salem, Jonathan A. (NASA Lewis Research Center Cleveland, OH, United States)
Shannon, John L., Jr. (NASA Lewis Research Center Cleveland, OH, United States)
Jenkins, Michael G. (NASA Lewis Research Center Cleveland, OH, United States)
Ferber, Mattison K. (Oak Ridge National Lab. TN, United States)
Date Acquired
August 15, 2013
Publication Date
January 1, 1991
Publication Information
Publication: In: 1991 SEM Spring Conference on Experimental Mechanics, Milwaukee, WI, June 10-13, 1991, Proceedings (A93-16601 04-39)
Publisher: Society for Experimental Mechanics, Inc.