Effect of indenter geometry on controlled-surface-flaw fracture thoughness
Fracture toughness values obtained using both Knoop and Vickers-indentation-produced controlled surface flaws were compared as a function of indentation load for a well-characterized glass-ceramic material. At the same indentation load, Knoop cracks were larger than Vickers. As-indented K/sub c/ values calculated from fracture mechanics expressions for surface flaws were higher for Knoop flaws than Vickers, but both types gave low K/sub c/ values due to indentation residual stress effects. Analysis suggested that theoretical formalisms for indentation residual stress effects based on fracture mechanics solutions for a center-loaded penny crack in an infinite medium should apply to both indentation types. K/sub c/ values calculated using the residual stress approach were identical for Knoop and Vickers controlled surface flaws when a ''calibration'' value for a constant term in the expression for K/sub c/ was used for both indentation types.
- Research Organization:
- Los Alamos National Lab., NM
- OSTI ID:
- 6973368
- Journal Information:
- J. Am. Ceram. Soc.; (United States), Journal Name: J. Am. Ceram. Soc.; (United States) Vol. 66:4; ISSN JACTA
- Country of Publication:
- United States
- Language:
- English
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