Tensile fracture behavior of two types of silicon nitride specimen geometries conducted by ten U.S. groups
The work reported was conducted to provide a basis for structural ceramic mechanical property standardization activities under way in the US, Germany, Japan, and Sweden. All measurements reported here were conducted by 10 US groups on GN-10 silicon nitride within an International Energy Agency program including the US, Germany, Japan, and Sweden. This cooperative work included tensile strength studies of two geometries of button-head tensile specimens. The authors conducted some of the measurements and performed data analyses and interpretation. The tensile fracture behavior of GN-10 silicon nitride was studied at room temperature. A total of 150 strain-gaged button-head tensile specimens were measured. One hundred of a straight collet design and 50 of a tapered collet design were fractured. All specimens were highly strain gaged and the outputs for each were measured during loading to fracture. Bending moments were calculated. Analysis of the Weibull m and {sigma}{sub {Theta}} estimators at upper and lower confidence bounds of 95% and 5% did not indicate a clear choice between the two designs. For specimens which fractured in the gage section, the unbiased maximum likelihood Weibull estimators for m and {sigma}{sub {Theta}} were 12.5 and 730 and 10.4 and 716, for the straight and tapered collet configurations, respectively. These are not statistically different at the 95% and 5% confidence levels. Strengths were also analyzed in terms of a three-parameter Weibull model. The straight collet specimen data fitted the three parameter model well with a threshold stress estimator {gamma} of 506 MPa, while the tapered collet specimens provided a poorer fit to the model and had a threshold stress estimator of 432 MPa, a difference of about 15%.
- Research Organization:
- Oak Ridge National Lab., TN (US)
- OSTI ID:
- 20075976
- Journal Information:
- Journal of the American Ceramic Society, Vol. 83, Issue 5; Other Information: PBD: May 2000; ISSN 0002-7820
- Country of Publication:
- United States
- Language:
- English
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