PREDICTION OF THE STRENGTHS OF INTERNAL CAVITIES IN GLASS UNDER COMPRESSIVE LOADS.
NAVAL RESEARCH LAB WASHINGTON D C
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The compressive strength of bulk glass is limited by the tensile strength of the surfaces of internal cavities, especially clusters of cavities closely spaced so as to have strongly interacting stress fields. The tensile stress on the surfaces of single ellipsoids were taken from a previous report, and predictions of probabilities of failure were made based on an assumed Weibull distribution of strengths. Numerical values for Weibull coefficients were used which were believed to be representative of pristine glass but not homogenized by extended heat treatment. The predictions are thought to be somewhat conservative but could easily be adjusted in the light of better experimental data if and when they become available. The assumed m coefficients are believed to be realistic but the assumed sigmao, i.e., the strength of pristine bubbles of unit area at a probability of failure of 0.63, may need future revision. All predicted strengths are proportional to sigmao. Predicted strengths are shown graphically for probabilities of failure ranging from 10 to the -6th to 10 to the -1st. Author
- Ceramics, Refractories and Glass