Thin components made from advanced brittle glasses or ceramics are becoming increasingly important due to the widespread adoption of portable consumer products as well as other modern electronic and medical devices. The strength of these brittle materials is traditionally estimated from empirical relationships relating the stress at failure to characteristic lengths derived from the fracture surface's topography. One example is Orr's relationship which correlates the material strength to the radios of the "mirror-mist boundary region," through the empirical constant Am. Although various studies have shown that, for flexural fractures (failed in bending), Am depends on the specimen's geometry, this effect has been generally neglected by arguing that the magnitude of Am is almost constant for thicker specimens. However, this paper sows that this argument cannot be applied to thin geometries, and that by not accounting for the thickness of the sample, the flexural strength will be grossly underestimated. This work introduces an expression based on an interactive fracture mechanics algorithm which yields more accurate estimates of flexural strength for thin brittle components in bending. The accuracy of the model is validated both through flexural strength tests on glass and by comparing predictions to an extensive literature survey of experimental results.
