The Strength of Glass

JSGT_1933_V17_T260_T272

The paper discusses the strength of glass with reference to the surface condition. Experiments on the thermal endurance of scratched bottles are quoted which demonstrate that scratches greater in magnitude than those deduced to be present by Griffith lower the thermal endurance, whereas smaller scratches do not affect this property. Methods of reducing the effect of surface flaws by fusing substances on glass surfaces are also discussed. The strength of glass is regarded as dependent on the chance of a surface flaw being correctly oriented to the principle stress, and the theory is applied to the thermal endurance of glass rods. It is deduced that the phenomenon of fatigue under repeated alternating stresses should not be shown by glass, and that strong glasses should have weakly defined Transition Points. The conditions for making a “strong” glass are also briefly discussed.

J. B. Murgatroyd