Mechanism of Brittle Rupture

Abstract

THE low strength of brittle materials has been ascribed by A. A. Griffith¹ to the presence of discontinuities which have the properties of small cracks in these materials. Since this theory was published, however, several investigations have established the fact that glass exhibits the phenomenon of delayed rupture to a marked degree, and this is not easily explicable by Griffith's theory alone. The most recent of these investigations, by F. W. Preston² in the United States, reports the variation in strength of glass when loads are applied for periods of 10^–2 sec. up to 10⁵ sec., the breaking stress falling from 14·3 kgm./mm.² for 10^–2 sec. duration of load to 4·47 kgm./mm.² for 10⁵ sec. duration.