George Rankin Irwin. 26 February 1907 — 9 October 1998

Alan A. Wells

Elected For.Mem.R.S. 1987


In the search for a criterion for the fracture of brittle materials by crack extension, George Irwin first identified the linear elastic stress intensity as a quantitative measure of the associated mathematical singularity, and then laid the foundation of a relevant stress analysis system. This permitted the significance of increased fracture toughness, section thickness and dynamic effects to be established.

There was much initial scepticism in the engineering and metallurgical communities, eventually countered successfully by sustained research and patient argument. Peer acceptance led in 1957 to the formation of the E24 Committee of the American Society for Testing and Materials, and the subsequent creation of a valuable series of handbooks, so that within a further decade linear elastic fracture mechanics (LEFM) had been additionally and successfully applied to fatigue and stress corrosion cracking. The definition and standardization of measurement specimen shapes and testing procedures opened the way to the development of strong metallic and non-metallic materials with improved fracture toughness properties, thereby leading to safer structures with improved performance. Despite cumulative complexities, fracture mechanics is now associated with a vast published literature and is applied extensively.