On the contribution of G. R. Irwin to fracture mechanics

Abstract

This is a brief survey of the scientific biography and works of George Rankine Irwin (born on February 26, 1907 in El Paso, Texas)—outstanding American scientist in the field of fracture mechanics and strength of materials, a Member of the American National Academy of Engineering, Royal Society of London, an Honorary Member and winner of prizes and awards of many American and European scientific societies. G. R. Irwin attended and graduated from Knox College and the University of Illinois where he won his Ph.D. degree. From 1936 till 1967, he worked in the US Naval Research Laboratory and in 1972, he became a Professor of Lehigh University and the University of Maryland where he now works. On the basis of his own experiments and the results of other researchers, G. R. Irwin suggested fundamentally new modification of the Griffith theory of brittle fracture and generalized this theory to the case of quasibrittle materials (see [2] and subsequent works). He introduced the concept of effective surface energy (1) and reformulated the Griffith theory in terms of singular stresses at the crack front and proved that his approach is equivalent to the Griffith energy approach [8]. He introduced stress intensity factors, i.e., parameters which relate the local mechanical state near the crack tip to macroscopic characteristics (such as the geometry of a body and loading) and enable one to give a very simple description of fracture processes as a continuous process of stable crack growth up to the onset of instability. His ideas very important for practical use and subsequent works devoted to their improvement and development caused a decisive influence on the progress in fracture mechanics as a new science and powerful engineering tool applicable to numerous problems connected with manufacturing and processing of materials and their failureproof operation in critical structures of various materials. By his works, Irwin initiated investigation of various aspects of the theory of fracture such as the role of plasticity, dynamics of the process, fractographic analysis of crack growth, etc. He also gave much attention to the development of new test methods for the determination of the characteristics of crackgrowth resistance of structural materials and their application. In recognition of Irwin's fundamental contribution to fracture mechanics, its fundamentals are now called the Griffith-Irwin theory (concept). A list of selected works by G. R. Irwin is given at the end of the present paper.