George Rankin Irwin ForMemRS[1] (February 26, 1907 – October 9, 1998) was an American scientist in the field of fracture mechanics and strength of materials.
The Griffith approach was global and could not easily be extended to accommodate structures with finite geometries subjected to various types of loadings.
The theory was considered to apply only to a limited class of extremely brittle materials, such as glasses or ceramics.
Irwin observed that the fracture process in metals involved nonelastic work at the crack tip.
This observation permitted him to modify the Griffith theory by incorporating a plastic work of fracture in addition to the classical surface energy of crack formation.
In his tenure, he continued his collaboration with Paris, and collaborated with, influenced, or assisted many notable individuals in the fracture mechanics community, including: After retiring from Lehigh University in 1972, Irwin joined the faculty of the University of Maryland, College Park where he worked in the field of dynamic fracture, specifically concerned with crack arrest and the implications in a loss-of-coolant accident in a nuclear power plant.