| RefNo | EC/1987/45 |
| Previous numbers | Cert XXII, 95 |
| Level | Item |
| Title | Irwin, George Rankin: certificate of election to the Royal Society |
| Date | 1986 |
| Description | Certificate of Candidate for Election to Foreign Membership. Citation typed |
| Citation | During the brief period 1935-1936 Irwin published two papers on the mass ratio of lithium isotopes. His contribution during, and just after World War 2, was to experimental studies of penetration ballistics, combat damage to aircraft and development of new armour materials. He made a crucial contribution to the development of several non-metallic body armours which were successfully used in the Korean and Vietnam conflicts.
These experiences prompted Irwin to seek a framework of testing and analysis, recognising the reality that materials under strain tend to fracture by crack initiation and extension, and that components are rendered vulnerable to cracking by incorporation of crack-like defects. Belief in the existence of such a possible framework was nurtured by studies of the Comet 1 pressurised fuselage fractures, burst fractures of large turbo-generator rotors, and fractures of high-strength steel solid rocket propellant casings.
At RAE in 1920 and after, A A Griffith demonstrated that fractures from precracks in glass exhibited a crack length size dependence, and is credited with the origin of an important concept. He calculated the magnitude of the size effect on a basis of energy release for crack extension, and examined the possible link with solid-state surface tension, but it was left to Orowan and Irwin to recognise the important influences on fracture strength of a much larger surface work component arising from plastic deformation local to a crack tip.
By 1954 Irwin had conceived a linear theory of crack tip fields of elastic stress and strain, described by the Westergaard singularity in zones immediately surrounding those of a fracture process zone dominated by plasticity, being compatible with the earlier work of Griffith. In 1957 he published a significant paper in the Journal of Applied Mechanics which formed the genesis of linear elastic fracture mechanics (LEFM). This was followed in 1958 by the substantial contribution on Fracture to the Springer Encyclopaedia of Physics. In the next few years he was able with ingenuity to provide many solutions to crack field stress problems using classical mathematical methods. He was instrumental in persuading the American Society for Testing and Materials to convene the now well-known E24 Committee, which patiently developed and standardised appropriate methods of measurement for the new material property known as fracture toughness. He took a keen interest in further developments of non-linear treatments for application to yielding materials, but held consistently to the view that his own main task was to increase the refinement of the linear elastic methods, both of stress analysis and material property measurement.
George Irwin has travelled widely to learn and contribute to research on LEFM, and is well-known in Britain and in Europe. He has been extensively honoured in the USA and abroad as the originator of LEFM, which is now widely taught to undergraduates in metallurgy and engineering. He has occupied the central position at at least one Conference on Fracture organised by the Royal Society, and it is proposed that he should be considered as a candidate for Foreign Membership. At the age of 79 he continues to be active in his original field. |
| AccessStatus | Closed |
Fellows associated with this archive
| Code | PersonName | Dates |
| NA3625 | Irwin; George Rankin (1907 - 1998) | 1907 - 1998 |