George Rankin Irwin (February 26, 1907 – October 9, 1998) was an American scientist in the field of

fracture mechanics Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics t ...

and

strength of materials The field of strength of materials, also called mechanics of materials, typically refers to various methods of calculating the stresses and strains in structural members, such as beams, columns, and shafts. The methods employed to predict the re ...

. He was internationally known for his study of fracture of materials.

Early life and education

George R. Irwin was born in

El Paso, Texas El Paso (; "the pass") is a city in and the county seat, seat of El Paso County, Texas, El Paso County in the western corner of the U.S. state of Texas. The 2020 population of the city from the United States Census Bureau, U.S. Census Bureau w ...

. His family moved to

Springfield Springfield may refer to: * Springfield (toponym), the place name in general Places and locations Australia * Springfield, New South Wales (Central Coast) * Springfield, New South Wales (Snowy Monaro Regional Council) * Springfield, Queenslan ...

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

where he went to school. He attended Knox College in

Galesburg, Illinois Galesburg is a city in Knox County, Illinois, United States. The city is northwest of Peoria. At the 2010 census, its population was 32,195. It is the county seat of Knox County and the principal city of the Galesburg Micropolitan Statistical ...

and earned an A.B. degree in English in 1930. After an additional year studying physics, he transferred to the

University of Illinois at Urbana-Champaign The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the Univ ...

where he studied from 1931 to 1935. He received his Ph.D. from the University of Illinois in 1937; his thesis was on the

mass ratio In aerospace engineering, mass ratio is a measure of the efficiency of a rocket. It describes how much more massive the vehicle is with propellant than without; that is, the ratio of the rocket's ''wet mass'' (vehicle plus contents plus propellan ...

lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid el ...

isotopes Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

Career

In 1937 he joined the

US Naval Research Laboratory The United States Naval Research Laboratory (NRL) is the corporate research laboratory for the United States Navy and the United States Marine Corps. It was founded in 1923 and conducts basic scientific research, applied research, technological ...

(NRL) in

Washington D.C. ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, Na ...

where he worked until 1967. There he worked on

ballistics Ballistics is the field of mechanics concerned with the launching, flight behaviour and impact effects of projectiles, especially ranged weapon munitions such as bullets, unguided bombs, rockets or the like; the science or art of designing and a ...

, specifically on the mechanics of

projectiles A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found in ...

penetrating targets. Here he developed methods for determining the penetration force that a projectile exerts on its target. This work was completed throughout the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. Part of this work led to the development of several

nonmetallic In chemistry, a nonmetal is a chemical element that generally lacks a predominance of metallic properties; they range from colorless gases (like hydrogen) to shiny solids (like carbon, as graphite). The electrons in nonmetals behave differentl ...

armors (see

vehicle armor Military vehicles are commonly armoured (or armored; see spelling differences) to withstand the impact of shrapnel, bullets, shells, rockets, and missiles, protecting the personnel inside from enemy fire. Such vehicles include armoured fighting ...

). This coupled with his observation that thick armor plate made from

ductile Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stres ...

material (such as

steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...

) failed in a brittle manner during test firings initiated his interest in

brittle fracture Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displa ...

. In 1946 he was made responsible for the project on brittle fracture at the NRL and in 1948 he was promoted from the head of the Ballistics Branch of the NRL to associate superintendent of the Mechanics Division. In 1950 he was again promoted to superintendent of the Mechanics Division. He served in that capacity until his retirement from government service in 1967. The classical approach to brittle fracture in the late 1940s had been developed in the early 1920s, following the work of A. A. Griffith. Griffith had shown that an instability criterion could be derived for cracks in brittle materials based on the variation of potential energy of the structure as the crack grew. The Griffith approach was global and could not easily be extended to accommodate

structures A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

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

glass Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of ...

es or

ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...

s. Irwin observed that the fracture process in metals involved nonelastic

work Work may refer to: * Work (human activity), intentional activity people perform to support themselves, others, or the community ** Manual labour, physical work done by humans ** House work, housework, or homemaking ** Working animal, an animal tr ...

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. As part of this work, Irwin defined the fundamental concept of a ''

Stress Intensity Factor In fracture mechanics, the stress intensity factor () is used to predict the stress state ("stress intensity") near the tip of a crack or notch caused by a remote load or residual stresses. It is a theoretical construct usually applied to a h ...

'' and the critical plane-strain stress intensity factor (KIC) which is a

material property A materials property is an intensive property of a material, i.e., a physical property that does not depend on the amount of the material. These quantitative properties may be used as a metric by which the benefits of one material versus another c ...

. He was involved in the development of several standards and led several committees for the

American Society for Testing and Materials ASTM International, formerly known as American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, an ...

(ASTM). In 1967, Irwin was recruited to

Lehigh University Lehigh University (LU) is a private research university in Bethlehem, Pennsylvania in the Lehigh Valley region of eastern Pennsylvania. The university was established in 1865 by businessman Asa Packer and was originally affiliated with the Epis ...

as the Boeing University Professor by long-time collaborator

Paul C. Paris Paul Croce Paris (August 7, 1930 - January 15, 2017) was an American academic, engineering consultant and researcher in the field of mechanics and fatigue. He was known particularly for introducing fracture mechanics methods to the aviation indust ...

, the father of modern methods for predicting crack growth and its control in aircraft structures. Irwin served for five years before reaching mandatory retirement age. In his tenure, he continued his collaboration with Paris, and collaborated with, influenced, or assisted many notable individuals in the fracture mechanics community, including: *F. Erdogan on cracks in thin-walled shell structures; *A. A. Wells of the British Welding Institute on characterizing fracture in normally ductile steel structures; *F. A. McClintock,

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the ...

and

John W. Hutchinson John W. Hutchinson (born April 10, 1939) is the Abbott and James Lawrence Research Professor of Engineering in the School of Engineering and Applied Sciences at Harvard University. He works in the field of solid mechanics concerned with a broad ...

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...

, on the development of fracture mechanics procedures in the presence of substantial ductility; * James R. Rice, Harvard University, on developing the J integral approach for characterizing the onset of crack growth in ductile materials; *L. B. Freund,

Brown University Brown University is a private research university in Providence, Rhode Island. Brown is the seventh-oldest institution of higher education in the United States, founded in 1764 as the College in the English Colony of Rhode Island and Providenc ...

, and M. F. Kanninen,

Southwest Research Institute Southwest Research Institute (SwRI), headquartered in San Antonio, Texas, is an independent and nonprofit applied research and development (R&D) organization. Founded in 1947 by oil businessman Tom Slick, it provides contract research and develop ...

, on the dynamics of inertial limited crack propagation and arrest. After retiring from Lehigh University in 1972, Irwin joined the faculty of the

University of Maryland, College Park The University of Maryland, College Park (University of Maryland, UMD, or simply Maryland) is a public land-grant research university in College Park, Maryland. Founded in 1856, UMD is the flagship institution of the University System of Mary ...

where he worked in the field of dynamic fracture, specifically concerned with crack arrest and the implications in a

loss-of-coolant accident A loss-of-coolant accident (LOCA) is a mode of failure for a nuclear reactor; if not managed effectively, the results of a LOCA could result in reactor core damage. Each nuclear plant's emergency core cooling system (ECCS) exists specifically t ...

in a

nuclear power plant A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a electric generator, generato ...

Memberships and honours

Irwin was a member of the America

National Academy of Engineering The National Academy of Engineering (NAE) is an American nonprofit, non-governmental organization. The National Academy of Engineering is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy ...

and a Foreign Member of the

Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

of London. Additionally, he received the following honours:- *1946 - Naval Distinguished Civilian Service Award *1947 - Knox College Alumni Achievement Award *1959 - ASTM Charles B. Dudley Medal *1960 - RESA Award for Applied Research *1961 - Ford Foundation Visiting Professorship, University of Illinois *1966 - ASTM Award of Merit *1966 - American Society of Mechanical Engineers (ASME) Thurston Lecture *1967 - Fellow, ASTM *1969 - University of Illinois Engineering Achievement Award *1969 - U. S. Navy Conrad Award *1969 - Alumni Achievement Award, University of Illinois *1973 - SESA Murray Lectureship Award *1974 - Lehigh University Academic Leadership Award *1974 - ASTM honorary member *1974 - American Society for Metals Sauveur Award *1976 - The Grande Medaille Award of the French Metallurgical Society of France *1977 - ASME Nadai Award *1977 - B. J. Lazan Award from the Society for Experimental Mechanics *1977 - Honorary degree, doctor of engineering, Lehigh University *1977 - Election to the National Academy of Engineering *1978 - ASTM-Irwin Award *1979 - Francis J. Clamer Clauier Medal of the Franklin Institute *1982 - Governor’s Citation for Distinguished Service to Maryland *1982 - Tetmajer Award of the Technical University of Vienna, Austria *1985 -

Fellow A fellow is a concept whose exact meaning depends on context. In learned or professional societies, it refers to a privileged member who is specially elected in recognition of their work and achievements. Within the context of higher education ...

Society for Experimental Mechanics Society for Experimental Mechanics (SEM) is a professional organization for engineers and scientists studying the design and implementation of experiments to characterize materials, structures, and systems. Formed in 1943 as the Society for Experim ...

*1986 - ASME

Timoshenko Medal The Timoshenko Medal is an award given annually by the American Society of Mechanical Engineers (ASME) to an individual "in recognition of distinguished contributions to the field of applied mechanics." The Timoshenko Medal, widely regarded as th ...

*1987 - ASM Gold Medal for Outstanding Contributions to Engineering and Science *1987 - Elected to foreign membership, British Royal Society *1988 - ASTM Fracture Mechanics Award and the George R. Irwin Medal *1989 - Honorary membership in Deutscher Verband für Material Prufung *1990 - Honorary membership in the American Ceramic Society *1990 - Albert Sauveur Lecture Award *1992 - George R. Irwin Research Award, University of Maryland *1993 - Engineering Innovation Hall of Fame at the University of Maryland *1998 - A. James Clark Outstanding Commitment Award University of Maryland *1998 - Appointed Glenn L. Martin Institute Professor of Engineering

References

Bibliography

*Dally, James W.,''George R. Irwin'', Memorial Tributes: National Academy of Engineering, Volume 10 (2002), p 146-153, National Academy of Engineering (NAE). http://darwin.nap.edu/books/0309084571/html/146.html {{DEFAULTSORT:Irwin, George Rankine 1907 births 20th-century American engineers University of Illinois Urbana-Champaign alumni Lehigh University faculty Members of the United States National Academy of Engineering 1998 deaths Foreign Members of the Royal Society Fellows of the Society for Experimental Mechanics Knox College (Illinois) alumni