George Rankine Irwin
Encyclopedia
Dr. George Rankin Irwin FRS (February 26, 1907 – October 9, 1998) was an American
scientist in the field of fracture mechanics
and strength of materials
. He was internationally known for his study of fracture of materials.
. His family moved to Springfield
, Illinois
where he went to school.
He attended Knox College in Galesburg
, Illinois
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
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
of lithium
isotopes.
, specifically on the mechanics of projectiles 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. Part of this work led to the development of several nonmetallic armors (see vehicle armor). This coupled with his observation that thick armor plate made from ductile material (such as steel
) failed in a brittle manner during test firings initiated his interest in brittle fracture.
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 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
es or ceramic
s. 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.
As part of this work, Irwin defined the fundamental concept of a Stress Intensity Factor
and the critical stress intensity factor (KIC) which is a material property.
He was involved in the development of several standards and led several committees for the American Society for Testing and Materials (ASTM).
In 1967, Irwin was recruited to Lehigh University
as the Boeing University Professor by long-time collaborator Paul C. Paris, 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:
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
.
and a Foreign Member of the Royal Society
of London.
Additionally, he received the following honours:-
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
scientist in the field of fracture mechanics
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 to characterize the material's resistance to fracture.In...
and strength of materials
Strength of materials
In materials science, the strength of a material is its ability to withstand an applied stress without failure. The applied stress may be tensile, compressive, or shear. Strength of materials is a subject which deals with loads, deformations and the forces acting on a material. A load applied to a...
. He was internationally known for his study of fracture of materials.
Early life and education
George R. Irwin was born in El Paso, TexasEl Paso, Texas
El Paso, is a city in and the county seat of El Paso County, Texas, United States, and lies in far West Texas. In the 2010 census, the city had a population of 649,121. It is the sixth largest city in Texas and the 19th largest city in the United States...
. His family moved to Springfield
Springfield, Illinois
Springfield is the third and current capital of the US state of Illinois and the county seat of Sangamon County with a population of 117,400 , making it the sixth most populated city in the state and the second most populated Illinois city outside of the Chicago Metropolitan Area...
, Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
where he went to school.
He attended Knox College in Galesburg
Galesburg
Galesburg is the name of some places in the United States of America:*Galesburg, Illinois, the largest city in the US named Galesburg*Galesburg, Kansas*Galesburg, Michigan*Galesburg, North Dakota...
, Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
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
University of Illinois at Urbana-Champaign
The University of Illinois at Urbana–Champaign is a large public research-intensive university in the state of Illinois, United States. It is the flagship campus of the University of Illinois system...
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
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, it is the ratio of the rocket's wet mass to its dry mass...
of lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
isotopes.
Career
In 1937 he joined the US Naval Research Laboratory (NRL) in Washington D.C where he worked until 1967. There he worked on ballisticsBallistics
Ballistics is the science of mechanics that deals with the flight, behavior, and effects of projectiles, especially bullets, gravity bombs, rockets, or the like; the science or art of designing and accelerating projectiles so as to achieve a desired performance.A ballistic body is a body which is...
, specifically on the mechanics of projectiles 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. Part of this work led to the development of several nonmetallic armors (see vehicle armor). This coupled with his observation that thick armor plate made from ductile material (such as steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
) failed in a brittle manner during test firings initiated his interest in brittle fracture.
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 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
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
es or ceramic
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
s. Irwin observed that the fracture process in metals involved nonelastic work
Mechanical work
In physics, work is a scalar quantity that can be described as the product of a force times the distance through which it acts, and it is called the work of the force. Only the component of a force in the direction of the movement of its point of application does work...
at the crack tip. This observation permitted him to modify the Griffith theory
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 to characterize the material's resistance to fracture.In...
by incorporating a plastic work of fracture in addition to the classical surface energy of crack
Fracture
A fracture is the separation of an object or material into two, or more, pieces under the action of stress.The word fracture is often applied to bones of living creatures , or to crystals or crystalline materials, such as gemstones or metal...
formation.
As part of this work, Irwin defined the fundamental concept of a Stress Intensity Factor
Stress Intensity Factor
The stress intensity factor, K, is used in fracture mechanics to predict the stress state near the tip of a crack caused by a remote load or residual stresses. It is a theoretical construct usually applied to a homogeneous, linear elastic material and is useful for providing a failure criterion...
and the critical stress intensity factor (KIC) which is a material property.
He was involved in the development of several standards and led several committees for the American Society for Testing and Materials (ASTM).
In 1967, Irwin was recruited to Lehigh University
Lehigh University
Lehigh University is a private, co-educational university located in Bethlehem, Pennsylvania, in the Lehigh Valley region of the United States. It was established in 1865 by Asa Packer as a four-year technical school, but has grown to include studies in a wide variety of disciplines...
as the Boeing University Professor by long-time collaborator Paul C. Paris, 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 TechnologyMassachusetts Institute of TechnologyThe Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
and John W. HutchinsonJohn W. HutchinsonJohn W. Hutchinson is a renowned scholar in the field of applied mechanics, and has made seminal contributions to the mechanics of structures and mechanics of materials. He is a recipient of the Timoshenko Medal...
, Harvard UniversityHarvard UniversityHarvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
, on the development of fracture mechanics procedures in the presence of substantial ductility; - James R. RiceJames R. RiceJames Robert Rice is a mechanician who has made fundamental contributions to various aspects of solid mechanics. Two of his early contributions are the concept of the J-integral and an explanation of how plastic deformations localize in a narrow band. In recent years, Rice has focused on the...
, Harvard University, on developing the J integralJ integralThe J-integral represents a way to calculate the strain energy release rate, or work per unit fracture surface area, in a material. The theoretical concept of J-integral was developed in 1967 by Cherepanov and in 1968 by Jim Rice independently, who showed that an energetic contour path integral ...
approach for characterizing the onset of crack growth in ductile materials; - L. B. Freund, Brown UniversityBrown UniversityBrown University is a private, Ivy League university located in Providence, Rhode Island, United States. Founded in 1764 prior to American independence from the British Empire as the College in the English Colony of Rhode Island and Providence Plantations early in the reign of King George III ,...
, and M. F. Kanninen, Southwest Research InstituteSouthwest Research InstituteSouthwest Research Institute , headquartered in San Antonio, Texas, is one of the oldest and largest independent, nonprofit, applied research and development organizations in the United States...
, 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
University of Maryland, College Park
The University of Maryland, College Park is a top-ranked public research university located in the city of College Park in Prince George's County, Maryland, just outside Washington, D.C...
where he worked in the field of dynamic fracture
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 to characterize the material's resistance to fracture.In...
, specifically concerned with crack arrest and the implications in a loss-of-coolant accident in a nuclear power plant
Nuclear power plant
A nuclear power plant is a thermal power station in which the heat source is one or more nuclear reactors. As in a conventional thermal power station the heat is used to generate steam which drives a steam turbine connected to a generator which produces electricity.Nuclear power plants are usually...
.
Memberships and honours
Irwin was a member of the America National Academy of EngineeringNational Academy of Engineering
The National Academy of Engineering is a government-created non-profit institution in the United States, that was founded in 1964 under the same congressional act that led to the founding of the National Academy of Sciences...
and a Foreign Member of the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
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, Society for Experimental Mechanics
- 1986 - ASME Timoshenko MedalTimoshenko MedalThe Timoshenko Medal is an award given annually by the American Society of Mechanical Engineers to an individual"in recognition of distinguished contributions to the field of applied mechanics."...
- 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