Memorial Tributes: Volume 26
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  • GEORGE J. DVORAK (1933-2022)
    GEORGE J. DVORAK

     

    BY ZDENĚK P. BAŽANT, HANCHEN HUANG, MARY ELLEN CLARK, AND JIŘÍ NÁPRSTEK

    GEORGE J. DVORAK passed away peacefully at his home in Menands, New York, on April 23, 2022, at the age of 88. He was an accomplished scholar and a member of the US National Academy of Engineering, which positioned him among roughly 2000 of the most prominent living engineering professionals in the United States.

    George Dvorak was born in Prague on October 26, 1933, and grew up in what was then Czechoslovakia, where he was known as Jiří Dvořák until he emigrated. After the war, he attended a high school in Teplice and, in 1951, he entered the School of Civil Engineering of the Czech Technical University in Prague. There, he majored in steel structures, studying under the guidance of Professor František Faltus, and worked as a welding instructor in steel structures courses. In 1957, after graduating with the degree of civil engineer (“Ing.,” in Czech), he became an instructor in the Mechanics Department of the Technical University in Liberec, where he taught kinematics, statics, and dynamics of mechanisms to mechanical engineering students. While at the Technical University, he met prominent mathematician Alois Švec, with whom he wrote a book on the kinematics-based generation of technical curves. That book was published in Prague in 1962.

    Returning to Prague in 1959, Dvorak started his graduate studies at the Institute of Theoretical and Applied Mechanics at the Czechoslovak Academy of Science under the advisorship of Professor Faltus. He focused on the experimental investigation of the effect of surface embrittlement on brittle fracture initiation in low-alloy steels. In 1964, after defending his dissertation, Dvorak was awarded the degree of candidate of science (CSc, the equivalent of a PhD). The same year, he was delegated to give the opening lecture at the Congress of the International Institute of Welding, held in Prague. This led to an invitation to the United States that, after he overcame various obstacles, provided him an opportunity to escape communism. He did not return to his native country until after the fall of communism in 1989. For twenty-five years, Dvorak could not have any contact with the scholars in Czechoslovakia.

    He began his American career as a research associate at Brown University, where he arrived in November 1964. In his first year at Brown, George Dvorak worked under the advisorship of Professor Constantine Mylonas on the brittle fracture of ship steels associated with the ‘‘exhaustion of ductility’’ effect caused by hot or cold plastic compression. Then he entered graduate study under the advisorship of Professor Daniel C. Drucker (NAE 1967), graduating from Brown with his second PhD in 1968. By 1967, he had already launched his teaching career at Duke University, where he initiated his enduring interest in the mechanics of composite materials.

    In 1979, following in the footsteps of several prominent administrators in his family line, he became the chairman of the Civil Engineering Department at the University of Utah in Salt Lake City. His main research results in those years laid the foundation for the theory of uniform fields in fibrous heterogeneous solids and its subsequent applications in formulating the exact connections between the phase and overall elastic moduli and other physical properties, including the thermomechanics of composite materials.  Additionally, Dvorak and his associates initiated and completed an extensive experimental program on the plastic deformation of metal matrix laminates under combined in-plane loads in the laboratory of Professor Aris Phillips at Yale University.

    In 1984, Dvorak became chairman of the Department of Civil Engineering at Rensselaer Polytechnic Institute (RPI) in Troy, New York, a position he held for seventeen years. At RPI, he held the prestigious chair of William Howard Hart Professor of Mechanics. From 1988–1997, while at RPI, Dvorak directed NASA’s composites center and sequential university research initiative programs on structural and high-temperature composite materials.

    Even as Dvorak fulfilled his duties as department chair, his tenure at RPI was very productive, leading to numerous theoretical and experimental papers and hundreds of lectures on the micromechanics of inelastic deformation, the damage evolution and fracture of composite materials, and the modeling of functionally graded composites. During this period, Dvorak developed his now well-known theory of uniform fields in heterogeneous materials with transformation field analysis (TFA). 

    Professor Dvorak’s main contribution was in the modeling of elastic and elastoplastic composite materials, including the effects of transverse isotropy, stress, and thermoelastic damping. He found how the composite structure, laminate layup, and fibrous reinforcement are connected with micromechanics and other disciplines. His major accomplishment—the method of uniform fields—is an effective method for calculating the equivalent macro-continuum properties. He rigorously presented this method in his book, Micromechanics of Composite Materials (Springer, 2013). This work facilitated computational implementation in the finite element method and enabled stiffness and stability assessments of composite structures, taking into account the effects of fiber reinforcement, material hardening, and stress concentrations. Dvorak’s book was the pinnacle of his career.

    Professor Dvorak spent nearly a quarter of a century at RPI and retired in 2008. For various periods of time during his tenure at RPI, he was a visiting professor at the Polytechnic University of Milan, at the University of Cambridge, at Yale University, and at the Technical University of Denmark. After his retirement from his position at RPI, he served as a research visiting professor at the University of Connecticut and at the University of North Texas. Until 2010, he was an adjunct professor in the Department of Civil and Environmental Engineering at Northwestern University, where he collaborated with his longtime friend Zdeněk P. Bažant on the aging creep of concrete treated as a particulate composite.

    Professor Dvorak served in several leadership roles in American academia. He was president of the Society of Engineering Science from 1988 to 1989. In 1985, he served as chair of the Engineering Mechanics Division of the American Society of Civil Engineers (ASCE). He received numerous honors and awards, including the Medal of Merit for Contributions to the Development of Mechanics from the Czechoslovak Academy of Science in 1992, the 1992 Nadai Medal from the American Society of Mechanical Engineers (ASME) for pioneering research in the mechanics of modern materials, the 1994 Prager Medal from the Society of Engineering Science (SES) for outstanding contributions to the mechanics of solids, the 1995 Fulbright Fellowship to the Technical University of Denmark, a 1997 degree of doctor honoris causa from the Czech Technical University in Prague, the 1999 Brown Engineering Alumni Medal, and the 2002 Daniel C. Drucker Medal from ASME for research achievements in plasticity, material fracture and fatigue, and thermo-mechanics of heterogeneous materials. A special issue of the International Journal of Solids and Structures (vol. 40, no. 25), edited by Z.P. Bažant, was published in honor of Professor Dvorak in 2003. In 2006, he received the ASCE Theodore von Karman Medal for fundamental contributions to the mechanics of material behavior, including the micromechanics of fracture and fatigue of composite materials and structures.

    In addition to mentoring many PhD students, postdocs, and visiting researchers, Professor Dvorak has been a beloved mentor to his junior colleagues. One of his junior colleagues at RPI, Hanchen Huang, now the provost of the University of Massachusetts at Dartmouth, continued to collaborate with him and remained in continuous contact with him throughout the early 2000s. Huang has fond memories of being mentored by Professor Dvorak.

    Professor Dvorak’s survivors include his longtime companion, Mary Ellen Clark, and his son, George Dvorak Jr. Professor Dvorak is buried at Albany Rural Cemetery near Albany, NY.

    The American and worldwide mechanics research communities have suffered an irreplaceable loss due to the passing of this world-renowned expert, whose monumental body of work will be remembered with great respect. Beyond his invaluable contributions, equipped with quick wit and dry humor, George was an excellent companion in conversation; he often shared with friends sarcastic anecdotes about his experiences living under communism. Professor Dvorak will forever live in our memory.