D. ROGER J. OWEN (1942-2020)

BY HYWEL THOMAS AND CHENFENG LI
SUBMITTED BY THE NAE HOME SECRETARY

DAVID ROGER JONES OWEN was born on May 27, 1942, near the small town of Llanelli in South Wales. His parents were Evan William and Margaret Owen, and he had one sister, Rita, who was four years his senior. His father was mathematically gifted but left school at age 12 to work in the family business. His mother, as was typical at the time, managed the household and also supported the family business. His maternal grandmother, who spoke only Welsh, lived with them. The family spoke Welsh at home, and throughout his life, conversations with his sister and cousins inevitably reverted to it.

Roger’s early education began at the local primary school, where the headmaster, Major Isaac Thomas, instilled in him a strong foundation in values and discipline. He was one of the first people to have a lasting influence on Roger’s life. At age 10, he passed the Eleven Plus examination and entered Llanelli Boys Grammar School in 1953.

Like all grammar schools of the time, the curriculum was broad, with a balance of arts and sciences. His interest in mathematics was sparked by his teacher, J.V. Harries, who nurtured his talent for applied mathematics. This influence likely led Roger to pursue engineering at university.

He earned a civil engineering degree from the University of Wales Swansea. Studying at Swansea proved to be an inspired choice. During his second year, a new head of department arrived, O.C. (Olek) Zienkiewicz (NAE 1981), who would go on to become one of the leading figures in the field of finite elements.

Roger completed his undergraduate degree in civil engineering in 1963, followed by a master’s degree in 1964. During his final year, he expressed interest in studying abroad, and Zienkiewicz arranged for him to pursue a Ph.D. at Northwestern University in Evanston, Illinois. Zienkiewicz had previously served as a professor of structural engineering at Northwestern before joining Swansea. Roger completed his Ph.D. in 1967 and went on to serve as a Walter P. Murphy Research Fellow at Northwestern.

In 1968, Zienkiewicz persuaded him to return to Swansea as a research fellow. There, Roger was rapidly introduced to the finite element method and became captivated by its research potential. He remained at Swansea for the rest of his career, advancing through the academic ranks of lecturer, senior lecturer, reader, and professor. When he reached the then-mandatory retirement age of 67 in 2009, he accepted a part-time appointment as a research professor, a position he held until his passing in January 2020.

Roger’s doctoral work at Northwestern, under the guidance of Toshio Mura (NAE 1986), focused on theoretical and applied mechanics. His research, and subsequent work as a postdoctoral fellow, explored the analytical modeling of nonlinear material deformation. By leveraging the relationship between dislocation density and eigenstrain distributions, he developed mechanisms based on continuously distributed dislocations to reproduce macroscopic elasto-plastic material deformation.

Upon his return to Swansea, he developed a profound interest in computational methods, marking the beginning of a transformative influence on the field. He went on to play a seminal role in shaping computational strategies for nonlinear problems, advancing both fundamental materials studies and practical engineering applications. His contributions were both systematic and groundbreaking, laying the foundation for new paradigms in computational mechanics. Initially focused on the plastic deformation of materials, his research rapidly evolved to address increasingly complex phenomena, including friction, contact mechanics, fracture dynamics, and uncertainty quantification, pioneering approaches that continue to shape the field today.

His early work involved developing finite element methods for solving small-strain elasto-plastic problems. He was the first to unify the theoretical and computational aspects of elasto-plastic material deformation, offering comprehensive solution strategies for practical problems in plasticity. He further expanded the field by introducing anisotropic effects into the computational modeling of elasto-plastic plates and shells, including pioneering studies on laminated plates and shells. These contributions — achieved despite the severe computing limitations of the time — enabled accurate and reliable computational solutions that were previously out of reach. Collectively, his work laid the foundation for modern computational mechanics and influenced generations of researchers and practitioners.

In the late 1980s and 1990s, Roger’s research advanced the computational treatment of elasto-plastic problems involving finite strains, marking a pivotal shift in the field. During this time, the importance of consistent linearization in return-mapping schemes became clear, and the deformation kinematics of finitely straining solids were significantly refined. A groundbreaking contribution was the introduction of logarithmic strain as the fundamental measure of deformation, which, combined with the concept of the exponential map for integrating rate equations, established a robust and mathematically sound computational framework for modeling plastically deforming materials under finite strain conditions.

Practical problems involving finitely deforming elasto-plastic solids almost always include complex frictional contact conditions. These interactions introduce substantial nonlinearities, making their computational simulation especially challenging. A breakthrough came with the development of a consistent tangent model featuring a local quadratic rate of convergence, which dramatically improved the computational efficiency and accuracy of such simulations. To enhance the modeling of material failure, Roger incorporated damage models into the finite strain elasto-plastic framework. One key innovation was the introduction of an additive split in the principal stress space, enabling the differentiation between damage evolution under tension and compression regimes. He also made influential contributions to nonlinear computational mechanics, including the modeling of strain localization phenomena in both classical and Cosserat continua. These developments laid the foundation for more advanced computational approaches to studying material behavior under extreme conditions.

A natural extension of finite strain modeling is the need for adaptive mesh refinement to accommodate the gross geometric deformations inherent in such problems. Recognizing this challenge, Roger’s group made contributions to the development of advanced computational strategies for nonlinear problems under both static and dynamic conditions. Their work introduced robust methodologies for seamlessly mapping a consistent set of variables between successive meshes in elasto-plastic simulations. At the time, these advancements represented a major leap forward in computational mechanics, laying the groundwork for modern adaptive techniques in large-deformation analysis.

Over the past three decades, Roger was at the forefront of developing computational methods for high-performance simulation. His early work on shared memory machines laid the foundation for later breakthroughs in parallel processing strategies, especially on distributed memory platforms. Among his key achievements was the development of dynamic domain partitioning schemes and incremental inter-processor data migration techniques — crucial innovations for problems involving multifracturing solids or adaptive mesh refinement, where continuously evolving mesh topology requires real-time computational adaptability.

Over the last decade of his life, Roger focused on the development of discrete element methods for particulate modeling and the simulation of multifracturing phenomena in materials, pioneering key advancements in the field. His work significantly extended continuum modeling approaches for finitely deforming solids by incorporating damage- and fracture-based failure mechanisms. One of his most notable innovations was the introduction of localized material separation, enabling a seamless transition from a continuous solid to a multifractured particulate state. This methodology addressed several critical challenges, including modeling incipient fracture on a continuum basis, developing procedures for inserting discrete fractures, ensuring accurate mapping of solution variables between continuous and discontinuous states, and preserving energy and momentum throughout the transition.

In his later years, Roger turned his attention to stochastic finite element modeling, developing advanced techniques to describe random media fields. This work has been vital for accounting for uncertainties in the distribution of material properties and internal fractures in geological formations and other solids. By integrating probabilistic approaches into computational mechanics, this research enhanced the predictive accuracy and robustness of simulations for real-world applications. A key collaborator in this work was his former Ph.D. student, Chenfeng Li, now director of the Zienkiewicz Institute for Modeling, Data and AI at Swansea University.

Roger’s research fostered extensive international collaborations that helped shape the global computational mechanics community. His work connected him with many of the field’s leading figures, including Thomas J.R. Hughes (NAE 1995), Ted Belytschko (NAE 1992), Robert L. Taylor (NAE 1991), J. Tinsley Oden (NAE 1988), and Klaus-Jurgen Bathe in the U.S., as well as Mike Crisfield, Eugenio Onate, Peter Wriggers, Herbert Mang (NAE 2004), Bernhard Schrefler, Pierre Ladeveze, Ekkehard Ramm (NAE 2008), and Erwin Stein in Europe.

Over the course of his career, he authored seven textbooks and more than 400 publications and delivered over 100 keynote and plenary lectures at major international conferences in computational mechanics. He was the founding editor of Engineering Computations and edited 30 additional monographs and conference proceedings. He supervised approximately 70 Ph.D. students, many of whom have gone on to become prominent researchers in academia and industry around the world, with many of them maintaining close friendships with him throughout his life.

Recognizing the industrial potential of finite element methods, he founded Rockfield Software Ltd, transforming it into an internationally recognized engineering analysis company. Serving clients across oil and gas, mining, defense, and manufacturing sectors, Rockfield became a hub for high-tech innovation, with 75 percent of its workforce holding Ph.D degrees. Under Roger’s leadership, the company received two Queen’s Awards for Innovation, thanks to pioneering advancements in structural retrofitting and multi-fracturing simulations for critical industries.

Roger met his wife, Janet Pugh, while still at school. Together, they built a family, raising two daughters — Kathryn, born in 1967, and Lisa, in 1970 — and later welcoming a granddaughter, Bethan, born to Lisa in 2002.

From an early age, Roger had an intense passion for rugby football. He played for over 15 years at a highly competitive Welsh level — marked by lost teeth and broken bones. He played alongside and against several international players, though he humbly admitted he never reached their caliber. When aches and pains eventually made it too painful to rise from bed, Roger retired from rugby, leaving a significant void in his sporting life. He later took up tennis, which he embraced as a new challenge, and eventually transitioned to golf. He also played cricket for over 25 years with the Swansea University Staff team, serving as an all-rounder, and was regularly featured among the top performers in both batting and bowling averages.

Upon reaching the milestone of age 40, he decided to take up flying — a pursuit he embraced with characteristic enthusiasm. He went on to earn a private pilot’s license, along with instrument and night rating certifications. Soon after, he became co-owner of a Cessna 172 Skyhawk (G-AVVC) and spent the next two decades flying across the United Kingdom. His time in the skies came to an end in 1999, following a quadruple heart bypass operation.

Roger’s contributions were recognized with numerous awards and honors throughout his career. He was elected Fellow of the Royal Academy of Engineering in 1996 and awarded an Honorary D.Sc. by the University of Porto, Portugal, in 1998. In 2002, he received the Computational Mechanics Award from the International Association for Computational Mechanics (IACM) for “outstanding contributions in the field of computational mechanics.” The following year, he was awarded the Warner T. Koiter Medal by the American Society of Mechanical Engineers (ASME) for “contributions to the field of theoretical and computational solid mechanics.” In 2004, he received IACM’s highest honor, the Gauss-Newton Medal. He was elected Fellow of the Royal Society in 2009 and became a Founding Fellow of the Learned Society of Wales in 2010. In recognition of his global impact, he was elected Foreign Member of both the United States National Academy of Engineering (NAE) and the Chinese Academy of Sciences (CAS) in 2011. His longstanding contributions to international collaboration were further recognized with the China Friendship Medal in 2016.

Acknowledgments

We are hugely indebted to Kathryn Owen, Roger’s daughter, for all her help collecting the information about Roger’s early years.