The Austrian IFToMM community mourns the loss of its longtime chairman o. Univ. Prof. Dr.-Ing. Karl Wohlhart, emeritus professor of Mechanics at the Technical University in Graz, Austria who passed away on July 21, 2023.

Karl Wohlhart was born on September 11, 1928 in Aschach an der Steyer in Upper Austria. In 1942 he entered the newly established higher engineering school in Steyr. Already two years later in autumn 1944 teaching at this school was stopped,  teachers and pupils had to work in the military part of the Steyr company to work on development and production of weapons for the second world war. But soon he was enlisted to RAD (Reichsarbeitsdienst), got a weapon from the first world war and was charged, together with other 16-year-olds, to defend the Phyrn pass and became American war prisoner. He was released in summer 1945 from prison.

In autumn 1945 he could return to the higher engineering school which he finished in summer 1947 with distinction. Later in 1947 he started to study mechanical engineering at the Technical University in Graz. He finished the first part of this study (erste Staatsprüfung) successfully in such a short time that the famous and feared professor of mechanics, Karl Federhofer, offered him a teaching assistant position. Having now some own money he almost completely abandoned his engineering studies, visited lectures at the Karl Franzens University in many different fields, learned languages, played the violin and went for summer internships to England and France. After several years, mainly because his family grew and more money was necessary, he resumed his mechanical engineering studies and finished in 1961 with distinction. He became assistant professor at TU Graz, worked on his doctoral thesis with the title “Über die Verwendung der kinematischen Pläne zur Ermittlung der Eigenfrequenzen einer Getriebekette” (Using kinematic polar vector diagrams for the determination of natural frequencies of planar constrained kinematic chains). He finished his doctoral studies in 1966 with distinction. One of the reviewers of the thesis acclaimed it as the shortest and most substantial since several years.

After a few years, now already 40 years old, he decided to leave university and work with the DFVLR (Deutsche Forschungsanstalt für Luft und Raumfahrt, today DLR) on topics like dynamics of aircraft wings and flexible rod rockets. Results of this research are published in journals like ZAMM, ZAMP and ZFW. Because of this successful work he could apply 1971 for Habilitation at the Ruhruniversität Bochum with the thesis “Schwingungen von Seilen” (vibrations of cables). After having obtained Habilitation he gave lectures on “Nonlinear Vibrations” in Bochum and was invited to give lectures at full professorship appointment procedures in Aachen, Braunschweig, Leoben, Innsbruck and Graz. He succeeded in Graz and was appointed in 1972 as full professor for “Theoretische Maschinenlehre”. In 1974 his institute was merged with the institute of Mechanics and in 1977 he became full professor of Mechanics and head of the institute of Mechanics. Since 1997 he has been emeritus professor, never stopping his daily scientific research.

Karl Wohlhart has published more than 70 papers, most of them single authored, on many different aspects of mechanics, but with a focus on mechanisms. Over many years he was working on different polyhedral linkages, coined the notion “kinematotropic linkage” for linkages which change the degree of mobility and invented at the age of 90 a new type of semi-regular polyhedra, which is an exceptional result when considering that research on polyhedra is more than 2000 years old! Furthermore, he worked during his whole teaching life on lecture notes for the many different lectures he joyfully taught. Two of these lecture notes transferred into books on “Basics of Statics and Dynamics”.

For 12 years Karl Wohlhart was chairman of IFToMM Austria and in the period 1995-1999 he was member of the EC of IFToMM. He got several prestigious awards, such as the “Großes Goldenes Ehrenzeichen des Landes Steiermark” or  “Österreichisches Ehrenkreuz für Wissenschaft und Kunst I. Klasse“.

With Karl Wohlhart the IFToMM community lost an incredible humble, hardworking, multifaceted and productive researcher who has been a role model for generations of students and researchers.

Contributed with deep appreciation by Prof. Manfred Husty.