Prof. Dr.Ing. habil. Willi Rehwald – 90 Years - IFToMM

Prof. Dr.­Ing. habil. Willi Rehwald – 90 Years
Laudatio
Willi Rehwald was born on December 14, 1917 in the town Kroppenstedt in Sachsen­
Anhalt/Germany. He had his pre­college schooling and Abitur in 1936 at Oberrealschule in the city of
Egeln, and then was active as a practicant at the Junkers­Aircraft­Company for nearly one year. He
served the compulsory military training and National Defence services for the next three years.
Interested in aeronautics, he specialised in this field at Technical University of Berlin­Charlottenburg
during 1941­42. This made him a good aircraft engineer and later as executive chief engineer of an
aircraft warp.
After the 2nd world war he also underwent training in coal mining, conveying equipment, building
machines, and logistics by Braunschweigische Kohlenbergwerke in Helmstedt, during 1945­47. The
following years Willi Rehwald studied at Technical University Braunschweig, at the faculty
mechanical engineering, speciality machine­tools and took his Diplom­Ingienieur degree in 1949 from
TU Braunschweig. Immediately he changed to industry, where he became the chief R&D at the Calor­
Emag GmbH Duesseldorf. From 1951­55, he served as Assistant Professor at the Institute for Applied
Mechanics at TU Braunschweig.
Later Willi Rehwald was a Dozent / Baurat during 1955­59 at Ingenieurschule Essen, teaching
mathematics, mechanics, control and mechanisms theory. He also served as chief and advisory
engineer of IBM Germany in Stuttgart / Sindelfingen for a period of 15 years up to 1974, and was very
engaged in creating mechanical basic­groups for computer technique, e.g. for quick transportation,
reading and control of punched cards. During this period, he took his Dr.­Ing. degree in 1962 in
Linkage Mechanics by the topic “Kinematik und Kinetik der Viergelenkgetriebe in analytischer
Darstellung” at TU Braunschweig. This is the base for his next work, creating software for kinematics
and kinetics of mechanisms theory, a very important tool for application on the IBM computers in
industry. It was the starting point of the computer programme “KOSIM ­ Computer Aided Simulation
of Mechanisms”. From this time it has been improved step by step. In the 80 and 90 decades the
KOSIM software was adapted to laptops, which appeared at the market. The printing of diagrams,
hodographs and animation of linkages has been added in such an elegant way, that it became attractive
more and more. In this time the computer programme KOSIM has been improved on the basis of
many solved problems on linkage analysis and by defining several basic tasks. Now it is a universal
programme, because it can analyse any types of linkages with respect to position­geometrical, to
differential­geometrical and to mass­geometrical attributes as well as to the motion­behaviour of
linkages, considering several motion­conditions. The current version realizes the MMD / MEN­
MACHINE­DIALOGUE with respect to:
· Linkage Type­Dialogue,
· Position­Parameter­Data­Dialogue,
· Task­Dialogue by: animation of linkages, position geometrical and differential­geometrical tasks,
mass­geometrical and force­geometrical tasks, kinetical and kinematical tasks,

· Dialogue for Data­output, etc.
After the task­dialogue follows the calculation, which is very quick. According to the current task, the
KOSIM­programme produces hodographs of all vector­variables and diagrams of all scalar­variables.
The hodographs and diagrams appear on the screen and can be printed. It is also possible to print
coupler curves including its geometrical transfer­functions of 1 st and 2 nd order, also geometrical
polodes of 1 st and 2 nd order.
Prof. Willi Rehwald has significantly contributed to the modern background­knowledge about analysis
and computation of linkage mechanics. For three years he lectured on “Numerical methods in
mechanism theory” at TU Darmstadt (1965­68). He taught the same subject as Dr.­Ing. habil. and apl.
Professor at University of Karlsruhe from 1964 to 1983.
In recognizing his fundamental scientific work during the last decades he received several honours
such as Honorary Academic of the Engineering Academy of the Republic of Kazakhstan in 1997 and
Honorary Member of IFToMM Technical Committee on Linkages and Cam Mechanisms in 2002.
Prof. Rehwald has published several books and research papers to his credit; a special selection is
listed in the appendix. He is the author of the book KOSIM – Computer Aided Linkage Simulation
(see appendix), jointly with Prof. Kurt Luck. Realising the need for software useful in the simulation
and dynamic analysis of mechanisms, Prof. Rehwald developed and created the universal computer
programme KOSIM, with which everybody can solve nearly all problems of linkage mechanics.
Prof. Dr.­Ing. habil. Dr. h.c. Kurt Luck
IFToMM TC Linkages and Cams, Honorary Member
Appendix:
1) Dissertation: Kinematik und Kinetik der Viergelenkgetriebe in analytischer Darstellung.
VDI­Forschungsheft 503, VDI­Verlag Duesseldorf 1964
2) Habilitation: Analytische Kinematik von Koppelebenen. Otto Krausskopf­Verlag GmbH,
Mainz 1972
3) KOSIM – Koppelgetriebesimulation, Fortschritt­Berichte VDI, Reihe 1, Konstruktionstechnik/Maschinenelemente,
Nr. 332, VDI Verlag GmbH, Duesseldorf 2000
4) KOSIM – Computer Aided Linkage Simulation, English­version of 3), published by
Vellore Institute of Technology, Deemed University, International Relations­Office,
Vellore ­ 632 014, Tamil Nadu, India, 2006
5) Linkage Type Identification and Synthesis through Elementary Groups. Proceedings of the
IX IFToMM World Congress on TMM, Volume 1, pp.193­196, Milano, August 1995
6) Phaenomene der Koppelgetriebe­Mechanik. Proceedings of SYROM 1997, Volume 4,
pp.127­132, Bucharest, August 1997.