This Speciai Issue of Journal of Vibration and Control, is dedicated to Professor Friedrich G. Pfeiffer on the occasion of his 65th birthday and his retirement from teaching activities at the Mechanical Engineering Faculty of the Munich Technical University. Several colleagues, who hold Professor Pfeiffer in esteem for bis scholarly activities and share common scientific interests and friendship, agreed to contribute to this work.
Friedrich G. Pfeiffer was born in Wiesbaden, Gennany on February 22, 1935. He obtained a Dipl.-Ing. in mechanical engineenng from TH-Darmstadt in 1961 and a Dr.-Ing. in aerodynamics from the Institut für Flugtechnik, TH-Darmstadt,. with summa cum laude in 1965. In 1966, he joined the Space Dynamics Division of Bolkow GmbH, Ottobrunn as an Engineer, and, in 1970, he was appointed Head of the Department of Applied Mechanics in Space. He also has industrial experience. He served as a Technical Manager of Bayernchemie GmbH and Member of the Board of the Guided Missile Division of Messerchmitt-Bolkow-Blohm (MBB), where he was responsible for research and development. In 1982, he joined the Faculty of Mechanical Engineenng of the TU-Munich as full professor of mechanics and successor to Professor Magnus. He continued in this position until his formal retirement from teaching in 2000. He has served as Vice-Dean of the Faculty of Mechanical Engineering (1992-95 and 1995-96) and Dean and Member of the Senate of the TU-Munich (1995-96). He has served as consultant to many automotive and mechanical engineering firms, including BMW, OPEL, AUDI, Volkswagen, DASA, Voith; BHS, MAN, and various smaller companies. He has served as a member of the Senate of the Nationai Research Foundation (Deutsche Forschungsgemeinschaft (DFG)), a member of the DFG Committee of Applied Research, and President of Gesellschaft fur Angewandte Mathematik und Mechanik (GAMM) (2002-2005).
He has organized several conferences, including
EUROMECH Colloquium 268 on “Dynamics and Control of Flexible Structures”, Munich, September 11-14, 1990;
lst European Solid Mechanics Conference (lst ESMC), Munich, September 9-13, 1991;
IFAC Motion Control, Munich, October 9-11, 1995;
GAMM Tagung, Regensburg, March 24-27, 1997;
EUROMECH Colloquium on “Biology and Technology of Walking”, Mumch, March 23-25, 1998;
IUTAM Symposium on “Unilateral Multibody Dynamics”, Munich, August 3-7, 1998;
Geometric and Multibody Mechanics: Nonlinear Dynamics and Control, Oberwolfach, July 25-30, 1999.
He has given a large number of invited Iectures and was frequently a plenary and keynote lecturer.
He is a member of many professional societies:
VDI (Verein Deutscher Ingenieure);
GAMM (President);
DGLR (Deutsche Gesellschaft fur Luft- und Raumfahrtl), Deutscher Hochschulverband;
EUROMECH (European Society of Mechanics, former member of the council), and former chairman of the standing committee of ENOC (European Nonlinear Oscillations Conference);
IEEE (The Institute of Electrical and Electronics Engineers, Senior Member, USA); and ASME (American Society of Mechanicai Engineers).
He has served as editor, associate editor, and member of the editorial board of many scientific journals:
Editor-in-Chief of Archive of Applied Mechanics, Springer-Verlag (since 1996);
Associate Editor of Ingenieur-Archiv (until 1996);
Editorial Board of Nonlinear Dynamics (since 1989);
Editorial Board of Machine Vibration (1990-95);
Editorial Board of Chaos (1990-95);
Editorial Board of European JoumaI of Solid Mechanics (1993-2000);
Editorial Board of Autonomous Robots (1993-97);
Editorial Board of Journal of Vibration and Control (since 1995);
Editorial Board of Intelligent Control and Systems (since 1996);
Editorial Board of the Royal Society, A-Side (since 1998).
He has received several awards, which include:
Bordoni Prize, 1990, Rome (IFLP);
Senior Member IEEE, 1991;
Korber Prize for European Science, 1993;
Honorary Doctor (Dr. h.c.) of the Russian Academy of Sciences, 1998;
Consulting Professor Tongji, University of Shangai, 1999;
Order of Merit FRG (Bundesverdienstkreuz), 2000.
He has published more than 200 papers, five books, and several book chapters; a selected list of his publications is given at the end of this Preface.
Professor Pfeiffer has established himself as an authority in various specialties of mechanical engineering. Most of his research has been devoted to the general area of multibody dynamics: theoretical aspects and engineering applications. He has made fundamental contributions to multibody mechanics.
His Ph.D. Dissertation dealt with wind-tunnel design; he introduced a method to calculate the interference of open and closed wind tunnels with the floor. He has also studied the mechanical behavior of gyros containing liquid and he has investigated the coupling between the mutational oscillation of the gyro and the natural oscillation of the liquid.
Many of Professor Pfeiffer’s papers are concerned with the planning and optimization of robotic motions. He has treated extensively issues of path planning and obstacle avoidance of free trajectories when the manipulator intentionally has contact with its environment. He has proposed an algorithm for finding the time-optimal trajectory for a fully actuated manipulator along a specified path. He has also introduced a method for the planning of a robotic assembly by numerical optimization of the position and joint controller coefficients.
Professor Pfeiffer has developed a uniform theory for the analysis of multibody systems with unilateral contacts. His contributions in this area cover several theoretical and practical aspects, including phenomena such as impacts, stick-slip, and time-variant kinematical loops, which generate unsteady motions. Each of these unilateral phenomena by itself leads to more complexity in the analysis of the motion: the situation is even more involved in multiple contacts of a multibody configuration. He has dealt with all these challenges by defining the complementary properties of contact dynamics and by the application of complementary algorithms. He has considered the time-variant structure of such mechanical systems, the state-dependent change of the constraint combinations, and the equations of motion by special analytical and numerical procedures. He also has paid attention to relevant mathematical aspects, such as linear complementary problems for plane contacts and their extension to two-dimensional dynamical contact cases with dependent unilateral constraints and impacts with friction.
Professor Pfeiffer has analyzed in depth the important problem of impulsive vibrations in machines, where multiple unilateral contacts occur. Typical examples include the rattling phenomenon in gearboxes, drive trains of automobiles, and geared drives of diesel engines. Based on an impulsive theory for multibody systems, he has presented a number of innovative procedures (patching methods, point mapping approaches, stochastic modeling) to analyze the rattling vibrations exhibited by these kinds of systems. He has shown that vibrations are chaotic, and hence he has analyzed them by introducing a discrete stochastic model described by a mean map. This map is, by itself, significant for chaos study.
Professor Pfeiffer has covered other topics, which include self-excited friction oscillators, multiple impact with friction, and nonlinear dynamics of stick—slip systems. These are connected to practical applications and measurements (e.g., dampers for gas-turbine blades, dynamics of a railroad vehicle, couplings in machines exhibiting backlash, and friction phenomena). He has thoroughly studied even these problems in the framework of a common theoretical approach by presenting and discussing several formulations along with their solution methods.
Finally, we would like to thank all the colleagues who have contributed to this issue and we wish Professor Pfeiffer a long and productive research activity.
Fabrizio Vestroni and Ali H. Nayfeh