Plenary Lecture
Modeling of Vibrations of Lumped and Continual
Mechanical Systems by Ordinary Differential Equations
Professor Jan Awrejcewicz
Technical University of Lodz
Department of Automation and Biomechanics
Lodz, Poland
E-mail:
awrejcew@p.lodz.pl
Abstract:
Example taken from mechanical engineering, i.e. dynamics
of a triple physical pendulum exhibiting a plane motion
(lumped system) and dynamics of a cylindrical shell with
the circular cross section (continual system ) are
studied. In the first case the Lagrange’a equations are
used to derive the governing second order ODEs, whereas
in the second case strongly nonlinear PDEs are reduced
to a truncated set of ODEs via FDM (Finite Difference
Method) and the higher order Bubnov-Galerkin
approximations.
Mathematical modeling of triple pendulum includes
details, taking into account some characteristic
features (for example, real characteristics of joints
built by the use of roller bearings) as well as some
imperfections (asymmetry of the forcing) of the real
system. Parameters of the model are obtained by a
combination of the estimation from experimental data and
direct measurements of the system's geometric and
physical parameters. A few versions of the model of
resistance in the joints are tested in the
identification process. Good agreement between both
numerical simulation results and experimental
measurements have been obtained and presented. Some
novel features of our real system chaotic dynamics have
been reported.
In the case of the circular cylindrical shell dynamics
the problems related to its regular, bifurcational and
chaotic dynamics are illustrated and discussed, as well
as it’s local (global) stability loss versus control
parameters. In addition, the convergence and validity of
the applied numerical algorithms are studied.
The lecture includes movies and animations of regular
and chaotic dynamics of the analysed systems.
Brief Biography of the Speaker:
Jan AWREJCEWICZ received the M.Sc. and Ph.D. degrees in
the field of Mechanics from the Technical University of
Lodz in 1977 and 1981, respectively. He received also
his bachelor's degree in Philosophy in 1978 from the
University of Lodz, and DSc. degree in Mechanics from
the Technical University of Lodz in 1990. He is an
author or co-author of abort 500 publications in
scientific journals and conference proceedings,
monographs (37), text books (2), edited volumes (3),
conference proceedings (11), journal special issues
(11), other books (8) and other short communications and
unpublished reports (225). He is now the Head of
Department of Automatics and Biomechanics, and the Head
of Ph.D. School on 'Mechanics' associated with the
Faculty of Mechanical Engineering of the Technical
University of Lodz. In 1994 he earned the title of
Professor from the President of Poland, Lech Walesa, and
in 1996 he obtained the golden cross of merit from the
next President of Poland, Aleksander Kwasniewski. He is
a contributor to 50 different research journals and to
150 conferences. During his scientific travel he visited
60 different countries. His papers and research cover
various disciplines of mathematics, mechanics,
biomechanics, automatics, physics and computer oriented
science (more details at www.abm.p.lodz.pl).
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