Abstract: Hysteresis is a highly nonlinear phenomenon occurring in many
disciplines involving system that possess memory, including inelasticity,
electricity, magnetism etc. A wide variety of shapes of hysteretic loops can
be portrayed by Bouc-Wen differential model. Usually, the mechanical
hysteretic loops are obtained experimentally by imposing cyclic relative
motion between the mounting ends on the testing rig of a material sample,
structural element or vibration isolator and by recording the evolution of
the developed force versus the imposed displacement. Due to the symmetry of
Bouc-Wen differential equation with respect to the displacement input, the
standard version of this model cannot be applied to describe asymmetric
hysteretic loops. The asymmetry of experimental hysteretic curves is due to
the asymmetry of the mechanical properties of the tested element, of the
imposed cyclic motion, or of both factors. In this paper, the asymmetric
hysteretic characteristics are modeled by matching the solutions of two
different Bouc-Wen equations, corresponding to negative and positive values
of the imposed cyclic displacement or by employing a modified Bouc-Wen
model. The efficiency of the proposed approach is illustrated by its
application to portraying the asymmetric hysteretic behavior of two
vibration control devices.
Brief Biography of the Speaker:
Dr.Tudor Sireteanu is the director of the Institute of Solid Mechanics of
the Romanian Academy since 1990. He was born in 1943 in Bucharest. He is a
graduate of the University of Bucharest, Faculty of Mathematics and
Mechanics and has been with the Institute of Solid Mechanics since
graduation, working in the field of vibration control. In 1971 he received a
Fulbright Grant for a research stage at California Institute of Technology,
Department of Engineering. In 1982, he received his PhD degree in applied
mathematics from the University of Bucharest, Faculty of Mathematics and
Mechanics with a thesis on nonlinear random vibrations. Since 1992 he is PhD
advisor in the field of applied mathematics and associated professor with
the University Politechnica Bucharest since 1997. His scientific work is
focused on applied vibration theory, experimental methods and signal
processing, the application of novel techniques such as semi-active control
strategies assisted by computational intelligence methods( genetic
algorithms, fuzzy logic and neural networks). Dr.Tudor Sireteanu was awarded
the Romanian Academy Prize “Traian Vuia” (1998) for a series of papers
published in the field of dynamic system control. In 2004 dr. Tudor
Sireteanu received the title of Honorific Member of the Academy of Technical
Sciences from Romania in recognition of his major contribution to the
development of vibration control applied to automotive suspensions,
machinery vibration isolation and building seismic protection. He has
published more than 100 scientific papers in scientific journals and
international conference proceedings and three books on automobile
suspensions, magneto¬-rheological dampers and semi-active control. Dr.Tudor
Sireteanu is the editor scientific secretary of the “Revue Romaine de
Mécanique Appliquée”, published by the Printing House of the Romanian
Academy.
