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TUL - Division of Dynamics

Dane Kontaktowe / Contact Data



2016-09-09

Seminar by Professor Stefano Lenci from Ancona

Professor Stefano Lenci from Universita Politecnica delle Marche, Ancona, Italy gave excellent seminar entitled: Dynamical Integrity: a step after stability.

Professor Stefano Lenci from Universita Politecnica delle Marche, Ancona, Italy gave excellent seminar entitled: Dynamical Integrity: a step after stability at Sept 9, 2016.

Abstract: The achievements occurred in nonlinear dynamics over the last thirty years entail a substantial change of perspective when dealing with vibration problems, since they are now deemed ready to meaningfully affect the analysis, control and design of mechanical and structural systems. This talk aims at overviewing the matter, by highlighting and discussing the important, yet still overlooked, role that some relevant concepts and tools may play in engineering applications. Upon dwelling on such topical concepts as local and global dynamics, bifurcation and complexity, theoretical and practical stability, attractor robustness, basin erosion, dynamical integrity, recent results obtained for a variety of systems and models of interest in applied mechanics and structural dynamics are overviewed in terms of analysis of nonlinear phenomena and their control. This is discussed for discrete systems and reduced order models of continuous systems, for applications ranging from macro- to micro/nano-mechanics.


2016-09-08

Two successful defenses of PhD theses in the Division

Mr Piotr Brzeski and Mr Krzysztof Jankowski have successfully defended their PhD theses today. Piotr work was entitled: Energy transfers in systems of coupled oscillators and the Krzysztof one: Modelling friction for the analysis of different dynamical systems. Both theses written and defended in English in brilliant way finished their Authors' first step into scientific career. Congratulations!


2016-05-24

Our PhD student Piotr Brzeski granted with START scholarschip

The Foundation emerged winners of the twenty-fourth edition of the scholarship program START. Among the grantees is a young researcher from the Department of Mechanical Engineering, MSc. Piotr Brzeski from the Division of Dynamics. This is his second awarded START scholarship. In addition to the scholarship he was also awarded a grant for a study trip to the group of Professor Lawrence N. Virgin at Duke University, USA. Mr Brzeski is the fourth year PhD student in mechanics. His supervisor is Dr. Przemysław Perlikowski, prof. TUL, also two-time winner of the START scholarship from the FNP. In the competition participated 1291 candidates selected 121 most talented young scientists who received FPS annual stypendium. The ceremony of awarding diplomas was held on May 21 at the Royal Castle in Warsaw. The relationship of this event can be seen on the channel of the Foundation for Polish Science on YouTube: https://www.youtube.com/watch?v=z3K3CrbNB0c


2016-01-14

MME updated - May 2017

See Journal subpage: MME


MME updated - March 2017

See Journal subpage: MME


MME updated - January 2017

See Journal subpage: MME


MME updated - September 2016

New articles has been added to our Journal, April - Mechanics and Mechanical Engineering. See Journal subpage: MME

MME updated - June 2016

New articles has been added to our Journal, April - Mechanics and Mechanical Engineering. See Journal subpage: MME

MME updated - May 2016

New articles has been added to our Journal, April - Mechanics and Mechanical Engineering. See Journal subpage: MME


MME updated - March 2016

New articles has been added to our Journal, March - Mechanics and Mechanical Engineering. See Journal subpage: MME


Seminar by Patrycja Jaros

We invite all to the seminar by Patrycja Jaros: Solitary states in Kuramoto model with inertia (20 mins) which will be held in 2M221 at Friday, January 29, 2016, 10:00.


Seminar by Prof. Marian Wiercigroch

We warmly invite everyone to the seminar by Prof. Marian Wiercigroch from University of Aberdeen: Grazing Induced Bifurcations: Innocent or Dangerous? which will be held in 2M221 at January 26, 2016, 12:15.

Professor Wiercigroch comes from Centre for Applied Dynamics Research, School of Engineering, University of Aberdeen, UK. His abstract follows:

In this lecture I will examine nature of subtle phenomenon such grazing bifurcations occurring in non-smooth systems. I will start with linear oscillators undergoing impacts with secondary elastic supports, which have been studied experimentally and analytically for near-grazing conditions [1]. We discovered a narrow band of chaos close to the grazing condition and this phenomenon was observed experimentally for a range of system parameters. Through stability analysis, we argue that this abrupt onset to chaos is caused by a dangerous bifurcation in which two unstable period-3 orbits, created at "invisible" grazing collide [2].

The experimentally observed bifurcations are explained theoretically using mapping solutions between locally smooth subspaces. Smooth as well as non-smooth bifurcations are observed, and the resulting bifurcations are often as an interplay between them. In order to understand the observed bifurcation scenarios, a global analysis has been undertaken to investigate the influence of stable and unstable orbits which are born in distant bifurcations but become important at the near-grazing conditions [3]. A good degree of correspondence between the experiment and theory fully justifies the adopted modelling approach.

Similar phenomena were observed for a rotor system with bearing clearances, which was analysed numerically [4] and experimentally [5]. To gain further insight into the system dynamics we have used a path following method to unveil complex bifurcation structures often featuring dangerous co-existing attractors.

References:
1. Ing, J., Pavlovskaia, E.E., Wiercigroch, M. and Banerjee, S. 2008 Philosophical Transactions of the Royal Society – Part A 366, 679-704. Experimental study of impact oscillator with one sided elastic constraint.
2. Banerjee, S., Ing, J., Pavlovskaia, E., Wiercigroch, M. and Reddy, R. 2009 Physical Review E 79, 037201. Invisible grazing and dangerous bifurcations in impacting systems.
3. Ing, J., Pavlovskaia, E., Wiercigroch, M. and Banerjee, S. 2010 International Journal of Bifurcation and Chaos 20(11), 3801-3817. Complex dynamics of bilinear oscillator close to grazing.
4. Páez Chávez, J. and Wiercigroch, M. 2013 Communications in Nonlinear Science and Numerical Simulation 18, 2571–2580. Bifurcation analysis of periodic orbits of a non-smooth Jeffcott rotor model.
5. Páez Chávez, J., Vaziri Hamaneh, V. and Wiercigroch, M. 2015 Journal of Sound and Vibration 334, 86-97. Modelling and experimental verification of an asymmetric Jeffcott rotor with radial clearance.



MME updated - December 2015

New articles has been added to our Journal, December - Mechanics and Mechanical Engneering. See the Articles subpage: MME


Katedra Dynamiki Maszyn - Division of Dynamics

90-924 Łódź, ul. Stefanowskiego 1/15
K-13, bud. A22
Poland
tel.: +48 42 631 2231; +48 42 631 2430
Fax: +48 42 631 2702
e-mail: k-13@adm.p.lodz.pl;  tomaszka@p.lodz.pl










Entry date: 2015-07-24
Modified: 2017-06-22
Entered by: J Wojewoda