Plenary Lecture

Advances on Characteristics Changing and Working State Degrading of Passive Vibroisolation Elements

Dr. Silviu Nastac
Research Center for Mechanics of Machines and Technological Equipments
University "Dunarea de Jos" of Galati
Calea Calarasilor 29, 810017, Braila

Abstract: This paper presents some special aspects regarding changing and degrading phenomenon of theoretical characteristics for vibroisolation elements during the exploitation. The approaches are based on the internal thermodynamic phenomenon developed into the rubber elements subjected with the various and intensive dynamic charges. The influences are involved about both the static and dynamic characteristics, and consist of rigidity and damping parameters variation.
The main area of this study is framed by the passive isolation against shocks and vibration, due to the different technological equipments, of the sensitive embedded systems. Most of these isolation devices and systems are based on rubber elements and in some exploitation cases it was remarked an unusual behavior or an untimely evolution to a final damaged state.
The analysis is based on the large sets of virtual and instrumental tests, performed for different types of vibroisolation elements, with various structural and functional configurations. All of these was developed supposing the basic compressing and torsion rubber elastic elements, their working principle, and their functional restraints.
Through the comparative analysis of the acquired results, with the computational dynamics simulation, it was developed a few theoretical and operational models. Besides of the thermodynamics phenomenon, that are happen into the isolator, it was supposed the non-linear effects of damping and of rigidity that are usual characteristics of a real elements behavior. The reduction of transient states and decreasing the magnitude of permanent oscillations for specific parameters (like rigidity, damping, natural frequency, etc) around their reference value was the major and permanent purposes of this study.
The main concluding remark denotes the differences between simple theoretical models results and the real elements evolution under the charges. Because of the shifting and modification of the static and dynamic characteristics, the final evolution of the isolator may acquire unbalanced values for specific parameters. As a function of concrete and practical application of these rubber isolators it has to take into consideration the qualitative and quantitative deviation to the theoretical characteristics for a proper evolution such as it was imposed by the initial working conditions.

Brief Biography of the Speaker:
Silviu Nastac (born in 1971) received the PhD degree in Mechanical Engineering from University "Dunarea de Jos" of Galati, Romania, in 2006. He obtained a Master degree's in Computational Mechanics in 1997 and in Mechanics of Deformable Solids in 2004, at the same University. Since 1997 he is a senior research scientist at the Research Center for Mechanics of Machines and Technological Equipments, at Engineering Faculty in Braila, University "Dunarea de Jos" of Galati, Romania. He is a winner of the prize AROTEM of Romanian Association for Construction Technologies, Equipments and Mechanization in 2006. His main research topics include the theory of mechanics, dynamics, vibrations, acoustics, modelling and simulation of dynamic phenomenon, and virtual instrumentation. His work has been published in numerous referee journals, international conferences and several books. He has led and was involved in various research projects and has a plenary lecture at WSEAS Intl. Conf. Recent Advances in Automation & Information 2009. He was proposed and chair a structured session at Intl. Vilnius Conference on Sustainable Development in 2009. He is a member of International Institute of Acoustics and Vibration, International Association of Engineers, Romanian Society of Acoustics, Romanian Society for Theoretical and Applied Mechanics, and he is managing editor, associate editor and reviewer for national and international journals and conferences.




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