National Repository of Grey Literature 18 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Experimental and theoretical stability analysis of damped auto-parametric pendulum
Pospíšil, Stanislav ; Fischer, Cyril ; Náprstek, Jiří
The article describes an experimental and theoretical treatment of the auto-parametric pendulum damper modelled as a double-degree-of-freedom (DDOF) system. It is strongly non-linear, with the harmonic excitation being applied in the suspension point and interpreted for instance as an excitation by wind. The stability of the motion in a vertical plane is analysed in the meaning of semi-trivial vibration. This effect of stability loss and possible stability regain is very important from practical point of view, because the motion of an damper beyond the stability limits may act negatively and thus endanger the structure itself. Special experimental frame was developed.The stability of the system is analysed experimentally and compared with theoretical results.
Dvě rovnice popisjící kyvadlový tlumič
Fischer, Cyril ; Náprstek, Jiří
The pendulum damper modelled as a two degree of freedom strongly non-linear auto-parametric system is investigated using two approximate differential systems. Uni-directional harmonic external excitation at the suspension point is considered. Semi-trivial solutions and their stability are analyzed. The thorough analysis of the non-linear system using less simplification than it is used in the previous paper is performed. Both approaches are compared and conclusions are drawn.
Rezonanční chování kulového kyvadlového tlumiče
Fischer, Cyril ; Náprstek, Jiří
The pendulum damper modelled as a two degree of freedom strongly non-linear auto-parametric system is investigated using two approximate differential systems. Uni-directional harmonic external excitation at the suspension point is considered. Semi-trivial solutions and their stability are analyzed. The thorough analysis of the non-linear system using less simplification than it is used in the previous paper is performed. Both approaches are compared and conclusions are drawn.
Influence of random material heterogeneity on longitudinal harmonic wave propagation
Náprstek, Jiří
The paper deals with mathematical modelling and properties of linear longitudinal wave propagating in one dimensional body with random imperfections in material density and Young modulus.
Post kritické limitní stavy a nestacionární odezva aeroelastického systému
Náprstek, Jiří ; Pospíšil, Stanislav ; Fischer, Cyril
The paper deals with the clasification of stability and limit cycles of two dimensional aeroelastic system.
Numerické a experimentální řešení nelineární aeroelastické odezvy nosníku mostu
Pospíšil, Stanislav ; Král, Radomil ; Náprstek, Jiří ; Hoffer, R. ; Lachmann, S.
Analysis of the bridge girder under self-excited load is performed numericaly and experimentally.
Numerická analýza v Fokker-Planckovy rovnice pro soustavy s multiplikativními a aditivními šumy
Náprstek, Jiří ; Král, Radomil
In the present study simple conditions are selected to demonstrate that the idea of FEM application for this purpose is realistic. FEM abalities are demonstrated discussing a couple of single degree of freedom systems.
Autoparametrický charakter konstrukce spřažené se sférickým kyvadlovým tlumičem
Náprstek, Jiří ; Fischer, Cyril
Dynamic behaviour of many engineering structures can be considered as auto-parametric systems. By way of examples can be mentioned wind induced vibrations of high slender structures with spherical pendulum damper, aeroelastic interactions and post-critical effects due to selfexciting processes, etc.Auto-parametric systems have been intesively studied for the last three decades.
Základní rysy numerického řešení Fokker-Planckovy rovnice pomocí metody konečných prvků
Náprstek, Jiří ; Král, Radomil
The Fokker-Planck equation represents a powerful tool for an investigation of probabilistic properties of dynamic systems subjected to random excitation.The paper deals with a possibility to solve this equation using Finite Element Method - FEM. Specific properties of the Fokker Planck operator have been respected and special problem oriented elements have been developed.
The influence of non-proportional damping on forced vibration of continuous multispan girder
Hračov, Stanislav ; Náprstek, Jiří ; Pospíšil, Stanislav
The article deals with an influence of the proportional and non-proportional damping on forced vibration of continuous multispan girder. the solution is formulated in generalized coordinates, which are the eigen-functions of undamped system. The solutions of classical method and analysis including non-proportional damping are comparing.

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