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1

Temperature influence on non-linear harmonic vibrations Of plates made of viscoelastic materials

Litewka Przemysław, Lewandowski Roman

Engineering Transactions

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2020

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Vol. 68, iss. 2

159--176

EN

This paper is devoted to the analysis of ambient temperature influence on harmonic vibrations of von Kármán geometrically non-linear plates. The time-temperature superposition and the Williams-Landel-Ferry formula for the horizontal shift are used to modify the viscosity properties in the fractional Zener material model of viscoelasticity. The non-linear amplitude equation is obtained from the time-averaged principle of virtual work and the harmonic balance method. It is then solved after the finite element (FE) discretization using the continuation method to get the response curves in the frequency domain. Several numerical examples are solved and a significant influence of temperature on the resonance properties of the analysed plates is observed.

2

Some aspects of vibration control. Part I: Active and passive correction

Kosowski K.

Polish Maritime Research

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2004

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nr 4

22-27

EN

The paper presents a general approach to mechanical system modification aimed at controlling the steady harmonic vibrations by means of passive and active methods. The relaŹtive decrease of harmonic vibration amplitudes of selected elements of the mechanical system has been chosen as a measure of the quality of the introduced modification. The proposed theoretical method enables to determine the parameters of the system’s dynamic flexibility matrix, which show the most remarkable effect on the dynamic behaviour of the whole system. When active control is considered the method is useful in designing the structure and choosing the parameters of the control system. In certain in cases of self-excited vibration the approach helps examining the elements of the system, most responsible for this kind of excitation.

3

Harmoniczne wibracje w ocenie stanu technicznego turbogeneratora

Bytnar A.

Energetyka

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2001

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nr 5

243-246

PL

Omówiono harmoniczne wibracje elementów stojana turbogeneratora pochodzące od wymuszenia elektromagnetycznego. Przedstawiono wpływ obciążenia elektrycznego i czasu pracy turbogeneratora na parametry harmonicznych wibracji. Wyznaczono symptomy wibracyjne stanu technicznego stojana dużego turbogeneratora.

EN

Discussed are harmonic components of turbogenerator stator elements caused by electromagneti forces. Presented is an influence electrical load and time of turbogenerator operation on parameters of vibration harmonic components. Established are vibration symptoms of technical state of stator elements the turbogenerator of great power.

4

Pneumatic generator of monoharmonic vibrations with nonlinearity and feedback compensation.

Kuźniewski Bolesław

Advances in Manufacturing Science and Technology

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2000

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Vol. 24, nr 1

71-83

EN

The paper presents a model of piston pneumatic unit and analyses the dynamic process taking place in the appliance generating periodic sygnals. Nonlinearities and feedback occuring in flow and vibration process are described. A method of nonlinearity and feedback compensation by input parameters of air streams is presented.

PL

W pracy przedstawiono model tłokowego urządzenia pneumatycznego i dokonano analizy procesów dynamicznych takiego urządzenia generującego okresowe sygnały siły. Opisano występujące nieliniowości i sprzężenia procesów przepływowych oraz drgań. Przedstawiono metodę kompensacji nieliniowości i sprzężenia zwrotnego za pomocą regulacji parametrów wejściowych strumieni powietrza.

5

The rheological modelling and analysis of the fresh concrete compacting process subjected to harmonic vibrations

Bratu P., Mihalcea A.

Applied Mechanics and Engineering

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1999

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Vol. 4, no spec.

407-412

EN

The paper presents the rheological modelling of fresh concrete subjected to vibrations during the compacting process. The compacting efficiency can be estimated by means of the vibration transmissibility from the vibrating tool to the fresh concrete mass. Also the experimental results are presented.