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Tłumienie drgań konstrukcji poddanej obciążeniu dynamicznemu

Podwórna Monika, Grosel Jacek

Materiały Budowlane

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2022

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nr 11

112--115

PL

W artykule opisano analizę belki obciążonej dynamicznie jako modelu zabytkowej konstrukcji mostowej, w której zastosowano tłumik drgań zmniejszający wytężenie konstrukcji przez redukcję drgań belki mostowej, które są wywołane działaniem stochastycznego strumienia sił poruszających się ze stałą prędkością. Wartość każdej z sił oraz czas między ich działaniem są traktowane jako zmienne losowe. Rozważono kilka kryteriów optymalizacji ugięcia belki mostowej z zamontowanym absorberem o różnych parametrach.

EN

This paper describes an example of a historic bridge structure in which a vibration damper is used to reduce the strain on the structure by reducing the vibrations of the bridge beam, which are caused by the action of a stochastic stream of forces moving at a constant speed, where each force and the times between arrival of the forces are treated as random variables. Several optimisation criteria were considered, based on measures of the variability of the random deflection of a bridge beam with an absorber installed with different parameters.

2

Optimisation of absorber parameters in the case of stochastic vibrations in a bridge with a deck platform for servicing pipelines

Grosel Jacek, Podwórna Monika

Studia Geotechnica et Mechanica

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2021

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Vol. 43, nr s1

492--500

EN

The paper focuses on the problem of optimising the cooperation between a dynamic vibration absorber (DVA) and a structure. The authors analyse a road beam bridge equipped with a working platform (deck) used to service pipelines installed on the structure. The paper studies the problem of choosing the optimal parameters for damping absorbers that reduce the random vibration of a beam subjected to a random sequence of moving forces with a constant velocity. The stochastic properties of the load are modelled by means of a filtering Poisson process. A single-degree-of-freedom (SDOF) absorber model with a multi-degree-of-freedom (MDOF) primary structure model are is considered.

3

Inertial position determination under vibration

Avrutov Vadym, Lakoza Serhii, Ryzhkov Lev, Sapegin Oleksandr

Vibrations in Physical Systems

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2020

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Vol. 31, nr 2

art. no. 2020201

EN

The main purpose of navigation systems is a position determination different moving objects. For standard inertial navigation systems algorithm, the initial position data are required. Normally these data may be determined by astronomical techniques or satellite and radio navigation systems. However, astronomical techniques depend on climate conditions and satellite and radio systems can be disturbed by electromagnetic countermeasures. It is proposed to use an Inertial Measurement Unit (IMU) and a navigation computer for autonomous determination of an initial position. IMU should be composed of three accelerometers, three gyroscopes and a signal processing circuit. The method proposed the latitude determination uses projections of the Earth’s rate measured by orthogonal IMU gyroscopes and projections of the gravity acceleration measured by orthogonal IMU accelerometers. Experimental tests of the IMU with a ring laser gyros triad and precision pendulum accelerometers confirmed the efficiency of the method on a fixed base. The behavior of the latitude determination under vibration is researched. The latitude determination under vibration was considered analytically by Power Spectral Density theory. It was estimated a variance of the latitude under the broad-band vibration. The method operability under harmonic and random vibration of the base at the real time is considered.

4

Modelling of the vibration exposure in typical working machines by means of random input signals

Maciejewski I., Krzyżyński T.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 3

1025--1037

EN

The aim of the paper is to formulate a generalized methodology of modelling random vibrations that are experienced by machine operators during their work. In the following paper, spectral characteristics of input vibrations are specified in such a way that the generated excitation signals are representative for different types of working machines. These signals could be used for determination and evaluation of risks from exposure to whole-body vibration.

5

Numerical studies of dynamic stability under small random parametric excitations

Bobryk R. V. R. V., Chrzeszczyk A.

Computer Assisted Mechanics and Engineering Sciences

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2010

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Vol. 17, no. 2-3-4

89-97

EN

An efficient numerical procedure is proposed to obtain mean-square stability regions for both single-degree-of-freedom and two-degree-of-freedom linear systems under parametric bounded noise excitation. This procedure reduces the stability problem to a matrix eigenvalue problem. Using this approach, ranges of applicability to the well-known stochastic averaging method are discussed. Numerical results show that the small parameter size in the stochastic averaging method can have a significant effect on the stability regions. The influence of noise on the shape of simple and combination parametric resonances is studied.

6

Statistical and equivalent linearization techniques with probability density criteria

Socha L.

Journal of Theoretical and Applied Mechanics

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1999

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nr 2

369-382

EN

The concept of statistical and equvalent linearization with probability density criteria for dynamic systems under Gaussian excitation is considered in the paper. New criteria of linearization and two approximate approaches are proposed. In the first one (statistical linearization) in order to establish the linearization coefficients and response characteristics the output probability density functions of statistic nonlinear element and the corresponding static linearized element are used in an iterative procedure. In the second approach (equivalent linearization) the direct minimization of a criterion based on output probability density functions of dynamic nonlinear system is proposed. The detailed analysis and numerical results are given for the Duffing oscillator.

PL

W pracy zaproponowano metodę statystycznej i równoważnej linearyzacji dla układów dynamicznych z wymuszeniami o charakterze białych szumów Gaussowskich i kryteriami w przestrzeni funkcji gęstości prawdopodobieństw. Przy wyznaczaniu współczynników linearyzacji i charakterystyk rozwiązań układu dynamicznego za pomocą metody statystycznej linearyzacji korzysta się z minimalizacji kryterium uwzględniającego różnicę wyjściowych funkcji gęstości prawdopodobieństw odpowiednio elementu nieliniowego zlinearyzowanego oraz pewnej procedury iteracyjnej. W przypadku równoważnej linearyzacji przeprowadza się bezpośrednią minimalizację kryterium uwzględniającego różnicę wyjściowych funkcji gęstości prawdopodobieństw odpowiednio układów dynamicznych nieliniowego i zlinearyzowanego. Szczegółową analizę i obliczenia numeryczne przeprowadzono dla oscylatora Duffinga.