Wyniki wyszukiwania - BazTech

1

Optimisation of the parameters of a vibration damper installed on a historic bridge

Podwórna Monika, Grosel Jacek

Architecture Civil Engineering Environment

|

2023

|

Vol. 16, no. 4

93--101

EN

The paper presents theoretical analyses of renovating a historical bridge in order to decrease stresses. The installation of additional equipment, including a vibration absorber, is relatively easy to perform if such a need is indicated by the current bridge diagnostics or the monitoring of the structure’s vibrations. Moreover, absorbers could be mounted in such a way as not to alter the appearance of the historic structure. The authors focused on the problem of optimising the cooperation between a dynamic vibration absorber (DVA) and a structure under dynamic load moving with constant velocity. A simple degree of freedom (SDOF) system – as a model of the absorber and a multi-degree of freedom (MDOF) system – as the primary structure, were adopted in the calculations. Every force is regarded as a random variable, as well as interarrivals of moving forces. Two different situations and solutions were presented. The first case is when the stream of moving forces with a constant velocity is modelled as the filtered Poisson process. The second one when one of the forces is located in the point of the beam in which the response of the beam has the maximum value.

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

|

2021

|

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

Optimization of the semi-active vibration absorbers

Snitynskyy Volodymyr, Kernytskyy Ivan, Diveyev Bohdan, Horbay Orest, Fornalchyk Yevhen, Humenuyk Ruslan, Sholudko Yaroslav

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

|

2021

|

Vol. 30, No. 2

327--336

EN

In this paper, an efficient numerical approach is proposed to maximize the minimal damping of modes in a prescribed frequency range for general viscous tuned-mass systems. Methods of decomposition and numerical synthesis are considered on the basis of the adaptive schemes. The influence of dynamic vibration absorbers and basic design elastic and damping properties is under discussion. A technique is developed to give the optimal DVA’s for the elimination of excessive vibration in sinusoidal and impact forced system. One task of this work is to analyze parameters identification of the dynamic vibration absorber and the basic structure. The questions of robustness at optimization of DVA are considered. Different types of control management for semi-active DVA’s are applied. Examples of DVA’s practical implementation are presented.

4

Optimal configuration and parameters of translational dynamic vibration absorbers in vibroisolation of mechanical press

Łatas Waldemar, Dziechciowski Zygmunt

Vibrations in Physical Systems

|

2020

|

Vol. 31, nr 3

art. no. 2020314

EN

The paper deals with the problem of optimizing the positions and parameters of dynamic vibration absorbers for a mechanical press subjected to polyharmonic inertial excitation. Under the assumption of small vibrations a linear dynamic model of a rigid body performing a planar motion, on viscoelastic supports, with an attached system of translational tuned mass dampers is constructed. The problem of vibroisolation of the machine is presented, considering selected harmonics of the force transmitted to the ground, the solutions with a single DVA are proposed.

5

Effect of inerter in traditional and variant dynamic vibration absorbers for one degree-of-freedom systems subjected to base excitations

Barathwaaj Dheepakram Laxmimala, Yegateela Sujay, Vardhan Vivek, Suresh Vignesh, Kaliyannan Devarajan

Mechanics and Mechanical Engineering

|

2019

|

Vol. 23, nr 1

9--16

EN

In this paper, closed-form optimal parameters of inerter-based variant dynamic vibration absorber (variant IDVA) coupled to a primary system subjected to base excitation are derived based on classical fixed-points theory. The proposed variant IDVA is obtained by adding an inerter alone parallel to the absorber damper in the variant dynamic vibration absorber (variant DVA). A new set of optimum frequency and damping ratio of the absorber is derived, thereby resulting in lower maximum amplitudę magnification factor than the inerter-based traditional dynamic vibration absorber (traditional IDVA). Under the optimum tuning condition of the absorbers, it is proved both analytically and numerically that the proposed variant IDVA provides a larger suppression of resonant vibration amplitude of the primary system subjected to base excitation. It is demonstrated that adding an inerter alone to the variant DVA provides 19% improvement in vibration suppression than traditional IDVA when the mass ratio is less than 0.2 and the effective frequency bandwidth of the proposed IDVA is wider than the traditional IDVA. The effect of inertance and mass ratio on the amplitude magnification factor of traditional and variant IDVA is also studied.

6

Optimization of the impact multi-mass vibration absorbers

Kernytskyy I., Diveyev B., Horbaj O., Hlobchak M., Kopytko M., Zachek O.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

|

2017

|

Vol. 26, No. 3

394--400

EN

The problem of attaching dynamic vibration absorber (DVA) to a discrete multi-degree-of-freedom or continuous structure has been outlined in many papers and monographs. An impact damping system can overcome some limitations by impact as the damping medium and impact mass interaction as the damping mechanism. The paper contemplates the provision of DVA with the several of the impact masses. Such originally designed absorbers reduce vibration selectively in maximum vibration mode without introducing vibration in other modes. An impact damper is a passive control device which takes the form of a freely moving mass, constrained by stops attached to the structure under control, i.e. the primary structure. The damping results from the exchange of momentum during impacts between the mass and the stops as the structure vibrates. The paper contemplates the provision of the impact multi-mass DVA’s with masses collisions for additional damping. For some cases of DVA optimization such a design seems more effective than conventional multi-mass DVA with independent mass moving. A technique is developed to give the optimal DVA’s for the elimination of excessive vibration in harmonic stochastic and impact loaded systems.

7

On the optimum absorber parameters: revising the classical results

Puzyrov V., Awrejcewicz J.

Journal of Theoretical and Applied Mechanics

|

2017

|

Vol. 55 nr 3

1081--1089

EN

The dynamic vibration absorber is a kind of mechanical device with inertia, stiffness, and damping. Once connected to a given structure or machine, it is capable of absorbing vibratory energy. As a result, the primary system can be protected from excessively high vibration levels. In this paper, we deal with classical Den Hartog’s model to clarify the known results and improve the mathematical component of this approach. We suggest the optimal choice of absorber parameters, which is slightly different and more general analytical approach. The comparison of two methods of optimization is carried out, and the corresponding error of calculus is estimated.

8

Dynamic vibration absorbers – optimization and design

Pelekh Ya., Diveyev B., Hlobchak M.

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

|

2017

|

Vol. 6, No 1

23--30

EN

The main aim of the paper is improved dynamic vibration absorbers (DVA) design, taking into account the complex rotating machines dynamics. It is often impossible to balance the rotating elements so as to reduce the vibration to an acceptable level. The paper considers the provision of DVA or number of such DVA. Such originally designed DVA reduces vibration selectively in the maximum mode of vibration without introducing vibration in other modes. The result is achieved at a far lower expense than would be required to replace the concrete and steel foundation with a more massive one. By installing DVA, one can minimize excitation virtually at the source. In order to be more effective, a vibration absorption system should react in all the frequency domains. The present absorber also has as an advantage that it can be constructed so that it has a wide-range vibration absorption property. This construction allows for an easy connection of the above rotor equipment. In order to determine the optimal parameters of DVA, the complete modeling of the rotating machine dynamics is obvious. The two degrees of freedom model are totally inadequate to accurately calculate the vibration frequencies of the construction and therefore, for a sufficiently accurate determination of its dimensional characteristics so as to determine such frequencies. It is therefore necessary in practice to dimension the construction through more complex modeling. In particular, concentrated mass and rigidity calculation methods may be adopted based on an even more accurate theoretical determination. The numerical schemes (NS) row is considered for the complex vibration-excited constructions. Methods of decomposition and the NS synthesis are considered on the basis of new methods of modal synthesis. Complex NS are obtained of discretely-continua type, which enables in the adaptive mode to calculate tension not only in the continuum elements, but in the places of the most tension concentration in joints. Traditional design methodology, based on discontinuous models of structures and machines is not effective for high frequency vibration. The present research develops a modern prediction and control methodology, based on complex continuum theory and application of special frequency characteristics of structures. Complex continuum theory allows to take into consideration system anisotropy, supporting structure strain effect on equipment motions and to determine some new effects that are not described by ordinary mechanics of the continuum theory. The absorbers in accordance with this paper may be applied not only to electric machines ore aeronautic structures, but also to any other type of vibration-excited structure, such as cars, chisel installation, optical, magneto-optical disks, washing machines, refrigerators, vacuum cleaners, etc.

9

Application of the continuous dynamic absorbers in local and global vibration reduction problems in beams

Łatas W.

Vibrations in Physical Systems

|

2016

|

Vol. 27

245--254

EN

The paper deals with the application of the continuous dynamic absorbers in vibration reduction problems in beams. The Euler-Bernoulli beam of variable cross-section is subjected to the concentrated and distributed harmonic excitation forces. The beam is equipped with a system of the continuous vibration absorbers. The problem of the forced vibration is solved employing the Galerkin’s method and Lagrange’s equations of the second kind. Performing time-Laplace transformation the amplitudes of displacement may be written in the frequency domain, similarly the time-averaged kinetic energy of any part of the beam. The results of some local and global vibration control optimization problems concerning the placement and parameters of the continuous vibration absorbers are presented.

10

Parameter Determination of Dynamic Vibration Absorber for Application in Household Equipment

Gałęzia A., Waszczuk-Młyńska A.

Machine Dynamics Research

|

2016

|

Vol. 40, No. 1

83--94

EN

Quality of household equipment, such as washing machines or dishwashers is determined not only by quality of conformance or operational parameters, e.g. current consumption, but also by noise and vibrations generated during operation. The paper presents the analysis carried out in purpose of determination of parameters of the dynamic vibration absorber (DVA) for application in household equipment. Dynamic behavior of the water pump is analyzed and the discussion on determination of parameters of a DVA is carried out.

11

Sound transmission of sandwich beams with the dynamic vibration absorbers

Diveyev B., Kernytskyy I., Kopytko M., Konyk S., Kogut V.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

|

2015

|

Vol. 24, No. 2

120--132

EN

This study aims to predict the sound transmission properties of composite layered beams structures with the system of dynamic vibration absorbers (DVA’s). The effective stiffness constants of equivalent to lamina Timoshenko beam and their damping properties have been determined by using a procedure based on multi-level numerical schemes and eigen-frequencies comparison. The strategy of an anisotropic beam to the Timoshenko beam seem to be such: the raw of models can be applied at different vibration or static conditions of the plate by a suitable analytical ore approximation method, research of sensitiveness in relation to the parameters of fixing and material anisotropy, numerical experiments on identification of elastic modules, practical module identification by exploring different schemes of experimental setup and, finally, posterior analysis of identification quality. The combined method of identification was proposed on the basis of the simultaneous use of information on a homogeneous beam and beam with an internal layer, with identical mechanical properties to the homogeneous beam. Numerical evaluations obtained for the vibration of the equivalent Timoshenko beam have been used to determine the sound transmission properties of laminated composite beams with the system of DVA’s. The optimization of beams-DVA’s system sound absorption properties is performed in the low frequency range.

PL

W artykule zostały przebadane procesy pochłaniania hałasu w kompozytowych płytach warstwowych wyposażonych w dynamiczne absorbery drgań (DAD). Skuteczne współczynniki sztywności belki równoważnej do belki Tymoszenki i jej właściwości absorpcyjne zostały określone analitycznie przy użyciu wielopoziomowych systemów liczbowych i przez porównanie ich własnych częstotliwości drgań. Porównanie belek anizotropowych z belką Timoszenki przeprowadzono w następujący sposób: modele porównywały się dla różnych dynamicznych i statycznych właściwości płytek stosując metody analityczne i aproksymacyjne, badała się korelacja parametrów mocowania belki i anizotropii jej materiału, doświadczalnie ustalone zostały wartości modułów sprężystości, które uściślono w trakcie badań różnych schematów doświadczalnych instalacji, a następnie analizowano dokładność określania parametrów. Połączona metoda określania parametrów przewidywała analizę porównawczą jednorodnych i warstwowych płyt (płyty z wewnętrzną warstwą) o identycznych właściwościach mechanicznych. Wyniki liczbowe otrzymane w badaniu drgań równoważnej belki Timoszenki zostały wykorzystane do określenia parametrów kompozytów warstwowych płyt izolacji akustycznej wyposażonej w systemy DAD. Optymalizację właściwości izolacji akustycznej systemu płyta – DAD przeprowadzano w zakresie niskich częstotliwości drgań.

12

Optimal positions of tunable translational and rotational dynamic absorbers in global vibration control in beams

Łatas W.

Journal of Theoretical and Applied Mechanics

|

2015

|

Vol. 53 nr 2

467--476

EN

The paper discusses the problem of vibration of an Euler-Bernoulli beam with translational and rotational dynamic absorbers attached. The beam is subjected to concentrated and distributed harmonic forces. The equation of motion is solved using the Fourier method. The time Laplace transformation allows one to determine the amplitude-frequency characteristics of the beam deflection. The aim of the study is to examine the influence of positions of the translational and rotational dynamic absorbers on vibration suppression in the global control problem in beams. Numerical examples present reduction of kinetic energy of the cantilever beam with tunable absorbers over a wide range of frequencies. Optimal positions of the absorbers are obtained.

13

Multiple tuned tunable translational-rotational vibration absorbers in beam

Łatas W.

Vibrations in Physical Systems

|

2014

|

Vol. 26

145--152

EN

The paper deals with vibration of the beam with a system of the translational-rotational dynamic vibration absorbers attached. The beam is subjected to the distributed and concentrated harmonic excitation forces. Assuming small and linear vibration, an analytical Euler-Bernoulli model is applied and the solution to the problem is found with the use of Fourier method. Performing time-Laplace transformation the displacement amplitude of arbitrary point of the beam may be written in the frequency domain. The aim of the paper is to investigate the improvement of the efficiency of the translational-rotational absorbers compared with the translational ones in global vibration control problems. As an example reduction of the kinetic energy of the host structure is considered. Numerical simulations shows a considerable improvement of vibration reduction when the translational-rotational absorbers are utilized.

14

Acoustical properties of layered beams with attached dynamic vibration absorbers

Divejev B., Kernytskyy I., Grygoryshyn O., Kogut V.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

|

2012

|

Vol. 21, No. 4

227--238

EN

This study aims to predict the sound transmission properties of composite layered beams structures with the system of dynamic vibration absorbers (DVA’s). The effective stiffness constants of equivalent to lamina Timoshenko beam and their damping properties have been determined by using a procedure based on refined numerical schemes and eigen-frequencies comparison. Numerical evaluations obtained for the vibration of the equivalent Timoshenko beam have been used to determine the sound transmission properties of laminated composite beams with the system of DVA’s.

PL

W artykule zostały opisane wyniki badań dźwiękochłonnych właściwości kompozycyjnych wielowarstwowych struktur z systemem dynamicznych wibracyjnych absorberów (DWA). Stosując procedury usciślonych numerycznych schematów i porównania własnych częstotliwości, wyznaczone zostały efektywne stałe sztywności i tłumienia drgań belki Timoshenki odpowiednej do wielowarstwowej płyty typu sandwicz. Otrzymane dla ekwiwalentnej belki Timoshenki numeryczne oceny wibracji wykorzystane zostały do determinacji dźwiękochłonnych właściwości wielowarstwowej kompozycyjnej belki z systemem DWA.

15

Diskrete-continuum methods application for rotating machine-absorber interaction analysis

Stocko Z., Diveyev B., Topilnyckyj V.

Journal of Achievements in Materials and Manufacturing Engineering

|

2007

|

Vol. 20, nr 1-2

387-390

EN

Purpose: The main aim of this paper is improved dynamic vibration absorbers design with taking into accout complex rotating machines dynamic. Design/methodology/approach: The numerical schemes row is considered for the complex vibroexitated constructions. Methods of decomposition and the numerical schemes synthesis are considered on the basis of new methods of modal synthesis. Findings: Development of mathematical models of complicated machines and buildings in view of their interaction with system of dynamic vibration absorbers. Dynamic vibration absorbers - complicated rotating machines system design optimized on vibro- absorption properties. Research limitations/implications: The research must be done for non-linear rotor dynamics. Practical implications: The absorbers designed in accordance with this paper can be applied not only to electric machines or aeronautic structures, but to any other type of vibro-exitated structure, such as cars, chisel installation, optical, magneto-optical disks, washing machine, refrigerator, vacuum cleaner, etc. Originality/value: The paper has novelty both in theoretical, and in practical aspect. In order that optimal parameters of DVA be determinate the complete modeling of dynamics of rotating machine should be made. Traditional design methodology, based on discontinuous models of structures and machines are not effective for high frequency vibration.

16

Friction-Induced Vibrations : Excitation Mechanisms and Counter Measures

Popp K., Lindner M., Rudolph M.

Machine Dynamics Problems

|

2004

|

Vol. 28, No. 2

37-40

EN

Friction is an all-day-phenomenon and everybody is familiar with it. From an engineering point of view two different phenomena can be distinguished. First, the resistance against the start of a relative motion of bodies which is caused by the contact between these bodies. Secondly, the resistance against an existing relative motion of two contacting bodies. In the first case, the phenomenon is called static friction. It is of great use in technical applications as it enables for example fixing of parts by screws or driving of land vehicles by wheels. In the second case, the effort to sustain a sliding motion is called kinetic friction. Usually, this effect is unwanted in engineering because it is responsible for the transformation of kinetic energy into heat and, thus, additional energy consumption, as well as for the wear of parts by relative motion.