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1

Ograniczanie drgań układu wentylator-silnik elektryczny na przykładzie remontowanej instalacji wentylacyjnej - studium przypadku

Walaszczyk Juliusz

Instal

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2024

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nr 2

36--43

PL

W ostatnich latach coraz mniej uwagi przykłada się do elementów związanych z prawidłową amortyzacją maszyn wirnikowych (wentylator - silnik, pompa - silnik itd.). W pogoni za ograniczeniami, przede wszystkim kosztów inwestycyjnych, nierzadko podejmowane są pochopne decyzje związane z „odchudzaniem” ram podporowych czy fundamentów pod maszyny wirnikowe. Dla zobrazowania skutków takich działań w artykule przedstawiono i omówiono wyniki pomiarów drgań wykonanych w obiekcie rzeczywistym przed oraz po wymianie instalacji wentylacyjnej obsługującej halę przemysłową. Wyniki pomiarów zestawiono z wynikami obliczeń wykonanych na podstawie 3 metod teoretycznych. Wykazano, że odpowiednia masa ramy podporowej oraz staranne wypoziomowanie układów mają decydujący wpływ na uzyskiwane amplitudy drgań. Tezę tę udowodniono poprzez ograniczenie drgań z 16,39 mm/s RMS do 4,23 mm/s RMS. Wykazano, że regularne monitorowanie amortyzacji może skutecznie i szybko doprowadzić do wykrycia problemów związanych z pracą wentylatorów i silników (uszkodzenie łożysk, niebezpieczne amplitudy drgań przegród budowlanych).

EN

In recent years, less and less attention has been paid to elements related to the proper depreciation of rotating machines (fan - electric motor, pump - electric motor, etc.). In the pursuit of reductions, especially in investment costs, hasty decisions are often made related to “slimming” support frames or foundations for rotating machines. To illustrate the effects of such actions, the article presents and discusses the results of vibration measurements performed in a real facility before and after replacing the ventilation installation that serves an industrial hall. The measurement results were compared with the results of calculations made based on 3 theoretical methods. It has been shown that the appropriate mass of the support frame and careful levelling of the systems have a decisive impact on the vibration amplitudes obtained. This thesis was proven by reducing vibrations from 16.39 mm/s RMS to 4.23 mm/s RMS. It has been shown that by regular monitoring of isolators depreciation one can effectively and quickly detect problems related to the operation of fans and electric motors (damage to bearings, dangerous vibration amplitudes of building partitions).

2

On the use of viscoelastic materials characterized by Bayesian inference in vibration control

Préve Cíntia Teixeira, Balbino Fernanda Oliveira, Ribeiro Junior Paulo Justiniano, de Oliveira Lopes Eduardo Márcio

Journal of Theoretical and Applied Mechanics

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2021

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Vol. 59 nr 3

385–-399

EN

Viscoelastic materials are used to reduce vibrations in mechanical systems due to their con- trol efficacy. Considering that the dynamic behavior of those materials may be described by means of complex moduli, and experimental data may present ucertainties, an alternative is to use probabilistic methods, especially the Bayesian inference approach. By that approach, probability distribution functions are obtained for parameters of a model which describes the behavior of a given material. The present work employs a viscoelastic material modeled by the Bayesian approach in two vibration control actions, namely: a) use of vibration isolators; b) use of dynamic neutralizers. Transmissibility and receptance curves are displayed as well as dimensions of the control devices. Performance predictions are carried out in both cases. It is shown that the Bayesian approach can favourably reflect the presence of the uncertain- ties and advance their effects. Thus, more information can be provided for the designer of viscoelastic vibration control devices to anticipate eventual corrective measures.

3

Wyniesione lądowiska dla helikopterów na budynkach szpitalnych

Wąchalski K.

Inżynier Budownictwa

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2018

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nr 4

84--89

4

Investigation on a quasi-zero-stiffness vibration isolator under random excitation

Wang Y., Li S., Cheng C.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 2

621--632

EN

The dynamic response and isolation performance of a Quasi-Zero-Stiffness (QZS) vibration isolator using inclined springs as negative stiffness correctors under random excitation are presented in this paper. The probabilistic linearization method is employed to determine the dynamic response of the QZS vibration isolator and compared with the exact solution based on the Fokker-Planck-Kolmogorov (FPK) equation and the equivalent linearization method. Two performance indexes (Mean Square Relative Displacement (MSRD) and Mean Square Acceleration (MSA)) are considered to evaluate the isolation performance of the QZS vibration isolator under random excitation and compared with the equivalent linear vibration isolator. The results show that the MSRD of the QZS vibration isolator is always lower than the equivalent linear vibration isolator, while the MSA of the QZS vibration isolator can be larger or lower than the equivalent linear vibration isolator based on the values of damping ratio and spectral density of the random excitation

5

Load-Dependent Controller of the Active Seat Suspension with Adaptive Mass Recognizing

Maciejewski I.

Acta Mechanica et Automatica

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2012

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Vol. 6, no. 2

66-70

EN

The paper deals with the load dependent control system of active seat suspension. This system based on the primary controller which evaluates the desired active force, the reverse model which calculates the input signal of force actuator and the adaptation mechanism which recognizes the actual mass loading. An optimisation procedure additionally presented in this paper allows to find the primary controller settings that minimizes the vibration of cabin's floor transmitted to operator's seat at the pre-defined value of the maximum relative displacement of suspension system.

6

Vibration isolators test bench

Pobedin A., Kosov O., Shekhovtsov K.

Journal of KONES

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2011

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Vol. 18, No. 1

457-462

EN

The description of the scheme and design of the test bench for testing vibration isolators intended for use in the vehicle's cabin suspension. Test bench construction allows to implement a wide range of loadings on vibration isolator of the vehicle cabin, to investigate the impact of the loading's arm changing and to perform analysis of the vibration isolator’s elastic and damping characteristics changing impact on cushioning quality. Variant of the test bench construction modernization, which can allow applying typical exploitation loads, which include vertical and lateral components, is described. We propose a scheme of forced oscillations excitation system on the test bench by cam-eccentric mechanism. It includes a DC motor with stepless frequency regulation and with cams of different shape on its shaft, which affect the contact surface of the test bench's vertical H-beam of a rocker arm. We also propose a scheme of forced oscillations excitation system on the test bench by inertial exciter. It includes a DC motor with stepless frequency regulation with inertial vibration exciter on its shaft, which consists of a mass, placed eccentrically relative to the shaft axis. There are two variants of the test bench scheme – with the forced oscillations excitation device and without it.