Wyniki wyszukiwania - Biblioteka Nauki

1

Vibration response of a disc brake: evaluation and design

100%

Abdo J. A. , Meinhardt G. A.

International Journal of Applied Mechanics and Engineering

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2006

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tom Vol. 11, no 3

467-479

EN

Noise and vibration is an increasingly important consideration in the design and study of disc brakes. Certain vibrations may only result in minor annoying squeals, while others may be severe enough to result in structural damage or failure. In either case, it is desirable to predict the conditions under which these vibrations arise, so that they may be controlled, or eliminated. This paper examines the contributions and interactions of four parameters to vibration response of a brake pad during braking: the applied load, the speed of rotation of the disc, the roughness of the disc and pad, and the Young's modulus of the disc and pad. The experiments are performed by simulating braking on a micro-tribometer. A statistical procedure, factorial design, is used to examine the effects and interactions of these four parameters on the vibration response of the pad in terms of the torque on the disc. Results suggested that the main effects Disc tangential velocity has the most significant influence followed by Young's modulus, and applied load. The model also suggested that the roughness is the least significant of the main effects, less significant than some interactions between other main effects, which indicate that the low frequency vibration at low speed is not necessarily associated with friction due to the low significance of the surface roughness.

2

Kryterium mechaniczne w ocenie dopuszczalnej obciążalności turbogeneratora

100%

Bytnar A.

Zeszyty Naukowe. Elektryka / Politechnika Śląska

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2001

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tom z. 177

9-14

PL

Omówiono zmodyfikowany wykres dopuszczalnych obciążeń turbogeneratora uwzględniający kryterium mechaniczne. Podano sposób wyznaczania krzywych ograniczających moc elektryczną maszyny przy założeniu nieprzekraczania dopuszczalnych wartości wibracji o częstotliwości 0.1 kHz rdzenia i korpusu stojana. Przedstawiono wyniki badań wibracyjnych turbogeneratorów, które sugerują konieczność rozszerzenia stosowanego kryterium mechanicznego. Przy ocenie stanu wibracyjnego stojana zaproponowano, aby brać pod uwagę harmoniczne wibracje o częstotliwości do 1kHz wszystkich głównych jego części (połączeń czołowych uzwojenia, rdzenia i korpusu). Przedstawiono zmodyfikowany wykres obciążalności turbogeneratora uwzględniający nadmierne średniokwadratowe wartości wibracji o częstotliwości do 1 kHz ww. części stojana.

EN

A modified diagram of turbogenerator permissible load with mechanical criterion taken into consideration is described. There is given a method of determination of the curves limiting the machine electrical power assuming that the core and frame vibrations of 0.1 kHz frequency do not exceed their permissible values. The presented results of vibrational tests suggest the need of widening the mechanical criterion being usually applied. It is proposed that for assessment of the stator vibrational state the harmonics of the frequencies up to 1 kHz for its all main parts (outhangs, core, frame) are to be taken into consideration. The modified diagram of turbogenerator permissible load takes into account the excessive mean-square values of vibrations of those parts with frequency up to 1kHz.

3

Harmoniczne wibracji stojana turbogeneratora

100%

Bytnar A. , Stawarz T.

Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały

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2000

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tom Vol. 48, nr 20

103-112

PL

Omówiono harmoniczne wibracji elementów stojana turbogeneratora pochodzące od wymuszenia elektromagnetycznego. Przedstawiono wpływ obciążenia elektrycznego i czasu pracy turbogeneratora na parametry harmonicznych wibracji. Wyznaczono symptomy wibracyjne stanu technicznego elementów stojana dużego turbogeneratora. Podano wyniki i interpretację pomiarów wibracji własnych elementów stojana turbogeneratora przy mechanicznym wymuszeniu udarowym.

EN

The harmonics of stator elements vibrations caused by electromagnetic forces are described. The influence of electrical load and elapsed time of generator operation on the vibration level is presented. Vibrational modes describing the technical condition of stator elements of large power turbogenerator have been determined. The results and interpretation of measurements of free vibrations forced by mechanical impact are given.

4

Free transverse vibrations of monoclinic rectangular plates with continuously varying thickness and density

88%

Kumar Y. , Tomar S. K.

International Journal of Applied Mechanics and Engineering

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2006

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tom Vol. 11, no 4

881-900

EN

Free transverse vibrations of a rectangular plate composed of a monoclinic elastic material are discussed. The plate is considered to be exponentially varying in density and thickness along one direction of the plate. Hamilton's principle is used to derive the equation of motion and its solution is obtained using Chebyshev collocation technique. Frequency equations are derived for three boundary value problems when two edges of the plate are simply supported and the other two have different possibilities, namely (i) C - S - C - S (ii) C - S - S - S (iii) C - S - F - S, where C, S and F denote the clamped, simply supported and free edge respectively. Effects of thickness and density variation on modes of vibrations have been analyzed. Numerical computations have been performed for a specific model of monoclinic plates and the results obtained are compared with those for orthotropic plates already given in Lal (2003).

5

Friction induced vibration of a very flexible shaft rotating slowly

88%

Kornyeyev S. , Sato Y. , Nagamine T.

International Journal of Applied Mechanics and Engineering

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2006

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tom Vol. 11, no 3

491-499

EN

High frequency vibration was observed in operation of a soot-blower. To clarify its mechanism analysis and experiment was done on a system consisting of a flexible shaft rotating slowly, on which friction acts tangentially at an intermediate position. Analytical results show that the real part of an eigenvalue does not always decrease monotonically with the order of mode. Therefore, some higher modes may appear more prominently. Large vibration is observed in experiment where real part of an eigenvalue is large.

6

Ocena stanu zagrożenia polskiego środowiska hałasem i wibracjami

88%

Zakrzewski T.

Zeszyty Naukowe. Budownictwo / Politechnika Śląska

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2000

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tom z. 88

265-270

EN

It results from the carried out research and analyses of the distribution of the noise level which exists in the natural environment that the noise emitted by all the sources present in the environment makes a serious threat for human beings. In the paper, for documentary evidence of the degree of exposure of our environment to noise and vibrations, the characteristics of the equivalent sound level emitted by the means of the road, rail, our transport, and industry are presented.

7

W drodze do Unii Europejskiej

88%

Berezowska-Apolinarska K.

Przegląd Komunalny

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2002

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tom nr 7

36-37

PL

W drodze Polski do Unii Europejskiej, na podstawie postanowień Układu Europejskiego z 1991 r., następuje stopniowe zbliżanie przepisów prawa polskiego do prawa UE. Przekształcanie przepisów następuje także w zakresie ochrony środowiska, w tym w dziedzinie ochrony przed hałasem.

8

Mathematical model of mechanical system of vibrational volumetric treatment

88%

Stotsko Z. , Sokil B. , Topilnytskiy V.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2004

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tom z. 23

401-407

EN

In order to calculate designed parameters for vibrational machine of volumetric vibrational treatment with the purpose to increase its productivity, the technique for investigating its dynamics based on non-linear complex mathematical model of the "vibromachine - treating medium" - system is suggested in this paper. As an example models of the machine with two independently driven vibrational exciters and the treating medium of its container are described.

9

W STRONĘ JEDNEJ EUROPY. Drgania miejscowe

88%

Kowerski A.

Ochrona Pracy

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1992

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tom 46

|

nr 08

10

An influence of vibration on the human brain

88%

Todua F. , Khomeriki O. , Beraia M.

Biocybernetics and Biomedical Engineering

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2000

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tom Vol. 20, no. 2

79-83

EN

Brain of 115 engine drivers and their assistance at the Railway of the Georgia Republic were studied. The most pronounced atrophical changes of temporal lobe and cerebellum were noted as effect of vibration. These changes were more evident than changes caused by age. Damage factor might be a chronic trauma to the brain. The results are confirmed by experimental materials.

PL

W artykule przedstawiono wstępnie oddziaływanie wibracji mechanicznych na zmiany patologiczne mózgu. Zwrócono uwagę na niekorzystne zjawiska będące wynikiem długotrwałego przebywania w obszarze oddziaływania wibracji, w szczególności w miejscach pracy, np. w kabinach elektrowozów. Przedstawiono również badania eksperymentalne przeprowadzone na grupie 115 maszynistów kolejowych z Gruzji, które potwierdziły występowanie zmian patologicznych wyraźnie większych niż wynikałoby to z procesu starzenia się.

11

Ochrona środowiska przed hałasem i wibracjami w świetle obowiązujących przepisów prawnych

88%

Wojciechowska M.

Prace Instytutu Techniki Budowlanej

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1999

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tom R. 28, nr 1

75-80

PL

Przedstawiono aktualnie obowiązujące przepisy prawne dotyczące ochrony środowiska przed hałasem i wibracjami, ze szczególnym uwzględnieniem znowelizowanej ustawy o ochronie i kształtowaniu środowiska.

12

Projekt roboczego obuwia ochronnego o właściwościach przeciwwibracyjnych

88%

Bris P. , Hlavacek P. , Mladek M.

Przegląd Skórzany

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1988

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tom 43

|

nr 11

13

Skutki wadliwych maszyn

88%

Solecki L.

Nowoczesne Rolnictwo. Nauka, Doradztwo, Praktyka

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1996

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tom 03

|

nr 09

32-33

14

Modelling of vibration of moving blade packet

75%

Zeman V. , Kellner J.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2006

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tom z. 31

155-160

EN

This paper deals with a modelling and a sensitivity modal analysis of the moving blade packet. The blades are considered as ID continuum mutually coupled by a shrouding. The mathematical model makes possible to analyse an influence of centrifugal forces, gyroscopic effects, blade's elastic seating to bladed disk and material and geometrical parameters of the shrouding on moving blade packet modal properties.

15

Modelling of pipeline systems conveying fluid under large displacements and rotations

75%

Dupal J.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2006

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tom z. 31

7-10

EN

The paper deals with modelling approach to the pipeline vibration under flowing fluid influence respecting large displacements and rotations but smali strains and thus the validity of Hoocke's law is supposed. A corotational formula is used for deriving of equation of motion and individual element matrices expressing inner and inertia forces. In case of straight elements a Green's strain tensor relative to corotational coordinate system is used. This tensor can not be replaced by Cauchy strain tensor inspite the deformation is smali because the Cauchy strain tensor is not able to respect the membrane deformation [1]. The second Piola-Kirchhof tensor is used as a measure of stress. The matrices corresponding to the inner and inertia forces are displacement and velocity dependent and for this reason the resulting equation of motion is geometrically nonlinear.

16

Problemy zrównoważonego rozwoju w analizie wibroakustycznej środowiska pracy

75%

Wawrzeńczyk-Zdżyłowska A. , Zawieska W. M.

Bezpieczeństwo Pracy : nauka i praktyka

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2011

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tom nr 12

10-13

PL

W artykule przedstawiono problematykę rozwoju zrównoważonego w odniesieniu do analizy wibroakustycznej środowiska pracy. Podano zasady tworzenia wskaźników rozwoju zrównoważonego oraz wskaźników wibroakustycznych środowiska pracy: globalnego WG i cząstkowych Wi. Zasady te zilustrowano przykładową analizą klimatu akustycznego przeprowadzoną dla hali przemysłowej.

EN

This article presents problems of sustainable development in relation to a vibroacoustic analysis of the work environment. It discusses rules of creating indicators of sustainable development as well as vibracoustic indicators of the work environment: global WG and partial Wi. A sample analysis of the acoustic climate performed in an industrial yard illustrates those rules.

17

Analiza możliwości detekcji zdarzeń krytycznych z udziałem motocykla. Cz. I. Wykorzystanie drgań i wibracji motocykla

75%

Pietrasieński J. , Rodzik D. , Bużantowicz W. , Miernik J. , Paramuszczak K.

Mechanik

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2012

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tom R. 85, nr 7CD

723--730

PL

W referacie poddano analizie możliwości detekcji zdarzeń krytycznych z udziałem motocykla na podstawie drgań i wibracji. Pod tym kątem zaprezentowano wybrane wyniki rejestracji parametrów ruchu motocykla w warunkach miejskich i terenowych. Zwrócono uwagę na główne problemy występujące podczas detekcji i analizy zarejestrowanych przebiegów.

EN

In this paper, the possibilities of critical incident detection with motorcycle’s participation are discussed. The first part of article refers to usage of vibrations. The results of motorcycle’s movement parameters registrations (in the urban environment and in the terrain) are presented. The major problems appearing during detection and analysis of registered parameters are highlighted.

18

Increase of reliability and tribological characteristics of gyroscopes

75%

Kovalev E. , Ignatiev M. , Wisniewska-Weinert H. , Leshchynsky V.

International Journal of Applied Mechanics and Engineering

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2006

|

tom Vol. 11, no 3

501-506

EN

Now gyroscopic devices are applied in many industrial areas. Alongside with traditional mechanical gyroscopes, the increasing weight is got by systems of mechanical group realizing more perfect principles of their construction, such as gyroscopes with non-contact levitating rotor. However, complication of gyroscopic devices entails a number of problems which are not solved till now. One of the most critical problems is reliability of a rotor and stator at an emergency situation. This situation is characterized by "landing" of a rotor on stator. It leads to destruction of elements of stator because of high tangential loading (friction coefficient of ferrite is more than 0.25). Special coatings for ferrite materials have been developed to decrease friction coefficient (to 0.07) and to provide stator and rotor reliability even under emergency situation: amorphous (Al-Si)N magnetron coating and coating based on MoS2 nanoparticles with polymer binder. Tests of the developed coating was realised in vacuum [...] at loading 1-5 MPa and sliding velocity of 0.2-1.0m/s. The test results show that problem of durability of gyroscopes with non-contact levitating a rotor can be successfully solved with the help of new coatings.

19

A sub-parametric shear deformable element for free vibration analysis of thick/thin rectangular plates with tapered thickness

75%

Manna M. C.

International Journal of Applied Mechanics and Engineering

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2006

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tom Vol. 11, no 4

901-913

EN

A sub-parametric shear deformable element is proposed for free vibration analysis of isotropic plates with linearly varying thickness in one direction. The element has sixteen nodes and thirty-six degrees of freedom. The transverse displacement and bending rotations are taken as independent field variables. The polynomials used to express these variables are of the same order. The geometry of the element is defined by a polynomial of lower order than the polynomials used for field variables. The entire formulation is made based on first-order shear deformation theory (FSDT). The rotary inertia is included in the consistent mass matrix for the analysis. Isotropic plates with different thickness ratios (varying from 0.01 to 0.2), tapered ratios, aspect ratios and boundary conditions are analyzed. The results obtained by the present element show an excellent agreement with the available published results. Some numerical results have been given as new results.

20

Elastic stability of square stiffened plates with cutouts under biaxial loading

75%

Srivastava A. K. L. , Datta P. K.

International Journal of Applied Mechanics and Engineering

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2006

|

tom Vol. 11, no 2

421-433

EN

A finite element method for the buckling loads on a longitudinally square stiffened plate with square cutouts is investigated under various combinations of biaxial loading at the plate boundary. The forces are assumed to act in the plane of the undeformed middle surface of the plate. The characteristic equations for the natural frequencies, buckling loads and their corresponding mode shapes are obtained from the equation of motion. The buckling load parameter for various modes of the stiffened plate with square cutouts subjected to in-plane biaxial loads, has been determined for various edge conditions. Numerical results are presented for a range of hole to plate size from 0 to 0.8. In the structural modeling, the plate and the stiffeners are treated as separate elements where the compatibility between these two types of elements is maintained. The present approach is more flexible than any other finite element modeling in that the mesh division is independent of the location of the stiffeners.