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Wyszukujesz frazę "vibrations" wg kryterium: Temat


Tytuł:
Some aspects of vibration control. Part I: Active and passive correction
Autorzy:
Kosowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/259185.pdf
Data publikacji:
2004
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
harmonic vibrations
passive control
active control
Opis:
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.
Źródło:
Polish Maritime Research; 2004, 4; 22-27
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some aspects of vibration control. Part II: An optimal active controller.
Autorzy:
Kosowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/259288.pdf
Data publikacji:
2005
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
active control
mechanical vibrations
optimal controller
Opis:
The paper presents a theoretical method for determining the optimal correction to be introduced in a mechanical system. The active control of harmonic vibrations may be achived by applying a control unit which ought to reduce the vibration amplitude of the selected elements of the system. The proposed method makes it possible to determine the controller parameters which provide an optimum value of the chosen quality index. This criterion includes the reduction of weighted amplitudes of the elements on the one hand, and minimizes energy of the control signal on the other. The described method is suitable for determination of an optimum controller of turbine rotor vibrations caused by bearing oil whip, bearing oil whirl or aerodynamic forces. For the case of rotor self-excited vibrations of aerodynamic type the linear model of excitations was compared with the neural network method.
Źródło:
Polish Maritime Research; 2005, 1; 28-31
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental research on hydroelastic behaviour of a tank model subdivided into liquid-filled compartments
Autorzy:
Trębacki, K.
Powiązania:
https://bibliotekanauki.pl/articles/258546.pdf
Data publikacji:
2008
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
vibrations
hydroelasticity
modelling
ship tanks for liquid
Opis:
The research was performed with the use of plexiglass models subdivided into 12 separate compartments. The compartments can be filled with a liquid. The model was excited to vibrations within a given frequency band by means of an exciter and accelerations were measured in selected points of the model. During measurement series oscillograms were obtained for various filling states at continuously changing range of measured frequencies. The oscillograms obtained for free vibrations measured on liquid-filled tank models were then processed. Results of the model tests were compared with those theoretically calculated for simple cases of tank-liquid system. The simple cases were used to test correctness of the elaborated computational program for determining hydrodynamic loads applied to tank walls. The application program for determining hydrodynamic internal loads was elaborated. Also, the influence of liquid filling state on values of loading, accelerations and wall deformations was demonstrated.
Źródło:
Polish Maritime Research; 2008, 4; 17-20
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A method for identification of non-coaxiality in engine shaft lines of a selected type of naval ships
Autorzy:
Grządziela, A.
Musiał, J.
Muślewski, Ł.
Pająk, M.
Powiązania:
https://bibliotekanauki.pl/articles/260536.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
shaft lines
vibrations
non-coaxiality identification
signal analysis
Opis:
A correctly designed machine is characteristic of low vibration values. However wear processes occur during its operation. They are accompanied by a lack of balance of its rotating parts and elements, which results in non-coaxiality of shafts. For this reason energy and dynamic load resulting from machine vibrations grows. In this case cause and effect are mutually connected by feedback, that inevitably leads to occurrence of a failure. This paper presents results of investigations carried out on the basis of vibration analysis of propulsion systems installed on 207P minesweepers. In view of specific features of their operation it is very important to ensure high level of reliability for them. For this reason was done an attempt to develop a method intended for identifying non-coaxiality of shaft line systems of engines propelling the ships. 16 characteristic features of recorded vibration signals were selected. As any of them has not satisfied criteria assigned to features which unambiguously determine state of reliability of shaft line systems, the investigations have been continued and as a result a novel method for non-coaxiality identification was proposed. The method consists in determining unserviceability clusters and assumes that characteristic features are of a concentrated character. This way a non-coaxiality of main engine shaft lines of 207P minesweepers could be detected. This paper presents the proposed method and results of its application to the case in question.
Źródło:
Polish Maritime Research; 2015, 1; 65-71
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diagnostics, maintenance and regeneration of torsional vibration dampers for crankshafts of ship diesel engines
Autorzy:
Homik, W.
Powiązania:
https://bibliotekanauki.pl/articles/259223.pdf
Data publikacji:
2010
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
crankshaft
torsional vibrations
damping of torsional vibrations
torsional vibration dampers
durability and reliability of multi-cylinder engine
diagnostics
maintenance
regeneration
Opis:
Periodically changeable gas and inertia forces which occur during operation of engine generate transverse, axial and torsional vibrations of crankshafts of multi-cylinder combustion engines. Torsional vibrations are those which endanger crankshafts of multicylinder combustion engines the most. In order to minimize their impact a torsional vibration damper is installed at crankshaft’s free end. Its technical state directly influences lifetime and reliability of engine. In this paper methods of diagnosing, maintenance and regeneration of torsional vibration dampers used in shipbuilding, are discussed. Also, are presented results of multi-year statistical investigations carried out in cooperation with a firm maintaining and regenerating ship engine torsional vibration dampers, which illustrate types of failures occurring in viscous and spring torsional vibration dampers.
Źródło:
Polish Maritime Research; 2010, 1; 62-68
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A discrete-continuous method of mechanical system modelling
Autorzy:
Hein, R.
Powiązania:
https://bibliotekanauki.pl/articles/258662.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
modelling
mechanical system
dynamic systems
vibrations
hybrid modelling methods
Opis:
The paper describes a discrete-continuous method of dynamic system modelling. The presented approach is hybrid in its nature, as it combines the advantages of spatial discretization methods with those of continuous system modelling methods. In the proposed method, a three-dimensional system is discretised in two directions only, with the third direction remaining continuous. The thus obtained discrete-continuous model is described by a set of coupled partial differential equations, derived using the rigid finite element method (RFEM). For this purpose, firstly the general differential equations are written. Then these equations are converted into difference equations. The derived equations, expressed in matrix form, allow to create a global matrix for the whole system. They are solved using the distributed transfer function method. The proposed approach is illustrated with the examples of a simple beam fixed at both ends and a simply supported plate.
Źródło:
Polish Maritime Research; 2017, S 1; 97-107
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis of possible assessment of hazards to ship shaft line, resulting from impulse load
Autorzy:
Grządziela, A.
Powiązania:
https://bibliotekanauki.pl/articles/259572.pdf
Data publikacji:
2007
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ship shaft lines
technical diagnostics
modelling
vibrations
underwater explosion
Opis:
This paper presents a proposal of identification of a degree of hazard to ship shaft line due to impulse load caused by underwater explosion. A theoretical analysis was made of influence of changes in co-axiality of shafts on second-kind critical velocities resulting from elastic deformations of hull structure in vicinity of shaft bearing foundations. Results are presented of pilotage tests of underwater explosion performed on training water area. A preliminary mathematical model of underwater explosion is given with taking into account mass of explosives and distance from the tested object. The drawn conclusions show a way of identification of hazard to shaft line by using spectral analysis and time - runs of vibration signals recorded at shaft bearings.
Źródło:
Polish Maritime Research; 2007, 3; 12-20
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations of harbour brick structures by using operational modal analysis
Autorzy:
Żółtowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/258750.pdf
Data publikacji:
2014
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
modal analysis
natural vibration frequency
stabilization diagram
structural vibrations
Opis:
Historic harbour brick objects are subject to large dynamic loads clearly reflected by generated vibration processes. The vibrations may affect state of serviceability of structures by lowering comfort of persons working there as well as possible reaching the level hazardous to safety of the structures. The effect of vibrations to structure is mainly manifested by additional stresses in a given cross-section, which are summed up with those resulting from static loads. Moreover often occur consequences associated with environmental conditions and fatigue of materials which accelerate destruction of the objects. Therefore the dynamic loads may cause damaging effects in buildings of various structural types or even lead to their catastrofic destruction. Judging the necessity of improving the quality assessment methods of building structures for purposes of estimation of their state as well as safety factors for brick structures (see PN-B- 03002 standard, p.3.1.3 and 4.6), the author of this work undertook an attempt to investigate destruction process of selected building structures by using the method of operational modal analysis.
Źródło:
Polish Maritime Research; 2014, 1; 42-53
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Truss harbor cranes modal design elements research
Autorzy:
Żołtowski, M.
Liss, M.
Żołtowski, B.
Melcer, J.
Powiązania:
https://bibliotekanauki.pl/articles/259900.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
construction vibrations
state of degradation
modal analysis
stabilization diagram
Opis:
Dockside cranes must meet the relevant strength requirements that provide usefulness and not endanger the safety of their use. The vibration effect on structural safety hazard results from the impact of horizontal forces caused by the transport of goods for loading and transverse forces caused by wind, which can be dangerous for correct functioning. In addition, there are often serious effects of climate-related impacts of the environment, material fatigue, which actuates the degradation state of the object. Dynamic loads may therefor cause random effects that devastate the structures or lead to their catastrophic destruction. Recognizing the need to improve the testing methods of crane structures in order to assess their condition and assess their safety factors - this paper attempts to develop a methodology for testing the degradation of the selected portion of a construction crane - using experimental modal analysis, realized in simulation tests in the Inventor environment as well as at test stand research.
Źródło:
Polish Maritime Research; 2015, 4; 84-92
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Remarks on aerodynamic forces in seals of turbine stages
Autorzy:
Stępień, R.
Kosowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/259359.pdf
Data publikacji:
2009
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
rotor dynamics
self-excited vibrations
aerodynamic forces
blade seals
turbine shrouds
Opis:
This paper presents results of numerical examination of flow through over-shroud seals of turbine stages. Various labyrinth seals of different configurations and number of sealing teeth were considered. It was demonstrated that results of investigations of isolated seals cannot be directly used for analyzing turbine stage operation. Such approach may lead to relatively large errors in determining value of aerodynamic force and direction of its action.
Źródło:
Polish Maritime Research; 2009, S 1; 58-63
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the modelling of aerodynamic force coefficients for over-shroud seals of turbine stages
Autorzy:
Włodarski, W.
Kosowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/259389.pdf
Data publikacji:
2009
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
rotor dynamics
self-excited vibrations
aerodynamic forces
blade seals
turbine shrouds
Opis:
This paper presents experimental investigations which made it possible to determine dynamic coefficients of labyrinth over-shroud seal of a model air turbine. The coefficients associate pressure forces with turbine rotor displacement, velocity and acceleration respective to turbine casing (linear model) and play important role in analyzing turbine-set dynamics. The obtained results indicated that involving serious errors can be expected in the case of application of the simplification consisting in neglecting inertia coefficients, proposed in the literature. It was simultaneously demonstrated that seals can be also met of weak damping qualities, for which to neglect damping coeffcients is allowable.
Źródło:
Polish Maritime Research; 2009, S 1; 71-74
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of vibrations of a liquid filled tank
Autorzy:
Trębacki, K.
Powiązania:
https://bibliotekanauki.pl/articles/259850.pdf
Data publikacji:
2008
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
modelling
vibrations
hydroelasticity
ship tanks for liquid fuels and liquefied gases
Opis:
Kinematic excitations provoke the motion and vibrations of the construction, which in turn considerably affects hydrodynamic loads generated on the walls of liquid cargo tanks. The issues of hydrodynamics also refer to the constructions fixed to the bottom, and those half-immersed, fully immersed, and floating (drilling platforms). They mainly concern ship tanks and oceanotechnical tanks. The theoretical and numerical analysis for long an short tanks, fully or partially filled with liquid has been performed. The determined hydrodynamic loads directly refer to the strength of the tank structure, which provides opportunities for determining the constructional strength of the entire hull. Extremely severe requirements are to be met by tanks used for carrying radioactive liquids, as an extremely high safety level is to be secured on all cargo carriers used in marine and land transport.
Źródło:
Polish Maritime Research; 2008, 3; 18-27
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Damping of torsional vibrations of ship engine crankshafts – general selection methods of viscous vibration damper
Autorzy:
Chomik, W.
Powiązania:
https://bibliotekanauki.pl/articles/260606.pdf
Data publikacji:
2011
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
torsional vibrations
torsional vibration damping
torsional vibration dampers
crankshaft
natural vibration frequency
Opis:
This paper describes causes of torsional vibrations generated in ship engine crankshafts. Means for damping the torsional vibrations as well as general methods for selection of viscous torsional vibration dampers for a given type of engine are also presented. Exemplary results of calculations connected with selection of a viscous torsional vibration damper intended for a six-cylinder engine, are attached.
Źródło:
Polish Maritime Research; 2011, 3; 43-47
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transfer function for a controllable pitch propeller with added water mass
Autorzy:
Leshchev, Volodimir
Maslov, Igor
Palagin, Oleksandr
Naydyonov, Andrii
Powiązania:
https://bibliotekanauki.pl/articles/34604683.pdf
Data publikacji:
2023
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
propulsion system
torsional vibrations
shaft line
added water mass
transfer function
propeller screw
Opis:
The relevance of this study lies in the fact that it presents a mathematical model of the dynamics of the propulsion system of a ship that takes into consideration the mass of water added to it. The influence of this phenomenon on the resonant frequencies of the propeller shaft is examined, and a transfer function for a controllable-pitch propeller is obtained for various operating modes. The purpose of the study is to improve the calculation of the dynamic operating modes of a controllable-pitch propeller by examining the features of a visual models. The VisSim software package is used in the study. A visual model is developed that considers the influence of the rotational speed on the value of the rotational inertia attached to the variable-pitch screw of the mass of water, and a special transfer function is proposed. The study shows that a transfer function of this type has a loop enabling negative feedback. An analysis of the operation of the propeller shaft at its resonant frequency is conducted based on the application of frequency characteristics using the transfer functions obtained. We show that in the low-frequency region, a consideration of the added rotational inertia using the proposed transfer function leads to a significant difference compared to the result obtained with the existing calculation method.
Źródło:
Polish Maritime Research; 2023, 4; 74-80
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of vibration parameters of ship gas turbine engines
Autorzy:
Grządziela, A.
Powiązania:
https://bibliotekanauki.pl/articles/259671.pdf
Data publikacji:
2006
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
turbiny gazowe
diagnostyka techniczna
drgania
bazy danych
gas turbine engine
technical diagnostics
vibrations
database
Opis:
This paper presents a method of vibroacoustic control of ship gas turbine engines. Analysis of recorded parameters makes it possible to identify unbalance of rotors, as well as sources of the unbalance. The presented software ANALIZA makes measured data storing and processing for engine diagnosing purposes possible.
Źródło:
Polish Maritime Research; 2006, 2; 22-26
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł

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