Wyniki wyszukiwania - Biblioteka Nauki

1

Dynamic analyses of ships shafts lines

100%

Grządziela A.

Systems Science

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2008

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tom Vol. 34, no 3

45-50

EN

Ship propulsion plant usually works in a hard environment caused by static forces and permanent dynamic loads. Exceeding tolerable values of shaft alignments causes damage to radial and thrust bearings in a relatively short time. The modeling of dynamical reactions could bring information for the designer to recognize the level of hazard to a propulsion system. The paper presents a proposal of identification of the degree of hazard to ship shaft line due to forces of shaft misalignment. A theoretical analysis was made of the influence of changes in co-axiality of shafts resulting from the elastic deformations of a hull structure in the vicinity of the shaft bearing foundations. The main problem concerning naval vessels is the lack of dynamical requirements as regards the stiffness of the hull. The modelled signals were recognized within sensitive symptoms of two sub-models: a model of propulsion system and a model of shafts misalignment. Both sub-models allow testing forces and their responses in vibration spectrum using SIMULINK software.

2

Analysis Of Ship Shaft Line Coupling Bolts Failure

100%

Dymarski C. , Narewski M.

Journal of Polish CIMAC

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2009

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tom Vol. 4, no 2

33-40

EN

The ship propulsion shaft line is one of the most critical ship components having big influence on a ship safety. Because of that, there is well known need for proper shaft line survey either by ship crew, ship owner technical services as well as by classification society surveyors. One of the most dangerous and frequent kind of shaft line failures, especially on old ships, is a fatigue break of the collar coupling bolts. It usually causes the loss of the possibility to use the main propulsion system. In case of the bad weather and severe sea conditions it can lead even to the ship loss. The paper presents some data on failure statistics that was observed to shaft lines and propulsion system machinery. Furthermore, analyses of causes and generation mechanism of the mentioned fatigue breaks of the collar coupling bolts is presented.

3

Analysis methods of crankshaft's stiffness characteristics

75%

Murawski L. , Charchalis A.

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2013

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tom Vol. 20, No. 1

219--226

EN

Development of on-line diagnostic (monitoring) method of marine propulsion system working parameters is the authors' target. Crankshaft springing characteristics are one of the most important from the ships' main engines reliability point of view. Planned monitoring system will be able to verify crankshaft springing characteristics by continuous measurements of the crankshaft free-end's axial deformations. Development of the analysis methods of crankshaft's stiffness characteristics is the first step of planned SHM system. The main purpose of research is method developing of the springing analysis for the marine crankshafts in the high-power engines. Crankshaft modeling method, by Finite Element Method, has been discussed. Short overview of the crankshaft boundary conditions is presented. Bearings' oil film stiffness characteristics, ship hull stiffness characteristics and temperature deformation of the ship hull and main engine body are taking into account. Influence of the crankshaft's foundation stiffness on springing values is analysed. During the analyses it was proved that flexibility of engine foundation has a big influence upon the value of crankshaft springing. The authors' method of cylindrical mass and gas forces decompositions has been presented. Analysis of modeling precision of piston-crank system's forces has been performed. Results of calculations are well compatible in the terms of quality with the measurements data.

4

Transfer function for a controllable pitch propeller with added water mass

75%

Leshchev V. , Maslov I. , Palagin O. , Naydyonov A.

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2023

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tom nr 4

74--80

EN

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.

5

Metodyka obliczeń numerycznych ułożenia okrętowych linii wałów

63%

Murawski L. , Ostachowicz W. , Krawczuk M. , Żak A.

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tom z. 6

255-260

PL

W pracy przedstawiono nową metodę obliczeń optymalnego układania okrętowych linii wałów.; Zaprezentowano specjalistyczne programy komputerowe do wyznaczania linii ugięcia oraz obciążeń wału korbowego i linii wałów oraz do wyznaczania sztywnościowo-tłumieniowych charakterystyk dynamicznych łożysk okrętowych. Przeprowadzono analizę wpływu sposobów modelowania elementów układu napędowego na wyniki obliczeń parametrów pracy układu przeniesienia mocy.

EN

In the paper a new original method of marine shaft line alignment analysis is presented. Specialised numerical algorithms are used to determined shaft line deflection and crankshaft loading and also to determined stiff-dumping dynamic characteristics of the marine bearings. Modelling methods of the power transmission system and its involving on analysis results are discussed.