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1

Influence of the variability of the shape of short axisymmetric rods on the value of basic natural frequency of longitudinal vibrations

Kozień Marek S.

Vibrations in Physical Systems

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2021

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Vol. 32, nr 2

art. no. 2021212

EN

Rods with a relatively short length in relation to their transverse dimensions with a variable cross-section along the axis, subjected to longitudinal vibrations, have the character of stocky rods, for which the classic geometric principles used for rods are not fully met. For small engineering elements, the postulated design frequencies of natural vibrations in the very high cycle fatigue analyses reach the values of a dozen or so, small, several dozen kHz. In the article, the sensitivity of the value of the basic natural frequency to the change in the shape of the element is analysed and discussed. The analysis is conducted using finite element method.

2

A semi-analytic approach to calculating the Strehl ratio for a circularly symmetric system.Part 2: dynamic wavefront

Castaño-Fernandez A. B., Martínez-Finkelshtein A., Iskander D. R.

Optica Applicata

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2018

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Vol. 48, nr 2

211--223

EN

Close-form expression for the Strehl ratio calculated in the spatial frequency domain of the optical transfer function (SOTF) is considered for the case of time-varying dynamic optical system that has circular symmetry. Specifically, closed-form expressions for the temporally averaged SOTF are considered, which can be easily evaluated numerically (what we call a semi-analytic solution). As for the case of a static wavefront, described in Part 1 of this work, it is shown that the proposed methods are computationally more efficient than the commonly used approach based on the discrete Fourier transform.

3

Influence of Damping on Transverse and Longitudinal Vibrations of T-type Frame

Sochacki W., Bold M.

Machine Dynamics Research

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2017

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Vol. 41, No. 1

143--154

EN

In this paper, the problem of transverse and longitudinal damped vibration of T-type frame was formulated and solved. The vibration energy dissipation in the model occurs as a result of internal, constructional and external damping. Damping in adopted model is a result, of taken into account viscoelastic material of beams that modelled the system, motion resistance in frame supports and influence of medium surrounded the frame. Damped frequencies of vibrations and degree of amplitude decay were calculated. The study also presents eigenvalues of system vibration with respect to changes in damping coefficients and system geometry for selected rigidity of springs.

4

Modelowanie i eksperymentalna identyfikacja parametrów hydraulicznego stabilizatora drgań wzdłużnych ładowarki łyżkowej

Kosiara A.

Wybrane Problemy Inżynierskie

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2011

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nr 2

207-212

PL

W pracy przedstawiono zagadnienia związane z modelowaniem pasywnych hydraulicznych stabilizatorów kątowych drgań wzdłużnych kołowych czołowych ładowarek łyżkowych. W szczególności przeanalizowano wpływ na wyniki obliczeń linearyzacji modelu stabilizatora. W pracy omówiono także eksperymentalną identyfikację wybranych parametrów modelu układu stabilizacji drgań.

EN

In article there are explain some problems connected with modelling of passive hydraulic longitudinal oscillation stabilizers in front wheeled loaders. Particularly, the influence on results of linearization of stabilizer's model was analyzed. Experimental identification of selected parameters of the model was also discussed.

5

Wpływ parametrów drgań wzdłużnych i sztywności styku na poziom redukcji siły napędu w ruchu ślizgowym

Gutowski P., Leus M.

Tribologia

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2011

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nr 4

113-123

PL

W pracy zaprezentowano wyniki analizy symulacyjnej wpływu amplitudy prędkości drgań wymuszonych stycznych wzdłużnych i sztywności kontaktowej stycznej styku na siłę napędu konieczną do wprawienia ciała w ruch ślizgowy i utrzymania tego ruchu. Analizę przeprowadzono przy wykorzystaniu klasycznego statycznego modelu tarcia Coulomba i dynamicznego modelu tarcia Dahla. Wyniki badań symulacyjnych zweryfikowano na podstawie wyników badań doświadczalnych przeprowadzonych na specjalnie w tym celu zbudowanym stanowisku badawczym.

EN

The simulation tests results of the influence of amplitude of longitudinal tangential vibrations velocity as well as the influence of contact shear stiffness on driving force which is necessary for initiation and maintenance of the sliding motion are presented in this paper. Analyses were performed with the use of Coulomb’s classical static model of friction and with the use of Dahl’s dynamic model. The results of simulation tests were verified. Verification was made based on the results of experimental tests, which were carried out on a stand especially designed for this purpose.

6

Longitudinal vibrations of mechanical systems with the transportation effect

Buchacz A., Żółkiewski S.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 32, nr 1

29-36

EN

Purpose: this thesis purpose is a new way of modelling systems working with high speeds of mechanisms. Systems are analyzed with taking into consideration the rotational movement and with criterions of using materials with high flexibility and high precision of work. The dynamical analysis was done with giving into consideration the interaction between working motion and local vibrations. During the motion a model is loaded by longitudinal forces. Design/methodology/approach: equations of motion were derived by the Lagrange method, with generalized coordinates and generalized velocities assumed as orthogonal projections of individual quantities of the rod and manipulators to axes of the global reference frame. Findings: the model of longitudinally vibrating systems in plane motion was derived, after that the model can be transformed to the dynamical flexibility of these systems. Derived equations are the beginning of analysis of complex systems, especially can be used in deducing of the substitute dynamical flexibility of multilinked systems in motion. Research limitations/implications: mechanical systems vibrating longitudinally in terms of rotation were considered in this thesis. Successive problem of the dynamical analysis is the analysis of systems in spatial transportation and systems loaded by transversal forces. Practical implications: effects of presented calculations can be applied into machines and mechanisms in transportation such as: high speed turbines, wind power plant, water-power plants, manipulators, aerodynamics issues, and in different rotors etc. Originality/value: the contemporary analysis of beams and rods were made in a separate way, first working motion of the main system and next the local vibrations. A new way of modelling took into consideration the interaction between those two displacement. There was defined the transportation effect for models vibrating longitudinally in this paper.

7

Badania doświadczalne i modelowanie oddziaływania drgań stycznych wzdłużnych na siłę napędu w ruchu ślizgowym

Leus M., Gutowski P., Parus A.

Archiwum Technologii Maszyn i Automatyzacji

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2009

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Vol. 29, nr 4

127-137

PL

W artykule przedstawiono wyniki badań doświadczalnych i analiz symulacyjnych wpływu drgań kontaktowych stycznych wzdłużnych na siłę tarcia i na siłę napędu w ruchu ślizgowym. Stwierdzono, że warunkiem koniecznym zmniejszenia siły napędu niezbędnej do utrzymania ciała w ruchu ślizgowym po podłożu drgającym w kierunku stycznym jest większa amplituda prędkości drgań wzdłużnych niż składowa stała prędkości przesuwu. Badania symulacyjne wykonano w środowisku Matlab/Simulink. W obliczeniach wykorzystano dynamiczne modele tarcia. Badania doświadczalne przeprowadzono na oryginalnym, własnym stanowisku badawczym. Uzyskano bardzo dobrą zgodność wyników badań symulacyjnych i doświadczalnych.

EN

In the paper the results of theoretical and experimental analyses of the longitudinal contact tangential vibration effect on the friction and driving forces in sliding motion are presented. It was observed that the necessary condition for reduction of driving force which was required for maintain a sliding motion on the base excited into vibration, was that the amplitude of velocity of longitudinal tangential vibration should be greater than the constant component of sliding velocity. The simulation analyses were carried out in Matlab/Simulink environment. The experimental tests were performed on the original, made by authors, experimental stand. Very good consistency of simulation and experimental results was obtained.

8

Mechanical systems vibrating longitudinally with the transportation effect

Buchacz A., Żółkiewski S.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 21, nr 1

63-66

EN

Purpose: High work speeds of mechanisms, using materials with high flexibility, high precision of work, etc. are the cause of searching of the new ways of modelling. One of these ways is presented in this thesis. The main purpose of this thesis is the dynamical analysis with taking into consideration the interaction between main motion and local vibrations during the model is loaded by longitudinal forces. Design/methodology/approach: Derived equations of motion were made by classical methods, with generalized coordinates and generalized velocities assumed as orthogonal projections of individual coordinates and velocities of the rod and manipulators to axes of the global inertial frame. Findings: Mathematical model of the longitudinally vibrating systems in terms of plane motion can be put to use to derivation of the dynamical flexibility of these systems, and also those equations are the starting point to the analysis of complex systems, especially we can use those equations to derivation of the substitute dynamical flexibility of n-linked systems in transportation. Research limitations/implications: In the thesis were considered mechanical systems vibrating longitudinally in terms of rotation. Next problem of dynamical analysis is the analysis of systems in non-planar transportation and systems loaded by transversal forces. Practical implications: Results of this thesis can be put to use into machines and mechanisms in transportation such as: wind power plant, high speed turbines, rotors, manipulators and in aerodynamics issues, etc. Originality/value: Up to now there were analyzed beams and rods in a separate way, first main motion of the system and after that the local vibrations. The new approach of modelling were presented by authors of this thesis, a new modelling took into consideration the interaction between those two displacements. There was defined the transportation effect for models vibrating longitudinally in this thesis.

9

Longitudinal vibrations of an elastically connected double-rod complex system. Part I, Free vibrations

Oniszczuk Z.

Vibrations in Physical Systems

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2006

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Vol. 22

291--296

10

Wykorzystanie parametrów drgań wzdłużnych tulei cylindrowych w diagnostyce okrętowych tłokowych silników spalinowych

Witkowski K.

Diagnostyka

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2005

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Vol. 35

137--144

PL

W artykule przedstawiono wyniki badań wstępnych dotyczących możliwości wykorzystania w diagnostyce okrętowych silników tłokowych drgań wzdłużnych tulei cylindrowej. Wyniki badań wykazały, że ten sygnał wibroakustyczny może być przydatny do wykrywania stanów przedzatarciowych układu tłok-cylinder.

EN

In the paper the preliminary research results at the possibilities at using cylinder liner longitudinal vibrations in marine diesel engine diagnostics has been presented. The research results have proven that these vibroacoustics signal can be useful to defect the prefrictional states of piston-cylinder liner system.

11

Diagnozowanie ułożenia wału korbowego maszyn okrętowych.

Bielawski P.

Zagadnienia Eksploatacji Maszyn

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2002

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Vol. 37, nr 4

177-193

PL

Scharakteryzowano naprężenia gnące w wałach korbowych i podano przyczyny zmian naprężeń podczas eksploatacji maszyny. Opisano sprężynowanie wykorbień jako miarę ułożenia wału. Przedstawiono związki między sprężynowaniem wykorbień a przemieszczeniem poosiowym wolnego końca wału. Wskazano na możliwość wykorzystania drgań wzdłużnych wału korbowego maszyny w diagnozowaniu ułożenia wału i przedstawiono przydatne miary drgań.

EN

Essential characteristic features of marine machinery have been mentioned: large dimensions and weight, high and very high power or capacity, long life and effects of a breakdown resulting in high costs of troubleshooting, danger to health and life and the loss of ship's manoeuvring capabilities. One of the main groups of causes resulting in a breakdown are those causing additional bending stresses in crankshafts which add up to working stresses. It is necessary to create tools for detecting the stresses and to modify the forecasting algorithm so that it takes into account the time of crankshaft damage. Causes of bending stresses in a crankshaft are given; besides, the fact has been emphasised that the crankshaft deflection is a static measure of crankshaft position. Relations are shown between additional load of main crankshaft bearings, crankshaft deflection and stresses in the crankshaft. The notion of longitudinal displacement of the free pin of the crank fastened on one end only is introduced. A geometric method of describing the dependence of free crank displacement on the value of crank deflection in vertical and horizontal planes, and on positive and negative deflection. The theoretical decomposition of the crankshaft into one-end fastened cranks was applied in order to determine the resultant displacement of the last main crankpin (free end of the crankshaft) of one-end fastened crankshaft. The created model assumes that the longitudinal displacement of the crankshaft free end is the geometric sum of the displacements of non-fastened pins of individual cranks. The measures given, crankshaft-position oriented, are those of crankshaft free end displacement as the function of shaft turning angle. It is assumed that longitudinal vibrations of the free crankshaft end measured as the function of turning angle include crankshaft position oriented components. The following magnitudes are taken as crankshaft position oriented measures of longitudinal vibrations: mean and peak values as well as phase shift of the first harmonic of those vibrations. The created model, presenting the relations between the longitudinal displacement of the free end and crankshaft displacement given as the deflections of individual cranks, has been verified experimentally. A linear relationship is indicated between the crankshaft free end displacement calculated from the measured deflection and the displacement measured at slow revolving crankshaft of an engine. It has been proved that the longitudinal vibrations depend on both crankshaft deflection and the loads on individual engine cylinders. Presented is a concept of longitudinal vibrations reduction to the vibrations occuring at the nominal load and uniform load of all cylinders.