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Research on stability and sensitivity of the rotating machines with overhung rotors to lateral vibrations

Szolc Tomasz, Konowrocki Robert

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e137987

EN

The rotating machines with overhung rotors form a broad class of devices used in many types of industry. For this kind of rotor machine in the paper, there is investigated an inf luence of dynamic and static unbalance of a rotor, parallel and angular misalignments of shafts, and inner anisotropy of rigid couplings on system dynamic responses. The considerations are performed through a hybrid structural model of the machine rotor-shaft system, consisting of continuous beam finite elements and discrete oscillators. Numerical calculations are carried out for parameters characterizing a heavy blower applied in the mining industry. The main goal of the research is to assess the sensitivity of the imperfections mentioned above on excitation severity of rotor-shaft lateral vibrations and motion stability of the machine in question.

2

Transverse vibration analysis of nonlocal beams with various slenderness ratios, undergoing thermal stress

Babaei Alireza, Rahmani Arash, Ahmadi Isa

Archive of Mechanical Engineering

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2019

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Vol. LXVI, nr 1

5--24

EN

In this paper, thermally-excited, lateral free vibration analysis of a small-sized Euler-Bernoulli beam is studied based on the nonlocal theory. Nonlocal effect is exerted into analysis utilizing differential constitutive model of Eringen. This model is suitable for design of sensors and actuators in dimensions of micron and submicron. Sudden temperature rise conducted through the thickness direction of the beam causes thermal stresses and makes thermo-mechanical properties to vary. This temperature field is supposed to be constant in the lateral direction. Temperatures of the top and bottom surfaces of the system are considered to be equal to each other. Governing equation of motion is derived using Hamilton’s principle. Numerical analysis of the system is performed by Galerkin’s approach. For verification of the present results, comparison between the obtained results and those of benchmark is reported. Numerical results demonstrate that dynamic behavior of small-sized system is been effected by temperature shift, nonlocal parameter, and slenderness ratio. As a result, taking the mentioned parameters into account leads to better and more reliable design in miniaturized-based industries.

3

Modeling and Analysis of Lateral Vibrations of the Forest Crane Boom

Cekus D., Posiadała B., Waryś P.

Machine Dynamics Research

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2010

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Vol. 34, No. 3

38-46

EN

In this paper the analysis of vibrations on the basis of two computational models of the crane: the simulating model, worked out with help of the finite elements method (FEM) and the modal model which is the result of the experimental modal analysis conducted on the real object have been presented. The carried out research concern the vibrations of the system in the lifting and rotary plane of the boom. Researchers have been performed by fixed configuration of the system, reflecting the crane position while the load is picked from the foundation. Frequencies and the mode shapes obtained from simulating research have been compared with the results of the experimental modal analysis. The simulation FEM model represents properly the dynamical properties of the real forest crane and it can be used to investigate the dynamic behaviour of the real object in any other than presented in the work cases of working configurations.

4

Active vibration reduction of rigid rotor supported by journal bearings

Ondrouch J., Ferfecki P, Poruba Z

Modelling and Optimization of Physical Systems

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2009

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z. 8

85--90

EN

The contribution describes the possibilities of active reduction of lateral vibration of symmetric, rigid rotor supported by journal bearings on the base of computational modelling. The efficiency of the feedback P, PD and PID controllers in stable revolution area is examined. To do it the linearized rotor system model is used. The results of the theoretical analysis will be used for the testing stand where the bearing shells motions are controlled by the piezoelectric actuators connected with controllers.

CS

Článek se zabývá možnostmi aktivního snížení příčného kmitání symetrického, dokonale tuhého rotoru uloženého na hydrodynamických ložiskách, na základě počítačového modelování. Je zkoumána účinnost zpětné vazby s regulátory P, PD a PID ve stabilní otáčkové oblasti. Κ tomu je využit linearizovaný model rotorové soustavy. Výsledky teoretické analýzy budou využily u zkušebního stavu, u kterého jsou pohyby ložiskových pouzder ovládány pomocí piezoaktuátorů napojených na regulátory.

5

Srovnání dvou přístupů pro výpočet příčného kmitání rotoru s uvážením rázů kotoučů na stacionární část data

Obruča Z.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2002

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z. 19

113-118

EN

This contribution deals with analysis of lateral vibration of a rotor taking into account impacts of the discs on the stationary part. The shaft was represented by a beam-like body that was discretized into finite elements. For solving the equation of motion an implicit Newmark method has been chosen and modified for the purpose of the calculation. In the paper there are compared two approaches to incorporation of components of the contact force into the equation of motion.

6

Lateral-torsional vibration analysis of the rotor-shaftbearing system using various mechanical models

Kiciński J., Rządkowski R., Szolc T., Walczyk Z.

Vibrations in Physical Systems

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2002

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Vol. 20

180--181