Assoc. Prof. Tomasz Szolc, Ph.D., Dr. Habil., Eng.

Department of Intelligent Technologies (ZTI)
Division of Control and System Dynamics (PSiDU)
position: professor IPPT
telephone: (+48) 22 826 12 81 ext.: 319
room: 436
e-mail: tszolc

Doctoral thesis
1986Modelowanie układów korbowych spalinowych silników tłokowych z wykorzystaniem skrętnych fal sprężystych 
supervisor -- Prof. Władysław Nadolski, Ph.D., Dr. Habil., Eng., IPPT PAN
427 
Habilitation thesis
2004-11-25Analiza dynamiczna złożonych, dyskretno-ciągłych układów mechanicznych912
 
Supervision of doctoral theses
1.2013-06-05Pręgowska Agnieszka  Półaktywne sterowanie układami mechanicznymi drgającymi skrętnie661
 

Recent publications
1.Michajłow M., Jankowski Ł., Szolc T., Konowrocki R., Semi-active reduction of vibrations in the mechanical system driven by an electric motor, OPTIMAL CONTROL APPLICATIONS & METHODS, ISSN: 0143-2087, DOI: 10.1002/oca.2297, pp.1-12, 2017
Abstract:

In this paper, a semi-active damping approach is used for reduction of vibrations in a laboratory drivetrain system. The considered drivetrain system is powered by an electric, asynchronous motor at the one side and loaded with a harmonically varying torque on the other side. Here, an influence of electromechanical interaction, i.e., an electromechanical coupling, between the electric motor and the mechanical system has been taken into consideration. The harmonic load signal induces torsional vibrations in the system, which in the steady-state phase of motion become periodic. The aim of the work is to determine the optimal control function for a semi-active damping element, leading to vibration reduction and considering only the steady-state phase of system motion. The optimal control is derived by using a semi-analytical approach based on the optimal control theory aided with supplementary numerical computations. The proposed methodology is fully general, and it can be directly applied to any type of a periodically oscillating system.

Keywords:

electric motor, electromechanical coupling, optimal control, periodic torsional vibrations, semi-active damping

Affiliations:
Michajłow M.-IPPT PAN
Jankowski Ł.-IPPT PAN
Szolc T.-IPPT PAN
Konowrocki R.-IPPT PAN
2.Konowrocki R., Szolc T., Pochanke A., Pręgowska A., An influence of the stepping motor control and friction models on precise positioning of the complex mechanical system, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2015.09.030, Vol.70-71, pp.397-413, 2016
Abstract:

This paper aims to investigate, both experimentally and theoretically, the electromechanical dynamic interaction between a driving stepping motor and a driven laboratory belt-transporter system. A test-rig imitates the operation of a robotic device in the form of a working tool-carrier under translational motion. The object under consideration is equipped with measurement systems, which enable the registration of electrical and mechanical quantities. Analytical considerations are performed by means of a circuit model of the electric motor and a discrete, non-linear model of the mechanical system. Various scenarios of the working tool-carrier motion and positioning by the belt-transporter are measured and simulated; in all cases the electric current control of the driving motor has been applied. The main goal of this study is to investigate the influence of the stepping motor control parameters along with various mechanical friction models on the precise positioning of a laboratory robotic device.

Keywords:

Belt transporter system, Precise positioning, Stepping motor, Current control, Experimental verification

Affiliations:
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
Pochanke A.-other affiliation
Pręgowska A.-IPPT PAN
3.Konowrocki R., Szolc T., An analysis of the self-excited torsional vibrations of the electromechanical drive system, VIBRATIONS IN PHYSICAL SYSTEMS, ISSN: 0860-6897, Vol.27, pp.187-194, 2016
Abstract:

This paper presents a dynamic analysis of torsional vibrations of the railway drive system. A dynamic electromechanical drive model has been created and then integrated with the railway wheelset-rail system to simulate self-excited torsional vibrations of the considered system. Results of this analysis are used in order to investigate the drive system’s sensitivity to torsional oscillations. Here, the dynamic electromechanical interaction between the electric driving motor and the rotating wheelset is considered. This investigation has proved that the torsional stiffness and damping of drivetrain system strongly affect amplitudes of the self-excited vibrations. A self-excited vibrations affecting on an energy consumption of the electric motor of the considered system are studied.

Keywords:

torsional vibrations, electromechanical coupling, wheel-rail adhesion, wheelset drivetrain dynamic

Affiliations:
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
4.Michajłow M., Konowrocki R., Szolc T., A semi-active control of lateral vibrations of the overhung rotor using dampers with the magneto-rheological fluid, VIBRATIONS IN PHYSICAL SYSTEMS, ISSN: 0860-6897, Vol.27, pp.274-280, 2016
Abstract:

In the paper there is proposed an algorithm of an efficient semi-active control of steady-state periodic lateral vibrations of the overhung rotor-shaft system. This algorithm has been developed using fundamentals of the Optimal Control Theory. In the considered system the control is realized by means of the linear dampers withthe magneto-rheological fluid built in the bearing housing. The computational example demonstrates possibilities of the applied approach resulting in an additional reduction of out-of-resonance and near resonance harmonic oscillation amplitudes in comparison withan analogous passive control.

Keywords:

overhung rotor-shaft, lateral vibrations, semi-active control, Optimal Control Theory

Affiliations:
Michajłow M.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
5.Michajłow M., Szolc T., Jankowski Ł., Konowrocki R., Semi-Active Reduction of Vibrations of Periodically Oscillating System, Solid State Phenomena, ISSN: 1662-9779, DOI: 10.4028/www.scientific.net/SSP.248.111, Vol.248, pp.111-118, 2016
Abstract:

Periodical vibrations are common phenomenon affecting a wide range of mechanical systems. Most frequently it affects machines designed to work in a steady-state conditions like: turbine, pump, rail vehicle, etc. In those kinds of machines it is always possible to decompose the system motion to basic average-speed constant component and oscillatory component. Usually the second term is treated as undesirable and various techniques are applied in order to minimize it as far as it is possible. These techniques refers to both the hardware selection – meaning the type of damping system (active, semi-active, passive) and the control method selection – meaning the damping system control method. Concerning the control methods, there are many algorithms available in literature devoted to transient systems. One of typical application is to use them in systems experiencing sudden, external force excitation. After destabilization of the system, caused by excitation, the role of the control algorithm is to restore the system stable position and additionally to reach the extreme of some additional criterion. Typical criterions are minimization of the time, of restoring the stable position, minimizing the consumed control energy, etc. On the other hand, considering the steady-state systems, especially based on semi-active damping elements, there are not so many control methods available.This paper focuses on developing the proper methodology for deriving the optimal control strategy of semi-active damping element, to be used in periodically vibrating mechanical system. The control strategy is developed on the basis of the Optimal Control Theory. Numerical computations are involved in order to solve the optimal control problem for the considered test system. Problem solution reveals the periodical nature of optimal control function.

Keywords:

Optimal Control Theory, Periodical Vibrations, Vibration Reduction

Affiliations:
Michajłow M.-IPPT PAN
Szolc T.-IPPT PAN
Jankowski Ł.-IPPT PAN
Konowrocki R.-IPPT PAN
6.Konowrocki R., Pręgowska A., Szolc T., Experimental and numerical investigations for the controlled rotary damper dynamically interacting with the electromechanical rotating system, SOLID STATE PHENOMENA, ISSN: 1012-0394, DOI: 10.4028/www.scientific.net/SSP.240.198, Vol.240, pp.198-205, 2016
Abstract:

In the paper dynamic electromechanical coupling between the structural model of the rotating machine drive system and the circuit model of the asynchronous motor has been investigated. By means of the computer model of the rotating machine drive system the results of experimental testing have been confirmed. From the obtained results of computations and measurements it follows that the coupling between the considered rotating system and the installed rotary dampers with the magneto-rheological fluid (MRF) results in effective energy dissipation leading to significant reduction of undesired torsional vibrations.

Keywords:

Electromechanical Coupling, Machine Drive Systems, Rotary MRF Actuator, Torsional Vibrations, Wavelet Transform (WT)

Affiliations:
Konowrocki R.-IPPT PAN
Pręgowska A.-IPPT PAN
Szolc T.-IPPT PAN
7.Lasota R., Stocki R., Tauzowski P., Szolc T., Polynomial chaos expansion method in estimating probability distribution of rotor-shaft dynamic responses, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: 10.1515/bpasts-2015-0047, Vol.63, No.2, pp.413-422, 2015
Abstract:

The main purpose of the study is an assessment of computational efficiency of selected numerical methods for estimation of vibrational response statistics of a large multi-bearing turbo-generator rotor-shaft system. The effective estimation of the probability distribution of structural responses is essential for robust design optimization and reliability analysis of such systems. The analyzed scatter of responses is caused by random residual unbalances as well as random stiffness and damping parameters of the journal bearings. A proper representation of these uncertain parameters leads to multidimensional stochastic models. Three estimation techniques are compared: Monte Carlo sampling, Latin hypercube sampling and the sparse polynomial chaos expansion method. Based on the estimated values of the first four statistical moments the probability density function of the maximal vibration amplitude is evaluated by the maximal entropy principle method. The method is inherently suited for an accurate representation of the probability density functions with an exponential behavior, which appears to be characteristic for the investigated rotor-shaft responses. Performing multiple numerical tests for a range of sample sizes it was found that the sparse polynomial chaos method provides the best balance between the accuracy and computational effectiveness in estimating the unknown probability distribution of the maximal vibration amplitude.

Keywords:

stochastic moment estimation, sparse polynomial chaos expansion, maximum entropy principle, rotor, uncertainties, hybrid mechanical model, random unbalance distribution

Affiliations:
Lasota R.-IPPT PAN
Stocki R.-other affiliation
Tauzowski P.-IPPT PAN
Szolc T.-IPPT PAN
8.Szolc T., Konowrocki R., Michajłow M., Pręgowska A., An investigation of the dynamic electromechanical coupling effects in machine drive systems driven by asynchronous motors, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2014.04.004, Vol.49, pp.118-134, 2014
Abstract:

In the paper dynamic electromechanical interaction between the rotating machine drive system and the electric driving motor is considered. The investigations are performed by means of the circuit model of the asynchronous motor as well as using an advanced structural hybrid model of the drive system. Using the analytical solutions applied for the electrical and the mechanical systems the electromagnetic stiffness and coefficient of damping, both generated by the electric motor rotationally interacting with the mechanical system of the given dynamic properties, were determined. By means of experimentally validated computational responses obtained for torsional harmonic excitation induced by the driven machine working tool, a modification of dynamic properties of the mechanical system by the electromagnetic flux between the stator and the rotor has been studied.

Keywords:

Machine drive system, Asynchronous motor, Electromechanical coupling

Affiliations:
Szolc T.-IPPT PAN
Konowrocki R.-IPPT PAN
Michajłow M.-IPPT PAN
Pręgowska A.-IPPT PAN
9.Szolc T., Kowalewski Z.L., An application of longitudinal elastic waves for investigation of materials under high strain rates using the Hopkinson bar, VIBRATIONS IN PHYSICAL SYSTEMS, ISSN: 0860-6897, Vol.26, pp.305-310, 2014
Abstract:

In the paper there is presented a discrete - continuous model of the Split Hopkinson Pressure Bar (SHPB) for numerical simulations of a dynamic behaviour of material specimens under high strain - rates. For this purpose several material theories describing visco-elasto-plastic properties of the tested specimens can be applied. Using this model impact-type dynamic responses are sought by means of the longitudinal elastic wave analytical solution of the d’Alembert type. The proposed model enables us theoretical strength investigations for various elasto-plastic materials under great deformation velocities as well as structural parameter de termination of the real SHPB designed to play a role of the laboratory test-rig.

Keywords:

Hopkinson bar, elastic wave propagation, d’Alembert solution, numerical simulation

Affiliations:
Szolc T.-IPPT PAN
Kowalewski Z.L.-IPPT PAN
10.Pręgowska A., Konowrocki R., Szolc T., Analysis of rotating systems using actuators with magnetorheological fluid to vibration minimization – theoretical and experimental investigation, Symulacja w Badaniach i Rozwoju, ISSN: 2081-6154, Vol.5, No.3, pp.191-198, 2014
Abstract:

The analysis of damped rotating systems using actuators with magnetorheological fluid is the subject of interest. The main purpose of this research is minimization of vibration amplitudes in order to increase fatigue durability of the most responsible machine elements. Here, control damping torques are generated by magnetorheological fluid of adjustable viscosity.
The theoretical investigations are based on a hybrid and finite element structural model (FEM) of the mechanical structure as well as on sensitivity analysis of the response with respect to the actuators damping characteristics. The analysis performed in the paper combines experimental verification using the laboratory test rig with theoretical computations.

Keywords:

rotating systems, torsional vibrations, actuators with a magnetorheological fluid, rotary actuators

Affiliations:
Pręgowska A.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
11.Pręgowska A., Konowrocki R., Szolc T., On the semi-active control method for torsional vibrations in electro-mechanical systems by means of rotary actuators with a magneto-rheological fluid, JOURNAL OF THEORETICAL AND APPLIED MECHANICS, ISSN: 1429-2955, Vol.51, No.4, pp.979-992, 2013
Abstract:

The aim of this paper is to present a method of the semi-active control of torsional vibrations in a working machine drive system by means of rotary actuators with a magneto-rheological fluid. The simple open-loop control strategy is proposed for a mechanical system vibrating in steady-state operating conditions. This semi-active control approach is based on the principle of optimum viscous damping and frictional properties realized by the magneto-rheological fluid, where its respective parameters are determined by the applied control electric currents. The analysis is performed theoretically by means of structural electro-mechanical models of the considered drive system as well as experimentally using a laboratory test rig in the form of a rotor-shaft system co-operating with two asynchronous motors generating properly programmed driving and retarding electro-magnetic torques

Keywords:

semi-active control, torsional vibrations, magneto-rheological rotary dampers

Affiliations:
Pręgowska A.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
12.Pręgowska A., Konowrocki R., Szolc T., Semi-active vibration control using a rotary magnetorheological damper – experimental verification, POMIARY - AUTOMATYKA - ROBOTYKA. PAR, ISSN: 1427-9126, Vol.2, pp.487-491, 2013
Abstract:

From all kinds of vibrations, torsional ones are very important as naturally associated with fundamental rotational drive system motion. The aim of this paper is to present semi-active control of torsional vibrations of the working machine drive systems, which is performed using a rotary damper with the magnetorheological fluid. The main purpose of this research is vibration amplitudes minimization in order to increase fatigue durability of the most responsible machine elements. The special control strategies are proposed for steady-state torsional vibrations suppression. The semi-active control method is based on a principle of determinational optimum current damping coefficient values, which is realized by the magneto-rheological fluid application. The analysis performed in the paper combines experimental verification using the laboratory test rig with theoretical computations. This experiment was designed in the form of the laboratory drive system co-operating with two asynchronous motors generating properly programmed driving and retarding electromagnetic torques.

Keywords:

semi-active control, torsional vibrations, rotary dampers, magnetorheological fluid, electromechanical drive system

Affiliations:
Pręgowska A.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
13.Stocki R., Szolc T., Tauzowski P., Knabel J., Robust design optimization of the vibrating rotor shaft system subjected to selected dynamic constraints, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, DOI: 10.1016/j.ymssp.2011.07.023, Vol.29, pp.34-44, 2012
Abstract:

The commonly observed nowadays tendency to weight minimization of rotor-shafts of the rotating machinery leads to a decrease of shaft bending rigidity making a risk of dangerous stress concentrations and rubbing effects more probable. Thus, a determination of the optimal balance between reducing the rotor-shaft weight and assuring its admissible bending flexibility is a major goal of this study. The random nature of residual unbalances of the rotor-shaft as well as randomness of journal-bearing stiffness have been taken into account in the framework of robust design optimization. Such a formulation of the optimization problem leads to the optimal design that combines an acceptable structural weight with the robustness with respect to uncertainties of residual unbalances – the main source of bending vibrations causing the rubbing effects. The applied robust optimization technique is based on using Latin hypercubes in scatter analysis of the vibration response. The so-called optimal Latin hypercubes are used as experimental plans for building kriging approximations of the objective and constraint functions. The proposed method has been applied for the optimization of the typical single-span rotor-shaft of the 8-stage centrifugal compressor.

Keywords:

Rotor-shaft system, Robust design optimization, Lateral vibrations, Rubbing effects, Random unbalance distribution

Affiliations:
Stocki R.-IPPT PAN
Szolc T.-IPPT PAN
Tauzowski P.-IPPT PAN
Knabel J.-IPPT PAN
14.Szolc T., Pochanke A., Dynamic investigations of electromechanical coupling effects in the mechanism driven by the stepping motor, JOURNAL OF THEORETICAL AND APPLIED MECHANICS, ISSN: 1429-2955, Vol.50, No.2, pp.653-673, 2012
Abstract:

In the paper, an analysis of transient and steady-state electro-mechanical vibrations of a precise drive system driven by a stepping motor is performed. These theoretical investigations are based on a hybrid structural model of the mechanical system as well as on the classical circuit model of the stepping motor. The main purpose of these studies is to indicate essential differences between the torsional dynamic responses obtained for the considered object regarded respectively as electromechanically coupled and uncoupled. From the computational results, it follows that these differences are qualitatively and quantitatively essential from the viewpoint of possibly precise and reliable operation of the drive systems. Here, torsional vibrations of the drive system significantly influence the electro-mechanical coupling effects, which emphasizes the ir importance in dynamic analyses

Keywords:

electro-mechanical vibrations, drive system, stepping motor,hybrid model

Affiliations:
Szolc T.-IPPT PAN
Pochanke A.-other affiliation
15.Stocki R., Lasota R., Tauzowski P., Szolc T., Scatter assessment of rotating system vibrations due to uncertain residual unbalances and bearing properties, COMPUTER ASSISTED METHODS IN ENGINEERING AND SCIENCE, ISSN: 2299-3649, Vol.19, pp.95-120, 2012
Abstract:

The main objective of the presented study is an evaluation of the effectiveness of various methods for estimating statistics of rotor-shaft vibration responses. The computational effectiveness as well as the accuracy of statistical moment estimation are essential for efficient robust design optimization of the rotor-shaft systems. The compared methods include sampling techniques, the perturbation approach, the dimension reduction method and the polynomial chaos expansion method. For comparison, two problems of the rotor-shaft vibration analysis are considered: a typical single-span rotor-shaft of the 8-stage centrifugal compressor driven by the electric motor and a large multi-bearing rotor-shaft system of the steam turbo-generator. The most important reason for the observed scatter of the rotor-shaft vibration responses is the inherently random nature of residual unbalances as well as stiffness and damping properties of the journal bearings. A proper representation of these uncertain parameters leads to multidimensional stochastic models. It was found that methods that provide a satisfactory balance between the estimation accuracy and computational effectiveness are sampling techniques. On the other hand, methods based on Taylor series expansion in most of the analysed cases fail to approximate the rotor-shaft response statistics.

Keywords:

Scatter analysis, rotor-shaft vibrations

Affiliations:
Stocki R.-IPPT PAN
Lasota R.-IPPT PAN
Tauzowski P.-IPPT PAN
Szolc T.-IPPT PAN
16.Michajłow M., Konowrocki R., Szolc T., Vibration control of the rotating machine geared drive system using linear actuators with the magneto-rheological fluid, VIBRATIONS IN PHYSICAL SYSTEMS, ISSN: 0860-6897, Vol.25, pp.279-284, 2012
Abstract:

In this paper there is proposed a semi-active control technique based on the linear actuators with the magneto-rheological fluid (MRF) connecting the drive system planetary gear housing with the immovable rigid support. Here, control damping torques are generated by means of the magneto-rheological fluid of adjustable viscosity. Such actuators can effectively suppress amplitudes of severe transient and steady-state rotational fluctuations of the gear housing position and in this way they are able to minimize dangerous oscillations of dynamic torques transmitted by successive shaft segments in the entire drive system. The general purpose of the considerations is to control torsional vibrations of the real power-station coal-pulverizer geared drive system driven by means of the asynchronous motor. The investigations have been carried out using the experimental test rig based on the real object, where the measurement results were compared with analogous theoretical ones obtained by the use of computer simulations.

Keywords:

torsional vibrations, magneto-rheological dampers, semi-active control

Affiliations:
Michajłow M.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
17.Pręgowska A., Konowrocki R., Szolc T., Experimental verification of the semi-active control concepts for torsional vibrations of the electro-mechanical system using rotary magneto-rheological actuators, VIBRATIONS IN PHYSICAL SYSTEMS, ISSN: 0860-6897, Vol.25, pp.329-334, 2012
Abstract:

In the paper semi-active control of torsional vibrations of the rotating machine drive system driven by an electric motor is performed by means of rotary actuators with the magneto-rheological fluid. The main purpose of these studies is a minimisation of vibration amplitudes in order to increase the fatigue durability of the most responsible elements, assure possibly precise motion of the driven machine working tool as well as to reduce a generated noise level. For suppression of steady-state torsional vibrations excited by dynamic external torques generated by the motor and by the driven object there are proposed control strategies based on a principle of optimum current damping coefficient values realized by the magneto-rheological fluid. The theoretical control concepts are experimentally verified using the laboratory test rig in the form of drive system co-operating with two asynchronous motors generating properly programmed driving and retarding electromagnetic torques.

Keywords:

semi-active control, torsional vibrations, rotary actuators, magneto-rheological fluid

Affiliations:
Pręgowska A.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
18.Pochanke A., Szolc T., Oddziaływanie elektromechaniczne w systemie napędowym z silnikiem skokowym, PRZEGLĄD ELEKTROTECHNICZNY, ISSN: 0033-2097, Vol.87, No.11, pp.64-67, 2011
Abstract:

W pracy przedstawiono model matematyczny do badania dynamicznego oddziaływania między częściami elektromechanicznymi w systemie napędowym z hybrydowym silnikiem skokowym. W przypadku takiego systemu musi być zapewniony precyzyjny ruch obrotowy, dlatego już w procesie projektowania trzeba przewidzieć i uwzględnić efekt sprzężenia elektromechanicznego, a można to uczynić jedynie z wykorzystaniem dostatecznie dokładnych modeli matematycznych układu mechanicznego i silnika napędowego. Z przeprowadzonych obliczeń symulacyjnych wynika, że wpływ oddziaływania elektromechanicznego na właściwości systemu napędowego z silnikiem skokowym może być znaczne.

Keywords:

układ napędowy, silnik skokowy, oddziaływanie elektromechaniczne, modele matematyczne

Affiliations:
Pochanke A.-other affiliation
Szolc T.-IPPT PAN
19.Szolc T., Pochanke A., Transient and steady-state coupled elektro-mechanical vibration analysis of the micro-drive system, VIBRATIONS IN PHYSICAL SYSTEMS, ISSN: 0860-6897, Vol.24, pp.411-416, 2010
Abstract:

In the paper there is performed an analysis of transient and steady-state electro-mechanical vibration s of the laboratory micro-drive system driven by the stepping motor. The main purpose of these studies is to indicate significant differences between the dynamic responses obtained for the considered object regarded respectively as electro-mechanically coupled and uncoupled. These theoretical investigations are based on a hybrid structural model of the mechanical system as well as on the classical circuit model of the stepping motor. From the computational results it follows that these differences are qualitatively and quantitatively essential from the viewpoint of possibly precise and reliable operation of the micro-drive systems.

Keywords:

Transient coupled elektromechanical, vibration analysis, micro-drive system

Affiliations:
Szolc T.-IPPT PAN
Pochanke A.-other affiliation
20.Szolc T., Tauzowski P., Stocki R., Knabel J., Damage identification in vibrating rotor-shaft systems by efficient sampling approach, MECHANICAL SYSTEMS AND SIGNAL PROCESSING, ISSN: 0888-3270, Vol.23, pp.1615-1633, 2009
Abstract:

In the paper a stochastic method for fault detection and identification in the shafts of rotating machines is proposed. This approach is based on the Monte Carlo simulations of rotor-shaft lateral–torsional–longitudinal vibrations mutually coupled by transverse cracks of various possible and randomly selected depths and locations on the shaft. For this purpose the structural hybrid model of a real faulty object is applied. This model is characterized by a high practical reliability and great computational efficiency, so important for many hundred thousand single numerical simulations necessary for a creation of the databases applied for inverse problem solution finally leading to crack identification. These databases are created with an arbitrary assumed probability densities of crack parameters which ensures appropriate spread of the dynamic responses of the considered faulty mechanical system. A sufficiently large database determined for the investigated object enable us to estimate almost immediately, i.e. within less than 1 s, the crack depth and axial position with identification errors not exceeding 9% and 5%, respectively. Thus, the proposed method seems to be a very convenient diagnostic tool for engineering applications in the industry.

Keywords:

Rotor-shaft system, Dynamic diagnostics, Crack identification, Monte Carlo simulation, Coupled vibration analysis

Affiliations:
Szolc T.-IPPT PAN
Tauzowski P.-IPPT PAN
Stocki R.-IPPT PAN
Knabel J.-IPPT PAN
21.Szolc T., Tauzowski P., Knabel J., Stocki R., Nonlinear and parametric coupled vibrations of the rotor-shaft system as fault identification symptom using stochastic methods, NONLINEAR DYNAMICS, ISSN: 0924-090X, Vol.57, pp.533-557, 2009
Abstract:

In the paper several stochastic methods for detection and identification of cracks in the shafts of rotating machines are proposed. All these methods are based on the Monte Carlo simulations of the rotor-shaft lateral-torsional-longitudinal vibrations mutually coupled by transverse cracks of randomly selected depths and locations on the shaft. For this purpose there is applied a structural hybrid model of a real cracked rotor-shaft. This model is characterized by a high practical reliability and great computational effi-ciency, so important for hundreds of thousands numerical simulations necessary to build databases used in solving the inverse problem, i.e. crack parameter identifications. In order to ensure a good identification accuracy, for creating the Monte Carlo samples of data points there are proposed special probability density functions for locations and depths of the crack. Such an approach helps in enhancing databases corresponding to the most probable faults of the rotor-shaft system of the considered rotor machine. In the presentedstudy six different database sizes are considered to compare identification efficiency and accuracy of considered methods. A sufficiently large database enables us to estimate almost immediately (usually in less than one second) the crack parameters with precision that is in most of the cases acceptable in practice. Then, as a next stage, one of the proposed fast improvement algorithms can be applied to refine identification results in a reasonable time. The proposed methods seem to provide very convenient diagnostic tools for industrial applications.

Keywords:

Crack rotor dynamics, Nonlinear and parametric vibrations, Hybrid modeling, Monte Carlo simulation, Crack identification methods

Affiliations:
Szolc T.-IPPT PAN
Tauzowski P.-IPPT PAN
Knabel J.-IPPT PAN
Stocki R.-IPPT PAN
22.Bednarek T., Sosnowski W., Szolc T., Elasto-plastic material model with damage parameter in metal fatigue, COMPUTER METHODS IN MATERIALS SCIENCE / INFORMATYKA W TECHNOLOGII MATERIAŁÓW, ISSN: 1641-8581, Vol.9, No.4, pp.208-210, 2009
Abstract:

In this paper the numerical method for prediction of fatigue life of structure is presented. The fmite element model-ling and damage parameter calculation are based on the algorithm de-scribed originally by Chaboche (1987), Luccioni et al. (1996) and 011er et al. (2005). This al-gorithm is simplified, i.e. the Goodman relationships between the mean and stress amplitude are included. It is extended and applied for simulation of crack propagation in the rotor shaft. The mate-rial constitutive model includes plastic effects and damage. The S—N fatigue func-tions taken from experiment are modi-fied so as to be dependent on the real ratio between minimum and maximum stress in the critical zones. So the coupling between damage, plastic-ity and fatigue is taken into account.

Keywords:

metal fatigue, damage mechanics

Affiliations:
Bednarek T.-IPPT PAN
Sosnowski W.-IPPT PAN
Szolc T.-IPPT PAN
23.Szolc T., Jankowski Ł., Active control of transient torsional vibrations due to run-up of a rotor machine driven by the electric motor, VIBRATIONS IN PHYSICAL SYSTEMS, ISSN: 0860-6897, Vol.23, pp.341-346, 2008
Abstract:

In the paper active control of transient torsional vibrations induced by the electric motor during run-ups of the radial compressor drive system is performed by means of couplings with the magneto-rheological fluid. The main purpose of these studies is a minimisation of vibration amplitudes in order to increase the fatigue durability of the most responsible elements. The theoretical investigations are based on a hybrid structural model of the vibrating mechanical system and sensitivity analysis of the response with respect to the damping characteristics of the control couplings.

Keywords:

active control, transient vibrations, drive system, electric motor

Affiliations:
Szolc T.-IPPT PAN
Jankowski Ł.-IPPT PAN
24.Szolc T., Continuous elastic macro-elements as a natural alternative crack detection tool to the spectral finite element method, ARCHIVES OF MECHANICS, ISSN: 0373-2029, Vol.59, pp.365-391, 2007
Abstract:

IN THE PAPER the wave method of fault identification in rods, shafts and beams is proposed. This method is based on dynamical models consisting of structural macro-elements with continuously distributed inertial-visco-elastic properties, represented by individual segments of the investigated objects. The fault detection and identifi-cation reduces to simulations of diagnostic wave propagation and wave reflections in these models. These simulations are performed directly in time domain by means of analytical solutions of the partial differential equations of motion. In the computa-tional examples, reflected waves were sought in the cracked cantilever rod and beam. These results have been compared with the analogous findings obtained by other au-thors, using the spectral finite element method. The natural continuous character of the applied elastic macro-elements enables us to apply a straightforward simulation of wave effects, which makes the proposed approach a promising and effective tool for fault identification in various structure and mechanical systems.

Keywords:

Continuous elastic macroelements, crack detection, spectral finite element method

Affiliations:
Szolc T.-IPPT PAN
25.Szolc T., Sosnowski W., On partial hydrodynamic lubrication effects in the journal bearings, COMPUTER METHODS IN MATERIALS SCIENCE / INFORMATYKA W TECHNOLOGII MATERIAŁÓW, ISSN: 1641-8581, Vol.7, No.1, pp.94-100, 2007
Abstract:

The objective of this research is to include mixed friction effects into existing models of hydrodynamic journal bearings described e.g. in [1]. The problem of partial hydrodynamic lubrication caused by roughness of sliding surfaces has been investigated for many years by numerous researchers. But majority of theoretical studies in this field were focused on very fundamental aspects taking into consideration general principles of bearing operation from the viewpoint of flow determination between sliding surfaces of various roughness description. The considerations in this paper are devoted to partial hydrodynamic lubrication effects in typical cylindrical transverse journal bearings applied for supporting of heavy rotor-shafts of the rotating machines. For this purpose there is used the average flow theory for an oil film interaction with rough journals and bushings. In order to carry out a qualitative analysis of the problem a simple mechanical model of the partially lubricated “super-bearing” is assumed. This model consists of the rigid mass rotating with constant speed and performing translational in-plane motion within the non-rotating rigid ring which is elastically suspended in this plane. The rigid mass represents the entire inertia of the rotating parts of the rotor machine and the rigid ring corresponds to the housing of such “super bearing”. Translational in-plane motion of the rigid mass is coupled with translational motion of the rigid ring by means of mass-less springs and dampers representing respectively visco-elastic properties of the oil film in the “super-bearing” with rough sliding surfaces. These visco-elastic properties of the oil film in such bearing are determined by numerical solving of the average Reynolds equation describing partial oil flow between the rough journal and bushing. Here, according to, the pressure flow factors and the shear flow factors standing in the average Reynolds equations are determined analytically using proper empirical formulae obtained by numerical simulations of the model flows between partially lubricated surfaces for various roughness geometry and average oil film thicknesses. Solving in this way the average Reynolds equation for the entire oil gap by means of the finite difference method enables us to determine resultant viscous friction retarding force as well as transverse hydrodynamic load of the bearing. For various roughness geometry the former enables us to determine the frictional power yielded by the bearing and the latter makes possible calculation of stiffness and damping coefficients of the mass-less springs representing visco-elastic properties of the oil film in the assumed model of the “super-bearing”. In the numerical examples numerous roughness amplitudes of the journal and the bushing surface as well as various directional orientations of roughness asperities, which follow from final machining of the journal and the bushing, are taken into consideration in order to investigate their influence on kineto-static and dynamic behaviour of the transverse oil-film bearing. In the next steps of research in this field, beyond the partial lubrication, also the metal-to-metal friction effects are going to be investigated, i.e. for so high loadings of the journal bearing, when the hydrodynamic lubrication theory for the oil film stops to be in force

Keywords:

partial hydrodynamic lubrication, journal bearings, mixed friction effects

Affiliations:
Szolc T.-IPPT PAN
Sosnowski W.-IPPT PAN
26.Szolc T., On dynamic interaction between the runway and the aircraft landing gear using the analytical approach, Machine Dynamics Research, ISSN: 2080-9948, Vol.30, pp.73-96, 2006
Abstract:

High static and dynamic overloads caused by the aircraft landing gears moving on the airport runways are a source of uncontrolled cracking of the runway upper layers. In order to investigate this problem the proper analytical model of the runway under moving load is proposed. The finite distance of the runway upper layer is represented by the rectangular continuous Kirchhoff's plate resting on the visco-elastic foundation playing a role of dynamic interface with the runway supporting layer. The plate heterogeneity caused by the runway transverse notches has been taken into consideration in the form of fictitious external response-dependent elastic bending moments. The initial deflections of the runway upper layer due to thermal forces are induced in the model by the equivalent mechanical loads imposed to the plate. Excitation of the plate due to the aircraft landing-gear is represented by the set of moving non-inertial forces, mutual spacing and number of which correspond respectively to the structure and the total number of wheels of the real landing-gear of the assumed aircraft. Numerical simulation of dynamic interaction between the runway and the aircraft landing-gear has been performed by means of the modal approach for various running speeds of the heavy aircraft. The quantities of interests are the dynamic transverse deflections of the plate as well as the normal stress in the notch cross-sections.

Keywords:

dynamic overloads, dynamic interaction, runway,aircraft landing gear, analytical approach

Affiliations:
Szolc T.-IPPT PAN
27.Pręgowska A., Konowrocki R., Szolc T., Optimal segmentation of beam and disk structures, Structural optimization, ISSN: 0934-4373, DOI: 10.1007/BF01197041, Vol.11, No.3, pp.252-259, 1996
Abstract:

Large structures are usually composed of elements by properly designed connections. The optimal design solution in such cases should provide optimal size and number of elements together with optimal connection stiffness. The problem is formulated by assuming the element cost to be a nonlinear function of its size and the cost of connection to depend on its stiffness or transmitted forces. The number of elements and the connection stiffness now constitute the design parameters to be determined. A two-level procedure is proposed for determination of the optimal segmentation for beam and plate structures. Several illustrative examples are presented.

Affiliations:
Pręgowska A.-IPPT PAN
Konowrocki R.-IPPT PAN
Szolc T.-IPPT PAN
28.Bogacz R., Irretier H., Szolc T., Transient Vibration Analysis of a continuous Model of a Turbogenerator Rotor Shaft System Using Torsional Elastic Waves, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.53, pp.1-33, 1988

List of chapters in recent monographs
1.
416
Szolc T., Falkowski K., Mechanisms and Machine Science, rozdział: Dynamic analysis of the high-speed flexible rotors supported on the electrodynamic passive magnetic bearings, Springer International Publishing, 21, pp.1489-1500, 2015
2.
438
Pręgowska A., Szolc T., Pochanke A., Konowrocki R., Recent Advances in Automation, Robotics and Measuring Techniques, rozdział: Modeling and dynamic analysis of the precise electromechanical systems driven by the stepping motors, Springer International Publishing, Series: Advances in Intelligent Systems and Computing, 267, Part I, pp.205-215, 2014
3.
161
Szolc T., Knowledge acquisition for hybrid systems of risk assessment and critical machinery diagnosis, rozdział: Fundamentals of hybrid modeling of cracked shafts of rotor machines, Silesian University of Technology (Gliwice), Moczulski W., Ciupke K. (Eds.), pp.137-146, 2008
4.
162
Szolc T., Knowledge acquisition for hybrid systems of risk assessment and critical machinery diagnosis, rozdział: Exemplary responses of the Monte Carlo simulations used for crack diagnostics, Silesian University of Technology (Gliwice), Moczulski W., Ciupke K. (Eds.), pp.147-160, 2008
5.
163
Szolc T., Tauzowski P., Stocki R., Knabel J., Knowledge acquisition for hybrid systems of risk assessment and critical machinery diagnosis, rozdział: Stochastic approach of crack parameters identification of rotor shaft machines be means of Monte Carlo sampling, Silesian University of Technology (Gliwice), Moczulski W., Ciupke K. (Eds.), pp.161-178, 2008
6.
164
Stocki R., Tauzowski P., Knabel J., Szolc T., Knowledge acquisition for hybrid systems of risk assessment and critical machinery diagnosis, rozdział: Identification methods of crack parameters of rotor shaft machines monitored on-line applied to analysis of steam turbogenerator, Silesian University of Technology (Gliwice), Moczulski W., Ciupke K. (Eds.), pp.179-192, 2008
7.
165
Sosnowski W., Szolc T., Bednarek T., Marczewska I., Marczewski A., Knowledge acquisition for hybrid systems of risk assessment and critical machinery diagnosis, rozdział: Attempts of durability assessment of cracked rotor shafts, Silesian University of Technology (Gliwice), Moczulski W., Ciupke K. (Eds.), pp.193-204, 2008

Conference papers
1.Szolc T., Konowrocki R., Pochanke A., Michajłow M., Dynamic aspects of design and maintenance of the rotating machinery applied by the mining industry , MEC-2017, MINERAL ENGINEERING CONFERENCE, 2017-09-20/09-23, Wisła (PL), DOI: 10.1051/e3sconf/201712301010, No.18, 01010, pp.1-10, 2017
Abstract:

In the paper a dynamic behaviour of the selected typical group of rotating machines applied in the mining industry is investigated. These are the beater mills and crushers as well as blowers and compressors, all driven by the asynchronous motors. In particular, there is considered an influence of various types of machine working tool loadings on the system lateral steady-state dynamic responses as well as a mutual torsional electromechanical interaction between the driving motor and the driven machine in transient operational conditions. The theoretical calculations have been performed by means of the advanced structural mechanical models. The conclusions drawn from computational results can be very useful during design phase of these devices as well as helpful for their users during regular maintenance.

Keywords:

mining industry, electromechanic coupling, design and maintenance of mill, torsional vibrations

Affiliations:
Szolc T.-IPPT PAN
Konowrocki R.-IPPT PAN
Pochanke A.-other affiliation
Michajłow M.-IPPT PAN
2.Szolc T., Falkowski K., Henzel M., Kurtyna-Mazurek P., Passive and active stabilization of the electro-dynamic magnetic bearings supporting high-speed rotors, VITM 11, VITM 11 - Vibrations In Rotating Machinery, IMechE, 2016-09-13/09-15, Machester (GB), pp.721-731, 2016
Abstract:

The electrodynamic passive magnetic bearings became now a very promising kind of support for high-speed rotors. Nevertheless, because of skew-symmetrical visco-elastic properties of such bearings, they are sensitive to operational instability. In order to avoid this disadvantage, in the paper there are proposed stabilization concepts reducing to an introduction of a sufficient magnitude of additional external damping into the vibrating rotor-shaft system. This purpose is going to be realized by means of simple and effective passive dampers built in the electrodynamic bearing housings as well as using heteropolar magnetic dampers which realize operational principles of the active magnetic bearing. The theoretical investigations are going to be carried out by means of a structural computer model of the rotor-shaft system, taking into consideration its full geometry and material properties.

Affiliations:
Szolc T.-IPPT PAN
Falkowski K.-Military University of Technology (PL)
Henzel M.-Military University of Technology (PL)
Kurtyna-Mazurek P.-Military University of Technology (PL)
3.Szolc T., Konowrocki R., Michajłow M., On Research and development-aspects of the highly-energetic concept for the copper ore comminution, ICNOP 2015, XI Międzynarodowa Konferencja Przeróbki Rud Metali Nieżelaznych, 2015-05-27/05-29, Trzebieszowice (PL), pp.47-59, 2015
Abstract:

In the paper there will be presented fundamental advantages and problems connected with an application possibility of the highly-energetic, impact-type technique of the copper ore comminution in a comparison with the analogous methods used till present by the ore pro-cessing plants belonging to the company KGI-IM — Polska Miedt S.A. In this aspect the main technical and exploitation requirements expected from the high-speed beater mills for impact-type copper ore comminution in a dry mode shall be considered. In particular, there will be discussed dynamic phenomena associated with an operation of such devices as well as modern computational methods enabling us an expectation of their positive and negative consequences for an operational effectiveness, durability and robustness of the most respon-sible working elements. The mechanical vibrations can be regarded here as one of the most detrimental phenomenon caused by the highly dynamic interaction between the beater-wheel and the comminuted ore. First of all, these are bending and torsional vibrations of the beater.

Keywords:

copper ore highly-energetic comminution, beater mill, dynamic analysis

Affiliations:
Szolc T.-IPPT PAN
Konowrocki R.-IPPT PAN
Michajłow M.-IPPT PAN
4.Rojek J., Graczykowski C., Marijnissen M.J., Szolc T., Marczewska I., Możliwości wykorzystania dyskretnych metod modelowania do symulacji procesów mechanicznego urabiania i przeróbki rud metali, ICNOP 2015, XI Międzynarodowa Konferencja Przeróbki Rud Metali Nieżelaznych, 2015-05-27/05-29, Trzebieszowice (PL), pp.60-67, 2015
Abstract:

Modelowanie i symulacje numeryczne są obecnie nieodłączną częścią projektowania i optymalizacji różnorodnych procesów technologicznych. Zastosowanie metod numerycznych w projektowaniu procesów mechanicznego urabiania i przeróbki rud metali jest w dalszym ciągu stosunkowo niewielkie. Procesy odspajania kawałków skały od calizny i ich rozdrobnienia z zastosowaniem różnego rodzaju maszyn, wiążą się silnie nieciągłymi zjawiskami zniszczenia materiału i są bardzo trudne do modelowania za pomocą standardowych metod numerycznych, takich jak metoda elementów skończonych, opartych na ciągłym sformułowaniu zagadnienia mechaniki ciała stałego. Duże możliwości w zastosowaniu do tych procesów ma intensywnie rozwijana w ostatnich latach metoda elementów dyskretnych, w której materiał jest reprezentowany przez liczny zbiór ziaren, oddziałujących między sobą poprzez siły kontaktu. Model ten w sposób naturalny uwzględnia materiał rozdrobniony. Uwzględnienie wiązań kohezyjnych między ziarnami oraz możliwości ich zrywania umożliwia modelowanie inicjacji i propagacji pęknięć w materiale. W niniejszej pracy zostaną przedstawione możliwości wykorzystania metody elementów dyskretnych do symulacji urabiania skał za pomocą noży stożkowych i dysków oraz do symulacji zachowania się materiału w młynie. Sprzężenie metody elementów dyskretnych z modelem przepływu płynu umożliwi modelowanie zawiesiny pyłowej rozdrabnianego materiału.

Keywords:

modelowanie dyskretne, mechaniczne urabianie, rudy metali

Affiliations:
Rojek J.-IPPT PAN
Graczykowski C.-IPPT PAN
Marijnissen M.J.-IPPT PAN
Szolc T.-IPPT PAN
Marczewska I.-IPPT PAN
5.Konowrocki R., Pochanke A., Pręgowska A., Szolc T., An analysis of precise positioning scenarios of the electromechanical rotating system driven by a stepping motor, SIRM 2015, 11th International Conference on Vibrations in Rotating Machines, 2015-02-23/02-25, Magdeburg (DE), No.ID-40, pp.1-10, 2015
Abstract:

In the paper there is investigated experimentally and theoretically electromechanical dynamic interaction between the driving stepping motor and the driven laboratory belt-transporter system imitating an operation of the robotic device in the form of working tool-carrier under translational motion. The considered object is properly equipped with measurement systems enabling us a registration of studied electrical and mechanical quantities. The analytical considerations are performed by means of the circuit model of the electric motor and of the discrete, non-linear model of the mechanical system. In the investigated examples various scenarios of the working tool-carrier motion and positioning by the belt-transporter are measured and simulated, where in the all cases the electric current control of the driving motor has been applied.

Keywords:

Belt transporter system, Precise positioning, Stepping motor, Current control, Experimental verification

Affiliations:
Konowrocki R.-IPPT PAN
Pochanke A.-other affiliation
Pręgowska A.-IPPT PAN
Szolc T.-IPPT PAN
6.Szolc T., Konowrocki R., Michajłow M., On electromechanical dynamic coupling effects in the semi-actively controlled rotating machine drive system driven by the induction motor, SIRM 2013, 10th International Conference on Vibrations in Rotating Machines, 2013-02-25/02-27, Berlin (DE), No.ID-258, pp.1-10, 2013
Abstract:

In the paper there is studied dynamic electromechanical interaction between the geared drive system of a rotating machine and the driving induction (asynchronous) motor. The investigations are performed by the use of experimental measurements carried out on the real object as well as by means of a theoretical approach using a circuit model of the electric motor in the form of Park’s equations and the advanced drive system hybrid, i.e. discrete-continuous, mechanical model of an identical structure and parameters as the classical preliminarily applied one-dimensional finite element model. The experimental and theoretical considerations are focused on the steady-state operating conditions, where severe torsional vibrations are excited by variable components of the driven machine retarding torque as well as by the electromagnetic torque generated by the induction motor. The qualitative analysis is performed by means of the harmonic balance method applied for Park’s equations and using the modal approach for the experimentally identified mechanical model. In order to minimize torsional vibration amplitudes induced by the electromechanical interaction in the considered system, the semi-active control technique based on actuators with the magneto-rheological fluid has been tested.

Keywords:

electromechanical dynamic coupling, electric motor, torsional vibrations, experimental investigation

Affiliations:
Szolc T.-IPPT PAN
Konowrocki R.-IPPT PAN
Michajłow M.-IPPT PAN
7.Szolc T., Jankowski Ł., Pochanke A., Michajłow M., Vibration control of the coal pulverizer geared drive system using linear actuators with the magneto-rheological fluid, SIRM 2011, 9th International Conference on Vibrations in Rotating Machines, 2011-02-21/02-23, Darmstadt (GE), pp.1-10, 2011
Abstract:

Torsional vibrations are in general rather troublesome to control from the viewpoint of proper control torque generation as well as because of difficulties of imposing the control torques on quickly rotating parts of the drive- or rotor-shaft systems. In this paper there is proposed an active control technique based on the linear actuators with the magneto-rheological fluid (MRF) connecting the drive system planetary gear housing with the immovable rigid support. Here, by means of the magneto-rheological fluid of adjustable viscosity control damping torques are generated. Such actuators can effectively suppress amplitudes of severe transient and steady-state rotational fluctuations of the gear housing position and in this way they are able to minimize dangerous oscillations of dynamic torques transmitted by successive shaft segments in the entire drive system. The general purpose of the considerations is to control torsional vibrations of the power-station coal-pulverizer drive system driven by means of the asynchronous motor and the single stage planetary gear. In the computational examples drive system transient torsional vibrations induced by the electromagnetic motor torques during start-ups as well as steady-state vibrations excited by the variable dynamic retarding torques generated by the coal pulverizer during nominal operation have been significantly attenuated.

Keywords:

Torsional vibrations, rotational fluctuation, magneto-rheological fluid

Affiliations:
Szolc T.-IPPT PAN
Jankowski Ł.-IPPT PAN
Pochanke A.-other affiliation
Michajłow M.-IPPT PAN
8.Stocki R., Szolc T., Tauzowski P., Knabel J., Robust design optimization of the vibrating rotor shaft system subjected to rubbing constraints, IFToMM, 8th International Conference on Rotor Dynamics, 2010-09-12/09-15, Seoul (KR), pp.1022-1029, 2010
Abstract:

The commonly observed nowadays tendency to weight minimization of rotor-shafts of the rotating machinery leads to a decrease of shaft bending rigidity making a risk of dangerous stress concentrations and rubbing effects more probable. Thus, a determination of the optimal balance between reducing the rotor-shaft weight and assuring its admissible bending flexibility is a major goal of this study. The random nature of residual unbalances of the rotor-shaft as well as randomness of journal bearing stiffness have been taken into account in the framework of robust design optimization. Such a formulation of the optimization problem leads to the optimal design that combines an acceptable structural weight with the robustness with respect to uncertainties of residual unbalances, the main source of bending vibrations causing the rubbing effects. The applied robust optimization technique is based on using Latin hypercubes in scatter analysis of the vibration response. The so-called optimal Latin hypercubes are used as experimental plans for building kriging approximations of the objective and constraint functions. The proposed method has been applied for the optimization of the typical single-span rotor-shaft of the 8-stage centrifugal compressor.

Keywords:

Rotor-shaft system, robust design optimization, lateral vibrations, rubbing effects, random unbalance distribution

Affiliations:
Stocki R.-IPPT PAN
Szolc T.-IPPT PAN
Tauzowski P.-IPPT PAN
Knabel J.-IPPT PAN
9.Szolc T., Jankowski Ł., Pochanke A., Magdziak A., An application of the magneto-rheological actuators to torsional vibration control of the rotating electro-mechanical systems, IFToMM, 8th International Conference on Rotor Dynamics, 2010-09-12/09-15, Seoul (KR), pp.488-495, 2010
Abstract:

In the paper control of transient and steady-state torsional vibrations of the driven by the asynchronous motor laboratory drive system of the imitated coal pulverizer is performed by means of actuators with the magneto-rheological fluid. The main purpose of these studies is a minimisation of vibration amplitudes in order to increase the fatigue durability of the most responsible elements. The theoretical investigations are based on a hybrid and finite element structural model of the vibrating mechanical system as well as on sensitivity analysis of the response with respect to the actuator damping characteristics. For suppression of transient torsional vibrations excited by electro-magnetic torques generated by the motor and by the coal pulverizer tool there is proposed a control strategy based on actuators in the form of rotary control dampers.

Keywords:

Semi-active control, torsional vibrations, electro-mechanical drive system, control dampers, magneto-rheological fluid

Affiliations:
Szolc T.-IPPT PAN
Jankowski Ł.-IPPT PAN
Pochanke A.-other affiliation
Magdziak A.-other affiliation
10.Szolc T., Bogacz R., Analysis of the airport runway n excited by motion of heavy aircrafts, XXII Symposium Vibration in Physical Systems, 2006-04-19/04-22, Poznań-Będlewo (PL), pp.343-348, 2006
Abstract:

In the presented paper by means of the continuous model a dynamic interaction between the airport runway and the aircraft landing-gear is considered in order to investigate the controlled cracking process of the initially notched runway plates. For this purpose normal stresses induced by the static and dynamic loads in the runway plate notched areas are going to be determined by means of the continuous mechanical model and analytical mathematical solution of the problem.

Keywords:

dynamic load, analytical mathematical solution, airport runway

Affiliations:
Szolc T.-IPPT PAN
Bogacz R.-IPPT PAN

Conference abstracts
1.Szolc T., Konowrocki R., Pochanke A., Michajłow M., Dynamic aspects of design and maintenance of the rotating machinery applied in the mining industry, MEC-2017, MINERAL ENGINEERING CONFERENCE, 2017-09-20/09-23, Wisła (PL), No.2, pp.14-15, 2017
Abstract:

In the paper a dynamic behaviour of the selected typical group of rotating machines applied in the mining industry is investigated. These are the beater mills and crushers as well as blowers and compressors, all driven by the asynchronous motors. In particular, there is considered an influence of various types of machine working tool loadings on the system lateral steady-state dynamic responses as well as a mutual torsional electromechanical interaction between the driving motor and the driven machine in transient operational conditions. The theoretical calculations have been performed by means of the advanced structural mechanical models. The conclusions drawn from computational results can be very useful during design phase of these devices as well as helpful for their users during regular maintenance.

Keywords:

rotating mill machinery, electric motor interaction, electromechanical model, torsion vibration

Affiliations:
Szolc T.-IPPT PAN
Konowrocki R.-IPPT PAN
Pochanke A.-other affiliation
Michajłow M.-IPPT PAN
2.Stocki R., Lasota R., Tauzowski P., Szolc T., Scatter assessment of rotor-shaft vibration responses due to uncertain residual unbalances and bearing properties, CMM 2011, 19th International Conference on Computer Methods in Mechanics, 2011-05-09/05-12, Warszawa (PL), pp.056-1-2, 2011
Abstract:

The main objective of the presented study is an evaluation of the effectiveness of various methods for estimating statistics of rotor-shaft vibration responses. The computational effectiveness as well as the accuracy of statistical moment estimation are essential for efficient robust design optimization of the rotor-shaft systems. The most important sources of the observed response scatter are inherently random rotor-shaft residual unbalances as well as stiffness and damping properties of the journal bearings. A relevant representation of these parameters leads to multidimensional stochastic models. The compared stochastic moment estimation methods include sampling techniques, the dimension reduction method and the polynomial chaos expansion method. Two problems of the rotor-shaft vibration analysis are considered: a typical single-span rotor-shaft of the 8-stage centrifugal compressor driven by the electric motor and a large multi-bearing rotor-shaft system of the steam turbogenerator. It is shown that methods that provide a satisfactory balance between the estimation accuracy and computational effectiveness are sampling techniques. Methods employing polynomial chaos expansion perform well in the case of reduced stochastic models. On the other hand, low accuracy of the methods based on Taylor series expansion very often renders these techniques unsuitable for the robust design optimization of vibrating rotor shafts.

Keywords:

ibrations, robustness, numerical analysis, stochastic phenomena

Affiliations:
Stocki R.-IPPT PAN
Lasota R.-IPPT PAN
Tauzowski P.-IPPT PAN
Szolc T.-IPPT PAN
3.Szolc T., Bednarek T., Marczewska I., Marczewski A., Sosnowski W., Fatigue analysis of the cracked rotorby means of the one and three dimensional dynamical model, IFToMM, 7th International Conference on Rotor Dynamics, 2006-09-25/09-28, Wiedeń (AT), pp.3-200-00689-7, 2006
Abstract:

In the paper the structural one-dimensional hybrid dynamical model of the entire vibrating rotor-shaft system and the three-dimensional fmite element model of its cracked shaft zone were applied for a fatigue life prediction of the machine faulty segment under coupled bending-torsional-axial vibrations. The steady-state dynamic response amplitudes, obtained by means of the one-dimensional model of the system, have been used for the three-dimensional model as an input data for determination of maximal stresses and stress intensity factors at the crack tip. These quantities together with the Wohler curves enable us an approximate determination of load limits responsible for a probable further crack propagation. By means of the proposed approach one can predict a damage probability of the faulty rotor-shaft system of arbitrary structure operating under various dynamic and quasi-static loads affecting a crack of various sizes and shaft locations. From the investigations performed for various crack axial locations on the shaft with respect to bearing supports of the single- and double-span rotor-shaft systems, it follows that a strength of the cracked zone is much more sensitive to normal stresses due to bending and axial oscillations than to tangential stresses caused by torsional vibrations.

Keywords:

hybrid dynamical mode, vibrating rotor-shaft system, fatigue analysis

Affiliations:
Szolc T.-IPPT PAN
Bednarek T.-IPPT PAN
Marczewska I.-IPPT PAN
Marczewski A.-IPPT PAN
Sosnowski W.-IPPT PAN