Institute of Fundamental Technological Research

Despite the prevalence of well-established and explored navigation systems, alternative localization methods are currently the focus of intensive research. This interest is driven by geopolitical challenges and increasingly sophisticated applications of mobile robots and uncrewed aerial vehicles. This study investigates the problem of real-time positioning in GPS-denied environments. Based on the mapped magnetic anomaly field and using Bayesian formalism for data fusion, the localization obtained from embedded sensors is corrected to reduce cumulative errors. The proposed method has minimal computational cost and a minimal number of tunable parameters. The paper introduces it and demonstrates its effectiveness in a laboratory study. Experimental tests, using a system equipped with an Inertial Measurement Unit, demonstrated a significant reduction in localization uncertainty. The improvement was especially notable in areas with large, smooth variations in the magnetic field. Finally, the accuracy of the method is analyzed, and its performance is compared to a particle filter.

Sensor fusion, Bayesian inference, Real-time positioning, Magnetic anomaly, Intelligent navigation system

This paper presents the results of experimental and numerical studies on reliability and monitoring issues of railway infrastructure in terms of safety and operation. The state of knowledge concerning methods of assessing track condition, in particular rail joints used in continuous welded rail track of railway lines is described. Experimental results of rail joints used in track transition zones and the results of numerical studies/tests of the rail vehicle-track model are outlined. It is demonstrated, basing on the analyses of the experimental results, that not only should the rail joints used in continuous welded rail track be diagnosed during their acceptance, but also during their operation. It is proven that the currently used methodology for testing welded rail joints applied during acceptance testing of contact track is not fully correct and leads to misinterpretation of the measurement results. Moreover, the results of numerical simulation tests presented in this paper confirm the possibility of diagnosing the condition of rail joints by any vehicle passing over such a track equipped with a suitable system.

operational safety,numerical and experimental studies,rail vehicle dynamics,continuous welded rail track,operational safety

Many industrial rotating machines driven by asynchronous motors are often affected by detrimental torsional vibrations. In this paper a method of attenuation of torsional vibrations in such objects is proposed. Here, an asynchronous motor under a proper control can simultaneously operate as a source of drive and actuator. Namely, by means of the proper control of motor operation it is possible to suppress torsional vibrations in the object under study. Using this approach, transient and steady- state torsional vibrations of the rotating machine drive system can be effectively attenuated as well as its precise operational motions can be assured. The theoretical investigations are carried out by means of a structural mechanical model of the drive system and an advanced circuit model of the asynchronous motor controlled using two methods: the direct torque control – space vector modulation (DTC-SVM) and the rotational velocity controlled torque (RVCT) based on the momentary rotational velocity of the driven machine working tool. From the obtained results it follows that by means of the RVCT technique steady-state torsional vibrations induced harmonically and transient torsional vibrations excited by switching various types of control on and off can be suppressed as effectively as using the advanced vector method DTC-SVM.

rotating machine,drive system,control methods,asynchronous motor,torsional vibrations

The aim of the article is to develop a method for the analysis of tram dynamics related to safety during operation. To achieve this, a mathematical model of the vehicle represented by a multibody simulation MBS system is used. Models of tram with a classic and innovative drive, based on a system of independently rotating wheels on crank axles are analyzed. A new configuration of an innovative drive control of the considered vehicle with the use of braking of independent wheels is proposed. A new geometry of test track is presented. During numerical investigation the values of 'Y' leading forces of tram wheels with the considered innovative drive proved to be lower than in the corresponding vehicle with standard wheelsets. It has been demonstrated that the active control systems are of key importance and should be applied in such innovative tram drives.

maintenance of safety, reliability of trams, derailment of tramcar, numerical tests, drive with independently rotating wheel

The article presents an investigation of the stabilization of a cantilever pipe discharging fluid using electromagnetic actuators of the transformer type. With the flow velocity reaching a critical value, the straight equilibrium position of the pipe becomes unstable, and self-excited lateral vibrations arise. Supplying voltage to the actuators yields two opposite effects. First, each of the actuators attracts the pipe, thus introduces the effect of negative stiffness which destabilizes the middle equilibrium. Second, lateral vibrations change the gap in magnetic circuits of the actuators, which leads to oscillations of magnetic field in the cores and the electromagnetic phenomena of induction and hysteresis that impede the motion of the pipe. The combination of these two non-linear effects is ambiguous, so the problem is explored both theoretically and experimentally. First, a mathematical model of the system in form of a partial differential equation governing the dynamics of the pipe coupled with two ordinary differential equations of electro-magnetodynamics of the actuators is presented. Then, the equation of the pipe’s dynamics is discretized using the Galerkin procedure, and the resultant set of ordinary equations is solved numerically. It has been shown that the overall effect of actuators action is positive: the critical flow velocity has been increased and the amplitude of post-critical vibrations reduced. These results have been validated experimentally on a test stand.

fluid-structure interaction, pipe, flow, dynamic stability, electromagnetic actuator

The rotating machines with overhung rotors form a wide class of devices used in many types of industry. For this kind of rotor machines in the paper there is investigated an influence of dynamic and static unbalance of a?rotor, parallel and angular misalignments of shafts as well as inner anisotropy of rigid couplings on system dynamic responses. The considerations are performed by means of a hybrid structural model of the machine rotor-shaft system, which consists 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 a?sensitivity of the above-mentioned imperfections on excitation severity of rotor-shaft lateral vibrations and on motion stability of the machine in question.

overhung rotor-shaft, lateral vibrations, stability and sensitivity analysis, system imperfections

A scalable optimal control method for structural vibration mitigation is studied. The method relies on a structure's partitioning that leads to a set of dynamically interconnected subsystems. Each subsystem is operated with an individual subcontroller that collects the local state information and collaborates with the neighboring subcontrollers to estimate a short time prediction of the interconnecting forces defining the subsystem's boundary conditions. Using the extended model that represents the subsystem's dynamics together with the evolution of its boundary conditions, each subcontroller computes the control decision based on the solution to a finite‐time horizon optimal control problem. In order to cope with the changes in the boundary conditions, the optimal solution is computed repetitively according to the receding horizon scheme. The method is validated numerically for a cantilever structure equipped with actively controlled electromagnetic actuators and subjected to a variety of initial condition scenarios. The performance of the designed controller is tested by comparisons to the centralized and isolated decentralized controllers. The introduced system partitioning and distributed controller allow performing parallel computing which makes the method fully scalable and applicable to large‐scale structures. The computational complexity of the designed distributed control is studied for different settings in the modeling of the subsystem's boundary conditions.

active control, distributed control, modular structure, scalable optimization, stabilization

The problem of decentralized semi‐active stabilization of vibration of a beam structure is studied. The decentralized controller's architecture is attained by means of optimal system modelling. In this approach, based on a specially designed and optimized set of basis functions, the solution to the continuous Euler-Bernoulli beam equation is approximated by a discrete system, where the mass and stiffness matrices ensure that the assumed stabilizing control law can be operated by using solely the local state information. The performance of the method is examined through numerical experiments for a series of free‐vibration scenarios with comparison to competitive decentralized and centralized control strategies. The performance impact of the selection of the parameters of the optimal system model is also studied. The designed method allows practical modular arrangements of the control system and is applicable to large‐scale structures.

bilinear system, decentralized control, polynomial basis, semi-active control, stabilization

The article features the results of computer and experimental research on operational issues in the aspect of safety in relation to a freight wagon derailment on a railway track. It presents the knowledge regarding the methods of assessing the operational safety of rail vehicles on railroad tracks for the purpose of comparative analysis. The theoretical analyses were performed based on several methods that assess the safety of their derailments, qualifying for operational reliability, comparing them with the results obtained from experimental research. For the purpose of the research, a computer model of rail vehicle- railway track was created. It took into consideration dynamic parameters of elements used in the real track and rail vehicle. The results obtained from theoretical analyses were validated with experimental tests carried out on real objects (freight vehicle - test track, freight wagon - test rig). As part of the research, new test track geometry for testing rail vehicles was proposed. The results obtained in this way allowed estimating the conditions threatening the operation of a freight vehicle while running on the test rail infrastructure with different assessment criteria and to compare them.

operational safety, rail vehicle dynamics, derailment, experimental tests, numerical investigations

Torsional vibrations induced in drilling systems are detrimental to the condition of the machine and to the effectiveness of the engineering process. The cause of vibrations is a nonlinear and unknown friction between a drill string and the environment, containing jumps in its characteristics. Nonlinear behaviour of the friction coefficient results in self-excited vibration and causes undesirable stick-slip oscillations. The aim of this paper is to present a novel adaptive technique of controlling vibrating systems. The scheme is based on the linear quadratic regulator and uses direct measurements of the friction torque to synthesize its linear dynamic approximation. This approach allows generating a control law that takes into account the impact of the friction on the system dynamics and optimally steers the system to the desired trajectory. The controller's performance is examined via numerical simulations of the stabilization of the drilling system. The proposed solution outperforms the comparative LQG regulator in terms of the minimization of the assumed cost functional and the overall stability of the control system under the nonlinear disturbance.

vibration control, adaptive control, linear-quadratic-regulator, drilling control

An application of electromagnetic devices of the motional type (i.e. eddy-current dampers) to improve the dynamic stability of a cantilever pipe discharging fluid is proposed. When the flow velocity reaches a critical value, this system loses stability through the flutter. A contactless damping device is used. This actuator is made of a conducting plate attached to the pipe that moves together with it within the perpendicular magnetic field that is generated by the controlled electromagnets. During the motion the eddy currents in the plate and a resultant drag force of a viscous character are generated. First, an optimal control problem that aims to stabilise the system with the optimal rate of decrease of the system’s energy is posed and solved. Then a state-feedback parametrization of the obtained optimal control, which can be used in a closed-loop scheme is proposed. The effectiveness of the designed optimal controller is validated by making a comparison with the corresponding passive solutions on the specially designed and constructed experimental test stand of a pipe conveying air.

fluid–structure interaction, electromagnetic device, eddy-current damper, optimal control, stabilisation, smart structure

A method of vibration reduction based on activation of an MRE block that couples twin cantilever beams at their free ends is investigated. Four types of magnetorheological elastomers have been manufactured, and their rheological properties in a range of magnetic field intensities are established. Free vibrations of several double-beam structures with controllable damping members made of these MREs are investigated, and a method of semiactive control of such structures is proposed. The effects of compression of the elastomers and alignment of the magnets used to activate them are reported. The mathematical modeling of the system is verified experimentally.

This paper deals with the problem of applying electromagnetic devices of the motional type to improve the dynamic stability of a pipe conveying air. When the flow velocity reaches a critical value, the steady equilibrium position becomes unstable, and self-excited lateral vibrations arise. In contrast, electromagnetic devices of the transformer type have been demonstrated to be highly effective in the passive stabilization of such a system, as well as the active stabilization of similar non-conservative systems with a follower force. In the present paper, we apply a pair of motional devices made of a conducting plate which is attached to the pipe and moves together with it within the perpendicular magnetic field generated by the controlled electromagnets. This motion generates eddy currents in the plates and a drag force of a viscous character. In this setting, we first investigate the possibility of designing a stabilizing control within the region of the magnetic field where every passive solution results in an unstable or conservative state. For that purpose, we determine a practical condition justifying the existence of a stabilizing control for a given set of system parameters. Later we pose and solve an optimal control problem aiming at stabilizing the system with the optimal rate of decrease of the system's energy. The solution is examined by means of numerical simulations performed within the three regions of the flow velocity: low subcritical, where the Coriolis acceleration of the conveyed fluid generates the predominate damping force; high subcritical, where the inertia of the fluid begins to dominate the dynamics of the system; and low supercritical,where unstable flutter vibrations start to arise. The effectiveness of the designed optimal controller is validated by comparisons with the corresponding passive solutions.

fluid–structure interaction, electromagnetic device, optimal control, stabilization, smart structure

The aim of this paper is to demonstrate the possibilities of estimating the track condition using axle-boxes and car-bodies motions described by acceleration signals. In the paper, the results presented indicate the condition of tracks obtained from the preliminary investigation on the test track. Furthermore, the results from the supervised runs (on Polish Railway Lines) of electric multiple unit (EMU-ED74) with the prototype of track quality monitoring system installed on-board are described. As track quality indicator (TQI) algorithm, used in the mentioned prototype, a modified Karhunen–Loève transformation is used in preliminary preparing acceleration signals. The transformation is used to extract the principal dynamics from measurement data. Obtained results are compared to other methods of evaluating the geometrical track quality, namely methods which apply the Jsynth Synthetic Coefficient and Five Parameters of Defectiveness W5. The results from the investigation showed that track condition estimation is possible with acceptable accuracy for in-service use and for defining cost-effective maintenance strategies.

railway track monitoring, wheel–rail interaction, track quality indicator, acceleration signals, experimental investigation, track degradation.

The paper presents an analysis of a newly diagnosed cause of wheel thread wear in a freight wagon and also possible other causes of abnormal wear of wheels in freight wagon wheelsets are mentioned. Newly diagnosed cause for excessive wear of the railway wheel thread is an incorrect position of wheelsets in relation to the bogie frame. The paper presents results of measurements carried out on a real freight wagon to get identification of wheels’ wear and geometry of vehicle components. In order to analyze the influence of incorrectly positioned wheelset axles on the degree of wheel wear a numerical model of a freight wagon was developed. Numerical calculations at various speeds of wagon and several versions of wheelsets skew position were carried out. The results obtained from numerical tests i.e. a significant influence of non-parallel axles of wheelsets on abnormal wear of wheel threads are shown. Conclusions drawn from the computation results can be very useful at a running gear repairs as well as helpful in a regular maintenance process. It will also reduce the costs of repairs of wheelsets and extend their service life.

experimental and numerical tests, contact interaction, running gear, railway wheel thread wear

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.

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

The paper is devoted to the experimental and theoretical analysis of wheelset elastic properties on the railway vehicle-track interaction. Results of experimental measurements of stiffness components of wheelsets obtained by a new measurement method are shown. Some types of wheelsets are considered with different wheel-disk design. For the theoretical analysis of bending and torsional flexibility of the wheel and wheelset are used. To numerical modeling of the considered wheels and wheelsets models the Finite Element Method (FEM) are applied. Simulation of dynamic interaction between a railway bogie and a curved sector of track in the rigid multibody systems method (VI-Rail software) is modeled. Exemplary simulations results obtained from the bogie-track system model using flexible and rigid model of the wheel and wheelset are presented.

experimental tests, contact force, measurement, bending wheelset, torsional flexibility wheel

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.

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

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.

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

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.

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

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.

Optimal Control Theory, Periodical Vibrations, Vibration Reduction

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.

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

This paper presents the strategy of semi-active damping of vibrations of a beam span subjected to a moving load. Intermediate supports as controlled dampers significantly decrease transverse displacements in comparison with a system with permanently active dampers. The gain can reach 40% in the case of high speed loads. In a real structure with a load moving at 3 m/s, considered in this paper, the improvement is about 10%. The control is determined by a minimization procedure. Numerical simulations are confirmed experimentally on a stand with a length of 4 m. Controlled dampers can be replaced with an intelligent material. The potential applications are in transport or robotics.

Moving inertial load, Intelligent adaptive control, Semi-active damping, Beam vibration

The paper deals with the investigation of some phenomena which are essential for dynamic interaction of a wheelset or bogie with the railways track. The track is modeled as discrete–continuous system composed of rails, fastening systems and sleepers interacting with ballast by means of viscous–elastic elements. Transient and stationary problems are investigated. The stationary periodic problems are connected with wave propagation in stopping bound, passing bound and mistuning. In this paper, a review of selected problems and exemplary results of simulation and experimental investigations is given supplemented by a few results of analysis and simulation.

Moving load, Resonance, Periodicity, Passing band, Mistuning

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.

Machine drive system, Asynchronous motor, Electromechanical coupling

The paper is devoted to the study of dynamical behaviour of railway tracks as continuous systems (rails) supported by periodically spaced sleepers and subjected to moving concentrated loads. Several cases of dynamical problems, where elastically supported beams are excited by a moving concentrated force, are considered. In particular, the study is focused on interactions with structure periodic in the space. Results on one-dimensional structures are extended to the case of a two-dimensional system. The problems of stopping bands, passing bands, and mistuning are also mentioned.

railway track, moving load, dubble sleepers, vibration

Artykuł poświęcony jest badaniom rozkładu ciepła wywołanego tarciem w ukła-dach hamulcowych stosowanego w pojazdach szynowych dużej prędkości. W pracy zapre-zentowano wyniki eksperymentalnych badań przeprowadzone na rzeczywistym obiekcie w skali 1:1. Nowością w pracy jest fakt analizy układu hamulcowego, w którym para cierna charakteryzowała się segmentacją powierzchni ciernej okładziny o dwóch materiałach ciernych. Materiałami tymi był kompozyt i spiek. W pracy przedstawiono także teoretyczną analizę i wyniki numeryczne ilustrujące dystrybucję ciepła w elementach modelu tarczy hamulcowej. Wykorzystano w tym celu na metodę elementów skończonych.

systemy hamulcowe dużych prędkości, ciepło tarcia, okładzina hamulcowa spiekana-kompozytowa

Artykuł dotyczy zagadnień monitorowania oddziaływań układu pojazd-tor w czasie eksploatacji. Oddziaływania te pochodzą od dynamiki pojazdu jak również od kinematycznych wymuszeń stanowiących efekt niedoskonałości toru. Praca zawiera opis badań eksperymentalnych na rzeczywistym obiekcie kolejowych, na podstawie których rozpatrywany jest wskaźnik określający jakość toru. W artykule przybliżono także monitorowanie z funkcją diagnozowania układu pojazd szynowy – tor. Zaprezentowano prototyp systemu monitorowania układu pojazd szynowy – tor. Zagadnienia rozpatrywane w artykule mają na celu rozpoznanie miejsc występowania zaburzeń na szlaku kolejowym oraz wskazania rodzaju tejże niedoskonałości infrastruktury. Wykorzystanie wskaźnika jakości toru po-winno prowadzić do określenia stanu toru, tj. globalnej oceny toru oraz wybranych jego parametrów. W artykule ograniczono się do omówienia wyników badań na doświadczalnym torze badawczym. W treści artykułu podano wstępne propozycje klasyfikacji stanu toru oparte na jakości oddziaływania pojazdu szynowego z torem oraz zaproponowano dalsze kierunki badań dotyczących tego zagadnienia.

oddziaływanie dynamiczne pojazd-tor, wskaźnik jakości toru, stan toru

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.

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

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

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

The paper is devoted to the evaluation of wheel-rail interaction quality and possibility of utilize of acceleration measurement for the determination of quality of tracks. After review of methods used for this purpose in Germany, Austria and other countries, the proposal used for experimental investigation by PESA S.A. will be reported and some theoretical analysis for the track quality evaluation will be given.

railway wheel, railway track, monitoring, wheel-rail dynamics

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.

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

The paper is devoted to the experimental, theoretical analysis and computer simulation of influence of elastic properties of contact stiffness and wheel-plate stiffness on the forces of vehicle-track interaction. Three types of wheels are considered with different contact stiffness and wheel-plate design. Exemplary simulation of freight car interaction with track which posses one corrugated rail for each type of wheel is presented.

Contact stiffness, Rail corrugation, Elastic wheel, Wheel-rail interaction, Simulation

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.

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

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.

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

The paper is devoted to a computer simulation of brake pad/brake disc dynamic interaction. The main purpose of the studies is a numerical analysis of friction pair dynamics, aiming at describe generation of vibration related to the process of transition phenomena associated with braking. To investigation will be used environment of Automatic Dynamic Analysis of Mechanical Systems. In the analysis is used two-dimensional friction model. The results show the slip-stick and creep phenomenon

vibrations excited by friction, self-excited of vibrations, slip-stick, creepage

The paper deals with the problem of stabilization of vibrations of the load carrying structure via adaptive damping performed with a smart material. The properties of such a material must ensure reduction of vibrations, especially accelerations and displacements of selected stationary or follower points in a higher range than in the case of the material with homogeneous bilateral characteristics. Analytical calculations and numerical simulations proved the efficiency of the approach. Results obtained with the testing system equipped with magnetorheological controlled dampers will allow us to prove experimentally assumed control strategies and rheological properties of the filling material.

control, moving inertial load, vibrations, smart materials

In the paper we present results of vibration measurements in the train and on the base of the railroad in tunnels of Warsaw Underground. Measurements were performed at straight and curved sections of the track. The paper is focused on the influence of the lateral slip in rail/wheel contact zone on the generation of vibrations and a noise. Vibrations were analyzed in terms of accelerations, velocities or displacements as a function of time and frequency. Results ware compared with the experiment of rolling of the wheel with lateral sleep. In both cases we observed double periodic oscillations.

dynamic train-track interaction, ground borne vibrations, curved and straight track, rolling

The paper deals with the dynamic phenomena accompanying the wheel rolling over a road (rail, track), with lateral slip effects. They occur in rol-ling of a wheel and wheelset on a straight track in the case of lateral load and especially on curves. Different curvature radii and rotary oscillations of wheelsets result in skew rolling and, in turn, in lateral slip oscillation in the contact zone between the wheel and rail. It significantly increases noise and wear in real structures. Double periodicity of motion was de-tected in an underground train. Hitherto, this phenomenon has not been reported in the literature. Experimental investigation was performed on a test stand for various parameters: the angle of skew rolling, velocity and contact pressure. Results were related to a two degree-of-freedom the-oretical system. In the case of steel/polyester and polyamide/polyester friction pair, qualitatively similar results were obtained.

rolling, friction, lateral slip, wheel-rail interaction

W pracy zaprezentowano wstępną ocenę nowej metodologii stosowanej do identyfikacji obciążeń wywieranych przez przejeżdżające pojazdy na nawierzchnię drogi. Proponowane rozwiązanie opiera się na pomiarze lokalnych odkształceń powstałych na powierzchni detektora nacisku. Celem jest rozwój koncepcji oraz sprawdzenie nowego typu dynamicznej wagi drogowej oraz algorytmu rozwiązania zagadnienia odwrotnego. Przyjętą koncepcję wstępnie sprawdzono wykorzystując metodę elementów skończonych. Przeprowadzono też testy laboratoryjne proponowanego urządzenia. Uzyskano dzięki temu wstępne dane do kalibracji urządzenia. Ważnym zagadnieniem było sprawdzenie czynników wpływających na identyfikację obciążeń. Skuteczność rozwiązania sprawdzono w badaniach doświadczalnych wstępnej wersji urządzenia w warunkach drogowych.

ważenie pojazdów w ruchu, identyfikacja obciążeń, czujniki piezoelektryczne, badania eksperymentalne

W pracy podjęto tematykę dynamicznego oddziaływania pojazdów szynowych na tor, z uwzględnieniem zagadnienia drgań bocznych infrastruktury kolejowej wywoływanej przejazdem pojazdu szynowego. Na podstawie pomiarów zarejestrowanych w rzeczywistych obiektach kolejowych oraz na eksperymentalnym stanowisku laboratoryjnym wykazano istnienie drgań dwuokresowych w kierunku prostopadłym do płaszczyzny toczącego się koła. Zjawisko to nie było dotąd badane i przedstawiane w literaturze przez innych badaczy. Pojawia się ono m.in. przy obciążeniu bocznym pociągu oraz na łukach toru. Używając model numeryczny pojazdu szynowego, stworzony w programie Vi-Rail, wykorzystujący elementy wieloczłonowe (multibody system), uzyskano odpowiedź dynamiczną o charakterze zbliżonym jakościowo do zarejestrowanych w obiektach rzeczywistych i w laboratorium. Zaprezentowane w pracy wyniki oraz ich analiza mogą zainteresować badaczy zajmujących się transportem szynowym, kontaktem tocznym i zużyciem kół i szyn kolejowych.

oddziaływanie pojazdu z torem, drgania torowiska, toczenie z poślizgiem bocznym, kontakt toczny

The paper presents the results of vibration measurements on line of railway during passages of a train at a constant speed. The measurements have been performed on a railway track at straight and curve sections as well as and inside the train on the floor. The experimental results exhibited higher amplitudes of vibrations on the curve of the track than on its straight segments. The lateral slip in rail/wheel contact zone is considered as a possible reason of such a phenomenon.

railway vibrations, dynamic train-track interaction, ground borne vibrations, moving load

Praca dotyczy analizy dynamicznych zjawisk towarzyszących toczeniu koła po drodze (torze), przy jednoczesnym oddziaływaniu czynników wywołujących poślizg w kierunku prostopadłym do kierunku toczenia. Przypadki takie występują przy toczeniu się koła kolejowego po szynie na odcinkach prostych w przypadku oddziaływania wiatru oraz na łukach. Występowanie poślizgów bocznych przy jeździe na łukach spowodowane jest różnicą promieni krzywizny obu szyn i oscylacjami obrotowymi zestawu kołowego w płaszczyźnie toru. Na skutek ukośnego ustawienia płaszczyzn kół względem chwilowego kierunku toczenia dochodzi do bocznych poślizgów w strefie kontaktu koła z szyną. Oscylacje te mają niekorzystny wpływ zarówno na zużycie kół i szyn, jak i na otoczenie, ze względu na emisję hałasu. Otrzymane wyniki eksperymentalne pozwoliły na opracowanie modelu matematycznego zjawiska. Zaobserwowano dwuokresowy charakter drgań wywołany siłą boczną. Zbadano wpływ prędkości toczenia, siły nacisku oraz kąta między płaszczyzną toczącego koła a drogą na dwuokresowe drgania w kierunku osiowym koła.

nawierzchnia, transport szynowy, poślizg boczny, kontakt koło-szyna

Ogumienie pojazdu samochodowego jest elementem, który znajduje się w bezpośrednim kontakcie z nawierzchnią drogi i przenosi obciążenie wynikające z wymuszenia kinematycznego pojazdu. Właściwości opony pojazdu samochodowego wpływają bezpośrednio na bezpieczeństwo czynne kierowcy oraz pasażerów. Stąd ogumienie ciągle stanowi przedmiot badań i prac rozwojowych. Skutkiem tych prac jest wprowadzanie nowych materiałów i technologii wytwarzania, które prowadzą do poprawienia właściwości jezdnych i eksploatacyjnych (zmniejszenia masy opony, zużycia i odkształceń). Ruch toczny koła wywołuje dyssypację energii związaną z tarciem poślizgowym w łożyskach, tłumienie postaciowe związane z uginaniem się opony oraz straty wentylacyjne.

koło ogumione, poślizg, kontakt toczny, równie falowe

Rolling contact has been investigated intensively during last decade [1, 2]. However, generation of corrugations, the fundamental problem of rolling in railway transportation, is still not completely explained. In the paper we consider dynamic phenomenon, which occur in rolling of the wheel over the rail, with lateral slip. Such cases are involved by wind blows (both on curved and straight tracks), deformation of wheels, wheelsets and rails, different linear velocity of wheels on curves and rotatory oscillations of wheelsets.
Skew wheel plane related to the direction of rolling results in lateral slip in rail/wheel contact zone. The rail/wheel system oscillates and generates noise. In the same time the wear increases considerable and negatively influences the safety of transportation. Corrugations are visible results of this oscillatory wear (Fig. 1). However, the phenomenon can be observed also in rolling of a tire over the road and the contact of rolls with guide. In all cases friction is the main reason of the described phenomenon. The friction law influences it qualitatively and qualitatively.

Experimental investigations

When freight rolling stock operators optimize their own costs and profits, one of many steps is to increase the number of wagons. As the freight trains become longer, the dynamics of individual freight wagons in the longitudinal direction becomes important in terms of safety. In this case, the forces involved between the wagons have a key influence on safety against derailment. The derailments of wagons of long freight trains frequently occurred around the world, which caused tremendous losses. The presented in the paper approach to the results obtain from experimental tests carried out on real objects (freight train - test track) to validate a theoretical model are used. Thus, as a result of these numerical investigations by use of the theoretical model, a tool based on multi-body simulations has been developed to provide longitudinal behaviour of freight wagon passing through S-curves of varying curvatures.

longitudinal dynamics, experimental investigations, theoretical investigations, freight trains, railway dynamic

The rotating machines with overhung rotors form a wide class of devices used in many types of industry. For this kind of rotor machines in the paper there is investigated an influence of dynamic and static unbalance of a rotor, parallel and angular misalignments of shafts as well as inner anisotropy of rigid couplings on system dynamic responses. The considerations are performed by means of a hybrid structural model of the machine rotor-shaft system, which consists 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 a sensitivity of the above-mentioned imperfections on excitation severity of rotor-shaft lateral vibrations and on motion stability of the machine in question.

motion stability, rotating machines, overhung rotors, industrial fan, numerical calculations, experimental test

In the paper dynamic electromechanical interactions between the rail-way drive systems and their driving electric motors are investigated. These are drive systems of high-speed trains (HST) and locomotives driven by AC motors. In particular, there is considered an influence of negative electromagnetic damp-ing generated by the asynchronous motor on a possibility of excitation of reso-nant torsional vibrations. The theoretical calculations have been performed by means of the advanced structural mechanical models. Conclusions drawn from the computational results can be very useful during a design phase of these ob-jects as well as helpful for their users during a regular maintenance.

railway drive, electromechanical interactions, AC Motors, railway dynamic, numerical investigation

The existing European standard EN 14363 covers all necessary tests for different railway vehicles, but it is inadequate for tram vehicles, especially in safety against a derailment examination. Its operational conditions are much different. Trams overcome horizontal curves with much smaller radii than railway vehicles. There is a large diversity in wheel-rail pairing, i.e. almost every public transport operator uses a different wheel profile. In the running gear design much more rubber-metal elements are used in order to ensure a low-floor interior and to keep the kinematic envelope. Apart from standard vehicle configuration, i.e., a carbody on two bogies, in modern tram designs numerous arrangements are applied: wagons with one outer bogie, wagons with one centered bogie, wagons without bogies (sedan) etc., where twisting shims cannot be used to achieve the required twist. The described issues imply that the methodology of safety against derailment described in EN 14363 standard cannot be applied without any modifications. This paper presents a new proposal for a simulation safety against derailment for a vehicle with an arbitrary configuration of wagons and running gears. The numerical analyses have been performed by means of the Simpack Rail software

Safety against derailment, Tram vehicle Numerical, simulation Running dynamics, Simpack rail software

Torsional vibrations of steam turbo-generator rotor-shaft-lines coupled with bending vibrations of exhaust blades still constitute an important operational problem for this type of rotor-machines. Therefore, this work proposes a relatively simple approach for efficient suppression and control of transient and steady-state turbo-generator shaft torsional vibrations excited by short circuits in a generator or power-lines, faulty synchronization, negative sequence currents and by sub-synchronous resonances in the turbo-generator-electric network system. This target has been achieved by means of semi-actively controlled rotary dampers with the magneto-rheological fluid. Regular operation of such devices installed in a given turbo-generator rotor-shaft line enables suppression of dangerous torsional oscillations.

control of torsional vibrations, the turbo-generator, rotary magneto-rheological dampers, Bi-directional active torsional vibration damper

In the paper, simulation results of safety against derailment for a tramway vehicles with an arbitrary configuration of wagons and bogies is presented. The existing European standard EN 14363 covers all necessary tests for different railway vehicles, but it is inadequate for tramway vehicles, especially in safety against a derailment examination. Its operational conditions are much different. The described observations suggest that the methodology of safety against derailment testing described in the EN 14363 standard cannot be used without any modifications in the case of testing of tramway vehicles. On the basis of the computational results, a significant influence of different configurations of urban tramway vehicles on the wheel-rail contact forces was discussed, in particular on the Y/Q derailment factor.

tramway dynamics, safety against derailment, simpack, numerical study

In this paper, the influence of electromechanical interaction in an electric motor on the railway vehicle driving system dynamics was investigated. This is the train driven by DC. In particular, there is considered influence of electromagnetic field between a rotor and stator on excitation of resonant torsional vibrations of the drive system. Conclusions drawn from the computational results can be very useful during the design phase of these devices as well as helpful for their users during regular maintenance.

railway drive system, electromechanical coupling, numerical analysis, electric motor, torsion vibration, railway vehicle operation

In the paper there is presented a reliable structural model of the rotating mechanical systems as well as mathematical models of the stepping, synchronous and asynchronous motors, by means of which electromechanical coupling effects can be thoroughly investigated. An importance and severity of these phenomena, not sufficiently explored till present, have been demonstrated by results obtained for transient and steady-state operational conditions in the computational examples concerning torsional vibrations of drive trains with various electric motors.

structural model, electric motors, mechanical systems, electromechanical coupling

In the paper, a dynamic electromechanical interaction between the selected kind of rotating machines and their driving electric motors is investigated. These are the high-speed beater mills and crushers as well as blowers, pumps and compressors, all driven by the asynchronous motors through elastic couplings with linear and non-linear characteristics. In particular, there is considered an influence of negative electromagnetic damping generated by the motor on a possibility of excitation of resonant torsional vibrations. Moreover, for the asynchronous motor in transient and steady-state operating conditions, there are tested several control strategies which are based on the closed-loop vector and scalar principles. The theoretical calculations have been performed by means of the advanced structural mechanical models. Conclusions drawn from the computational results can be very useful during a design phase of these devices as well as helpful for their users during a regular maintenance.

Rotor-machine, Asynchronous motor, Electromechanical interaction, Torsional vibrations, Control strategies

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.

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

The paper contain description of certain dynamical problems connected with the kinematic excitation of railway track. Some phenomena are given which may create high loads, track degradation and fatigue of wheelset axles. An alternative approach to measurement rail vehicle overload are given. Some examples of experimental investigations are given which pointed out that the dynamical load acting on the track can be a few times higher as the static load. In the paper the results obtained from the electromechanical drive model describing the torsion vibration of wheelset caused by passing through gaps in a single rail of track are presented.

wheel-rail dynamics, vehicle-track interaction, track and vehicle degradation

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.

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

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.

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

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.

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

The paper deals with the problem of stabilization of vibrations of the load carrying structure via adaptive damping performed with a smart material. The properties of such a material must ensure reduction of vibrations, especially accelerations and displacements of selected stationary or follower points in a higher range than in the case of the material with homogeneous bilateral characteristics. Analytical calculations and numerical simulations proved the efficiency of the approach. Results obtained with the testing system equipped with magnetorheological controlled dampers will allow us to prove experimentally assumed control strategies and rheological properties of the filling material.

control, moving inertial load, vibrations, smart materials

Praca opisuje zagadnienia dynamicznego oddziaływania podziemnego pojazdu szynowego na tor. Oddziaływanie to wywołuje drgania, które za pośrednictwem konstrukcji toru, tunelu oraz gruntu propagowane są na pobliskie konstrukcję i budynki. Ze względu na zagęszczenie ruchu ulicznego podziemna komunikacja jest obecnie jedyną alternatywą płynnego przemieszczania się osób w wielkich aglomeracjach miejskich. Sprzyja to rozwojowi i modernizacji podziemnej kolei miejskiej, w której jako jednym z celów stawianych projektantom jest minimalizacja powstania drgań propagujących się na otaczające środowisko W nauce również można zaobserwować wzrost zainteresowania zjawiskami powstawania i propagacji drgań w gruncie, wywołanych przejazdem pojazdów kolei podziemnej. Głównym pytaniem nurtującym badaczy jest kwestia kontroli układu pojazd/tor i zmniejszenie powstających szkodliwych wibracji i hałasu. Ze względu na wielorakie rozwiązana konstrukcyjne pojazdów i torowisk kolei podziemnej trudno jest zaproponować jednoznaczne rozwiązanie.

metro, oddziaływania podziemnego pojazdu szynowego, wibroizolacja, grunt

Zagadnienia dynamicznego oddziaływania pojazdu metra na tor są analizowane w pracy. Oddziaływanie to wywołuje drgania, które za pośrednictwem konstrukcji toru, tunelu oraz gruntu propagowane są na pobliskie konstrukcję i budynki. Ze względu na zagęszczenie ruchu ulicznego podziemna komunikacja jest obecnie jedyną alternatywą płynnego przemieszczania się osób w wielkich aglomeracjach miejskich. Sprzyja to rozwojowi i modernizacji podziemnej kolei miejskiej, w której jako jednym z celów stawianych projektantom jest minimalizacja powstania drgań propagujących się na otaczające środowisko W nauce również można zaobserwować wzrost zainteresowania zjawiskami powstawania i propagacji drgań w gruncie, wywołanych przejazdem pojazdów kolei podziemnej. Ze względu na wielorakie rozwiązana konstrukcyjne pojazdów i torowisk kolei podziemnej trudno jest zaproponować jednoznaczne rozwiązanie. Głównym pytaniem nurtującym badaczy jest kwestia kontroli układu pojazd/tor i zmniejszenie powstających szkodliwych wibracji i hałasu.

Metro Warszawskie, tunel metra, kolej podziemna, badania eksperymentalne

Analizy dynamicznych zjawisk towarzyszących toczeniu koła po drodze (torze), przy jednoczesnym oddziaływaniu czynników wywołujących poślizg w kierunku prostopadłym do kierunku toczenia są analizowane w artykule. Przypadki takie występują przy toczeniu się koła kolejowego po szynie na odcinkach prostych w przypadku oddziaływania wiatru oraz na łukach. Występowanie poślizgów bocznych przy jeździe na łukach spowodowane jest różnicą promieni krzywizny obu szyn i oscylacjami obrotowymi zestawu kołowego w płaszczyźnie toru. Na skutek ukośnego ustawienia płaszczyzn kół względem chwilowego kierunku toczenia dochodzi do bocznych poślizgów w strefie kontaktu koła z szyną. Oscylacje te mają niekorzystny wpływ zarówno na zużycie kół i szyn, jak i na otoczenie, ze względu na emisję hałasu. Otrzymane wyniki eksperymentalne pozwoliły na opracowanie modelu matematycznego zjawiska. Zaobserwowano dwuokresowy charakter drgań wywołany siłą boczną.

dwuokresowy charakter drgań, kontakt koło-szyna,numeryczne badania

Pojazdy tramwajowe charakteryzują się dużą różnorodnością w zakresie konfiguracji struktur nadwozi oraz układów biegowych. Ma to związek z ich eksploatacją w wysoko zurbanizowanych obszarach miejskich i koniecznością przystosowania do masowej obsługi podróżnych o różnych potrzebach przewozowych
(osoby o ograniczonej możliwości ruchowej, osoby na wózkach inwalidzkich, osoby z wózkami dziecięcymi). Nie bez znaczenia jest również istniejąca infrastruktura (minimalne wartości promieni łuków poziomych i pionowych, wysokości krawędzi przystankowej względem poziomu główki szyn). W stosunku do pojazdów kolejowych nie istnieją międzynarodowe regulacje dotyczące badań ruchowych, w tym w szczególności dla warunków bezpieczeństwa przed wykolejeniem. W związku z tym opracowano nową, uniwersalną metodykę badań symulacyjnych kryteriów bezpieczeństwa przed wykolejeniem pojazdów tramwajowych, bez względu na konfgurację nadwozi danego tramwaju, typu wózka czy szerokość toru. Zaprezentowano założenia nowej metodyki oraz przeprowadzono symulacje dla kilku popularnych na rynku konfguracji tramwajów. Porównano wyniki, otrzymane dla pojazdów z klasycznymi zestawami kołowymi oraz dla pojazdów wyposażonych w zestawy kołowe z niezależnie obracającymi się kołami.

Pojazdy tramwajowe, układy biegowe, symulacje, zestawy kołowe z niezależnie obracającymi się kołami

The paper presents a simple and fast method for predicting the vibrations of a vehicle moving on a track with a given technical condition. In the proposed approach, transfer function matrix models describing the dynamics of train components caused by the interaction of the rail vehicle-track system were used to analyze. The propagation of vibrations generated from the interaction of the wheel set with the track to selected elements of the rail vehicle is approximated by frequency-dependent homogeneous relations. The developed numerical vehicle-track model was generated on the basis of recorded accelerations at selected measurement points of a real rail vehicle and from track geometric data collected by a measuring trolley at given speeds of the entire system. The developed method is based on a model of the rail vehicle system.

A composite additively manufactured material for controlled sound absorption is proposed. The operation of the material is based on its changeable microgeometry with steel balls that modify propagation of acoustic waves when subject to an external magnetic field. Both numerical predictions and experimental verification is provided.

Majority of industrial machinery and several mechanisms are driven by asynchronous motors. Such electro-mechanical systems are often affected by detrimental torsional vibrations, suppression of which is commonly performed by more or less effective passive, semi active and active dampers. In this paper there is proposed an alternative method of attenuation of torsional vibrations in such objects. Here, an asynchronous motor under the proper vector control can simultaneously operate as a source of drive and actuator. Using this approach, transient and steady-state torsional vibrations of the driven mechanical system can be effectively suppressed as well as its precise operational motion can be assured. The theoretical investigations are carried out by means of an advanced structural mechanical model of the drive system and circuit model of the asynchronous motor controlled using two methods: the direct torque control (DTC-SVM) and the rotational velocity controlled torque method (RVCT) originally developed in this paper. In the computational examples performed for three representative drive systems torsional vibration control ability is analyzed for various dynamic properties of the mechanical part and several parameters of the asynchronous motor control. From the obtained results it follows that for majority of tested parameters, transient torsional vibrations excited by step-wisely disturbed loadings of the driven object are successfully attenuated using both abovementioned vector control strategies. However, a suppression effectiveness of resonant steady-state torsional vibrations by means of these methods depends on the specific case of an asynchronous motor with a given electromagnetic stiffness in the stable operational range of its static characteristics.

active control, torsional vibrations, asynchronous motor, rotating systems, driving asynchronous motor, driving motor

Safe operation and efficient of trains require assessment of its running behaviour. When freight rolling stock operators optimize their own costs and profits, one of many steps is to increase the number of wagons. As the freight trains become longer, the dynamics of individual freight wagons in the longitudinal direction becomes important in terms of in-service behaviour. In this case, the forces involved between the wagons have a key influence on safety against derailment. Safety against derailment is one of primary criteria for assessing the reliability of rail vehicle operation. The derailments of wagons of long freight trains frequently occurred around the world, which caused tremendous losses. Statistics from Australia, Canada, China revealed that the freight trains account for the vast majority of mainline derailments.

longitudinal dynamics, freight trains, experimental and theoretical investigations, trains dynamics, wheel-rail interaction

Trams with independently rotating wheels (IRW) enable to increase a comfort of traveling by lowering the floor level along the entire length of the vehicle, in particular above the bogies. In these trams such solution imposes a different design of motor bogies. In this construction of the bogies, four independent motors mounted on the bogie frame are connected each by a gear-stage with a single running-wheel. By means of the appropriate control algorithm guiding driving torques in curved sections of the railway track can be generated. Trams must ensure a high level of safety of passengers, and one of its aspect is safety against derailment. This article presents an original simulation method to investigate a level of safety against derailment for such vehicles. Principles of this method are independent of the tram car configuration. Using this approach, structural analysis of trams was carried out, which tested drive control in the boogie equipped with independently rotating wheels. Here, numerous simulations of motion on curved tracks were performed by means of various wheel drive control algorithms.

research safety, safety against derailment, derailment of trams, trams with independently rotating wheels, independently rotating wheels

In the present paper, the authors try to find distinguishable characteristics based on acceleration data obtained from a railway car body. Those quantities allow constructing diagnostic maps, which in turn can be used to classify vehicles clearly as damaged or undamaged. In this approach, the assessment is based on measurements taken from both an undamaged and damaged rail vehicle. The data are compared by methods of artificial intelligence. The aim of this paper is to study aspects of a pure signal-based approach to the end of a quick recognition of damage by assessment of selected parameters of sensor data in real time.

analysis of measured signals, experimental investigations, artificial intelligence, railway wagon, quick recognition of damage, damage diagnostic, neural networks

Torsional vibrations of steam turbo-generator rotor-shaft-lines coupled with bending vibrations of exhaust blades still constitute an important operational problem for this type of rotor-machines. Therefore, this work proposes a relatively simple approach for efficient suppression and control of transient and steady-state turbo-generator-shaft torsional vibrations excited by short circuits in a generator or power-lines, faulty synchronization, negative sequence currents and by sub-synchronous resonances in the turbo-generator-electric network system. This target has been achieved by means of semi-actively controlled rotary dampers with the magneto-rheological fluid. Regular operation of such devices installed in a given turbo-generator rotor-shaft-line enables suppression of dangerous torsional oscillations.

control of torsional vibrations, turbo-generator, shaft-lines vibrations, rotary magneto-rheological dampers, new rotary dampers

The aim of investigation is developed a reliable structural model of the traction vehicle with AC motors which drive it. Changes of parameters resulting from the movement of the vehicle in relation to the conditions of the wheel-rail co-operation might be the reason for system instability. For a reliability and security of drive system of railway vehicles driven by electric motors, the electromagnetic output traction force and torques should drive stably. Otherwise, the train drive-shaft vibrations caused by motor torque ripple will affect fatigue life of the responsible drive system components and an operation security of the driven railway vehicles. The methods developed by the authors and presented in this paper could be applied for creating some basis of vehicle drive system designs with more efficient movement-traction parameters and for increasing an efficiency of the traction vehicles characterized by high levels of power and travelling speeds.

railway drive system, electromechanical coupling, AC motor, full sprung wheelset drive

In In the paper, a new proposal of simulations safety against derailment for a tramway vehicles with an arbitrary configuration of wagons and running gears is presented. The existing European standard EN 14363 [1] covers all necessary tests for different railway vehicles, but it is inadequate for tramway vehicles, especially in safety against a derailment examination. Its operational conditions are much different. Tramways overcome horizontal curves with much smaller radii than railway vehicles. There is a large diversity in wheel-rail pairing, i.e. almost every public transport operator uses a different wheel profile. Apart from standard vehicle configuration, i.e., a carbody on two bogies, in modern tram designs varoius arrangements are applied. The described problems suggest that the methodology of safety testing before derailment described in the EN 14363 standard cannot be used without any modifications in the case of testing tramway vehicles.
Based on the obtained computational results, an essential influence of various municipal tramway vehicle designs and configurations on wheel-rail contact forces, in particular, on the derailment factor Y/Q, is discussed. The simulation results confirm the assumption that the track conditions for safety against derailment described in standard [1] addressed to the railway vehicles are not suitable for investigations of the light municipal trams. Moreover, one can remark that relatively low travelling speeds of trams do not guarantee a sufficient safety against derailment with specific vehicle configuration and extreme track geometry (small arc radius and zero cant). Such observations cause the need for further analysis of the discussed topic.

tramway dynamics, safety against derailment, Simpack Rail, MBS

The knowledge about torsional vibrations of drive transmission systems of railway vehicles is of a great importance in the dynamics of such mechanical systems. To ensure a reliability and unconditional security of high speed electric multiple unit (HSEMU) drive by AC motors, the electromagnetic output traction force and torques should drive stably. Otherwise, the shaft train vibration caused by motor torque ripple will affect a fatigue life of this device and the operation on the driven object. In the paper, a dynamic interaction between the torsionally vibrating HST drive sys-tem and the driving asynchronous motor was investigated. The results of wheelset torsional vibration analysis have shown that the first mode with torsional eigenfre-quency of the considered wheelset with electric motor is equal to109 Hz and the sec-ond torsional eigenfrequency is equal to 680 Hz. The basic torsional eigenvibration property is that the first wheel vibration direction is opposite to that of second wheel. The second torsional eigenvibration property is that the vibration directions of two wheels are coincident and the direction of electric motor connection elements is op-posite to the wheels. In the paper there was shown that static torque characteristics of the AC motor are correlated with its electromagnetic negative damping zones. This negative damping can be responsible for instability of the entire drive train. Concern-ing the transient and steady-state dynamic responses determined for the considered HST drive system, one can state that the studied phenomenon of electromechanical interactions should become an object of further investigations.

Railway drive system,The direct-drive, Electromechanical coupling, AC motors

Pipe Conveying Fluid, Electromagnetic Actuator, Stability, Flutter Experiment

Existing European standard EN 14363 covers all necessary tests for different railway vehicles, but it is inadequate for tram vehicles, especially in safety against a derailment examination. Its operational conditions are much different. Trams overcome horizontal curves with much smaller radii than railway vehicles. There is a large diversity in wheel-rail pairing, i.e. almost every public transport opera-tor uses a different wheel profile. In the running gear design much more rubber-metal elements are used in order to ensure a low-floor interior and to keep the kinematic envelope. Apart from standard vehicle configuration, i.e., a carbody on two bogies, in modern tram designs numerous arrangements are applied: wagons with one outer bogie, wagons with one centered bogie, wagons without bogies (sedan) etc., where twisting shims cannot be used to achieve the required twist. It should be also mentioned that in the low-floor trams there are frequently applied independently rotating wheels (IRW) which are individually driven. The dynamic behaviour of the trams equipped with the IRW wheelsets is significantly different from that of the vehicles with the classical wheelsets. The described issues imply that the methodology of safety against derailment described in EN 14363 stand-ard cannot be applied without any modifications. This paper presents a new pro-posal for a simulation safety against derailment for a vehicle with an arbitrary configuration of wagons and running gears. The numerical analyzes have been performed be means of the SIMPACK software.

safety against derailment, tram vehicle, numerical simulation, run-ning dynamics, SIMPACK software

Drive systems are one of the key components in railway vehicles. The need of an easy and effective monitoring and diagnosis technique has led to the increasing use of motor current signature analysis. Wheelsets, bearing and toothed gear faults in the railway drive system run by an induction motor causes change in its stator current spectrum. The above-mentioned defects in the electric drives cause variations of load irregularities in the magnetic field which in turn change the mutual and self-inductance causing side bands across the line frequency. Results of this analysis presented in the paper 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. The main objective of this paper is shown influence such faults in the railway drive system on motor current signature. Fast Fourier Transform (FFT) is initially employed for a first comparison between a healthy and a defective system. In the next step, wavelet analysis is used. Base wavelet has been selected on the basis of wavelet selection criteria - Maximum Relative wavelet energy. Additional this investigation has proved that the torsional stiffness and damping of drivetrain system strongly affect amplitudes of the self-excited vibrations which effects on motor current signatures of induction motor. Conclusions drawn from the computational results can be very useful during a design phase of diagnostic and monitoring devices as well as helpful for their users during a regular operation and maintenance

drive system, condition monitoring, self-excited vibrations, railway vehicles, electromechanical interaction

W artykule przedstawiono wyniki badań eksperymentalnych i numerycznych dotyczących zagadnień wykolejenia wagonu towarowego. Przybliżono charakteryzację stanu wiedzy dotyczącej metod oceny bezpieczeństwa pojazdów szynowych przed wykolejeniem, w celu ich porównania. W pracy przeprowadzono teoretyczne analizy porównawcze według kilku metod, które ocenią bezpieczeństwo przed wykolejeniem porównane z badaniami eksperymentalnymi. Na potrzeby analiz teoretycznych powstał numeryczny model układu pojazd szynowy-tor. Model ten uwzględniał parametry dynamiczne elementów zastosowanych w rzeczywistym pojeździe. Wyniki analizy teoretycznej poparto badaniami eksperymentalnymi przeprowadzonymi na rzeczywistym obiekcie (wagon towarowy - tor testowy). Uzyskane wyniki pozwoliły określić stan zagrożenia bezpieczeństwa ruchu wagonu towarowego przy różnych kryteriach oceny oraz je porównać.

współczynnik wykolejenia, dynamiki pojazdów szynowych, bezpieczeństwo, badania eksperymentalne

Artykuł dotyczy analizy nowo zdiagnozowanej przyczyny zużycia profili kół wagonu towarowego. W pracy przybliżono możliwe przyczyny nierównomiernego zużycia kół zestawów kołowych w wagonach towarowych znane z literatury, jak również podano nową hipotezę. Nowa rozpatrywana w pracy przyczyna nadmiernego zużycia kół zestawów kołowych dotyczy nieprawidłowej ich orientacji względem ramy wózka. Sytuację taką zdiagnozowano w wagonach towarowych posadowionych na wózkach z rodziny Y25, w wyniku niepoprawnego procesu naprawy ramy wózka i regeneracji maźnic. W pracy przedstawiono wyniki pomiarów przeprowadzonych na rzeczywistym wagonie towarowym oraz identyfikację zużyć i geometrii elementów pojazdu. W celu ilościowej analizy wpływu niepoprawnie zorientowanych osi zestawów kołowych na wielkość zużycia kół powstał model numeryczny, opisujący dynamikę ww. wagonu towarowego. Obliczenia numeryczne przeprowadzono przy różnych scenariuszach prędkości i geometrii toru oraz kilku wariantach zukosowania zestawów kołowych. Otrzymane z badań numerycznych wyniki wykazały istotny wpływ nierównoległości osi zestawów kołowych na nierównomierne zużycie profili kół. Zaprezentowana w pracy teza poparta wynikami badań może w znacznym stopniu wpłynąć na poprawę technologii wykonywania napraw układu biegowego oraz warunki utrzymania towarowego taboru kolejowego. Pozwoli także na redukując kosztów napraw zestawów kołowych i wydłużenie okresu ich eksploatacji.

zużycie kół, dynamiki pojazdów, badania numeryczne, transport towarowy

Praca zawiera omówienie wybranych zagadnień dynamicznych związanych z kinematycznym wymuszeniem od usterek toru wpływającym na degradację elementów pojazdów szynowych oraz rozwój uszkodzeń infrastruktury. Wskazano zjawiska, które mogą być przyczyną dużych obciążeń współdziałającego ze sobą układu pojazd-tor oraz zagrożenia wypadkami spowodowanymi zmęczeniem materiału elementów takiego układu. Podano przyczyny powstawania i rozwoju pęknięć szyn i osi zestawów kołowych. Przedstawiono przykłady badań doświadczalnych wskazujących na występowanie obciążeń dynamicznych znacznie przekraczających obciążenia statyczne spowodowane oddziaływaniem pojazdu i jego układu napędowego. Omówiono i zamieszczono w pracy wyniki badań teoretycznych uzyskanych z numerycznego modelu napędu pociągu z uwzględnieniem elektromechanicznych sprzęgnięć pomiędzy silnikiem a zestawem kołowym. Model ten pozwolił na analizę niekorzystych drgań skrętnych zestawu kołowego towarzyszących podczas przejazdu przez szczeliny w pojedynczym toku szynowym toru.
Prezentowane w pracy wyniki odniesiono do badań eksperymentalnych. W pracy przedstawiono również zagadnienia dynamiczne związane z samowzbudnością wskazujące na zjawiska, które mogą być przyczyną dużych obciążeń osi zestawów kołowych, jak również toru i ich degradacji oraz uszkodzeń zmęczeniowych tych osi. Zasygnalizowane zostały prawdopodobne przyczyny powstawania wielokrotnie większych od powszechnie uznawanych obciążeń szyn kołami kolejowymi. Podano kilka przykładów eksperymentalnego zbadania dynamicznego oddziaływania zestawów kołowych z torem będącego alternatywnym podejściem do kinematycznego wyjaśniania tego zjawiska.

drgania skrętne, uszkodzenia pojazdu i toru, dynamiki toru, badania numeryczne

The paper presents results obtained from experimental and simulation tests of trains, treated as simplified one-dimensional models of railway vehicles. This approach to train dynamics enables to assess train forces and their impact on dynamic characteristics, for example related to some problems of rapid starting or emergency braking. These works were used to implement them as a solver mechanism in the simulator of catenary maintenance trains, whose features in the article are discussed. In the paper algorithm of operating vehicles by their drivers in different driving scenarios are presents. The algorithm described simulator must meet atypical requirements resulting from the specific properties of the simulated vehicles.The paper describes also the methodology of identifying driving system of modeled vehicles and the way of adaptation of parameters obtained experimentally. Then, in brief, issues related to the image animation and presentation in the simulator are discussed. Also the most important rules of operating rail vehicle simulator, selecting proper scenarios and using effective training methods are characterised. Results of operational and numerical tests presented in the paper reflect in details processes accompanying the operation of catenary maintenance trains. The experimental test methodology to the real railway vehicles to acquire some missing work parameters was allowed. Results of the presented research indicate a large convergence of theoretical results with the experiment.The obtained result allowed to validate the work of the simulator

training simulator, dynamics of the train, experimental test, VBS3 environmental

In the paper, a dynamic electromechanical interaction between the wheelset of railway vehicle and its driving electric motors is investigated. This is the high-speed train driven by the electric motors through elastic hollow shaft with linear characteristics. In particular, there is considered an influence of negative electromagnetic damping generated by the motor on a possibility of excitation of resonant torsional vibrations. Conclusions drawn from the computational results can be very useful during a design phase of these devices as well as helpful for their users during a regular maintenance.

electromechanical coupling, torsion oscilation, electric motor, high speed train drive

Pracę poświęcono eksperymentalnym i numerycznym badaniom dotyczącym występowania gorących punktów w elementach hamulców tarczowych stosowanego w pojazdach szynowych dużej prędkości. W pracy zaprezentowano wyniki eksperymentalnych badań przeprowadzone na rzeczywistym układzie hamulcowym dedykowanym do takich pojazdów. W badaniach eksperymentalnych wykorzystano technikę termografii w podczerwieni, która pozwoliła scharakteryzować omawiane zjawiska cieplne. Uzyskane wyniki badań doświadczanych potwierdzono analizami numerycznymi, przy wykorzystaniu z walidowanego modelu układu hamulcowego. Wykorzystano w tym celu metodę elementów skończonych. Otrzymane wyniki numeryczne ilustrują zjawisko powstawania gorących obszarów na powierzchni tarczy hamulcowej wywołane przez termoelastyczne zaburzenia występujące na jej powierzchni.

gorące obszary, badania numeryczne, badania eksperymentalne, układ hamulcowy, pociągi dużych prędkości

Due to the fact that training simulators of railway vehicles must fulfill unique requirements resulting from the specific properties of the simulated vehicles, in this article on determining the main criteria for modeling the dynamics of such systems was presented. A methodology used in the study on the selection of parameters of the modeled vehicle and its driveline based on experimental studies was described. Adaptation of parameters obtained from the experimentally test into the dynamics model of vehicle was presented. Currently used solutions in simulators as well as issues related to animation and presentation of the image was provided. The requirements for the operation of the rail vehicle simulator, as well the design requirements for visualization of the image were defined and discussed.

railway vehicle simulator, railway vehicle drive system, virtual environment VBS3

A braking systems during friction interaction convert mechanical energy into heat energy. The corresponding heating is a major design parameter as it influences the tribological and mechanical performances (wear of the materials, friction performances, risks of cracks, vibrations, etc.). During breaking process in such breaking systems, different locations of thermal overheating areas of material of friction pair may occur, usually named as hot spots or hot bands. These spot and bands are characterized by very high temperature gradients. This brake systems exposed to thermoelastic instabilities show a characteristic temperature distribution on break disc surface that can lead to local material change. The interaction of thermal energy and thermal expansion of the material of the friction braking effect on the local increase in temperature leading to a dominant impact frictional forces in this area. Often destabilization of the braking process is a consequence of such a rise in temperature. The difficulty of understanding and modeling all of these phenomena still remains due to the complex interactions of thermal, mechanical, and tribological effects. Experimental investigation is still nowadays a major instrument for detecting and understanding the physical effects. In this presentation, we propose to consider an example

braking system, hot spots, hot bands, braking tests, infrared testing

Aiming at the torsional vibration in the electromechanical driveline system for railway trains, this article introduces a stability analysis of the drive system with electromechanically coupling. For a reliability and security of drive system of railway vehicles drive by electric motors, the electromagnetic output traction force and torques should drive stably, otherwise the shaft train vibration caused by motor torque ripple will affect the fatigue life of the device and the operation security of the driven object. For this reason an investigation of the dynamic response and stability of a electromechanical drive train system was done. For this purpose a dynamic model integrated with an electric motor to simulate the vibration in the component parts of the drive system were created. Such an approach for modelling of the considered electrical drive systems coupled with elements of a driven vehicle is particularly important when the purpose of such modelling is to obtain an information about the transient phenomena of system operation

electromechanical coupling, electric drive, electric motor, torsion vibrations, railway drive

The aim of this paper is to present a novel adaptive technique of control of the vibrating drilling systems. The algorithm constitutes an adaptive linear quadratic regulator that uses direct measurements of the disturbance to synthesize its linear dynamic approximation. This approach allows generating control law that includes the impact of the friction on the system dynamics and optimally steers the system to the desired trajectory. The effectiveness of the algorithm is validated via comprehensive numerical simulations of the control of the simplified drilling model. The results are compared to these obtained with the use of the Linear Quadratic Gaussian regulator.

vibration control, drillstring, adaptive control, auto-regressive model

The cost of maintenance, the reliability and the safety of railway operation depend strongly on the quality of the wheelsets and driving systems. Deformations and mechanical vibrations are phenomena associated with a functioning of majority of railway vehicle drivetrain structures. The time dependent variation of the contact forces between the wheels and the rails is highest importance, as sources of a torsion vibration in the systems. The knowledge about torsional vibrations in drive transmission systems of railway vehicles is of a great importance in the fields dynamics and fatigue of the mechanical systems. An electromechanical model of the railway vehicle drive system has been presented in the work. The values of electrical parameter characterizing the driving motor obtained from electric motor model have been used for determine the amounts of electric energy consumed by self-excited torsional vibration in the wheelset drivetrain system.

electric motor, cost of maintenance, electromechanical model, torsion vibration

In the paper presents experimental studies the influence of the formation of the hot spots on a brake disc. The heat produced in the brake system often leads to the appearance of hot spots on the surfaces of friction pairs during rapid braking. Nature and extent of the intensity of the phenomenon depends greatly on the mechanical and thermal properties of these friction pair materials. The temperature distribution in the elements analyzed systems friction affects their thermal deformation, initiating the above phenomenon. Shown in the work of the results of tests and analyzes the formation of the hot bands and the hot spots on the brake discs used in high-speed railway vehicles, provided information on the temperature distribution on the surface. One of the consequences of such a process is the increased wear and reduce the coefficient of friction. Measurements of the hardness of the hot bands and surface roughness of brake discs showed the effects of such phenomena on the change on the structure of the cast iron and steel discs materials. An increase the hardness of this hot area on the discs surface of may result in increased maintenance costs. The costs caused by for a more frequent lathing of the brake discs can occur. These changes also influences to reduce the coefficient of friction in the friction pair.

hotspot, maintenance costs, friction, infrared thermography, thermal coupling

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.

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

The analysis of stability the pipe with electromagnetic coupling in active elements has been done. Application of electromagnetic actuators leads to an increase in the critical flow velocity.The frequency of self-excited vibrations can either change with the volt-age supplied depending on the position of the active elements.

Flutter vibrations, electromagnetic coupling, electromagnetic actuators, EM damper of motional type

The analysis of stability the High Speed Train traction drive with electromechanical coupling has been done. Using the energy balance of the natural modes of vibration for the model of the drive system leads to determining the influence of electromagnetic parameters on its stability in relation to self-excited vibrations induced by friction.

electromechanical coupling, high speed train, stability analizys, synchronous motor

To ensure a reliability and unconditional security of drive system of machine and railway vehicles drive by electric motors, the electromagnetic output traction force and torques should drive stably, otherwise the shaft train vibration caused by motor torque ripple will affect the fatigue life of the device and the operation security of the driven object. For this reason an investigation of the dynamic response and stability of a electromechanical drive train system was done. The obtained results have demonstrated that the electromagnetic transient processes generated in the electric motor should be taken into account for the use of the assessing the stability of the system. The knowledge about stability of drive transmission systems of machines and railway vehicles is of a great importance in the field of dynamics and material fatigue of the mechanical systems.

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

A dynamic modelling of the electrical drive systems coupled with elements of a driven machine or vehicle is particularly important when the purpose of such modelling is to obtain an information about the transient phenomena of system operation, like a run-up, run-down and loss of adhesion in the wheel-rail zone. In this paper most attention is paid to the modelling of an electromechanical interaction between the electric driving motor and the railway wheelset. The knowledge about torsional vibrations in transmission systems of a high speed train (HST) is of a great importance in the fields dynamics of mechanical systems. Torsional vibrations in the railway vehicle drive train are generated by two main phenomena. To the first one belongs the electromechanical interaction between of the railway drive system including the: electric motor, gears, the driven part of disc clutch and driving parts of the gear clutch. To the second one belong torsional vibrations of the flexible wheels and wheelsets caused by variation of adhesion forces in the wheel-rail contact zone.

high speed train drive, electromechanical coupling, wheel-rail adhesion, asynchronous motor, electric motor

Thermoelastic instabilities are typically observed in frictional systems, which transform large quantity of kinetic energy into thermal energy. To this group we can include a high speed train brake system. This brake systems exposed to thermoelastic instabilities show a characteristic temperature distribution on break disc surface that can lead to local material change, vibrations of the braking system element coefficient of friction fluctuations. When reaching a critical sliding velocity, experiments show a nonhomogeneous and often periodic temperature distribution on the sliding surface. The mechanism of the phenomenon is caused by the interaction of heat generation and thermal expansion. A local rise in surface temperature results in a thermal expansion of the material nearby. Such a region of elevated temperature therefore is slightly higher than the surrounding topography and therefore carries a dominating part of the frictional load. A following rise in heat can destabilize the process. Two basic forms of thermoelastic instabilities can be commonly observed such as hot spots and hot bands.

high speed train braking, infrared technology, hot spotting, hot banding, brake disc, heat transfer

The heat produced between friction couple during braking induces thermal distortion in the disc and leads to appearance of hot bands. The Hot bands are generated by thermoelastic phenomena appearing in systems with high energy dissipation like brake or clutch systems. Systems exposed to thermoelastic instabilities show a characteristic temperature distribution that can lead to local material change, vibrations of the braking system element or coefficient of friction fluctuations. In the framework of studies there are presented results of experimental investigation on influence of the hot bands on properties of friction pair elements and parameters of the high-speed train brake system.

heat produced, friction coupling, breaking, hot bands, thermoelastic phenomena, friction fluctuations

In the framework of studies there are presented results of numerical investigation of the electromechanical drive system of the railway vehicle. Here, electric parameters of the asynchronous motor are rated to condition monitoring of the drive. Evaluation of the parameters can be used to create guidelines to a monitoring system. Main informations about a torsional vibration of wheelsets generated by friction coefficient in wheel-rail zone are provided by electric parameters obtained from a dynamic electromechanical drive model. The vibrations of wheelsets generated by a self-excited vibration mechanism of wheel-rail contact systems is very harmful. Proposed approach is alternative solution for monitoring of the torsion vibration in considered driving system. Results of this analysis can be used in order to investigate the drive system’s sensitivity to torsional oscillations.

condition monitoring, electromechanical coupling, wheel-rail adhesion, wheelset drivetrain dynamic

Magnetorheological materials are commonly used in technical devices because of specific behaviour in magnetic field. The magnetoactive particles are immersed in the carried fluid. The material becomes solid under the influence of magnetic field. The structure of solid material consists of the chains of the particles lying along the direction of magnetic field and the material under the stress is deforming as a solid body. The present studies are focused on the microscopic and phenomenological models of non-newtonian fluid. However, the mechanisms of deformation in solidified material under magnetic field require further investigations. The aim of the paper is to present the experimental visualization of the rearrangements of the particles in the activated by magnetic field chains. Basing on microscopic observations, the hypothesis is formulated that the mechanism of micro-shear banding is responsible for inelastic deformation of magnetorheological material. The discussed physical model makes the basis of the material description within the framework of the Perzyna viscoplasticity theory.

magnetorheological fluid, magnetorheological gel, Perzyna viscoplastic model