DIAGNOSTYKA Vol. 17, No. 2 (2016)
Table of contents - SCIENTIFIC PAPERS
Jacek LACHOWICZ, Magdalena RUCKA
Pages : 3-8

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Abstract (EN)
The paper presents a study on the use of the ground penetrating radar (GPR) method in diagnostics
of a footbridge. It contains experimental investigations and numerical analyses of the electromagnetic
field propagation using the finite difference time domain method (FDTD). The object of research was a reinforced concrete footbridge over a railway line. The calculations of the GPR field propagation were performed on a selected cross-section of the bridge. Three different damage scenarios (i.e. one missing rebar and two air voids with different shapes and locations) were investigated in FDTD simulations. Numerical GPR maps were compared with results of in-situ GPR surveys for the healthy footbridge.

Pages : 9-16

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Abstract (EN)
Computer simulations are currently often utilized tools in vehicle design, diagnostics of vehicle behaviour and evaluation of their characteristics. The vehicle multibody system (MBS) represents a complicated mechanical system especially when flexible bodies are considered, modelled and implemented in the calculation. Multibody system dynamics is based on classical mechanics and its engineering applications range from mechanisms, through means of transport, to biomechanics. Results of multibody system dynamics are most important for an assessment and diagnostics of transport means behaviour even in the development phase. This paper deals with the multibody system dynamic approach and its application in vehicle multibody systems. The first part of this paper focuses on a general approach to the multibody system of vehicles, especially of rail vehicles, and it includes fundamentals of multibody system dynamics. The next part deals with practical use of multibody system software. A multibody system of a passenger car have been modelled using commercial software, we have carried out simulations of a passenger car running on the real track, and subsequently we assessed its ride properties and evaluated its passenger comfort level.

Łukasz BREŃKACZ, Grzegorz ŻYWICA, Małgorzata BOGULICZ
Pages : 17-23

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Abstract (EN)

Piotr MROZ, Piotr GORNY, Martyna EKIERT, Tadeusz UHL
Pages : 25-34

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Abstract (EN)
In this paper we present a study on Li-Ion Battery (LIB) modelling, including battery ageing profile, as a ground for development of state of health (SoH) prediction and monitoring system. An influence of LIB ageing was included by the mean of ageing module, based on voltage, resistance and capacity characteristics, resulting from preliminary experimental measurements. Our model, based on equivalent circuit model (ECM) and parameter estimation procedure, was implemented in MATLAB software and then validated. The simulation results are used for battery SoH estimation, which may be use in a future to optimize the conditions of LIB cycling and therefore extend the battery lifetime. 

Pages : 35-41

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Abstract (EN)
Couplings incorporating rubber-cord shells, and their viscoelastic characteristics have been studied. The effectiveness of the couplings to limit the dynamic load is shown by an example of aballmill drive. It has been found that the use of the couplings equipped withrubber-cord shells as the flexible elements allows limiting the dynamic shock loads in machinedrives. It has been shown that the elimination of resonance modes and restriction of forced torque fluctuations in the drive can be providedby selecting a limit torque for the coupling actuation, which is determined by an initial air pressure in the rubber-cord shells of the coupling.

Pages : 43-48

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Abstract (EN)

All objects whose temperature is above absolute zero emit infrared radiation in the wavelength range of 740 nm to 1 mm. This range is between radio waves and visible light. This phenomenon related to thermal radiation is used in thermal imaging methods to measure values and distribution of temperatures on an inspected object.

Thermal imaging method was also used to inspect a two-stage gear system from a power transmission system of a belt conveyor located in an underground mine. Performing repairs in favorable time or preparing for failures contributes to the shortening of standstill periods and therefore to the minimizing of financial losses caused by purchasing replacement parts and unintended emergency stops.

Processing of thermograms was done with the use of ThermoVision Processing software, which was designed at Machinery Systems Division, Wroclaw University of Technology, in particular for thermal imaging diagnostics of gear systems. The software automatically identifies gear-wheels and divides the gear system into predefined areas – Ar01 to Ar10. It allows for processing single files and whole folders.

The inspection allowed to create object characteristics and specify its temperatures during steady work, which will serve as point of reference when the inspection is repeated at intervals of approximately several months. As a result, significant changes of the gear’s condition will become detectable, by calculating the difference between average temperatures for each area at two measurements. Temperature measurements are possible not only on the gear system but also on the motor shaft and the drive drum shaft. In the future, creating an application that would enable processing images of those parts will allow for multidimensional analysis of belt conveyor power transmission systems.

Pages : 49-55

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Abstract (EN)
The electronic safety systems are systems, the aim of which is to detect threats in the transport process
– for stationary and moving objects. These systems are increasingly being used in the transport process, where they provide safety – to people as well as goods transported in the stationary and moving objects. These systems operate in a diverse electromagnetic environment. The paper presents the research results of the electromagnetic interference impact on the electronic safety system with a structure of the control panels connected in parallel. The interference impact on selected operating parameters was presented for two frequency ranges, i.e. ELF (0
¸2) kHz and VLF (2¸100) kHz frequency ranges.

Krzysztof POPIOŁEK, Paweł PAWLIK
Pages : 57-64

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Abstract (EN)

This paper deals with the problem of diagnosing the technical condition of a planetary gearbox operating at variable load. The severity of the subject and related difficulties were discussed. Theoretical basis of analysis of non-stationary signals (order analysis) and its use in signal resampling was also presented.

The paper tests the functionality of the planetary gearbox diagnostics method. The Multilayer Perceptron Network was used to identify and classify the damage. The network’s learning vectors were built on the basis of order analysis results and measurements of the planetary gearbox load. The functionality of two-layer and three-layer unidirectional artificial neural network was also analysed for potential use in diagnosing the technical condition of planetary gears.

Arkadiusz RYCHLIK
Pages : 65-70

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Abstract (EN)
The aim of this study was to develop a non-invasive method for analyzing the technical condition of wheel rims in slow-moving vehicles. A vibration spectrum analysis was carried out in the frequency domain of wheel rims which were subjected to vibrations within a given range of parameters. Free vibration frequency and decrement in damping were determined to evaluate the rigidity and damping of the examined wheel rims. Those parameters were applied to evaluate weld joints, detect fatigue cracks and structural damage to the analyzed wheel rims. The proposed method can be used to inspect both brand new and used wheel rims in passenger cars, special purpose vehicles and slow moving vehicles. The developed method is non-invasive, and it does not cause damage to the tested object. The time required to perform measurement is will depend on the size of the wheel rim, but it should not exceed 20 seconds.

Pages : 71-80

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Abstract (EN)
Damage classification plays a crucial role in the process of management in nearly every branch of industry. In fact, is becomes equally important as damage detection, since it can provide information of malfunction severity and hence lead to improvement of a production or manufacturing process. Within this paper selected supervised and unsupervised pattern recognition methods are employed for this purpose. The attention of the authors is given to assessment of selection, performance benchmarking and applicability of selected pattern recognition methods. The investigation is performed on the data collected using an experimental test grid and rolling element bearing with deteriorating condition of an outer race.

Pages : 81-86

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Abstract (EN)
The paper deals with detection of hot spots in thermograms acquired during infrared inspections of power transmission lines. The author proposes an approach to automated selection of a threshold value for image segmentation using several methods of image processing and analysis. The algorithm is based on finding the steepest growth of successive gradients of sorted values of input image after certain image pre-processing steps. Several post-processing procedures were applied for proper visualization of detected regions in the resulting images. The results have brought satisfying effects and the algorithm, owing to its fast performance, could be also used on-line, during vision inspections.

Grzegorz ŻYWICA, Maciej KANIECKI
Pages : 87-94

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Abstract (EN)
The article demonstrates how to take advantage of modern measurement techniques and detect defects of different types. These techniques contributed to solve the unknown operating problem of a hydropower machine. The examined hydro set comprises a water turbine (of the Francis type), elastic coupling, flywheel and electro-generator. To assess the dynamical state of the machine and detect the reasons for elevated vibration level, the following diagnostic tests were carried out: precision measurement of vibration, laser shaft alignment check and thermal imaging tests. These three widely diverse measurement techniques complemented each other, allowing the identification of the cause of increased vibrations and taking countermeasures to make further operation possible. The article provides an example of the practical application of the currently available vibrodiagnostic methods for monitoring and assessment of the technical condition of fluid-flow machines.

Pages : 95-103

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Abstract (EN)
In this paper, the author analyzed an applicability of selected types of time-frequency distributions that belong to Cohen’s class and their reassignments for signals similar to those obtained during machinery diagnostics. At the first step of performed studies a synthetic multicomponent signal that contains both stationary and non-stationary components was analyzed using algorithms based on various time-frequency distributions. This allows for evaluating effectiveness of identification of particular components by applied time-frequency distributions and selecting a group of the most effective algorithms. At the second step, the selected time-frequency distributions were applied for analysis of signals acquired during diagnosis of rolling bearings in order to verify the effectiveness of identification of components responsible for a priori known faults occurred in bearings.