DIAGNOSTYKA Vol. 16, No. 4 (2015)
Table of contents - SCIENTIFIC PAPERS
Bernard FRYŚKOWSKI
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Abstract (EN)
The misfire effect in an automotive ignition circuits is caused by parasitic spark plug shunt resistance resulting in leakage current flow. The main explanation for leakage current flow through a spark plug insulator is insulator surface contamination or dielectric failure. Practical measurements show that the spark plug waveforms analysis could be used for diagnostic purposes to recognize the presence of shunt resistance in secondary ignition circuit. A novel method of leakage current simulation and a prototype of an adjustable ignition coil electric load able to operate at high – voltage were proposed. Energy dissipated by adjustable electric load, spark plug voltage and leakage current measurement results were presented. A change in the shape of spark plug voltage and current waveforms caused by leakage current was analyzed and discussed.

Krzysztof KOŁOWROCKI, Joanna SOSZYŃSKA-BUDNY
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Abstract (EN)
The paper is concerned with the methods and procedures for identification of unknown parameters of a general probability model of a complex technical system operation process and their practical application. The general multistate model of a complex technical system operation process is proposed and the procedure of identifying its basic unknown parameters is presented. There are also suggested typical distribution functions describing the system operation process conditional sojourn times at particular operation states and the procedure of identifying their unknown parameters is proposed. An illustration of the proposed methods and procedures practical application to identifying the port oil piping transportation system operation process and its operation characteristics prediction is presented.

Tetyana STEFANOVYCH, Serhiy SHCHERBOVSKYKH, Paweł DROŹDZIEL
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Abstract (EN)
In the paper reliability model for pressure vessel protective fittings is developed. The model is intended for the quantitative analysis of failure causes of such system. Reliability of the system is formalized by the dynamic fault tree in which load-sharing phenomena are mathematically described. Using the dynamic fault tree the split homogeneous Markov model is obtained. Reliability characteristics are calculated based on the Markov model. Life of protective fittings components is distributed by Weibull that provided by tensor splitting of Markov model. The result of the simulation is probability curve family obtained for different values of load-sharing coefficients. It is shown how the main cause of system failure changing with these coefficients changing.

Jarosław ZALEWSKI
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Abstract (EN)
In this paper a computer simulation of a frontal oblique collision between two motor vehicles was carried out, using the PC-Crash 8.0 software. The simulation repeated several times for specific values of the coefficient of restitution. Then the results were compared with analytical calculations, which were based on the planar collision mechanics, including the theory of collision between the bodies with smooth surfaces.
Analysis of the influence of the selected coefficient was made primarily in terms of change in the after crash vehicle speed. The aim of the study was to determine whether the value of the coefficient of restitution in a frontal impact play an important role in the analysis of the process of such phenomenon.

Michał OPYDO, Agata DUDEK, Grzegorz GOLAŃSKI, Paweł URBAŃCZYK
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Abstract (EN)
Energy market is the sector of the economy which has been given a lot of attention in the last decades. This results not only from a global increase in demand for energy but also from the needs for environmental protection. It should be also noted that modernization of the energy sector is capital-intensive. Therefore, the directions of development in this sector should be driven not only by ecological reasons but also by reasonable economic calculus based on in-depth analysis of operational costs in the next decades. For this reason, an important position in the structure of energy generation is taken by co-combustion of various fuels, with particular focus on coal and biomass. Co-combustion of fuel mixtures, with each fuel having varied properties, often accelerates degradation of the structural components of a boiler.

Krzysztof SZCZUROWSKI, Stanisław RADKOWSKI, Damian WALCZAK, Michał TROJGO Łukasz ZIELIŃSKI
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Abstract (EN)
This article presents methods of acquisition of information from vehicle electronic components, with the purpose of its use to control the additional devices. These additional devices can comprise an LPG fitting, which was installed on a tested vehicle. Also, the way of modifying the contents of the engine control unit has been shown in order to examine the influence of the serial settings of the injection timing. Information that can be obtained from the CAN (Controller Area Network) allow for the lack of interference with the original manufacturer wiring, not disturbing the analogue signals at the same time. Modification of controller memory contents enables the improvement of performance parameters, especially in the case of the compression-ignition engine being fuelled with the addition of LPG. In the Summary section, the dynamometer test results of the modified vehicle have been presented. The tests were conducted for different control parameters during powering with Diesel fuel exclusively, as well as with the addition of LPG.

Tadeusz DĄBROWSKI, Wiktor OLCHOWIK, Sławomir AUGUSTYN
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Abstract (EN)
This paper is devoted to deliberations on transmittance measurement system properties and potential Pilot-Helicopter-Environment (P-H-E), in the security context of this system. Based on the operator’s transmission of the Pilot-Helicopter (P-H) and the results of the stability studies, it is possible to obtain the answer about the scope of acceptable - for safety reasons - changes the operator’s transmission coefficients. On the other hand, the potential recognition allows the inference about the properties of the P-H-E system in safety and reliability areas. The basis of this interference is the assumption concerning the system which is suitable for the safe implementation of tasks in certain conditions and if the P-H system has a required stability supply at the specified time.

Mirosław SIERGIEJCZYK, Adam ROSIŃSKI
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Abstract (EN)
Intelligent transport systems usually operate in diversified working conditions. As elements participating in the transport process, they should keep their usability. That is why the elaborations in the scope of ensuring proper values and indices of reliability and operation are so important. The article presents issues regarding monitoring of the fibre optic cable teletransmission track of the highway emergency response system. The overriding goal is to aim for maintaining a usability state for that transmission medium.

Piotr BIAŁKOWSKI, Bogusław KRĘŻEL
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Abstract (EN)

In this article an early crack detection method during fatigue testing has been described. The test object was a beam mounted on a durability test bench. Piezoelectric accelerometers were mounted onto the beam. With observation of the signals from the accelerometers it was determined what change of the signal was caused by crack appearance during the test. Three car beams were tested. The measurement method and testing bench are described in this work.

To determine the change of the signal and show potential cracks, time domain estimates have been used: RMS, peak, peak-peak, Crest Factor and Kurtosis. Results for all these estimates are listed in tables. Conclusions were drawn according to their variations  in particular time ranges.


Martyna EKIERT, Andrzej MLYNIEC, Tadeusz UHL
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Abstract (EN)
In this paper, we present a study on stability of popular biopolymer poly(lactide acid) (PLA) under degradation process. As a main objective of this study we investigate an influence of polymer decomposition on decrease of its two physicochemical parameters – dynamic viscosity and molecular mass. To include the molar mass distribution we calculate three various mass averages: the number, the weight and the viscosity molar mass. To simulate the polylactide behavior at the atomic level we use molecular dynamics method in conjunction with reactive force field ReaxFF. To provide degradation conditions similar to human interior system we operate in the MD-NVT conditions at the temperature 310K. Based on reported in literature values of polylactide density we develop computational model of its amorphous structure. We achieve full compliance with expectations – obtained values of PLA viscosity and mass are steadily dropping. Determined trends confirm progressive polymer decomposition resulting in deterioration of polymer durability. The obtained results may be use in a future to predict a lifetime of biomedical polymer implants.

Leonid POLISHCHUK, Orest BILYY, Yevhen KHARCHENKO
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Abstract (EN)
The problem of assessment of main carrying elements (belts) of clamp-forming machine boom made of the angle 45×45×5 mm (Steel 3) in the process of diagnostics is considered. The fragment of the belt is modelled by means of a plate, hawing the crack with typical sizes. Analytical relations are given, stresses intensity factors (SIF) K1 and rates of their change dK1/da near the apex of a crack are investigated. Six cases of potentially possible crack-like defects initiation are considered, criteria lengths of cracks are determined for them, proceeding from the obtained experimental data.

Marcin FIRLA, Timothée GERBER, Pascal BELLEMAIN, Nadine MARTIN
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Abstract (EN)
This paper proposes an advanced signal-processing technique to improve the condition monitoring of rotating machinery. The proposed method employs the results of a blind spectrum interpretation including harmonic and sideband series detection. The contribution of this paper is an algorithm for automatic association of harmonic and sideband series with the characteristic fault frequencies listed in the kinematic configuration of the monitored system. The proposed algorithm is efficient in inspection of real-world signals, which contain a vast number of detected spectral components. The proposed approach has the advantage of taking into account a possible slip of the rolling-element bearings. The performance of the proposed algorithm is illustrated on real-world data by investigating a shaft problem of an industrial wind turbine high-speed shaft.