DIAGNOSTYKA Vol. 18, No. 2 (2017)
Table of contents - SCIENTIFIC PAPERS
Boulanouar SAADAT, Abdellah KOUZOU, Mouloud GUEMANA, Ahmed HAFAIFA
Pages : 3-11

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Abstract (EN)

The present paper deals mainly with the improvement of the degradation indicators of a gas turbine. Therefore, to achieve this purpose a prognostic approach is used in order to provide an adequate diagnostic function of the studied gas turbine.  In this context, this paper proposes a degradation modeling of the studied gas turbine system in order to increase its safety and to ensure accurate future decision making process that allow to enhance the operating state of this industrial equipment. Indeed, the prognostic system proposed in this work takes into account the eventual vibration impacts over all phases of the life cycle process of the studied system to provide a diagnostic function with the required availability at with lowest maintenance cost.


Ahmed ADRI, Rhali BENAMAR
Pages : 13-21

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Abstract (EN)

In the present paper, the frequencies and mode shapes of a clamped beam carrying a point mass, located at different positions, are investigated analytically and a parametric study is performed. The dynamic equation is written at two intervals of the beam span with the appropriate end and continuity conditions. After the necessary algebraic transformations, the generalised transcendental frequency equation is solved iteratively using the Newton Raphson method. Once the corresponding program is implemented, investigations are made of the changes in the beam frequencies and mode shapes for many values of the mass and mass location.   Numerical results and plots are given for the clamped beam first and second frequencies and mode shapes corresponding to various added mass positions. The effect of the geometrical non-linearity is then examined using a single mode approach in order to obtain the corresponding backbone curves giving the amplitude dependent non-linear frequencies.


Janusz ZACHWIEJA
Pages : 23-30

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Abstract (EN)

The pipelines are subject to various constraints variable in time. Those vibrations may result in both the fatigue damage in the pipeline profile at high stress concentration and the damage to the pipeline supports. If the constraint forces are known, the system response may be determined with high accuracy using analytical or numerical methods. In most cases, it may be difficult to determine the constraint parameters, since the industrial pipeline vibrations are due to the dynamic effects of the medium in the pipeline. In that case, a vibration analysis is a suitable alternative method to determine the stress strain state in the pipeline profile. If a straight pipe section supported on both ends is excited by the bending moments in the support profile, the starting point for the stress analysis are the strains, determined from the Euler–Bernoulli equation. In practice, it is easier to determine the displacement using the experimental methods, since the factors causing vibrations are unknown. The industrial system pipelines, unlike the transfer pipelines, are straight sections at some points only, which makes it more difficult to formulate the equation of motion. In those cases, numerical methods can be used to determine stresses using the kinematic inputs at a known vibration velocity amplitude and frequency. The study presents the method to determine the stresses.


Beata ZIMA, Magdalena RUCKA
Pages : 31-36

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Abstract (EN)

The paper presents an experimental investigation of elastic wave propagation in a self-drilling hollow bar system, which is commonly used in geotechnical industry as the element of grouted ground anchors and soil nails. The single self-drilling hollow bar and self-drilling system of two bars connected by a coupler were considered. Longitudinal waves were excited at one end of the bar and registered at both ends, by means of PZT plate transducers. Additionally, in the case of connected bars, the transducer was also located at the coupler. The main aim of the study was to analyse the wave attenuation because of discontinuities in the form of mounting connections occurring along the bar length. The differences in wave propagation signals registered at single bar and the system of two bars were indicated and discussed.


Andrzej GRZĄDZIELA, Marcin KLUCZYK
Pages : 37-42

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Abstract (EN)

In recent years, diagnostics of marine reciprocating engines devote more and more attention. In principle, all methods for the diagnostics of marine engines can be divided into based on the measurement of work parameters (mostly changes in internal cylinder pressure), and measuring the residual energy. For this study the authors focused on the measurement of vibration parameters and their analyzes. Acceleration of vibration measurements was carried out on the engine head. During the tests, fatigues to the injection installation were simulated, it had affected to the value and the course of the gas pressure inside the cylinders. The results of research proving the usefulness of the proposed method.


Olena GUMEN, Nadiia SPODYNIUK, Malgorzata ULEWICZ, Yevgen MARTYN
Pages : 43-49

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Abstract (EN)

The article presents the results of experimental research of thermal processes in industrial premises with energy-saving technologies of heating and their analysis by geometric modeling tools and graphic computer technologies. The effectiveness of using the method of forced feeding of air heated by infrared emitter involving compromise graphical optimization was analyzed by geometric way.


Tomasz Zygmunt KACZMARCZYK, Grzegorz ŻYWICA, Eugeniusz IHNATOWICZ
Pages : 51-58

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Abstract (EN)

This paper presents results concerning the experimental investigation of a five-stage prototypical
axial-flow microturbine operating in an ORC installation. The microturbine has an electrical capacity of 3 kW at the nominal rotational speed of 12000 rpm and is supplied with a low-boiling medium's vapour HFE7100. During the test, both the full vibration frequency distribution and the overall level of the velocity vibrations RMS in the microturbine were measured. A spectral analysis of vibration velocity was conducted during the grind-in process after a modernisation of the shrouding bandage of the microturbine set's flow system took place. The article presents the operational characteristics of the ORC system as well as the characteristics showing the electric power produced as the function of rotational speed of the microturbine. On the basis of the results obtained, there was assessed the dynamic performance of the microturbine and it was ranked according to ISO 10816-1 standard. The paper also shows the measurement results of the so-called kurtosis within the frequency range of 15 to 30 kHz, which made it possible to evaluate the dynamic state of the rolling bearings by which the microturbine rotor was supported.


Ján PETRÓCI, Martin MANTIČ, Oskár SLOBODA
Pages : 59-64

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Abstract (EN)

The paper deals with the analysis of power loss involved in an experimental single-cylinder internal combustion engine during its operation. The experimental engine has been developed and built entirely at the University for the purposes of Shell Eco-marathon. A series of experimental measurements was taken to discover the reasons for the issues we had encountered by obtaining output power characteristics and the value of compression pressure regularly at specific intervals. The data we obtained served to diagnose faults and to propose solutions for their elimination.


Piotr LESIAK, Aleksander SOKOŁOWSKI, Marek WLAZŁO
Pages : 65-73

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Abstract (EN)

The cross-correlation function has been applied to the study of the similarity of the two functions. One of these functions is known and represents a defect type HC (Head Checking) in the railway rail. The second function is unknown and based on cross-correlation function of both functions specifies the parameters of the similarities. These functions correspond to defects whose images have been determined using laser scatterometry method. FFT method has been used to calculate these functions.  


Andrzej GĘBURA, Michał STEFANIUK
Pages : 75-85

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Abstract (EN)

Dynamics of the helicopter rotor (blade vibrations, ground resonance, influence of forward speed etc.) plays a significant role in wear of transmission and engine systems. Particularly severe wear of these elements can be expected on military helicopters operating in battlefield conditions, where exceedances of dynamic flight parameters and harsh maneuvers occur more frequently. The “FAM-C” diagnostic method, developed by the Air Force Institute of Technology in Poland, has been used for assessing and monitoring a fatigue wear. Particularly, this method may be applied to monitor defects of power plant and helicopter transmission system, where other “classical” methods are less efficient due to the very complex variable system as for the direction and frequency, system of forces generating vibrations in kinematic pairs situated close to each other. Due to this reasons certain vibroacoustic and thermal effects develop around these pairs and they interfere with each other. In a helicopter, a power plant, including a power transmission system is also a carrying assembly. It forced designers to construct a power plant with increased number of joints and bearing supports. This article depicts possibilities of FAM-C method regarding wear of the main bearing of helicopter rotor, wear of surface of teeth contact, clearances between axles of gear wheels in gear and the evaluation of circumferential clearances on splined connections. In the FAM-C method, signal from the AC generator used in routine operation of the helicopter is processed. Signal analysis enables simultaneous monitoring of several engine and transmission elements at the same time. It doesn’t require any separate sensors – one permanent electric generator or tachometer generator is – by the appropriate way of picking up and converting the output voltage signal – a source of the whole gamut of diagnostic information.


Mirosław SIERGIEJCZYK, Michał KOZŁOWSKI, Ewa DUDEK
Pages : 87-93

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Abstract (EN)

The influence of potentially erroneous, incomplete or inaccessible aeronautical data and information on the occurrence of an accident or serious incident in air traffic and transport is enormous. Those data and information quality has a direct impact on flight operations’ safety. Moreover, much of the information provided, is the basis for planning and safe conduct of the flight and is used to achieve safety, regularity and efficiency of Air Traffic Management, so they must always be up to date and ready to use. In this paper the aeronautical data chain, described in one of the Eurocontrol specifications, was analysed. Then a proceeding diagram, compliant with holding true requirements, was elaborated, pointing out its weaknesses in terms of diagnosis of potential non-compliance that may occur during data request, origination, evaluation, preparation, distribution as well as its end use. In order to facilitate the detection of potential errors, diagnostics of potential incompatibilities’ effects and causes the risk analysis using FMEA method was conducted, giving as an output a rating of non-compliance importance based on the risk priority number (RPN).


Michał KURPIŃSKI, Marek FIDALI
Pages : 95-103

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Abstract (EN)

Adhesive bonded joints are one of the most popular type of joints in the production process of modern cars. That came from their uncommonly good features i.e. durability, visual and economical properties. However, during the production process some defects can occur. There are many Non-Destructive Testing (NDT) methods which allow detection of different defects of adhesive joints and increase the quality of the production process as well as the produced part. In the first part of the article, a review of the most valuable NDT methods was presented, especially from the point of view of application to automated testing of automotive parts. In the second part, two contactless NDT methods (EMAT ultrasonic technology and active thermography) were applied to prepared bonded joints. Results of preliminary laboratory tests were compared. The aim of the research was to point out the most suitable method for industrial application.