Wyniki wyszukiwania - BazTech

1

Determination of dynamic parameters of a tram wheel parts in a numerical and experimental modal analysis

Milewicz Julia, Kołodziejczak Krzysztof, Nowakowski Tomasz, Szymański Grzegorz M.

Archives of Transport

|

2023

|

Vol. 67, iss. 3

119--137

EN

The analysis of dynamic parameters finds effective application in processes related to the assessment of the technical condition of machines. Mass transport vehicles are particularly sensitive to maintaining an appropriate level of traffic safety through relevant design and diagnostics. The combination of numerical and experimental methods increases the efficiency of modal properties investigations, which can be used as diagnostic parameters. During the research, the authors performed a numerical model of a system composed of a rim and an inner disc of a wheel fitted in a Konstal 105Na tram, widely used in many polish cities and frequently subjected to repair and renovation processes. The Time Response analysis in SOLIDWORKS (also called Modal Time History) was then conducted, resulting in obtaining information about object vibration response in time domain to the impulsive excitation at given points. These signals were then processed in MATLAB aiming at determining the frequencies of natural vibration and damping ratios. The processing parameters in MATLAB were corresponding to the analysis settings of the experimental measurement, carried out within the BK Connect environment, with an impact modal hammer and piezoelectric transducers. When analyzing the experimental measurements, the authors applied Fast Fourier Transformation, Frequency Response Function and Complex Mode Indicator Function (the theoretical basis of which and practical sense of application were also presented in the paper). Finally, the results of the experiment were compared with simulation outcomes. This comparison allowed the obtainment of frequency characteristics of the vibration response to the impact and the determination of the dynamic parameters of the actual object. Six frequencies of natural vibrations were determined in the frequency range of 0 to 3000 Hz, as well as their damping ratios and autocorrelation indicators between modes. Similarities and potential sources of differences between the numerical and the experimental results were identified and explained, followed by conclusions on the practical application of the presented research methodology in the industry.

2

Using the MIMO method to evaluate the modal properties of the elements of a wheelset in an active experiment

Milewicz Julia, Mokrzan Daniel, Nowakowski Tomasz, Szymański Grzegorz M.

Vibrations in Physical Systems

|

2022

|

Vol. 33, nr 3

art. no. 2022324

EN

The study of the system composed of the inner disc and wheel rim of the 105Na type railway wheel, used in Polish Konstal streetcars, was aimed at determining the dynamic parameters of the object, such as the form and frequency of natural vibrations, and at evaluating the effectiveness of the method at given analysis settings. The experiment was conducted using triaxial piezoelectric transducers and a modal hammer with an aluminum head. A multiple-input, multiple-output (MIMO) testing approach was used because of the multiple excitation points and vibration measurements. A Fast Fourier Transform (FFT) of the measurements was performed in BK Connect software and the frequency response function (FRF) value waveforms were determined. The Rational Fraction Polynomial-Z method was used to extract modes from the frequency spectrum. In addition, the Complex Mode Indicator Function method was used, which resulted in the decomposition of the principal components of the FRF value matrix, allowing the identification of individual modes. The selection of the natural frequencies was performed on the basis of the obtained FRF and CMIF characteristics of the vibroacoustic response. Visualization of the form of the natural vibration was also performed. The result of the experiment was a set of comprehensive information on the modal properties of the studied object, which allowed to confirm the effectiveness of the selected method of analysis.

3

Using vibroacoustic methods to describe the dynamic properties of composite elements to assess their technical condition

Mokrzan Daniel, Milewicz Julia, Szymański Grzegorz M.

Pojazdy Szynowe

|

2021

|

Nr 2

41--51

EN

The article presents the research process and a feasibility analysis of using acoustic pressure as a diagnostic parameter in technical condition assessment of elements made of composite materials. An experiment was carried out in the form of a pulse test using a modal hammer to induce the system's vibroacoustic response. Large internal defects in the structure have been shown to cause changes in the characteristics of the Frequency Response Function (FRF) in the band below 8 kHz. The conducted analysis was used to prove that acoustic pressure can be effectively used in the diagnosis of elements made of composite materials.

PL

W artykule zaprezentowano przebieg badań oraz analizę dotyczącą możliwości wykorzystania ciśnienia akustycznego jako parametru diagnostycznego w ocenie stanu technicznego elementów wykonanych z materiałów kompozytowych. Przeprowadzono eksperyment w postaci testu impulsowego z wykorzystaniem młotka modalnego jako wzbudnika odpowiedzi wibroakustycznej układu. Wykazano, że duże wewnętrzne ubytki w strukturze powodują zmiany charakterystyki funkcji odpowiedzi częstotliwościowej (Frequency Response Function, FRF) w paśmie poniżej 8 kHz. W wyniku przeprowadzonej analizy udowodniono, że ciśnienie akustyczne może być skutecznie wykorzystywane w diagnozie elementów wykonanych z materiałów kompozytowych.

4

Methods for reducing the number of collisions between wild animals and rail vehicles

Milewicz Julia, Mokrzan Daniel, Szymański Grzegorz M.

Pojazdy Szynowe

|

2021

|

Nr 3

30--43

EN

The article presents the issues of collisions between wild animals and approaching trains. The reasons for the presence of animals on the tracks are explained and the potential threats to the environment and the safety of railway traffic are described. In order to reduce the chance of an accident involving animals, the various solutions are used: infrastructure (making animals difficult to enter the tracks) and stimulus (warning against the approaching train) and supporting methods that may increase the effectiveness of other measures. The analysis of the results of research carried out in various ecosystems around the world allowed to assess the effectiveness of the most popular methods of protecting fauna against the collision with a vehicle and the innovative solutions, taking into account the psychology of animals. Their use will allow to reach a compromise between the development of transport networks, traffic safety and reduction of the impact on the natural environment.

PL

W artykule przedstawiono problematykę zderzeń dzikich zwierząt z nadjeżdżającymi pociągami. Wyjaśniono przyczyny obecności zwierząt na torowiskach i opisano potencjalne zagrożenia dla środowiska, jak i dla bezpieczeństwa ruchu kolejowego. W celu zmniejszenia zagrożenia wypadkiem z udziałem zwierząt stosuje się różne rozwiązania: infrastrukturalne (utrudniające wstęp zwierząt na tory) i bodźcowe (ostrzegające przed zbliżającym się pociągiem) oraz metody wspomagające, które mogą zwiększy skuteczność działania innych środków. Analiza wyników badań przeprowadzanych w różnych ekosystemach na całym świecie pozwoliła ocenić efektywność najpopularniejszych sposobów ochrony fauny przed zderzeniem z pojazdem oraz innowacyjnych rozwiązań, uwzględniających psychologię zwierząt. Zastosowanie ich pozwoli na osiągnięcie kompromisu pomiędzy rozwojem sieci transportowych, bezpieczeństwem ruchu i redukcją oddziaływania na środowisko naturalne.

5

Vibroacoustic analysis in the assessment of the technical condition of the aircraft airframe composite elements

Mokrzan Daniel, Milewicz Julia, Szymański Grzegorz M., Szrama Sławomir

Diagnostyka

|

2021

|

Vol. 22, No. 2

11--20

EN

The paper presents the method of assessment of the technical condition of the leading edge of the horizontal stabilizer of an F-16 Block C aircraft made from composite materials. The described method was an experimental measurement of the acoustic pressures generated by the technically operational element and the element with the distorted structural continuity and then a comparison of these pressures in the curves of time and frequency in order to assess how the damage impacts the parameters of the acoustic wave. The test was performed in a dual-channel system, the pressure was induced through impacts on the investigated element with an impact hammer and then, based on the measured induction parameters and the generated acoustic wave, the function of frequency response was calculated, based on which the authors assessed how the structural damage influenced the curve characteristics of the acoustic pressure in the domain of frequency. The described method may be used as an efficient method of non-destructive diagnostics of the airframe elements of an aircraft.

PL

Artykuł przedstawia metodę oceny stanu technicznego krawędzi natarcia statecznika poziomego statku powietrznego F-16 Block C wykonanej z materiałów kompozytowych. Opisywaną metodę stanowił eksperymentalny pomiar ciśnienia akustycznego emitowanego przez element sprawny technicznie oraz element z naruszoną ciągłością struktury, a następnie porównanie ich przebiegu w domenie czasu oraz częstotliwości celem ustalenia w jaki sposób uszkodzenia wpływają na parametry emitowanej fali akustycznej. Badanie dokonywane było dwukanałowo, ciśnienie akustyczne wzbudzane było za pomocą uderzeń w badany element za pomocą młotka modalnego, następnie na podstawie zmierzonych parametrów wzbudzania oraz wywołanego nim fali akustycznej obliczono funkcję odpowiedzi częstotliwości, na podstawie której określono jak uszkodzenie struktury wpływa na przebieg charakterystyki ciśnienia akustycznego w dziedzinie częstotliwości. Opisywana metoda może służyć za skuteczną metodę diagnostyki nieniszczącej elementów płatowca statku powietrznego.

6

The assessment of the technical condition of SO-3 engine turbine blades using an impulse test

Milewicz Julia, Mokrzan Daniel, Szymański Grzegorz M.

Combustion Engines

|

2021

|

R. 60, nr 1

24--29

EN

The paper presents the effects of the application of an experimental impulse test as a method of diagnosis of the technical condition of an SO-3 engine turbine blade fitted in a TS-11 Iskra aircraft. The aim of the test was to investigate the frequency characteristics of the blades and discuss differences between the frequency spectrum of the investigated component before and after its damage. The acoustic response measurements were performed to the signal generated by an impact hammer on the fully functional and intentionally damaged blades. The recorded signals were converted from the domain of time to the domain of frequency using the Fast Fourier Transform (FFT). The results of the FFT were the Frequency Response Functions (FRF) of the sound of the blades, based on which the statistical analysis of the resonance frequencies was carried out. The influence of the mechanical damage of the blade on the shape and characteristics of the frequency spectrum was confirmed, which substantiated the effectiveness of the impulse test in the diagnostic assessment of jet engine components.