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1
Content available Determination of rail vehicle speed with acoustic signal processed using continuous wavelet transform
Mokrzan Daniel, Nowakowski Tomasz, Szymański Grzegorz M.
Vibrations in Physical Systems
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2023
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Vol. 34, nr 2
art. no. 2023223
EN
The paper presents the course of research and analysis on the possibility of using time-frequency methods of acoustic signal processing to determine the speed of moving rail vehicles. An experiment was conducted in the form of a trackside pass-by test of the acoustic pressure emitted by passing trams representing the rolling stock of the Municipal Transport Company in Poznan. The recorded signal was then processed using the Continuous Wavelet Transform (CWT), resulting in a scalogram that is a variation of the time-frequency characteristics. This made it possible to identify in the signal the travel time of individual bogies and their wheelsets, as well as the most sensitive value of the scale parameter. The waveform of the scalogram fragment for the selected value of the scale parameter was processed using the RMS envelope, and then the peak values were identified. Juxtaposing the obtained results with the knowledge of the structural dimensions of the tested vehicle, it was possible to determine its moving speed. To validate the results of the experiment, photocells located on both sides of the measurement track were used, which generated voltage when the test vehicle passed between them, allowing the determination of its average moving speed. The result of the study was the formulation of a method that can be used to determine the speed of a vehicle based on the time elapsed between the identification in the signal of the components corresponding to the passage of successive sets of wheels.
2
Content available Estimation of fuel consumption in a jet engine based on vibration signal parameters
Szymański Grzegorz M., Cywka Bartłomiej, Mokrzan Daniel, Prokopowicz Wojciech
Combustion Engines
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2023
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R. 62, nr 3
13--20
EN
This paper proposes the use of vibroacoustic signal parameters to estimate the fuel consumption of a miniature GTM-400 engine. The method for testing engine vibrations is presented, followed by an analysis of the results obtained. Two vibration point measures were selected to build a fuel consumption model. The models obtained were verified, after which those that best describe the real fuel consumption of the engine were selected. The paper proves that the vibration signal, in addition to its applications in jet engine diagnostics, can be used to determine engine performance, which can contribute to reducing the complexity of construction and increasing the economics of engine operation.
3
Content available The application of time-frequency methods of acoustic signal processing in the diagnostics of tram drive components
Mokrzan Daniel, Nowakowski Tomasz, Szymański Grzegorz M.
Archives of Transport
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2023
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Vol. 68, iss. 4
55--75
EN
The paper presents the course of investigations and the analysis of the possibility of applying selected methods of time frequency processing of non-stationary acoustic signals in the assessment of the technical condition of tram drive components, as well as a new combined method proposed by the authors. An experiment was performed in the form of a pass-by test of the acoustic pressure generated by a Solaris Tramino S105p tram. A comparative analysis has been carried out for an efficient case and a case with damage to the traction gear of the third bogie in the form of broken gear teeth. The recorded signal was analyzed using short-time Fourier transform (STFT) and continuous wavelet transform (CWT). It was found that the gear failure causes an increase in the sound level generated by a given bogie for frequencies within the range of characteristic frequencies of the tested device. Due to the limitations associated with the fixed window resolution in STFT and the inability to directly translate scales to frequencies in CWT, it was found that these methods can be helpful in determining suspected damage, but are too imprecise and prone to errors when the parameters of both transforms are poorly chosen. A new CWT-Cepstrum method was proposed as a solution, using the wavelet transform as a pre-filter before cepstrum signal processing. With a sampling rate of 8192 Hz, a db6 mother wavelet, and a scale range of 1:200, the new method was found to infer the occurrence of damage in an interpretation-free manner. The results were validated on an independent pair of trams of the same model with identical damage and as a reference on a pair of undamaged trams demonstrating that the method can be successfully replicated for different vehicles.
4
Content available 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
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2022
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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.
5
Content available 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
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2021
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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.
6
Content available Time-frequency methods for processing non-stationary diagnostic vibroacoustic signals
Mokrzan Daniel, Szymański Grzegorz M.
Pojazdy Szynowe
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2021
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Nr 3
44--57
EN
The article presents the issues of interpretation of non-stationary vibroacoustic diagnostic signals. The reasons of the incomplete usefulness of the traditional analysis solely in the field of time or frequency for such cases are explained. The use of time-frequency methods is presented as the proposed solution. The literature was reviewed in aspect of the methods currently used or on which the research is carried out. Older applications, such as the short-time Fourier transform and more complex and contemporary applications such as the Hilbert-Huang transform, are mentioned. Further development directions were also assessed, taking into account the combination of methods and the use of artificial neural networks, assessing the latter as giving the greatest potential in aspect of the evolution of signal processing methods.
PL
W artykule zaprezentowano problematykę interpretacji niestacjonarnych wibroakustycznych sygnałów diagnostycznych. Wyjaśniono przyczyny niepełnej przydatności tradycyjnej analizy wyłącznie w dziedzinie czasu lub częstotliwości dla takich przypadków. Jako proponowane rozwiązanie przedstawiono wykorzystanie metod czasowo-częstotliwościowych. Dokonano przeglądu literatury w aspekcie metod obecnie wykorzystywanych lub nad którymi prowadzone są badania. Wymieniono zarówno zastosowania starsze jak krótkoczasowa transformata Fouriera oraz bardziej złożone i współczesne jak transformata Hilberta-Huanga. Dokonano również oceny dalszych kierunków rozwoju z uwzględnieniem kombinacji metod oraz wykorzystania sztucznych sieci neuronowych oceniając te ostatnie jako dające największy potencjał w aspekcie ewolucji metod przetwarzania sygnałów.
7
Content available Methods for reducing the number of collisions between wild animals and rail vehicles
Milewicz Julia, Mokrzan Daniel, Szymański Grzegorz M.
Pojazdy Szynowe
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2021
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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.
8
Content available 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
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2021
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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.
9
Content available 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
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2021
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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.
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