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1

Detection of the presence of rail corrugation using convolutional neural network

Tabaszewski Maciej, Firlik Bartosz

Engineering Transactions

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2022

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Vol. 70, iss. 4

339--353

EN

Rail corrugation is a significant problem not only in heavy-haul freight but also in light rail systems. Over the last years, considerable progress has been made in understanding, measuring and treating corrugation problems also considered a matter of safety. In the presented research, convolutional neural networks (CNNs) are used to identify the occurrence of rail corrugation in light rail systems. The paper shows that by simultaneously measuring the vibration and the sound pressure, it is possible to identify the rail corrugation with a very small error.

2

Ultrawide bandgap by 3D monolithic mechanical metastructure for vibration and noise control

Muhammad, Lim C. W.

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 2

197--207

EN

The all-direction vibration and noise control by metastructures have received high demands in the vibroacoustic community in the recent past to solve multiple vibration and noise-related engineering problems. This class of elastic metamaterial has grasped a strong root in this community due to its versatile wave manipulation characteristics, including frequency bandgap property. Inspired by the idea of metamaterial and computational mechanics in breakthrough research for vibration and noise control technology, the present study proposes a novel 3D phononic metastructure that is capable of generating low-frequency extremely wide three-dimensional complete bandgap with relative bandwidth Δω/ωc=171.5%. The study is based on analytical modeling, numerical finite element analysis and experiment on 3D printed prototype. The proposed monolithic metastructure is comprised of elastic beams connected orthogonally with rigid spherical masses. The axial compression mode of a complete unit cell structure and the flexural stiffness of beams are manipulated to generate low-frequency extremely wide bandgap. By the principle of modal masses participation/mode separation, the opening and closing of the bandgap is analyzed. The results are corroborated by two different numerical FE solutions on the frequency response spectrum, and the models are validated by performing a vibration test on 3D printed prototype. The wave attenuation over ultrawide frequency range is demonstrated through numerical and experimental approaches, and excellent agreement is reported. The proposed monolithic metastructure design may find potential applications in industrial and infrastructural devices where noise and vibration control over ultrawide frequency range are desirable in all directions.

3

Problemy eksploatacji silników indukcyjnych z asymetrią elektromagnetyczną – wybrane przypadki

Petryna J., Sułowicz M., Guziec K.

Maszyny Elektryczne : zeszyty problemowe

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2016

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Nr 1 (109)

161--168

PL

W pracy przeanalizowano kilka przypadków negatywnych zjawisk towarzyszących eksploatacji silników indukcyjnych z asymetrią elektromagnetyczną. Zjawiska te, rozmaitego pochodzenia, nieraz nakładają się na siebie, utrudniając diagnozę. Rozpatrzono pracę silnika niskoobrotowego dużej mocy, emitującego specyficzny hałas, którego intensywność wzrastała w miarę zwiększania obciążenia. Aby wyjaśnić przyczyny zjawiska, oprócz pomiaru prądu w stanach dynamicznym i stanie ustalonym zastosowano pomiar strumienia unipolarnego oraz drgań mechanicznych, ponieważ sam pomiar prądu nie dawał całkowicie jednoznacznej odpowiedzi co do przyczyn problemu. Wyniki badań wskazały na defekt klatki z możliwym jednoczesnym zwarciem blach pakietu wirnika. Z kolei na stacji prób poddano badaniom 2 jednakowe silniki 6kV, których praca sugerowała także symptomy wewnętrznej asymetrii elektromagnetycznej poprzez specyficzny dźwięk. Tu podobnie dokonano pomiarów prądu, strumienia i drgań. W przypadku jednego z silników analiza odfiltrowanego prądu rozruchowego w postaci charakterystycznych modulacji wskazała na początkową degradację klatki i/lub ewentualne zwarcie części blach pakietu wirnika, na co wskazywałyby efekty akustyczne. W drugim przypadku kształt odfiltrowanego prądu rozruchowego diametralnie odbiegał od znanego wzorca, typowego dla defektu klatki. Specyficzne zmiany sygnału diagnostycznego mogą wskazywać na poważniejszy problem w wirniku, np. całkowitą degradację pakietu spowodowaną zwarciami o szerokim zasięgu.

EN

The study analyzed several cases of adverse events associated with the operation of induction motors with electromagnetic asymmetry. These phenomena, of various origin, often overlap, making it difficult to diagnose. A high power low speed motor, emitting a specific noise which intensity increased with increasing load, was considered. To explain the reasons for the phenomenon, in addition to the current measurement in the dynamic and steady states, a unipolar flux and mechanical vibrations measurements were applied because the current measurement did not give a completely clear answer as to the cause of the problem. The test results indicated a defect in the rotor cage with a possible simultaneous short circuit insi de the rotor sheet package. In turn, at the testing station two identical 6 kV motors which operation suggested symptoms of internal electromagnetic asymmetry by a specific sound, were subjected to the tests. Similarly, the measurements of current, flux, noise and vibration were carried out. In case of one of the motors the analysis of the filtered start-up current in the form of characteristic modulation pointed to the initial degradation of the cage and/or some short circuit of a portion of the rotor sheet package, what would the soundeffects indicate. In the second case, the shape of the filtered start-up current radically differed from the known standard pattern, typical for the cage defect. The specific changes to the diagnostic signal may indicato a serious problem in the rotor, for example a total degradation of the package due to a wide range short circuits inside.