Wyniki wyszukiwania - BazTech

1

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.

2

Vibration analysis of Kenyir Dam power station structure using a real scale 3D model

Arbain Azizi, Ahmad Mazlan Ahmad Zhafran, Zawawi Mohd Hafiz, Mohd Radzi Mohd Rashid

Civil and Environmental Engineering Reports

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2019

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Vol. 29, no. 3

48--59

EN

In this paper, the vibration analysis in terms of modal and harmonic responses are investigated for the power station structure of Kenyir Dam in Terengganu, Malaysia. Modal analysis is carried out to provide the dynamic characteristics of the power station which includes the natural frequencies and mode shapes. Meanwhile, the harmonic response analysis is performed by applying the force to the structure to obtain the Frequency Response Function (FRF) in certain range of frequencies. A real scale threedimensional (3D) model of the Kenyir Dam power station is constructed using Solid Works software and imported to ANSYS software for the Finite Element (FE) analysis. A proper boundary condition is taken into consideration to demonstrate the real behaviour of the power station structure. From the results, six most significant natural frequencies and mode shapes including the FRF in all three axes are selected. The highest natural frequency value occurred at 5.4 Hz with the maximum deflection of 0.90361 m in the z axis direction. This value is important in order to verify whether the structure can overcome the resonance phenomenon from the external disturbance forces in the future.

3

Analysis of High Frequency Vibration of Tram Resilient Wheel

Melnik R., Sowinski B.

Machine Dynamics Research

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2018

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Vol. 42, No. 3

67--79

4

Wykrywanie uszkodzeń węzłów w modelu ramy stalowej na podstawie analizy inertancji

Ziaja D., Miller B.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2017

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z. 64, nr 2/I

247--255

PL

W artykule przedstawiono możliwość detekcji uszkodzeń węzłów na podstawie analizy proporcji pomiędzy wytypowanymi fragmentami funkcji przejścia (FRF). W ramach zadania wykonano eksperyment na modelu laboratoryjnym dwukondygnacyjnej ramy portalowej, którą poddano testom dynamicznym i dla której określono model modalny. Funkcję przejścia odpowiadającą wybranym punktom układu potraktowano jako sygnał w dziedzinie częstotliwości. Wyznaczono odcięte środków ciężkości kwadratów sygnału wybranych fragmentów funkcji, które następnie potraktowano jako dane wejściowe w metodzie wektorów nośnych. Zaproponowane podejście umożliwia skuteczną detekcję uszkodzeń węzłów badanego modelu.

EN

The article presents the possibility of nodes failures detecting based on the analysis of the proportions between the selected intervals of FRF function. Within the scope of the task an experiment was performed on the laboratory model of a two-storey portal frame, which was subjected to dynamic tests and for which a modal model was defined. FRF function for selected system points was treated as a signal in the frequency domain. For the relevant fragments, the centers of gravity of the signal squares were determined, which were then used as input data in the Support Vector Machines (SVM) method. The proposed approach enables effective detection of connection damage in the tested structure.

5

Test setup for examination of magneto-mechanical properties of magnetorheological elastomers with use of a novel approach

Bocian M., Kaleta J., Lewandowski D., Przybylski M.

Archives of Civil and Mechanical Engineering

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2016

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Vol. 16, no. 3

294--303

EN

This paper presents an experimental setup aiming at evaluating the magneto-mechanical and damping properties of the thermoplastic magnetorheological elastomer (MRE). The idea of the system is to create controllable conditions similar to those present in a vehicles and other mechanical constructions and to make it possible to determine parameters only relating to the MRE material itself. The test stand is based on four samples stimulated with highly effective Halbach arrays. The upper plate of the test stand is excited with use of a modal shaker to assure a constant impact force value during each test. This enables control of impact character and allows automation of the test stand. The last section of this paper presents preliminary test conducted to find the resonance frequency dependence on the impact force of the system for a constant value of magnetic field. The results indicate non-linear behavior of the material and therefore exclude use of the simple Kelvin-Voight model based approach for damping properties determination, that is a commonly used model for description of different materials.

6

Konsolidacja czół uzwojenia, metoda wydłużenia okresu eksploatacyjnego generatorów

Dusza T., Bojara S., Rudolf P.

Przegląd Elektrotechniczny

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2014

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R. 90, nr 1

239--241

PL

W artykule przedstawiono wyniki prac konsolidacyjnych przeprowadzonych dla generatorów średniej mocy. Prace polegają na wyznaczeniu parametrów charakteryzujących stan techniczny czół uzwojenia stojana generatora oraz zastosowaniu specjalnie zaprojektowanego systemu dosztywniającego czoła uzwojenia generatora. Zastosowanie odpowiedniego systemu dosztywnień zmniejsza amplitudy drgań czół w wyniku czego zmniejsza się intensywność procesów zmęczeniowych izolacji głównej prętów w strefie czół uzwojenia. Parametry opisujące stan techniczny czół uzwojenia stojana generatora wyznaczane są na podstawie eksperymentalnej analizy modalnej oraz analizy FRF.

EN

The article presents the results achieved after consolidation works conducted in behalf of medium seized generators. The works consisted in determining the parameters characterizing the technical conditions of the stator winding heads as well as applying a specially designed generator winding heads stiffening system. The application of an appropriate stiffening system diminishes the amplitude of heads vibrations resulting in a decrease of fatigue processes intensity on the bar main insulations in the area of the winding heads. The parameters describing the technical conditions of the stator winding front ends are determined on the basis of an experimental modal analysis and FRF analysis.

7

Wykorzystanie sterowania samolotem w ruchu programowym w procesie syntezy funkcji FRF

Krawczyk M., Graffstein J.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2007

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z. 71 [238]

135-144

PL

W pracy przedstawiono ogólne założenia programu SOFIA podejmującego próbą rozwiązania problemu bezpiecznego, w pełni automatycznego sprowadzenia samolotu na ziemią, w przypadku wystąpienia działań terrorystycznych. Kolejno omówiono strukturę opracowywanego systemu FRF (Flight Reconfiguration Function) realizującego to zadanie oraz kwestię sterowania lotem w przestrzeni wymagającej realizacji złożonych manewrów pilotażowych. W szczególności pokazano metodę syntezy programu lotu po wygenerowanej przez system FRF trajektorii rozpiętej w przestrzeni 4D, której działanie zilustrowano wynikami symulacji numerycznej.

EN

The paper presents general assumption of SOFIA FP6 program, be part of the challenge of developing concepts and techniques enabling the safe and automatic return to ground in the event of hostile actions. Successively the structure of FRF (Flight Reconfiguration Function) as well as the problem of complex maneuvers control were discussed. Particularly the synthesis method for projection of 4D trajectory was discussed as well as simulation results of aircraft prescribed trajectory flight were demonstrated.