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1
Content available Monitoring of the crack propagation in welded joint of the tank using multi-class recognition
Bouraou N., Rupich S., Lukianchenko O., Kostina O.
Vibrations in Physical Systems
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2018
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Vol. 29
art. no. 2018013
EN
The numerical analysis of the vertical weld-fabricated steel tank is carried out taking into account the defects of the welds in the form of through-the-thickness cracks of different lengths and numbers, which are located in different zones of the object's ring. The influence of defects on the stress of the tank is estimated in the places of sensors installation under the action of vertical load. The usage of multi-class recognition is proposed by classifier based on Probabilistic Neural Network for monitoring of the crack propagation. Multidimensional vectors of diagnostic features are used for multi-class recognition. The training set of vectors is formed for defect-free and defect conditions, the classifier is trained and tested, the analysis of recognition efficiency is carried out by using the probability of correct multi-class recognition.
2
Content available Vibration condition monitoring of the vertical steel tanks
Bouraou N., Lukianchenko O., Tsybulnik S., Shevchuk D.
Vibrations in Physical Systems
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2016
|
Vol. 27
55--60
EN
This paper presents the results of numerical analysis and physical simulation of the vertical steel tank for usage in the vibration condition monitoring system. For purposes of the numerical analysis the tank is considered as the double steel cylinder consisting of the inner and outside shells. The discrete model of a tank is developed. The estimations of stress and deformation are obtained when the following vertical loads are exerting: weight of the fuel, weight of the tank roof and other structural elements or equipment. The physical model of a tank is used for physical simulation. The impulse responses of this model are measured and analyzed for different levels of tank filling. The methods of Prony and Steiglitz-McBride are used for estimation of the vibration damping factor which depends on the level of tank filling.
3
Content available Improvement of the vibration diagnostics of rotation shaft damage based on fractal analysis
Bouraou N., Pavlovskyi O., Pazdrii O.
Vibrations in Physical Systems
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2016
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Vol. 27
61--66
EN
This work is devoted to further research and improvement of the vibration diagnostics of the initial crack-like damage of rotation shaft in aviation gas-turbine engines (GTE). We propose to use fractal analysis of the accelerating shaft response in order to increase the damage detection efficiency. Responses of the accelerating shaft are derived by using simulation in absence and in presence of the initial traverse crack. The responses of the cracked shaft have sub-critical peaks; the increase in size of a crack leads to the increase in peak values of the vibration amplitude in the range of sub-harmonic resonances. The Hurst exponent is obtained for the time series in the range of sub-harmonic resonances. The research shows that a small change in the crack size results in considerable change of the Hurst exponent, which allows to detect the mentioned sub-harmonic resonances of the measured signal in order to identify the initial crack-like damage of the rotation shaft.
4
Content available On-board vibration diagnostics of shaft damage of the aviation engine
Pavolvskyi O., Bouraou N.
Vibrations in Physical Systems
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2014
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Vol. 26
229--234
EN
This work is devoted to the further researches and development a new on-board multilevel vibration control system of aviation gas-turbine engines (GTE). We propose to introduce new diagnosis level (subsystem) into development multilevel vibration control system for detection of the initial crack-like damage of rotor shaft. The proposed subsystem works at the non-steady-state modes of GTE, for example during startup at the acceleration to operating speed. The basis of this approach is the fact of the occurrence of sub harmonic resonances of accelerating cracked shaft response. It is necessary to extract the main rotor harmonic vibration at the nonsteady-state mode for crack diagnosis in practice. The narrow-band digital tracking filter is carried out for this aim, the central frequency of pass band is changing according the rotor rotation frequency. The efficiency of the proposed subsystem is demonstrated by the results of computer simulation.
5
Content available remote The evaluation of the crack-like damage parameter of blades at the vibroacoustical diagnosis of the gas-turbine engines
Bouraou N., Ignatovich S.
Vibrations in Physical Systems
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2012
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Vol. 25
83--88
EN
This work is devoted to vibroacoustical condition monitoring of the gas-turbine engines (GTE) blades and diagnosis of the crack-like damages at the steady-state and non-steady-state modes of GTE. For detection of the mentioned damages we proposed the application and further development of the low-frequency vibroacoustical diagnostic methods which use vibrating and acoustical noise as diagnostic information. The following amplitude dimensionless characteristics are used as fault features: probability factor, peak factor and factor of background. The evaluation of the crack-like damage of the blades is carried out at the steady-state and nonsteady-state modes by using the generalized likelihood method. The statistical quality of the received estimations is investigated.
6
Content available remote Multilevel vibration control system of aviation gas-turbine engines
Pavlovskiy O., Bouraou N., Iatsko L.
Vibrations in Physical Systems
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2012
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Vol. 25
323--328
EN
This work is devoted to the development a new multilevel vibration control system of aviation gas-turbine engines (GTE). The bases of the new system are: existing aboard vibration control system for current control and awareness about actual levels of vibration at the harmonics of the rotor rotation (main level); complementary dedicated microcontroller for analysis of “normal vibration” in order to predict or detect small damages of engine systems and details (auxiliary level); signal processing methods for damages diagnosis and decision making about GTE condition. The efficiency of the proposed system and using the signal processing methods is demonstrated by the results of computer simulation of the processes of receiving the information about the GTE vibrating condition, transformation and analysis of it at the main and auxiliary levels.
7
Content available remote Vibroacoustical diagnosis of the crack-like damages of aircraft engine blades at the steady-state and non-steady-state modes
Bouraou N., Sopilka I.
Vibrations in Physical Systems
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2010
|
Vol. 24
69--74
EN
The work is devoted to condition monitoring and vibroacoustical diagnosis of the crack-like damages of the gas-turbine engines (GTE) blades at the steady-state and non-steady-state modes of GTE. The developed diagnostic model of GTE is presented and the influence of damage on the measured vibro- and acoustical signals at the steady-state and non-steady-state modes of GTE is determined. The application of the following signal processing methods: Polyspectral (Higher-Order Spectral) analysis, Wavelet-transformation and dimensionless characteristics of the vibroacoustical signals is proved. The efficiency of signal processing methods is demonstrated by the results of numerical simulations of the turbine stage at the steady-state and non-steady-state modes of vibration excitation. The fault features are detected and investigated.
8
Content available remote Theoretical bases of vibration diagnostics of anchor against landslide constructions
Bouraou N., Klofa I., Zsukovskij Y., Kulish E.
Vibrations in Physical Systems
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2010
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Vol. 24
63--68
EN
The given work is devoted to development of theoretical bases of a new vibrating diagnostics method and evaluation a current condition of the anchor. The research of the pulse response of the anchor against landslide construction is a basis of vibrating diagnostics of a tension condition an anchor, detection of feature of abatement of a tightness, and definition of character of its dependence on a changing stretching force. The elastic body with the distributed parameters (a string) is used as the diagnostic model of the tense and fixed core of an anchor. Dependences of own frequencies changing of the pulse response of an anchor on a tightness changing at deformations and displacement of a place of fastening of an anchor are defined. The discrete model of an anchor against landslide construction is developed and researched for definition of dependences between parameters of an anchor condition and vibrating characteristics of a retaining wall, which is accessible to carrying out of measurements.
9
Content available Decision making about aircraft engine blades condition by using neural network at the steady-state and non-steady-state modes
Bouraou N., Zazhitskiy O.
Diagnostyka
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2008
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nr 3(47)
71-74
EN
The work is devoted to problem solution of the gas-turbine engines (GTE) blades condition monitoring and diagnosis of the crack-like damages at the steady-state and non-steady-state modes of GTE. It is based on the development of theoretical basis of the vibroacoustical diagnosis methods, the application of the modern signal processing methods and new information technique for decision making. The application of the following signal processing methods: Wavelet-transformation and dimensionless characteristics of the vibroacoustical signals is proved. Neural networks are used for decision making about blades condition by the above mentioned features application. Classification of turbine blade condition was carried out using a two-layer Probability Neural Network (PNN).
10
Content available remote Simulation of the vibratory processes for the problems of monitoring and diagnosis of gas-turbine engines rotary details
Bouraou N., Marchuk P., Yatcenko A.
Vibrations in Physical Systems
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2002
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Vol. 20
110--111
11
Content available remote Diagnostyka wibroakustyczna i metoda oceny uszkodzeń wirujących elementów maszyn turbinowych
Bouraou N., Marchuk P., Tyapchenko A.
Vibrations in Physical Systems
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2000
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Vol. 19
66--67
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