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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.

2

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.

3

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.

4

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.