2020 №01 (01) DOI of Article
2020 №01 (03)

Technical Diagnostics and Non-Destructive Testing 2020 #01
Technical Diagnostics and Non-Destructive Testing #1, 2020, pp. 17-27

Application of a specialized nondestructive testing device for analysis of vibration signals of bearing assmeblies by the methods of mutual nonstationary analysis

R.M. Yuzefovych2, I.M. Javorskyj3, O.Y. Dzeryn1, G.R. Trokhym1, I.H. Stetsko1, I.Y. Matsko1

1G.V. Karpenko Physico-Mechanical Institute of the NAS of Ukraine. 5 Naukova Str., 79060, Lviv, Ukraine . E-mail: roman.yuzefovych@gmail.com
2National University «Lvivska Politekhnika». 12 S.Banderi Str., 79013, Lviv, Ukraine
3Technological-Natural University. 7 Al. prof. S. Kaliskiego, 85796, Bydgoszcz, Poland

Vibration signals from complex mechanical systems, which are under the impact of dynamic loading, are formed by responses from many assemblies. When studying such signals, the question arises of analysis of the impact of possible defects on their structure, which initiate in each of the elements of the ball bearing assembly. Defect initiation in mechanical system elements results in nonlinear effects in the properties of vibrations. Such effects lead both to appearance of new harmonics in the deterministic component of vibration, and to interaction of this component with stochastic oscillations, which are due to fluctuations of the thickness and viscosity of lubrication, changes of friction forces, spontaneous and uncontrollable changes of working loads, etc. The above interaction leads to violation of the strict periodicity of deterministic oscillations, they are modulated by phase and amplitude. The noted features of vibrations can be adequately described by a mathematical model in the form of mutual periodically correlated random processes. The work presents the integral function of coherence, which quantitatively characterizes the stochastic inter-relation between the properties of non-stationarity of two periodically correlated random signals that is manifested in the periodical change in time of their mutual spectral characteristics, as well as component function of coherence, which is determined by mutual spectral densities of individual modulating processes. Technical characteristics of the developed specialized nondestructive testing device «Compact-Vibro» are given. Results are considered, which were obtained using this device during performance of vibration examinations of industrial facilities of Ukraine. 6 Ref., 32 Fig.
Keywords: periodically correlated random processes, coherence function, nondestructive testing device, vibration signal, diagnostics

Received: 02.12.2019
Published: 02.02.2020


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