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Contents of the issue
1G.V. Karpenko Physico-Mechanical Institute of the NAS of Ukraine. 5 Naukova Str., 79060, Lviv, Ukraine .
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,
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