Papers by Author: Aleš Belšak

Abstract: A crack in the tooth root is probably the least desirable problem in gear unit operation; it often leads to failure. Signals produced by a gear with a crack in the tooth root, produced through real operating conditions, and signals caused by a faultless gear are used for the analysis. By monitoring vibrations it is possible to detect the presence of a crack. A fatigue crack in the tooth root brings about significant changes in tooth stiffness. Other faults are usually linked with modifications of other dynamic parameters. Time Frequency Analysis tools, e.g. Wavelets Analyses, are used to analyse a non-stationary signal. The wavelet transform is chosen for the analysis. The wavelet function similar to the dynamic reaction of the crack in the tooth root is selected. By means of the methods and the analysis presented in this paper, the reliability of determining modifications in signal vibrations is improved.

Abstract: A crack in the tooth root, which often leads to failure in gear unit operation, is the most undesirable damage caused to gear units. This article deals with fault analyses of gear units with real damages. Numerical simulations of real operating conditions have been used in relation to the formation of those damages. A laboratory test plant has been used and a possible damage can be identified by monitoring vibrations. The influences of defects of a single-stage gear unit upon the vibrations they produce are presented. Signal analysis has been performed also in concern to a non-stationary signal, using the Time Frequency Analysis tools. Typical spectrograms, which are the result of reactions to damages, are a very reliable indication of the presence of damages.

Abstract: This paper presents a control and diagnostics model of single stage gear wheels using acoustic responses. The model is based on various methods and procedures that provide information about the generator’s condition and, specifically, its service life. Four procedures are combined in this model: the mathematical module of the gear wheel that translates the complete mechanical module into mathematical form, the adaptive FIR (Finite Impulse Response) filter that calculates impulse responses from the non-linear system, the module for calculating any impulse response, and the FFT (Fast Fourier Transform) frequency analysis used for simulating frequency spectrums. The result of the simulation is the sound frequency spectrum that allows the analysis of gear wheel tooth damage and, based on this spectrum, calculation of the remaining service life and/or the maintenance process.