Jacek Dziurdź

Application of Correlation and Coherence Functions in Diagnostic Systems

Main problem in operation of diagnostic systems of power transmission systems is analysis of the energy of these harmonic components of the signal, which could be considered as diagnostic symptoms. Measured values can be affected i.a. by energy of random effects or other, less important components of the signal. Coherence and correlation functions are ones of classical methods of signal analysis being applied to analyze deterministic signals affected by random noise. In time domain autocorrelation function allows to determine time cohesion between adjacent fragments of analyzed process, shifted by different time values. In the paper author describes the method of minimization the impact of disturbances on signals being analyzed using basic properties of autocorrelation function. For the analysis of deterministic phenomena (including nonlinear) ordinary coherence function was applied. Showed examples were implemented and solved in MATLAB environment. The method was verified by analysis of model signals and signals (vibration accelerations) recorded on real object.

Modelling of the Toothed Gear Operations with the Application of the Analysis of the Gear Sliding Mesh Velocity Changes

Searching for effective diagnostic methods of basic elements of driving systems is still the actual problem. The most often the vibroacoustic diagnostics based on the analysis of vibrations and noises generated by the working system is applied. Driving systems of vehicles are rather complicated. They consist, among others, of various types of toothed gears. Within the vibroacoustic signals recorded during their operation not only harmonic components – being the effect of these gears operations - are present, but also components generated by other elements. Due to this, there is a necessity of the development of models of the vibroacoustic signals generation by the main elements of the driving system. Such models will allow to identify – within the recorded signals – the harmonic components related to processes occurring during the gear operation. These models should be relatively simple due to the possibility of their application in diagnostic devices operating in the ‘on line’ mode. Modelling of the single-stage toothed gear, with the application of the analysis of the gear sliding mesh velocity changes, is presented in the hereby paper.

Proposition of the vibroacoustic diagnostic methodology of testing toothed gears of marine drives

ABSTRACT The proposal of the Authors of the hereby paper is based on measuring vibrations of the gearbox housing and on the application of the generalised coherence analysis. The diagnostic model proposed by Klekot [1992. Simplified kinematic model of a spur gear with involute teeth elaborated for analysis of gear vibroactivity. Mach Vib. 4(1):261–267] was accepted as the standard, which is relatively simple, but takes into account the influence of the mesh geometry evolution during its operations on this mesh dynamics. In order to identify the proposed model, the authors performed the active diagnostic and model experiments for the toothed wheels pair. As a result, you can see how selective and practically insensitive to the interferences the measure of the evolution of gear tooth damage can be.

Analysis of Action Viscous Torsional Vibration Damper of the Crankshaft Based on Transverse Vibration the Engine Block

The article presents an example of research results of the mechanical vibrations of the internal combustion engine with a viscous torsional vibration damper of the crankshaft for different values of the viscosity of silicone oil. A comparison of the crankshaft torsional vibration and the transverse vibration motor body was made. There was proposed the use of the information contained in the transverse vibration signals in order to determine the changes in the technical condition of the viscous damper (changes in viscosity of silicone oil fillingthe damper). Accepting the argument which assumes that there exists the coupling vibration and torsional shaft bent in transverse vibration signals, there should appear symptoms associated with changes in the torsional vibrations. In order to prove this thesis there was conducted active research experiment. Measurements of transients during engine acceleration were made. There was presented the example of the results of measurements of the crankshaft torsional vibrationand the transverse vibration of the motor body.