A. Wilk

Vibration Processing Techniques for Fault Detection in Gearboxes

Vibration analysis is a very important tool in condition monitoring of operating machines. Many signal processing methods have been developed to extract information about incipient faults from externally measured vibration signals. The article presents the laboratory examinations of some faults in spur and helical gears. In case of spur gears two types of progressing local faults of cracked and chipped gear tooth were simulated and the smoothed pseudo Wigner-Ville distribution was used to demonstrate fault advancement via residual vibration signal analysis. Observing changes in the features of the WV distribution in the contour plots and changes of Kurtosis value monitored the progression of a fault. In case of helical gears some signal changes of transverse vibration velocity of shafts during the process of pitting growth in the tooth working surface have been investigated. Some new indices of pitting wear have been suggested and compared with other non-dimensional discriminants.Copyright

Application of a Continuous Wavelet Transform for the Diagnosing of Excessive Valve Clearance of the Combustion Engine

Combustion engines are the components of means of transport which during service are exposed to the occurrence of excessive clearances. The diagnosing of the condition of the engine requires developing methods which could be useful during both continuous and single checks of the engine. Application of measurements and acoustic signal processing may facilitate a quick diagnosis of the engine without any additional disassembly work. As part of the study, research was conducted to develop a non-invasive method of diagnosing excessive clearance of the combustion engine. Based on the recorded acoustic signals of the combustion engine and reference signals of the momentary crankshaft position, a method was developed to diagnose an increased valve clearance in the combustion engine. In this method, processing of the recorded acoustic signals by means of the continuous wavelet transform was applied together with a comparison of their instantaneous energy, depending on the crankshaft rotation angle and timing angles, as well as the scale parameters of time and frequency distributions.