Methods for detecting fatigue cracks in gears

A crack in the tooth root is the least desirable damage caused to gear units and it often causes failure of gear unit operation. For fault analyses presented in this article, gear units with real damages or faults produced on the basis of numerical simulations of real operating conditions are usedtests were carried out in a laboratory test plant. Damages in gear units can be identified by monitoring vibrations. The influences of a crack in a single-stage gear unit on produced vibrations are presented. Significant changes in tooth stiffness are caused by a fatigue crack in the tooth root whereas, in relation to other faults, changes of other dynamic parameters are more expressed. Non-stationary signals are analysed, using the family of Time Frequency Analysis tools, which include Wavelets and Joint Time Frequency Analyses

Method for detecting fatigue crack in gears

The most undesirable damage that can occur in gear units is crack in the tooth root as it often makes gear unit operation impossible. Monitoring vibrations can be used to detect defects. Time signals are acquired experimentally and afterwards. Different methods can be used to analyse them. The changes in tooth stiffness caused by a fatigue crack in the tooth root are of significance. The dynamic response of a gear unit with a damaged tooth differs from the one of an undamaged tooth. Amplitudes of time signal are, by time-frequency analysis, presented as a function of frequencies in spectrum

Crack identification in gear tooth root using adaptive analysis

Problems concerning gear unit operation can result from various typical damages and faults. 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. A laboratory test plant has been prepared. It has been possible to identify certain damages by monitoring vibrations. In concern to a fatigue crack in the tooth root significant changes in tooth stiffness are more expressed. When other faults are present, other dynamic parameters prevail. Signal analysis has been performed also in concern to a non-stationary signal, using the adaptive transformation to signal analysis

Adaptive wavelet transform method to identify cracks in gears

Many damages and faults can cause problems in gear unit operation. A crack in the tooth root is probably the least desirable among them. It often leads to failure of gear unit operation. By monitoring vibrations, it is possible to determine the presence of a crack. Signals are, however, very noisy. This makes it difficult to define properties of individual components. Wavelet analysis is an effective tool for analysing signals and for defining properties. In this paper, a denoising method based on wavelet analysis, which takes prior information about impulse probability density into consideration, is used to identify transient information from vibration signals of a gear unit with a fatigue crack in the tooth root

Plant protection product dose rate estimation in apple orcahrds using a fuzzy logic system

In the process of applying a plant protection product mixed with water (spray mixture) at the prescribed concentration with conventional sprayers for chemical protection of tree canopies in an orchard, standard models are used to express the dose rate of the plant protection product. Characteristic properties of the tree canopy in an orchard are not taken into consideration. Such models result in fixed quantities of spray mixture being sprayed through individual nozzles into a tree canopy. In this research work, an autonomous system is presented, which ensures a controlled quantity of spray mixture sprayed through the nozzles onto different tree canopy segments. The autonomous system is based on a fuzzy logic system (FLS) that includes information about the estimated leaf area to ensure more appropriate control of the spray mixture. An integral part of the FLS is a fuzzy logic controller for three electromagnetic valves operating in the pulse width mode and installed on the axial sprayer prototype. The results showed that, with the FLS, it was possible to control the quantity of spray mixture in the specific range depending on the estimated value of the leaf area, with a quantitative spray mixture average saving of 17.92%. For the phenological growth stage BBCH 91, this method represents a powerful tool for reducing the quantity of spray mixture for plant protection in the future

Analysis of noise sources produced by faulty small gear units

Noise source vizualization represents an important tool in the field of technical acoustics. There are many different techniques of noise source visualization. Most of them, however, are intended for a specific noise source in a specific type of acoustic environment. Consequently, a certain visualization method can be used only for certain types of noise sources in a specific acoustic environment and in a restricted frequency area. This paper presents a new visualization method of complex noise sources on the basis of the use of an acoustic camera. A new algorithm has been used, which makes it possible to visualize all types of different complex noise sources. Monopole, dipole or quadropole noise sources can be observed simultaneously. It is possible to track a moving noise source by means of an acoustic camera. In addition to that it is possible to observe various transient acoustical phenomena. Through the use in diagnostics, it is possible to define, by means of noise, the condition of mechanical systems at an advance level