Objectives
The objective of this experiment is to detect fault in a gear by using vibration signature analysis.
Introduction
Gears are universally used in today’s high speed rotating machinery. They have been applied from the household appliances, such as vacuum cleaners and lawn mowers etc. to sophisticated systems such as aircraft and automobile drive trains. Due to greater expectations in higher operating speeds and larger applied load premature failures in gears due to excessive wear increase substantially, and sometimes, even result in catastrophic injuries, and substantial financial losses. Thus, the detection of fault in gears could be a valuable diagnostics and prognostics tool for today’s machinery.
Presently, the advancements in research were aimed at finding a reliable monitoring strategy for gear transmission systems. For the last two decades, a variety of fault detection procedures have been developed. One of the most promising procedures for detecting faults in gears is the vibration signature analysis. Vibration signature analysis does not require shutdown of the rotating machinery, and can be carried out online by a computer-based machine health monitoring system. The acquired vibration signals are processed by a variety of methods to identify the faults of gears. However, some times, measurement of vibration in the gearbox is not easy because of the inaccessibility in mounting the vibration transducers. In complex machineries the vibration signal due to gear may be mixed up with the noise and vibrations due to other components. So interpretation of the vibration signals, in some cases, may require extensive experiences and knowledge in vibration
signal interpretations for an accurate identification of the faults and their corresponding locations.
Vibration signature analysis is very popular technique for fault detection in gears. Various time and frequency domain approaches has been applied to analyze the vibration signals. The time domain methods analyze the amplitude and phase information of the vibration time signal to detect the fault of gear-rotor-bearing system.Some are using the difference of vibration amplitude and phase due to the damage of components to detect faults at gears and bearings.
Sources of gear vibration
1) A periodic signal at the tooth meshing rate due to deviations fron the ideal tooth profile.
2) Amplitude modulation effects due to variations in tooth loading.
3) Frequency modulation effects due to rotational speed fluctuations and/or non uniform tooth spacing.
4) Additive impulse which are generally associated with local tooth faults.
