Modelling of acoustic emission generated due to pitting on spur gear

Acoustic emission (AE) is a non-destructive technique which is used for condition monitoring and health diagnosis of rotating machine elements such as gearboxes. Several experimental investigations have been performed which shows the capability of AE technique to fault or defect detection on gears. It has been also investigated by experimental studies that if the size of defect increases, the AE level also increases. But to the best knowledge of authors, there is lack of mathematical model to understand the physics behind the same. This study presents a theoretical model to establish a relationship between size of fault/defect and energy of AE generated during gear meshing on the bases of interaction of asperity and protrusion around the defect using Hertzian contact approach, varying sliding velocity of gear tooth mechanism, and statistical concepts with the aid of surface topography of gear tooth having the pit of different size. The model is developed by considering the influence of three phenomena during gear mesh cycle: load sharing, lubrication and dynamic load condition. The developed theoretical model is validated with experimental study performed on IAE gear lubrication testing machine and satisfactory results have been observed.