Gear transmission systems are widely used in many industry applications. Increased demand for higher-speed, improved performance and longer-lived machinery, makes the prediction and control of gear vibration and noise, as well as the early detection and diagnosis of gear defects important considerations. Many researchers use dynamic modelling of gear vibration to increase knowledge about the vibration generating mechanisms in gear transmission systems and the dynamic behaviour of gear transmission systems in the presence of some kinds of localized tooth defects.
This project aims to advance the current understanding of gear dynamics by introducing more accurate and realistic gear dynamic modelling strategies for cylindrical gear (spur gear and helical gear) transmission systems with and without localized tooth defects (tooth fillet crack and spalling defect). A series of studies have been conducted to reflect different aspects of gear dynamics. The main conclusions can be as summarized below:
- Corner contact effect should not be neglected in the gear dynamic analysis if no or an insufficient amount of tooth profile modification is applied when the gears are working under heavy load.
- The dynamic coupling behaviour is obvious in the direction of off-line of action when a gear pair with gear eccentricities is running at relatively low-speed range where the resonances of gear torsional vibration are most likely to be excited.
- The addendum modification can affect gear dynamics through the back-side mesh stiffness, especially when the gears are working under light load or idling conditions.
- Special attention should be paid to the tooth inclination deformations for the early detection of the initial crack damage. Besides, the spatial crack with non-uniform crack depth will lead to unevenness of the dynamic load distribution on the cracked tooth flank. Tilting motions can therefore be excited whenever the cracked tooth comes into the mesh.
- The nonlinear elliptical contact patterns do affect the excitations due to spalls especially for spalls with small size and gear pairs running under heavy load. The proposed model considering the effect of the nonlinear elliptical contact patterns by introducing modification coefficients can yield more realistic and accurate results.