Effect of sliding friction on gear noise based on a refined vibro-acoustic formulation

An improved source-path-receiver model of a single mesh geared system is developed and validated to quantify the effect of sliding friction between gear teeth on the structure-borne whine noise. The source sub-system of a spur gear pair predicts interfacial bearing forces in the line-of-action and off line-of-action directions for two whine excitations (static transmission error and sliding friction). Next, a finite element model of the gearbox with embedded bearing stiffness matrices is developed to characterize the structural paths and to calculate the surface velocity distributions. Predictions are first validated by comparing with structural modal tests and transfer function measurements from gear mesh to the housing plates. Radiated noise is then estimated by using two approximate methods, namely the Rayleigh integral method and a substitute source technique. The overall vibro-acoustic model is validated by comparing radiated sound pressure calculations with measured noise data over a range of operating torques. The proposed formulation provides an efficient analytical and computational tool to quantify the relative contribution of sliding friction to the structure-borne noise, which is found to be significant when the transmission error is minimized say via tooth modifications.