A numerical study on the performance of straight bevel gears operating under mixed lubrication regime

•A model is developed for bevel gears operating under mixed-lubrication regime.•A parametric study on the effect of different parameters has been conducted.•The higher is the hardness, the larger is the asperities capability to bear the load.•The proposed model has an acceptable accuracy and short execution time.

A model has been developed for predicting the film thickness and friction coefficient under the mixed-lubrication regime in straight bevel gears. Each pair of straight bevel gear teeth is replaced with multiple pairs of spur gear teeth using the Tredgold approximation, and the transmitted load and radii of curvature are accordingly evaluated. The bevel gears' performance is predicted by employing the load-sharing concept with the consideration of elastic, elasto-plastic and plastic deformation for asperities. The effect of parameters such as load, roughness, hardness, and rolling speed on the performance of the gear system is investigated. It has been shown that under the reported operating conditions, increasing the surface roughness to values higher than 0.5 μm results in a shift of lubrication regime from elastohydrodynamic regime to mixed-elastohydrodynamic regime.