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Abstract
Reliable lubrication is essential to the life of gear transmission systems. An approach to predict the reliability of gear elastohydrodynamic lubrication (EHL) under a random input torque is proposed in this article. Firstly, a single-degree-of-freedom nonlinear stochastic dynamic model that considers backlash, a time-varying mesh stiffness, and random loads is established to obtain the probability distribution of the tooth meshing force. An EHL model is employed to obtain the relationship curve of the gear meshing force and the minimum film thickness at different positions of the active line. Then, the probability distribution of the minimum film thickness, which is the input variable of the reliability model, can subsequently be obtained by combining the probability distribution of the tooth meshing force and the meshing force–minimum film thickness curve. Finally, the reliability of the lubrication can be evaluated by the generalized stress–strength interference theory. To validate the method, an involute gear pair is analyzed, and the results show that the failure probability of full-film lubrication is high at the dedendum of the pinion and boundary lubrication would not occur. The wear condition of the gear obtained from the failure probability is consistent with observations.