Bearing internal load analysis and fatigue life estimation based on nonlinear dynamic model of a gear system

Abstract

The bearing internal load distribution and fatigue life estimation are accomplished based on the bearing static model at present, ignoring the gear engagement. Besides, bearings are modeled as a linear spring in gear dynamic models, failing to analyze bearing internal load. This article aims to study the bearing internal load fluctuation and corresponding bearing life in gear systems. A nonlinear dynamic model of the gear-bearing system is built, considering the time-varying mesh stiffness, the static transmission error, backlash, bearing clearance, and the nonlinear bearing force. The dynamic model is capable of calculating the bearing internal load. Based on the internal load, fatigue life is acquired using the linear damage theory. The numerical results show that the gear engagement has a significant influence on the bearing internal load analysis, in which periodic fluctuation is related to the mesh frequency and shaft frequency, resulting in the bearing life affected by gear meshing. Compared with the fatigue life predicted under the bearing static model, evident deviations are observed, pointing to the significant role of the gear engagement in the analysis of fatigue life estimation.