Nonlinear couplings in a gear-shaft-bearing system

Abstract

The present work contributes to the analysis of the interactions between gears, shafts and hydrodynamic journal bearings in geared drives. In contrast to the majority of the models in the literature, the time-varying properties and nonlinearities of gears and bearings are introduced in the simulations. A finite element model is used for the shafts, and a specific gear element is used to account for nonlinear time-varying mesh stiffness as well as tooth shape deviations. The nonlinear hydrodynamic forces are computed with the Reynolds equation for finite-length journal bearings. An iterative Newmark scheme is used to solve simultaneously the motion equations for the shafts, the contact problem for the gears, and the fluid forces in the bearings. The resulting algorithm is applied to a single stage geared system with two shafts, four bearings, a pinion and a gear. Gear-bearing dynamic interactions are demonstrated through the analysis of dynamic gear loads, dynamic bearing loads and bearing displacements. The efficiency of the proposed numerical procedure, the interest of nonlinear models for hydrodynamic bearings and the influence of several parameters ruling the gear assembly are also discussed.