Thermal-EHL tribodynamic analysis of a spur-gear pair, using correction factors

Abstract

A thermal-tribodynamic model was developed to study the produced vibrations in a pair of spur gears, considering rough anisotropic tooth surfaces, the use of Newtonian and non-Newtonian lubricants, and friction induced temperature effects. It consists of two sub-models, the contact model and the dynamic model. Outputs of the contact model for each pair of the meshing gears’ teeth are their respective contact stiffnesses and produced friction forces. The load-sharing method of Gelinck and DJ Schipper was used to avoid solving the complex and computationally expensive Reynolds equation. Correction factors were applied to the calculated lubricant thickness to account for the aforementioned phenomena. The dynamic response is determined by solving the equations of motion represented in state-space using the fourth-order Runge-Kutta numerical method. The total gear meshing stiffness and elasticities of bearings and shafts are modelled as forces from equivalent compression and torsional springs. For the total gear meshing stiffness, in addition to the commonly used terms and the contact stiffness, the structural coupling root-fillet stiffnesses of neighboring meshing teeth of each gear are also considered. These terms account for the deformation/movement of one tooth when force is exerted on an adjacent tooth. The effect of rotational speed, load, gear ratio, surface roughness, different lubricants, surface anisotropy coefficients, and oil bath temperature was also evaluated.