A numerical model to calculate Elastohydrodynamic (EHL) properties in involute spur gears

Abstract

This paper presents a modified numerical model for Elastohydrodynamic lubrication (EHL) calculations of involute spur gears. This model considers the fluid as a Newtonian fluid. The main study performs on gear EHL properties along path of contact (POC). Using this study, the minimum film thickness and maximum pressure value as well complete film geometry and pressure distribution could be obtained for various applicable purposes. This study also uses a full numerical model for both gear load calculations and EHL calculations instead of experimental, approximation or analytical-experimental equations. Numerical method lets the model to calculate all required data without any limitations about the validity rang of experimental and analytical-experimental equations. In order to explain the process completely, paper firstly reviews a mathematical model to calculate the load distribution, single contact stiffness and meshing stiffness, transmission error and path of contact under load without using finite element method and in shortest time. Then a numerical method presented to solve the mathematical model using a double iteration flowchart to close the problem. This model is flexible to adapt for any modification in spur gear profile geometry. In addition to the gear load model, a modified and accelerated EHL numerical method reviewed to be utilized in this paper. The model for load distribution presents a realistic calculation for current study and modified EHL model helps to do calculations more exactly in shortest time. Finally the results of full model (that utilizes the two old models) will discuss and compared with previous methods.