Simulation of the Thermal Process in a Polymeric Slide Bearing with a Reciprocally Moving Shaft

— This study analyzes the thermal process in a radial slide bearing made of filled PTFE and used in the reciprocal movement mode. The thermal process in the bearing is described by a three-dimensional heat conduction equation in cylindrical coordinates. The influence of the swinging movement of the shaft on the nonstationary 3D temperature field was considered by the convective term of the heat equation. A simple record of the condition of frictional heat generation in the contact zone is proposed on the assumption that the bearing has a small eccentricity. To determine the nonstationary temperature field in the sliding bearing, the well-known finite difference method (FDM) was used: the FDM includes splitting by spatial variables and consists in solving unidimensional difference equations step by step. A monotonous difference scheme was used to solve the unidimensional equation against the angular coordinate with a convective term that considered the swinging movement of the shaft. The monotonous scheme allows solving the heat equation at any step in the time and angular variables. The solution proposed for choosing from the multitude of such approximate solutions is the solution with the Courant number equal to 1. An example of calculating the thermal process of the sliding bearing made of F4C20 with the following geometric dimensions is considered: a shaft radius of 0.0125, bushing radii of 0.013 and 0.016, and shaft and bearing lengths of 0.096 and 0.022 m. The computational experiments are carried out at an equal load of 2400 N and different amplitudes and frequency of oscillations. At a frequency of 1 Hz and shaft movement amplitude of 60°, periodic temperature fluctuations at an amplitude of approximately 2.5°C are noted over time. As indicated by calculations with varying heat capacity at the convective term, the temperature fluctuations are caused by the movement of the shaft. The developed calculation methods can be used as a technique for determining the kinematic conditions in which it is necessary to consider the speed of the shaft in the mathematical model of the thermal process. The results can be used in thermal friction diagnostics in real slide bearings.