Simulation of the tribological properties of motor oils by the results of laboratory tests

Abstract

The purpose of this paper is to present a study aimed at creating a calculation-experimental method for calculating the wear of lubricated friction units of machines based on a two-factor wear model (contact pressure – sliding velocity) with identification of their wear resistance parameters. To achieve this purpose it was necessary to obtain theoretical dependences for identification of wear resistance parameters in the wear models based on laboratory tests with various geometrical contact diagrams of lubricated samples. Analysis of known studies has shown that existing approaches required solution of complex systems of integral-differential equations or numerical methods that are unacceptable in the engineering practice. In this study a model of the wear of lubricated friction units of machines in conditions of boundary friction was obtained in a form of dependence of the wear rate on the dimensionless complexes of contact pressure and sliding velocity. The basis was the solution of the inverse wear of the contact problem for various geometrical schemes of contact. The contact diagrams corresponded to the actual forms of contact of the friction units of the machines: rolling bearings and sliding bearings, gears and others. The following equations were taken as the defining equations: the equilibrium equation in the contact, the continuity equation in the contact, and the approximating experimental dependence for the wear of materials. As a result of the solution, simple algebraic formulas for calculating and identifying the parameters of the patterns of wear have been obtained. It was found that the installation has been developed for tests by means of program Solid Works and the numerical algorithm of the decision of a task on the basis of program MathCad. The findings of the study contribute explain the influence of determining factors of sliding velocity and load on bearing wear. The practical value of the research is that the obtained results were recommended for predicting wear of lubricated friction units of engines at the design stage and optimizing their design and operational parameters.