Methods for calculating the resource of journal bearings at early stages of designing piston and rotary machines

Ensuring the required level of reliability of machines and mechanisms at the design stage has always been relevant. For this, at different stages of design, a wide range of specialized software is used, which is based on mathematical models, methods and techniques for calculating individual mates of machine parts. Plain bearings, as a rule, are interfaces that limit the reliability and service life of machines, since bearing failures lead to a stop of machines and production processes. The problem of forecasting and ensuring the technical resource of machines is becoming increasingly important in connection with the increase in their load on modern machines (in particular, internal combustion engines). This article describes a methodology for calculating the resource of hydrodynamic plain bearings, based on the joint solution of hydrodynamic and contact problems. The basis of the technique and its distinctive feature is the mathematical model of the viscosity of the lubricant, which reflects the phenomenon of the formation and destruction of the adsorption boundary layer on the bearing friction surfaces. The result of solving the hydrodynamic problem for a plain bearing is a set of interrelated hydromechanical characteristics. The minimum thickness of the lubricant layer and its distribution along the angular coordinate or during the loading cycle, the parameters of the roughness of the bearing surfaces are key for calculating the wear rate and bearing life. An example of the practical application of the technique for assessing the effect of individual antiwear properties of engine oil on the wear rate of the connecting rod bearing of the crankshaft of the KamAZ-740 engine, as well as the effect of the liner surface roughness on the bearing load capacity is presented. Further directions of the development of the technique are noted: the assessment of abrasive wear of the bearing, the assessment of the fatigue life of the liner surface, as well as the development of algorithms for constructing the bearing wear curve.