Prediction of Durability of the Coatings of High-Loaded Friction Hinge Joints

Improvement of the durability of high-loaded friction joints, which operate under demanding conditions, remains a topical issue in mechanical engineering. Critical specific pressure at which the movable joint retains its operability and the amount of damage such as linear wear are among the limiting technical parameters of antifriction coatings. In order to estimate service life of the coatings, the paper proposes the computational and experimental model for the failure of coatings in high-loaded friction hinge joints. The proposed failure model is based on the consideration of non-uniformity of pressures between the coatings and evaluation of the operability of coatings in the hinge joints using the limit value of specific pressures at which the joint retains all its functional parameters. It is demonstrated that with the linear wear increase the angle of contract decreases, and the maximum value of specific load becomes higher, accordingly. The technique that has been developed to evaluate the average durability of the coatings allowed us to assess the impact of radial clearances and clearances formed during operation on the durability of movable joints. It is shown that the initial clearance has a noticeable effect on the durability of movable joints. For example, its change from 0.03 to 0.18 (with the linear wear being the same) leads to the reduction of the joint durability by 15…25%. The results obtained allow us to specify the coatings, providing the desired service life and significantly lower spread of the coating failures in various structural units, at the design stage.