Conformal Contact Model And Wear Life Prediction For Spherical Plain Bearings

The self-lubricating spherical plain bearings are widely used in critical places such as the structures, transmission and control systems of weapon equipments. Major accidents would happen if failures occur in bearings. They have great influence on making sure the sophisticated weapon equipments serving with reliability and safety. Researches on the contact mechanics and service life of spherical plain bearings have great significant to improve the level of domestication.With the support of the project from the National Natural Science Foundation of China, this dissertation systematically investigates basic theories about contact and service life prediction of spherical plain bearings in aspects of conformal contact mechanics, accelerated test modeling and physics-of-failure. Firstly, this paper proposed model for elastic spherical contact, based on which established conformal contact model for pressure distribution in spherical plain bearings then. Afterwards, physics-of-failure model for self-lubricating bearings was put forward by combining sliding wear theories. Additionally, different accelerated test modeling and analyzing approaches were investigated to predict the wear life. The researches in this thesis will support designs and analyses of spherical plain bearings. The main contents are as follows:1. Both analytical and numerical methods were combined to propose a solution for frictionless contact of elastic spherical surfaces. This new model is not limited to elastic half-space as classical models are, and can be used to accurately calculating the contact pressure distribution in conformal contact and non-conformal contact of spherical surfaces. Abundant three-dimensional(3D) finite element(FE) analyses in ABAQUS coving different materials and structures proved the validity and universality of the model. Complex relationships between contact parameters were quantitatively analyzed using the new model.2. Based on the universal model of complete spherical surfaces, a new accurate analytical solution for calculating the conformal contact pressure in spherical plain bearings was proposed with equivalent force principle. This study investigated extensive 3D finite element(FE) models of bearings verified by optical experiments and then further improved. FE models verified that the theoretical model can precisely describe the contact pressure distribution in radical direction. The phenomena and laws of free-edge effect were investigated with numerical methods.3. Based on the conformal contact theoretical model of spherical plain bearings, this study established physics-of-failure(Po F) model with combination of sliding wear calculation methods. The method of analyzing linearly by stages(ALS) and inflexions identification algorithm for dynamic nonlinear wear process were proposed. Then, wear life calculation methods were provided.4. Accelerated tests of self-lubricating spherical plain bearings with PTFE fabric liner were carried out. ALS method and Po F approach were individually used to analyze the experiment data, with which this paper established corresponding accelerated model of wear rate and wear constant to predict wear life of self-lubricating spherical plain bearings. Researches indicated that the Po F method can explain the non-linear process of wear more deeply and accurately, and it can also provide the optimal prediction result.