Research On Life Prediction For Spherical Plain Bearing Based On Accelerated Degradation Testing

Because of the characteristics of simple structure, large load capacity andself-aligning, spherical plain bearing is widely applied in weapon equipment andaerospace, such as spherical plain bearing in auto bank unit of helicopter. Duringworking, the spherical plain bearing is in the state of high-frequency. The event of itsfailure will result in helicopter crash. Therefore, the research on life prediction ofspherical plain bearing has important significance for design, maintenance planning, lifeextension and remanufacturing. At present, highly efficient and accurate predictionmethods are quietiy lack, because the wear failure course of spherical plain bearing isvery slow. Accelerated degradation tests are usually used to provide reliable ways to lifeprediction, for the advantage of high efficient and large initial lead. In this thesis, a lifemodel of spherical plain bearing is established based on the deep analysis of its failuremechanism. And then, the accelerated degradation model of spherical plain bearing isbuilt with the accelerated degradation theory, and the life prediction of spherical plainbearing is presented. At last, a test object is taken to the accelerated degradation test soas to verify the prediction method. The main contents of this thesis include:(1) The working failure mechanism of spherical plain bearing is analyzed with thefailure modes and the curve of failure to time.(2) The multi-asperities contact model and statistical model are established basedon multi-asperities contact theory. The maximum shear stress in the case ofmulti-asperities contact for the two models is solved. And then, based on correspondingmethod for calculating casing wear, the wear life model of spherical plain bearing isderived.(3) According to the wear life model of spherical plain bearing, suitabledegradation model is selected. And accelerated model of accelerated degradation test forspherical plain bearing is established. The analysis method for constant and steppingaccelerated degradation test data of life model of bearing wear based on multi-asperitiescontact is given, and corresponding data analysis is also presented.(4) Under the working situation of the spherical plain bearing of pitch-change-linkin auto bank unit of a certain helicopter, SKF SALKB8F is taken as the test object. Theconditions are analyzed and appropriate test platform parameters are determined. Anaccelerated degradation test scheme for the spherical plain bearing is designed topresent the test. And then, based on the analysis of test data, life of the spherical plainbearing is predicted.In summary, in this thesis, the failure mechanism of spherical plain bearing isanalyzed and a life model of the spherical plain bearing is established. The accelerateddegradation test method for the spherical plain bearing is given and verified by corresponding test. The research results can provide the theoretical and technologicalbasement for the life prediction of spherical plain bearing based on accelerateddegradation test, meanwhile they are very useful in the further research of life predictionfor spherical plain bearing.