Research On Methods Of Accelerated Reliability Demonstration For Spherical Plain Bearing Based On Gamma Process

Spherical plain bearing(SPB) is a kind of special-structured sliding bearings. With the characteristics of simple structure, large load capacity and self-aligning, it is widely applied in aerospace, mechanism, and other fields of engineering. Because of continually wear abrasion during its working time, SPB usually fails with excess radial clearance. Its failure will make the manipulate unit decrease accuracy or lose control, sometimes even causes a catastrophe hazard in the whole equipment system. Reliability demonstration could demonstrate whether SPB reliability reaches required reliability standard by testing, which ensures the finished products satisfy the established reliability demand. Therefore, it’s of great significance for the safety function of equipments.The mainly factor lead to failure is abrasion. Under normal conditions, SPB functions a long period of time before it fails. In real applications, traditional reliability demonstration methods can hardly be used to demonstrate reliability targets of SPB. Therefore, reliability demonstrataion methods based on accelerated degradation testing technology need to be introduced to solve the efficiency problem. In this dissertation, methods for accelerated reliability demonstration(ARD) based on Gamma process are researched, by introducing Gamma process as the degradation model, which provides technical support for reliability demonstration of SPB. The main contributions are summarized as follows:(1) Degradation process of SPB is analyzed systematically with probing failure mechanism. Then degradation path models and acceleration models for ARD testing of SPB are established. And the K-S test method for Gamma process is proposed.(2) Designing methods of ARD test plan based on Gamma process are proposed. By obtaining prior information and translating reliability reliability targets, ARD test plan is designed. Simulation turns out that when reliability of products with monotonic degradation process is demonstrated using the proposed method, the test duration is shorter and test result is more believable.(3) BS distribution is introduced to describe cumulative distribution of products. Optimazation problem of reliability demonstration test plan is depicted and corresponding optimization model is established. The optimal design of test plan is researched, which lays a good foundation for the ARD test of SPB. Simulation turns out that optimal test plan is effective on increasing the accuracy of demonstration.(4) ARD test is carried out in some SPB, and the proposed reliability targets are demonstrated. The demonstration result proves that selecting Gamma process as the model describing degradation process is accurate and reasonable. Furthermore, considering the deviation of prior information and optimizing test plan are more practicable, and obtained demonstration result is more precise, in which the method is validated and illustrated.In summary, this dissertation carries systematically research on degradation modeling and test plan designing approaches in ARD of SPB, by theoretical analysis, simulation and application. On the basis above, the methods of accelerated reliability demonstration for spherical plain bearing based on Gamma process are proposed. The research results are meaningful for applying accelerated testing technique to reliability demonstration of SPB.