| The water lubricated stern tube bearing is a very important supporting part of the ship propulsion system. Its working reliability life will directly affect the safe navigation, covert performance and operating costs of ship. The study on the reliability life of the ship water lubricated stern tube bearing is crucial to ensure the operational safety and reduce the cost. In this study, the factors are analyzed which affect the reliability life of the ship water lubricated stern tube bearing. Then, its reliability life is investigated from two points of view which are the wear life and the fatigue life. At last, the wear tests are conducted on the stern tube bearing tester to validate the reliability life models.The formation mechanism and bearing mechanism of the lubricating water film of the water lubricated rubber stern tube bearing are analyzed firstly. Based on the experimental phenomenon and data from the wear tests on the stern tube bearing tester, the levels of the factors are classified which affect the reliability life of the ship water lubricated stern tube bearing using analytic hierarchy process (AHP). The important factors, including the load, speed, particle, temperature, structure of stern tube bearing and the shafting alignment are analyzed to describe their effects.The reliability life of the water lubricated rubber stern tube bearing was investigated from two points of view which are the wear life and the fatigue life. The wear characteristics of the water lubricated stern tube bearing are described and four mathematical models, which are the average life model, reliability life model, fuzzy reliability life model and semi-experiential formula model, are established to assess the wear reliability life of the ship water lubricated stern tube bearing system based on the relationship between the wear rate of the stern tube bearing and the maximum allowable gap. The example shows that, the reliability life model and fuzzy reliability life model can reflect the asymptotic behavior of worn out failure of the water lubricated stern bearing pairs. The reliability which is got by the fuzzy reliability life model is the most conservative, and it can ensure the operational safety of the ship stern bearing on the maximum extent possible.The fatigue life model of the water lubricated rubber stern tube bearing is investigated using MSC. Patran. After loading the boundary conditions, the neutral file will be got by MSC. Nastran, and was imported into MSC. Fatigue to discuss the fatigue life of the water lubricated rubber stern tube bearing. The analysis shows that the local fatigue life of the bearing plate of the rubber stern tube bearing may be decided by the local load. It can be seen that the local fatigue life will reduce with the increase of the local load.The reliability life of the water lubricated rubber stern tube bearing was investigated from two points of view which are the wear life and the fatigue life. It is believed that the knowledge gained in this study will provide the theoretical data for assessment of ship water lubricated stern bearing and guides for when repair or change the ship water lubricated stern tube bearing in shipping service industries. |
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