Research On Friction-induced Vibration Of Marine Water-lubricated Rubber Stern Tube Bearing

Stern tube bearing is an important part of marine propulsion system. But under special working conditions of low-speed, heavy duty, partial high-temperature and bad lubrication, abnormal vibration and low radiation squeal occurs and easily causes low-frequency quaver and high-frequency squeal in a marine. In this paper, based on the research object of the marine water lubricated rubber bearing, applying analogue simulation and laboratory simulation test it studies the shaft bearing structure dynamics and the rubber stern tube bearing friction-induced vibration. What’s more, the interfacial contact characteristics and other aspects of the theoretical research and experimental analysis are being in contrast to each other. The main work and domain conclusions are as follows:(1) The influence of the rubber sample surface structure on friction-induced vibration effect was analysized. Through MMW-1friction and wear test it found that different surface structures corresponding to different friction-induced vibration critical speed, which resulted in the changing of friction coefficient. By comparing of macroscopic and microscopic analysis, it found that the difference of the rubber sample surface structure had great influence on stick-slip effect. If there were water tank structures on the surface, it was easy to cause friction-induced vibration.(2) Selecting the aft bearing as the research object.Through the establishment of the mathematical model and dynamic equations for numerical calculation, some related formulas were deduced and analyzed. There the rubber bearing vibration mechanism was investigated and the influence factors of friction-induced vibration were discussed and studied too. As a result, it found that the stick-slip vibration was the premise condition when there appeared friction-induced vibration phenomena.(3) Based on combing the rotor dynamics theory and the vibration theory, the stern tube bearing vibration equation was established. Furether more, theoretical calculation and simulation analysis on the natural frequency of the stern tube bearing and the working conditions on influence of friction-induced vibration were carried out effectively simultaneously. Through the mechanical analysis of the bearing it discussed the friction-induced vibration of the stern tube bearing during the operation stage. By carrying out the bench test it validated the validity of the friction-induced vibration model yet.(4) Through the finite element software ANSYS analysis and multi-body dynamics software ADAMS it could study the process of the development and formation of friction-induced vibration. The influence of temperature, speed and loading on friction-induced vibration effect was improperly discussed. Because the rubber material was sensitive to high temperature, the surface activity of the rubber material was increased synchronously as the temperature increased. Then the critical speed of friction-induced vibration increased gradually. The rotational speed was the key factor that affecting the friction-induced vibration of the stern tube bearing. In the conditions of low speed and heavy duty, the flume distribution had great influence on the operation of the bearing that under low speed. Under heavy duty the friction-induced vibration phenomena of the bearing was more obvious because the stick-slip motion of the relative speed was increased. Therefore, it was easy to generate vibration. The response of the stern tube bearing to friction-induced vibration under fluctuation of the loading was analysized. The simulation results were in accordance with the experimental results.(5) Research on water-lubricated rubber stern tube bearing tribological performance test and vibration test were to be carried out. The test results showed that friction-induced vibration of the rubber bearing had much to do with temperature, loading, speed and surface struntures. Moreover, the research results had profound guiding significance to the engineering application of stern tube bearing. Under the same working conditions, if the temperature got rise, the friction-induced vibration got obvious then. With the increase of the loading, the friction-induced vibration also gradually got violent. Application of the friction-speed negative damping theory could explain the friction vibration phenomenon well. And with the increase of speed, the friction-induced vibration only appeared in a certain speed range. Beyond the valid speed range, the friction-induced vibration gradually disappeared.