Characteristics Research Of Shaft Vibration In Special Conditions

In recent years, the torsional vibration calculation and test methods are maturing.Correspondingly, shaft design and testing standards are becoming increasingly robust.However,there are special conditions with no express provision but constant accident. In this paper, aimed to several special conditions, the characteristics of the shaft were analyzed, so as to decrease the risk of shaft safe.First, emergency diesel generators, widely used in nuclear power plants, were used as an research object. Free vibration and forced vibration were calculated. The natural frequency provided a reference for setting speed restricted area. As for forced vibration, the focus of this analysis was the short-circuit fault conditions. By comparing the results of different excitation forces and damping parameters,it can be seen that the short circuit incentive and diesel motivation must be integrated. In addition, by adjusting the coupling and the flywheel, the unit has been optimized.Secondly, the research was based on the phenomena that actual axial fans were tested a different value in the torsional vibration test from the Traditional torsional vibration calculation. Then in the lateral vibration calculation and test, the same value was found. Thus,presumably a torsion-lateral coupling vibration produced due to the shaft unbalance. The nonlinear equations of motion was established. The results explained the phenomena that appeared in the experiment.Thirdly, the effect of gear meshing stiffness on the torsional vibration, lateral vibration and coupling of the two vibration was analyzed. In traditional algorithms, the gear pair was considered as rigid contact and two gears were equivalent according to the speed ratio. This paper considered the gear meshing stiffness and established the shaft finite element model.The natural characteristics of torsional vibration, lateral vibration and the coupling vibration were compared and analyzed. Besides, the gear transmission bench was designed and improved. The natural frequencies of the lateral and torsional vibration were tested.According to the test,the correctness of the model was verified. The controlled torque was applied to the shaft. Through tests, the presence of the coupling between the torsional and lateral vibration was verified.The analysis method of the torsional vibration of the diesel generator shaft in the short circuit condition has been applied in the project. The coupled lateral and torsional vibration model, built in the thesis, can provide quantitative and semi-quantitative theoretical explanation of phenomena that appear in the project.