Study On Vibration Characteristics Of Large-span Dynamic Shaft

Power shafting is the core power source of large surface ships.The power shafting has the characteristics of large span,low speed and large weight.So the dynamic vibration characteristics of large span dynamic shafting are studied in this paper.Based on finite element method and timoshenko beam theory,the dynamic model of each rotor part of power shaft system is obtained.After modeling the turbine rotor and the propulsion shaft rotor,the critical speed and modal mode are solved to lay the foundation for the subsequent calculation.For the subsequent power shafting machine modeling to do a good job.Through the above dynamic modeling of each rotor and connection relation of the dynamic shafting,the dynamic model of the main engine unit is first established,and the critical speed and modal mode modes are solved,which lays the foundation for the modeling of the whole machine.Then the dynamic model of dynamic shafting system is established,and the critical speed and modal modes of dynamic shafting system under rigid support and elastic support are simulated.Finally,the influence of unbalanced excitation force and applied position on the vibration characteristics of dynamic shafting system is analyzed,which provides theoretical basis for engineering practice.The three-dimensional model of dynamic shafting is established,and the three-dimensional model is divided into structured meshes.By setting the boundary conditions,the rated torque is applied on the main engine rotor and the tail end of the propulsion shaft is fixed to simulate the force of the transmission process of the power shafting.The static analysis of dynamic shafting model is carried out,the deformation of dynamic shafting under different torque is simulated,and the result is processed and calculated.It will lay a foundation for the analysis of the influence of misalignment on dynamic shafting vibration characteristics.Through the above research,the gear excitation force,unbalanced excitation force and misalignment excitation force are combined into the dynamic shafting.Through the simulation study on the vibration characteristics of dynamic shafting,the research on the vibration characteristics of dynamic shafting in practical engineering can provide theoretical basis.