| Rotating machinery plays an important role in the development of national economy.It has been widely used in energy,electric power,petrochemical,aerospace,among others.For rotors of aircraft engines during aircraft maneuvering and power plant reactor rotors during the event of earthquakes,the foundations of these systems may be exposed to suddenly imposed motions.In this paper,the rotation and translation of the stator and their coupling with the rotor are considered respectively,and three kinds of dynamic models are established.Based on the rotor of a centrifugal pump,the dynamic characteristics of the rotor system are analyzed.The main work of this paper is as follows:Using Rayleigh's beam model and considering moment of inertia and gyroscopic effect,a finite element model of a multiple-degrees-of-freedoms rotor-bearing system is established.The differential equation of motion of the system is derived through the Lagrange equation,and the critical speed and unbalance response of the system are obtained.In the followings,the model of the rotor-bearing system with a base excitation is formed in association with the forced vibration model.In order to consider mass,elastic deformation and other factors of the foundation,the coupled rotor-bearing-foundation model is proposed and the Newmark method is employed to calculate transient response of the system.It can be seen from the results that the displacement of the rotor is offset in the direction of excitation when the stator is uniformly accelerated.The rotational speed of the rotor and the sinusoidal excitation will change the displacement response of the rotor.There will be a combination of resonance between the rotor and the foundation.In the case that the rotation speed of the rotor is equal to the natural frequency of the foundation,the resonance phenomenon will occur.Based on the theory of theoretical mechanics and rotor dynamics,the displacement vector and velocity vector of elements in the reference frame are derived.Using the Lagrange equation,the differential equations of motion of the rotor-bearing system of the rotary foundation is obtained.The rotation of the foundation leads to additional inertial matrix,stiffness matrix,damping matrix and force vector.It can be seen from the results that the response of the rotor is changed when the rotor rotates in the direction of the rotor shaft.The rotor response changes when the foundation is in lateral rotation,and the maximum value is reached when the external excitation frequency approached the critical speed. |
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