Dynamics Of Flexible Rotor Described By Absolute-coordinate-based Method

In the engineering, there are rotating parts in the common machines, that is the rotor. For example, the steam turbine, the generator and electromotor regard the rotor as the main part. When the machine is working, the rotor system always causes vibration. The vibration reduces the efficiency, it may also make fracture. Therefore, applying the concept of rotor dynamics, and designing for rotor vibration characteristics of lateral vibration reasonably has been an important issue.The appearance of the absolute nodal coordinate method(ANCM) has created a new era of the multi-body system dynamics. The beam, plate and shell elements which described by absolute nodal coordinate method are isoparametric elements. As for the system equations of motion, the system mass matric remains constant and the centrifugal and coriolis forces vanish. The motion of rigid body system could be described exactly. All the above characteristics can make the absolute nodal coordinate method lead to more accurate results than the traditional methods do, especially for the flexible multibody systems with large deformation and rotation.In the article, it mainly illustrates applying the concept of rotor dynamics and considering the advantages of absolute nodal coordinate method, to get solution of rotor dynamics problems in absolute nodal coordinate method and explore the prospect of application of the method in rotor dynamics field. Firstly, the research work of rotor dynamics, Kinematics equation algorithm and development process of absolute nodal coordinate method are introduced. Secondly, the two-nodes model based on absolute nodal coordinate method of simply supported beam of circular cross section which is in three dimentional is established. And deduce the transverse vibration equation of motion of the beam model with the consideration of the gyroscopic effect. Finally, there is the numerical simulation by programming. The numerical simulation is involved in model analysis, the result is compared with the traditional finite element method, and find out the error between the two methods. In absolute nodal coordinate method, the rotate speed and length to diameter ratio are considered to analyse the influence on procession frequency. In addition, generalized-α is used to solve the eqution of motion of beam model. The amplitude frequency response curse of the beam model is matched basing on the transient response, and analyse the transformation in different speeds respectively. In conclusion, absolute nodal coordinate method is verified the correctness of the beam model in transient response.The research of issue given verifies the correctness of application of absolute nodal coordinate in rotor dynamics with the consideration of gyroscopic effect. So in the engineering, the absolute nodal coordinate method which is used to modal analysis, transient response calculation has a great application prospect.