Abstract:Intersecting shaft gear-rotor system with the structure characteristics of multi-body, different speed and axis line, which make the rotor dynamics modeling method different from coaxial rotor system, the paper adopts a idealized method that can enable the rotor system with characteristics of multi-body, different speed and axis line change into the coaxial rotor system with the same speed , then the modeling method using idealize modeling method and Finite element software DyRoBes is verified by contrast researches. Use helicopter tail drive system a typical structure of intersecting shaft gear-rotor-system as the research object, establish its idealized rotor system dynamic model, then analyze the natural frequency, torsional mode, the influence of moment of inertia of the coupling gear on the natural frequency, finally the influence of the mesh stiffness are analyzed. The results show that in the first 10 orders of natural frequency of the transmission system, except the 1st and 2nd order are coupling natural frequency, the other orders are all derived from the natural frequency of each component shaft. There is a mapping relationship between the meshing stiffness values of middle and tail reduction, and some meshing stiffness values will stimulate the maximum torsional vibration value of resonance, which should be avoided. Meshing stiffness of the middle and tail will cause changes of critical speed, especially the 1st and 2nd critical speed. Different order natural frequency has different sensitivity to change of inertia of different components. This paper studies the dynamic characteristics of intersecting shaft gear rotor system from the view of rotor dynamics, which can provide theoretical basis for the optimal design of this kind of rotor system.