Abstract: Considering each component’s elasticity of geared rotor system, a method to simulate the continuous engagement of gear pairs is proposed based on the contact finite analysis. The model is built by solid finite element to analyze structural vibration characteristics. By using the contact finite analysis method to simulate the engagement, the actual excitation like time-varying mesh stiffness, meshing contact can be included in the model, then more comprehensive, accurate response characteristics can be obtained. Solid finite model of a spur geared rotor system is built to simulate the dynamic engagement of gear pairs based on the contact finite element analysis method; the time-domain response of kinetic parameters such as contact force is achieved by resolving the equation of motion. The deviation of center distance, dynamic transmission error and the contact force is used to study the lateral vibration, torsional vibration, the engagement characteristic and coupling relationships of these. The results show that the elasticity of each component especially the rotors have great affection on the dynamic behavior of the system through increasing the nonlinear vibration characteristics such as bilateral impact and disengage of the gear pair.

Key words: contact finite analysis method, dynamic transmission error, geared rotor system, non-linear vibration