Dynamic contact behavior of high-speed bearings in control moment gyroscope considering flexible rotor effect

The control moment gyroscope (CMG), which consists of a low-speed gimbal and a high-speed rotor, is a crucial attitude adjustment device for spacecraft. The dynamic response of the system and the characteristic behavior of the flexible rotor's bearings interact to influence the CMG's output performance. A CMG dynamics model that considers rotor flexibility, rotor-gimbal coupling effects, and bearing contact behavior is developed in this paper using the finite element method (FEM) and Lagrange method. Utilizing the bearing support stiffness matrix as a medium, a 5-DOF bearing contact analysis model is used to achieve the real-time coupling of CMG system dynamics and high-speed bearing contact characteristic analysis. Experimental verification confirms the model's accuracy. The results show that the rotor's flexibility modifies the radial forces and moments distribution, which impacts the bearings' "load zones" and "non-load zones". It causes larger variations in the contact pressure, contact angle and pitch angle. While a larger preload weakens this effect. This model will benefit bearing selection, CMG's working condition design, and system output accuracy enhancement.