Study on nonlinear force transmissibility of flywheel rotor system considering periodic base motions

Abstract

This paper reports on the study of the dynamic force transmissibility (DFT) of flywheel rotor system (FRS), considering periodic base motions and nonlinear support stiffness of angular contact ball bearings (ACBBs). The energy method and Lagrange equation are adopted to deduce the base induced additional excitations, including the internal (gyroscopic and stiffness) and external excitations. The influence of combined loads and contact angle variation is introduced into the Jones formula to accurately solve for the internal load distribution and nonlinear stiffness of the ACBBs. The lateral vibration model of FRS considering base motions and ACBB nonlinear support stiffness is then established. The DFT of the system is obtained by combining the harmonic balance method and alternate frequency/time domain method. The arc length continuation method is employed to track the multi-solution region owing to bifurcation. In addition, the stability of harmonic balance solutions is determined through eigenvalue analysis in the frequency domain. Both numerical integration and comparison with literature results are used to verify the accuracy of the proposed DFT model and solution method. On the basis of these results, the effects of base motion amplitude, ACBB axial preload, and rotor damping on the DFT of the system are discussed. With the increase of radial deformation, the support stiffness of ACBB under axial preload shows “soft” and “stiff” characteristics in turn. The additional excitation caused by the base motions is the key factor determining the nonlinear characteristics of FRS. These results support designing a reasonable vibration isolation system and reducing the transmission of FRS dynamic response to the spacecraft platform.