On an independent subharmonic sequence for vibration isolation and suppression in a nonlinear rotor system

Independent vibrations in nonlinear systems characterize responses in solitary frequencies that provide advantages for vibration isolation. In the research, a sequence of odd-order independent subharmonic vibrations in a nonlinear flexible rotor system is released for vibration isolation and suppression. The continuous nonlinear rotor system is discretized to form special mappings for independent subharmonic vibrations. Subharmonic vibrations of order-1, 1/3 and 1/5 on the vibration chain are obtained for the illustration of the vibration sequence (e.g. S1►S1/3► S1/5►∙∙∙► S1/m (m=1,3,5, ∙∙∙)). Complex stability and bifurcations are discussed and determined for a better understanding of the nonlinear vibration sequence. The results show each subharmonic vibration is triggered by paired saddle node bifurcations and only occurs in a solitary frequency range. Global synchronous vibrations are significantly suppressed in the sequence. Unstable subharmonic vibrations are completed with prescribed accuracy. Frequency-amplitude characteristics of the independent subharmonic vibration sequence are discussed for better vibration isolation and suppression. Harmonic spectrums and phases are presented for deeper understanding of the independent vibrations. Such studies provide new perspectives of understanding complex nonlinear vibrations and suggest guidelines for next generation vibration isolation and suppression of nonlinear systems.