Abstract：The First-order harmonic balance method cannot be widely used in evaluation of performances of nonlinear vibration isolation systems due to the characteristics of multi-harmonic responses. A FFT multi-harmonic balance method is proposed based on multi-harmonic balances and dominant frequencies identified by FFT. The method was applied to the typical nonlinear system’s characteristics of jump responses, coexistent motions, multi-periodic motions and quasi-periodic responses, based on which we further improved the definition for the transmissibility of nonlinear vibration isolation. Numerical experiments for the Duffing-type isolation system show that the accuracy of nonlinear response and transmissibility has been greatly improved by the proposed method. This method is widely suitable for various nonlinear dynamic systems of which the steady state consists of components with constant amplitudes and frequencies, and is an effective tool for theoretical analysis of nonlinear vibration isolation system.
2012, Vol. 31 
