The key points of multi-harmonic balance method

time-marching procedure of obtainning the friction force in time domain and alternating frequency-time (AFT) domain procedure were introduced. The analysis on damping effect of under-platform damper in aero-engine was investigated using a multi-harmonic balance method combined with an AFT domain procedure

showing that this method is precise and its computational efficiency is much higher than the direct integral method. Influence of the number of harmonics on forced response indicates that more harmonic components should be kept when investigating the damping effect of under-platform damper in aero-engine under wideband multi-harmonic excitation. The optimal normal contact loads of the resonant peaks induced by various excitation frequencies are different; in practice

the design parameters of the friction damper should be optimized in line with the frequency components of excitation and the requirement of vibration attenuation to obtain the minimum response in the whole frequency range.