Functions and experiment on damping mechanism of spacer

For the imperious internal demand of designing wide-chord blades of the high bypass ratio turbofan engines, the functions and design requirements of a spacer of the wide-chord blade were analyzed firstly, and the damping mechanism was revealed by the way of experimental study as well. Experimental results showed that the effect of vibration absorption of the spacer on the steady-state response of the blade under harmonic excitation was poor, while the effect under impact excitation was obvious, which reduced free vibration and cumulative fatigue damage effectively. The impact response time of the blade with a rubber spacer or a metal rubber spacer can be reduced by more than 50%. The preload of the spacer should be enough to locate the radial direction of blade steadily, decreasing the swing amplitude of blade and the mass loss by contact wear between dovetail and groove under windmilling condition. On the other hand, the flexibility of spacer should ensure that blade can swing an angle under high energy impact, so that the spacer absorbs impact energy by mean of deformation, in order to reduce the stress peak of the blade root.