The influence of non-linearly variable normal load on the resonant vibration of shrouded blade

Introducing friction damping devices in blade structures is an effective measure to reduce the failure rate of aero-engine. The component motion perpendicular to contact surface leads the normal load to vary during vibration, and phase difference of adjacent blades makes the variation non-linear. This article analyzed the influence of non-linearly variable normal load on damper's vibration-reducing effect, and deduced the formula of hysteresis curve. Using the model raised, this article calculated the vibratory response of a shrouded blade structure and compared the result with experimental data. The conclusion is that macroslip model under the condition of non-linearly variable normal load is accurate and effective in terms of predicting the vibratory response of shrouded blade structure.