黏弹减摆器非线性特性对直升机前飞空中共振的影响分析

Analysis of the Effect of Nonlinear Characteristics of Elastomeric Lag Damper on Helicopter Air Resonance in Forward Flight

提出了一种基于复模量的黏弹减摆器非线性 VKS改进模型,得到了减摆器单频及双频条件下复模量随动幅值变化的非线性特性;采用Floquet传递矩阵法计算了某直升机摆振后退型模态阻尼随前进比的变化。结果表明:直升机前飞时减摆器处于双频工作状态,与悬停时相比,空载及满载时耗能模量分别下降了50%及60%左右;从悬停转入前飞,空载时摆振后退型模态阻尼下降30%、满载时下降37%左右。

An improved nonlinear VKS model of an elastomeric lag damper based on complex modulus is presented in order to predict its nonlinear characteristics with respect to dynamic amplitude undergoing single and dual frequency excitations. The regressive lag modal damping with respect to advance ratio is resolved by Floquet transform matrix technology. Compared with hovering flight conditions, the complex modulus of elastomeric lag damper is significantly reduced in forward flight arising from the damper undergoing dual frequency motion. For light and heavy load conditions, the loss mode have about, respectively, 50%and 60% decrements in forward flight in comparison with hovering flight. Consequently, as helicopter flies from hovering to forward flight, the regressive lag modal damping has about 30% decrement for light load condition and about 37% decrement for heavy load condition.