干摩擦阻尼叶片的界面约束力描述及振动响应求解

Description of constraint force and prediction of vibration responses for dry friction damped blade

发展了一种描述复杂运动状态下界面约束力的三维干摩擦接触数值模型,该模型通过在接触界面建立多个摩擦接触点对得到多点分布的界面约束力,可以描述界面的粘滞-滑动共存状态和法向接触正压力不均匀分布。在该模型中还考虑了界面动静摩擦系数的不同和界面的各向异性。采用三维干摩擦接触数值模型和高阶谐波平衡法,计算了某真实围带阻尼结构汽轮机叶片在复杂激励下的非线性振动响应。计算出叶片振动响应在一个运动周期出现多个局部极值,呈含多谐波的周期函数。

A numerical 3D friction contact model is developed to depict the constraint force occurring on the contact surfaces of the damped blade in complex motions,which could be used to investigate the nonlinear vibration responses of the damped blade.By discretizing the contact surfaces into several contact pairs and obtaining the distributed constraint forces,the model could depict the stick-sliping state and nonuniform distribution of the normal contact force.The difference between the static friction coefficient and dynamic friction one and the anisotropy of the contact surfaces are taken into account in the model.The numerical 3D friction contact model high order harmonic balance method are combined to investigate the nonlinear vibration responses of a real turbine blade with shrouded dampers under the complex excitations.The results show that the blade vibration responses have several local maxima in one motion period,displaying multiple harmonical characteristics.