阶梯轴-柔性盘耦合系统振动特性分析

Vibration characteristics analysis of a stepped-shaft-flexible-disk coupling system

传统的地面旋转机械轮盘类结构刚度较大,在转子动力学分析中多将其假定为集中质量点,而在航空发动机中为了满足减重的需要,轮盘较为轻薄,其柔性不可忽略.目前针对转轴和柔性盘耦合系统振动特性的研究还较少,为了弥补这一研究的不足,本文结合假设模态法和有限单元法,采用有限元-半解析混合建模法,建立了阶梯轴-柔性盘的动力学模型,其中阶梯轴采用铁木辛柯梁模拟,柔性盘则使用半解析方法建模,基于Lagrange方程和Galerkin方法,推导出系统的运动微分方程;然后分析了在静止和旋转状态下阶梯轴-柔性盘耦合系统的固有特性,并采用ANSYS软件仿真和模型实验验证了所开发模型的有效性;最后分别在刚性盘和柔性盘假设下,求解对比了系统的幅频响应,揭示柔性盘对系统高阶振动的影响规律.

Disk-like structures have large stiffness for the subaerial rotating machine, which are commonly assumed as lumped-mass points for the traditional rotor dynamic analysis. In order to reduce the weight in aero engine, the wheel disk is relatively thin and flexible for which their flexibility cannot be ignored. At present, there are few researches on the vibration characteristics of the rotating-shaftflexible-disk coupling system. In order to make up for the deficiency of the present research, this paper combines the assumed mode method with the finite element (FE) method, and adopts the FE-semi-analytical method to establish the dynamic model of stepped-shaft-flexible-disk coupling system. In the proposed model, the stepped shaft was simulated by Timoshenko beam, and the flexible disks were modeled using semi-analytical method. The Lagrange equation and the Galerkin method are used to derive the differential equations of motion of the system. The natural frequencies of the system are calculated under stationary and rotating conditions, and ANSYS software simulations and experiments are used to verify the proposed model. Finally, the frequency-responses are compared under the assumptions of rigid and flexible disks, respectively. The effects of flexible disk on the high-order vibration of the system are revealed.