Jeffcott转子碰摩的弯扭耦合振动特性分析

CHARACTERISTIC ANALYSIS ON COUPLED BENDING AND TORSIONAL VIBRATIONS OF JEFFCOTT RUBBING ROTOR SYSTEM

针对两端刚性支承的Jeffcott转子,采用库仑摩擦模型描述了碰摩力和力矩,建立了碰摩转子的非线性弯扭耦合振动微分方程。从扭振对碰摩特性的影响和扭振碰摩特征响应两个角度,进行了碰摩特性的数值分析。通过以转速比变化为参数的分岔图发现:弯振分岔图大致可分为四个复杂运动区,有无考虑扭振的分岔图都具有周期运动、拟周期运动和复杂的混沌运动形式,但它们进入和离开这些复杂运动区的路径和在复杂区内的运动形式却有所不同;而扭振分岔图与考虑弯扭耦合的弯振分岔图存在对应关系,它也可分为四个复杂运动区,也具有周期运动、拟周期运动和复杂的混沌运动等形式。文中揭示的振动特征为转子系统的状态识别与诊断提供了一条新思路。

Aiming at the vibration analysis of a Jeffcott rotor system with rigid supports, rub-impact force and moment were described based on COULOMB friction model. And the nonlinear differential equations of coupled bending and torsional vibrations of a rubbing rotor was established. Considering the influence of torsional vibration on rub-impact characteristic and in accordance with the characteristic analysis of torsional vibration, the numerical analysis was carried out. By the bifurcation diagrams of vibration amplitude with varying rotating speed, it is discovered that the diagrams can be divided into four complex sections. The two motions, i.e. the bending vibration coupled with torsion and without torsion, both possess complex chaotic motions and bifurcation phenomena besides periodic and quasi-periodic vibrations, but the paths to enter and leave the complex motions are different. The bifurcation diagram of torsional vibration is similar to that of bending vibration. It can also be divided into four complex sections. And the motions like periodic, quasi-periodic, chaotic and bifurcation still exist . Nonlinear vibration characteristics revealed in the paper supply a new approach for the condition monitoring and fault diagnosis of rotor system.