带挤压油膜阻尼器的柔性转子非线性响应的Duffing特性分析

STUDY ON NONLINEAR DUFFING CHARACTERISTICS OF FLEXIBLE ROTOR WITH SFDB

本文导出柔性转子—同心型挤压油膜阻尼器系统稳态响应的骨架曲线及振幅界限曲线。分析系统幅频曲线、骨架曲线及振幅界限曲线之间的关系及其对双稳态响应的影响,说明附加分枝解产生的可能性,证叫对简单Jeffcott转子,系统的频响曲线总是具有硬特性,油膜力的引入并不改变原系统的临界点。且双稳态在转速比Ω<1及Ω>1的区间内都可能发生。

It is demonstrated theoretically and numerically that the flexible rotor-centralized squeeze film damper bearings (SFDB) system with multiple degrees of freedom has the nonlinear characteristics similar to those of the Duffing equation of one degree of freedom. The bcne curve and amplitude limit curve of the amplitude-frequency response curve of the system are derived. The relations among tne abuve three curves and their effects on bistable response are analyzed. It is found that the number of the intersection points of the bone curve with the amplitude limit curve determines the nonlinear forms of the system responses, and the amplitude limit curve is tangential to the amplitude-frequency response curve at the intersection point. Thus it is revealed how the Duffing and bifurcation nonlinear responses are formed. It is also proved that the squeeze film force will not change the rigid critical speed of the original system, but make the amplitude-frequency response curve de-1 fleet. This deflection always has the characteristics of hard spring,that is, the amplitude-frequency response curve will deflect in the direction of larger rotating speed. When this deflection reaches a certain degree, the bistable response occurs and it may appear in the both sides of the undamped rigid critical speed of the system.