主动电磁轴承失效后转子坠落在备用轴承过程中的非线性动力学

用有限元法建立了任意个由滚动轴承组成的固定间隙备用轴承-主动电磁轴承-多盘多质量转子系统在主动电磁轴承失效前后的动力学方程,以一个多盘转子系统为例分析了主动电磁轴承失效后转子坠落在备用轴承过程中的瞬态非线性动力学特性,讨论了柔性备用轴承的支撑刚度、支撑阻尼和间隙对转子在坠落过程中动力特性的影响。结果表明采用具有较大阻尼柔性结构的备用轴承能够显著地改善转子坠落在备用轴承上的瞬态动力特性,抑制转子在坠落过程中可能出现具有较大振动和冲击力的全间隙区的涡动运动,减小转子坠落对备用轴承寿命和可靠性的影响。柔性结构备用轴承的支撑阻尼越大,支撑刚度越小,间隙越大,转子坠落后出现全间隙区涡动运动的可能性越小。

NONLINEAR DYNAMICS OF ROTOR DROP ON ROLLING ELEMENT BACKUP BEARINGS AFTER ACTIVE MAGNETIC BEARINGS FAILURE

Dynamical equations of a multi-disk multi-mass flexible rotor supported on active magnetic bearings drop on flexible rolling element backup bearings during power failure are developed by the finial element method, the transient nonlinear dynamics of the rotor drop on the backup bearings are analyzed on a multi-disk multi-mass flexible rotor and the influence of support stiffness, support damping and radial clearance of the flexible backup bearings on the transient behavior of the rotor is examined. It is shown the rolling element backup bearing with flexibility and more damping can greatly improve the dynamic behavior of a rotor drop on rolling element backup bearings, suppress the full clearance whirl motion with a large rotor vibration and impact force acted on the backup bearings, and decrease the effect of rotor drop on the life-time and reliability of backup bearings. The higher the support damping, or the smaller the support stiffness, or the larger the backup bearing's clearance, the less the possibility for occurring the full clearance whirl motion is.