主动电磁轴承失效后转子坠落在备用轴承上的动力学

采用有限元法建立了由滚动轴承组成的具有固定间隙的备用轴承-电磁轴承-柔性转子系统在电磁轴承失效前后的动力学方程，分析了转子的初始坠落位置、转速、转子不平衡量以及备用轴承的支撑阻尼和刚度对转子在坠落过程中的瞬态动力特性的影响。结果表明，即便转子系统在工作时的振动很小，初始脱离位置对转子在坠落过程中的动力特性具有明显的影响；柔性备用轴承的采用，特别是具有较大阻尼的备用轴承，不仅可以减小电磁轴承失效后转子在坠落过程中的振动及碰撞力，而且能够抑制在长时间内具有较大振动和碰撞力的在全间隙范围内的反向回转运动；随着转子不平衡量、备用轴承的支撑刚度及转子转速的增大，在坠落过程中备用轴承所受到的碰撞力和转子在全间隙范围内出现回转运动的可能性增大。

Dynamics of rotor drop on backup bearings after active magnetic bearings failure

A dynamic model of a multi-disk flexible rotor dropping on flexible rolling element backup bearings with a fixed radial clearance before and after active magnetic bearings(AMB) failure was built by the finite element method(FEM).The influences of various parameters,such as dropping position,rotor imbalance,rotational speed,support stiffness and support damping of the backup bearing on the dropping dynamics were also examined.The rolling element backup bearing mounted on a flexible damping support can effectively reduce the rotor vibration and the impact force,and suppress the full clearance whirl motion during dropping.The dropping position in which the AMB becomes inactive has great effect on the rotor dropping dynamics even if the rotor orbit when the AMB is active is very small.The rotor must be balanced even if an online unbalance compensation is used.The smaller the support damping,or the higher the support stiffness,or the higher the rotor imbalance,or the higher the rotational speed,the more the possibility of occurrence of full clearance whirl motion with a large rotor vibration and impact force acting on the backup bearing for a long time period will be.