变刚度轴承-碰摩转子机动飞行动力学响应

Dynamic response of maneuvering flight friction rotor with variable stiffness bearing

摘要:

为研究机动飞行状态下高速滚动轴承-转子耦合系统非线性动力学特性,利用有限元方法建立爬升-俯冲机动飞行状态下含滚动轴承时变刚度的轴承-碰摩转子系统数学模型,并利用Newmark-β积分法对系统动力学方程进行求解. 模型中考虑了滚动轴承时变刚度与转子非线性动力学特性之间的相互影响,分析了转子偏心及滚动轴承径向间隙的影响. 求解模型得到了系统在不同状态下的时域图、频域图及分岔图等,并以此为依据对高速滚动轴承刚度的时变特性、轴承刚度与转子动力学状态的相互影响、轴承-转子系统非线性特性、机动飞行状态对系统的影响及含碰摩故障的转子系统在机动飞行状态下的动力学响应进行了分析. 研究结果表明:轴承刚度的时变特性与转子系统的动力学特性密切相关,是限制转子系统最高转速的因素之一；机动载荷会使转子系统产生复杂的非线性动力学特性,但当系统转速较低时,机动载荷的引入能一定程度上提高系统稳定性；随着碰摩刚度的增大,系统稳定运动区间减小.

Abstract:

To study the nonlinear dynamic characteristics of high-speed rolling bearing-rotor coupling system in maneuvering flight, the mathematical model of bearing-rub-impact rotor system with time-varying rigidity of rolling bearings in climbing-diving maneuvering flight was established by using finite element method, and the dynamic equation of the system was solved by Newmark-β integral method. The interaction between the time-varying stiffness of rolling bearings and the non-linear dynamic characteristics of rotor is considered in this model, as well as the influence of the eccentricity of rotor and the radial clearance of rolling bearings. By solving the model, the time-domain diagram, frequency-domain diagram and bifurcation diagram of the system under different states are obtained. Based on these, the time-varying characteristics of the stiffness of high-speed rolling bearings, the interaction between the stiffness of bearings and the dynamic state of rotor, the non-linear characteristics of the bearing-rotor system, the influence of the maneuvering flight state on the system and the dynamic response of rotor system with rub-impact fault in maneuvering flight are analyzed. The results show that the time-varying characteristics of bearing stiffness, which is one of the factors restricting the maximum speed of the rotor system, is closely related to the dynamic characteristics of the rotor system. Because of the maneuvering load, the complex non-linear dynamic characteristics will be generated in the rotor system, but when the speed of the system is low, the stability of the system will be improved to some extent due to the introduction of maneuvering loads. The stable motion interval decreases with the increase of rub-impact stiffness.