阻尼环对姿控飞轮高速运行时高频扰动的干摩擦阻尼动力吸振抑制机理研究

For attitude control flywheels operating at high rotational speed, the disturbance force/moment in the high frequency range 200-300Hz is one of the main vibration sources for on-orbit mircovibrations of spacecraft. By employing the mechanisms of dynamic vibration absorber and dry friction damping to dissipate energy, friction rings can effectively suppress the vibration and shock responses of flywheels in the launching phase. However, whether the friction rings can reduce the high-frequency disturbance force/moment or not is still a problem to be answered. Aimed at the problem, three aspects are considered to be investigated. Firstly, taking gyroscopic effect into consideration, establish the dynamic models of the flywheel to analyze the interaction between the poly-harmonic disturbances of mass imbalance or bearing irregularity and the structural modes, determine the mechanism of generating the high-frequency disturbance and the structural modes to be suppressed. Then, establish the nonlinear multi-degrees-of-freedom dynamic model and the nonlinear reduced finite element model of the friction rings with dry friction interfaces 饿elastically mounted on a flexible flywheel. On the one hand, without considering excitation forces, carry out complex nonlinear modal analysis to highlight the effects of dry friction damping on nonlinear modal parameters and system stability; on the other hand, conduct the solution under possible excitations to obtain the disturbance force/moment and study the local behavior of dry friction interfaces, carry out parameter analysis on design parameters of friction rings and the interfaces, clarify the influence of these parameters on disturbance force/moment suppression. Modal tests and disturbance tests on Kistler Table measurement system are carried out to verify theoretical findings and effectiveness. The investigation will provide theoretical basis and technical support for high-frequency disturbance suppression of attitude control flywheels.

姿控飞轮高速运行时产生的200-300Hz范围内的高频扰动力/力矩是航天器在轨微振动的主要激励源之一。利用动力吸振和干摩擦阻尼耗能，阻尼环在发射段能有效抑制飞轮固有模态的振动放大，但其能否抑制高频扰动是亟待回答的问题。项目针对这一问题，首先建立考虑飞轮实体模型和陀螺效应的飞轮转子动力学模型，分析不平衡激励、轴承不规则激励与飞轮模态的耦合作用，揭示扰动生成机理和飞轮模态特征；然后建立弹性支承阻尼环-干摩擦界面-飞轮的非线性多自由度等效模型和有限元缩聚动力学模型，先不考虑激励，进行复非线性模态分析，明确干摩擦阻尼对模态参数、系统稳定性的影响规律；进而求解各可能激励下的响应，获得扰动响应和干摩擦界面局部动力学行为特征，明确阻尼环和摩擦界面设计参数对扰动抑制的影响规律，指导阻尼环的优化设计。开展模态测试和飞轮运行时的扰动力/力矩测试，验证相关机理和效果，为飞轮高频扰动控制提供理论依据和技术支撑。

姿控飞轮高速运行时产生的200-300Hz范围内的高频扰动力/力矩是航天器在轨微振动的主要激励源之一。微振动导致的高精度航天器有效载荷指向精度和指向稳定度的降低是我国发展高分辨率、高精度航天器的主要瓶颈之一。项目围绕这一问题，从高频扰动力的动力学建模和扰动生成机理研究、干摩擦阻尼动力吸振多自由度动力学模型建模和扰动抑制机理研究、有限元缩聚动力学模型建模和扰动抑制影响规律研究、飞轮运行时扰动力/力矩测试和抑振机理及效果验证等4个方面开展研究。发展了可考虑转动部件三维实体模型和非线性轴承界面的频响函数综合方法用于高频扰动传递力预报；发展了基于时频域转换法和多谐波平衡法用于求解弹性支承阻尼环-干摩擦界面-飞轮高维非线性动力学系统的非线性模态和非线性动力学响应。揭示了姿控飞轮的轴向伞形模态、径向平移模态对高频扰动力的放大机制；明确了阻尼环的模态特性、阻尼环模态与姿控飞轮轴向伞形模态和径向平移模态的相互作用动力吸振机理；发现了界面干摩擦阻尼对模态阻尼比的增强机制、对粘弹性阻尼控制频带的拓宽机理、对航天高低温环境变化不敏感的特性；建立了考虑实际飞轮-弹性阻尼环多摩擦界面的阻尼环、干摩擦阻尼界面的设计方法。飞轮运行时的扰动力/力矩测试结果表明，姿控飞轮的轴向伞形模态、径向平移模态是200-300Hz内主要扰动力峰值的贡献者，阻尼环能够抑制不同转速下的特征模态放大。阻尼环干摩擦阻尼动力吸振机理可进一步应用于抑制螺旋桨同相振动模态处（类似于伞形模态）的振动传递放大。