【作者】 涂奉臣；

【导师】 陈照波；

【作者基本信息】 哈尔滨工业大学 ， 机械设计及理论， 2010， 博士

【摘要】 在卫星的整个寿命周期内,发射阶段是最易受到损坏的阶段。在发射阶段,卫星将受到运载火箭发动机产生的准静态推力、发动机燃烧产生的随机振动、整流罩受到的气动激励以及各级火箭分离时产生的瞬态冲击等。由于传统的星箭连接采用锥壳适配器,其刚度很大,几乎能够传递所有来自于运载火箭的载荷,这些载荷对卫星安全构成严重威胁。为降低卫星受到的来自于运载火箭的各种振动和冲击载荷,采用整星隔振是近年来新兴起的卫星隔振措施。本文针对柔性卫星整体隔振,提出一种采用磁流变阻尼技术的新型半主动隔振平台。新型整星隔振平台以特殊形状杆件作为弹性元件,杆件与上下平台之间采用固接方式。为防止整星隔振系统的横向摇晃频率过低,提出一种套筒式防摇结构。建立新型整星隔振系统的动力学模型,并利用模态截断法简化模型。采用遗传算法对整星隔振平台的结构参数进行优化设计。建立常规剪切阀式磁流变阻尼器的集中参数模型,分析常规剪切阀式磁流变阻尼器在高频振动时的硬化原理,并对高频硬化对隔振的影响进行理论分析。针对常规剪切阀式磁流变阻尼器高频动刚度很大,对高频隔振不利的情况,提出一种可应用于整星隔振平台的新型磁流变阻尼器——高频解耦型磁流变阻尼器。建立高频解耦型磁流变阻尼器的集中参数模型,分析该阻尼器的高频动态特性及低频耗能损失。根据具体隔振要求,设计高频解耦型磁流变阻尼器的结构及参数。采用有限元方法进行磁饱和分析,确定磁流变阻尼器的最大出力和最大控制电流。在分析现有各种磁流变阻尼器力学模型的前提下,在双Sigmoid模型基础上建立高频解耦型磁流变阻尼器的阻尼力模型。设计并制造高频解耦型磁流变阻尼器,对其进行性能测试与分析,并与常规磁流变阻尼器的试验结果对比,同时验证所建立的阻尼力模型的准确性。在分析振动传递率、隔振器振级落差和功率流等指标的前提下,提出加权隔振器影响系数指标,以此做为整星隔振系统的效果评价指标。以新型整星隔振系统为例,推导出利用位移阻抗表示的加权隔振器影响系数表达式。通过计算加权隔振器影响系数指标,对新型整星隔振系统进行效果预测。采用加权隔振器影响系数对柔性体进行隔振效果评价,不但表达直观,而且可实现理论分析及实测的统一。建立卫星-锥壳适配器系统和卫星-隔振平台系统的有限元模型,分析整星隔振系统在基础随机激励下的被动隔振效果,证明新型隔振平台的被动隔振效果良好。建立星箭整体的有限元模型,分析星箭耦合情况。采用对比从发动机到卫星上关键点的传递函数来分析运载火箭的刚度对整星隔振效果的影响;通过计算运载火箭的振型相关系数来分析加入新型隔振平台后对运载火箭动态特性的影响。为了对新型整星隔振系统进行半主动隔振控制,采用一种融合了模糊逻辑控制和最优控制的模糊最优控制方法。建立整星隔振系统状态方程,利用Simulink和MATLAB联合仿真来分析新型整星隔振系统采用限幅最优控制和模糊最优控制时的控制效果,同时比较采用半主动隔振控制与采用锥壳适配器时的隔振效果。设计并制造新型整星隔振平台、锥壳适配器和模拟卫星,搭建整星隔振系统,进行整星被动隔振试验及半主动隔振控制的硬件在环试验。试验结果表明:新型整星隔振系统采用模糊最优控制在低频和高频域内都能得到较好的隔振效果。更多还原

【Abstract】 The launch stage is the period with most severe dynamic environment that a spacecraft will experience during its whole mission life. At the launch stage, the spacecraft is subject to severe vibrations induced by the launch vehicle, such as the steady-state aerodynamic loads, the thrust load, and shock loads at the stage separation period. Generally, a conical adapter is employed to connect the payload and the launch vehicle. The conical adapter cannot prevent the vibration energy from being transmitted into the satellite because of its high stiffness. To protect the satellite from the severe loads, a whole-spacecraft isolation system is presented recently.In this dissertation, new semi-active whole-spacecraft vibration isolation (WSVI) platform is presented for the isolation of FY-III satellite and LM-3A launch vehicle. In the WSVI, the magneto-rheological (MR) damping technique is adopted and utilized. Special bars are presented as the elastic elements, which are fixed to the upper and lower stages. An anti-shake mechanism is proposed to enhance the lateral stiffness of the isolation system. The dynamic model of the platform is established in a simple form utilizing the mode truncation method. Furthermore, the dynamic and structural parameters are optimized by introducing the genetic algorithm.The principle of high-frequency hardening, which usually occurred in conventional shear-valve MR damper, is investigated based on the lumped-parameter model and its effects on isolation are evaluated theoretically.The large dynamic stiffness in high frequency plays a negative role in isolation; therefore, a new high-frequency decoupled MR Damper is proposed and applied to WSVIP. The lumped parameter model is derived; then the energy loss in lower frequency and dynamic properties in high frequency are analyzed. The structure and parameters are given according to the isolation requirements, while maximum output force and corresponding current are determined by magnetic circuit saturation analysis utilizing FEM. Based on the existing models of MR dampers, a parameterized dynamic model for high-frequency decoupled MR damper is given based on the Bi-Sigmoid model. The high-frequency decoupled MR dampers are manufactured and then tested to verify the mathematical model. The results are compared with the experimental results of conventional MR dampers. Generally, large damping is difficult to obtain, which is needed in the WSVI system. Therefore, a new mechanism is presented for the installation of the high-frequency decoupled MR dampers in the WSVI system.Based the analyses and comparison of conventional index, including transmission ratio, vibration level difference and power flow, a weighted impact factor is proposed for performance evaluation of WSVI. The formula of the weighted impact factor is derived for the proposed WSVI system. The formula is a function of the displacement admittance. The weighted impact factor is evaluated, and then the performance of the proposed WSVI system is predicted. The results prove that, the proposed appraisal method can unify the real measurement and theoretical analysis.Based on the finite element model of the satellite-PAF system and satellite-WSVIP, the passive isolation performance with base excitation is investigated. Numerical results prove that the proposed WSVIP can perform better. Furthermore, the satellite-launch vehicle coupled system is investigated in the same way. The transfer functions between key points in the satellite and the engine are used to evaluate effects of the rocket stiffness on the isolation performance. The correlative coefficients of the launch vehicle with and without the WSVI system are evaluated; accordingly, the effects of the additional WSVI system on the dynamic characteristics of the launch vehicle are investigated.A fuzzy optimal control method is utilized for the semi-active control of the WSVI system. The state equations are firstly established, and then the isolation performances of the WSVI system is analyzed in MATLAB/Simulink, two control method are compared, i.e. the limiting optimal control and fuzzy optimal control. Furthermore, the isolation performances of the WSVI system and the conical adapter are evaluated and compared.Finally, the PAF, the proposed WSVIP and the satellite model are designed and manufactured, and then the WSVI system is assembled. The on-loop experiments of passive and semi-active WSVI are carried out. The results prove that, by utilizing the fuzzy logic control, the proposed WSVI system is effective at both low and high frequency stage, which is coincident with theoretical analysis.更多还原