【作者】 陈阳；

【导师】 方勃教；

【作者基本信息】 哈尔滨工业大学 ， 一般力学与力学基础， 2010， 博士

【摘要】 在卫星升空过程中,其所处动力学环境非常恶劣。为了保证卫星不受破坏,应用整星隔振技术对卫星进行保护,提高卫星发射成功率。本文以粘弹性材料为研究对象,研究隔振系统的参数设计以及可靠性方法在隔振技术中的应用,从动力学角度研究了粘弹性材料对柔性卫星隔振系统的影响。具体完成的主要研究工作如下:研究了长径比大的整星系统横纵向固有频率比的控制问题。建立了卫星-适配器等效动力学模型,通过解析方法证明了增大锥壳适配器的高度和减小锥壳适配器的锥角都可以增大整星系统横纵向固有频率比。在横向固有频率不降低或少降低的条件下降低纵向固有频率,满足了实际卫星隔振系统设计时对系统固有频率的要求。针对粘弹性材料的阻尼动力学特性,建立了多自由度隔振系统动力学模型。基于模态理论,发现了粘弹性材料储能刚度的增大会引起隔振系统模态损耗因子饱和的现象。通过对具有偏心质量隔振系统的建模和分析,证明了具有偏心现象的隔振系统存在横纵向耦合的结论。研究了粘弹性材料会引起隔振系统模态损耗因子饱和的现象。提出了一个描述动力学系统特征值灵敏度的新函数――振型差。根据振型差,得到了隔振系统特征值灵敏度的解析形式,论证了系统模态损耗因子的饱和机理。在粘弹性材料储能刚度会引起隔振系统模态损耗因子饱和的基础上,进一步证明了粘弹性材料损耗因子同样会引起系统模态损耗因子饱和,为保证实际工程中隔振器的正确设计提供了理论依据。针对卫星多为柔性体的现状,建立了柔性卫星隔振系统的有限元模型,研究了卫星-隔振器动力学系统的特性。根据Fourier变换方法,得到了隔振器底端到柔性卫星的传递率。通过对系统传递率的计算,证明隔振器具有良好的隔振性能。通过比较隔振系统在共振频率和反共振频率下的传递率,证明了过大的粘弹性阻尼储能刚度会限制隔振器两端的位移,抑制粘弹性阻尼器变形,从传递特性角度解释了隔振系统产生阻尼饱和现象的原因。通过引入不同阻尼系统和复杂系统的可靠性计算方法,得到了系统固有频率和阻尼设计方法,并进一步提出了粘弹性阻尼隔振系统的优化方法。通过隔振性能可靠性以及星箭耦合可靠性的计算,得到了系统固有频率的量化设计方法并证明了星箭耦合系统一定存在内共振现象。在理论研究的基础上,通过测定不同粘弹性材料储能刚度对应的模态损耗因子,从实验角度证明了柔性隔振系统存在模态损耗因子饱和现象,而且给出了实际工程设计中粘弹性材料储能刚度的设计方法,即测定系统模态损耗因子饱和时对应的粘弹性材料储能刚度临界值,将粘弹性材料储能刚度设计为稍大于临界值,当隔振器隔振性能满足实际要求时,其隔振性能会由于部分阻尼元件的失效而提高。而且通过隔振器冗余特性实验结果可以证明,少量阻尼元件失效不会影响隔振器的隔振性能。更多还原

【Abstract】 The vibration environment of spacecraft is very severe during launch. For keepingthe spacecraft safe in severe vibration environment, whole-spacecraft vibration isolation(WSVI) is applied to increase the success probability of launch. In this paper, viscoelasticmaterial (VEM) is studied, the parameters design and reliability technology are applied.The in?uence of VEM on ?exibility WSVI is studied in dynamic solution. The primaryobtained results are as follows:The lateral-longitudinal natural frequency ratio control problem of whole-spacecraftsystem is studied. The dynamic model of spacecraft and payload attaching fitting (PAF)is given. By the analytic solutions, it is proved that both to increase the height of PAF andto reduce the angle of PAF can increase the lateral-longitudinal natural frequency ratio.With no reduction of lateral natural frequency, the longitudinal natural frequency can bereduced to satisfy the requirement of actual launch.Taking the VEM as damping providing form, the multiple degree-of-freedoms(DOFs) dynamic model of vibration isolation is given and analyzed. Based on modetheory, it can be proved that the increase of VEM stiffness can cause the model loss fac-tor (MLF) saturation of vibration isolation system. By the dynamic model of vibrationisolation system, the in?uence of eccentric center of mass is discussed.Because the stiffness of VEM can cause the MLF saturation of vibration isolationsystem, a new function”mode displacement difference (MDD)”, which is an inherentfeature of vibration system, is brought in this paper. By MDD, the analytic solutions ofsystem eigenvalues and the mechanism of MLF saturation are obtained. Besides, the lossfactor of VEM can also cause the MLF saturation, which is developed from the traditionaldesign technology of vibration isolation. The conclusion is provided for the design ofvibration isolator in practice.Because the spacecraft is ?exible, the finite element model is given to discuss thedynamic feature of WSVI system. By Fourier transformation, the analytic solutions oftransmissibility is obtained. By the computation of transmissibility, the performanceof isolator is obtained. The dynamic feature is analyzed at natural frequency and anti-resonance frequency. It can be proved that the displacement difference of isolator will be limited by large stiffness of VEM. The deformation of viscoelastic damper (VED) issuppressed. The MLF saturation is proved by transmissibility.By the introduction of reliability computation method of different system and com-plex system, the design method of natural frequency and damping of WSVI system withVEM are obtained. Furthermore, the optimization method is presented. By reliabilitycomputation of performance and spacecraft and launch vehicle (LV) coupled problem,the quantization method of natural frequency design is obtained. In addition, it is provedthat there must be the resonant in the coupled system of spacecraft and LV.Based on the basic study, by the test of MLF, the MLF saturation is proved by theexperiment result. The design method of VED stiffness is given in practice. The stiffnessof VEM should be designed as a little more than the critical value which is correspondingto MLF saturation. As the performance of isolator satisfies the requirement, the vibrationisolation will be improved by the failure of VEDs. Furthermore, by the redundant featureexperiment of isolator, the failure of a small amount VEDs cannot cause the failure ofisolator.更多还原