【作者】 梁鲁；

【导师】 黄文虎； 郑钢铁；

【作者基本信息】 哈尔滨工业大学 ， 一般力学与力学基础， 2008， 博士

【摘要】 整星减振、隔振技术能够有效地改善卫星发射过程中的振动环境。设计减振和隔振系统,必然要综合考虑其与卫星、运载火箭整体的耦合作用。无论是采用减振还是隔振技术措施,均会在一定程度上改变全箭系统的动力学特性。动力学特性的变化有可能对系统的飞行控制系统造成不利影响甚至控制失稳,尤其是低刚度隔振装置的加入有可能使星箭系统的基频大幅下降。另一方面,大型运载火箭结构的基频最低可达到1赫兹左右,并且模态密集,卫星的基频最低可达到10赫兹以下。振动抑制对象的大柔性特点也为相对独立的传统隔振系统设计、优化提出了高要求。本论文以星箭支架附加约束阻尼层和一般隔振装置为对象,研究整星减振、隔振与整星及全箭间动态特性的相互影响,从全箭的角度研究减振隔振技术方案的分析和设计。本文首先归纳总结了约束阻尼建模技术和分析方法,并根据整星减振、隔振的工程应用特点,建立了星箭连接支架和能够描述多种构型隔振平台的一般隔振装置的有限元模型和分析模型,发展了约束阻尼层结构混合坐标建模方法。并提取了描述一般隔振装置动力学特性的特征参数。本文应用矩阵特征值摄动方法,建立了约束阻尼层附加刚度和质量与星箭固有特性变化的关系,研究了附加约束阻尼层后全箭固有特性的变化。分析表明,整星减振技术措施对全箭固有频率、模态振型、振型斜率的影响均很小;星箭支架变形能占全箭模态总能量的比例是约束阻尼层阻尼贡献的重要参考量。适当降低现有支架的连接刚度,增大支架在低频模态的模态应变能比例,能够提高约束阻尼层的低频减振效果。本文建立了任意星、箭组合通过一般隔振装置连接的全箭振动传递导纳,并在此基础上推导出全箭固有频率基于导纳的非小量摄动解析解;从基于局部非小量的结构重分析思路出发,以星、箭振动传递导纳为指标,讨论整星隔振对全箭固有频率、模态振型、振型向量以及星箭振动传递特性带来的影响。研究结果表明,卫星与运载火箭的质量相差悬殊,在现有的全箭系统中用隔振装置替换原有支架,不会对运载火箭的模态振型及与控制系统设计有密切联系的振型斜率产生明显的影响。本文根据全箭横向振动传递特性与隔振装置特征参数的关系,提出了“共振-反共振相消”参数配置方法,并以此来对隔振性能进行优化。论文的最后部分详细的介绍了FY-2结构星转接锥附加约束阻尼层的整星减振技术工程实施,结合试验指出大型复杂结构阻尼减振试验中需要重点注意的现象及其成因。在整星隔振试验方面,地面试验边界条件与实际工作条件具有一定的差异,这种差异可能严重影响阻尼减振效果评价的正确性。更多还原

【Abstract】 The whole-spacecraft vibration attenuation (WSVA) and isolation (WSVI) technique could significantly reduce the launch loads on the spacecraft during the trip to the orbit. The WSVA and WSVI must be analyzed and designed in a system-level of view, accounting for its coupling with the launch vehicle (LV) and spacecraft (SC). Actually, the dynamic characteristics of the whole LV and SC system will be changed to some extent after isolation treatments, which may bring some side-effects to the flight control system, e.g. the introduction of low frequency mode by the isolation may threat the stability of the flight control. On the other aspect, the LV typically has closely-spaced flexible modes with frequencies starting as low as 1 Hertz, and the SC may have modes with frequencies starting as low as 10 Hertz. Different from the classic isolation system design, the isolation of a flexible body from another one demands a special design methodology, specifically, from system-level. This dissertation focuses on studying the problems associated with WSVA/I design and developing design methodology at the system-level.Beginning with a literature survey of damping modeling and analysis methods, with a fully consideration of specific characteristics of the WSVA/I devices, LV and SC structure, high fidelity finite element models of PAF with/without the CDL is established. A mixture coordinate modeling method is also developed for the PAF with the CDL. An mechanical model of general isolation devices are established for further analysis of whole LV/SC System.An eigenvalue-perturbation method is developed based on Gerschgorin’s Circle Theorem, and then is applied to build the relational expression of the additional stiffness/mass of CDL and the perturbed modal parameters of the whole LV/SC system. With this expression, the influence on the dynamic parameters of whole LV/SC system is studied by simulation. The results indicate that this perturbation method is efficient and accurate for the system-level analysis. It also shows that the modal parameters such as nature frequencies, modal shapes and modal shape slopes, are only slightly changed by the CDL treatment. The modal strain energy ratio of PAF to whole system is a critical variable to evaluate the contribution of the CDL to the whole system damping. As indicated by the vibration isolation theory, properly lowering the stiffness of the PAF can increase its modal strain energy ratio as well as the effectiveness of vibration attenuation in the low frequency range.With transfer functions of LV and SC coupled by WSVI device, an analytical expression of the whole system nature frequency in terms of the general WSVI devices’parameters is derived. The interrelationship between the modal parameters of whole LV/SC system and parameters of the general WSVI devices is studied. Because the LV dominates the mass of the whole coupled system, the results show that, the modal shapes and modal shape slopes, which correlate closely to the flight control system, changed insignificantly by the replacement of WSVI devices to the current PAF. In this dissertation, a“pole-zero cancellation”method is proposed to design and majorize the isolation performance, which is a parameter configuration method to eliminate a certain resonance of a certain component on the SC.Finally, a CDL engineering implementation and vibration test is introduced which is carried out on the PAF of a prototype FY-2 satellite for suppressing the load transmission to its on-board instruments. On analysis of test results, abnormal phenomenon and their root causes discovered from the test are figured out. Moreover, there are differences between the boundary conditions in the ground test and that in the actual launch. These differences may bring incorrect conclusion to the performance evaluation of damping implemented in WSVI technique.更多还原