【作者】 金晓飞；

【导师】 沈世钊； 范峰；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2010， 博士

【摘要】 FAST(Five-hundred-meter Aperture Spherical radio Telescope)是500米口径球冠状射电望远镜,是世界上正在计划及建造中最大的单体射电望远镜,开创了建造巨型射电望远镜的新模式。反射面结构是FAST最主要部分,其本质上是一个轻型的跨度超大、形式复杂、形状实时可调的高精度索网结构。历经13年的预研究,在结构方案、形态优化、变位策略等方面取得了丰硕成果。然而在前期研究中未曾深入研究的,但是对FAST将来的建造、运行以及维护有着重要影响的结构安全与精度控制关键问题,仍亟待研究和解决。这些问题的研究不仅在FAST项目建设中有着迫切的需求,而且在类似巨型射电望远镜结构中也几乎处于空白阶段,没有参考依据,因而有着广泛应用前景,具有明确的工程应用价值和理论创新意义。本文进行了如下几方面的工作:1、FAST日照非均匀温度场模拟及效应分析综合考虑了太阳辐射作用、阴影遮挡、空气对流换热等多种影响因素,建立了FAST真实环境下的结构温度场数值模型,其中,提出了复杂地形下FAST反射面结构日照阴影分析方法;采用时程分析方法,计算了FAST反射面结构日照非均匀温度场,在此基础上,分析了日照温度场对不同位置抛物面的面形拟合均方根RMS(Root Mean Square)的影响规律。结果表明该影响不容忽视,依据结构特性和结构日照温度场特性,提出了日照作用下反射面面形精度RMS值的有效调控方法。2、FAST结构参数敏感性分析总结分析了目前各种参数敏感性分析方法的优缺点,针对FAST反射面结构特点,提出基于随机抽样和相关性的参数敏感性分析方法,其中,引入了拉丁超立方抽样方法和线性相关系数显著性检验方法,解决了敏感性分析时由于大规模结构参数的随机抽样和矩阵运算而导致的计算困难问题;依据实际情况建立了各结构参数的概率统计模型,应用本文方法进行了大量计算,得出了各结构参数随机误差对反射面面形精度RMS值的影响规律。依据敏感性分析结果,提出了结构参数精度控制建议。3、FAST结构变位疲劳性能研究针对FAST长时巡天跟踪观测和随机独立跟踪观测的工作方式,对结构变位疲劳寿命需求进行了分析,提出了长期变位疲劳应力的计算方法,并基于MATLAB和ANSYS软件编制了相应程序,提出了疲劳全寿命应力历程的等效简化方法,编制了随机、变幅应力历程的实时雨流计数程序,基于S-N试验曲线和Miner线性累积损伤准则,对结构变位疲劳寿命进行了数值计算,获得了疲劳寿命统计分布和疲劳危险区域。研究表明:考虑安全系数2.0后,FAST结构变位疲劳寿命仍满足要求。最后进行了钢绞线和钢拉杆的疲劳试验。4、FAST结构故障诊断与安全评定依据FAST反射面结构特性及其主动变位工作方式,提出结构失效故障的三种基本模式,并针对性地提出了结构故障诊断方法,实现了结构故障位置的在线诊断和失效单元的离线诊断,针对反映结构安全状态的两个主要指标——结构剩余疲劳寿命与结构静力安全储备,提出了结构安全评定方法;基于MATLAB和ANSYS软件编制相应程序,进行了数值模拟分析,验证了本文所提方法的有效性。5、FAST结构健康监测系统的开发与集成针对FAST反射面结构特点,提出了系统构成、功能和监测内容;对各类传感器进行优化选型和测点优化布置,对数据采集硬件合理选型并提出了传输布线方案;综合利用LabVIEW、MATLAB、ANSYS、Delphi等软件平台,编制结构变位分析、结构故障诊断与安全评定等的核心模块,开发设计了FAST结构健康监测集成软件系统,实现了其自动化、可视化功能。其中,监测系统已在FAST 30m模型张拉成形试验中得到应用。更多还原

【Abstract】 Five-hundred-meter aperture spherical riado telescope (FAST) is expected to be the largest telescope among those telescopes in the plan or under construction in the world. FAST pioneers a new model for constructing the giant telescope. The reflector structure as the main part of FAST is essentially a lightweight and complex cable-net structure with a super-long span and a real-time adjustable shape. Though the results in structure scheme, shape-state optimization, shape-changing strategy and etc, have been achieved during the 13-year preliminary research. However, the key issues of structural safety and accuracy control is still not studied in-depth in the previous research, and obviously, these issues will have a significant impact on the construction, running and maintenance of FAST. The research on these issues is urgent for the construction of FAST, and also has a broad application in other similar giant radio telescopes because it is nearly at blank stage for those structures. Therefore, the research is of obviously engineering applicatoin value and theoretical innovation significance, and needs in-depth study. The main contents in this paper are shown as following.1. Simulation and effect analysis of non-uniform solar temperature field of FASTThe finite element model of FAST in the actual environment for structural temperature field analysis is established, with the factors of solar radiation, shadow in surrounding environment, periodic air temperature and etc taken into consideration at the same time. The non-uniform solar temperature field is computed using the transient analysis method, and subsequently, the RMS values of fitting of the reflecting surface for working paraboloids in different locations of the spherical cap under sunshine are analyzed. The results show that the impact of the non-uniform solar temperature field on RMS values should not be ignored. Finally the control method of RMS value under sunshine is proposed according to the structural features and characteristics of the temperature field.2. Parameter sensitivity analysis of FAST structureThe advantages and disadvantages of various methods for parameter sensitivity analysis are summarized and analyzed. According to the characteristics of FAST reflector structure, the paremeter sensitivity analysis method based on random sampling and correlation is proposed, and in order to solve the calculation difficulty induced by random sampling and matrix operations of large-scale parameters, the LHS sampling method and correlation coefficient significance test method, are introduced. The probability-0statistic models of FAST structural parameters are established based on practical situation, and the influence of structural parameter random errors on RMS value is obtained by a great lot of computations. Finally, suggestions for accuracy control of structural parameters are presented.3. Shape-changing fatigue analysis of FAST structureThe requirement analysis of fatigue life is carried out according to the working mode of longtime sky survey and independent random tracing observation, and the computation method of shape-changing fatigue stresses is proposed and programmed based on sofewares of MATLAB and ANSYS. And then the simiplication method of life-cycle stress course is put forward, the realtime rainflow counting method for random and variable amplitude stress course is programmed. Subsequently, the structural fatigue life is calculated by numerical simulation based on S-N test curve and Miner linear cumulative damage method, and the statistical distribution of fatigue life and fatigue risk zone are obtained. Finally, the fatigue property of strand cable and steel rod is tested.4. Fault diagnosis and safety assessment of FAST structureThree basic modes of structural failure are presented according to the structural features and the active shape-changing work mode, and the method for structural fault diagnosis is proposed and studied to realize the on-line diagnosis of structural fault region and off-line diagnosis of failure members. The method for structural safety assessment is proposed, which is aimed at the two leading indicators of structural long-term safety, the residual fatigue life and the static safety stock. Then the two methods are programmed and validated by numerical simulation.5. Development and integration of structural health monitoring system of FASTThe frame, functions and monitored variables of the system are determined according to the characteristics of FAST reflector structure. The optimal lectotype and location of sensors are analyzed, the hardware for acquisition is selected in reason, and the transmission wiring scheme is designed. The integrated software system for health monitoring is developed with the functions of automatization and visualization, synthetically using softwares of LabVIEW, MATLAB, ANSYS, Delphi and etc, and wherein the core modules for active shape-changing analysis, structural fault diagnosis and safety assessment and ect are programmed. The monitoring system has already been applied in the stretch forming test of FAST 30m model.更多还原