【作者】 何蕊；

【导师】 王本利； 罗文波；

【作者基本信息】 哈尔滨工业大学 ， 飞行器设计， 2009， 博士

【摘要】 随着航天技术的迅速发展,大量轻型复合材料结构和机构在卫星设计中被广泛采用,由于卫星从发射到在轨飞行所经历的环境相当复杂,某些情况下出现了较强的非线性,为提高系统的可靠性,采用传统的环境试验和分析方法很难满足工程要求,本文采用随机激励的方法对结构非线性检测和特性分析进行深入的研究,并对卫星结构设计中常用的铝蜂窝夹层板进行了理论验证性的工作,并取得了较好的研究成果:给出了基于随机振动试验数据高阶统计量中双谱的结构非线性检测方法,根据检测白噪声激励下结构的输出是否为白噪声来确定结构中是否存在非线性;给出了基于混沌理论的结构非线性检测方法,该方法根据判断白噪声激励下的结构输出时间序列是否存在混沌现象,进而得到结构非线性的存在性。针对随机试验下频域中结构的非线性检测方法、非线性类型识别等特性分析问题,基于FPK变换和等效原理的线性等效方法,建立了随机激励下分别含有非线性阻尼、非线性刚度的频响等效模型,揭示了随机激励下含不同非线性系统频响函数随外激励量级的变化规律,并给出了利用此变化规律进行随机振动系统非线性检测及非线性定性方法。以卫星用铝蜂窝夹层板为试验对象,设计了随机振动试验的总体方案,利用随机振动试验数据,分别应用基于频响函数、高阶谱理论以及基于混沌理论的非线性检测方法对铝蜂窝夹层板的非线性进行了检测,揭示了试验试件的非线性存在和混沌现象;并对随机试验的混沌时间序列进行了相空间重构,通过Volterra自适应滤波器进行了动力学行为预测,通过与实际试验数据比较表明预测结果与实测结果具有良好的一致性,表明本方法的有效性。同时还提出了一种直接利用加速度形式输入输出数据的结构非线性特性分析方法,避免了数据处理过程。并分别应用基于频响函数的和基于加速度传递率非线性特性分析方法对铝蜂窝夹层板的非线性特性进行了分析,揭示了铝蜂窝夹层板的共振放大倍数随激励强度的变化规律和频率漂移现象,验证了所提非线性特性分析方法的适用性。更多还原

【Abstract】 Nowadays, with the rapidly progress of the astronautics technic, the compond material is widely used in spaceflight field. Owing to the complex environment, lots of nonlinear problems appeare. The linear method can not meet the need of identification, and the study of nonlinear is necessary. Meanwhile, the traditional mechanical environment testing can not meet the need of ensure the reliability of aerocraft. The theories and methods of detecting and characteristic analysis of nonlinear of dynimic system under random excitation are studied deeply in this paper, and using the random vibration test and take aluminum honeycomb sandwich, which has been widely used in aerocraft, as study object.In random test, if the input is white noise single, when the system is nonlinear system, the output is not white noise single anymore. Thus, the nonlinear detection of system become the nonlinear detection of output data. Using the higher 2order statistic spectrum and largest Lyapunov exponent to detect the nonlniear existence. To observe whether the bispectrum plot of output data is smooth to detect the nonlinear. If the possibility of the presence of chaotic behavior in the time-series data is explored, and the existence of nonlinear is proved.To deal with prolblems of detecting and characteristic analysis of nonlinear of dynimic system under random excitation. A method combining Fokker-PlancL-Ko1mogorov(FPK) transformation and equivalent principle method is used to caculate equivalent linear frequency response function (FRF) model of nonlinear systems containning nonlinear damping and nonlinear siffness, respectively. The shapes of equivalent linear FRF and Nyquist plots will change when the excitation level changed.and the rule is explored. The result can be the method of nonlinear detection and characteristic.Taking aluminum honeycomb sandwich board as subject, the project of random test is designed. The existence of nonlinear is detected by using FRF, the higher 2order statistic spectrum and the Lyapunov exponent methods. Owing to the chaonic phenomena of the data, and the state space reconstruction of the test data is done and Volterra adaptive filter is used to predict the test data. it is shown the test data could be accurately predicted.The FRF is gained, and thus the nonlinear characterise can be done by using acceleration data directly, thus the process of data tansformation is avoided. The nonlinear is characterised by using the classical FRF and the FRF expressed by acceleration of both input and output. The phenomena of natural frequency decreasing and other nonlinear phenomenon are explored. The applicability of the methods metined in this paper is proved.更多还原