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本文在多输入——多输出实验模态参数识别技术离散统一模型的基础上,介绍了几种得到广泛应用的多输入——多输出实验模态参数时域识别技术,如直接参数模型识别法,Polyreference 识别法,Ibrahim 时域法和特征系统实现算法(ERA),并将这几种算法统一在一个基本的数学模型—离散的统一模型上,指出了这几种识别方法相互之间的联系。 相似文献
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对于具有非比例阻尼的多自由度线性振动系统的研究需要用到复模态理论.本文根据复模态有关理论,分析了复模态传递函数和频响函数的特性,定义了模态固有频率和模态阻尼比,导出了频响函数与复模态参数的解析关系式。在此基础上,介绍了由频响数据识别复模态参数的导纳圆拟合法.为了进一步提高模态识别精度,还论述了由加速度频响数据识别复模态参数的两种迭代方法:分步迭代法和整体迭代法.文中还以某航天器刚性太阳电池板模态试验为例,介绍了利用导纳圆拟合法联机模态识别枝术,给出了两种方法的模态识别结果,并进行了比较. 相似文献
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本研究主要研究混凝土徐变特性的分数阶模型拟合及其多参数识别问题。在模型方面,提出利用修正的分数阶Maxwell模型和分数阶Poynting-Thomson模型两种模型模拟混凝土的徐变实验数据,并将结果进行对比,通过数据拟合和误差分析验证两种模型的有效性。在多参数识别方面,分别采用贝叶斯算法和布谷鸟搜索算法两种算法识别两个模型中的多个参数。研究表明:修正的分数阶Maxwell模型和分数阶Poynting-Thomson模型在刻画混凝土徐变特性中均是有效的;贝叶斯算法和布谷鸟搜索算法在分数阶模型的多参数估计问题中均是可行的,但布谷鸟算法搜索速度更快、误差更小、效率更高,在分数阶模型的多参数识别问题中性能更优。 相似文献
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蚁群算法求解二维拉压不同模量反问题 总被引:2,自引:2,他引:0
利用光滑函数技术对二维拉压不同模量本构关系进行光滑化处理,采用初应力方法求解二维拉压不同模量正问题的有限元方程。在此基础上,建立了基于连续域蚁群算法的二维拉压不同模量反问题的数值求解模型,考虑了区域非均质的影响,实现了对拉压弹性模量和泊松比的单一/组合识别。通过两个数值算例,对所提算法进行了数值验证,分别探讨了蚁群算法相关参数、测点分布和数据噪音等对识别结果的影响。数值验证表明,所提算法可有效地求解二维拉压不同模量反问题,并具有较好的计算精度。 相似文献
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基于实验模态参数的结构多层结合部参数识别 总被引:1,自引:0,他引:1
本文从一般情况出发,提出了一种利用结构实验模态参数与子结构有限元模型,识别结构多层结合部刚度与阻尼参数的方法。当结合部模态向量分别为可测,部分可测或不可测时,给出了相应的识别算法,特别地,当结合部模态向量为可测时,其识别算法无任何矩阵求逆运算。算例表明,本文方法具有满意的识别精度。 相似文献
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本文利用状态空间方程给出一般粘性阻尼线性振动系统的线性高阶微分多项式模型,及其所对应的离散差分模型.这个模型描述了系统多输入激励信号和多输出响应信号之间的关系.近十年来发展起来的多输入—多输出实验模态参数识别都是建立在这个模型之上的,在这个意义上,我们称之为多输入—多输出实验模态参数识别技术的统一数学模型.当考虑到测量频段外模态和测量数据中噪声的影响时,本文也给出了相应的统一数学模型. 相似文献
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In this paper, the on-orbit identification of modal parameters for a spacecraft is investigated. Firstly, the cou-pled dynamic equation of the system is established with the Lagrange method and the stochastic state-space model of the system is obtained. Then, the covariance-driven stochas-tic subspace identification (SSI-COV) algorithm is adopted to identify the modal parameters of the system. In this algo-rithm, it just needs the covariance of output data of the system under ambient excitation to construct a Toeplitz matrix, thus the system matrices are obtained by the singular value decom-position on the Toeplitz matrix and the modal parameters of the system can be found from the system matrices. Finally, numerical simulations are carried out to demonstrate the validity of the SSI-COV algorithm. Simulation results indi-cate that the SSI-COV algorithm is effective in identifying the modal parameters of the spacecraft only using the output data of the system under ambient excitation. 相似文献
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Ralph Quan 《Experimental Mechanics》1995,35(1):42-48
Reaction-mass devices are to be used in a dual role: first for the purpose of system identification, and second for the purpose of vibration suppression. Unlike ground-based shakers, reaction-mass devices have a position constraint which must be maintained. A two-part system identification procedure is described which maintains this constraint. In the first part, a new algorithm is used to obtain the impulse response from input-output data. The second part uses the eigensystem realization algorithm to determine linear matrix models of the structure and of the reaction-mass device. This procedure is demonstrated on a small experimental structure. The usefulness of the model for the design of a vibration suppression controller is also demonstrated. 相似文献
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The modal coupling behavior of a compressed, imperfect plate is examined as a six degree of freedom structural system. A direct variational solution procedure is developed by the use of the functional for the total potential energy of the system. The non-linear algebraic equations generated are solved by use of a continued perturbation technique. The segmented deflection history is then developed for a variety of imperfection compositions and aspect ratios. 相似文献
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采用流固耦合方法对跨音速颤振进行了数值模拟。流体方面在非结构网格上用有限体积方法求解了Euler方程;结构方面则求解了后掠机翼典型剖面的结构模态方程。时间推进采用双时间步长:对每一真实时间步,都通过基于聚合多重网格方法的伪时间步推进,对流体和结构方程交替迭代.得到一个稳态的流固耦合的解。文章最后给出了NACA64A010翼型剖面的跨音速颤振边界.与相关文献的计算结果符合良好。 相似文献
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基于控制响应的时变系统模态参数辨识的改进子空间方法 总被引:1,自引:1,他引:0
提出了一种基于系统控制信号激发的响应数据来辨识时变系统模态参数的改进子空间方法。该方法以系统控制响应信号建立系统的状态空间输出方程并构造了一个广义Hankel矩阵,通过对该矩阵做奇异值分解(SVD),用广义能观阵的估计代替输出矩阵,然后利用奇异值矩阵的正交性,有效地降低了噪声敏感性和计算量,从而容易地辨识出等效状态下的系统矩阵,最后采用转换矩阵辨识出时变系统的模态参数。通过理论分析、仿真和实验,讨论了不同信噪比对辨识结果的影响,验证了该方法的有效性。 相似文献
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A nonparametric structural damage detection methodology based on neural networks method is presented for health monitoring
of structure-unknown systems. In this approach appropriate neural networks are trained by use of the modal test data from
a ‘healthy’ structure. The trained networks which are subsequently fed with vibration measurements from the same structure
in different stages have the capability of recognizing the location and the content of structural damage and thereby can monitor
the health of the structure. A modified back-propagation neural network is proposed to solve the two practical problems encountered
by the traditional back-propagation method, i.e., slow learning progress and convergence to a false local minimum. Various
training algorithms, types of the input layer and numbers of the nodes in the input layer are considered. Numerical example
results from a 5-degree-of-freedom spring-mass structure and analyses on the experimental data of an actual 5-storey-steel-frame
demonstrate that neural-networks-based method is a robust procedure and a practical tool for the detection of structural damage,
and that the modified back-propagation algorithm could improve the computational efficiency as well as the accuracy of detection
Project supported by the National Natural Science Foundation of China (No. 59908003) and the Natural Science Foundation of
Hubei Province (No. 99J035). 相似文献
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Krzysztof Mendrok Piotr Kurowski 《Archive of Applied Mechanics (Ingenieur Archiv)》2013,83(4):509-519
In the paper, the procedure for the estimation of modal filter coefficients from output-only data is presented. The basic concept of the procedure consists in frequency response functions synthesis based on the knowledge of an operational modal model. A method of operational mode shapes scaling is described. The method is then compared with the classical modal filter and with modal filtration of responses spectra, which is sometimes used as a solution for modal filtration based on the output-only data. Each solution is applied to load identification and damage detection. The study shows the method verification on data obtained from laboratory experiment. 相似文献
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GPS/捷联惯性组合导航系统的一种半实时算法 总被引:3,自引:0,他引:3
本文讨论了GPS/捷联惯性组合导航系统的原理和特点,针对其理论仿真和工程实现中的衔接问题,提出了一种半实时算法。该算法既继承了理论仿真方便、直接的优点;又充分利用了实测数据。系统调试成功后,可以直接将全套软件转换到导航计算机中。文中给出了半实时算法的原理和方案,讨论了组合卡尔曼滤波器的实现和GPS仿真器、航迹仿真器、惯性器件等的设置。最后给出了有关结论。 相似文献
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运行模态参数识别是一种只利用响应数据进行模态分析的方法。环境激励条件下获得的识别结果会存在随机不确定性,这种不确定程度可以通过模态参数的统计特性进行描述评价。以运行模态分析中的频域空间域分解方法(FSDD)为研究对象,通过对整个模态识别算法进行摄动分析,确定出模态参数对测量误差的灵敏度,实现了模态参数方差的计算。计算过程分为四步:第一步,响应信号功率谱矩阵中噪声方差的估计;第二步,增强功率谱方差的计算;第三步,极点协方差的计算;第四步,模态参数方差的计算。最后通过一个4自由度仿真算例与张家港桥梁实测算例对所给出的方法进行了验证与应用。 相似文献