共查询到19条相似文献,搜索用时 62 毫秒
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基于环境激励的模态参数识别方法在桥梁健康监测领域应用广泛,所识别桥梁的模态参数的变化常用来进行损伤识别。然而在模态参数识别过程中,移动车辆本身具有的质量属性被忽视,仅被当作为环境激励的一部分。桥梁损伤导致的模态参数变化将被移动车辆所引起的变化掩盖,影响后续损伤识别的效果。以随机子空间法为例,研究环境激励下的模态参数识别方法识别的桥梁模态参数的变异情况,并对比桥梁局部损伤导致的桥梁模态参数的变化量,结果表明局部损伤和移动车辆都会造成频率减小和振型改变,因此在实际模态测试中需要考虑移动车辆作用并剔除其影响。 相似文献
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本文根据国内外最新文献,对目前环境激励线性结构模态参数的辨识方法如频域分解法、ARMA模型法、NExT法、随机子空间法、时频分析方法和基于相关函数分解法等进行了评述,讨论了各方法在理论上和实际应用中存在的问题,对环境激励的模态参数识别方法的发展方向和趋势进行了探讨. 相似文献
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非稳态环境激励下线性结构的模态参数辨识 总被引:14,自引:2,他引:12
假定任意随机激励信号由白噪声与非白噪声信号组成,由此导出线性结构响应之间的相关函数由两部分组成,一部分与脉冲响应具有相同的数学形式,另一部分为其它形式,利用模态分解法的基本原理,把相关函数分解为各个模态函数的叠加与余项之和,这样,第一部分信号已经分解为不同的模态函数,第二部分中的周期信号也变成了模态函数,这就把非稳态环境激励下多自由度线性结构系统的模态参数辨识问题转化为类似于已知各个单自由度系统的脉冲响应进行模态参数辨识问题,理论和模拟实验表明,本文成功地利用模态分解法进行非稳态环境激励下多自由度线性结构系统的模态参数辨识,其主要优点是,无论是白噪声激励,稳态随机激励还是非稳态随机激励,仅根据结构的响应不仅能辨识线性结构的模态参数,而且能有效地识别出环境激励中的周期成分。 相似文献
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从响应信号辨识斜拉桥模型的模态参数 总被引:4,自引:8,他引:4
针对斜拉桥模型在平稳随机激励下的模态参数辨识问题,研究了提高子空间方法参数辨识精度和可信度的有效途径。在矩阵奇异值分解的基础上,文中使用信号特征分量的能量指标来估计模型阶次,同时给出一种特征频率随拟合数据变化的稳定图。在虚假特征显示能力以及降低数值运算量等方面,这种形式的稳定图与能量指标的结合具有正更大的优越性。在斜拉桥模型的模态参数辨识中,物理模态和寄生模态得到了很好的分离,而且斜拉桥模型在分析频带内的物理模态被全部识别出来。辨识结果的比较说明了给出的辨识方法是有效的。 相似文献
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本文讨论全相干多点随机激励下频响函数的估计、相干函数计算及模态参数识别;设计了用单点激振模态分析设备获取多点激振下的频响函数和模态参数的方法;分析了激振力的非比例误差和非全相干误差对分析精度的影响及补偿措施;并提出了一个输入、输出噪声同时存在情况下提高频响函数估计精度的计算公式;用全相干多点激振的观点分析讨论了机床的相对式激振试验并作出了有关结论,最后对以上理论进行了工程应用考核,取得较好的效果. 相似文献
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The response of the Van der Pol oscillator subjected to combined harmonic and random excitations is investigated by a technique combining two excellent methods, namely the stochastic averaging method and the equivalent linearization method. The original equation is averaged by the stochastic averaging method at first. Then the resulting nonlinear averaged equations are linearized by the equivalent linearization method so that the equations obtained can be solved exactly by the technique of auxiliary function. The mean square response of the Van der Pol oscillator is computed algebraically and compared to the ones obtained by numerical simulation and by technique combining methods of stochastic averaging and equivalent non-linearization. The results show that the proposed technique gives a good prediction on mean square responses of the Van der Pol oscillator. In addition, the proposed technique can be applied to other nonlinear systems for it does not require any special conditions, and it can be improved by advanced optimization criteria of the equivalent linearization method. 相似文献
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Analytical and experimental methods have been used to investigate fatigue failures in the weatherhood protecting the air inlet to an offshore gas turbine power generation unit. A simple method for modelling transverse vibration of the leading edge is described, and the results are compared with experimental measurements made on a prototype installation. Calculation of the stresses induced at the critical locations, where cracking has been observed, suggests the failure should be attributed to aerodynamic excitation of the leading edge. 相似文献
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Bal K Agrawal S Agrawal P S Yadav S Kumar J S Negi Namrata Varshney 《Bulletin of Materials Science》1991,14(4):967-971
In the series of the layered highT
c
superconductors (A)1,2 B2Ca
n−1Cu
n
O2n+3,4 (A=Tl or Bi;B=Ba or Sr), withn=number of consecutive Cu-O layers, the electron energy states of some of the Tl-based systems have been investigated. The
electron and phonon dispersion curves have been obtained. The electronic states near the Fermi level are dominated by the
hybridized Cu(d) and the O(p) orbitals. The dispersion curves are highly two-dimensional with very small dispersion alongc-axis. The number of bands is enhanced with increase in the number of the consecutive Cu-O planes (n). The present results agree with those obtained earlier for other superconducting phases. The phonons are overall dominated
by the vibrations of the light mass oxygen atom modes both lying in or outside the Cu-O planes. The low-frequency phonons
involve the motions of the heavier Tl, Ba atoms etc. 相似文献
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Recursive formulas in terms of statistics of the response of linear systems with time delay under normal white noise input are developed. Two alternative methods are presented, in order to capture the time delay effects. The first is given in an approximate solution obtained by expanding the control force in a Taylor series. The second, available for the stationary solution (if it exists) gets the variance of the controlled system, with time delay in an analytical form. The efficacy loss in terms of statistics of the response is discussed in detail. 相似文献