Modal parameter identification method for time-varying structures based on generalized subspace tracing
A technology of parameter identification and structural mode, which is applied in the testing of machine/structural components, CAD numerical modeling, special data processing applications, etc., can solve the problem of insufficient recognition accuracy of frequency and mode shape, low signal-to-noise ratio of vibration measurement data, The robustness of the method is not high, and the physical meaning is clear, the interference is reduced, and the robustness is good.
Active Publication Date: 2021-07-09
XIAN UNIV OF TECH
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Problems solved by technology
[0010] In order to solve the time-varying structure with large structure volume, complex operating environment, dense modes and large external interference in the existing technology, the constant modal parameters obtained by using the steady structural mode identification method are difficult to real-time Reflecting the time-varying nature of the structure under strong earthquake excitation, its vibration measurement data usually has a low signal-to-noise ratio, and the recognition accuracy of frequency and mode shape is insufficient, and the robustness of the method is not high. The present invention proposes a A New Time-Varying Modal Parameter Identification Method
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Embodiment 1
[0097] Example 1: Modal parameter identification of a four-degree-of-freedom time-varying structure under random excitation
[0098] use as figure 1 The spring-mass-damper system with 4 degrees of freedom shown is used as an example to prove the identification accuracy, robustness and calculation efficiency of the time-varying modal parameter identification algorithm proposed by the present invention.
[0099] Among them, the parameters of the system: m 1 =m 2 =m 3 =1.0kg,m 4 =0.9kg,k 3 =7000N / m,k 2 =k 4 =8000N / m,c 1 =c 2 =0.6N·s 2 / m,c 3 =c 4 =0.55N·s 2 / m, time-varying stiffness coefficient k 1 The changes are as follows,
[0100] Simulation working condition I: k 1 for a sudden change,
[0101]
[0102] Simulation working condition II: k 1 is a linear continuous change,
[0103] k 1 =6000+125t, (unit: N / m).
[0104] The initial state of the system is set to zero, and the basic environment stimulates a g (t) Simulated with Gaussian white noise excita...
Embodiment 2
[0164] Example 2: Identification of Modal Parameters of Pacoima Arch Dam in Different Earthquakes
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The present invention relates to a time-varying structural modal parameter identification method based on generalized subspace tracing. The steps are as follows: first, measure the vibration response of a structure with time-varying characteristics, construct a multi-dimensional time-delay vector according to the vibration response monitoring data, and calculate the vector Correlation function matrix, and use the eigenvalue decomposition to initialize the generalized subspace tracking algorithm; then, by introducing the forgetting factor, the correlation function matrix of the multi-dimensional time-delay The subspace tracking algorithm is used to update the orthogonal matrix Π(k) online, and finally, according to the updated orthogonal matrix Π(k), the discrete state space matrix and observation matrix at any time are calculated, and the discrete state space matrix is characterized The modal parameters such as modal frequency, damping ratio and mode shape of the structure are extracted through value analysis. The invention is applicable to the modal parameter identification of time-varying structures in various fields, and has the advantages of simple and convenient use, high calculation precision, strong robustness and high calculation efficiency.
Description
technical field [0001] The invention specifically relates to a time-varying structure modal parameter identification method based on generalized subspace tracing. Background technique [0002] Water conservancy projects, such as strong earthquake observation of dams, use sensors to measure the actual vibration response of structures under earthquake excitation. The identification of modal parameters of concrete arch dams based on strong earthquake observations can provide a basis for structural seismic analysis, health diagnosis, and post-earthquake structural damage assessment. The identification of modal parameters of concrete dams based on strong earthquake observations belongs to the research category of operational modal analysis (OMA) of structures. Modal parameters, such as natural frequency, damping ratio, modal mass, modal stiffness, and modal shape, have obvious physical meanings and can best reflect the real dynamic characteristics of the dam structure. [0003]...
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IPC IPC(8): G06F30/20G01M7/02G06F111/10
CPCG01M7/00G06F30/20G06F2111/10
Inventor 程琳仝飞李炎隆杨杰郑东健
Owner XIAN UNIV OF TECH