Operation mode analysis experiment method and device based on pulse excitation

Abstract

An operation mode analysis experiment method based on pulse excitation comprises the following steps: (1) the endpoint of a beam is chosen as an excitation point, and a steel hammer is used to implement pulse excitation on the beam; (2) response signals generated by a reference point and a response point after pulse excitation are acquired; (3) band-pass filtering is performed on the acquired signals; (5) a cross-correlation function between the reference point and the response point is obtained, and a matrix equation set composed of data at different sampling moments of time of the cross-correlation function is constructed; (5) a coefficient matrix is solved by using the matrix equation set; (6) a system pole is identified, a least square error stabilization graph is established, and a modal shape is solved; and (7) if the modal assurance criterion value is poor, the value at a different sampling moment of time is selected, and the method returns to step (4) until the modal assurance criterion value is within a preset reasonable interval, and the modal parameters of the beam are obtained. The invention further provides an operation mode analysis experiment device based on pulse excitation. The time and the intensity of test can be reduced, and the students' learning effect can be improved.

Description

technical field [0001] The invention relates to the technical field of operation mode analysis, in particular to an operation mode analysis experiment method and device. Background technique [0002] In the teaching process of engineering testing technology, mechanical vibration and other courses, adding some modal analysis experiments can stimulate students' interest in learning, mobilize students' learning enthusiasm and initiative, cultivate students' innovative ability, and greatly improve the teaching effect. Through experiments, students can gain rich perceptual knowledge, deepen students' understanding of obscure physical concepts, theorems and laws, and reduce the difficulty of students encountering problems in the process of self-study; with the help of experiments, they can explain problems vividly, concretely and intuitively, and be able to Make abstract knowledge come alive quickly. [0003] The existing experimental modal analysis system generally consists of t...

AI Technical Summary

Problems solved by technology

The parameter identification methods in operational modal analysis can be divided into time domain, frequency domain and time-frequency domain identification methods, etc., mainly including time series method, random decrement method (random decrement, RD), environmental excitation method, random subspace method , Empirical mode decomposition (empirical mode decomposition, EMD), peak picking method, frequency domain decomposition method and continuous wavelet transform method, etc., the existing analysis methods are mostly based on the assumption that the excitation signal is zero-mean white noise, and each method is There are certain limitations, for example, it is difficult to determine the model order of the time series method; the natural excitation method requires long data samples and many average times; the determination of the model order of the stochastic subspace method is cumbersome, and when there are many measurement points, Hankel The order of the matrix is ​​very high, which is easy to cause the problem of matrix ill-conditioning; the disadvantage of the frequency domain method is that it requires high frequency resolution and long samples, and the structure is small damping; the time-frequency analysis method uses less response information and is a local identification method etc.

In order to improve the learning effect of students, it is necessary to carry out experimental teaching of operational modal analysis. However, there is no such experimental device at present, so the experimental method and device of operational modal analysis for teaching needs need to be studied urgently.

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