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Structural Modal Parameter Identification Method Based on Double Exponential Window Function Method

A technology for structural modal and parameter identification, which is applied in the processing of detected response signals, instruments, design optimization/simulation, etc. It can solve problems such as complex damping characteristics, and achieve the effects of less noise interference, elimination of errors, and strong robustness.

Inactive Publication Date: 2021-05-18
SOUTHWEST JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The damping characteristics of the actual structure are very complex, so far, a complete and effective damping model has not been established to describe the damping characteristics of the structure

Method used

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  • Structural Modal Parameter Identification Method Based on Double Exponential Window Function Method
  • Structural Modal Parameter Identification Method Based on Double Exponential Window Function Method
  • Structural Modal Parameter Identification Method Based on Double Exponential Window Function Method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment example 1

[0069] Implementation case 1: turbocharger impeller (30 blades) model

[0070] Taking a turbocharger with 30 impellers as an example, by solving the differential equation containing 10% blade detuning, the time-domain response signal of the speed of 30 blades when each blade is affected by the impact force is obtained. The signal duration is 1s, and the time The step size is Δt=1×10 -5 s; Table 1 shows the real natural frequency and damping ratio of the impeller by solving the characteristic equation composed of the impeller mass matrix and stiffness matrix.

[0071] Table 1 The real natural frequency and damping ratio of the impeller

[0072]

[0073] In order to verify the robustness of the identification method of this scheme, a 3dB signal-to-noise ratio is added to each group of signals, from figure 2 It can be seen that the signal is seriously polluted by noise at this time. Based on the force time history and velocity time history, a 30×30 structural admittance ma...

Embodiment example 2

[0075] Implementation Case 2: Floor Aluminum Profiles for High-speed Trains

[0076] Aluminum profile is a typical dynamic complex structure, and its finite element model is shown as Figure 4 As shown, 19 points are randomly selected in the upper and lower panels, such as Figure 5 shown. The hammer test is carried out for each measuring point separately, and the acceleration time-history signals of 19 measuring points are collected, the signal duration is 2s, and the time step is Δt=1.2207×10 -4 . Based on the force and acceleration time-history signals, a 19×19 admittance matrix can be obtained according to the steps of the scheme.

[0077] In order to illustrate that this scheme can flexibly select the attenuation rate, the attenuation rate b is given respectively 1 = 0.1dB and b 1 =-20dB exponential window function, the force and acceleration time-history signals are truncated and windowed, and obtained as Figure 6 The shown theoretical truncated windowed admittanc...

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Abstract

The invention discloses a structural modal parameter identification method based on a double-exponential window function method, which includes obtaining time-domain signals of several measuring points on the structure through a hammering method; Windowing is performed with the force time domain signal, the time length T is introduced to eliminate the error caused by the Fourier transform after the finite signal is truncated, and the theoretical truncated windowing admittance is constructed; the test acceleration and force time domain signals are used to construct the test truncated windowing admittance Nano; obtain the peak value of the test truncated windowed admittance averaged by all measuring points of the structure as the natural frequency of the structure; given the attenuation rate b 1 , Attenuation rate b 2 , take the real part of the theory / test truncation plus window admittance to get the equations about the attenuation rate, modal participation coefficient, natural frequency, and damping ratio, and use the nonlinear equation solver to solve the equations to get each measuring point at the natural frequency damping ratio. After that, the damping ratio of all measuring points is averaged as the damping ratio of the structure.

Description

technical field [0001] The invention relates to a structural mode parameter identification technology, in particular to a structural mode parameter identification method based on a double-exponential window function method. Background technique [0002] The damping of a structure is an important parameter to describe the energy dissipation of a structure. It is widely used in the engineering field and is generally obtained through experiments. The damping characteristics of the actual structure are very complex. So far, a complete and effective damping model has not been established to describe the damping characteristics of the structure. Most of the existing damping models are proposed under the premise of empirical assumptions. [0003] There are many identification methods for structural damping. At present, the experimental modal analysis method is widely used to identify the natural frequency and damping ratio. It is mainly divided into time domain analysis method and...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N29/04G01N29/44G06F30/23
CPCG01N29/045G01N29/4409G01N29/4472G01N2291/018G01N2291/0234
Inventor 圣小珍张淑敏杨世均陈宗平郎世伟史佳伟
Owner SOUTHWEST JIAOTONG UNIV