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Structural damage detection method based on nonlinear output frequency response function

A technique for outputting frequency and response function, which is used in the processing of detected response signals, analysis of solids using sonic/ultrasonic/infrasonic waves, etc.

Inactive Publication Date: 2012-06-27
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the multidimensional nature of the generalized frequency response function, it encounters great difficulties in practical applications

Method used

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  • Structural damage detection method based on nonlinear output frequency response function
  • Structural damage detection method based on nonlinear output frequency response function
  • Structural damage detection method based on nonlinear output frequency response function

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0059] The method of the present invention is used to detect the damage of the bridge structure model. In this embodiment, the damage of the bridge structure is caused by loosening the bolts connecting the bridge structure to simulate the loosening of the daily bridge structure. figure 2 The schematic diagram of the model of the bridge structure is shown. In the figure, 1 is the measurement response point of the acceleration sensor, 2 is the excitation point of the white noise signal, 3 is the connecting bolt of the bridge model structure, and 4 is the 2mm butt joint gap of the bridge model structure.

[0060] image 3 Shown is the experimental detection flow chart of this embodiment. Use a white noise source to generate a broadband white noise signal, and use a low-pass filter to filter it to make its energy more concentrated; because the signal energy generated by the white noise source is limited, a linear power amplifier is required to amplify it. And use the white noise...

Embodiment 2

[0091] The method of the invention is used for damage detection of the aluminum plate, and the damage is simulated by processing seams and round holes. Figure 5(A) ~ Figure 5(C) Shown are the schematic diagrams of the structure of the aluminum plate in three different states, where Figure 5(A) shows the aluminum plate without damage, 1 is the measurement response point, and 2 is the excitation point. Figure 5(B) is an aluminum plate with a circular hole 5 with a diameter of 2mm, and Figure 5(C) is an aluminum plate with a 10×0.4mm slit 6, and all other experimental conditions are the same.

[0092] Using the similar damage detection steps in Embodiment 1, the nonlinear output frequency response function of the structure in different states and related indexes of the nonlinear output frequency response function can be obtained, as shown in Table 4 and Table 5 respectively.

[0093] Table 4

[0094]

[0095] table 5

[0096]

example 2

[0097] The experimental results of Example 2 also prove that it is feasible to judge whether the system is damaged by comparing the indicators related to the nonlinear output frequency response function of the system in two different states.

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Abstract

The invention provides a structural damage detection method based on a nonlinear output frequency response function. Damage detection is performed on an engineering structure by adopting a NARMAX:nonlinear auto- regressive moving average with exogenous input) and the nonlinear output frequency response function (NOFRF) analysis method. The structural damage detection method based on the NOFRF mainly comprises the following three steps: firstly, identifying the NARMAX model of a system by utilizing experimental data, and obtaining a nonlinear auto-regressive exogenous model (NARX model) of the system according to the obtained NARMAX model; secondly, according to the obtained NARX model, calculating the NOFRF of the system and indexes related with the NOFRF; and finally, judging whether the system is damaged or not through comparing the indexes related with the NOFRF of the system under different states. The damage detection method provided by the invention is simple in operation and convenient in calculation. Another effective path is provided for structural damage detection.

Description

technical field [0001] The invention proposes a new technology for damage detection of engineering structures based on NARMAX model (nonlinear autoregressive moving average model with external input) and NOFRF (nonlinear output frequency response function) analysis method, which is used in the field of health monitoring. Background technique [0002] Under the combined action of environmental erosion, material aging, long-term effects of loads, fatigue effects, and catastrophic effects, engineering structures will accumulate damage to the structural system, resulting in damage to the structure or degradation of performance. In extreme cases, catastrophic damage may occur. accidents, resulting in huge economic losses and social impact. Therefore, it is of great significance to study the damage detection methods of engineering structures to prevent the occurrence of serious accidents and reduce the loss of life and property. Based on this consideration, researchers have done ...

Claims

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Application Information

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IPC IPC(8): G01N29/12G01N29/44
Inventor 彭志科
Owner SHANGHAI JIAO TONG UNIV
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