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Plate damage fast detecting method

A detection method, a fast technology, applied in the direction of measuring device, vibration test, machine/structural component test, etc., can solve the problems of missed detection and false alarm, and achieve the effect of speeding up the detection speed

Active Publication Date: 2017-05-31
WENZHOU UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Especially for the structural damage of transparent damage thin plates, it is necessary to detect whether there is damage and evaluate the three parameters of the damage (orientation, damage center position, and damage length). The existing vibration-based structural health detection methods are very likely to cause missed detection and false alarm
Therefore, if a method can be proposed to pre-evaluate whether there is damage, as well as the damage orientation and damage center, and then perform a simple estimation of the natural frequency of the transparent damaged thin plate structure, it will bring great benefits to the detection of transparent damaged thin plate structures based on vibration. Great convenience, there is no report about the research in this area

Method used

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Examples

Experimental program
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Effect test

Embodiment example 1

[0089] Implementation case 1: In order to verify the effectiveness of the natural frequency estimation formula (6) of the permeable damage thin plate structure in the method of the present invention for single damage, this implementation case is a permeable single damage four-sided simply supported thin plate structure, calculation parameters: l x = 150mm, l y =100mm, h=5mm, E=1.923×10 11 N / m 2 , μ=0.33, ρ=7810kg / m 3 . Figure 6 According to different relative damage center positions α c1 =x c1 / l x , β c1 =y c1 / l y , damage orientation relative lesion length γ 1 , eight damage cases are given.

[0090] Figure 7 Shown are the natural frequency estimation and finite element calculation solution results Compare. right Figure 6 Given eight working conditions, the maximum errors of the sixth order natural frequency are 0.146%, 0.293%, 0.063%, 0.121%, 0.079%, 0.036%, respectively. It can be seen that the results are in good agreement, indicating the effective...

Embodiment example 2

[0091] Implementation case 2: In order to verify the effectiveness of the natural frequency estimation formula (6) of the permeable damaged thin-plate structure in the method of the present invention to multiple damages, this implementation case is a permeable three-damaged four-sided simply supported thin-plate structure, and the calculation parameters are: l x = 150mm, l y =100mm, h=5mm, E=1.923×10 11 N / m 2 , μ=0.33, ρ=7810kg / m3 . Figure 8 According to different relative damage center positions α ci =x ci / l x , β ci =y ci / l y , damage orientation relative lesion length γ i , five damage cases are given.

[0092] Figure 9 Shown are the natural frequency estimation and finite element calculation solution results Compare. right Figure 8 Given the five working conditions, the maximum errors of the sixth-order natural frequency are 0.105%, 0.316%, 0.428%, 0.262%, 0.079%, and 0.038%, respectively. It can be seen that the results are in good agreement, indic...

Embodiment example 3

[0093] Implementation case 3: In order to verify the effectiveness of the detection method of the present invention, this implementation case detects the actual existence of two transparent damaged thin plate structures. Such as Figure 4 As shown, the geometric parameters are as follows: l x =1000mm, l y =1000mm, h=20mm, E=2.06×10 11 N / m 2 , μ=0.3, ρ=7860kg / m 3 . There are two damages on the thin plate structure: the position of the damage center (x c1 =0.1,y c1 =0.1) and (x c2 =0.6,y c2 =0.7), damage location and Lesion Relative Length γ 1 = 0.1 and γ 2 = 0.2.

[0094] Hammer-excited modal experiments such as image 3 As shown, for the actual two transparent damage thin plate structures, the sampling frequency f s = 4000Hz, the number of sampling points is 10000, and the first mode shape and the first three natural frequencies of the actual transparent damaged thin plate structure are obtained by using the hammer excitation mode experiment. The experimental...

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Abstract

The invention relates to a plate damage fast detecting method. The method comprises the steps that any step of vibration mode and front q-step inherent frequency are firstly acquired; whether a transparent damage thin-slab structure is damaged or not is evaluated, and the damage orientation and the damage center position are obtained; the estimation formula of the inherent frequency when the structure has single and multiple transparent damage is obtained; then a relation database between the front q-step inherent frequency of the structure and single and multiple damage lengths is set up; the damage length of the transparent damage thin-slab structure is quantitatively detected. On the one hand, the problem that calculation of the inherent frequency of an existing transparent damage thin-slab structure is complex is solved, the relation database between the inherent frequency and multiple damage lengths of the transparent damage thin-slab structure is fast given, and great convenience is brought to damage plate structure detection based on a model; on the other hand, a provided section Daubechies certain step vibration mode wavelet decomposition method can be used for evaluating whether the damage exists or not in advance and determining the damage orientation and the damage center position, and the detecting speed is further increased.

Description

technical field [0001] The invention belongs to the technical field of structural damage detection and relates to a rapid detection method for plate damage. Background technique [0002] The plate is one of the basic components of various structures, and it is the most widely used bending structure in engineering, such as beam bridge pavement, thin plate members of ships, containers, automobile or railway locomotive cars, pipelines, and various mechanical equipment bottom plates etc. Carriers. It is precisely because of the commonness and typicality of the plate structure in engineering that its operation safety has become an important work content in daily maintenance. In contemporary industrial production, due to the complex working environment and super-strength cyclic work, the plate structure is faced with various damage failures, and damage is an inevitable physical defect often produced by the plate structure. Research on damage detection method, to find an effectiv...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01M7/02
CPCG01M7/00
Inventor 向家伟钟永腾周余庆任燕汤何胜
Owner WENZHOU UNIVERSITY
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