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Detection method for quick estimation based on inherent frequency of damaged beam

A technology of natural frequency and detection method, applied in the field of detection based on the rapid estimation of the natural frequency of damaged beams, can solve the problem that the complexity is not easily accepted by enterprise engineers, and achieve the effect of overcoming the complexity of calculation

Active Publication Date: 2017-10-27
WENZHOU UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the complexity of the method itself is not easy for enterprise engineers to accept
Therefore, if the natural frequency of the damaged beam structure can be easily estimated, it will bring great convenience to the model-based detection of the damaged beam structure. However, there is no report on the detection method based on the rapid estimation of the natural frequency of the damaged beam.

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  • Detection method for quick estimation based on inherent frequency of damaged beam
  • Detection method for quick estimation based on inherent frequency of damaged beam
  • Detection method for quick estimation based on inherent frequency of damaged beam

Examples

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Embodiment example 1

[0084] Implementation case 1: In order to verify the effectiveness of the natural frequency estimation formula (13) of the damaged beam structure in the method of the present invention for single damage, the frequency estimation of the cantilever rectangular section beam structure with single damage in this implementation case and high-precision wavelet finite element calculation results Comparing the results with Figure 4 shown. The calculation parameters are as follows: beam length L=0.5m, elastic modulus E=2.1×10 11 N / m 2 , beam height h=0.02m, beam width b=0.012m, Poisson’s ratio μ=0.3, material density ρ=7860kg / m 3 . Figure 4 In addition to case 12(α 1 =0.6), 14(α 1 =0.6) and 16(α 1 =0.8), the third-order natural frequency of single-damage cantilever beam structural frequency estimation is in good agreement with the high-precision wavelet finite element calculation results. In an actual beam structure, if the relative degree of damage reaches 0.5, the structur...

Embodiment example 2

[0085] Implementation case 2: In order to verify the validity of the natural frequency estimation formula (13) of damaged beam structures in the method of the present invention to multiple damages, the frequency estimation of two damaged circular cross-section simply supported beam structures in this implementation case and high-precision wavelet finite element calculation results Comparing the results with Figure 5 shown. Calculation parameters are as follows: beam length L=0.85m, modulus of elasticity E=2.06×10 11 N / m 2 , circular section radius r 1 =0.01m, Poisson's ratio μ=0.3, material density ρ=7860kg / m 3 . The fourth-order natural frequencies estimated by the frequency estimation of two damaged circular cross-section simply supported beams are in good agreement with the high-precision wavelet finite element calculation results. Therefore, the natural frequency estimation formula (13) can be used to quickly estimate the frequency of multi-damage beam structure...

Embodiment example 3

[0086] Implementation case 3: In order to verify the effectiveness of the detection method based on the rapid estimation of the natural frequency of the damaged beam in this invention, this implementation case conducts detection based on the method of the invention for two actual damaged rectangular cross-section cantilever beam structures. The geometric parameters of the beam structure are as follows: beam length L=0.5m, beam height h=0.019m, beam width b=0.012m. Elastic modulus E=2.06×10 11 N / m 2 , Poisson's ratio μ=0.3, material density ρ=7860kg / m 3 . There are two damages on the beam structure, and the relative position of the damage is: β 1 =0.16, β 2 =0.76, the relative degree of damage is: α 1 =0.42, α 2 = 0.42. Hammer-excited modal experiments such as image 3 As shown, for the actual two cantilever beam structures with damaged rectangular section, the sampling frequency f s =5000Hz, the number of sampling points is 10000, while the beam structure is being str...

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Abstract

The invention relates to a detection method for the quick estimation based on the inherent frequency of a damaged beam. The method comprises the steps: proposing an estimation formula for estimating the inherent frequency of a structure through the inherent frequency of a good beam structure and a vibration model by employing the Rayleigh quotient during a single damage or multiple damages according to the theory of fracture mechanics; just employing the inherent frequency estimation formula to complete the building of a relation database of the inherent frequency of the damaged beam, the position of the single damage, the positions of the damages and the damage degree, and completing the direct problem solving based on a model; employing an exciting hammer shock excitation modal experiment to obtain the inherent frequency of an actual damaged beam structure as the input, solving the relation database through a back-propagating neural network method, and quantitatively detecting the damage position and degree of the beam structure. The method solves a problem that a conventional damaged beam structure detection method based on a model is complex in calculation of the inherent frequency of the damaged beam structure, quickly gives the relation database of the inherent frequency of the damaged beam, the position of the single damage, the positions of the damages and the damage degree, and brings great convenience to the detection of the damaged beam structure based on the model.

Description

technical field [0001] The invention belongs to the technical field of structural damage detection, and relates to a detection method based on rapid estimation of the natural frequency of a damaged beam. Background technique [0002] Beam is one of the basic components of various structures, and it is the most widely used flexural structure in engineering, such as beam bridges and beam-column systems of buildings, machine tool beams, crane beams, and crane girders. It is precisely because of the commonness and typicality of the beam 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, beam structures are faced with various damage failures, and damage is an inevitable physical defect that often occurs in beam structures. Research on damage detection method, to find an effective and fast method to judge whether ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01M5/00G06F17/50
CPCG01M5/0033G01M5/0066G06F30/20
Inventor 向家伟钟永腾周余庆任燕汤何胜
Owner WENZHOU UNIVERSITY
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