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A detection method based on rapid estimation of natural frequencies of damaged beams

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

Active Publication Date: 2019-09-13
WENZHOU UNIV
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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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  • A detection method based on rapid estimation of natural frequencies of damaged beams
  • A detection method based on rapid estimation of natural frequencies of damaged beams
  • A detection method based on rapid estimation of natural frequencies of damaged beams

Examples

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Effect test

Embodiment example 1

[0081] 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 single-damage cantilever rectangular section beam structure in this implementation case and high-precision wavelet finite element calculation results The comparison of the solution results is shown in the table below. 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 . In the table below except working condition 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 structure 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 d...

Embodiment example 2

[0085] Implementation case 2: In order to verify the effectiveness of the natural frequency estimation formula (13) of damaged beam structures in the method of the present invention for multiple damages, the frequency estimation of two simply supported beam structures with damaged circular sections in this implementation case and high-precision wavelet finite element calculation results The calculation results are compared as shown in the table below. The calculation parameters are as follows: beam length L=0.85m, elastic modulus 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 two damaged circular cross-section simply supported beam structures 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 bea...

Embodiment example 3

[0087] 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 of the present invention, this implementation case conducts detection based on the method of the present invention for two actual cantilever beam structures with damaged rectangular sections. 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 damaged cantilever beam structures with rectangular cross section, the sampling frequency f s =5000Hz, the number of sampling points is 10000, while the be...

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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] Beams are one of the basic components of various structures, and they are the most widely used flexural structures in engineering, such as beam-column systems of beam bridges and 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 rapid method to judge wh...

Claims

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Application Information

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Patent Type & Authority Patents(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 UNIV
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