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Distributed optical fiber-protective layer-adhesive layer-matrix strain transfer calculation method

A technology of distributed optical fiber and calculation method, which is applied in the direction of using optical devices to transmit sensing components, using optical devices, converting sensor outputs, etc., can solve the problem of sensing optical fibers not being optical cables.

Active Publication Date: 2021-06-08
HARBIN INST OF TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in the process of applying distributed optical fiber sensing technology to the operation safety monitoring of actual civil engineering structures, in order to protect the sensing optical fiber from being damaged by changes in installation conditions and service environment, the surface of the optical fiber needs to be wrapped with a certain thickness of composite protective layer , that is, the sensing optical cable is formed; at the same time, the connection conditions and installation methods of the sensing optical cable and civil structures are often different due to different specific projects, resulting in the strain value of the sensing optical fiber test not being a true reflection of the actual strain of the base structure connected by the optical cable
In response to this problem, the present invention proposes a calculation method for distributed optical fiber-protective layer-adhesive layer-substrate strain transfer to solve the problem of accurate mapping between the test value of the distributed sensing optical cable and the actual strain of the substrate structure connected to the optical cable

Method used

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  • Distributed optical fiber-protective layer-adhesive layer-matrix strain transfer calculation method
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  • Distributed optical fiber-protective layer-adhesive layer-matrix strain transfer calculation method

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specific Embodiment approach 1

[0022] Specific implementation mode one: as figure 1 As shown, this embodiment discloses a calculation method for distributed optical fiber-protective layer-adhesive layer-substrate strain transfer, the method includes the following steps:

[0023] Step 1: Determine the stiffness index of the optical fiber composite protective layer according to the cross-sectional parameters of the distributed sensing optical cable, construct the shear relationship model between the core optical fiber and the composite protective layer, and calculate the strain transfer rate of the core optical fiber-composite protective layer;

[0024] Step 2: According to the field layout conditions of the distributed sensing optical cable, determine the thickness and shear modulus of the adhesive layer of the distributed sensing optical cable, and calculate the composite protective layer-adhesive layer-substrate strain transfer rate based on the shear lag theory;

[0025] Step 3: According to the field lay...

specific Embodiment approach 2

[0027] Embodiment 2: This embodiment is a further description of Embodiment 1. The calculation method of the core optical fiber-composite protective layer strain transfer rate described in step 1 is:

[0028] Step 11: taking the rigid layer (i.e. steel strand) in the composite protective layer as the boundary, divide the composite protective layer into inner protective layer-rigid layer-outer protective layer structure, determine the cross-sectional size and material parameters of each layer layer by layer, The shear relationship model between the core optical fiber and the composite protective layer is constructed as shown in formula (1),

[0029]

[0030] where r f is the radial distance from the core fiber axis to the core fiber-inner protective layer interface, r i is the radial distance from the core fiber axis to the inner protective layer-rigid layer interface, τ f is the shear stress at the core fiber-inner protective layer interface, ε f is the normal strain of ...

specific Embodiment approach 3

[0034] Specific embodiment three: This embodiment is a further description of specific embodiment one. The calculation method of the composite protective layer-adhesive layer-substrate strain transfer rate described in step two is:

[0035] Step 21: Determine the size and material properties of the adhesive layer of the sensing optical cable, and construct a composite protective layer-adhesive layer-substrate strain transfer model based on the shear lag theory according to formula (3),

[0036]

[0037] where r s is the radial distance from the core fiber axis to the rigid layer-outer protective layer interface, r o is the radial distance from the axis of the core fiber to the interface of the outer protective layer-paste layer, r a is the radial distance from the axis of the core fiber to the adhesive layer-substrate interface, τ s is the shear stress at the interface between the rigid layer and the outer protective layer, ε s is the normal strain of the rigid layer, τ ...

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Abstract

The invention discloses a distributed optical fiber-protective layer-adhesive layer-matrix strain transfer calculation method, and belongs to the field of civil engineering structure operation safety intelligent monitoring. The method comprises steps: according to section parameters of the adopted distributed sensing optical cable, constructing a shearing relation model of the core optical fiber and the composite protection layer, and then calculating the strain transmissibility of the core optical fiber-composite protection layer; calculating a composite protection layer-adhesive layer-matrix strain transmissibility based on the shear lag theory according to the on-site layout condition of the distributed sensing optical cable; establishing an optical fiber-composite protection layer-adhesive layer-matrix numerical model of distributed optical fiber sensing, and obtaining a corrected strain transmissibility of the optical fiber-composite protection layer-adhesive layer-matrix; and summarizing and analyzing the statistical characteristics of the parameter indexes of the adhesive layer of the optical cable to obtain an optical fiber-composite protection layer-adhesive layer-matrix strain transmission result considering the influence of the construction and installation factors of the optical cable. The problem of accurate mapping of the sensing optical cable test value and the actual strain of the base body structure connected with the optical cable is solved.

Description

technical field [0001] The invention belongs to the field of intelligent monitoring of civil engineering structure operation safety, and in particular relates to a calculation method for distributed optical fiber-protective layer-adhesive layer-substrate strain transfer. Background technique [0002] Large-scale civil structures have a long service life, and are inevitably affected by factors such as environmental corrosion, material aging, and long-term effects of loads during their service period, making their working capacity decline. Once these structures lose their ability to work, it will bring huge losses and the consequences will be unimaginable. Therefore, it is extremely important to conduct long-term monitoring of large civil engineering structures during their service period, diagnose and find problems in time, and eliminate potential hidden dangers. Since civil engineering structures are often huge in size and have many degrees of freedom, an effective sensing t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/16G01D5/353
CPCG01B11/16G01D5/35383
Inventor 刘洋徐乾恩李虎门燕青黄永亮
Owner HARBIN INST OF TECH