CN1758017A - Optical fiber grating sensor enbedded in highway and its packaging method - Google Patents

Abstract

An optical-fiber raster sensor buried in highway is composed of optical-fiber Bragg raster sensor the extending line of Bragg raster, and protecting sleeve tube. Its packaging method includes such steps as passing said extending line in the protecting sleeve tube, fusion connection between said extending line and raster, packaging by use of glass fiber cloth and unsaturated polyester resin, and solidifying. It can be used to measure the strain of concrete.

Description

Imbed fiber-optic grating sensor and method for packing thereof in the highway

(1), affiliated field

What the present invention relates to is a kind of sensor, the present invention also relates to a kind of method for making of sensor, specifically a kind of fiber-optic grating sensor and method for packing thereof that is used for highway communication field measurement surface deformation.

(2), background technology

The health condition of highway pavement is smooth and easy most important to communications and transportation, has only the qualified flatness in the road surface of maintenance, and vehicle could pass through according to certain speed.Therefore, use embedded-type sensor to measure the distortion situation on road surface, the health condition on road surface is provided in time, when distortion reaches extreme value, keep in repair at once, transport by road is all had positive meaning.

Traditional metal strain plate only is suitable for the surface and pastes as sensor, can't carry out the flush type operation.Fiber grating is imbedded and is made into intellectual material in the compound substance, for embedded-type sensor provides possibility.Fiber grating is applied in the civil structure, and work under bad environment is directly imbedded optical fiber and can't be survived at all.Fiber-optic grating sensor is used for civil engineering work, and primary problem is the encapsulation that solves sensor, and the protection sensor can both normally be worked under any condition.

(3), summary of the invention

The object of the present invention is to provide a kind of suitable encapsulation, make the later sensor of encapsulation can imbed the concrete road surface, be used to measure surface deformation.

The object of the present invention is achieved like this: it comprises fiber Bragg grating sensor, and the glass mat encapsulation is arranged outside fiber Bragg grating sensor, is with protective casing on the extended line of Fiber Bragg Grating FBG.

Product of the present invention is to adopt such method to make: select for use Fiber Bragg Grating FBG as sensor; the extended line of Fiber Bragg Grating FBG is penetrated in the protective casing; make the extended line of Fiber Bragg Grating FBG be arranged in protective casing; then Fiber Bragg Grating FBG and extended line are welded together; encapsulate at last; concrete packaging technology is: glass fabric is cut into rectangle, and totally 6, the prescription below unsaturated polyester resin adopts:

The composition weight portion

100 parts of 191 unsaturated polyester resins

2 parts of peroxidating methohexitones

Cobalt naphthenate 1-4 part

At glass upper berth layer of glass cloth, smear one deck unsaturated polyester resin, repave layer of glass cloth after being coated with evenly, when being taped against the 3rd layer, place fiber Bragg grating sensor, continue the lay glass fabric then, up to layer 6, solidify after 1 hour, to week to cutting finishing, after half an hour, scoop up from glass.

Sensor of the present invention uses Fiber Bragg Grating FBG.Fiber Bragg Grating FBG is that a kind of wavelength is selected reverberator, and the mathematic(al) representation of the centre wavelength that it reflects is:

λ _B＝2n _effΛ

Its differential form can be expressed as:

$\frac{\mathrm{\Δ}{\mathrm{\λ}}_B}{{\mathrm{\λ}}_B}=\frac{n_{\mathrm{eff}}}{n_{\mathrm{eff}}}+\frac{\mathrm{\Δ\Λ}}{\mathrm{\Λ}}$

Λ is the cycle of grating in the formula, and n is the effective refractive index of fibre core.As can be seen from the above equation, every physical quantity that can cause variation of fiber grating effective refractive index or grating cycle to change all can cause the variation of bragg wavelength.When Fiber Bragg Grating FBG is subjected to external force effect generation strain, the grating cycle will change, and effective refractive index is because elasto-optical effect also can change simultaneously, and the change amount of effective refractive index is:

$\mathrm{\Δ}{n}_{\mathrm{eff}}=-\frac{{n_{\mathrm{eff}}}^3[P_{12}-\mathrm{\υ}(P_{11}+P_{12})}{2}{\mathrm{\ϵ}}_x$

So have:

$\frac{\mathrm{\Δ}{n}_{\mathrm{eff}}}{n_{\mathrm{eff}}}=-\frac{{n_{\mathrm{eff}}}^2}{2}[P_{12}-\mathrm{\υ}(P_{11}+P_{12})]{\mathrm{\ϵ}}_x$

P in the formula _Li(i=1,2) are the elasto-optical coefficient of single-mode fiber, and v is the Poisson ratio of fiber optic materials, ε _xBe the axial strain that optical fiber produces, Fiber Bragg Grating FBG is the grating of uniform period, so have:

${\mathrm{\ϵ}}_x=\frac{\mathrm{\Δ\Λ}}{\mathrm{\Λ}}$

So when fiber grating produced strain, the total bragg wavelength that is caused by two kinds of effects was changed to relatively:

$\frac{\mathrm{\Δ}{\mathrm{\λ}}_B}{{\mathrm{\λ}}_B}=\{1-\frac{{n_{\mathrm{eff}}}^2}{2}[P_{12}-\mathrm{\υ}(P_{11}+P_{12})\left]\right\}{\mathrm{\ϵ}}_x$

Note

$P_e=\frac{{n_{\mathrm{eff}}}^2}{2}[P_{12}-\mathrm{\υ}(P_{11}+P_{12})]$

P _eThe effective elasto-optical coefficient that is called optical fiber, for silica fibre, P _e≈ 0.22, so have:

$\frac{\mathrm{\Δ}{\mathrm{\λ}}_B}{{\mathrm{\λ}}_B}=(1-P_e){\mathrm{\ϵ}}_x\≈0.78\×{10}^{-6}{\mathrm{\ϵ}}_x$

ε in the formula _xBe microstrain, can calculate the theoretical gage factor of fiber grating by following formula, for example, as fiber grating λ _BDuring=1550nm, the strain sensitivity of fiber grating is: $\frac{\mathrm{\Δ}{\mathrm{\λ}}_B}{{\mathrm{\Δ\ϵ}}_x}\≈0.78\×{10}^{-6}\×{\mathrm{\λ}}_B=1.209\×{10}^{-3}\mathrm{nm}/\mathrm{\μ\ϵ}$

The wavelength variations of being measured by fiber grating, comparing with strain sensitivity just to obtain the distortion on road surface, surpasses permissible value and just represents to destroy, and needs road pavement to keep in repair.

Encapsulating material: glass fabric 04#, unsaturated polyester (UP) 191.Glass fabric is to form with fiberglass braided, appearance white, the hole of intuitively looking no.191 unsaturated polyester resins are a kind of moderately viscous liquid.Its glass fiber reinforced plastics product has good mechanical strength and higher extensibility, and trafficability characteristic is strong.Unsaturated polyester resin adopts monounsaturated dicarboxylic acid and unsaturated dibasic acid, and raw materials such as dibasic alcohol are synthetic, are dissolved in then in the cross-linking monomer styrene.Favorable manufacturability is arranged, energy rapid permeability glass fiber material, gel time is moderate.

Glass fibre and unsaturated polyester resin can protect grating sensor to survive in concrete after solidifying fully, and for the also not influence of intensity on road surface, the lead-in wire of optical fiber is drawn from the road surface side slope.When automobile was exercised from the road surface, sensor and road surface after the encapsulation are out of shape together, obtain wavelength variable quantity after, calculate concrete strain.

(4), description of drawings

Accompanying drawing is the structural representation of product of the present invention.

(5), specific embodiments

For example the present invention is done description in more detail below in conjunction with accompanying drawing:

The composition of imbedding the fiber-optic grating sensor in the highway comprises fiber Bragg grating sensor 5, and glass mat encapsulation 3 is arranged outside fiber Bragg grating sensor, is with protective casing 1 on the extended line 2 of Fiber Bragg Grating FBG.

Product of the present invention is to adopt such method to make: select for use Fiber Bragg Grating FBG as sensor; Fiber Bragg Grating FBG is penetrated in the protective casing; make the extended line of Fiber Bragg Grating FBG be arranged in protective casing; encapsulate then; concrete packaging technology is: the rectangle that glass fabric is cut into 240 * 40mm; totally 6, the prescription below unsaturated polyester resin adopts:

The composition weight portion

100 parts of 191 unsaturated polyester resins

2 parts of peroxidating methohexitones

Cobalt naphthenate 1-4 part

Wherein the consumption of cobalt naphthenate can suitably be selected in interval according to variation of temperature.

At glass upper berth layer of glass cloth, smear one deck unsaturated polyester resin, repave layer of glass cloth after being coated with evenly, when being taped against the 3rd layer, place fiber Bragg grating sensor, continue the lay glass fabric then, up to layer 6, after solidifying 1 hour at normal temperatures, periphery is cut finishing, after half an hour, scoop up from glass.

Claims (2)

1, a kind of fiber-optic grating sensor of imbedding in the highway, it is characterized in that: it comprises fiber Bragg grating sensor, and the glass mat encapsulation is arranged outside fiber Bragg grating sensor, is with protective casing on the extended line of Fiber Bragg Grating FBG.

2, a kind of method for packing of imbedding the fiber-optic grating sensor in the highway; it is characterized in that: select for use Fiber Bragg Grating FBG as sensor; the extended line of Fiber Bragg Grating FBG is penetrated in the protective casing; make the extended line of Fiber Bragg Grating FBG be arranged in protective casing; then Fiber Bragg Grating FBG and extended line are welded together, encapsulate at last, concrete packaging technology is: glass fabric is cut into rectangle; totally 6, the prescription below unsaturated polyester resin adopts:

The composition weight portion

100 parts of 191 unsaturated polyester resins

2 parts of peroxidating methohexitones

Cobalt naphthenate 1-4 part

At glass upper berth layer of glass cloth, smear one deck unsaturated polyester resin, repave layer of glass cloth after being coated with evenly, when being taped against the 3rd layer, place fiber Bragg grating sensor, continue the lay glass fabric then, up to layer 6, solidify after 1 hour, periphery is cut finishing, after half an hour, scoop up from glass.

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