CN201532269U - Fiber Bragg grating sensor used for measuring tri-axial pressures - Google Patents
Fiber Bragg grating sensor used for measuring tri-axial pressures Download PDFInfo
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- CN201532269U CN201532269U CN2009202471155U CN200920247115U CN201532269U CN 201532269 U CN201532269 U CN 201532269U CN 2009202471155 U CN2009202471155 U CN 2009202471155U CN 200920247115 U CN200920247115 U CN 200920247115U CN 201532269 U CN201532269 U CN 201532269U
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Abstract
The utility model provides a fiber Bragg grating FBG sensor used for measuring tri-axial pressures, and belongs to the field of testing instruments in civil engineering. The outline of the sensor adopts a cubic structure; the interior of the sensor is divided into a pressure measuring work cavity C1 and a line collecting cavity C2 through three square metal partition boards; the metal partition boards are normal to each other; and in the pressure measuring work cavity C1, three piezometric FBGs with the same physical parameter and the same structure are arranged on the metal partition boards, and a temperature compensation FBG is also mounted in the pressure measuring work cavity C1. When pressure is applied to a work membrane, the work membrane is bent and deformed so as to transmit the pressure to a dowel bar, and the dowel bar moves downwards so as to produce tensile strain of the piezometric FBGs; and when a beam of broadband light source passes through the piezometric FBGs, only light meeting Bragg diffraction can be reflected by the piezometric FBGs, so that ambient pressure can be measured by measuring the movement of the response wavelengths of the FBGs. The utility model can be used for simultaneously measuring stress states in three orthogonal directions of rock-soil body or a building in which the sensor is embedded, is suitable for departments such as highway departments, construction departments, mining industry department and the like, and has the advantages of convenient processing, simple structure, and low construction cost.
Description
Technical field
The utility model belongs to the civil engineering work field of test instrument, relates to the size of measuring the external pressure on three mutually perpendicular directions.
Background technology
At present, utilize Fiber Bragg Grating FBG (FBG) sensor of Bragg diffraction principle design to be widely used in the civil engineering work.In slope project, it can measure displacement, the STRESS VARIATION that sloping body slides and produces; In science of bridge building, can utilize fiber Bragg grating sensor that bridge is carried out health monitoring.
Fiber Bragg grating sensor is except that all advantages with ordinary optic fibre sensor, and also have the advantage of following uniqueness: 1. transducing signal is a wavelength-modulated, and measuring-signal is not subjected to the influence of light-intensity variation and instrument electromagnetic field; 2. have the self-reference point, measurement be absolute value; 3. easier employing wavelength-division multiplex technique is realized distributed sensing; 4. the grating fibre core that writes direct, it is simple in structure, good stability and insertion loss are low, is easy to realize that the one dimension photon is integrated.
The fiber Bragg grating sensor design concept is simple, and is cheap, can satisfy certain engineering survey needs.But following weak point is arranged also:
1) because this class sensor has only a Fiber Bragg Grating FBG, can only measure the pressure of single direction, can't measure the force value of other direction of observation station in stratum or the works simultaneously, promptly can't obtain the true stress state of observation station.
2) when measuring rock soil mass pressure, when having only horizontal positioned, could accurately measure by this class pressure transducer the displacement and the stress of rock soil mass.When the soil pressure sensor in being embedded in rock-soil layer produces owing to extraneous factor, can not accurately measure displacement and stress that rock soil mass needs interception.
When 3) this type of sensor is buried underground under the non-state that bankets, when burying underground such as the employing bore mode, no matter be level, vertical or inclined drill, it will very difficult exactly sensor being lain in a horizontal plane in the boring, and generation is than mistake when causing measuring the displacement of rock soil mass and stress.
The utility model content
The purpose of this utility model is to overcome the deficiency of existing fiber Bragg grating sensor, go out the sensor that to measure external pressure size on three mutually perpendicular directions simultaneously according to the Bragg diffraction principle design, and it is easy to process, simple in structure, cheap.
But the fiber Bragg grating sensor of three orthogonal directions pressure of the utility model synchro measure is primarily characterized in that:
1) profile is a cube structure, is made of three working masks 4 and three inoperative diaphragms 8, and inner square-shaped metal dividing plate 21 by three quadratures is divided into C1 of pressure survey work chamber and line concentration cavity C 2.
2) in the C1 of pressure survey work chamber, metal partion (metp) 21 is provided with three physical parameters and the identical pressure measurement optical fiber bragg grating FBG 1 of structure, can measure three orthogonal directions pressure simultaneously.
3) top board 9 is disc or square, the centre of form and working masks 4 center-aligned.Transmission rod 3 is perpendicular to top board 9 surfaces, and aligns with top board 9 centres of form.
4) lever 7 is fixed on the lever dolly 6, and an end of lever 7 contacts with transmission rod 3, and the other end and pressure measurement FBG 1 link.Pressure measurement FBG 1 one ends are clamped by pressure measurement FBG securing member 10, and the other end is clamped by the securing member on the lever 7.The FBG Fiber Bragg Grating FBG is arranged along metal partion (metp) 21 diagonal line.
5) because environment temperature can cause error to the measurement result of pressure measurement FBG 1, a temperature compensation FBG 2 is installed on metal partion (metp) 21, it experiences variation of temperature, but independent measurement goes out variation of temperature, thereby can isolate the variable quantity that pressure causes pressure measurement FBG 1.
6) three the pressure measurement FBG 1 of C1 and temperature compensation FBG 2 usefulness optical fiber are incorporated in the line concentration cavity C 2 in the pressure survey work chamber, carry out the cabling of optical fiber and arrange.
Do the time spent when working masks is stressed, an end that drives top board, transmission rod and lever produces downward displacement, causes the other end of lever to produce displacement upwards, thereby makes pressure measurement FBG produce stretching strain.When a branch of wide frequency light source during by pressure measurement FBG, pressure measurement FBG only reflects the light that satisfies Bragg diffraction in the incident light, be that fiber grating response wave length mobile is subjected to the variation in grating cycle and the influence of refraction index changing, by the size of measuring ambient pressure that moves of measuring optical fiber grating response wave length.
Because what the sensor internal measuring sensor adopted is optical fiber, its anti-electromagnetism, resistance to corrosion are strong, can adapt to bad working environment.Pressure measurement FBG and temperature compensation FBG in the C1 of pressure survey work chamber link with an optical fiber, therefore, can adopt multiplex technique, each grating is carried out Wavelength-encoding, like this, just a plurality of FBG can be connected in series, realize measurement along distribution field on the optical fibre installation path, thereby reduce the use of optical fiber, significantly reduce system cost.
The present invention can measure in the fiber Bragg grating sensor of triaxial pressure and be provided with three FBG (Bragg grating), can measure the external pressure of three orthogonal directionss simultaneously, its ultimate principle is that the grating that one section longitudinal refractive index cyclical variation is arranged is set in fiber optic core, the grating space of periodic refractive index change is therebetween represented with Λ, in the wide frequency light source injection fibre that general normal use such as light emitting diode, cold light diode, semiconductor laser produce, when its process grating, having only wavelength is λ
BLight can be reflected shown in (Fig. 5),
λ
B=2nΛ (1)
In the formula, n is the effective refractive index of fiber core.
When grating was subjected to external force and produces strain, causing former spacing was that the change increment of Λ is Δ Λ, and the substitution formula can obtain in (1)
Δλ
B=2nΔΛ (2)
Definition according to strain has
Obtain
Therefore, Λ is the spacing that refractive index cycle sexually revises, and has
The difference of FBG sensor and traditional resistance measurer maximum, be multiplex's characteristic of grating, be not limited to conditional electronic loop request signal transmission one to one, as long as when preparing grating, arrange the grating of different wave length to act on the same optical fiber, utilize the wide frequency light source of sufficient intensity, just can be at one time in one-shot measurement count the strain stress signal of point.If with traditional circuit arrangement, need to settle several electric wires, and between the electric wire each other because galvanomagnetic effect can the phase mutual interference, produce noise signal, influence the accuracy of measurement.The FBG sensor not only only needs one to two optical fiber to get final product, and does not take up space, and owing to there is not electromagnetic interference problem, as long as light source enough just can be connected in series in a large number, can keep higher precision.
Advantage of the present utility model is that independent measurement simultaneously acts on the external pressure on three mutually perpendicular directions on the working masks.When the pressure of this sensor application in measuring soil layer, can not be subjected to the influence of sensing station, measure observation station position in the soil layer and act on normal stress on three vertical direction of sensor surface, thereby understand the stress state of observation station place's rock soil mass or works.
Description of drawings
Fig. 1 is a three-dimensional FBG sensor internal structure three-dimensional plot.
Fig. 2 is a three-dimensional FBG sensor line concentration chamber interior optical fiber connection layout, comprises internal optical fiber top 13, internal optical fiber terminal 14.
Fig. 3 is a three-dimensional FBG sensor internal structure front elevation.
Fig. 4 is three-dimensional FBG working sensor diaphragm construction figure.
Fig. 5 is the FBG structural map.
Among the figure: grating, 18 protective seams, 19 grating spaces, 21 metal partion (metp)s are imbedded in 1-pressure measurement FBG (Fiber Bragg Grating FBG), 2-temperature compensation FBG, 3-transmission rod, 4-working masks, 5-optical fiber, 6-lever dolly, 7-lever, 8-inoperative diaphragm, 9-top board, 10-pressure measurement FBG securing member, 11-structure of fiber_optic, 12-temperature compensation FBG securing member, 13-internal optical fiber top, 14-internal optical fiber terminal, 15 incident lights, 16 reflected light, 17 holographies.
Embodiment
Further specify the utility model below in conjunction with accompanying drawing.
Fig. 1 is a kind of fiber Bragg grating sensor internal structure three-dimensional plot of measuring triaxial pressure, and metal partion (metp) is divided into C1 of pressure survey work chamber and line concentration cavity C 2 with sensor internal, and sensor is made up of three pressure measurement FBG and a temperature compensation FBG.
Fig. 2 is three-dimensional FBG sensor line concentration cavity C 2 optical fiber trace-diagram.In the three-dimensional FBG sensor, three pressure measurement FBG all are connected with an optical fiber with a temperature compensation FBG.Optical fiber is introduced into the line concentration cavity C 2 from the outside, as Fig. 2 internal optical fiber top 13.The optical fiber temperature compensation FBG that at first connects, and then three the pressure measurement FBG that connect successively draw line concentration cavity C 2, at last again as Fig. 2 internal optical fiber terminal 14.
Fig. 3 is the internal structure front elevation, and three pressure measurement FBG that design parameter is identical are installed on the metal partion (metp) of the C1 of pressure measurement work chamber.When measuring, cube working masks 4 directly contacts with the pressure that needs to measure.Deflection deformation takes place in working masks 4 effect of being stressed, and pressure is passed to transmission rod 3.Because of the end in contact of transmission rod 3, when transmission rod 3 effect of being stressed produces downward displacement, cause that just the other end of lever 7 produces displacement upwards, thereby make pressure measurement FBG 1 produce stretching strain with lever 7.When a branch of wide frequency light source during by pressure measurement FBG 1, satisfy the light of Bragg diffraction in 1 reflection of pressure measurement FBG incident light, be the influence that fiber grating response wave length mobile is subjected to the change of the variation in grating cycle and refractive index, by the size of measuring ambient pressure that moves of measuring optical fiber grating response wave length.When sensor internal is provided with three FBG, and arrange, just can satisfy the purpose of measuring three orthogonal directions pressure simultaneously by Fig. 2.
Fig. 4 is the working masks structural map, shows the relative position relation between working masks 4, top board 9, the transmission rod 3.Top board 9 is a disc, the centre of form and working masks 4 center-aligned.Transmission rod 3 is perpendicular to top board 9 surfaces, and aligns with top board 9 centres of form.When external pressure acted on working masks 4, working masks 4 produced inside distortion, and the deflection of the center passes to top board 9 equably, and then by transmission rod 3 deflection is passed to lever 7.
Fig. 5 is the FBG structural map, and the principle of work of FBG (Fiber Bragg Grating FBG) is described.When a branch of wide frequency light source passed through FBG, the light that satisfies Bragg diffraction in 17 reflections of grating incident light 15 was imbedded in holography.When the distortion that factors such as ambient pressure, temperature cause, the grating space 19 that causes holography to imbed grating 17 changes, and just causes holography to imbed moving of grating 17 response wave lengths.By measuring the size of measuring ambient pressure or temperature that moves of response wave length.
In a kind of manufacture process of the fiber Bragg grating sensor of measuring triaxial pressure, three pressure measurement FBG (Fiber Bragg Grating FBG) are installed on metal partion (metp) 21 at first.The position of passing through according to optical fiber on the metal partion (metp) 5 is stamped aperture earlier, then lever dolly 6, structure of fiber_optic 11 and pressure measurement FBG securing member 10 is mounted on the metal partion (metp) by welding or bolt.Lever 7 on the lever dolly 6 installs in advance.The last optical fiber 5 that has pressure measurement FBG 1 of placing again.After three FBG on the metal partion (metp) install, temperature compensation FBG 2 is installed again.When temperature compensation FBG 2 is installed, temperature compensation FBG securing member 12 is installed earlier, is placed the optical fiber that has temperature compensation FBG2 then.
After the metal partion (metp) that has three pressure measurement FBG is made, itself and three inoperative diaphragms 8 are welded together.Other three working masks 4 that have top board 9 and transmission rod 3 are made in advance.At last, by welding or bolt that its merging is as a whole.
The fiber Bragg grating sensor of the triaxial pressure of making measured is used for the while survey sensor and buries the rock soil mass at place or the stress state of three orthogonal directionss of works underground, is applicable to departments such as highway, building, mining industry.The utility model is easy to process, and is simple in structure, cheap.
Claims (3)
1. fiber Bragg grating sensor of measuring triaxial pressure, comprise pressure measurement optical fiber bragg grating FBG (1), temperature compensation FBG (2), transmission rod (3), working masks (4), optical fiber (5), lever dolly (6), lever (7), inoperative diaphragm (8), top board (9), pressure measurement FBG securing member (10), structure of fiber_optic (11), temperature compensation FBG securing member (12), metal partion (metp) (21), it is characterized in that:
1) profile is a cube structure, is made of three working masks (4) and three inoperative diaphragms (8), and inner square-shaped metal dividing plate (21) by three quadratures is divided into C1 of pressure survey work chamber and line concentration cavity C 2;
2) in the C1 of pressure survey work chamber, metal partion (metp) (21) is provided with three physical parameters and the identical pressure measurement optical fiber bragg grating FBG (1) of structure, measures three orthogonal directions pressure simultaneously;
3) top board (9) is disc or square, the centre of form and working masks (4) center-aligned, and transmission rod (3) is perpendicular to top board (9) surface, and aligns with top board (9) centre of form;
4) lever (7) is fixed on the lever dolly (6), one end of lever (7) contacts with transmission rod (3), the other end and pressure measurement FBG (1) link, pressure measurement FBG (1) one end is clamped by pressure measurement FBG securing member (10), the other end is clamped by the securing member on the lever (7), and pressure measurement FBG (1) arranges along metal partion (metp) (21) diagonal line.
2. the fiber Bragg grating sensor of measurement triaxial pressure as claimed in claim 1 is characterized in that: a temperature compensation FBG (2) also is installed on the described metal partion (metp) (21).
3. the fiber Bragg grating sensor of measurement triaxial pressure as claimed in claim 1, it is characterized in that: three pressure measurement FBG (1) in the C1 of pressure survey work chamber and temperature compensation FBG (2) link with same optical fiber (5), are incorporated in the line concentration cavity C 2.
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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CN102620870A (en) * | 2012-04-05 | 2012-08-01 | 中国科学院武汉岩土力学研究所 | Rock three-way pressure stress sensor based on optical fiber grating sensing |
CN103353367A (en) * | 2013-07-04 | 2013-10-16 | 中山大学 | Rock and soil reinforcement bar outer end force sensor based on fiber bragg grating |
CN105651425A (en) * | 2014-12-08 | 2016-06-08 | 航天长征火箭技术有限公司 | Three-dimensional pressure sensor detecting granary reserves |
CN107300363A (en) * | 2016-05-12 | 2017-10-27 | 中国计量大学 | A kind of positive tetrahedron optical fibre grating three-dimensional strain detecting structure |
CN107907252A (en) * | 2017-10-23 | 2018-04-13 | 沈阳建筑大学 | A kind of lever fiber bragg grating pressure sensor |
CN113804348A (en) * | 2021-09-22 | 2021-12-17 | 中国核动力研究设计院 | Optical fiber FBG sensor and system for measuring pressure of high-energy pipeline of nuclear power device |
-
2009
- 2009-11-23 CN CN2009202471155U patent/CN201532269U/en not_active Expired - Fee Related
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102620870A (en) * | 2012-04-05 | 2012-08-01 | 中国科学院武汉岩土力学研究所 | Rock three-way pressure stress sensor based on optical fiber grating sensing |
CN103353367A (en) * | 2013-07-04 | 2013-10-16 | 中山大学 | Rock and soil reinforcement bar outer end force sensor based on fiber bragg grating |
CN103353367B (en) * | 2013-07-04 | 2016-10-26 | 中山大学 | A kind of rock-reinforcing rod member outer end based on fiber grating force cell |
CN105651425A (en) * | 2014-12-08 | 2016-06-08 | 航天长征火箭技术有限公司 | Three-dimensional pressure sensor detecting granary reserves |
CN107300363A (en) * | 2016-05-12 | 2017-10-27 | 中国计量大学 | A kind of positive tetrahedron optical fibre grating three-dimensional strain detecting structure |
CN107907252A (en) * | 2017-10-23 | 2018-04-13 | 沈阳建筑大学 | A kind of lever fiber bragg grating pressure sensor |
CN113804348A (en) * | 2021-09-22 | 2021-12-17 | 中国核动力研究设计院 | Optical fiber FBG sensor and system for measuring pressure of high-energy pipeline of nuclear power device |
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