CN109405763A - A method of it is strained using fiber-optic grating sensor precise measurement spacecraft - Google Patents
A method of it is strained using fiber-optic grating sensor precise measurement spacecraft Download PDFInfo
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- CN109405763A CN109405763A CN201811407669.7A CN201811407669A CN109405763A CN 109405763 A CN109405763 A CN 109405763A CN 201811407669 A CN201811407669 A CN 201811407669A CN 109405763 A CN109405763 A CN 109405763A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/165—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by means of a grating deformed by the object
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Abstract
The invention discloses a kind of methods strained using fiber-optic grating sensor precise measurement spacecraft, for " having metallic substrates " fiber-optic grating sensor, establish fiber-optic grating sensor model, by considering body thickness to be measured in strain transmitting, bulk modulus to be measured, Adhesive thickness, after fiber core height and Elastic Modulus of Adhesive influence, obtain carry-over factor, strain measured value is modified using carry-over factor, it is achieved in the accuracy of fiber-optic grating sensor strain measurement on spacecraft, realize that the accurate measurement of strain provides guarantee for fiber-optic grating sensor on spacecraft.
Description
Technical field
The invention belongs to technical field of optical fiber sensing, and in particular to a kind of application fiber-optic grating sensor precise measurement space flight
The method of device strain.
Background technique
Fiber-optic grating sensor measurement strain is broadly divided into " band metallic substrates " sensor and " without metallic substrates " sensing
Two kinds of forms of device (bare fibre).In the in-orbit flight course of spacecraft, harsh environmental conditions are complicated, in order to improve fibre optical sensor
Safety and stability measurement, general to use the fiber-optic grating sensor with metallic substrates, metallic substrates play good protection
Effect.
In strain measurement, with metallic substrates fiber-optic grating sensor obtain body surface strain value often with foil gauge
It is inconsistent to measure obtained strain, the strain that the former measures is less than the latter, and the strain that foil gauge measures is typically considered to more connect
It is bordering on the strain that object actually occurs.By analyzing the measuring principle discovery with metallic substrates fiber-optic grating sensor, measurement
Object strain can be just eventually transferred to by four adhesive, metallic substrates, glass solder, optical fiber coating intermediate mediums
Fiber core and cause reflection wavelength to change, dielectric material mismatch and sensor structure parameter etc. due to cause strain to exist
It may be lost when being transmitted in above-mentioned medium, the strain that final fiber core measures cannot reflect really answering for object
Become, it is necessary to which quantitative analysis is carried out to the process of strain transmitting.
When Fibre Optical Sensor is measured and strained, the ratio for defining strain measurement value and actual strain value is carry-over factor, transmitting
The accuracy of coefficient directly determines the accuracy of strain measurement value.
There are many influence factor of carry-over factor, for the carry-over factor of the fiber-optic grating sensor of " without metallic substrates ",
Existing related work reported the principal element for influencing carry-over factor.
2007, Zhou Guangdong of Dalian University of Technology etc. obtained influence on the basis of straining transfer theory by analysis
The principal element of the fiber-optic grating sensor strain transmitting of " without metallic substrates ", the i.e. length of fiber-optic grating sensor, centre
Thickness, elasticity modulus and the Poisson's ratio of layer, and obtain influence of each factor to fiber grating measurement accuracy.
2008, the king of University Of Tianjin was etc. in the fiber-optic grating sensor transmittance process having studied " without metallic substrates "
Influence of the substrate to strain transfer ratio, the influence of simulation analysis substrate thickness and cohesive length to strain transmission effect.
2010, the measurement that Shenyang Building Univ. Sun Li etc. has studied the fiber-optic grating sensor " without metallic substrates " was answered
Calculation formula is transmitted in the strain become between base structure actual strain, and is analyzed to it using finite element method and discussed temperature
Influence of the degree variation to the fiber grating strain transmitting under non-axial applied force.
2013, the Zhang Wenxiao etc. of Hohai University had studied the strain transmitting of the fiber-optic grating sensor " without metallic substrates "
Influence factor, obtain each factor to the influence degree of strain transfer ratio.
2014, the optical fiber Bragg grating sensing to influence " without metallic substrates " such as field stone column of Suzhou Institute of Science and Technology
The influence factor of device average strain transfer rate has carried out theory analysis, obtain bonding layer elasticity modulus, bonding layer width and
The stickup length of optical fiber is affected to strain transfer ratio, the optimal combination being determined by experiment between them.
2016, the Zhang Zhenglin etc. of liberation army Polytechnics had studied adhesive to the fiber grating of " without metallic substrates "
The influence of strain transducer carry-over factor, test discovery, adhesive is bigger in the shear strength of matrix surface, optical fiber grating sensing
The strain transfer coefficient of device is also bigger.
And for the spacecraft fiber-optic grating sensor of " with metallic substrates ", it retrieves less than the systematicness to carry-over factor
Research or method.
Summary of the invention
In view of this, the object of the present invention is to provide it is a kind of using fiber-optic grating sensor precise measurement spacecraft strain
Method, available accurate carry-over factor, and then realize the accuracy of fiber-optic grating sensor strain measurement on spacecraft.
A method of it measures and strains using fiber-optic grating sensor, include the following steps:
Firstly, establishing the limit element artificial module that fiber-optic grating sensor (2) is mounted on body to be measured (3)；Wherein, optical fiber
The metallic substrates (22) of grating sensor (2) are fixed on body to be measured (3) surface by adhesive (21)；
Secondly, defining body to be measured (3) surface X-Z plane, the fiber core (25) of X-direction and fiber-optic grating sensor (2)
Length direction is consistent, Z axis vertical X axis, and Y-axis is determined according to right-hand screw rule, thus establishes rectangular coordinate system XYZ；
Again, metallic substrates (22) structure of input optical fibre grating sensor (2) is joined in the limit element artificial module
Number and body (3) thickness to be measured, the elasticity modulus of body to be measured (3), adhesive (21) thickness, fiber core (25) are highly and viscous
Jelly (21) elasticity modulus；It constrains body to be measured (3) end face to be displaced along Y and Z-direction, applies X-shift load to it, extract
Fiber core (25) average displacement Δ lFWith body to be measured (3) and adhesive (21) contact zone outer boundary average displacement Δ lB；By as follows
Formula calculates strain transfer coefficient γ:
Finally, utilizing γ pairs of strain transfer coefficient when application fiber-optic grating sensor (2) measures body (3) to be measured displacement
The measured value of fiber-optic grating sensor (2) is modified.
The invention has the following beneficial effects:
The present invention establishes fiber-optic grating sensor model, by examining for " having metallic substrates " fiber-optic grating sensor
Consider body thickness, bulk modulus to be measured, Adhesive thickness, fiber core height and Elastic Modulus of Adhesive to be measured in strain transmitting
After influence, carry-over factor is obtained, strain measured value is modified using carry-over factor, fiber-optic grating sensor is achieved in and exists
The accuracy of strain measurement on spacecraft realizes that the accurate measurement of strain provides guarantor for fiber-optic grating sensor on spacecraft
Barrier.
Detailed description of the invention
Fig. 1 is that carry-over factor calculates finite element model.
Fig. 2 is the corresponding strain transfer coefficient of difference body thickness to be measured.
Fig. 3 is the corresponding strain transfer coefficient of difference bulk modulus to be measured.
Fig. 4 is the corresponding strain transfer coefficient of different adhesive thickness.
Fig. 5 is the corresponding strain transfer coefficient of different adhesive elasticity modulus.
Strain transfer coefficient when Fig. 6 is different fiber core positions.
Fig. 7 is weighing factor of the different factors to strain transfer coefficient.
Fig. 8 is certain satellite bulkhead plan and carry-over factor accuracy testing check post.
Fig. 9 is that the carry-over factor after comprehensively considering five factors is compared with carry-over factor measurement result is not considered.
Wherein, 1- satellite cabin, 2- fiber-optic grating sensor, 3- body to be measured, 21- adhesive, 22- metallic substrates, 23- light
Fine coat, 24- glass solder, 25- fiber core.
Specific embodiment
The present invention will now be described in detail with reference to the accompanying drawings and examples.
The present invention strains indeterminable problem for the fiber-optic grating sensor on spacecraft " with metallic substrates ", provides
A method of it is strained using fiber-optic grating sensor precise measurement spacecraft: determining the fiber grating with metallic substrates 22 first
The structure of sensor 2 has fiber core 25 in fiber-optic grating sensor 2, and there is optical fiber coating in the outer surface of fiber core 25
23；The metallic substrates 22 of the lower surface setting of fiber-optic grating sensor 2 are fixed on 3 surface of body to be measured by adhesive 21；
3 surface strain of body to be measured is transmitted to the metallic substrates 22 of fiber-optic grating sensor 2 by adhesive 21, then by metal
Substrate 22 is transmitted to fiber core 25 by the glass solder 24 between optical fiber coating 23 and metallic substrates 22, causes fiber reflection
Wavelength change.
If the measurement volume length that 3 surface of body to be measured is contacted with adhesive 21 is lB, it is displaced as Δ lB, 3 surface measurement of body to be measured
Area's strain is εB, the distance between 2 two glass solders 24 of coat of fiber-optic grating sensor are lF, it is displaced as Δ lF, optical fiber fibre
The strain of core 25 is εFThen have:
η is sensor desensitization coefficient, and is had:
Strain transfer coefficient γ are as follows:
It can be obtained according to formula (1)~(3):
By formula (4) it is found that fiber-optic grating sensor 2 for " with metallic substrates 22 ", strain transfer coefficient can be by light
Long and slender core 25 is in two glass solder point position displacement Δ lFWith 3 measurement zone displacement l of body to be measuredBIt acquires.
The finite element model of body 3 to be measured, adhesive 21 and fiber-optic grating sensor 2 is established, it is flat with 3 surface X-Z of body to be measured
Face, X-direction is consistent with the core length direction of fibre optical sensor, Z axis vertical X axis, and Y-axis is determined according to right-hand screw rule, by
This establishes rectangular coordinate system XYZ；
Finite element model input optical fibre grating sensor 23 thickness of 22 structural parameters of metallic substrates and body to be measured,
Elasticity modulus, 21 thickness of adhesive, 25 height of fiber core and 21 elasticity modulus of adhesive of body 3 to be measured；Constrain 3 end of body to be measured
Face is displaced along Y, Z-direction, applies X-shift load, extracts fiber core 25 in two glass solder point position average bits
Move Δ lF(F point X-shift as shown in Figure 1) and body to be measured 3 and 21 contact zone outer boundary average displacement Δ l of adhesiveB(such as
The point of B shown in Fig. 1 X-shift), calculate strain transfer coefficient γ.
When measuring body 3 to be measured displacement using fiber-optic grating sensor 2, fiber grating is passed using strain transfer coefficient γ
The measured value of sensor 2 is modified, and is achieved in and is carried out precise measurement to body 3 to be measured.
Embodiment:
Fig. 1 is that carry-over factor calculates finite element model.Establish body 3 to be measured, adhesive 21 has with fiber-optic grating sensor 2
Meta-model is limited, a quarter symmetry model is established according to the symmetry of model and is calculated, model (section) is as shown in Figure 1.
The material that simulation model includes is as shown in table 1.
1 simulation model of table includes material
3 end face of body to be measured is constrained along Y, Z-direction freedom degree, applies X-shift load, extracts fiber core 25 two
A equal displacement l of glass solder point horizontalizationFWith body 3 and 21 contact zone outer boundary average displacement Δ l of adhesive to be measuredB, calculating answers
Become carry-over factor γ.
Fig. 2 is the corresponding strain transfer coefficient of difference 3 thickness of body to be measured.Strain transfer coefficient increases with 3 thickness of body to be measured
And increase, during 3 thickness of body to be measured changes to 10mm from 5mm, strain transfer coefficient changes to 0.862 from 0.850.
Fig. 3 is the corresponding strain transfer coefficient of difference 3 elasticity modulus of body to be measured.Strain transfer coefficient is with 3 elasticity of body to be measured
The increase of modulus and reduce, 3 elasticity modulus of body to be measured is from 3 × 10-10Pa changes to 2.1 × 10-9During Pa, strain transmitting
Coefficient changes to 0.862 from 0.850.
Fig. 4 is the corresponding strain transfer coefficient of different 21 thickness of adhesive.Strain transfer coefficient is with 21 thickness of adhesive
Increase and reduce, during 21 thickness of adhesive changes to 0.1mm from 0.01mm, strain transfer coefficient is changed to from 0.850
0.862。
Fig. 5 is the corresponding strain transfer coefficient of different 21 elasticity modulus of adhesive.Strain transfer coefficient is with 3 elasticity of body to be measured
The increase of modulus and increase, 21 elasticity modulus of adhesive is from 1 × 109Pa changes to 1 × 1010During Pa, strain transmitting system
Number changes to 0.87 from 0.82.
Fig. 6 is influence of different 25 positions of fiber core to strain transfer coefficient.Strain transfer coefficient is with core height
Increase and increase, during core height changes to 0.39mm from 0.31mm, strain transfer coefficient is changed to from 0.852
0.866。
Fig. 7 is different factors to the weighing factor of strain transfer coefficient, as can be seen from FIG. 7 25 position of fiber core, glue-line
Thickness influences strain transfer coefficient maximum；Maximum factor is influenced on carry-over factor by determining in five factors, is being sensed
The stabilization for ensuring the factor of larger impact when device design and installation thereby guarantees that the precision of sensor.
Fig. 8 is that certain satellite bulkhead plan and carry-over factor accuracy testing check post are chosen.In order to verify multifactor association
With the accuracy for the carry-over factor that emulation obtains, fiber-optic grating sensor 2 is pasted in the bulkhead A point of certain satellite cabin 1 to measure
Strain, while close to 2 side adhering resistance strain sheets of fiber-optic grating sensor, using the measured value of resistance strain gage as strain
Standard value measures the accuracy of strain value convenient for assessment fiber-optic grating sensor 2.
In test verifying, satellite bulkhead is aluminium alloy (elasticity modulus 72GPa) thin-wall construction of wall thickness 5mm, adhesive
21 with a thickness of 0.05mm, and metallic substrates 22 are SUS304 (elasticity modulus 200GPa), 25 height 0.6mm of fiber core, will be with
Upper 5 parameters substitute into simulation calculation, and strain transfer coefficient is 0.87 at this time.
Fig. 9 be comprehensively consider it is multifactor after carry-over factor and do not consider carry-over factor measurement result comparison diagram.Square
When point and line chart expression does not consider carry-over factor, 2 strain measurement value of fiber-optic grating sensor and resistance strain gage strain measurement value
Relation curve, the two linear relationship slope are 0.86, illustrate that the strain measurement absolute error of fiber-optic grating sensor 2 is larger.Circle
When form point line chart indicates to consider the carry-over factor that emulation obtains, 2 strain measurement value of fiber-optic grating sensor is answered with resistance strain gage
Become the relation curve of measured value, the two linear relationship slope is 0.99, illustrates that the strain measurement of fiber-optic grating sensor 2 absolutely misses
Difference is smaller.
By Fig. 9, provide before and after considering carry-over factor, the absolute error of strain measurement, as shown in table 2, serial number 1-16 generation
Table constantly pressurizes to satellite cabin and improves the process of cabin strain value, and the standard of resistance strain gage strain measurement is listed in table
Value considers the front/rear 2 strain measurement value of fiber-optic grating sensor of carry-over factor, considers the front/rear fiber-optic grating sensor of carry-over factor
The absolute error of 2 measurement strains.
It can be found that before fiber-optic grating sensor 2 carries out strain correction by the carry-over factor that emulation obtains, absolute error
Variation range is -45.41 μ μ of ε~-127.56 ε；Fiber-optic grating sensor 2 should turn revisionism by the carry-over factor that emulation obtains
After just, absolute error variation range is the 0.02 μ ε of μ ε~10.23, and strain measurement result is more accurate.
Table 2 considers strain measurement value absolute error before and after carry-over factor
In conclusion the above is merely preferred embodiments of the present invention, being not intended to limit the scope of the present invention.
All within the spirits and principles of the present invention, any modification, equivalent replacement, improvement and so on should be included in of the invention
Within protection scope.
Claims (1)
1. a kind of method using fiber-optic grating sensor measurement strain, which comprises the steps of:
Firstly, establishing the limit element artificial module that fiber-optic grating sensor (2) is mounted on body to be measured (3)；Wherein, fiber grating
The metallic substrates (22) of sensor (2) are fixed on body to be measured (3) surface by adhesive (21)；
Secondly, body to be measured (3) surface X-Z plane is defined, fiber core (25) length of X-direction and fiber-optic grating sensor (2)
Direction is consistent, Z axis vertical X axis, and Y-axis is determined according to right-hand screw rule, thus establishes rectangular coordinate system XYZ；
Again, in the limit element artificial module input optical fibre grating sensor (2) metallic substrates (22) structural parameters, with
And body (3) thickness to be measured, the elasticity modulus of body to be measured (3), adhesive (21) thickness, fiber core (25) height and adhesive
(21) elasticity modulus；It constrains body to be measured (3) end face to be displaced along Y and Z-direction, applies X-shift load to it, extract optical fiber
Fibre core (25) average displacement Δ lFWith body to be measured (3) and adhesive (21) contact zone outer boundary average displacement Δ lB；By following formula
Calculate strain transfer coefficient γ:
Finally, when application fiber-optic grating sensor (2) measures body (3) to be measured displacement, using strain transfer coefficient γ to optical fiber
The measured value of grating sensor (2) is modified.
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Cited By (3)
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| CN110836643A (en) * | 2019-11-08 | 2020-02-25 | 中国人民解放军海军七0一工厂 | Measurement of temperature bending deformation of curved surface piezoelectric composite material |
| CN112212796A (en) * | 2020-09-27 | 2021-01-12 | 山东航天电子技术研究所 | Method for consistently installing and calibrating strain rosette sensor of three-dimensional fiber bragg grating |
| CN112629400A (en) * | 2020-12-02 | 2021-04-09 | 山东航天电子技术研究所 | Method for realizing high-precision measurement of strain of cylindrical metal body based on optical fiber sensing |
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Application publication date: 20190301 |