Summary of the invention
The purpose of the present invention is to solve this problem, providing one kind being capable of precise measurement structural member in a certain rangeThe packaging method of the substrate formula optical fibre Bragg optical grating strain sensor of strain, can precise measurement environment temperature, reach decouplingPurpose, and demarcated in laboratory environment pair of strain sensors, test sensor Compression and Expansion performance.Using novel baseChip package method can effectively transmit strain, realize strain measurement.
For achieving the above object, the technical scheme is that
A kind of packaging method of optical fibre Bragg optical grating strain sensor, which comprises the steps of: 1) gratingBefore fibre optic strain sensor encapsulation, mechanical simulation analysis is carried out to the grating fibers strain transducer；
2) the grating fibers strain transducer encapsulation；
3) the grating fibers strain transducer calibration.
Preferably, mechanical simulation is analyzed, and steps are as follows, and 11, which carry out gridding to sensor with finite element method, drawsPoint；12 simulation extension test loading procedures fix sensor substrate one end, and the other end applies pulling force and stretched, and are simulated with thisWhen adhering to the measured object surface from tensile of sensor, the stress of sensor.
Preferably, in the strain transducer encapsulation process, steps are as follows, and 21, by adjustable optic fibre fixture, apply pre-Clamp force increases two fiber bragg grating center wavelengths, epoxide-resin glue is smeared at sensor substrate A, B, using full coverage typeIt encapsulates at sensor substrate C, for measuring temperature parameters；22 after the completion of dispensing, installs the biography of fiber grating under room temperature state additionalSensor substrate stands setting time, is then socketed fiber optic protection casing and fixation, high-temperature decoupling essence in sensor base two sidesThe encapsulation for spending enhanced sensitivity formula strain fiber-optic grating sensor is completed.
Preferably, the strain transducer calibration, steps are as follows, and 31 build test sensor enhanced sensitivity pilot system, usesMTS cupping machine using KYOWA foil gauge acquisition numerical value as standard strain value, and sets up half-bridge a pair using resistance strain gageOne compensation circuit is compared with the naked mounted packaged fiber grating strain transducer in same level section；32 will answer in high precisionBecome tester and high speed optic fiber grating demodulation module and LabVIEW software is write by host computer, realizes strain transducer inThe long synchronous acquisition storage of cardiac wave；33 in collection process, program-controlled setting cupping machine, under conditions of giving initial tensile forceIt is incremented by pulling force step by step, does two tension and compression circulations by reading foil gauge output numerical value and survey the relationship between pulling force and strain.
Compared with prior art, the beneficial effects of the present invention are:
Improved in the technique of traditional strain transducer, can simultaneously precise measurement environment temperature, reachThe purpose of decoupling, and demarcated in laboratory environment pair of strain sensors, test sensor Compression and Expansion performance.Using novelSubstrate formula packaging method, realize strain measurement.Base material chooses the preferable aerolite 7075-T6 of Compression and ExpansionBase material can effectively transmit strain, achieve the purpose that measure enhanced sensitivity.The temperature decouples enhanced sensitivity formula strain transducer canEffectively reliable accurate means of testing is provided for wing structure Compression and Expansion.
Specific embodiment
Below in conjunction with attached drawing, technical scheme in the embodiment of the invention is clearly and completely described.
As shown in Figs 1-4, a kind of optical fibre Bragg optical grating strain sensor includes the following steps: 1) grating fibers strainBefore sensor encapsulation, mechanical simulation analysis is carried out to the grating fibers strain transducer；
Fiber Bragg grating strain sensor structure as shown in Figure 1.As shown in figure 3, mechanical simulation is analyzed, steps are as follows, and 11 useFinite element method carries out gridding division to sensor；12 simulation extension test loading procedures keep sensor substrate one end solidFixed, the other end applies pulling force and is stretched, and is simulated with this when adhering to the measured object surface from tensile of sensor, sensorStress.
Load is applied to substrate and carries out finite element analysis.According to stress cloud atlas, it can be concluded that, tensile stress occurs for sensorWhen variation, the special shape of substrate concentrates on substrate deformation between A, B two o'clock, forms stress and concentrates, not will receive biography at CSensor stretches bring any influence, i.e., any deformation does not occur.From the angle of force analysis, it is believed that the sensor baseDesign can reach expected purpose.
2) the grating fibers strain transducer encapsulation；
As shown in Fig. 2, steps are as follows in the strain transducer encapsulation process, 21, by adjustable optic fibre fixture, applyPretightning force makes two fiber bragg grating center wavelengths increase 1nm, and DP420 epoxide-resin glue is smeared at sensor substrate A, B, is adoptedAt full coverage type encapsulation sensor substrate C, for measuring temperature parameters；22 after the completion of dispensing, installs light additional under room temperature stateThe sensor substrate of fine grating stands setting time 24 hours, is then socketed fiber optic protection casing in sensor base two sides and consolidatesFixed, the encapsulation that high-temperature decouples precision enhanced sensitivity formula strain fiber-optic grating sensor is completed；The lesser fiber grating of central wavelength is adoptedIt is encapsulated with full coverage type.
According to theory analysis and purpose of design, sensor is pasted onto testee surface, at affixed points D, E two, then increasesQuick multiple is LDE/LAB.
3) the grating fibers strain transducer calibration.
The strain transducer calibration, steps are as follows, and 31 build test sensor enhanced sensitivity pilot system, is stretched using MTSTesting machine, using KYOWA foil gauge acquisition numerical value as standard strain value, and it is one-to-one compensation using resistance strain gage establishment half-bridgeCircuit is compared with the naked mounted packaged fiber grating strain transducer in same level section；32 by high-precision strain testing instrumentAnd high speed optic fiber grating demodulation module writes LabVIEW software by host computer, realizes strain transducer and central wavelengthSynchronous acquisition storage；33 in collection process, and program-controlled setting cupping machine is incremented by step by step under conditions of giving initial tensile forcePulling force does two tension and compression circulations by reading foil gauge output numerical value and surveys the relationship between pulling force and strain.
In order to test sensor effect of enhanced sensitivity, if Fig. 4 shows, the fiber Bragg grating strain sensor calibration enhanced sensitivity test is builtSystem is to be attached to same level section high-precision KYOWA foil gauge acquisition numerical value with sensor using MTS cupping machineStandard strain value, and the one-to-one compensation circuit of half-bridge is set up using same performance resistance strain gage, it is naked with same level sectionMounted packaged fiber grating strain transducer compares.
During strain transducer and the synchronous acquisition of central wavelength, according to the Young's modulus and cross of tension test partCross-sectional dimension applies the clamping pulling force of 8000N, reaches and need microstrain value.Sigma high-precision strain testing instrument is chosen, mostSmall resolution ratio 1 μ ε, maximum frequency acquisition 500Hz；MTS cupping machine, maximum pull 250000N；Temperature calibration link is sameFlat wideband light source and Ibsen high speed optic fiber grating (FBG) demodulator；No. 45 steel are tensioning member.
In the case of obtaining continuous time, changing rule synchronous with central wavelength is strained, Sigma high-precision is strainedTester and Ibsen high speed (FBG) demodulator write LabVIEW software by host computer, realize strain transducer and central wavelengthSynchronous acquisition storage.
If Fig. 5 shows in collection process, program-controlled setting cupping machine, under conditions of giving initial 2000N pulling force, with1000N, which is stepping, is incremented to 10000N step by step, is drawn-pressure-draws-presses two circulations, real by reading foil gauge output numerical valueSurvey the relationship between pulling force and strain, fitting function formula 1 are as follows:
ε=0.065F-33.635；R2=0.999 (1)
During investigating effect of enhanced sensitivity, the linearity and the repeatability of enhanced sensitivity formula strain transducer, answered with enhanced sensitivity formulaThe same cross-section location for becoming sensor is pasted with the different naked mounted fiber Bragg grating strain sensor of central wavelength, obtains not enhanced sensitivityIn the case of fiber grating survey strain sensitivity coefficient, while using serial temperature compensated optical fiber grating method, exclude temperatureInfluence of the parameter to test result.Ambient temperature effect is excluded by algorithm, value of thrust and enhanced sensitivity formula strain transducer are reflectedCentral wavelength carries out least square fitting, show that its relation curve such as Fig. 6 shows, fitting function and linearity formula 2 be,
λ=9.47 × 10-5F+1537.646；R2=0.999 (2)
Linearity coefficient of determination R2=0.9991, the linearity are good.
Convolution 1, obtain enhanced sensitivity formula strain transducer central wavelength and substrate institute it is strained between relation function formula 3 are as follows:
λ=1.46 × 10-3ε+1537.696 (3)
Effect of enhanced sensitivity and repeatability are to investigate the important indicator of sensor performance, exclude ambient temperature effect by algorithmAfterwards, two different performance strain transducers acquired reflection kernel wavelength data is recycled in Compression and Expansion twice to carry out at algorithmReason, the departure of central wavelength when obtaining stable point fiber grating reflection kernel wavelength and value of thrust 2000N, and carry out respectively mostSmall two multiply fitting, investigate the value of two slope of curve multiples and stepping stable case lower pulling force, and fitting function such as Fig. 7 shows, are fitted letterNumerical expression 4 are as follows:
By analyzing fitting data, enhanced sensitivity formula strain transducer effect of enhanced sensitivity is obvious, reaches 0.095/0.068=1.4 times.
By Fig. 8 to draw a conclusion, enhanced sensitivity formula strain transducer repeats sexual deviation and is no more than ± 5pm, and error is to test resultBring influences to be no more than 3 μ ε, within the allowable range, it is believed that repeatability is good, and the design is feasible.
Embodiments described above is only a part of the embodiment of the present invention, instead of all the embodiments.Based on thisEmbodiment in invention, every other reality obtained by those of ordinary skill in the art without making creative effortsExample is applied, shall fall within the protection scope of the present invention.