CN106769840A - The measuring method of the rolling contact point transient state side-friction coefficient based on fiber grating - Google Patents
The measuring method of the rolling contact point transient state side-friction coefficient based on fiber grating Download PDFInfo
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- CN106769840A CN106769840A CN201610820853.9A CN201610820853A CN106769840A CN 106769840 A CN106769840 A CN 106769840A CN 201610820853 A CN201610820853 A CN 201610820853A CN 106769840 A CN106769840 A CN 106769840A
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- bull wheel
- fiber grating
- steamboat
- fiber
- contact point
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N19/00—Investigating materials by mechanical methods
- G01N19/02—Measuring coefficient of friction between materials
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D21/00—Measuring or testing not otherwise provided for
- G01D21/02—Measuring two or more variables by means not covered by a single other subclass
Abstract
The invention discloses a kind of measuring method of the rolling contact point transient state side-friction coefficient based on fiber grating, comprise the following steps：The different fiber grating of centre wavelength is symmetrically pasted on the both sides of bull wheel, and label successively；Regulation bull wheel produces certain normal force with steamboat at rolling contact point, and makes to produce certain angle of attack between bull wheel and steamboat, so that bull wheel produces certain cross force at rolling contact point；The rotating speed of bull wheel is controlled, when bull wheel rotates, the strain signal that bull wheel is produced passes to fiber grating, and the built-in light source of (FBG) demodulator is transferred in each fiber grating by fiber grating rotary connector, and fiber grating produces strain signal；Be demodulated for the strain signal of fiber grating by (FBG) demodulator, and demodulated signal is sent into industrial computer, and industrial computer is acquired to demodulated signal and calculates transient state normal pressure and frictional force of the bull wheel at rolling contact point with analysis, the wave length shift according to fiber grating.
Description
Technical field
It is horizontal the present invention relates to optical fiber grating sensing field, more particularly to a kind of rolling contact point transient state based on fiber grating
To the measuring method and device of coefficient of friction.
Background technology
Fiber grating sensing technology grows up on the basis of optical fiber sensing technology, fiber grating sensing system base
Present principles are that multiple gratings (respectively with different centre wavelength), the light wave sent by wideband light source have been concatenated on an optical fiber
By shunt by all of grating, reflected light is led to through another interface coupled into optical fibres grating demodulation instrument of shunt
Cross fiber Bragg grating (FBG) demodulator to measure wavelength and its change of reflected light, it is possible to obtain demodulating data, then dividing by data
Analysis and treatment, it is possible to obtain the variable quantity of environment at corresponding each fiber grating, such as temperature, stress.Analyzed from principle,
Fiber-optic grating sensor not only has the advantages that general Fibre Optical Sensor, while overcoming the deficiency of some Fibre Optical Sensors
Place, can realize real-time online, the measurement of absolute number formula, with measurement range is wide, high precision, strong antijamming capability, need not zeroing,
Good long term stability, to realize the high resolution of vibrating sensing, high s/n ratio, high fidelity, fine definition, high-precision
Exactness and confidence level high provide preferable technological means, are all with a wide range of applications in various fields.
Fiber grating is the important component of fiber-optic grating sensor.As a kind of optic fibre passive device, optical fiber
Grating develops extremely rapid in recent years.With the constantly improve of fiber grating manufacturing technology, the increasingly extension of application field, light
Fine grating has turned at present most one of fiber optic passive device of development prospect.Fiber Bragg Grating FBG (FBG) is at present in light
Most grating in fibre sensing, and cross sensitivity problem is to restrict the protrusion that fiber-optic grating sensor further develops
Problem.To strain and temperature all it is sensitive, i.e. optical fiber due to grating Bragg wavelength in optical fiber grating sensing practical application
Grating sensor has strain, Temperature cross-over tender subject, when fiber grating is used for sensing measurement, single optical fiber Bragg
Grating cannot tell the change of the bragg wavelength that strain and temperature cause respectively in itself, and then cannot realize accurate survey
Amount.
The content of the invention
The technical problem to be solved in the present invention is that cannot divide in itself for single Fiber Bragg Grating FBG in the prior art
The change of the bragg wavelength that strain and temperature cause respectively is discerned, so as to the defect of accurate measurement cannot be realized, there is provided a kind of
The measuring method and device of the rolling contact point transient state side-friction coefficient based on fiber grating of accurate measurement can be realized.
The technical solution adopted for the present invention to solve the technical problems is：
A kind of measuring method of the rolling contact point transient state side-friction coefficient based on fiber grating, including following step are provided
Suddenly：
The different fiber grating of centre wavelength is pasted on the side of bull wheel, in the symmetrical position of bull wheel opposite side
The different fiber grating of upper same stickup centre wavelength, and label successively；
Regulation bull wheel produces certain normal force with steamboat at rolling contact point, and makes to produce one between bull wheel and steamboat
The fixed angle of attack, so that bull wheel produces certain cross force at rolling contact point；
The rotating speed of bull wheel is controlled, when bull wheel rotates, the strain signal that bull wheel is produced passes to fiber grating, in (FBG) demodulator
The light source put is transferred in each fiber grating by fiber grating rotary connector, and fiber grating produces strain signal；
Be demodulated for the strain signal of fiber grating by (FBG) demodulator, and demodulated signal is sent into industrial computer, industrial computer pair
Demodulated signal is acquired and is calculating transient state of the bull wheel at rolling contact point just with analysis, the wave length shift according to fiber grating
Pressure and frictional force.
In method of the present invention, 4 fiber gratings are pasted in bull wheel both sides respectively.
In method of the present invention, fiber grating is fixed along bull wheel diametric(al).
Present invention also offers a kind of measurement apparatus of the rolling contact point transient state side-friction coefficient based on fiber grating,
Including steamboat assemble mechanism, bull wheel assemble mechanism, (FBG) demodulator and industrial computer；
The steamboat assemble mechanism includes supporting plate and the steamboat and small wheel assembly that are fixed in the supporting plate, supporting plate
On be fixed with steering wheel, steamboat is by steering wheel and is located at the support of steamboat both sides and fixes on the supporting plate, in small wheel assembly
In the presence of steamboat rotate freely；Angle of attack adjuster is also equipped with the supporting plate, for adjusting at steamboat rolling contact point
Cross force；
The bull wheel assemble mechanism includes the central plane of bull wheel, frequency converter, variable-frequency motor and gear-box, bull wheel and steamboat
At grade, wheel side is tangent；The both sides of bull wheel are symmetrically installed with multiple fiber gratings, and the tail optical fiber of the plurality of fiber grating is equal
By being connected with (FBG) demodulator again after fiber spinning shaft coupling；
The built-in light source of (FBG) demodulator is transferred in each fiber grating by rotary connector, with the rotation of bull wheel, greatly
Wheel is acted in normal force and cross force on bull wheel with the rolling contact point of steamboat, and passes to fiber grating, optical fiber light
Grid produce transient strain force signal；Be demodulated for the transient strain signal of fiber grating by (FBG) demodulator, and demodulated signal is sent
To industrial computer；
Industrial computer, is connected with frequency converter, the rotating speed of the variable-frequency motor for controlling bull wheel, and the industrial computer is additionally operable to receive solution
The demodulated signal for adjusting instrument to send, and be acquired and analyze, the transient state normal force and transient state cross force of fiber grating are calculated, by
This obtains transient state side-friction coefficient of the bull wheel in rolling contact point.
In device of the present invention, the rotary connector is contactless optical fiber connector, is internally provided with optical fiber
Swivel joint, the fibre-optical splice of the fiber grating in one end connection rotation of the optical fiber rotary joint, the optical fiber rotary joint
The other end does not rotate and is connected on (FBG) demodulator by welding wire jumper.
In device of the present invention, 4 fiber gratings are pasted in bull wheel both sides respectively, and 8 fiber gratings weld together,
(FBG) demodulator is accessed by a wire jumper again.
In device of the present invention, fiber grating is encapsulated using fluid sealant.
In device of the present invention, the fluid sealant is epoxide resin AB glue.
The beneficial effect comprise that：It is horizontal the invention provides a kind of rolling contact point transient state based on fiber grating
To the measuring method of coefficient of friction, the different FBG of multiple wavelength is pasted in the symmetric position of bull wheel both sides, in the integer cycle
Interior, the strain Δε at two ends is zero.This addresses the problem cross sensitivity problem, temperature and strain can be simultaneously measured.This measurement
Method can apply to strain the rotating machinery for changing, and especially be good at the occasion that transient changing occurs in strain, for example may be used
To measure rolling body normal strain not in the same time and transverse strain and be contrasted them.
Brief description of the drawings
Below in conjunction with drawings and Examples, the invention will be further described, in accompanying drawing：
Fig. 1 (a) is embodiment of the present invention bull wheel side fiber grating distribution map；
Fig. 1 (b) is embodiment of the present invention bull wheel opposite side fiber grating distribution map；
Fig. 2 is embodiment of the present invention bull wheel force diagram；
Fig. 3 is the local knot of the measurement apparatus of rolling contact point transient state side-friction coefficient of the present invention based on fiber grating
Structure schematic diagram；
Fig. 4 is the side view of embodiment of the present invention bull wheel；
Fig. 5 is embodiment of the present invention bull wheel assemble mechanism structural representation；
Fig. 6 is embodiment of the present invention steamboat assemble mechanism structural representation.
Specific embodiment
In order to make the purpose , technical scheme and advantage of the present invention be clearer, it is right below in conjunction with drawings and Examples
The present invention is further elaborated.It should be appreciated that specific embodiment described herein is only used to explain the present invention, not
For limiting the present invention.
1st, experimental principle
Fiber-optic grating sensor be using bragg wavelength to temperature, strain sensitivity characteristic and be made it is a kind of new
Fibre Optical Sensor.According to the fiber coupling theory of modules, when broadband light is transmitted in fiber grating, Mode Coupling will be produced, met
The light of Bragg condition is reflected, and the center reflection wavelength of Fiber Bragg Grating FBG (FBG) is：
λB=2neff·Λ (1)
In formula, neffIt is the effective refractive index of guided mode, Λ is screen periods.
When wavelength meets Bragg condition formula (1), incident light will be reflected back former road by fiber grating.Differential is taken to it
：
ΔλB=2neff·ΔΛ+2Δneff·Λ (2)
From formula (1), the center reflection wavelength λ of fiber gratingBWith neffWith the change of Λ and change, FBG for strain
All it is sensitive, strain influence λ with temperatureBIt is to be caused by the change of elasto-optical effect and fiber grating periods lambda, temperature influence λB
Then caused by thermo-optic effect and thermal expansion effects.Temperature-strain sensing to fiber grating is measured, Bragg wavelength XsBIt is
The function of temperature T, strain stress, i.e.,
λB=λB(ε,T) (3)
When temperature changes (Δ T), its screen periods is changed because thermal expansion effects extend fiber grating, can
To be expressed as：
In formula, α is the coefficient of expansion of material.For germanium-doped silica fiber, α is taken as 5.5 × 10-7C-1。
On the other hand, because thermo-optic effect makes the refractive index of grating region change, can be expressed as：
In formula, V is the normalized frequency of optical fiber.The optic fiber grating wavelength drift that temperature change causes depends primarily on photo-thermal
Effect, it
95% of thermal drift or so is accounted for, can be expressed as：
In formula, ξ is thermo-optical coeffecient.ξ=6.67 × 10 in silicon fibre-6C-1.Then (5) can be reduced to：
By in above formula (4), (7) substitution (2) formula, the influence for obtaining the drift of temperature on fiber grating wavelength is：
ΔλB(T)=2neffΛ·αΔT+2neffΛ ξ Δ T=λB(α+ξ)ΔT
When extraneous effects of strain is on fiber grating when, fiber grating is on the one hand set to be caused the cycle by mechanical elongation
Λ produces change, can be expressed as：
On the other hand, elasto-optical effect makes fiber grating refractive index change, and can be expressed as：
To above formula (9) two ends simultaneously divided by nffCan obtain：
In formula, P1j(j=1,2) is pockel coefficients, and ν is Poisson's ratio, defines valid elastic-optic constants Pe：
Then above formula (10) can be converted into：
By in above formula (8), (12) substitution (2) formula, the influence for obtaining straining to optic fiber grating wavelength drift is：
ΔλB(ε)=2neffΛ·Δε-2neffΛ Pe Δs ε=λB(1-Pe)Δε
Due to the center reflection wavelength λ of fiber gratingBIt is neffWith the function of Λ, λBWith neffChange with the change of Λ, therefore
FBG is sensitive for strain and temperature, so the drift of fiber grating center reflection wavelength is common by temperature and strain
Influence, then can be expressed as：
ΔλB=λB(α+ξ)ΔT+λB(1-Pe)Δε
Known temperature sensitivity coefficient KTWith ga(u)ge factor KεCan be expressed as：
The then variation delta λ of fiber grating center reflection wavelengthΒWith temperature variation Δ Τ and the pass of strain variation amount Δ ε
System is represented by：
ΔλB=KTΔT+KεΔε
In formula, KTIt is temperature control coefficient, can be tested by temperature calibration and measured；KεIt is ga(u)ge factor, can
Measured with by straining calibration experiment.
When fiber grating is used for sensing measurement, the change of bragg wavelength can be all caused due to strain and temperature, it is single
Fiber Bragg Grating FBG cannot tell the change of the bragg wavelength that strain and temperature cause respectively in itself, so as to cannot realize
Accurate measurement.Solve the thought that this problem is all based on greatly dual-wavelength fiber grating matrix operation method.
Use for reference dual-wavelength fiber grating matrix operation method, using bull wheel tow sides be arranged symmetrically 2 fiber gratings come
Realize eliminating the influence that temperature band is come.Because two fiber gratings are under a mutually synthermal environment, they are with temperature
Change is identical, and their temperature is raised simultaneously when the temperature increases, and their temperature is reduced simultaneously when the temperature decreases, and
When element stress, because fiber grating is on tow sides, so a fiber grating tension, centre wavelength increases, another
Individual fiber grating is pressurized, and centre wavelength reduces.So their strain measurement is worth to highlight.So, method ten is used using this
Divide reliable effective.
It can be seen from above formula, 2 fiber gratings being pasted onto in same temperature environment are influenceed phase by temperature effect
Together, for monitor strain grating phase wavelength drift subtract as caused by temperature change centre wavelength drift can be obtained by by
The caused wave length shift of measured object strain, so as to obtain the strain value of current measured object.Temperature is eliminated by this method to surveying
The influence measured one's own ability, following scheme has also used the method.
In sum, shown in final scheme schematic diagram such as Fig. 1 (a) and Fig. 1 (b)：
Fiber grating can also greatly reduce influence of the temperature to wavelength and be answered so as to prominent with the mounting method of this radial direction
Become the influence to wavelength, because experiment needs to measure the strain of Wheel/Rail Contact Point, fiber grating should be pasted as far as possible
In improving certainty of measurement near the place of wheel, and the one side of wheel sticks four also for the precision for improving measurement.
2nd, experimental program
It is respectively normal force (i.e. normal pressure) and cross force (i.e. frictional force) in this experiment, it is necessary to measure two power,
This first sketches two generation principles of power, and marks their action direction, as shown in Figure 2.
Normal force (i.e. normal pressure)：Simulation train is when travelling in orbit, train because of the gravity-pressing wheel track of itself, so
Normal force is directed to the applying of the bull wheel center of circle.Steamboat analog orbit is used, then normal force can be forced by steamboat applying pretension
Tight bull wheel realized, the normal force on bull wheel is set into 1000N.
Cross force (i.e. frictional force)：In train when turning, because the presence of friction factor, then train is received for simulation
To a frictional force, this power is called cross force by we, and direction is perpendicular to big wheel surface.Cross force be being continually changing,
But teacher Liu points out numerical value no more than 250N, and we can produce cross force by changing the angle of attack of two-wheeled, by bull wheel
Cross force be set to 200N.
The structural model figure of integral experiment platform as indicated at 3, the rolling contact point transient state side-friction system based on fiber grating
Several measurement apparatus, including steamboat assemble mechanism 100, bull wheel assemble mechanism 200, (FBG) demodulator and industrial computer；
The steamboat assemble mechanism includes supporting plate and the steamboat and small wheel assembly that are fixed in the supporting plate, supporting plate
On be fixed with steering wheel, steamboat is by steering wheel and is located at the support of steamboat both sides and fixes on the supporting plate, in small wheel assembly
In the presence of steamboat rotate freely；Angle of attack adjuster is also equipped with the supporting plate, for adjusting at steamboat rolling contact point
Cross force；
As shown in fig. 6, in one embodiment of the present of invention, steamboat assemble mechanism mainly includes steamboat 21, expansion sleeve 22, small
It is wheel rotating shaft 23, bearing 24, support 25, steering wheel 26, front end panel 27, gear wheel 28, worm gear 29, little gear 30, worm screw 31, big
Gear shaft, pinion shaft, rear bearing sheet 32, bolt, nut etc..Wherein, steamboat is mainly used to simulate train wheel track, and expansion sleeve
Because accuracy of alignment is good, install, dismounting facility, therefore utilize the effect of the stress bolt of high intensity, in the inner ring of expansion sleeve and small
Between wheel rotating shaft, produce enclasping force between the outer shroud of expansion sleeve and steamboat wheel hub, and then realize the connection of steamboat and steamboat rotating shaft,
Angular contact ball bearing is used to support steamboat rotating shaft and steamboat, reduces the coefficient of friction in rotary course and ensures its rotating accuracy,
Therefore the inner ring of angular contact ball bearing and steamboat rotating shaft, outer ring is connected with support using interference fits, because steamboat utilizes swelling
Set is arranged in steamboat rotating shaft, therefore steamboat rotating shaft is used to bear moment of flexure and torque of the steamboat in rotation work, and support is using small
Take turns rotating shaft to support steamboat, cradle bottom surface is connected and fastened on the steering wheel with bolt, turn into steamboat, support, steering wheel
One entirety, therefore can be by the angle of attack that changes the anglec of rotation of steering wheel to adjust between steamboat and bull wheel；By large and small gear shaft
It is installed on front end panel, then steering wheel and worm gear are respectively installed on large and small gear shaft from the preceding surface of front end panel are used in combination
Nut screwing clamping, and surface is respectively installed on large and small gear shaft (now large and small gear phase from after front end panel by large and small gear
Mutually engage and torque can be transmitted) and nut screwing clamping is used, worm screw is arranged at front end panel worm gear lower section makes worm and wheel
Back and front supporting plate screw bolt and nut is finally connected and is fastened on experimental bench by engagement to transmit torque, and in forward and backward branch
Force bolt and force nut are installed between fagging.When using instrument rotary worm, snail is caused because worm and wheel is engaged
Wheel rotation, and worm and wheel presses 1:60 transmission, worm gear by pinion shaft drive little gear rotation, due to little gear with it is big
Gear is engaged and causes gear wheel rotation, and little gear presses 1 with gear wheel:6 transmissions, gear wheel is driven by Large Gear Shaft and turned to
Disc spins, because steamboat is fixed on the steering wheel by expansion sleeve, steamboat rotating shaft, bearing and support, make steamboat and turn to dish type
Into an entirety, therefore steamboat rotates together with steering wheel, makes to form certain angle of attack between steamboat and bull wheel, and because torque exists
Total gearratio is 1 in transmittance process:360, therefore when (i.e. 360 °) are turned around in worm screw rotation, steamboat rotates 1 ° when being transferred to steamboat
And make to form 1 ° of angle of attack between steamboat and bull wheel.
As shown in figure 5, bull wheel assemble mechanism includes bull wheel, frequency converter, variable-frequency motor and gear-box, in bull wheel and steamboat
At grade, wheel side is tangent for heart plane；The both sides of bull wheel are symmetrically installed with multiple fiber gratings, the plurality of fiber grating
Tail optical fiber with (FBG) demodulator by being connected again after fiber spinning shaft coupling；
The built-in light source of (FBG) demodulator is transferred in each fiber grating by rotary connector, with the rotation of bull wheel, greatly
Wheel is acted in normal force and cross force on bull wheel with the rolling contact point of steamboat, and passes to fiber grating, optical fiber light
Grid produce transient strain force signal；Be demodulated for the transient strain signal of fiber grating by (FBG) demodulator, and demodulated signal is sent
To industrial computer；
Industrial computer, is connected with frequency converter, the rotating speed of the variable-frequency motor for controlling bull wheel, and the industrial computer is additionally operable to receive solution
The demodulated signal for adjusting instrument to send, and be acquired and analyze, the transient state normal force and transient state cross force of fiber grating are calculated, thus
Obtain transient state side-friction coefficient of the bull wheel in rolling contact point.
The rotary connector is contactless optical fiber connector, is internally provided with optical fiber rotary joint, the fiber spinning
The fibre-optical splice of the fiber grating in one end connection rotation of joint, the other end of the optical fiber rotary joint does not rotate and by weldering
Wire jumper is connect to be connected on (FBG) demodulator.
Normal force and cross force due to bull wheel in rolling contact point are all directly acted on bull wheel, it is possible to which design exists
Fiber grating is directly pasted on bull wheel, as shown in Fig. 1 (a), Fig. 1 (b) and Fig. 4, by the transient strain of detection fiber grating
To measure transient state normal force and transient state cross force, thus transient state side-friction system of the bull wheel in rolling contact point can be obtained
Number.
1) normal force measurement：After the completion of the overall assembling with bull wheel of steamboat, steamboat is set to apply bull wheel by screwing bolts
One size is the power of 1000N, as normal force.When bull wheel is subject to normal force, bull wheel can produce compressive strain due to being pressurized, therefore
In bull wheel while pasting 4 Fiber Bragg Grating FBGs, but requirement is symmetrical two-by-two, and when being pressurized for wherein 1, another 3 are in nature shape
State, is contrasted.Because the state that bull wheel is pressurized is only in the contact point of bull wheel and steamboat, so only 1 grating state change,
By the grating on its opposite as a comparison, the value for solving normal force is measured.
2) cross force measurement：After the completion of the overall assembling with bull wheel of steamboat, screwing bolts make to produce the method for 1000N on bull wheel
Xiang Li, then worm screw turns an angle makes to form certain angle of attack between bull wheel and steamboat, now, not only can between them
Normal force is produced, while also having a horizontal creep, horizontal creep power, as cross force is produced.When bull wheel is subject to cross force
When, the one side of bull wheel understands tension and produces stretching strain, and another side can be pressurized and produce compressive strain, therefore symmetrical in bull wheel tow sides
4 groups of Fiber Bragg Grating FBGs are pasted, but is required symmetrical two-by-two and is uniformly distributed, certain the fiber grating tension wherein on front is produced
Raw stretching strain, and another fiber grating symmetrical therewith on reverse side is pressurized and produces compressive strain, is contrasted.Because bull wheel is by horizontal stroke
To the state of power at the contact point of bull wheel and steamboat, so the state of only one group of fiber grating changes, by the group
Two symmetrical fiber gratings are compared, and measure the value for obtaining normal force.
Based on said apparatus, the measurement side of rolling contact point transient state side-friction coefficient of the present invention based on fiber grating
Method, specifically includes following steps：
S1, the side that the different fiber grating of centre wavelength is pasted on bull wheel, in the symmetrical of bull wheel opposite side
It is same on position to paste the different fiber grating of centre wavelength, and label successively；
S2, regulation bull wheel and steamboat produce certain normal force at rolling contact point, and make to be produced between bull wheel and steamboat
The certain angle of attack of life, so that bull wheel produces certain cross force at rolling contact point；
The rotating speed of S3, control bull wheel, when bull wheel rotates, the strain signal that bull wheel is produced passes to fiber grating, demodulates
The built-in light source of instrument is transferred in each fiber grating by fiber grating rotary connector, and fiber grating produces strain signal；
Be demodulated for the strain signal of fiber grating by S4, (FBG) demodulator, and demodulated signal is sent into industrial computer, industrial computer
Demodulated signal is acquired and calculates transient state of the bull wheel at rolling contact point with analysis, the wave length shift according to fiber grating
Normal pressure and frictional force.
3rd, experiment content
The sensitivity coefficient of Fiber Bragg Grating FBG is determined, if the sensitivity coefficient influence of fiber grating is less or can
With by identical in formula eliminating deformation formula (strain or temperature) sensitivity coefficient, you can sensitivity is not demarcated, at this
To eliminate temperature and Strain-coupled problem in experiment, so sensitivity coefficient must be re-scaled.
This experiment carries out strain measurement using fiber Bragg grating sensor.By experimental program, in this experiment
In, it is necessary to first making a kind of fiber-optic grating sensor carries out strain calibration experiment, to measure the strain spirit of fiber-optic grating sensor
Quick coefficient.Then, then make another fiber-optic grating sensor carry out the strain measurement of testing stand contact point experiment, to measure wheel track
Strain of the bull wheel at contact point on testing stand, so needing to carry out two groups of experiments respectively.
3.1st, calibration experiment is strained
In order to obtain ga(u)ge factor, decision uses control variate method, first makes number of the temperature necessarily i.e. behind formula
Value is certain, then changes the strain behind formula, while measuring the data of centre wavelength drift, carries out statistics using public
Formula calculates the ga(u)ge factor of Fiber Bragg Grating FBG.
Be obtain fiber Bragg grating sensor strain measurement precision, use dynamometer complete the coefficient of strain demarcate with
And control experiment, to study under different loads, centre wavelength drift is continuously applied to power on the element for post fiber grating,
Centre wavelength is drawn after (FBG) demodulator measurement after its numerical stability, dynamometer reads the size of power.
3.2nd, the measurement of correlation of normal force (normal pressure)
After the completion of experimental bench assembling, the integral installation of bull wheel and steamboat is completed, then installed additional between bull wheel and steamboat
Dynamometer.It is bolt force application apparatus at the rear of steamboat, makes to produce normal force between bull wheel and steamboat by swivel bolt, not
Disconnected screwing bolts make normal force gradually increase until reaching 1000N (being determined by the dynamometer between bull wheel and steamboat), while
Record the wavelength data of now fiber grating.
Detailed process：
1) by 8 different fiber gratings of centre wavelength from 1~8 label successively, and the welding that joins end to end in order
Together, wherein, No. 8 other ends of fiber grating are connected and weld together with wire jumper.Then viscose glue is used by fiber grating
It is pasted onto on the position corresponding with label of bull wheel both sides.Test error can be prevented using eight fiber gratings, and eliminates temperature
The influence of coupling is spent, is pasted shown in such as Fig. 1 (a) of the bull wheel after fiber grating and Fig. 1 (b)；
2) unscrew anchor nut and extract foundation bolt out, will support steamboat assembly be moved rearwards by a lattice, make bull wheel with
Length of the gap slightly larger than dynamometer between steamboat, the position of adjustment assembly body makes bull wheel be alignd with steamboat, inserts footing spiral shell
Bolt simultaneously screws anchor nut, and the assembly of steamboat will be supported to be fixed on testing stand；
3) dynamometer is placed between bull wheel and steamboat, then screwing bolts make bull wheel clamp dynamometer (survey with steamboat
Power meter two ends are fitted without draw ring).Dynamometer is coupled together with display again and display switches on power.Finally adjust aobvious
Show the range (operating process that can be gone up to specifications is carried out) of the scaling position of device, the instrument unit of display, and measurement.
Confirm by origin after adjustment is suitable.Now, the pressure (normal direction i.e. between bull wheel and steamboat being subject to will be shown on display
Power)；
4) tail optical fiber of wire jumper is inserted the connectivity port of (FBG) demodulator, then (FBG) demodulator is connected with computer by netting twine, then
General supply and opening display power supply are opened, starts computer sensing testing software.The point under the menu of computer sensing software
Connection is hit, connection (FBG) demodulator is transmitted with Computer signal, after display successful connection, set gradually sample frequency (for 4KHz), lead to
Road and gain (being 79 to the maximum).Click starts measurement, and software will show the data obtained by (FBG) demodulator, while having record to protect
Deposit function (each second can preserve 4000 data), you can complete the collection and preservation of data；
5) bolt in screwing bolts force application apparatus, makes the normal force between bull wheel and steamboat gradually increase, and works as display
When above for 1000N (normal force between bull wheel and steamboat is 1000N), stop screwing bolts, while recording now optical fiber
The wavelength data of grating.
3.3rd, the measurement of correlation of cross force (frictional force)
According to the experimental provision of above-mentioned experiment, first dynamometer is taken off between bull wheel and steamboat, then steamboat will be supported
Assembly integrally removed from experimental bench, then apply the transverse direction of 200N at the rolling contact point of bull wheel by dynamometer
Power, while recording the wavelength data of now fiber grating.
Detailed process：
1) bolt of bolt force application apparatus is unscrewed, dynamometer is taken off between bull wheel and steamboat；
2) unscrew anchor nut and extract foundation bolt out, the assembly of steamboat will be supported integrally to be removed from experimental bench；
3) screw on and tighten the draw ring at dynamometer two ends, at the rolling contact point on the draw ring of dynamometer one end and bull wheel
(i.e. when bull wheel is contacted with steamboat, position of the two-wheeled contact point on bull wheel) (cord can bear more than 200N's by cord
Pulling force) couple together, then a cord will be also connected on the draw ring of the dynamometer other end, finally apply one in the free end of cord
Fixed pulling force；
4) dynamometer is coupled together with display and display switches on power.Finally adjust the decimal point position of display
Put, the instrument unit of display, and the range for measuring (operating process that can be gone up to specifications is carried out).By original after adjustment is suitable
Point confirmation, will now, on display show the pressure (normal force i.e. between bull wheel and steamboat) being subject to；
5) tail optical fiber of wire jumper is inserted the connectivity port of (FBG) demodulator, then (FBG) demodulator is connected with computer by netting twine, then
General supply and opening display power supply are opened, starts computer sensing testing software.The point under the menu of computer sensing software
Connection is hit, connection (FBG) demodulator is transmitted with Computer signal, after display successful connection, set gradually sample frequency (for 4KHz), lead to
Road and gain (being 79 to the maximum).Click starts measurement, and software will show the data obtained by (FBG) demodulator, while having record to protect
Deposit function (each second can preserve 4000 data), you can complete the collection and preservation of data；
6) the continuous pulling force of increase cord free end, makes the cross force suffered by bull wheel gradually increase, when being on display
During 200N (cross force between bull wheel and steamboat is 200N), the pulling force of increase cord free end is stopped immediately and the drawing is kept
Power is constant, while recording the wavelength data of now fiber grating.
3.4th, the measurement of rolling contact point transient state normal force (normal pressure) and cross force (frictional force)
According to the experimental provision of above-mentioned experiment, the assembly of steamboat will be supported to be arranged on experimental bench.Exerted a force by bolt
Device makes to produce the normal force of 1000N between bull wheel and steamboat, makes to form certain punching between bull wheel and steamboat by rotary worm
Angle and produce the cross force of 200N, wire jumper is connected on (FBG) demodulator through the contactless joints of optical fibre, control bull wheel becomes
Frequency motor makees constant speed rotary, such as 100r/min with a certain suitable rotating speed, and the strain signal of fiber grating is adopted with (FBG) demodulator
Collect and save, processed the data obtained and calculated rolling contact point transient state normal force (normal pressure) and cross force
(frictional force), then be that can obtain transient state side-friction coefficient by formula.
In this experiment, because testing stand bull wheel needs to rotate, therefore fiber grating after encapsulating on the bull wheel can not be straight
It is connected on (FBG) demodulator in succession, because the rotation of bull wheel can drive the rotation of optical patchcord if being directly connected to, so as to cause wiring
Head cannot be fixed.To solve this problem, connection line of optic fibre is filled in shaft coupling, pulled out from right side and welded.
Optical fiber junction is a kind of contactless joints of optical fibre, is an optical fiber rotary joint, its one inside it
Fibre-optical splice in the connection rotation of end, the fibre-optical splice of the other end is non-rotary, therefore can be welded from non-rotary this end
Wire jumper is connected on (FBG) demodulator, so just solves above mentioned problem.
Detailed process：
1) assembly of steamboat will be supported to place in situ to go up, then loads onto foundation bolt and tighten anchor nut,
The assembly of support steamboat is fixed on testing stand；
2) wire jumper is passed through the contactless joints of optical fibre, then the tail optical fiber of wire jumper is inserted the connectivity port of (FBG) demodulator,
(FBG) demodulator is connected with computer by netting twine, general supply and opening display power supply is then opened, starts computer sensing testing
Software.Connection is clicked under the menu of computer sensing software, (FBG) demodulator is connected and is transmitted with Computer signal, show successful connection
Afterwards, sample frequency (for 4KHz), passage and gain (being 79 to the maximum) are set gradually.Click starts measurement, and software will show solution
The data obtained by instrument are adjusted, while having record to preserve function (each second can preserve 4000 data), you can complete data
Collection and preservation；
3) bolt constantly in screwing bolts force application apparatus, makes steamboat gradually increase the pretightning force that bull wheel applies, in rotation
During tight, when the wavelength data of fiber grating is consistent with the wavelength data in 3.2 experiments in (FBG) demodulator, stopping screws spiral shell
Bolt, illustrates that the normal force now between bull wheel and steamboat reaches 1000N；
4) toward the direction (clockwise or counterclockwise) constantly rotary worm so that between bull wheel and steamboat
The angle of attack constantly increases, so as to cause cross force between bull wheel and steamboat gradually to increase, in rotary course, when optical fiber in (FBG) demodulator
When the wavelength data of grating is consistent with the wavelength data in 3.3 experiments, stop the rotation worm screw, illustrates now between bull wheel and steamboat
Cross force reach 200N.Shut down computer sensing testing software；
5) electronic box of controlled motor is opened, master switch gets on, by combined floodgates/separating brake switch clockwise torsion (i.e. opening
Pass is screwed on combined floodgate), (KingView is for controlling variable-frequency motor to run shape on industrial computer to " KingView " software on opening computer
The software of state, by directly setting the drive manner of variable-frequency motor, such as square wave, triangular wave, sine wave, constant speed on the software,
The speed of service, wavelength and amplitude come control variable-frequency motor according in scheme state run), click on " RUN ", open the control
The parameter setting interface of software, sets bull wheel with constant speed rotary, and rotary speed is set as 100r/min, and amplitude and cycle all set
It is 0, clicks on " parameter confirmation ", press the green start button of electronic box, motor is rotated and drives bull wheel with 100r/ by gear-box
The rotating speed constant speed rotary of min；
6) after bull wheel constant revolution, computer sensing testing software is started.The point under the menu of computer sensing software
Hit " connection ", connect (FBG) demodulator and Computer signal and transmit, after display successful connection, set gradually sample frequency (for 4KHz),
Passage and gain (being 79 to the maximum).Click starts measurement, and software will show the number of the optic fiber grating wavelength obtained by (FBG) demodulator
According to, preserve function (each second can preserve 4000 data) while having and recording, that is, complete the collection and preservation of experimental data.
According to the measurement experiment of above rolling contact point transient state normal force (normal pressure) and cross force (frictional force), by gained
Wavelength data to fiber grating is analyzed, processes, and the wave length shift according to fiber grating calculates bull wheel and is being in rolling contact
Transient state normal pressure and frictional force at point.Because coefficient of friction is the ratio of frictional force and normal pressure, then can be calculated by formula
Go out transient state side-friction coefficient of the bull wheel in rolling contact point.
It should be appreciated that for those of ordinary skills, can according to the above description be improved or converted,
And all these modifications and variations should all belong to the protection domain of appended claims of the present invention.
Claims (8)
1. a kind of measuring method of the rolling contact point transient state side-friction coefficient based on fiber grating, it is characterised in that including
Following steps：
The different fiber grating of centre wavelength is pasted on the side of bull wheel, it is same on the symmetrical position of bull wheel opposite side
Sample pastes the different fiber grating of centre wavelength, and label successively；
Regulation bull wheel and steamboat produce certain normal force at rolling contact point, and make to be produced between bull wheel and steamboat certain
The angle of attack, so that bull wheel produces certain cross force at rolling contact point；
The built-in light source of (FBG) demodulator is transferred in each fiber grating by fiber grating rotary connector, controls turning for bull wheel
Speed, when bull wheel rotates, the strain signal that bull wheel is produced passes to fiber grating, and fiber grating produces strain signal；
Be demodulated for the strain signal of fiber grating by (FBG) demodulator, and demodulated signal is sent into industrial computer, and industrial computer is to demodulation
Signal is acquired and calculates transient state normal pressure of the bull wheel at rolling contact point with analysis, the wave length shift according to fiber grating
With frictional force.
2. method according to claim 1, it is characterised in that paste 4 fiber gratings respectively in bull wheel both sides.
3. method according to claim 1, it is characterised in that fiber grating is fixed along bull wheel diametric(al).
4. a kind of measurement apparatus of the rolling contact point transient state side-friction coefficient based on fiber grating, it is characterised in that including
Steamboat assemble mechanism, bull wheel assemble mechanism, (FBG) demodulator and industrial computer；
The steamboat assemble mechanism includes supporting plate and the steamboat and small wheel assembly that are fixed in the supporting plate, solid in supporting plate
Surely there is a steering wheel, steamboat is by steering wheel and is located at the support of steamboat both sides and fixes on the supporting plate, in the work of small wheel assembly
Rotated freely with lower steamboat；Angle of attack adjuster is also equipped with the supporting plate, for adjusting the transverse direction at steamboat rolling contact point
Power；
The bull wheel assemble mechanism includes bull wheel, frequency converter, variable-frequency motor and gear-box, and the central plane of bull wheel and steamboat is same
In one plane, wheel side is tangent；The both sides of bull wheel are symmetrically installed with multiple fiber gratings, and the tail optical fiber of the plurality of fiber grating passes through
It is connected with (FBG) demodulator again after fiber spinning shaft coupling；
The built-in light source of (FBG) demodulator is transferred in each fiber grating by rotary connector, with the rotation of bull wheel, bull wheel with
The rolling contact point of steamboat is acted in normal force and cross force on bull wheel, and passes to fiber grating, and fiber grating is produced
Raw transient strain force signal；Be demodulated for the transient strain signal of fiber grating by (FBG) demodulator, and demodulated signal is sent into work
Control machine；
Industrial computer, is connected with frequency converter, the rotating speed of the variable-frequency motor for controlling bull wheel, and the industrial computer is additionally operable to receive (FBG) demodulator
The demodulated signal of transmission, and be acquired and analyze, the transient state normal force and transient state cross force of fiber grating are calculated, thus obtain
Transient state side-friction coefficient of the bull wheel in rolling contact point.
5. device according to claim 4, it is characterised in that the rotary connector is contactless optical fiber connector,
Optical fiber rotary joint is internally provided with, the fibre-optical splice of the fiber grating in one end connection rotation of the optical fiber rotary joint should
The other end of optical fiber rotary joint does not rotate and is connected on (FBG) demodulator by welding wire jumper.
6. device according to claim 4, it is characterised in that paste 4 fiber gratings, 8 optical fiber respectively in bull wheel both sides
Grating welds together, then accesses (FBG) demodulator by a wire jumper.
7. device according to claim 4, it is characterised in that fiber grating is encapsulated using fluid sealant.
8. device according to claim 7, it is characterised in that the fluid sealant is epoxide resin AB glue.
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