CN106769840B - The measurement method of rolling contact point transient state side-friction coefficient based on fiber grating - Google Patents
The measurement method of rolling contact point transient state side-friction coefficient based on fiber grating Download PDFInfo
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- CN106769840B CN106769840B CN201610820853.9A CN201610820853A CN106769840B CN 106769840 B CN106769840 B CN 106769840B CN 201610820853 A CN201610820853 A CN 201610820853A CN 106769840 B CN106769840 B CN 106769840B
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- G01N19/02—Measuring coefficient of friction between materials
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Abstract
The measurement method of the invention discloses a kind of rolling contact point transient state side-friction coefficient based on fiber grating, comprising the following steps: the different fiber grating of central wavelength is symmetrically pasted on to the two sides of bull wheel, and successively label；It adjusts bull wheel and steamboat generates certain normal force at rolling contact point, and make to generate certain angle of attack between bull wheel and steamboat, so that bull wheel generates certain cross force at rolling contact point；The revolving speed for controlling bull wheel, when bull wheel rotation, the strain signal that bull wheel generates passes to fiber grating, and the light source built in (FBG) demodulator is transferred in each fiber grating by fiber grating rotary connector, and fiber grating generates strain signal；(FBG) demodulator demodulates the strain signal of fiber grating, and demodulated signal is sent to industrial personal computer, and industrial personal computer is acquired and analyzes to demodulated signal, calculates transient state normal pressure and frictional force of the bull wheel at rolling contact point according to the wave length shift of fiber grating.
Description
Technical field
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 are horizontal
To the measurement method and device of coefficient of friction.
Background technique
Fiber grating sensing technology is grown up on the basis of optical fiber sensing technology, fiber grating sensing system base
Present principles are that multiple gratings (respectively having different central wavelength), the light wave issued by wideband light source have been concatenated on an optical fiber
By splitter by all gratings, another the interface coupled into optical fibres grating demodulation instrument of reflected light through splitter leads to
Fiber Bragg grating (FBG) demodulator is crossed to measure the wavelength of reflected light and its variation, so that it may solution adjusting data is obtained, using point of data
Analysis and processing, so that it may obtain corresponding to the variable quantity of environment at each fiber grating, such as temperature, stress.It is 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, be able to achieve real-time online, absolute number formula measurement, have measurement range is wide, precision is high, 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 high confidence level provide ideal 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 constantly improve for fiber grating manufacturing technology, the increasingly extension of application field, light
Fine grating has become at present one of the fiber optic passive device of most development prospect.Fiber bragg grating (FBG) is at present in light
Most gratings in fibre sensing, and cross sensitivity problem is the protrusion for restricting fiber-optic grating sensor and further developing
Problem.In optical fiber grating sensing practical application, since grating Bragg wavelength is all sensitive, i.e. optical fiber to strain and temperature
There is strains, Temperature cross-over tender subject for grating sensor, when fiber grating is used for sensing measurement, single optical fiber Bragg
The change of bragg wavelength caused by grating itself can not tell strain and temperature respectively, and then cannot achieve accurate survey
Amount.
Summary of the invention
The technical problem to be solved in the present invention is that can not divide for single fiber bragg grating itself in the prior art
The change of bragg wavelength caused by discerning strain and temperature respectively provides one kind to cannot achieve the defect of precise measurement
The measurement method and device of the rolling contact point transient state side-friction coefficient based on fiber grating of precise measurement may be implemented.
The technical solution adopted by the present invention to solve the technical problems is:
A kind of measurement method of rolling contact point transient state side-friction coefficient based on fiber grating, including following step are provided
It is rapid:
The different fiber grating of central wavelength is pasted on to the side of bull wheel, in the symmetrical position of the bull wheel other side
The different fiber grating of upper same stickup central wavelength, and successively label；
It adjusts bull wheel and steamboat generates certain normal force at rolling contact point, and make to generate one between bull wheel and steamboat
The fixed angle of attack, so that bull wheel generates certain cross force at rolling contact point；
The revolving speed for controlling bull wheel, when bull wheel rotation, the strain signal that bull wheel generates passes to fiber grating, in (FBG) demodulator
The light source set is transferred in each fiber grating by fiber grating rotary connector, and fiber grating generates strain signal；
(FBG) demodulator demodulates the strain signal of fiber grating, and demodulated signal is sent to industrial personal computer, industrial personal computer pair
Demodulated signal is acquired and analyzes, and is calculating transient state of the bull wheel at rolling contact point just according to the wave length shift of fiber grating
Pressure and frictional force.
In method of the present invention, 4 fiber gratings are pasted in bull wheel two sides respectively.
In method of the present invention, fiber grating is fixed along bull wheel diametrical direction.
The measuring device of the present invention also provides a kind of rolling contact point transient state side-friction coefficient based on fiber grating,
Including steamboat assemble mechanism, bull wheel assemble mechanism, (FBG) demodulator and industrial personal computer；
The steamboat assemble mechanism includes support plate and the steamboat being fixed in the support plate and small wheel assembly, support plate
On be fixed with steering wheel, steamboat by steering wheel and be located at steamboat two sides bracket it is fixed on the supporting plate, in small wheel assembly
Under the action of steamboat rotate freely；Angle of attack adjuster is also equipped in the support plate, for adjusting at steamboat rolling contact point
Cross force；
The bull wheel assemble mechanism includes bull wheel, frequency converter, variable-frequency motor and gear-box, the central plane of bull wheel and steamboat
In the same plane, wheel side is tangent；The two sides of bull wheel are symmetrically installed with multiple fiber gratings, and the tail optical fiber of multiple fiber grating is equal
By being connect again with (FBG) demodulator after fiber spinning shaft coupling；
Light source built in (FBG) demodulator is transferred in each fiber grating by rotary connector, with the rotation of bull wheel, greatly
The rolling contact point of wheel and steamboat generates the normal force and cross force acted on bull wheel, and passes to fiber grating, optical fiber light
Grid generate transient strain force signal；(FBG) demodulator demodulates the transient strain signal of fiber grating, and demodulated signal is sent
To industrial personal computer；
Industrial personal computer is connect with frequency converter, and the revolving speed of the variable-frequency motor for controlling bull wheel, the industrial personal computer is also used 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
Bull wheel is found out in the transient state side-friction coefficient of rolling contact point.
In device of the present invention, the rotary connector is contactless optical fiber connector, is internally provided with optical fiber
Rotary joint, one end of the optical fiber rotary joint connect the fibre-optical splice of the fiber grating in rotation, the optical fiber rotary joint
The other end is not rotated and is connected on (FBG) demodulator by welding wire jumper.
In device of the present invention, 4 fiber gratings are pasted in bull wheel two 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 sealant.
In device of the present invention, the sealant is epoxy resin AB glue.
The beneficial effect comprise that: the present invention provides a kind of, and the rolling contact point transient state based on fiber grating is horizontal
To the measurement method of coefficient of friction, the different FBG of multiple wavelength is pasted in the symmetric position of bull wheel two sides, in the integer period
Interior, the strain Δε at both ends is zero.This addresses the problem cross sensitivity problems, can measure temperature and strain simultaneously.This measurement
Method can be applied to strain changed rotating machinery, is especially good at and the occasion of transient changing occurs in strain, such as can
To measure the normal strain of rolling body different moments and transverse strain and compare them.
Detailed description of the invention
Present invention will be further explained below with reference to the attached drawings and examples, in attached drawing:
Fig. 1 (a) is bull wheel of embodiment of the present invention side fiber grating distribution map；
Fig. 1 (b) is bull wheel of embodiment of the present invention other side fiber grating distribution map；
Fig. 2 is bull wheel force diagram of the embodiment of the present invention；
Fig. 3 is the part knot of the measuring device of the rolling contact point transient state side-friction coefficient the present invention is based on fiber grating
Structure schematic diagram；
Fig. 4 is the side view of bull wheel of the embodiment of the present invention；
Fig. 5 is bull wheel of embodiment of the present invention assemble mechanism structural schematic diagram；
Fig. 6 is steamboat of embodiment of the present invention assemble mechanism structural schematic diagram.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that described herein, specific examples are only used to explain the present invention, not
For limiting the present invention.
1, experimental principle
Fiber-optic grating sensor be using bragg wavelength to temperature, the sensitivity characteristic of strain and manufactured one kind is novel
Fibre optical sensor.According to the fiber coupling theory of modules, when broadband light is transmitted in fiber grating, Mode Coupling will be generated, is met
The light of Bragg condition is reflected, the center reflection wavelength of fiber bragg grating (FBG) are as follows:
λB=2neff·Λ (1)
In formula, neffFor 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)
By formula (1) it is found that the center reflection wavelength λ of fiber gratingBWith neffChange with Λ and change, FBG is for strain
It is all sensitive, strain influence λ with temperatureBCaused by being the variation as elasto-optical effect and fiber grating periods lambda, temperature influences λB
It is then as caused by thermo-optic effect and thermal expansion effects.Temperature-strain sensing measurement to fiber grating, Bragg wavelength XBIt is
The function of temperature T, strain stress, i.e.,
λB=λB(ε,T) (3)
When temperature changes (Δ T), change its screen periods since thermal expansion effects extend fiber grating, it can
To indicate are as follows:
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, it since thermo-optic effect makes the refractive index of grating region change, can indicate are as follows:
In formula, V is the normalized frequency of optical fiber.The drift of optic fiber grating wavelength caused by temperature change depends primarily on photo-thermal
Effect, it
95% or so of thermal drift is accounted for, can be indicated are as follows:
In formula, ξ is thermo-optical coeffecient.ξ=6.67 × 10 in silicon fibre-6C-1.Then (5) can simplify are as follows:
Above formula (4), (7) are substituted into (2) formula, the influence of temperature on fiber grating wavelength drift is obtained are as follows:
ΔλB(T)=2neffΛ·αΔT+2neffΛ ξ Δ T=λB(α+ξ)ΔT
When extraneous effects of strain is when on fiber grating, fiber grating is on the one hand made to lead to the period by mechanical elongation
Λ generates variation, can indicate are as follows:
On the other hand, elasto-optical effect makes fiber grating refractive index change, and can indicate are as follows:
To above formula (9) both ends simultaneously divided by neffIt can obtain:
In formula, P1j(j=1,2) is pockel coefficient, and ν is Poisson's ratio, defines valid elastic-optic constants Pe:
Then above formula (10) can convert are as follows:
Above formula (8), (12) are substituted into (2) formula, obtain straining the influence to optic fiber grating wavelength drift are as follows:
ΔλB(ε)=2neffΛ·Δε-2neffΛ Pe Δ ε=λB(1-Pe)Δε
Due to the center reflection wavelength λ of fiber gratingBIt is neffWith the function of Λ, λBWith neffChange with Λ and change, therefore
FBG is sensitive for strain and temperature, so the drift of fiber grating center reflection wavelength is by temperature and to strain common
It influences, then can indicate are as follows:
ΔλB=λB(α+ξ)ΔT+λB(1-Pe)Δε
Known temperature sensitivity coefficient KTWith ga(u)ge factor KεIt can respectively indicate are as follows:
The then variation delta λ of fiber grating center reflection wavelengthΒWith the pass of temperature variation Δ T and strain variation amount Δ ε
System may be expressed as:
ΔλB=KTΔT+KεΔε
In formula, KTFor temperature sensitivity coefficient, it can be tested and be measured by temperature calibration；KεIt, can for ga(u)ge factor
To be measured by straining calibration experiment.
When fiber grating is used for sensing measurement, since strain and temperature can all cause the variation of bragg wavelength, individually
The change of bragg wavelength caused by fiber bragg grating itself can not tell strain and temperature respectively, to cannot achieve
Accurate measurement.Solve the problems, such as that this is all based on greatly the thought of 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 that eliminating temperature bring influences.Since two fiber gratings are under a mutually synthermal environment, they are with temperature
Variation be it is identical, their temperature raises simultaneously when the temperature increases, their temperature reduces simultaneously when the temperature decreases, and
When element stress, since fiber grating is on tow sides, so a fiber grating tension, central wavelength increases, another
A fiber grating is pressurized, and central wavelength reduces.So their strain measurement value is highlighted.So using method ten using this
Divide reliable effective.
According to above formula it is found that 2 fiber gratings being pasted onto the same temperature environment are influenced phase by temperature effect
Together, for monitor strain grating phase wavelength drift subtract the central wavelength as caused by temperature change drift can be obtained by by
The caused wave length shift of measured object strain, to obtain the strain value of current measured object.Temperature is eliminated to survey by this method
The influence measured one's own ability, following scheme have also used the method.
In conclusion shown in final scheme schematic diagram such as Fig. 1 (a) and Fig. 1 (b):
Influence of the temperature to wavelength can also can be greatly reduced with this radial mounting method to which protrusion is answered in fiber grating
Become the influence to wavelength, because test needs to measure the strain of Wheel/Rail Contact Point, fiber grating should be pasted as far as possible
In the place close to wheel improve measurement accuracy, and wheel sticks four also for the precision for improving measurement on one side.
2, experimental program
In this experiment, it needs to measure two power, is normal force (i.e. normal pressure) and cross force (i.e. frictional force) respectively,
This first sketches the production principle of two power, and marks their action direction, as shown in Figure 2.
Normal force (i.e. normal pressure): simulation train in orbit when driving, train because of itself gravity-pressing wheel track, so
Normal force is directed to the application of the bull wheel center of circle.With steamboat analog orbit, then normal force can apply to pre-tighten by steamboat and force
Tight bull wheel is realized, sets 1000N for the normal force on bull wheel.
Cross force (i.e. frictional force): simulation train turning when, because of the presence of friction factor, then train by
To a frictional force, this power is called cross force by we, and direction is perpendicular to big wheel surface.Cross force is constantly to change,
But numerical value is no more than 250N, we can generate cross force by changing the angle of attack of two-wheeled, and the cross force on bull wheel is set
It is 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 measuring devices, including steamboat assemble mechanism 100, bull wheel assemble mechanism 200, (FBG) demodulator and industrial personal computer；
The steamboat assemble mechanism includes support plate and the steamboat being fixed in the support plate and small wheel assembly, support plate
On be fixed with steering wheel, steamboat by steering wheel and be located at steamboat two sides bracket it is fixed on the supporting plate, in small wheel assembly
Under the action of steamboat rotate freely；Angle of attack adjuster is also equipped in the support 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
Take turns shaft 23, bearing 24, bracket 25, steering wheel 26, front end panel 27, gear wheel 28, worm gear 29, pinion 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
Since accuracy of alignment is good, installation, disassembly convenience, therefore utilize the effect of high-intensitive stress bolt, in the inner ring of expansion sleeve and small
Between wheel shaft, enclasping force is generated between the outer ring of expansion sleeve and steamboat wheel hub, and then realizes the connection of steamboat and steamboat shaft,
Angular contact ball bearing is used to support steamboat shaft and steamboat, reduces the coefficient of friction in rotary course and guarantees its rotating accuracy,
Therefore the inner ring of angular contact ball bearing and steamboat shaft, outer ring are all made of transition fit with bracket and connect, since steamboat utilizes swelling
Set is mounted in steamboat shaft, therefore steamboat shaft utilizes small for bearing moment of flexure and torque of the steamboat in rotation work, bracket
Shaft is taken turns supporting steamboat, being connected cradle bottom surface with bolt and fastening on the steering wheel, becomes steamboat, bracket, steering wheel
One entirety, therefore the angle of attack between steamboat and bull wheel can be adjusted by changing the rotation angle of steering wheel；By large and small gear shaft
It is installed on front end panel, then steering wheel and worm gear is respectively installed on large and small gear shaft from front end panel front surface and are used in combination
Nut is tightened, and large and small gear is respectively installed on large and small gear shaft (large and small gear phase at this time from front end panel rear surface
Mutually engage and torque can be transmitted) and tightened with nut, worm screw, which is mounted 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, and in forward and backward branch to transmit torque by engagement
Installation force bolt and force nut between fagging.When using tool rotary worm, since worm and wheel engages so that snail
Wheel rotates, and worm and wheel is driven by 1:60, and worm gear drives pinion gear to rotate by pinion shaft, due to pinion gear and greatly
Gear engages so that gear wheel rotates, and pinion gear and gear wheel are driven by 1:6, and gear wheel is driven by Large Gear Shaft and turned to
Disc spins make steamboat and turn to dish type since steamboat is fixed on the steering wheel by expansion sleeve, steamboat shaft, bearing and bracket
At an entirety, therefore steamboat rotates together with steering wheel, makes to form certain angle of attack between steamboat and bull wheel, and since torque exists
Total transmission ratio is 1:360 in transmittance process, 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
In the same plane, wheel side is tangent for heart plane；The two sides of bull wheel are symmetrically installed with multiple fiber gratings, multiple fiber grating
Tail optical fiber is connect with (FBG) demodulator again after passing through fiber spinning shaft coupling；
Light source built in (FBG) demodulator is transferred in each fiber grating by rotary connector, with the rotation of bull wheel, greatly
The rolling contact point of wheel and steamboat generates the normal force and cross force acted on bull wheel, and passes to fiber grating, optical fiber light
Grid generate transient strain force signal；(FBG) demodulator demodulates the transient strain signal of fiber grating, and demodulated signal is sent
To industrial personal computer；
Industrial personal computer is connect with frequency converter, and the revolving speed of the variable-frequency motor for controlling bull wheel, the industrial personal computer is also used 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
Bull wheel is found out in the transient state side-friction coefficient of 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 fiber grating in one end connection rotation of connector, the other end of the optical fiber rotary joint do not rotate and pass through weldering
Wire jumper is connect to be connected on (FBG) demodulator.
Normal force and cross force due to bull wheel in rolling contact point all directly act 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, passes through the transient strain of detection fiber grating
Transient state normal force and transient state cross force are measured, thus can find out bull wheel in the transient state side-friction system of rolling contact point
Number.
1) normal force measures: when steamboat it is whole with bull wheel after the assembly is completed, apply steamboat to bull wheel by screwing bolts
The power that one size is 1000N, as normal force.When bull wheel is by normal force, bull wheel can generate compressive strain due to being pressurized, therefore
4 fiber bragg gratings are pasted on one side in bull wheel, but requirement is symmetrical two-by-two, when wherein 1 compression, another 3 are in nature shape
State compares.Because the state that bull wheel is pressurized is only in the contact point of bull wheel and steamboat, only 1 grating state changes,
As a comparison by the grating on its opposite, the value for solving normal force is measured.
2) cross force measures: when steamboat it is whole with bull wheel after the assembly is completed, screwing bolts make the method that 1000N is generated on bull wheel
Xiang Li, then worm screw, which turns an angle, makes to form certain angle of attack between bull wheel and steamboat, at this point, not only can between them
Normal force is generated, while also having a lateral creep, generates lateral creep power, as cross force.When bull wheel is by cross force
When, the one side of bull wheel understands tension and generates stretching strain, and another side can be pressurized and generate compressive strain, therefore symmetrical in bull wheel tow sides
4 groups of fiber bragg gratings are pasted, but requires symmetrical two-by-two and is uniformly distributed, wherein some fiber grating tension on front produces
Raw stretching strain, and symmetrical another fiber grating compression generates compressive strain therewith on reverse side, compares.Because bull wheel is by cross
To power state only at the contact point of bull wheel and steamboat, so the state of only one group fiber grating changes, by the group
Symmetrical two fiber gratings are compared, and measure the value for finding out normal force.
Based on above-mentioned apparatus, the present invention is based on the measurement sides of the rolling contact point transient state side-friction coefficient of fiber grating
Method, specifically includes the following steps:
S1, the side that the different fiber grating of central wavelength is pasted on to bull wheel, in the symmetrical of the bull wheel other side
The different fiber grating of central wavelength, and successively label are equally pasted on position；
S2, adjusting bull wheel and steamboat generate certain normal force at rolling contact point, and make to produce between bull wheel and steamboat
Raw certain angle of attack, so that bull wheel generates certain cross force at rolling contact point；
S3, the revolving speed for controlling bull wheel, when bull wheel rotation, the strain signal that bull wheel generates passes to fiber grating, demodulates
Light source built in instrument is transferred in each fiber grating by fiber grating rotary connector, and fiber grating generates strain signal；
S4, (FBG) demodulator demodulate the strain signal of fiber grating, and demodulated signal is sent to industrial personal computer, industrial personal computer
Demodulated signal is acquired and is analyzed, transient state of the bull wheel at rolling contact point is calculated according to the wave length shift of fiber grating
Normal pressure and frictional force.
3, experiment content
The sensitivity coefficient of fiber bragg grating measures, if the sensitivity coefficient of fiber grating influences less or can
Sensitivity can not be demarcated, at this by (strain or temperature) sensitivity coefficient identical in formula eliminating deformation formula
To eliminate temperature and Strain-coupled problem in experiment, so sensitivity coefficient must re-scale.
This experiment carries out strain measurement using fiber Bragg grating sensor.By experimental program it is found that in this experiment
In, it needs first to make a kind of fiber-optic grating sensor and carries out strain calibration experiment, to measure the strain spirit of fiber-optic grating sensor
Quick coefficient.Then, then another fiber-optic grating sensor progress testing stand contact point strain measurement experiment is made, 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.
3.1, calibration experiment is strained
Ga(u)ge factor in order to obtain determines to use control variate method, first makes the temperature centainly i.e. subsequent number of formula
Value is certain, then change subsequent strain of formula, while measuring the data of central wavelength drift, carries out statistics using public affairs
The ga(u)ge factor of formula calculating fiber bragg grating.
For obtain fiber Bragg grating sensor strain measurement precision, use dynamometer complete the coefficient of strain calibration with
And control experiment, it studies under different loads, central wavelength drift is continuously applied to power on the element for post fiber grating,
(FBG) demodulator measurement obtains central wavelength after its numerical stability, and dynamometer reads the size of power.
3.2, the measurement of correlation of normal force (normal pressure)
Experimental bench after the assembly is completed, is completed the integral installation of bull wheel and steamboat, is then installed additional between bull wheel and steamboat
Dynamometer.It is bolt force application apparatus at the rear of steamboat, makes to generate normal force between bull wheel and steamboat by rotating bolt, not
Disconnected screwing bolts are gradually increased normal force until reaching 1000N (being determined by the dynamometer between bull wheel and steamboat), simultaneously
Record the wavelength data of fiber grating at this time.
Detailed process:
1) by 8 different fiber gratings of central wavelength from 1~8 successively label, and the welding that joins end to end in order
Together, wherein the other end of No. 8 fiber gratings is connected and welds together with wire jumper.Then use viscose glue by fiber grating
It is pasted on the position corresponding with label of bull wheel two sides.Test error can be prevented using eight fiber gratings, and eliminates temperature
The influence for spending coupling, shown in bull wheel such as Fig. 1 (a) and Fig. 1 (b) after pasting fiber grating；
2) unscrew anchor nut and extract foundation bolt out, the assembly for supporting steamboat is moved backward into a lattice, make bull wheel with
Gap between steamboat is slightly larger than the length of dynamometer, and the position of adjustment assembly body is aligned bull wheel with steamboat, is inserted into 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 and steamboat clamp dynamometer (survey
Power meter both ends are fitted without pull ring).Dynamometer is connected with display again and powers on display.Finally adjustment is aobvious
Show the scaling position of device, the instrument unit of display, and measurement range (can to specifications on operating process carry out).
Confirm after adjustment is suitable by origin.At this point, will show the pressure (normal direction i.e. between bull wheel and steamboat being subject on display
Power)；
4) tail optical fiber of wire jumper is inserted into the connectivity port of (FBG) demodulator, then (FBG) demodulator is connect with computer by cable, then
General supply and opening display power supply are opened, computer sensing testing software is started.The point under the menu of computer sensing software
Connection is hit, (FBG) demodulator is connected and Computer signal transmits, after showing successful connection, sample frequency (for 4KHz) is set gradually, leads to
Road and gain (being up to 79).Click starts to measure, and software will show the obtained data of (FBG) demodulator, while there is record to protect
Function (each second can be reserved for 4000 data) is deposited, the acquisition and preservation of data can be completed；
5) bolt in screwing bolts force application apparatus, gradually increases the normal force between bull wheel and steamboat, works as display
When being above 1000N (normal force between bull wheel and steamboat is 1000N), stop screwing bolts, while recording optical fiber at this time
The wavelength data of grating.
3.3, 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, the transverse direction of 200N is then applied at the rolling contact point of bull wheel by dynamometer
Power, while recording the wavelength data of fiber grating at this time.
Detailed process:
1) bolt for unscrewing bolt force application apparatus takes off dynamometer between bull wheel and steamboat；
2) it unscrews anchor nut and extracts foundation bolt out, the assembly of steamboat will be supported integrally to remove from experimental bench；
3) pull ring for screwing on and tightening dynamometer both ends, at the rolling contact point on the pull ring and bull wheel of dynamometer one end
(i.e. when bull wheel and steamboat contact, position of the two-wheeled contact point on bull wheel) (cord can bear 200N's or more by cord
Pulling force) it connects, then a cord will be also connected on the pull ring of the dynamometer other end, finally apply one in the free end of cord
Fixed pulling force；
4) dynamometer is connected with display and powers on display.Finally adjust the decimal point of display
Set, the instrument unit of display, and measurement range (can to specifications on operating process carry out).By original after adjustment is suitable
Point confirmation, at this point, will show the pressure (normal force i.e. between bull wheel and steamboat) being subject on display；
5) tail optical fiber of wire jumper is inserted into the connectivity port of (FBG) demodulator, then (FBG) demodulator is connect with computer by cable, then
General supply and opening display power supply are opened, computer sensing testing software is started.The point under the menu of computer sensing software
Connection is hit, (FBG) demodulator is connected and Computer signal transmits, after showing successful connection, sample frequency (for 4KHz) is set gradually, leads to
Road and gain (being up to 79).Click starts to measure, and software will show the obtained data of (FBG) demodulator, while there is record to protect
Function (each second can be reserved for 4000 data) is deposited, the acquisition and preservation of data can be completed；
6) pulling force for constantly increasing cord free end, gradually increases cross force suffered by bull wheel, when being on display
When 200N (cross force between bull wheel and steamboat is 200N), stops increasing the pulling force of cord free end immediately and keep the drawing
Power is constant, while recording the wavelength data of fiber grating at this time.
3.4, 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 mounted on experimental bench.It is exerted a force by bolt
Device makes the normal force that 1000N is generated between bull wheel and steamboat, makes to form certain punching between bull wheel and steamboat by rotary worm
Wire jumper is passed through contactless optical fiber connector and is connected on (FBG) demodulator by angle and the cross force for generating 200N, and control bull wheel becomes
Frequency motor makees constant speed rotary, such as 100r/min with a certain suitable revolving speed, and the strain signal of fiber grating is adopted with (FBG) demodulator
Collect and save, the data obtained is handled and calculates rolling contact point transient state normal force (normal pressure) and cross force
(frictional force), then transient state side-friction coefficient can be obtained by formula.
In this experiment, since testing stand bull wheel needs to rotate, the fiber grating after encapsulating on bull wheel cannot be straight
It is connected on (FBG) demodulator in succession, because the rotation of bull wheel will drive the rotation of optical patchcord if being directly connected to, so as to cause wiring
Head can not be fixed.It is this to solve the problems, such as, connection line of optic fibre is filled in shaft coupling, pulls out and is welded from right side.
Optical fiber junction is a kind of contactless optical fiber connector, inside be an optical fiber rotary joint, its one
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 this non-rotary end
Wire jumper is connected on (FBG) demodulator, so just solves the above problem.
Detailed process:
1) assembly for supporting steamboat is placed in situ, then loads onto foundation bolt and tightens anchor nut,
The assembly of support steamboat is fixed on testing stand；
2) wire jumper is passed through contactless optical fiber connector, then the connectivity port of the tail optical fiber insertion (FBG) demodulator wire jumper,
(FBG) demodulator is connect with computer by cable, general supply and opening display power supply are then opened, starts computer sensing testing
Software.Connection is clicked under the menu of computer sensing software, connects (FBG) demodulator and Computer signal transmits, show successful connection
Afterwards, sample frequency (for 4KHz), channel and gain (being up to 79) are set gradually.Click starts to measure, and software will show solution
The obtained data of instrument are adjusted, while having the function of that record saves (each second can be reserved for 4000 data), data can be completed
Acquisition and preservation；
3) bolt constantly in screwing bolts force application apparatus, the pretightning force for applying steamboat to bull wheel are gradually increased, are being revolved
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 at this time between bull wheel and steamboat reaches 1000N；
4) (clockwise or counterclockwise) continuous rotary worm toward the direction, so that between bull wheel and steamboat
The angle of attack constantly increases, and gradually increases so as to cause cross force between bull wheel and steamboat, 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 rotating worm screw, illustrates at this time between bull wheel and steamboat
Cross force reach 200N.It shuts down computer sensing testing software；
5) electronic box that will control motor is opened, and master switch gets on, by combined floodgate/separating brake switch clockwise torsion (i.e. opening
Pass is screwed on combined floodgate), open computer on " KingView " software (KingView be on industrial personal computer be used to control variable-frequency motor operation shape
The software of state, by the way that the drive manner of variable-frequency motor is directly arranged on the software, such as square wave, triangular wave, sine wave, constant speed,
The speed of service, wavelength and amplitude run to control variable-frequency motor according to the state in scheme), " RUN " is clicked, the control is opened
Bull wheel is arranged with constant speed rotary in the parameter setting interface of software, and rotation speed is set as 100r/min, and amplitude and period all set
It is 0, clicks " parameter confirmation ", press the green start button of electronic box, motor rotates and drives bull wheel with 100r/ by gear-box
The revolving speed constant speed rotary of min；
6) after bull wheel constant revolution, start computer sensing testing software.The point under the menu of computer sensing software
Hit " connection ", connect (FBG) demodulator and Computer signal and transmit, after showing successful connection, set gradually sample frequency (for 4KHz),
Channel and gain (being up to 79).Click starts to measure, and software will show the number of the obtained optic fiber grating wavelength of (FBG) demodulator
According to, while having the function of that record saves (each second can be reserved for 4000 data), that is, complete the acquisition 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, is handled, and is calculated bull wheel according to the wave length shift of fiber grating and is being in rolling contact
Transient state normal pressure and frictional force at point.Since coefficient of friction is the ratio of frictional force and normal pressure, then can be calculated by formula
Transient state side-friction coefficient of the bull wheel in rolling contact point out.
It should be understood that for those of ordinary skills, it can be modified or changed according to the above description,
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 measurement method of the rolling contact point transient state side-friction coefficient based on fiber grating, which is characterized in that including
Following steps:
The different fiber grating of central wavelength is pasted on to the side of bull wheel, it is same on the symmetrical position of the bull wheel other side
Sample pastes the different fiber grating of central wavelength, and successively label；
It adjusts bull wheel and steamboat generates certain normal force at rolling contact point, and make to generate centainly between bull wheel and steamboat
The angle of attack, so that bull wheel generates certain cross force at rolling contact point；
Light source built in (FBG) demodulator is transferred in each fiber grating by fiber grating rotary connector, controls turning for bull wheel
Speed, when bull wheel rotation, the strain signal that bull wheel generates passes to fiber grating, and fiber grating generates strain signal；
(FBG) demodulator demodulates the strain signal of fiber grating, and demodulated signal is sent to industrial personal computer, and industrial personal computer is to demodulation
Signal is acquired and analyzes, and calculates transient state normal pressure of the bull wheel at rolling contact point according to the wave length shift of fiber grating
With frictional force.
2. the method according to claim 1, wherein 4 fiber gratings are pasted in bull wheel two sides respectively.
3. the method according to claim 1, wherein fiber grating is fixed along bull wheel diametrical direction.
4. a kind of measuring device of the rolling contact point transient state side-friction coefficient based on fiber grating, which is characterized in that including
Steamboat assemble mechanism, bull wheel assemble mechanism, (FBG) demodulator and industrial personal computer；
The steamboat assemble mechanism includes support plate and the steamboat being fixed in the support plate and small wheel assembly, is consolidated in support plate
Surely have a steering wheel, steamboat by steering wheel and be located at steamboat two sides bracket it is fixed on the supporting plate, in the work of small wheel assembly
It is rotated freely with lower steamboat；Angle of attack adjuster is also equipped in the support 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 two sides of bull wheel are symmetrically installed with multiple fiber gratings, and the tail optical fiber of multiple fiber grating passes through
It is connect again with (FBG) demodulator after fiber spinning shaft coupling；
Light source built in (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 generates the normal force and cross force acted on bull wheel, and passes to fiber grating, and fiber grating produces
Raw transient strain force signal；(FBG) demodulator demodulates the transient strain signal of fiber grating, and demodulated signal is sent to work
Control machine；
Industrial personal computer is connect with frequency converter, and the revolving speed of the variable-frequency motor for controlling bull wheel, the industrial personal computer is also used 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, is thus found out
Transient state side-friction coefficient of the bull wheel in rolling contact point.
5. device according to claim 4, which is characterized in that the rotary connector is contactless optical fiber connector,
It is internally provided with optical fiber rotary joint, 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 is not rotated and is connected on (FBG) demodulator by welding wire jumper.
6. device according to claim 4, which is characterized in that paste 4 fiber gratings, 8 optical fiber respectively in bull wheel two sides
Grating welds together, then accesses (FBG) demodulator by a wire jumper.
7. device according to claim 4, which is characterized in that fiber grating is encapsulated using sealant.
8. device according to claim 7, which is characterized in that the sealant is epoxy resin AB glue.
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| CN108645635A (en) * | 2018-05-30 | 2018-10-12 | 武汉理工大学 | Wheel track testing stand based on fiber grating and its contact force measuring method |
| CN113029933B (en) * | 2021-02-26 | 2021-11-16 | 广东利元亨智能装备股份有限公司 | Welding quality detection system, ultrasonic welding equipment and welding quality detection method |
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