CN106546657B - It is a kind of for detecting the eddy current probe annular array method in carbon fibre composite laying direction - Google Patents
It is a kind of for detecting the eddy current probe annular array method in carbon fibre composite laying direction Download PDFInfo
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- 239000000523 sample Substances 0.000 title claims abstract description 68
- 239000002131 composite material Substances 0.000 title claims abstract description 31
- 238000000034 method Methods 0.000 title claims abstract description 30
- 239000000835 fiber Substances 0.000 title claims abstract description 26
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 18
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 18
- 229920000049 Carbon (fiber) Polymers 0.000 claims abstract description 20
- 239000004917 carbon fiber Substances 0.000 claims abstract description 20
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 20
- 230000001939 inductive effect Effects 0.000 claims abstract description 11
- 239000000284 extract Substances 0.000 claims abstract description 4
- 238000010586 diagram Methods 0.000 claims description 8
- 230000005284 excitation Effects 0.000 claims description 3
- 239000011800 void material Substances 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 9
- 239000011120 plywood Substances 0.000 abstract description 3
- 238000000605 extraction Methods 0.000 abstract description 2
- 238000003384 imaging method Methods 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 2
- 238000003491 array Methods 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 230000002929 anti-fatigue Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000003032 molecular docking Methods 0.000 description 1
- 238000009659 non-destructive testing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
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Abstract
The invention discloses a kind of for detecting the eddy current probe annular array method in carbon fibre composite laying direction, and annular array, the selection of progress eddy current probe optimal frequency, eddy current probe automatic bias including building eddy current probe are adjusted, extract signal characteristic information and calculated signal amplitude, shown that normalized signal and laying orientation angle are determined using polar coordinates.Carbon fibre composite laying direction detection method of the invention combines linear transducer array method and Near resonance oscillating frequency working method carries out the extraction of probe signal inductive voltage value, the information in carbon fiber layer plywood laying direction is showed with polar form, it can accurately and effectively realize the judgement of carbon fibre composite laminate laying, image taking speed is fast, imaging results are clear, reliable, intuitive and easy to understand.
Description
Technical field:
The present invention relates to carbon fibre composite technical field of nondestructive testing, more particularly to one kind are multiple for detecting carbon fiber
The eddy current probe annular array method in condensation material laying direction.
Background technique:
The excellent mechanical property of carbon fibre composite, especially have specific strength is high, specific stiffness is big, designability is strong,
The features such as corrosion-resistant and good antifatigue damage, makes the material to become more and more popular in auto manufacturing and aerospace
One of material.Carbon fibre composite is superimposed together by certain direction by multilayer carbon fiber/epoxy resin thin slice and is made, each
Fiber direction is identical in layer.In practical application, for the mechanical strength for improving anisotropy, improving composite material entirety, phase
Adjacent bed machine direction is then laid with as requested.In this way, machinery of the directionality of carbon fiber arrangement to composite material structural member
Performance, such as tensile strength, stretcher strain, the formation of aspect intensity ratio, vertically and horizontally ratio of elongation, stress distribution and drilling defects
And electric property all has a direct impact.For guarantee carbon fibre composite quality and normal use, to composite structure
Direction, that is, laying direction research of middle carbon fiber arrangement is very necessary.It is different from metallic article, carbon fibre composite
Thin sight construction be a complicated heterogeneous system, and be uneven and the multiphase opposite sex, dielectric epoxy resin in material
In the presence of so that lamina shows very strong anisotropy on electric property.Due to the electric conductivity of carbon fiber, so that whirlpool in plate
Stream is elongated in machine direction, and is compressed in remaining direction.Therefore, laying direction in eddy-current method measurement composite material can be used
Information, so in evaluation structure fiber alignment directionality.
Currently, the method for detection fiber direction is mainly rotary eddy current detecting probe method, this method passes through probe rotation
The mode of turning reaches testing goal, therefore there is certain defects and limitations:
(1) conventional rotary eddy current probe method is to change detection angles by rotating detector, and successively acquisition angles change
When detection signal, the signal of all directions in surface of test piece is obtained with this.
(2) to obtain the inductive signal on circumferencial direction at Difference angles, multiple rotary and positioning probe are needed.So
And in actually detected, the distance between probe and test specimen to be measured can inevitably change, and then introducing measurement error,
Detection sensitivity is had a huge impact.
(3) in actual field application, need quick and precisely to detect the device of carbon fiber orientation particularly with those
For, undoubtedly increase the error rate of detection time and result.
Summary of the invention:
The purpose of the present invention is to propose to a kind of for detecting the eddy current probe circular array in carbon fibre composite laying direction
Column method, this method obtain the structural information of carbon fiber layer plywood using a transmitting-how received eddy current probe annular array mode,
And process is extracted and processed using follow-up signal, finally combine polar coordinate representation method to show carbon fiber in a manner of image multiple
Fiber architecture information in condensation material structure can accurately and effectively realize the identification of carbon fiber layer plywood machine direction, imaging
Speed is fast, as a result clearly, reliably, it is intuitive and easy to understand.
The present invention adopts the following technical scheme: a kind of for detecting the eddy current probe ring in carbon fibre composite laying direction
Shape Array Method, including the following steps:
Step 1: it constructs the annular array of eddy current probe: equably arranging eddy current probe by circular pattern in the structure, and
Guarantee that eddy current probe covers the whole region of engineering structure to be measured, eddy current probe is send-receive probe, is connect using a transmitting
Debit's formula；
Step 2: it carries out the selection of eddy current probe optimal frequency: after completing arranged to receiving transducer, determining that transmitting is visited
The optimum working frequency of head, to reach in a manner of Optimum Excitation；
Step 3: eddy current probe automatic bias is adjusted: the send-receive probe of array being located in air, locking phase is passed through
The automatic bias of amplifier, which is adjusted, is set to 0 for the real and imaginary parts voltage of receiving transducer at this time, then, by the transmitting-of array
Receiving transducer is placed in carbon fiber layer board structure surface；
Step 4: it extracts signal characteristic information and calculates signal amplitude: by Step 1: two and three eddy current probe circular arrays
Column mode detects the signal in carbon fiber composite structure at different location, and records the real part V of position eddy current signalx
With imaginary part Vy.Obtaining each receiving transducer inductive voltage valueAfterwards, to the probe obtained in 0 ° of -360 ° of angle
Signal is normalized, normalized signal V'(θ ') it indicates are as follows:
V'(θ ')=Δ V (θ ')/Vmax
Wherein, Δ V (θ ') be receiving transducer be located at angle, θ ' when receiving transducer inductive voltage value, VmaxIt is different angle
The maximum value of coil voltage；
Step 5: show normalized signal using polar coordinates: the normalized signal obtained according to step 4 utilizes polar coordinates
Method draws normalized inductive voltage value；
Step 6: laying orientation angle determines: being carried out according to the polar diagram that step 5 is drawn to laminate laying direction
Analysis changes size according to eddy current signal and judges laying directional information, and the angle position of local maximum indicates machine direction,
The size order of signal value is corresponding with ply stacking-sequence.
Further, the optimum working frequency is the resonant frequency of nearly transmitting probe.
Further, the receiving transducer is arranged by annular array mode, each receiving transducer and transmitting probe center spacing
For 10mm.
The invention has the following beneficial effects:
(1) according to influence of the different directions conductivity size to coil signal amplitude in carbon fibre composite, using ring
The current vortex signal of different circumferencial directions in the current vortex sensing unit acquisition structure of shape distribution.It is vortexed receiving transducer annular array
Method shortens detection time, while the measurement error for avoiding the mechanical rotation of single probe and thus introducing.The circular array
Column method has the characteristics that non-contact, non-intervention and non-harmful.By obtaining and analyzing by conductivity variations institute in material structure
Caused coil receives signal, is all-sidedly and accurately reflected in composite structure using polar coordinate representation method by fiber architecture direction
Variable quantity caused by changing realizes the identification to fiber laying direction in carbon fiber composite structure.This for field application,
For those devices for quickly detecting of requirement, a undoubtedly much progress.
(2) present invention includes arrangement eddy current probe array manner, the selection of exciting signal frequency, receiving transducer signal extraction
And fleece-laying direction determines several steps in composite structure.Wherein, vortex receiving transducer by annular array mode come
Reach the scanning detected to 360 ° of regions in geodesic structure, shortens detection time, the measurement eliminating mechanical rotation and thus introducing
Error；It using reasonable data acquisition equipment, is adjusted by automatic bias, records the eddy current signal in whole circumference region；Root
According to the signal amplitude of record and the physical location of receiving transducer, each signal is normalized；It is in using polar coordinate mode
The normalized signal of position on existing circumference；Size is finally changed according to eddy current signal and judges laying directional information, local pole
The angle position being worth greatly indicates machine direction, and the size order of signal value is corresponding with ply stacking-sequence.
Detailed description of the invention:
Fig. 1 is the process of eddy current probe annular array method of the present invention for detecting carbon fibre composite laying direction
Figure.
Fig. 2 is probe annular array schematic diagram.
Fig. 3 is probe signal and coil impedance comparison schematic diagram.
Fig. 4 is the eddy current signal schematic diagram on carbon fiber board under different coil-spans.
Fig. 5 (a), 5 (b), 5 (c) are the polar diagrams of the online ring signal of carbon fiber board under three kinds of different layings.
Specific embodiment:
The present invention program is described in detail below in conjunction with attached drawing.Before following embodiment is with technical solution of the present invention
It mentions and being implemented, give specific embodiment and operating process, but the scope of protection of the invention is not limited to following implementation
Example.
Step 1: the annular array of eddy current probe is constructed.Eddy current probe equably is arranged by circular pattern in the structure, and
Guarantee that eddy current probe covers the whole region of engineering structure to be measured, eddy current probe is send-receive probe, is connect using a transmitting
The position of debit's formula, each receiving transducer need to keep a fixed spacing with transmitting probe, avoid the vortex weight near due to transmitting coil
The influence of overlay receiving coil signal.Receiving transducer is arranged by annular array mode, between each receiving transducer and transmitting probe center
Away from for 10mm.
As shown in Fig. 2, the eddy current probe at annular center will be chosen by taking the array manner that 17 sensors are constituted as an example
In, as transmitting probe, remaining 16 annular array eddy current probe is as receiving transducer.In general, vortex is near transmitting coil
Region overlaps, if receiving coil is close from transmitting coil, as in Fig. 3 at position 1, and whirlpool in all directions in overlay region at this time
Flow valuve differs very little, and the signal amplitude variation of each receiving coil is little on circumferencial direction.To guarantee the accurate and reliable of testing result,
By taking the array manner that 17 sensors are constituted as an example, the arrangement of receiving transducer is made to meet following condition:
(a) 16 receiving coils and the transmitting coil center spacing at annular center are 10mm；
(b) the centric angle difference of 16 receiving coils circumferentially should be the minimum angle that machine direction in structural member is greater than 0
The half of degree guarantees detection sensitivity.By taking 45 ° of machine directions as an example, then differential seat angle is 22.5 °.
When meeting above-mentioned two condition, the influence of the vortex overlapping docking take-up ring signal near transmitting coil becomes very
It is small, it receives signal and is generated by the electric current extended in machine direction, as shown in Figure 4.
Step 2: the selection of eddy current probe optimal frequency is carried out.After completing arranged to receiving transducer, using frequency sweep side
Formula determines the optimum working frequency of transmitting probe, to reach optimum mode of operation.The big expression of the resistance of excitation coil is being passed through phase
With under driving voltage, coil energizing current is small, this is unfavorable for raising space magnetic field intensity and receiving coil voltage.For
Eddy current probe in the present embodiment, when frequency is the 2.45MHz less than resonant frequency point, when, the electricity that induces in receiving coil
Pressure value is maximum, as shown in Figure 3.Wherein optimum working frequency is the resonant frequency of nearly transmitting probe.
Step 3: eddy current probe automatic bias is adjusted.The send-receive probe of array is located in air, locking phase is passed through
The automatic bias of amplifier, which is adjusted, is set to 0 for the real and imaginary parts voltage of receiving transducer at this time.Then, by the transmitting-of array
Receiving transducer is placed in carbon fiber composite structure surface.
Step 4: it extracts signal characteristic information and calculates signal amplitude: by Step 1: two and three eddy current probe circular arrays
Column mode detects the signal in carbon fiber composite structure at different location, and records the real part V of position eddy current signalx
With imaginary part Vy.Obtaining each receiving transducer inductive voltage valueAfterwards, to the probe obtained in 0 ° of -360 ° of angle
Signal is normalized, normalized signal V'(θ ') it indicates are as follows:
V'(θ ')=Δ V (θ ')/Vmax
Wherein, Δ V (θ ') be receiving transducer be located at angle, θ ' when receiving transducer inductive voltage value, VmaxIt is different angle
The maximum value of coil voltage；
Step 5: show normalized signal using polar coordinates: the normalized signal obtained according to step 4 utilizes polar coordinates
Method draws normalized inductive voltage value；
Step 6: laying orientation angle determines.According to step 5 draw polar diagram to composite plys direction into
Row analysis, by drawing signal with the fiber alignment in the measurable carbon fiber composite structure out of polar diagram of angle change
Direction.Changing size according to eddy current signal and judges laying directional information, the angle position of local maximum indicates machine direction,
The size order of signal value is corresponding with ply stacking-sequence.
By taking the carbon fibre composite plate under three kinds of different layings as an example, normalized polar coordinates show result such as Fig. 5
It is shown, it is confirmatory measurement as a result, giving FEM Numerical Simulation and experimental measurements in figure together.Experimental result is by solid line
'-', indicates that simulation result is indicated by dotted line ' --- '.
Wherein eddy current probe is fiber direction in laminated plate structure to be obtained by the purpose that annular array mode constructs.
In method of the invention, in arrangement eddy current probe array manner step 1, if the number of receiving transducer is nature
Number is N number of, and distribution and performance must satisfy following condition: (1) N number of receiving transducer allows for constituting array side symmetrically
Formula；(2) differential seat angle of N number of receiving transducer in a circumferential direction is greater than angle, θ；(3) center of N number of receiving transducer and transmitting probe
Overlapping region is vortexed away from being greater than.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
It for member, can also make several improvements without departing from the principle of the present invention, these improvement also should be regarded as of the invention
Protection scope.
Claims (3)
1. a kind of for detecting the eddy current probe annular array method in carbon fibre composite laying direction, it is characterised in that: including
The following steps:
Step 1: it constructs the annular array of eddy current probe: equably arranging eddy current probe by circular pattern in the structure, and guarantee
Eddy current probe covers the whole region of engineering structure to be measured, and eddy current probe is send-receive probe, using the more recipients of transmitting
Formula；
Step 2: it carries out the selection of eddy current probe optimal frequency: after completing arranged to receiving transducer, determining transmitting probe
Optimum working frequency, to reach in a manner of Optimum Excitation；
Step 3: eddy current probe automatic bias is adjusted: the send-receive probe of array being located in air, is amplified by locking phase
The automatic bias of device, which is adjusted, is set to 0 for the real and imaginary parts voltage of receiving transducer at this time, then, by the send-receive of array
Probe placement is in carbon fiber layer board structure surface；
Step 4: it extracts signal characteristic information and calculates signal amplitude: by Step 1: two and three eddy current probe annular array sides
Formula detects the signal in carbon fiber composite structure at different location, and records the real part V of position eddy current signalxAnd void
Portion Vy, obtaining each receiving transducer inductive voltage valueAfterwards, to the probe signal obtained in 0 ° of -360 ° of angle
It is normalized, normalized signal V'(θ ') it indicates are as follows:
V'(θ ')=Δ V (θ ')/Vmax
Wherein, Δ V (θ ') be receiving transducer be located at angle, θ ' when receiving transducer inductive voltage value, VmaxIt is that different angle is online
Enclose the maximum value of voltage；
Step 5: show normalized signal using polar coordinates: the normalized signal obtained according to step 4 utilizes polar coordinate method
Draw normalized inductive voltage value；
Step 6: laying orientation angle determines: laminate laying direction analyzed according to the polar diagram that step 5 is drawn,
Change size according to eddy current signal and judge laying directional information, the angle position of local maximum indicates machine direction, signal
The size order of value is corresponding with ply stacking-sequence.
2. it is as described in claim 1 for detecting the eddy current probe annular array method in carbon fibre composite laying direction,
Be characterized in that: the optimum working frequency is the resonant frequency of nearly transmitting probe.
3. it is as described in claim 1 for detecting the eddy current probe annular array method in carbon fibre composite laying direction,
Be characterized in that: the receiving transducer is arranged by annular array mode, and each receiving transducer and transmitting probe center spacing are 10mm.
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| US20230288373A1 (en) * | 2022-02-28 | 2023-09-14 | Verifi Technologies, Llc | Eddy current probe and method for determining ply orientation using eddy current and ultrasonic probes |
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|---|---|---|---|---|
| JPS595945A (en) * | 1982-07-02 | 1984-01-12 | Shimadzu Corp | Eddy current flaw detecting method |
| US4922201A (en) * | 1989-01-09 | 1990-05-01 | The United States Of America As Represented By The Secretary Of The Navy | Eddy current method for measuring electrical resistivity and device for providing accurate phase detection |
| CN104897774A (en) * | 2015-05-13 | 2015-09-09 | 南京航空航天大学 | Eddy current microscopic construction imaging method of carbon fiber composite material |
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