CN202757915U - Multi-main-frequency combined SH0-mode electromagnetic acoustic transducer - Google Patents
Multi-main-frequency combined SH0-mode electromagnetic acoustic transducer Download PDFInfo
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- CN202757915U CN202757915U CN 201220007224 CN201220007224U CN202757915U CN 202757915 U CN202757915 U CN 202757915U CN 201220007224 CN201220007224 CN 201220007224 CN 201220007224 U CN201220007224 U CN 201220007224U CN 202757915 U CN202757915 U CN 202757915U
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Abstract
The utility model relates to a multi-main-frequency combined SH0-mode electromagnetic acoustic transducer and belongs to the field of nondestructive testing. The multi-main-frequency combined SH0-mode electromagnetic acoustic transducer comprises a signal input BNC (bayonet nut connector), a signal output BNC, a pulse electromagnet power supply BNC, a magnet fixing plate, a protecting shell, pulse electromagnets and an inflection coil, the inflection coil is arranged in a groove of the bottom surface of the protecting shell, the pulse electromagnets are arranged in the protecting shell, the magnet fixing plate is arranged above the pulse electromagnets, a cover plate of the protecting shell is arranged at the uppermost end of the protecting shell, and the signal input BNC, the signal output BNC and the pulse electromagnet power supply BNC are fixed on the cover plate. The signal input BNC and the signal output BNC are connected into terminals on the upper side and on the lower side of the inflection coil respectively, and the pulse electromagnet power supply BNC is connected to windings of the pulse electromagnets. Compared with an EMAT (electromagnetic acoustic transducer) with an equivalent periodic coil, the multi-main-frequency combined SH0-mode electromagnetic acoustic transducer can pay attention to information of multiple frequency points and can substitute for multiple EMATs with different frequencies for frequency sweeping.
Description
Technical field
The utility model belongs to field of non destructive testing, is specifically related to a kind of SH0 mode Electromagnetic Acoustic Transducer (EMAT, Electromagnetic Acoustic Transducer) of many dominant frequency combinations.
Background technology
Horizontal shear wave (SH ripple) is a kind of supersonic guide-wave of propagating in plate structure, and its propagation characteristic is very tempting in the guided wave context of detection.SH only produces the shear direction vibration that is parallel to the plate face in plate, when running into the interface consistent with its particle vibration direction reflex time occurs, and MODAL TRANSFORMATION OF A does not occur the SH ripple.In addition, the zeroth order mode of SH ripple is frequency dispersion not, and velocity of propagation is lower, has higher spatial resolution under the equal instrument condition.Thereby the SH ripple is widely used in all kinds of defects detection and monitoring structural health conditions of plate.
EMAT is the sonac with periodic distribution structure, is convenient to very much produce in-plane displacement, therefore often is used to produce in test specimen the SH ripple.Its characteristics are, sensor is optionally excitation or receive the wavelength mode consistent with its distribution cycle always.Can motivate on the test specimen surface displacement of different directions by loop shape and the distribution collocation that is installed with magnetic field.Therefore, loop shape is the key of EMAT design with the design that is installed with magnetic field.Fig. 1 is SH ripple EMAT commonly used.
Coil:
For the scissoring vibration that produces the SH ripple is provided, the coil of SH ripple EMAT adopts the inflection type coil usually, when passing into the electric current of alternation in the coil, produce the moving field of alternation on the surface of ferromagnetism test specimen, this moving field with by the static magnetic field reciprocation that is installed with magnet and produces, in the surperficial or nearly superficial layer of test specimen, produce the vibration of shearing and to direction (left and right directions among the figure) propagation that coil extends, namely formed the SH ripple.
Coil width has determined the aperture of sensor, thereby has determined the beam width of the sound wave that sensor motivates.When coil width was larger, the acoustic beam that sensor motivates was more concentrated, and sensor directive property is better; When coil width more hour, the acoustic beam that sensor motivates is loose all the more, and is larger with the zone that equidistant lower sensor covers.But the design of coil width should consider simultaneously sensor directive property demand and by increase bias magnet that coil width brings away from (being just reducing of biased magnetic field strength).
Coil period has determined the wavelength of the sound wave that sensor can encourage and receive, and the wavelength of sound wave is coil period.Current opposite in direction in the coil in adjacent two line segments, its spacing should be half of wavelength.When tested material decision, the frequency of its sound wave that can encourage and receive that coil period is then corresponding.Periodicity just because of coil is arranged, and has realized the mode selectivity of EMAT.
The coil period number is larger, and the acoustic wave energy that sensor can motivate is larger, but simultaneously can the time motivate signal the time domain width lengthen, thereby reduced the time domain resolving power that detects.When running into the nearer defective of gathering, signal is stack, indistinguishable mutually.
Magnet:
EMAT adopts permanent magnet that bias magnetic field is provided usually.This mode is simple and convenient, but Shortcomings in actual applications.When sensor frequency lower (coil period is larger), for equally distributed magnetic field is provided, need select the larger magnet of volume.This will cause sensor too heavy, and detected object return when being ferrimagnet be not easy to mobile.
The design of above coil and magnet has caused SH ripple EMAT commonly used in the deficiency that receives on signal amplitude, time domain resolving power and the sensor flexibility.
The utility model content
In order to solve the shortcoming on existing EMAT reception signal amplitude, time domain resolving power and the sensor flexibility, a kind of SH0 mode Electromagnetic Acoustic Transducer of many dominant frequency combinations.
This sensor is comprised of signal input BNC connector 1, signal output BNC connector 2, impulse mgnet power supply BNC connector 3, magnet fixed head 4, protecting sheathing 5, impulse mgnet 6 and inflection type coil 7, as shown in Figure 2.Inflection type coil 7 places in containment vessel 5 bottom recesses, and containment vessel inside is equipped with impulse mgnet 6, is magnet fixed head 4 on it.The top at protecting sheathing is the cover plate of protecting sheathing, is fixed with signal input BNC connector 1, signal output BNC connector 2 and impulse mgnet power supply BNC connector 3 on it.
Described magnet fixed head 4, purpose are to fix two blocks of electromagnet, and guaranteeing under the effect of high-intensity magnetic field, two electromagnet can adhesive.
Described protecting sheathing 5 provides protection for whole sensor.Signal input BNC connector 1, signal output BNC connector 2 and impulse mgnet power supply BNC connector 3 place the protecting sheathing top.Magnet fixed head 4 places protecting sheathing inner with impulse mgnet 6, and the inflection type coil is fixed in the groove of protecting sheathing bottom, as shown in Figure 3.In order to characterize the distribution of each element of enclosure, the protecting sheathing among Fig. 3 is simplified model, and the real protection shell should comprise the pit, groove of particular design so that fixed pulse electromagnet and inflection type coil.
Described impulse mgnet 6, for having the impulse mgnet of square core, require magnetic direction under magnet evenly and perpendicular direction downwards/upwards, the opposite direction in the magnetic field that two impulse mgnets produce, as shown in Figure 3.During work, pulse signal of excitation in the coil of impulse mgnet, its width should be greater than pumping signal.Two impulse mgnets can form a direction is pointed to another impulse mgnet by an impulse mgnet bias magnetic field on the test specimen surface.The number of turn of impulse mgnet and electrical current should design according to required biased magnetic field strength.
Described inflection type coil 7 is fixed in the groove of protecting sheathing 5 bottoms.The coil period of described inflection type coil 7 is also unequal, but changes according to certain rule, and coil is printed on the printed circuit board (PCB), and upper epidermis aligns from beginning to end with the coil that lower top layer is printed, but its regularity of distribution is opposite, as shown in Figure 4.
The principle of work of the sensor of common inflection type coil as shown in Figure 5, the sensors with auxiliary electrode were utilization be the magnetostrictive effect of material.Permanent magnet or electromagnet form bias magnetic field B on the test specimen surface
0, when passing into electric current in the coil, electrified wire can be set out magnetic field B at the test specimen surface induction
m, moving field and bias magnetic field quadrature meet the producing method of maximum shear, and both magnetic field of closing is B
HIf when material was negative magnetostriction material (such as nickel etc.), under the impact of bias magnetic field, the lattice of material was compressed, shown in figure among Fig. 5.At this moment, if introduce the moving field that electrified wire produces, then lattice can be shown in two figure about among Fig. 5.When passing into the electric current of alternation in the inflection type coil, just produced reciprocal scissoring vibration, thereby formed the SH ripple.The current opposite in direction of two adjacent wires in the inflection type coil, the moving field opposite direction of its generation, thereby the half-wavelength of the sound wave that produces always the interval is consistent therewith.
And what adopt in the utility model is the SH0 mode coil of many dominant frequency combination, improves in the principle of common inflection type coil, and its principle as shown in Figure 6.The coil period of the SH0 mode inflection type coil of many dominant frequency combinations is also unequal, because coil is always selected the excitation wavelength sound wave corresponding with coil period, so the coil of unequal-interval can go out at the test specimen underexcitation SH0 mode of different wave length.Because SH0 mode is frequency dispersion not, the SH velocity of wave propagation of each frequency is consistent, and the sequencing that therefore only need when designing excitation with receiving coil different coil period be distributed is corresponding, can finish the frequency modulation (PFM) to coil.The SH ripple of each frequency is propagated at the test specimen internal independence, (during a sharp receipts pattern, adopt two coils that distribute in the same way on two pcb boards, during the self excitation and self receiving pattern and the distribution of excitation and receiving coil is consistent, adopt two coils that oppositely distribute on the same pcb board, as shown in Figure 6).Therefore, each frequency SH wave propagation distance equates, thereby the travel-time also equates.On the time domain, each frequency SH ripple can be in identical time point stack.
The utlity model has following advantage,
1) the SH ripple of each frequency superposes at synchronization, has greatly increased the amplitude that receives signal, and shortens the time domain width of signal when increasing amplitude, can obtain higher time domain resolving power;
2) the coil EMAT with the cycle of grade compares, and the utility model can be paid close attention to the information of a plurality of Frequency points simultaneously, and by signal post-processing, can substitute the EMAT that utilizes a plurality of different frequencies carries out frequency sweep;
3) because the frequency band of sensor can be according to design modifying, and can in time domain, improve signal amplitude by the compressed signal width, thus lower to the requirement of pumping signal, adopt pulse excitation or sine-wave excitation to get final product.This greatly reduces the requirement to detecting instrument.
4) because sensor adopts impulse mgnet that bias magnetic field is provided, thereby sensor can not adsorb ferrimagnet when not switching on, and has greatly improved the dirigibility of sensor.
Below in conjunction with description of drawings and embodiment the utility model is described in further detail.
Description of drawings
Fig. 1: the structural drawing of common SH ripple inflection type coil EMAT
Fig. 2: sensor wiring layout
Fig. 3: sensor internal structural drawing
Fig. 4: loop construction schematic diagram
Fig. 5: inflection type coil fundamental diagram
Fig. 6: working sensor schematic diagram
Among the figure, 1-signal input BNC connector, 2-signal output BNC connector, 3-impulse mgnet power supply BNC connector, 4-magnet fixed head, 5-protecting sheathing, 6-impulse mgnet, 7-inflection type coil.
Embodiment
Implementation step of the present utility model comprises:
A kind of is that magnetostriction materials or surface are covered with in the plate of magnetostriction materials in material; excitation produces the Electromagnetic Acoustic Transducer of the SH0 ripple of single many dominant frequency combinations, is comprised of signal input BNC connector 1, signal output BNC connector 2, impulse mgnet power supply BNC connector 3, magnet fixed head 4, protecting sheathing 5, impulse mgnet 6 and inflection type coil 7.
Processing and assembling process:
Protecting sheathing 5 is covering and the support of whole sensor; long 70mm; wide 50mm, high 15mm is processed by engineering plastics; the thick 3mm of upper top; be processed with the BNC connector hole on it, the bottom has long 65mm, and the dark groove of the 1mm of wide 45mm is with fixing inflection type coil circuit board; have through hole in wiring place, be convenient to coil and BNC connector wiring.
Inflection type coil 7 in the load map 2, its physical dimension is long 65mm, wide 45mm, the PCB circuit board of thick 0.5mm, tangible such as the inflection type coil in the central area of circuit board, adjacent two conductor spacings of coil spacing, its current opposite in direction is changed to 2mm from 5mm, totally 13 sections.
The impulse mgnet 6 of packing into, impulse mgnet 6 be by long 60mm, wide 10mm, and the strip iron core of high 10mm is outer to be that 20 winding consists of around the number of turn.
The magnet fixed head of packing into.BNC connector is fixed in the protecting sheathing top cover; the lower top layer terminals that connect signal input BNC connector 1 and inflection type coil 7; connect signal output BNC connector 2 and 7 times top layer terminals of inflection type coil, connect the winding of impulse mgnet power supply BNC connector 3 and impulse mgnet 6.Cover plate that the BNC connector protecting sheathing the is housed threaded hole by 4 drift angles of shell is fixed on the protecting sheathing.
Using method:
Typical case's detection system is comprised of signal generator, power amplifier, sensor, prime amplifier and digital oscilloscope.
When adopting self excitation and self receiving to arrange, signal generator produces the rect.p. that pulsewidth is 1 μ s, and behind power amplifier, in the input pickup, sensor is positioned over a block length approximately on the nickel plate of 1m, wide 120mm, thick 1mm.Sound wave is back and forth propagated at plate width direction, and the end face echo of reception receives via sensor, outputs to digital oscilloscope via the change-over circuit of power amplifier inside and shows.
When adopting one to swash a receipts layout, signal generator produces the rect.p. that pulsewidth is 1 μ s, behind power amplifier, in the input stimulus sensor, receiving sensor is positioned at apart from the about 300mm place of stimulus sensor, and the signal of reception outputs to digital oscilloscope via preposition amplification and shows.
When the distribution that is distributed in drive coil of receiving coil is consistent (the even echo and that comprises the self excitation and self receiving pattern swashs a receipts pattern), signal is compressed in time domain, and amplitude is larger, and the time domain resolving power is better, has realized mentality of designing of the present utility model.
Claims (5)
1. the SH0 mode Electromagnetic Acoustic Transducer of dominant frequency more than kind combination, by signal input BNC connector (1), signal output BNC connector (2), impulse mgnet power supply BNC connector (3), magnet fixed head (4), protecting sheathing (5), impulse mgnet (6) and inflection type coil (7) form; Inflection type coil (7) places in containment vessel (5) bottom recesses, and containment vessel inside is equipped with impulse mgnet (6), is magnet fixed head (4) on it; The top at protecting sheathing is the cover plate of protecting sheathing, is fixed with signal input BNC connector (1) on the cover plate, signal output BNC connector (2), impulse mgnet power supply BNC connector (3); Signal input BNC connector (1), signal output BNC connector (2) accesses respectively the terminals of inflection type coil above and below, and impulse mgnet power supply BNC connector (3) is connected to the winding of impulse mgnet; In order to the impulse mgnet (6) of bias magnetic field that vertical direction is provided for producing the opposite strip electromagnet of magnetic direction, two not adhesives of impulse mgnet.
2. the SH0 mode Electromagnetic Acoustic Transducer of a kind of many dominant frequency combinations described in according to claim 1, it is characterized in that: described protecting sheathing (5) is engineering plastics.
3. the SH0 mode Electromagnetic Acoustic Transducer of a kind of many dominant frequency combinations described in according to claim 1, it is characterized in that: described impulse mgnet (6) is for having the impulse mgnet of strip iron core, require magnetic direction under magnet evenly and perpendicular direction downward or upward; During work, pulse signal of excitation in the coil of impulse mgnet, its width should be greater than the pumping signal of inflection type coil (7).
4. the SH0 mode Electromagnetic Acoustic Transducer of the described a kind of many dominant frequency combinations in according to claim 1, it is characterized in that: the coil period of described inflection type coil (7) is unequal, coil is printed on the printed circuit board (PCB), upper epidermis aligns from beginning to end with the coil that lower top layer is printed, but its regularity of distribution is opposite.
5. the SH0 mode Electromagnetic Acoustic Transducer of the described a kind of many dominant frequency combinations in according to claim 1, it is characterized in that: its assembling process is, the inflection type coil (7) of packing in protecting sheathing (5) bottom, the impulse mgnet (6) of in protecting sheathing (5), packing into, the magnet fixed head (4) of packing into is with fixed magnet; BNC connector is fixed in the protecting sheathing top cover, connects BNC connector and the signal wire of inflection type coil (7) and the winding of BNC connector and impulse mgnet (6); The top board that BNC connector protecting sheathing (5) will be housed is fixed on the protecting sheathing by the threaded hole of 4 drift angles of shell.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN 201220007224 CN202757915U (en) | 2012-01-09 | 2012-01-09 | Multi-main-frequency combined SH0-mode electromagnetic acoustic transducer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201220007224 CN202757915U (en) | 2012-01-09 | 2012-01-09 | Multi-main-frequency combined SH0-mode electromagnetic acoustic transducer |
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| CN202757915U true CN202757915U (en) | 2013-02-27 |
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| CN 201220007224 Withdrawn - After Issue CN202757915U (en) | 2012-01-09 | 2012-01-09 | Multi-main-frequency combined SH0-mode electromagnetic acoustic transducer |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102608220A (en) * | 2012-01-09 | 2012-07-25 | 北京工业大学 | Multi-basic frequency combined SH0 model electromagnetic acoustic transducer |
| CN103439418A (en) * | 2013-07-29 | 2013-12-11 | 北京工业大学 | Low-order torsional mode electromagnetic acoustic array transducer |
| CN105738471A (en) * | 2014-12-11 | 2016-07-06 | 安徽惠洲地质安全研究院股份有限公司 | Portable intelligent electronic wall-tapping and roof-knocking apparatus |
| CN106324098A (en) * | 2016-08-01 | 2017-01-11 | 北京工业大学 | Metal plate defect detecting method based on omni-directional SH0 electromagnetic sound sensor array |
| CN106442741A (en) * | 2016-02-03 | 2017-02-22 | 河南中原光电测控技术有限公司 | Electromagnetic ultrasonic transducer for automatic detection of roller surface |
-
2012
- 2012-01-09 CN CN 201220007224 patent/CN202757915U/en not_active Withdrawn - After Issue
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102608220A (en) * | 2012-01-09 | 2012-07-25 | 北京工业大学 | Multi-basic frequency combined SH0 model electromagnetic acoustic transducer |
| CN102608220B (en) * | 2012-01-09 | 2013-08-21 | 北京工业大学 | Multi-basic frequency combined SH0 model electromagnetic acoustic transducer |
| CN103439418A (en) * | 2013-07-29 | 2013-12-11 | 北京工业大学 | Low-order torsional mode electromagnetic acoustic array transducer |
| CN103439418B (en) * | 2013-07-29 | 2015-08-19 | 北京工业大学 | A kind of low-order torsional mode electromagnetic acoustic array transducer |
| CN105738471A (en) * | 2014-12-11 | 2016-07-06 | 安徽惠洲地质安全研究院股份有限公司 | Portable intelligent electronic wall-tapping and roof-knocking apparatus |
| CN105738471B (en) * | 2014-12-11 | 2018-06-19 | 安徽惠洲地质安全研究院股份有限公司 | A kind of smart electronics tap portable instrument |
| CN106442741A (en) * | 2016-02-03 | 2017-02-22 | 河南中原光电测控技术有限公司 | Electromagnetic ultrasonic transducer for automatic detection of roller surface |
| CN106442741B (en) * | 2016-02-03 | 2019-01-25 | 河南中原光电测控技术有限公司 | A kind of electromagnet ultrasonic changer for roller surface automatic detection |
| CN106324098A (en) * | 2016-08-01 | 2017-01-11 | 北京工业大学 | Metal plate defect detecting method based on omni-directional SH0 electromagnetic sound sensor array |
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| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20130227 Effective date of abandoning: 20130821 |
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| RGAV | Abandon patent right to avoid regrant |