CN102520068B - Rail destruction detection method based on magnetostriction and longitudinal ultrasonic guided wave - Google Patents
Rail destruction detection method based on magnetostriction and longitudinal ultrasonic guided wave Download PDFInfo
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- CN102520068B CN102520068B CN 201110403882 CN201110403882A CN102520068B CN 102520068 B CN102520068 B CN 102520068B CN 201110403882 CN201110403882 CN 201110403882 CN 201110403882 A CN201110403882 A CN 201110403882A CN 102520068 B CN102520068 B CN 102520068B
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Abstract
The invention discloses a rail damage detection device and method based on magnetostriction and longitudinal ultrasonic guided wave, which are applied in the field of railway traffic nondestructive detection. The rail damage detection device comprises a shell, wherein an inner wire support, an inner coil, an outer wire support, an outer coil, a yoke and a permanent magnet are arranged in the shell; a current input port, an inner coil current input electric wire and an inner coil current output electric wire are arranged at one end of the shell; an outer coil current output electric wire, an outer coil current loop electric wire and a voltage output port are arranged at the other end of the shell; and the upper part of the shell is fixedly connected with a rail detection vehicle. The rail damage detection method comprises the following steps of: exciting induced electromotive force by utilizing magnetostriction and longitudinal ultrasonic guided wave, and indirectly measuring time and strength generated by a defect reflective waveguide signal according to the induced electromotive force, and further determining the destruction position and the destruction size. The rail damage detection device and method can be used for carrying out accurate detection on trace destruction inside and outside the rail, and have the advantages of long detection distance and high detection efficiency.
Description
Technical field
The present invention relates to the track traffic field of non destructive testing, particularly a kind of rail damage detecting method based on magnetostrictive technology and longitudinal ultrasonic guided wave technology.
Background technology
Current track traffic field of non destructive testing is to utilize the detection meanss such as leakage method, osmosis, eddy-current method to carry out damage check to rail mostly.Simultaneously, people are also using rays method and supercritical ultrasonics technology to be monitored the track degree of injury.What widely apply now is the track detection vehicle technology.This detection system is mainly at postposition started track detection vehicle platform upper set ultrasound wave and electromagnetic induction detection technique and optical sensor.In addition, Britain Imperial College has developed a longitudinal ultrasonic guided wave rail damage check equipment based on piezoelectric sensor.Univ California-San Diego USA has designed and has manufactured a mode of flexural vibration supersonic guide-wave rail damage check equipment based on laser technology.
All there is respectively following defect in various degree in said method:
(1) leakage method, as K.Sawley, R.Reiff. wait the article that the exercise question delivered is " An assessment of Railtrack ' s methods for managing broken and defective rail. ", the method rig-site utilization is very simple, but the direct-detection surface imperfection, but as tested surface of the work coating or humidity are arranged, detecting reliability will greatly reduce, so, must first remove coating, dry surface.This has just limited to this method efficiency in actual use widely.
(2) osmosis, the method effects on surface opening crackle detection sensitivity is very high, but effects on surface has the workpiece of coating and humidity just undesirable, and the judgement of defect being depended on to reviewer's experience, this can not meet the needs of extensive rail damage check.
(3) eddy-current method, the method is to be based upon on the basis of electromagnetic induction, utilizes under action of alternating magnetic field, the eddy current that various amplitude and phase place can occur different materials detects the difference of physical property, defect and the structure situation of ferromagnetism and nonferromugnetic material.For ferrimagnet, usually it is magnetized to state of saturation, then detected by nonferromugnetic material.But detection method of eddy and as above two kinds of methods all can only detect surface or the near surface flaw of metallic conductor, detect the degree of depth very shallow, to the damage of rail inside, can't know.
(4) rays method is very effective to the detection of defect under workpiece surface, but the x radiation x harmful to human must carry out security protection during detection, and some operating mode is difficult for implementing.
(5) ultrasonic Detection Method is very effective to the detection of defect under workpiece surface, but needs couplant while detecting, and efficiency is lower, the judgement of defect is also depended on to technician's experience.Main is that the method adopts point-to-point metering system, can only detecting sensor structure in the subrange of below, fail effectively hyperacoustic energy to be focused on the longitudinal direction of rail, so its directionality is not strong, causes detection efficiency low and to the more difficult realization of the assessment of degree of injury.Too short and small for the slow and rail circuit of sensing range with respect to hundreds and thousands of kilometers of the method detection speed.The speed of disposing the track detection vehicle of ultrasonic equipment is greatly limited by the detection principle of this equipment.Therefore, by as above detection technique is in conjunction with in Systems for optical inspection, " data overrun " is still an obvious problem.But then, while by mathematical principle, calculating and processing these data, the method for these mathematics is not good at and is processed the unusual feature occurred in track, as the crossing of track etc.
(6) the longitudinal ultrasonic guided wave rail damage check equipment based on piezoelectric sensor of Britain Imperial College design is because of close contact between piezoelectric sensor needs and rail, so need detected position, rail surface to scribble couplant, this just makes by the position rail of this sensor of cramping must keep bright and clean smooth, corrosion can not occur, otherwise be difficult to realize coupling.But the greatest problem of this equipment is piezoelectric sensor, be that the contact guided wave excites and receiving device, therefore, each detection at least need 20 minutes and while detecting equipment can not on rail, move, can't realize online damage check.This point has greatly restricted detection efficiency for the rail of thousands of kilometers.
(7) although the equipment that Univ California-San Diego USA researches and develops has been used contactless laser technology excitation ultrasound guided wave, the supersonic guide-wave that this technology excites is mode of flexural vibration.It is short that this mode and longitudinal wave guide are compared propagation distance, and undesired signal is many.The laser signal amplifier is unstable and the detection signal noise is excessive.Therefore, the track detection vehicle that this checkout equipment carries only can be moved detection to rail with the speed of 10 miles per hours, and this efficiency still can not meet the requirement of extensive rail damage check.
Therefore, need to provide a kind of and not only can all accurately detect the damage of rail inside and outside, and high rail damage detection apparatus and the method for detection efficiency.
Summary of the invention
The object of the invention is to overcome the shortcoming of prior art with not enough, a kind of rail damage detecting method based on magnetostriction and longitudinal ultrasonic guided wave is provided, the method can all can accurately detect the damage of rail inside and outside, detects distance, and detection efficiency is high.
The invention discloses a kind of rail damage detection apparatus based on magnetostriction and longitudinal ultrasonic guided wave, comprise shell, and setting interior layer line holder, inner coil, outer layer line holder, outer coil, yoke, permanent magnet in the enclosure, and the current input terminal mouth, inner coil electric current input electric wire, the inner coil electric current output electric wire that are arranged on shell one end, and the outer coil electric current output electric wire, outer coil current return electric wire, the Voltage-output port that are arranged on the shell other end, described shell upper is fixedly connected with the rail inspection vehicle, the rectangular parallelepiped that described interior layer line holder is a lower ending opening, the shape of its lower ending opening position shape and rail rail head is complementary, inner coil is arranged in interior layer line holder, outer layer line holder is arranged on the outside of inner coil, with interior layer line holder edge, be fixedly connected with, outer coil is arranged in outer layer line holder, yoke is arranged on the outside of outer layer line holder, the inboard edge with outer layer line holder of yoke fixes, permanent magnet sticks on top, the yoke outside, permanent magnet top and inboard, shell top fix, interior layer line holder and yoke bottom all are fixedly installed on both sides of the edge, shell bottom, described inner coil and outer coil are some sections alternately both positive and negative polarity coil compositions, there are 4 wires described inner coil lower end, and two are connected with inner coil electric current input electric wire, export electric wire with the inner coil electric current for two, and the current input terminal mouth all is connected with inner coil electric current output electric wire with inner coil electric current input electric wire, there are 4 wires described outer coil lower end, and two are connected with outer coil electric current output electric wire, two and outer coil current return electric wire, and the current input terminal mouth all is connected with outer coil current return electric wire with outer coil electric current output electric wire, described current input terminal mouth and Voltage-output port are fixed on the two ends on top, the shell outside respectively, described current input terminal mouth and external signal generator, Voltage-output port and external signal treatment facility.
Concrete, in described inner coil and outer coil, diameter of wire is encouraged and is accepted frequency and the wavelength decision of ultrasonic guided wave signals by it.
Concrete, the wire in described inner coil and outer coil is hard coil or soft circuit line, such as being the hard coil such as enameled wire, can be also the soft circuit lines such as winding displacement of printed circuit board (PCB).
Preferably, in described inner coil and outer coil every section alternately the width of both positive and negative polarity coil be half of supersonic guide-wave wavelength.
Concrete, described external signal generator specifically comprises: for generation of the waveform generator that detects required electrical signal of the frequency; For the power amplifier that electric signal is amplified.
Concrete, described external signal treatment facility specifically comprises: for electromotive force signal being converted to the preposition modulate circuit of digital signal; Data acquisition unit; For calculating the processor of damage position and lesion size.
Purpose of the present invention is achieved through the following technical solutions: a kind of rail damage detecting method based on magnetostriction and longitudinal ultrasonic guided wave, at first the external signal generator produces to detect and uses signal, be input to the current input terminal mouth after amplifying, inner coil produces a dynamic magnetic field according to the variation of input signal, with the magnetic field of permanent magnet generation, be coupled simultaneously, inspire along the supersonic guide-wave of rail longitudinal propagation, once supersonic guide-wave runs into the rail defect, can pass a defect reflection signal back, this defect reflection signal is converted to the alternating magnetic field of this frequency, this alternating magnetic field inspires induction electromotive force in outer coil, indirectly measure according to this induction electromotive force the time and intensity that the defect reflection guided wave signals produces, thereby determine the position of damage and the size of damage.
Specifically comprise the following steps:
(1) calculate the dispersion curve of rail according to rail model and sectional dimension, select the guided wave centre frequency of the type rail supersonic guide-wave damage check according to dispersion curve;
(2) produce one by waveform generator and detect required electric signal, this electric signal waveform is consistent with detection guided wave waveform and guided wave centre frequency; Then this electric signal is imported to power amplifier, electric signal is amplified;
(3) electric signal after amplifying is entered to inner coil through the current input terminal mouth, in inner coil each section alternately the both positive and negative polarity coil produce the dynamic magnetic field of corresponding frequencies in rail under the electric signal effect, the quiescent biasing magnetic field that this magnetic field and permanent magnet produce is coupled, make the magnetized state of object to be detected that the variation under this frequency occur, make on the object to be detected longitudinal size and change, it is magnetostrictive strain, thereby excitation ultrasound guided wave, supersonic guide-wave is along the rail longitudinal propagation, simultaneously, outer coil produces an initial induction electromotive force corresponding with encouraged supersonic guide-wave by magnetostrictive back wash effect, this initial induction electromotive force outputs to the external signal treatment facility by the Voltage-output port, the external signal treatment facility records size and the generation time of this initial induction electromotive force,
(4) once there be supersonic guide-wave to run into the rail defect, can pass a defect reflection signal back, utilize magnetostrictive back wash effect, can produce an identical alternating magnetic field of frequency with it in outer coil, this alternating magnetic field inspires a feedback-induced electromotive force corresponding with the defect reflection guided wave in outer coil, this feedback-induced electromotive force outputs to the external signal treatment facility by the Voltage-output port, and the external signal treatment facility records size and the generation time of this feedback-induced electromotive force;
(5) according to the relational expression of induction electromotive force and ultrasonic guided wave signals intensity, initial induction electromotive force and the size of feedback-induced electromotive force and the quantitative relationship between induction electromotive force and ultrasonic guided wave signals intensity, intensity conversion by initial induction electromotive force and feedback-induced electromotive force is also measured the intensity of defect reflection guided wave signals, thereby determines the big or small degree of damage; Determine the quantitative relationship between ultrasonic guided wave signals intensity and defect size according to the stress wave principle, simultaneously, mistiming between the time of the induction electromotive force that the time of the induction electromotive force that the defect reflection signal recorded by equipment produces and excitation supersonic guide-wave produce, with the distance of determining that supersonic guide-wave is propagated in rail, thereby obtain the accurate location that defect exists.
The supersonic guide-wave method damage check principle of using in the present invention is according to the elastic stress wave propagation principle.That is, supersonic guide-wave belongs to a kind of propagation condition of elastic stress wave, as shown in Figure 7.Elastic stress wave is along elongate rod architecture (as: rail, while pipeline etc.) propagating, when running into this structure because of physical dimension or the caused wave impedance variation of change of shape, as: there is crack 18 in rail, when this cross section, place, crack (can be xsect or oblique section) physical dimension changes, the variation of wave impedance must occur at this section in rail.According to the stress wave principle, when be energized longitudinal ultrasonic guided wave 15 in slim-lined construction, when it is transmitted to crack 18, wave impedance can change, the longitudinal ultrasonic guided wave 15 of original incident can return to form flaw echo 16 by antireflection part, and part meeting transmission is crossed this cross section continuation propagation and formed transmitted wave 17.Therefore, time of arrival by recording defect reflection wave 16 signals be multiplied by the speed that this ripple propagates in rail and can judge the position that damage exists.The benefit of this principle is, when the sightless damage of small range estimation occurs geometrical scale, the variation of its wave impedance is quite huge, to such an extent as to enough cause one can be by oscillograph recording observable defect reflection signal.So the method is for finding that there is significant meaning in small infant cracking and the crack of rail inside, the probability that greatly reduction accident occurs.
The detection principle of magneto strictive sensor realizes by magneto-striction phenomenon.Its structure is to place a permanent magnet in the detected material external body object to be detected is magnetized as shown in Figure 1, thus it to require object to be detected be ferromagnet.And arrange one deck coil (the design's inner coil is 3) at object to be detected near surface (noncontact).When coil passes into the electric current with certain frequency change, can in object to be detected, produce the dynamic magnetic field of corresponding frequencies, coupling occurs in the quiescent biasing magnetic field that this magnetic field and permanent magnet produce, make the magnetized state of object to be detected that the variation under this frequency occur, make on the object to be detected longitudinal size and change, be magnetostrictive strain, thus the excitation ultrasound guided wave.Otherwise, utilize magnetostrictive back wash effect, when the defect reflection signal is passed back, can produce the dynamic change magnetic field that frequency is identical with it, produce induction electromotive force in coil (outer coil 5 in the present invention), the defect that the size of measuring this induction electromotive force by outer coil 5 just can be obtained guided wave transmits simultaneously.By recording the mistiming between the induction electromotive force that flaw echo that inner coil 3 pumping signals and outer coil 5 receive causes, just can determine the position of damage.Because certain distance is arranged between coil and object to be detected, therefore the benefit of this sensor is to realize to long distance, ferromagnet carries out contactless damage check on a large scale, and can adapt to higher temperature and severe working environment, be suitable for the online damage check of the rail that track detection vehicle is in operation.
The principle of work of apparatus of the present invention is by the permanent magnet in this equipment, yoke to be magnetized, thereby produces a quiescent biasing magnetic field around it, and will be magnetized by the rail of this equipment overlay area.Then the AC signal (for example, 10 cycle sinusoidal electric signals of 300KHz Hanning window modulation commonly used) to input fixed frequency in current feedback circuit by signal generation apparatus.This electric current is laid the rule conduction according to inner coil, it can produce a dynamic magnetic field the same with institute galvanization change frequency by galvanomagnetic effect, the static magnetic field that permanent magnet is produced is upset, alternately changing of this frequency occurs in rail surface magnetization state, thereby vertically produce the change in size under this frequency at it, then motivate the longitudinal ultrasonic guided wave of this frequency, as shown in Figure 3.When the longitudinal ultrasonic guided wave runs into defect, this equipment place occurs to reflect and be delivered to, according to magnetostrictive back wash effect principle, the defect reflection signal of this frequency can be converted to the alternating magnetic field of this frequency, and there are quantitative relationship in alternating magnetic field intensity and guided wave signals intensity.Simultaneously, this alternating magnetic field can inspire induction electromotive force in outer coil, and this winding wire is connected induction electromotive force is exported with rear end Voltage-output port.
There is following funtcional relationship between induction electromotive force and ultrasonic guided wave signals intensity:
Wherein k is the supersonic guide-wave wave number, the number of turn that n is receiving coil, and the cross-sectional area that s is receiving coil, the length that l is receiving coil, d is the axial distance between receiving coil and drive coil, ν is supersonic guide-wave velocity of wave in ferromagnetic material, μ
rfrom being the ferromagnetic material relative permeability, λ is the ferromagnetic material magnetostriction constant, H
0it is the function of coil turn and electric current.
Can determine the quantitative relationship between the intensity of the size of induction electromotive force and supersonic guide-wave by this formula; Simultaneously, can determine the quantitative relationship between ultrasonic guided wave signals intensity and rail defect size according to the stress wave principle; And the time that induction electromotive force produces is poor with the time life period of excitation guided wave, this mistiming be guided wave in rail, propagate and run into defect reflection after pass the time that excites position back.Therefore, can indirectly measure the time and intensity that the defect reflection guided wave signals produces by this induction electromotive force of apparatus measures, thereby determine the position of damage and the size of damage.
The present invention compared with prior art, has following advantage and beneficial effect:
The inventive method all is applied to the rail damage check by magnetostrictive technology and longitudinal ultrasonic guided wave method, and the longitudinal ultrasonic guided wave is different from traditional ultrasound wave, and it has very strong directionality, is similar to the difference of laser and normal optical.This detection method is to one of long method apart from the rod shaped structure damage check.The supersonic guide-wave used due to the method can, effectively at the rail surface excitation, can distribute guided wave and vertically propagate at a high speed along rail in the whole cross section of rail.Therefore the method can not only detect the rail cross section major injuries such as rail break, can detect rail surface and inner early stage sightless wire fine crack simultaneously, so the method can improve the efficiency of rail damage EARLY RECOGNITION.Simultaneously because guided wave is as fast the speed of this Propagation as the velocity of sound in the speed of Propagation, so this detection method efficiency is high.The method good directionality, penetration capacity is strong, energy high (energy is greater than sound wave) and comparatively concentrated.The detection principle of magneto strictive sensor realizes by magneto-striction phenomenon.The benefit of this sensor is to realize the long distance contactless damage check of ferromagnet on a large scale, and can adapt to higher temperature and severe working environment, is suitable for the online damage check of the rail that track detection vehicle is in operation.In conjunction with not only checking the geometry flatness on rail surface, can find rail surface and inner fine crack and core wound by the two simultaneously, can effectively find the rail earlier damage, reduce the accident probability caused because of reasons such as rail damage or fractures.The method detects distance, and detection efficiency is high.Each excitation ultrasound guided wave and complete damage check and only need the hundreds of microsecond, so this equipment can carry realize the online damage check to rail on track detection vehicle.
The accompanying drawing explanation
Fig. 1 is apparatus of the present invention mechanical part structural representation;
Fig. 2 is the schematic diagram of STRUCTURE DECOMPOSITION shown in Fig. 1;
Fig. 3 is that inner coil of the present invention and circuit connecting mode reach and interior layer line holder putting position schematic diagram;
Fig. 4 is the circuit theory schematic diagram of inner coil of the present invention and current feedback circuit;
Fig. 5 is that outer coil of the present invention and circuit connecting mode reach and outer layer line holder putting position schematic diagram;
Fig. 6 is the circuit theory schematic diagram of outer coil of the present invention and voltage sensor;
Fig. 7 is longitudinal ultrasonic guided wave damage check principle schematic;
Fig. 8 is magnetostriction excitation supersonic guide-wave principle schematic in rail;
Fig. 9 is apparatus of the present invention operating process schematic diagram;
Figure 10 is schematic appearance when in embodiment, apparatus of the present invention are applied;
Figure 11 is signal graph measured in the embodiment of the present invention.
In Fig. 2: the 1-rail; The holder of 2-line; The 3-inner coil; The outer layer line holder of 4-; 5 outer coils, 6-yoke, 7-permanent magnet, 8 shells, 9-current input terminal mouth, 10-electrical inner layer coil current input electric wire, 11 ?inner coil electric current output electric wires, 12 ?outer coil electric current output electric wires, 13 ?outer coil current return electric wires, 14 ?Voltage-output ports.
In Fig. 4:
-inner coil first paragraph replaces the coil that both positive and negative polarity is arranged;
-inner coil second segment replaces the coil that both positive and negative polarity is arranged;
-be arranged in inner coil bottom left and the front end inner coil electric current input electric wire wire that is connected;
-be arranged in inner coil bottom left and the front end inner coil electric current output electric wire wire that is connected;
-be arranged in right side, the inner coil bottom wire that is connected with front end inner coil electric current input electric wire;
-be arranged in right side, the inner coil bottom wire that is connected with front end inner coil electric current output electric wire.
In Fig. 6:
-outer coil first paragraph replaces the coil that both positive and negative polarity is arranged;
-outer coil second segment replaces the coil that both positive and negative polarity is arranged;
-be arranged in the outer coil bottom left wire that is connected with rear end outer coil current return electric wire;
-be arranged in outer coil bottom left and the rear end outer coil electric current output electric wire wire that is connected;
-be arranged in right side, the outer coil bottom wire that is connected with rear end outer coil electric current output electric wire;
-be arranged in right side, the outer coil bottom wire that is connected with rear end outer coil electric current current return electric wire.
In Fig. 7: the longitudinal ultrasonic guided wave of 15-incident; The 16-flaw echo; The 17-transmitted wave; The 18-crack.
In Fig. 8: 19-is the AC signal to the fixed frequency of inputting in current feedback circuit by signal generation apparatus.
In Fig. 9: rail damage detection apparatus mechanical part in 20-the present invention.
In Figure 10: first first defect default in flange of rail seat part position of 21-; Second first defect default in flange of rail seat part position of 22-; The 3rd first defect default in flange of rail seat part position of 23-.
In Figure 11: the initial induction electromotive force of 24-oscillograph recording; The feedback-induced electromotive force of defect 23 correspondences of 25-oscillograph recording; The feedback-induced electromotive force of defect 22 correspondences of 26-oscillograph recording; The feedback-induced electromotive force of defect 21 correspondences of 27-oscillograph recording; The induction electromotive force that 28-end reflections signal is corresponding.
Embodiment
Below in conjunction with embodiment and accompanying drawing, the present invention is described in further detail, but embodiments of the present invention are not limited to this.
Embodiment 1
A kind of rail damage detection apparatus based on magnetostriction and longitudinal ultrasonic guided wave, it has the detection distance, and detection time is short, detects in real time in contactless track detection vehicle on-line operation, and can find the advantage such as rail infant cracking damage.Its mechanical part as shown in Figure 1.The rectangular parallelepiped that its outward appearance is a lower ending opening, lower ending opening position shape is similar to the shape of rail rail head, will be slightly than rail greatly to guarantee the noncontact of itself and rail; Top is connected with track detection vehicle.It comprises interior layer line holder 2, inner coil 3, outer layer line holder 4, outer coil 5, yoke 6, permanent magnet 7, shell 8, current input terminal mouth 9, electrical inner layer coil current input electric wire 10, inner coil electric current output electric wire 11, outer coil electric current output electric wire 12, outer coil current return electric wire 13, Voltage-output port 14, specifically as shown in Figure 2.Interior layer line holder 2 is positioned on shell 8 and fixes.Inner coil 3 is positioned in interior layer line holder 2, and is connected with inner coil electric current input electric wire 10, inner coil electric current output electric wire 11 and current input terminal mouth 9, and method of attachment as shown in Figure 3.As shown in Figure 4, inner coil 3 is divided into some sections alternately both positive and negative polarity coils to its circuit theory, and the present embodiment is illustrated as three sections,
the section and
alternately arrange, in inner coil 3 lower ends, 4 wires, line are arranged
with leading portion end layer line loop current input electric wire 10, be connected, line
with inner coil electric current output electric wire 11, be connected, two electric wires are connected with current input terminal mouth 9.The position of putting according to electric current input and output electric wire, each section coil alternative current direction.That is: first paragraph coil
right-hand member and line
connect line
be connected 10, left end and line with inner coil input electric wire
connect line
be connected with inner coil electric current output electric wire 11 again, realize that electric current conducts from right to left, wherein dotted arrow represents the first paragraph coil
direction of current conduction; The second segment coil
left end and line
connect line
with inner coil input electric wire 10, be connected again, right-hand member and line
connect line
be connected with inner coil electric current output electric wire 11 again, realize that electric current conducts from left to right, in figure, solid arrow represents the second segment coil
middle direction of current; The 3rd section coil and first paragraph coil
the same, for repeating the first paragraph connection method.As shown in Figure 2, outer layer line holder 4 is placed on interior layer line holder 2 edges, makes the external layer line holder 4 in edge of interior layer line holder 2 play a supporting role.Outer coil 5 is arranged in outer layer line holder 4, as shown in Figure 5, and is connected 14 with rear end outer coil electric current output electric wire 12, outer coil current return electric wire 13 and back segment voltage sensor, as shown in Figure 6.Outer coil 5 itself does not pass into electric current, and it can produce induction electromotive force in coil because of changes of magnetic field, its be divided into some sections alternately the both positive and negative polarity coil (be illustrated as three sections,
the section and
alternately arrange), circuit connecting method alternate coils section the same as the method for attachment of inner coil and wire
and coil segment
middle electric current is positive and negative.The physical circuit method of attachment as shown in Figure 5.In figure, solid line represents the outer coil section
direction of current, dotted line represents the outer coil section
in direction of current.As shown in Figure 2, inner coil 3 is realized insulated separation by outer layer line holder 4 with outer coil 5.The inboard edge with outer layer line holder 4 of yoke 6 fixes, and by the edge of outer layer line holder 4, it is played to supporting function; Simultaneously, yoke 6 both sides, bottom are placed on shell 8 both sides of the edge, bottom, and by both sides of the edge, shell bottom, it are played to fixing and supporting role.Permanent magnet 7 is pasted mutually with yoke 6, to realize magnetic property.Simultaneously, permanent magnet 7 tops and shell 8 inboards, top fix, and by shell 8, it are realized to constraint.In addition, described current input terminal mouth 9 and Voltage-output port 14 are fixed on the two ends on top, the shell outside respectively, as shown in Figure 1.
It is worth mentioning that, inner coil 3 in this equipment schematic diagram and the wire thickness of outer coil 5 and density degree are only signal, real winding wire is compact arranged, the diameter of wire is encouraged and is accepted frequency and the wavelength decision of ultrasonic guided wave signals by it, in addition every section alternately the width of both positive and negative polarity coil be half of supersonic guide-wave wavelength, in Fig. 4
the section and
in section, Fig. 6
the section and
half of Duan Junwei supersonic guide-wave wavelength.Wire can be the hard coils such as enameled wire, can be also the soft circuit lines such as winding displacement of printed circuit board (PCB).
A kind of rail damage detecting method based on magnetostriction and longitudinal ultrasonic guided wave based on said apparatus, at first the external signal generator produces to detect and uses signal, by wire, signal is input to the current input terminal mouth of this equipment from the signal output port of signal amplifier after amplifying, inner coil produces a dynamic magnetic field according to the variation of input signal, with the magnetic field of permanent magnet generation, be coupled simultaneously, inspire along the supersonic guide-wave of rail longitudinal propagation, once supersonic guide-wave runs into the rail defect, can pass a defect reflection signal back, this defect reflection signal is converted to the alternating magnetic field of this frequency, this alternating magnetic field inspires induction electromotive force in outer coil.
Specifically comprise the following steps:
(1) calculate the dispersion curve of rail by GUIGUW software according to rail model and sectional dimension, select to be applicable to the guided wave centre frequency of the type rail supersonic guide-wave damage check according to dispersion curve;
(2) produce one by waveform generator and detect required electric signal, this electric signal waveform is consistent with detection guided wave waveform and centre frequency; This electric signal is imported to power amplifier, electric signal is amplified;
(3) as shown in Figure 9, electric signal after amplifying is entered to inner coil through the current input terminal mouth, in inner coil each section alternately the both positive and negative polarity coil produce the dynamic magnetic field of corresponding frequencies in rail under the electric signal effect, the quiescent biasing magnetic field that this magnetic field and permanent magnet produce is coupled, make the magnetized state of object to be detected that the variation under this frequency occur, make on the object to be detected longitudinal size and change, it is magnetostrictive strain, thereby the excitation ultrasound guided wave, supersonic guide-wave is along the rail longitudinal propagation.Now, outer coil produces an induction electromotive force corresponding with encouraged supersonic guide-wave by magnetostrictive back wash effect.This induction electromotive force is by the output of Voltage-output port.Voltage-output port and external signal treatment facility, as oscillographic signal input port connects by wire, record size and the generation time of initial induction electromotive force, as signal in Figure 11 24 by the external signal treatment facility;
(4) set in advance defect on rail in the present embodiment, as shown in figure 10, once the supersonic guide-wave along the rail longitudinal propagation runs into the rail defect, can pass a defect reflection signal back, utilize magnetostrictive back wash effect, can produce an identical alternating magnetic field of frequency with it in outer coil, this alternating magnetic field inspires another feedback-induced electromotive force corresponding with the defect reflection guided wave in outer coil.This feedback-induced electromotive force is by the output of Voltage-output port.Voltage-output port and external signal treatment facility, as oscillographic signal input port connects by wire, record size and the generation time of feedback-induced electromotive force by the external signal treatment facility, as the signal 25,26,27 in Figure 11;
(5) owing to there being following funtcional relationship between induction electromotive force and ultrasonic guided wave signals intensity:
Wherein k is the supersonic guide-wave wave number, the number of turn that n is receiving coil, and the cross-sectional area that s is receiving coil, the length that l is receiving coil, d is the axial distance between receiving coil and drive coil; ν is supersonic guide-wave velocity of wave in ferromagnetic material, μ
rfrom being the ferromagnetic material relative permeability, λ is the ferromagnetic material magnetostriction constant, H
0it is the function of coil turn and electric current.
Can determine the quantitative relationship between the intensity of the size of induction electromotive force and supersonic guide-wave by this formula; Intensity conversion by initial induction electromotive force and feedback-induced electromotive force is also measured the intensity of defect reflection guided wave signals, thereby can determine the big or small degree of damage.Simultaneously, can determine the quantitative relationship between ultrasonic guided wave signals intensity and rail defect size according to the stress wave principle; And the time that induction electromotive force produces is poor with the time life period of excitation guided wave, this mistiming be guided wave in rail, propagate and run into defect reflection after pass the time that excites position back.Therefore, can indirectly measure the time and intensity that the defect reflection guided wave signals produces by this induction electromotive force of apparatus measures, thereby determine the position of damage and the size of damage.
In the present embodiment, in described step (1), the detection signal of generation is the 10 cycle sinusoidal electric signals that centre frequency is the modulation of 375KHz Hanning window.Adopting the rail length of test use in step (4) is 2 meters.Adopt each defective locations after these apparatus and method are tested to be: the defect 1 at flange of rail bearing position is 1.65 meters apart from the guided wave transmitting terminal.The defect 2 at flange of rail bearing position is 1.1 meters apart from the guided wave transmitting terminal.The defect 3 at flange of rail bearing position is 0.55 meter apart from the guided wave transmitting terminal.By the position of contrast testing result Figure 11 and actual Embedded defect, sufficient proof the method can realize accurate location defect, and error is only grade., from monitoring result Figure 11, can find out, 2 meters whole testing processes of long rail are 0.1 millisecond of used time only, as seen efficient the and pinpoint accuracy of this detection method simultaneously.
Above-described embodiment is preferably embodiment of the present invention; but embodiments of the present invention are not restricted to the described embodiments; other any do not deviate from change, the modification done under Spirit Essence of the present invention and principle, substitutes, combination, simplify; all should be equivalent substitute mode, within being included in protection scope of the present invention.
Claims (3)
1. the rail damage detecting method based on magnetostriction and longitudinal ultrasonic guided wave, it is characterized in that, at first the external signal generator produces to detect and uses signal, be input to the current input terminal mouth after amplifying, inner coil produces a dynamic magnetic field according to the variation of input signal, with the magnetic field of permanent magnet generation, be coupled simultaneously, inspire along the supersonic guide-wave of rail longitudinal propagation, once supersonic guide-wave runs into the rail defect, can pass a defect reflection signal back, this defect reflection signal is converted to the alternating magnetic field of this frequency, this alternating magnetic field inspires induction electromotive force in outer coil, indirectly measure according to this induction electromotive force the time and intensity that the defect reflection guided wave signals produces, thereby determine the position of damage and the size of damage.
2. the rail damage detecting method based on magnetostriction and longitudinal ultrasonic guided wave according to claim 1, is characterized in that, specifically comprises the following steps:
(1) calculate the dispersion curve of rail according to rail model and sectional dimension, select the guided wave centre frequency of the type rail supersonic guide-wave damage check according to dispersion curve;
(2) produce one by waveform generator and detect required electric signal, this electric signal waveform is consistent with detection guided wave waveform and guided wave centre frequency; Then this electric signal is imported to power amplifier, electric signal is amplified;
(3) electric signal after amplifying is entered to inner coil through the current input terminal mouth, in inner coil each section alternately the both positive and negative polarity coil produce the dynamic magnetic field of corresponding frequencies in rail under the electric signal effect, the quiescent biasing magnetic field that this magnetic field and permanent magnet produce is coupled, make the magnetized state of object to be detected that the variation under this frequency occur, make on the object to be detected longitudinal size and change, it is magnetostrictive strain, thereby excitation ultrasound guided wave, supersonic guide-wave is along the rail longitudinal propagation, simultaneously, outer coil produces an initial induction electromotive force corresponding with encouraged supersonic guide-wave by magnetostrictive back wash effect, this initial induction electromotive force outputs to the external signal treatment facility by the Voltage-output port, the external signal treatment facility records size and the generation time of this initial induction electromotive force,
(4) once there be supersonic guide-wave to run into the rail defect, can pass a defect reflection signal back, utilize magnetostrictive back wash effect, can produce an identical alternating magnetic field of frequency with it in outer coil, this alternating magnetic field inspires a feedback-induced electromotive force corresponding with the defect reflection guided wave in outer coil, this feedback-induced electromotive force outputs to the external signal treatment facility by the Voltage-output port, and the external signal treatment facility records size and the generation time of this feedback-induced electromotive force;
(5) according to the relational expression of induction electromotive force and ultrasonic guided wave signals intensity, initial induction electromotive force and the size of feedback-induced electromotive force and the quantitative relationship between induction electromotive force and ultrasonic guided wave signals intensity, intensity conversion by initial induction electromotive force and feedback-induced electromotive force is also measured the intensity of defect reflection guided wave signals, thereby determines the big or small degree of damage; Determine the quantitative relationship between ultrasonic guided wave signals intensity and defect size according to the stress wave principle, simultaneously, mistiming between the time of the induction electromotive force that the time of the induction electromotive force that the defect reflection signal recorded by equipment produces and excitation supersonic guide-wave produce, with the distance of determining that supersonic guide-wave is propagated in rail, thereby obtain the accurate location that defect exists.
3. the rail damage detecting method based on magnetostriction and longitudinal ultrasonic guided wave according to claim 2, is characterized in that, has following funtcional relationship in step (5) between induction electromotive force and ultrasonic guided wave signals intensity:
Wherein k is the supersonic guide-wave wave number, the number of turn that n is receiving coil, and the cross-sectional area that s is receiving coil, the length that l is receiving coil, d is the axial distance between receiving coil and drive coil, ν is supersonic guide-wave velocity of wave in ferromagnetic material, μ
rfor the ferromagnetic material relative permeability, λ is the ferromagnetic material magnetostriction constant, H
0the function of coil turn and electric current, V
r(k, t) is ultrasonic guided wave signals intensity, and t is the time, and w is supersonic guide-wave center circle frequency, w=2 π f, the centre frequency that wherein f is supersonic guide-wave; The induction electromotive force that E is the coil two ends; ξ is an integral parameter, and its scope is between [0, l]; J is imaginary part; K in jk ξ also refers to the supersonic guide-wave wave number.
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