CN1169777A - Contaminant detection system - Google Patents
Contaminant detection system Download PDFInfo
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- CN1169777A CN1169777A CN 95196773 CN95196773A CN1169777A CN 1169777 A CN1169777 A CN 1169777A CN 95196773 CN95196773 CN 95196773 CN 95196773 A CN95196773 A CN 95196773A CN 1169777 A CN1169777 A CN 1169777A
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Abstract
A contaminant detection system (100, 410, 800, 830) includes a transmitter (102, 122, 422, 442, 472, 516, 716, 736, 737, 810, 838, 846) for transmitting a guided wave (128, 420) through the skin (114, 422, 440, 470, 520, 532, 710, 712, 730, 732, 754, 816, 832, 846) at particular resonances, wherein each resonance point utilized will have propagation characteristics sensitive to a condition of interest. A contaminant (770, 834) may then be classified by transmitting several resonances and then carrying out appropriate feature extraction and pattern recognition techniques utilizing a host processor (134).
Description
The present invention relates to the contaminant detector, particularly utilization comes device that the contaminant on the aircraft surfaces is surveyed and classified at the different polarization guided wave of realizing multiple resonance on the dispersion curve.
Under some condition of work, aircraft is subjected to the damage of contaminant accumulation on external component surface or the casing easily.The example of this class contaminant comprises ice, ethylene glycol, oil or fuel.As not adding detection, the then accumulation of some contaminant (especially ice) thus finally might make aircraft cause undesirable state of flight because of the loading of impost changes wing structure.Therefore, detect the ability of the accumulation of contaminant on this surface and the ability of this class contaminant classification just become very important so that differentiate dangerous state of flight.
A large amount of different types of contaminant detectors have been used for this purpose.Comprising ultrasonic contaminant detector, it utilizes the ultrasonic energy that passes aircraft or wing shell.
A kind of so ultrasonic ice sheet detector has been described in the United States Patent (USP) 4,461,178 of Jacques R.Chamuel (Chamuel).According to this patent, a supersonic signal generator is added to output on the transducer, converts signal energy to ultrasound wave, makes it pass part wing shell, is detected by second transducer again.The waveform of transmission comprises a part of wave of compression and a part of flexural wave.The initial waveform that this receiving transducer receives is corresponding to pass the wave of compression that the wing shell sends from the source transducer.Follow after the wave of compression, stronger peak value is corresponding to receiving the first time of passing the flexural wave that the wing shell sends.Ice sheet on aerofoil surface will influence signal waveform, and flexural wave component wherein will be decayed, and wave of compression remains unchanged substantially.The wave of compression that receives provides the indication of accumulating corresponding to ice sheet with the ratio of the peak amplitude of flexural wave part.
When adopting the Shu Jili transducer of Chamuel routine, the signal that is difficult to the control transmission becomes a kind of specific pattern and waveform, because this class transducer has the trend of generation near the higher phase velocity of cutoff frequency.Therefore, very difficult will ice with the pool with the system of Chamuel separates.As previously mentioned, wish very and ice and pool branch can be come that because the ice sheet of accumulation is dangerous to flying, and the water of accumulation is unimportant.
Another kind of ultrasonic ice sheet detector has been described in people's such as Watkins United States Patent (USP) 4,604,612.People such as Watkins utilize to send and receiving transducer, and wherein transmitter sends out the shear wave pulse of the horizontal polarization of propagating by the wing shell, its wavelength and sheet metal thickness comparability, thereby this shear wave can be by surface conductive.If the surface is dry, or be coated with water (horizontally polarized shear can not be propagated therein), then the pulse height of Jie Shouing covers ice sheet (shear wave can be propagated therein) Shi Yaoda with specific surface.This is because some energy of shear wave pulse will dissipate because of the propagation by ice sheet.Therefore, people's such as Watkins ice sheet detector can detect the ice sheet that is attached to the surface, but insensitive to the existence of water.
The same with the system of Chamuel, to detect with people's such as Watkins system that to cover skim ice sheet waterborne be impossible.Floating ice waterborne also is a kind of state of danger concerning flight.
Therefore, wish to have very much a kind of ultrasonic system reliably discriminated union distinguish various multi-form wing contaminants, particularly water and the formation of ice.
The purpose of this invention is to provide a kind of ultrasonic contaminant detection system that can differentiate various different contaminant types.
Press one aspect of the present invention, contaminant detection system comprises a kind of method that the not clear contaminant of body structure surface is classified of being used for, this method comprises the step that the response of the known contaminant of multiple difference on the body structure surface is surveyed and drawn, comprise that the different tuning-pointss by structure pass the steps such as received signal that this structure sends multiple acoustic bearing ripple, receives these ripples and form every kind of contaminant state of indication, said here forwarding step carries out every kind of known contaminant state on the body structure surface;
The received signal that is passed in its surface by the different tuning-pointss of structure and has the structure of unknown contaminant to send multiple conducted acoustic waves, receive these sound waves and form every kind of contaminant state of indication; And
The received signal of the unknown contaminant of the indication received signal with the known contaminant state of indication is compared and unknown contaminant is classified.
Press another aspect of the present invention, a kind of being used for comprises that to the method that the contaminant on the shell is classified passing shell by the first transmission tuning-points sends first guided wave, receives described first guided wave and provide indication its steps such as first received signal;
Passing casing by the second transmission tuning-points that is different from the first transmission tuning-points sends second guided wave, receives described second guided wave and provides indication its second received signal;
The signal and the predefined test signal of described first and second receptions are compared.
By one side more of the present invention, contaminant detection system comprises the device that is used for to the classification of the contaminant on the shell, comprising:
One is used for passing the transmitter that shell sends first guided wave by the first transmission tuning-points, and is used for passing the transmitter that shell sends second guided wave by the second transmission tuning-points;
One is used for receiving first guided wave and provides indication its first received signal, and receives second guided wave and the receiver of its second received signal of indication is provided; And
One is used for signal processor that first and second received signals and the test signal that sets in advance are compared.
The present invention utilizes special transmission tuning-points to realize the discriminating of multiple contaminant.Obtain the very strong power that penetrates in this way, thereby the detection sensitivity of various different contaminant states is improved.In addition, the present invention can be convenient to packing, is easy to make, and also is easy to safeguard.
To the detailed description that embodiment did, these and other targets of the present invention, characteristic and advantage will be more clear and definite by accompanying drawing.
Fig. 1 is the theory diagram by contaminant detection system of the present invention.
Fig. 2 shows the phase velocity of conducting by metal chassis and the relation curve of frequency-thickness product.
Fig. 3 is the signal amplitude of receiving transducer reception from the system that constitutes by the present invention and the relation curve of frequency.
Fig. 4 a-4c is that the U that 4 tuning-pointss of dispersion curve Mode6 gained shown in Figure 2 are drawn with respect to normalization casing thickness and the normalized amplitude of W particle displacement distribute.
Fig. 5 a passes the typical energy pulse diagram that casing sends by invention.
Fig. 5 b passes the delta function energy pulse diagram that casing sends by invention.
Fig. 6 a is from the guided wave received signal amplitude that passes 0.087 inch thick no contaminant aluminium sheet and the relation curve of frequency.
Fig. 6 b is from the guided wave received signal amplitude that passes 0.087 inch thick water contaminant aluminium sheet and the relation curve of frequency.
Fig. 6 c is from the guided wave received signal amplitude that passes 0.087 inch thick ice contaminant aluminium sheet and the relation curve of frequency.
Fig. 6 d is from the guided wave received signal amplitude that passes 0.087 inch thick ethylene glycol contaminant aluminium sheet and the relation curve of frequency.Relation curve with frequency.
Fig. 7 is the transmitter circuitry theory diagram that is used for by contaminant detection system of the present invention.
Fig. 8 is the receiver circuit theory diagram that is used for by contaminant detection system of the present invention.
Fig. 9 is the transducer location configuration principle block diagram that is used for by contaminant detection system of the present invention.
Figure 10 is another embodiment theory diagram by the transmission part of contaminant detection system of the present invention.
Figure 11 is the another embodiment theory diagram by the transmission part of contaminant detection system of the present invention.
Figure 12 is the embodiment theory diagram again by the transmission part of contaminant detection system of the present invention.
Figure 13 a is used for by the transducer of contaminant detection system of the present invention and another embodiment three-dimensional view of coupling mechanism.
Figure 13 b is the side view of transducer shown in Figure 13 a and coupling mechanism.
Figure 14 is the process flow diagram that contaminant detection system of the present invention is used for collecting the contaminant grouped data.
Figure 15 a is the top view by another embodiment of contaminant detection system of the present invention.
Figure 15 b is the side view of contaminant detection system shown in Figure 15 a.
Figure 16 a is the top view by the another embodiment of contaminant detection system of the present invention.
Figure 16 b is the side view of contaminant detection system shown in Figure 16 a.
Figure 17 a is the top view of an embodiment again by contaminant detection system of the present invention.
Figure 17 b is that contaminant detection system shown in Figure 17 a is along the amplification profile of 17b-17b.
Figure 18 is the side view by another embodiment of contaminant detection system of the present invention.
Figure 19 is the side view by another embodiment of contaminant detection system of the present invention.
Figure 20 is the received signal amplitude and the time relation curve of contaminant detection system shown in explanation Figure 18 and 19.
Now, comprise transmitter section 102 and receiver section 104 by contaminant detection system 100 of the present invention referring to Fig. 1.Transmitter section 102 sends the casing 114 that has accumulated contaminant 118 on the surface 115 that ultrasonic guided waves (representing with ripple bag 128) pass its exposure.Essential Terms to guided wave comprise plane wave, comb shape ripple, symmetrical wave, wave of compression, asymmetrical wave and flexural wave.
Transducer 110,112 can be any of many known ultrasonic probes, is the piezoelectric probe of SWS8 such as Krautkramer Branson product type.The diameter of transmitting transducer 110 should be the twice of casing thickness at least, preferably three times.The bandwidth of transducer should be wide as far as possible, so that can make an arrowband excitation function in big frequency range interscan.
Receiving unit 104 comprises a receiving transducer or pops one's head in 112, is used for the ultrasound-transmissive conversion of signals is fed on the transmission line 132 for the corresponding electric signal that receives.Probe 112 passes through coupling wedge 130 with incident angle B and casing 114 acoustic couplings.Angle B is as the function of multiple factor and determine, such as casing thickness or the like.For the casing of a constant thickness, angle B should be approximately equal to transmitting probe incident angle A.
Coupling mechanism 116,130 can be made of any suitable ultrasound-transmissive material, such as organic glass or other acrylate copolymers.
Now, in dispersion curve, provide the multi-mode feature and the multiple different value of wave speed of guided wave referring to Fig. 2.Guided wave is the diffusing elastic wave of propagating along casing of rich shade, and many vibration resonance points are arranged.Dispersion curve represents to allow the natural resonance (or ripple propagation attitude) propagated in structure.On behalf of a kind of natural resonance or ripple, indicated every curve or pattern propagate attitude in dispersion curve.Provided in the metal chassis and propagated attitude (pattern 1-12) for 12 kinds of a specific wavelength or frequency-thickness product (fd) different ripples.
The incident angle A (see figure 1) of transmitting probe and phase velocity of wave functional dependence.Therefore, a fixing transmitting probe incident angle has just been set a special phase velocity value, and represents with horizontal line on dispersion curve.A pair of horizontal line 152,156 is as the illustration of tuning-points on the dispersion curve of two different incidence angles.The incident angle of line 152 is less than the incident angle of line 156.
Now referring to Fig. 3, curve shows is from by the received signal amplitude of receiving transducer the institute of the present invention construction system and the relation of frequency.The signal of transmission has a plurality of frequency components and constant phase velocity.Four peak values seeing on curve are represented four the tuning-points R1-R4s of ultrasonic energy with the lowest loss transmission.These peak values are corresponding to the tuning-points R1-R4 on the dispersion curve shown in Figure 2.It is to be noted that these four some R1-R4 obtain on four different mode lines (Mode2-Mode5) of Fig. 2.
Referring to Fig. 2 and 3, the existence of surface contaminants may change amplitude, frequency and the phase velocity characteristic (or feature) of tuning-points on Fig. 3 curve (for example putting R1-R4).The particular characteristics that changed and change amount thereof can be described as this tuning-points to sensitivity that specific contaminant had.Have been found that some tuning-points is responsive especially to ice sheet, and insensitive to water and/or ethylene glycol or other contaminants.Such sensitivity may appear at along extracting any place that these characteristics also are used as the entire spectrum of Figure recognition contaminant sorter input signal.On the other hand, some tuning-points is very responsive to ethylene glycol, and insensitive to water and/or ice or other contaminants.The variation that other tuning-pointss present wave property to different mixtures and other contaminants of ice/water/ethylene glycol.By special selection, might produce the little excitation region of special penetration depth and sensory characteristic to transmission phase velocity and frequency.Every kind of structure will have the unique tuning-points that satisfies this class preferred characteristics.The applicant finds when analyzing several suitable tuning-points simultaneously, might differentiate and classifies the kinds of surface contaminant.No matter adopting theoretical modeling still is that experimental technique all can be discerned these points.By surveying and drawing out the response of ad hoc structure to different contaminants, may develop provide as the master controller system of specialized system based on the characteristic of being extracted, characteristic than and the sorting algorithm of suitable reference value., it is to be noted because detection system, structure to be detected and the changeableness of contaminant itself are not impossible words even will encourage accurate tuning-points, also be unpractical for this reason.Therefore, in enforcement of the present invention, must encourage less relatively excitation area.The garden 150 that in Fig. 2, is the picture shade with such region representation.The excitation of zonule is guaranteed the excitation of tuning-points and is provided the grouped data of usefulness.For reaching this purpose, preferably center on the tuning-points considered to encourage less than the frequency bandwidth of 0.5MHz mm with less than the phase velocity bandwidth of 0.5mm/s.
For example, can utilize a plurality of tuning-pointss that structure is detected with same phase velocity.Therefore each point has the single-frequency thickness product.How the same phase velocity of line 152 explanations of Fig. 2 provides a plurality of tuning-pointss.One or more such points can satisfy the requirement of system sensitivity.How 154 same frequency-thickness product of explanation of the line of Fig. 2 are used for the different tuning-points of a plurality of phase velocities.Can encourage different tuning-pointss along these two line sweeps, eliminate the variable between measuring therefrom.On the other hand, can programme amplitude, phase velocity and the frequency when changing each the measurement as previously mentioned and saltus step between tuning-points to detection system of the present invention.No matter the excitation order how, the tuning-points of each use all will have the propagation characteristic to institute's consideration state sensitivity.By sending several times resonance, carry out rational signal extraction and Figure recognition then and handle, can classify to contaminant.
Also can be by particle movement to the description of guided wave:, be called polarization coplanar displacement (U) (promptly being parallel to the casing surface) a) along the particle wave motion of direction of wave travel with two vector components; Or b), is called not coplanar displacement of polarization (W) (promptly perpendicular to the casing surface) perpendicular to the particle wave motion of direction of wave travel.These displacement functions can be formulated as the function of in the generation of dispersion curve resulting eigenwert or phase velocity value.The W displacement is very sensitive to the detection of water because when guided wave when casing is propagated, the existence of W displacement causes the leakage in liquid, thereby wave-amplitude is reduced greatly.On the other hand, the U displacement is insensitive to water.Otherwise U and W displacement are all very sensitive to the detection of ice, because the both causes absorption or energy leakage in ice sheet.
Having U and W displacement (being called different polarization or many polarized waves here) guided wave transmission combination, that contain many vector components on the casing exposed surface may be more effective and more useful to providing further contaminant to classify.For example, can adopt waveform with the intimate U of equating and W surface displacement.Special contaminant may make the big high attenuation of such waveform, thereby additional classified information is provided.In addition, can change the frequency of waveform and/or phase velocity (as previously mentioned) to extract further classified information.
Now referring to Fig. 4 a-4c, wherein the normalized amplitude of U and W particle displacement distributes and is that 4 tuning-pointss to Mode6 gained in the dispersion curve shown in Figure 2 draw with respect to normalization casing thickness.It is to be noted, these points only as an example, and wave structure all changing along the every place of dispersion curve, changes any state or system parameter and all can produce different wave structures.The top line 157 of each figure (being that the normalization one-tenth-value thickness 1/10 is 0.5) is represented the exposed surface of casing.Therefore, represent in the particle movement at the interface of casing surface/contaminant in the displacement at this place.Simultaneously, though the normalization displacement signs in 0.1 from-0.1, the absolute value of displacement (not being actual value) is significant number.Can see that from Fig. 4 a-4d the U displacement is symmetrical about casing center 158, and the W displacement is antisymmetric.
Now referring to Fig. 4 a, the U and the W particle displacement normalized amplitude of wherein illustrating for about 5.2 fd value distribute.Can see, approach zero in the U of surface displacement, and the W displacement be about 0.6.Therefore, this tuning-points on the Mode6 curve has the not coplanar displacement component of the advantage of occupying.
Now referring to Fig. 4 b, the U and the W particle displacement normalized amplitude of wherein illustrating for about 7.58 fd value distribute.Can see, approach zero in the W of surface displacement, and the U displacement be about 1.0.Therefore, this tuning-points on the Mode6 curve has the coplanar displacement component of the advantage of occupying.
Now referring to Fig. 4 c, the U and the W particle displacement normalized amplitude of wherein illustrating for about 9.1 fd value distribute.Can see that from the teeth outwards U displacement and W displacement are about 0.7.Therefore, this tuning-points on the Mode6 curve has the intimate displacement vector component that equates, or does not have the coplane or the not coplanar displacement component of the advantage of occupying.
Tuning-points shown in Fig. 4 c may have the sensitivity that the contaminant other contaminants that can not discern except tuning-points shown in ice and water or Fig. 4 a and the 4b is provided the contaminant classified information of usefulness.Certainly, the practicality of these points is decided by multiple factor, such as case material, wing structure, casing thickness or the like.
Now, those of skill in the art be it is evident that: by in advance with regard to various known contaminants to experimentizing or Theoretical Calculation with the issuable influence of guided wave that special tuning-points or resonance region send by specific casing, just might classify to contaminant, and or by the saltus step between different mode on the dispersion curve, or rest on the single-mode, all can change the characteristic of guided wave.Providing contaminant and wavy attitude (frequency, pattern, waveform, amplitude, vector component or the like) the sensitiveest, the most useful response can be stored in the neural network.A kind of specialized system then can be used to various guided wave waveforms casing be carried out ultrasonic simulation, and the contaminant of reality is carried out real-time grading.
Referring to Fig. 5 a, the typical case who is provided by the radiating circuit 122 by the present invention sends the shaped pulse that signal is a kind of diagram.Each pulse preferably has 4-50 cycle on the single-frequency in the 0.2MHz-20MHz frequency range.It is to be noted that other waveforms also can adopt.For example, pulse can have different shapes, one side of pulse or another side is become tiltedly, or be asymmetric.
Referring to Fig. 5 b, can adopt another kind of transmission pulse is the spike-shaped pulse that is close to the delta function.This impingement driving pulse can produce multi-mode and transmit simultaneously, even be not all critical dispersion curve tuning-pointss of phase velocity lines such as edge.The signal that receives then will offer master controller, infer transmission information with fast Fourier transform (FFTs) or other digital signal processing methods.The multi resonant that the receives guided wave that shakes will be similar to curve shown in Figure 3.Then, just can analyze and contaminant is classified whole frequency characteristic or specific characteristic (such as the Feng Hegu on the curve).Since the pulse of delta function is a kind of high energy pulse, perhaps laser instrument is desirable emissive source.
Now, illustrate the amplitude-frequency relation curve of four received signals of receiving transducer from the system that is similar to configuration shown in Figure 1 referring to Fig. 6 a.The casing that the signal transmission is passed through is without any contaminant.Nearly about 26.2 ° of the incident angle of transmitting transducer.The signal that sends is the sweep signal from 0-2.5MHz mm.The peak value 160-163 of curve is corresponding to send angle (the being phase velocity) mathematical point on the dispersion curve when frequency is crossed curved scanning down in same incident.In Fig. 2, illustrate that with a horizontal line (for example line 152 or 156) by a given frequency range signal being scanned is the most clearly under a specific incident angle.Amplitude peak 160-163 is corresponding to the intersection point of horizontal scanning line with the theoretical dispersion curve of different tuning-pointss.For example, Fig. 2 center line 152 is crossing with the theoretical dispersion curve of pattern 2,3,4,5,6 and 8 in the fd of 0-12MHz mm scope.Peak value 160-163 among Fig. 6 a is corresponding to 0-2, in the 5MHz mm scope and the similar intersection point under 26 ° of incident angles.
Now, wherein provide the curve that is similar to Fig. 6 a, but casing is subjected to water contaminant in various degree referring to Fig. 6 b.Line 170 expressions are from the signal of the casing reception of the about 45gm of water accumulating volume.Line 172 expressions are from the signal of the casing reception of the about 250gm of water accumulating volume.Line 174 expressions are from the signal of the casing reception of the about 500gm of water accumulating volume.Can see that from Fig. 6 b the decay of received signal is decided by the water accumulating volume on the casing.
Now, wherein provide the curve that is similar to Fig. 6 a, but casing is subjected to ice contaminant in various degree referring to Fig. 6 c.Line 180 expressions are from the signal of the casing reception of the about 35gm of accumulated ice amount.Line 182 expressions are from the signal of the casing reception of the about 250gm of accumulated ice amount.Line 184 expressions are from the signal of the casing reception of the about 500gm of accumulated ice amount.Can see that from Fig. 6 c the decay of received signal is decided by the deposition iced on the casing.
Now, wherein provide the curve that is similar to Fig. 6 a, but casing is subjected to ethylene glycol contaminant in various degree referring to Fig. 6 d.The signal that the casing of the about 35gm of the line long-pending amount of 190 expression ethylene glycol receives.Line 192 expressions are from the signal of the casing reception of the about 250gm of the long-pending amount of ethylene glycol.Line 194 expressions are from the signal of the casing reception of the about 500gm of the long-pending amount of ethylene glycol.Can see that from Fig. 6 d the decay of received signal is decided by the deposition of ethylene glycol on the casing.
Now, be used for providing the transmitter 122 of electrical energy pulse to comprise a numerically-controlled oscillator (NCO) 210, be used for presenting the sinusoidal waveform of characteristic frequency to transmission line 212 to transducer 110 referring to Fig. 7.The frequency of NCO210 can change to 10MHz from about 100KHz.NCO210 is controlled by transmission line 216 by microprocessor (CPU) 214.CPU214 is controlled by transmission line 136 by primary processor.Oscillator 216 provides clock signal through transmission line 218 to CPU214.Transmission carrier frequency waveform on the transmission line 212 is fed to a modulator 220, signal is modulated into the energy envelope pulse delivers to impact damper 226 through transmission line 224, again the pulse energy envelope signal that slows down is delivered to transmitting transducer 110 by transmission line 228.Modulator 220 is controlled by transmission line 230 by D/A transducer 232.D/A transducer 232 obtains input signal by data line 236 from pulse envelope storage unit 238.Pulse envelope table memory 238 is subjected to the control of configurable logic array (CLA) 240 by data line 232.Configurable logic array (CLA) 240 is subjected to the control of CPU214 by data line 244.Configurable logic array (CLA) 240 also receives the output envelope data by transmission line 236 provides feedback data to deliver to CPU214 through transmission line 246.CLA240, pulse envelope storage unit 238 and D/A transducer 232 are formed envelop generator, the sinusoidal waveform of presenting through transmission line 212 from NCO210 is modulated, and presented energy pulse with characteristic frequency to transmission line 224.250 pairs of pulse length, pulse shape and pulse-response amplitudes that send waveform of envelop generator are controlled.Pulse length can be controlled to more than the 30ns.Pulse-response amplitude can be set to one of 255 non-zero power level output set-points.Controlled the shaping energy pulse that allows to produce a given carrier frequency by time function paired pulses amplitude.The control of this paired pulses length and pulse shape provides the control to the spectrum composition that sends waveform.
Now referring to Fig. 1 and 8, be sent to Hi-pass filter 310 by transmission line 132 from the electric signal output of receiving transducer 112.Signal through filtering is sent to the selectable increase level of being made up of many amplifiers 316,318,320 and multiplexer 322 314 through transmission line 312.A plurality of joints of transmission line 330,332,334,336 are linked the multiplexer 322 by CPU214 (by transmission line 324) control.Be fed to Analogue mixer 342 through multiplexer 322 amplifying signals by transmission line 340.Analogue mixer 342 is with transmission line 340 received signal that transmits and the sinusoidal waveform combination of being sent here through transmission line 344 by NCO346 (it is controlled by transmission line 348 by CPU214).The intermediate-freuqncy signal that produces is sent to the adjustable Hi-pass filter 352 of clock from frequency mixer 342 by transmission line 350, and this Hi-pass filter is regulated through the clock signal that transmission line 354 provides by NCO356 (it is controlled by transmission line 358 by CPU214).The output of Hi-pass filter 352 is sent to clock tunable low pass filter 362 through transmission line 360, and this low-pass filter is regulated through the clock signal that transmission line 364 provides by NCO366 (it is controlled by transmission line 368 by CPU214).Wave filter 352 and 362 comprises a bandpass filter.The filtering signal that obtains is sent to rectifier 372 through transmission line 370.Signal after rectification is sent to a pair of same integrators 376,378 with the operation of 50% degree of overlapping through transmission line 374.The output of integrator 376,378 is sent to sampler 384 respectively through transmission line 380,382, and sampler is alternately switched these two signals and will be exported through transmission line 386 and be sent to D/A transducer 388.Integrator 376,378 and sampler 384 are controlled by CLA390 by transmission line 392,394,396 respectively.The numeral output sampling of D/A transducer 388 is delivered to CLA390 by transmission line 398.These data are collected by CPU214 by transmission line 399 and storage finishes up to listening at interval.Listening to end at interval, CPU214 returns data result to principal computer through transmission line 136.
Utilize NCO346 to provide numerically controlled sine wave to control the local oscillator frequencies that frequency mixer 342 uses.Just provide control by NCO210 control transmission frequency and by NCO346 control local oscillating frequency to intermediate frequency.
NCO356 and NCO366 are used in combination so that low pass and high pass filter function to be provided with wave filter 352 and 362.The bandpass filter of utilizing these two wave filters formation bandwidth and centre frequency to be easy to control.When sending the change of burst spectrum composition, receiver can be configured to the signal to noise ratio (S/N ratio) minimum by suitable adjustment receiver bandwidth.
Also be easy to integral time change.The general pulse length of selecting to equal integral time to be used as the transmission pulse.Its objective is and in an integration period, from a given pulse, collect energy as much as possible.The ability that this parameter is changed into different value just provides a kind of means that pulse prolongs situation that are adapted to.
Listening to is another variable that is easy to change at interval.How many integrator samplings are this value determine will collect before sending the result back to principal computer 134.This parameter will be determined the pulse repetition rate of system with sending pulse length.
CPU214 preferably communicates by a RS232 serial communication interface and a principal computer 134 that is operated in 19.2kpbs.Principal computer is provided with following parameter by the instruction of sending from communication interface: the transmitter oscillator frequency; Send signal envelope; The mixing oscillator frequency; The low-pass filter corner frequency; Listen at interval; Send pulse length; Receiver gain; The Hi-pass filter corner frequency; And integral time.In case after the above-mentioned parameter regulation, pulse can produce and collect the number of signals strong point of reception.Then, these data being returned primary processor 134 handles.Primary processor then can be determined at time of arrival of listening to the interim measured signal and peak value thereof.If necessary, the gain that can change CDS100 is also measured again.
Measurement can be carried out on the single-frequency of narrow bandwidth easily.Can set up a frequency spectrum with many unifrequent measurements.Initial frequency, termination frequency and frequency step all are under the control of principal computer 134.
Now referring to Fig. 9, contaminant detection system of the present invention comprises 6 element of transducers 412,413,414,415,416,418.Guided wave by arrow 420 expressions can transmit between element, covers the zone of being considered on the wing 422 therefrom.Therefore, this configuration can cover the wing area bigger than the system that only uses two transducers.Certainly, any different configuration and combination thereof can be adopted.For example, when transmitted wave becomes fan cut, can use single transducer 412 to send to a plurality of transducer 413-415.
Now referring to Figure 10, an alternative embodiment of the invention comprises with pectination and is configured in a plurality of transducer 430-437 on the casing 440.Transmitter 442 drives these transducers by transmission line 444-451.This method can be by selecting best tuning-points to produce the phase velocity and the frequency values of selection on the dispersion curve.These transducers can contain or be installed in the common metal shield 452.
Now referring to Figure 11, an alternative embodiment of the invention comprise with the array type structural arrangements with the coupling mechanism 474 of 470 one-tenth presetting angles of casing on a plurality of transducer 460-466.Transmitter 472 drives these transducers by transmission line 474-480.Control these transducers by time time-delay figure and just change phase velocity effectively by effective incident angle variation.Particularly when the distance between transmitter and receiver was very little, a kind of possible embodiment can be made of a non-contacting ultrasonic transmitter and a capacitor type receiving transducer.Another kind of noncontact excitation or receive perhaps available electromagnetic transducer (EMAT) or even the laser pulse transducer produce guided wave.
With opposite, also can adopt a kind of pulse impact type system with the continuous transmission of a transmitter and a receiver.A transducer can be used as transmitter and receiver simultaneously, thereby might form edge reflections, and this depends on detected structure, and even surveys wherein ultrasonic energy and leak and it is rebooted the thin metal bar shaped or the flat waveguide of prescribed direction.
Transmitter 442 among Figure 10 and 11 and 472 can change selects produce pulse at special time for which type of transducer.Produce order and other parameters of pulse by the type that changes pulse, selected transducer and transducer, can obtain the different tuning-pointss on the dispersion curve.For example, can obtain different effective incident angles by every transducer of continuous startup and the time-delay that changes between the subsequent pulses.Equally, also serially, side by side or by certain other order make each other transducer produce pulse.Although it should also be noted that here only to provide eight or seven transducers respectively, also can adopt the transducer of different numbers.What it should also be noted that Figure 10 and 11 shows is transmitting transducer, and receiving unit also can constitute one and be similar to the transducer array that sends array, or discrete component just simply.
Now referring to Figure 12, be included on the coupling mechanism 514 the different a pair of transducers 510,512 that angle C, D settle that preset with 508 one-tenth of casing 520 normals by an alternative embodiment of the invention.Transmitter 516 drives transducer by transmission line 518,519.Discovery is for 0.125 inch flat board, when angle C is about 26 °, when angle D is 38 ° of left and right sides, obtains the most effective contaminant data aggregation result.Certainly, also can adopt more than two transducer with plural different angles arrangement.
Now, comprise a shear wave transducer 530 that on coupling mechanism 532, presets E arrangement in angle with a particular azimuth F by an alternative embodiment of the invention with 534 one-tenth of casings referring to Figure 13 a and 13b.Except the guided wave pattern that in flat layer, exists, also have the time-harmonic wave motion of so-called shear level (SH) pattern.The meaning of horizontal this term of shear is that the particle vibration (displacement or speed) that is caused by any SH mould is in the plane that is parallel to laminar surface.How many projectile energies orientation (angle F) decision that transducer 530 is gone up on coupling mechanism 532 surfaces has enter the guided wave of generation, and shear level (SH) ripple that how much enters generation is arranged again.Since the SH mode is the synthetic of pure coplane shear wave, the tractive force that then is added to laminar surface also must have a not shear component of coplane.This realizes by viscous couplant (not showing out) is provided, such as add silicones or bonding agent between coupling mechanism 532 and casing 534.If transducer 530 is shear wave contact transducers, then the particle vibration in the coupling mechanism will be in x
1-x
3The plane.x
1And x
3The relative quantity of displacement will be the function of angle E and F.As angle F is 0, then the polarization direction of transducer and x
1Axle overlaps, and all projectile energy enters directed mode.When angle F increased, the energy distribution between guided wave and the SH mould equated in the time of angle F=45 °.For angle F 〉=72 °, the projectile energy that then enters the SH mould will be above 90%.Be the energy maximum that the SH mould is shared, angle F should be as far as possible near 90 °.Can see that angle F can not reach 90 °, so SH mould and guided modes can produce simultaneously.
Now referring to Figure 14, according to similar Fig. 1 but have the contaminant detection system of similar a pair of transmitting transducer shown in Figure 12, a process flow diagram that is used for collecting the contaminant grouped data comprises step 610, at this, by master controller the first pulsed frequency f is set
D1, the second pulsed frequency f
D2, the first pulse-response amplitude A
1, the second pulse-response amplitude A
2, the first pulse shape PS
1, the second pulse shape PS
2In step 612, it is f that master controller instructs first transmitting transducer to pass the casing transfer characteristic
D1, A
1, PS
1Guided wave.In step 614,616, the pulse of transmission is received by receiving transducer, again by master controller with its digitizing and store.In step 618, the amplitude new by master controller is set to A
1+NCheck at step 620 pair newly-increased amplitude, do not surpass predefined value A to prove it
1+XIf A
1+NBe not equal to A
1+X, then in step 612, send newly-increased frequency.If A
1+NEqual A
1+X, then the first transmission cycle sent out first shaped pulse of first phase velocity (incident angle by first transmitting transducer is determined).Then, in step 622, it is f that master controller instructs second transmitting transducer to pass the casing transfer characteristic
D2, A
2, PS
2Guided wave.In step 624,626, the pulse of transmission is received by receiving transducer, again by master controller with its digitizing and store.Check at step 628 pair amplitude, do not surpass predefined value Z to prove it.If amplitude has reached Z, master controller utilizes the data of collecting and storing in step 614,616,624 and 626, adopt fuzzy logic, neural network, fast Fourier transform, or known other digital processing methods of technician are classified contaminant.If amplitude is not equal to Z, then be set to A by the new amplitude of master controller in step 632
2+NCheck at step 634 pair newly-increased amplitude, do not surpass predefined value A to confirm it
2+YIf A
2+NBe not equal to A
2+Y, then in step 622, send newly-increased frequency.If A
2+NEqual A
2+Y, then the second transmission cycle is just with the inswept second frequency scope of second phase velocity (incident angle by second transmitting transducer is determined).Then, whether contaminant (if any) classification is decision making in step 636 pair.If contaminant is classified, then the result is shown in step 636, program promptly comes to an end.If contaminant is still unfiled, then by master controller the first new pulsed frequency f is set in step 640
D1, the second pulsed frequency f
D2, the first pulse-response amplitude A
1, the second pulse-response amplitude A
2, the first pulse shape PS
1, the second pulse shape PS
2, and in step 612 beginning another takes turns pulse transmission and contaminant detects and classification.
Should be noted that, by under first incident angle, sending the pulse of first frequency earlier, under second incident angle, send the pulse of second frequency then, pick out the different tuning-pointss on the casing dispersion curve therefrom, promptly can realize two different transmission tuning-pointss.
Now, comprise the contaminant check-out console 710,712 that is placed in wing 720 end faces by an alternative embodiment of the invention referring to Figure 15 A and 15B.Ultrasound emission probe 716 sends guided wave by coupling mechanism 714 and thin plate 710,712, is received by coupling mechanism 724 by receiving transducer 722 then.Probe 716,722 is respectively by transmission line 718,726 controls.Because wing has inconsistent thickness, slot, chemical annular knurl open region (Chemically milled cutout areas), other irregular forms, and assembled construction part (as pole, rivet or the like) in addition, just use the contaminant check-out console 710,712 that is placed in the wing end face eliminated many with directly transmit relevant problem by wing itself.All these wing features are to the damaging influence of the transmission of guided wave.The thickness of check-out console 710,712 is uniformly, thereby provides the blanket predictable transmission result of various aircrafts.In addition, when being damaged, this check-out console is easy to change.
Now, comprise the contaminant detecting plate 730,732 that is installed in wing 734 end faces by another kind of embodiment of the present invention referring to Figure 16 A and 16B.Ultrasonic probe 736,737 sends by coupling mechanism 738 and receives guided wave, and controls by transmission line 740.In this mode, only need a probe to carry out the contaminant classification.Probe 736 can be installed on the oval partial points or near it, so that more effectively utilize wave energy.Check-out console 730,732 is similar to the description of Figure 15 A and 15B, but its termination 739,738 and 740 rounded, oval or other shapes.Certainly the shape of termination will be decided by appropriate signal analysis.Preferably select oval termination for use, because equate by the entire path length that material returns probe again from probe.This means that the energy pulse that enters oval moulding aluminium sheet will return its whole energy simultaneously.
Check-out console 710,712,730,732 can be bonded in the wing end face, also availablely resembles methods of attachment such as rivet, screw, nuts and bolt and is fixed.Yet, should be pointed out that check-out console should isolate to obtain best result with aerofoil surface acoustics.Therefore, suggestion makes acoustics mistake coupling between two surfaces, in order to avoid make check-out console seem very thick on acoustics.Can adopt various bonding agents, polyfoam or cushion pad that these check-out consoles and wing acoustics are isolated.
Now, comprise an outer protection casing 750, be used for protecting the thin sensor 752 of the PVDF that is installed on the wing 754 by another kind of embodiment of the present invention referring to Figure 17 A and 17B.The thin sensor 752 of PVDF is made of top double-sided adhesive layer 756, sensing electrode 758, PVDF film 760, bottom sensing electrode 762 and bottom double-sided adhesive layer 764.Aspect 750,756,758,760,762 and 764 is set up a mechanical system that comprises quality, elasticity and damping performance effectively.By measuring mechanical system is modeled to the desired complex impedance of frequency function, just might classifies the contaminant that is deposited in the protection outer 750.Also may determine the deposition of contaminant.
Now referring to Figure 18, comprise a contaminant check-out console or a bar 816 that is installed on wing 818 end faces by the another kind of embodiment of contaminant detection system 800 of the present invention.Ultrasonic probe 810 sends and receives guided wave (by arrow 814 explanations) by coupling mechanism 812, and controls by transmission line 820.Check-out console 816 is also used as the waveguide of output and reflected energy.A plurality of PVDF thin film transducer 822-826 are installed in the one side of check-out console 816 non-exposures, to collect the energy leakage from check-out console 816 end face contaminants 828.Except being used for of being discussed before this obtained the decay and other characteristics of contaminant information, the PVDF transducer also provided the positional information of contaminant.
Should be pointed out that concerning embodiment shown in Figure 180, the test board of outside deposition contaminant is not essential.In other words, test board 816 also may be represented casing itself.Structure 818 then will be represented certain other potential wing structure.Therefore transducer 822-826 then directly is placed under the casing.
Now referring to Figure 19, comprise that by the another kind of embodiment of contaminant detection system 830 of the present invention one is collected contaminant 834 and is installed in contaminant check-out console or bar 832 on the wing 836.Ultrasonic probe 838 sends guided wave (by lines 840 expressions) by coupling mechanism 842, and controls by transmission line 844.Check-out console 832 is as the waveguide of output energy.Second block of plate or bar 846 are installed between collecting board 832 and the wing 836.Lath 846 is as the waveguide of reflected energy (by lines 848 expressions).Reflected energy is received by receiving transducer 850 by coupling mechanism 852.The electrical receive signal feedback is added on the transmission line 854.On lath 846, open a plurality of notches 856, be used for receiving the energy leakage and the reflection of contaminant 828, and energy is returned transducer 850.Except being used for of being discussed before this obtained the decay and other characteristics of contaminant information, notch 856 also provided the positional information of contaminant.
Should be pointed out that concerning embodiment shown in Figure 19 it is not essential being used for the lath of outside deposition contaminant of return signal.In other words, lath 846 also may be represented casing itself.Structure 836 then will be represented certain other potential wing structure.Therefore 856 in notch is opened among casing itself.
Now, wherein provide by the amplitude of contaminant detection system shown in aforementioned Figure 18 and 19 and the typical relation curve of time graph referring to Figure 20.Solid line 860 is represented the not desired curve of contaminant outside plate.Dotted line 862 expressions are subjected to the curve of contaminant outside plate.Can see that received signal descends at point 844,866.Since the group velocity of specific transmission mode is known, then can release from the time that amplitude descends in the contaminant position of point 844,866.
Though the invention has been described in conjunction with the embodiments and description, those skilled in the art are to be understood that and might make further and various other changes, omission or interpolation it, do not exceed the spirit and scope of the present invention.
Claims (14)
1. one kind is used for method that the unknown contaminant on mechanism surface is classified, may further comprise the steps:
Survey and draw out the response of structure to the known contaminant state of multiple difference of body structure surface, the different tuning-pointss that are included in structure pass the step that structure sends multiple acoustic bearing ripple, receives these ripples that pass unknown contaminant structure and form the received signal of every kind of known contaminant state of indication, and wherein said forwarding step carries out every kind of known contaminant state on the body structure surface;
Passing its surface at the tuning-points of structure has the structure of unknown contaminant to send multiple acoustic bearing ripple, receives these ripples, and the received signal that forms the unknown contaminant state of indication; And
The received signal of the unknown contaminant of indication is compared and unknown contaminant is classified with the known contaminant state of indication.
2. be used for method that unknown contaminant on the body structure surface is classified by claim 1, wherein the guided wave that sends under two kinds of situations has identical phase velocity.
3. be used for method that unknown contaminant on the body structure surface is classified by claim 1, wherein said step of passing unknown contaminant body structure surface transmission guided wave comprises transmitting transducer of running, the step that the guided wave of unknown contaminant body structure surface is passed in described reception comprises receiving transducer that is different from transmitting transducer of running
4. be used for method that unknown contaminant on the body structure surface is classified by claim 1, wherein saidly pass step that unknown contaminant body structure surface sent and received guided wave and comprise that one of running is used for the public transducer that sends and receive.
5. one kind is used for method that the contaminant on the shell is classified, comprises the steps:
Pass shell by the first transmission resonance and send first guided wave, receive described first guided wave, and provide indication its first received signal;
Pass shell by the second transmission resonance that is different from the first transmission resonance and send second guided wave, receive described second guided wave, and provide indication its second received signal;
Described first and second received signals and predefined test signal are compared.
6. be used for method that unknown contaminant on the body structure surface is classified by claim 5, wherein said guided wave sends with identical phase velocity.
7. be used for method that unknown contaminant on the body structure surface is classified by claim 5, wherein saidly pass the step that unknown contaminant body structure surface sends second guided wave and comprise transmitting transducer of running, the step that second guided wave of unknown contaminant body structure surface is passed in described reception comprises receiving transducer that is different from transmitting transducer of running.
8. be used for method that unknown contaminant on the body structure surface is classified by claim 5, wherein saidly pass step that unknown contaminant body structure surface sent and received guided wave and comprise that one of running is used for the public transducer that sends and receive.
9. one kind is used for method that the contaminant on the shell is classified, comprises the steps:
On shell, settle the contaminant check-out console;
Pass the contaminant check-out console by the first transmission resonance and send first guided wave, receive described first guided wave, and provide indication its first received signal;
Pass the contaminant check-out console by the second transmission resonance and send second guided wave, receive described second guided wave, and provide indication its second received signal;
Described first and second received signals and predefined test signal are compared.
10. be used for device that the contaminant on the shell is classified, comprise:
One is used for passing shell by first tuning-points and sends first guided wave and be used for passing the transmitter that shell sends second guided wave by second tuning-points;
One is used for receiving first guided wave and its first received signal of indication is provided and is used for receiving second guided wave and provides indication its receiver of second received signal; And
One is used for signal processor that first and second received signals and predefined test signal are compared.
11. be used for device that the unknown contaminant on the body structure surface is classified by claim 10, wherein said transmitter sends guided wave with identical phase velocity.
12. be used for device that the unknown contaminant on the body structure surface is classified by claim 10, wherein said transmitter sends guided wave by a transmitting transducer, receiver receives guided wave by a receiving transducer that is different from transmitting transducer.
13. be used for device that the unknown contaminant on the body structure surface is classified by claim 10, wherein said transmitter and receiver has public transducer.
14. be used for device that the contaminant on the shell is classified, comprise:
A contaminant check-out console that is installed on the shell;
One is used for passing the contaminant check-out console by first tuning-points and sends first guided wave and be used for passing the transmitter that the contaminant check-out console sends second guided wave by second tuning-points;
One is used for receiving first guided wave and its first received signal of indication is provided and is used for receiving second guided wave and provides indication its receiver of second received signal; And
One is used for signal processor that first and second received signals and predefined test signal are compared.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 95196773 CN1169777A (en) | 1994-12-13 | 1995-12-12 | Contaminant detection system |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/355,357 | 1994-12-13 | ||
| CN 95196773 CN1169777A (en) | 1994-12-13 | 1995-12-12 | Contaminant detection system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1169777A true CN1169777A (en) | 1998-01-07 |
Family
ID=5083256
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 95196773 Pending CN1169777A (en) | 1994-12-13 | 1995-12-12 | Contaminant detection system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1169777A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103185744A (en) * | 2011-12-30 | 2013-07-03 | 北京林业大学 | Detection device for measuring transmission time of ultrasonic waves in sheet material |
| TWI686618B (en) * | 2018-11-23 | 2020-03-01 | 行政院原子能委員會核能研究所 | Single probe type nonlinear ultrasonic detecting device and method thereof |
-
1995
- 1995-12-12 CN CN 95196773 patent/CN1169777A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103185744A (en) * | 2011-12-30 | 2013-07-03 | 北京林业大学 | Detection device for measuring transmission time of ultrasonic waves in sheet material |
| TWI686618B (en) * | 2018-11-23 | 2020-03-01 | 行政院原子能委員會核能研究所 | Single probe type nonlinear ultrasonic detecting device and method thereof |
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