CN110687208A - Non-reference Lamb wave damage monitoring method based on hyperbolic positioning - Google Patents
Non-reference Lamb wave damage monitoring method based on hyperbolic positioning Download PDFInfo
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
Abstract
The invention provides a no-reference Lamb wave damage monitoring method based on hyperbolic positioning, which comprises the following steps: arranging a rhombic piezoelectric excitation/sensing array on a structure to be tested; piezoelectric sensors on a diagonal line are selected as excitation sources to excite excitation signals of a single Lamb wave mode, and a pair of piezoelectric sensors on the other diagonal line is selected to acquire structural response signals; repeating the steps for the rest piezoelectric sensors on the diagonal line, obtaining the time difference of the damage scattering signals corresponding to the structural response signals, and determining the positive and negative of the time difference; and calculating the damage position and the approximate range by adopting a hyperbolic curve positioning method. The Lamb wave damage monitoring method has the advantages of simple array form, fewer numbers and simple experimental measurement operation, and realizes the detection and monitoring of the structural damage by utilizing the hyperbolic damage positioning principle under the condition of not needing a reference signal, so the Lamb wave damage monitoring method is not influenced by the change of the structure and the external condition, and the accuracy of the structural damage monitoring is improved.
Description
Technical Field
The invention belongs to the field of structural health monitoring, and particularly relates to a non-reference Lamb wave damage monitoring method based on hyperbolic positioning, which is used for positioning imaging research of damage.
Background
With the increasing requirements on the safety and reliability of the structure, the online monitoring and diagnosis of the structural damage increasingly draws high attention, and in order to prevent the disaster or loss caused by the structural damage, the structural damage must be effectively monitored. The plate-shaped structure is one of the main forms of major engineering structures, and the real-time online structural health monitoring is greatly regarded. Lamb waves are elastic waves which propagate in a solid plate-shaped structure under the condition of a free boundary, and the Lamb waves have great advantages on large-area nondestructive detection of the plate-shaped structure due to small attenuation, long propagation distance and sensitivity to tiny damage in the structure, so that the damage monitoring technology based on active Lamb waves is a research hotspot for health monitoring of the plate-shaped structure at present.
Most of active Lamb wave damage monitoring methods are based on a reference signal, namely, a response signal in a structural health state is used as the reference signal, and the response signal in the current state is subtracted from the reference signal, so that the structural damage condition is obtained.
However, since the acquisition time of the reference signal is different from that of the current response signal, the external conditions during acquisition, such as ambient temperature, structural boundary and stress conditions, and external vibration, will generally change, and the internal conditions, such as the performance of the sensor itself, will also be affected by the temperature and other factors, so that the damage scattering signal is easily submerged in the signal change and noise caused by the change of the internal and external conditions of the structure, which not only makes it difficult to obtain an accurate result for damage detection, but also affects the real-time performance of on-line monitoring. In addition, when acquiring the reference signal, if there is already a damage in the structure, the monitoring method based on the reference signal cannot extract the damage scattering signal generated by the damage, and thus cannot obtain a correct damage monitoring result.
To overcome the defects of the conventional active Lamb wave damage detection method based on a reference signal, a plurality of researchers have studied the non-reference active Lamb wave damage detection technology by using various methods. The existing Lamb wave damage detection technology such as time reversal [ Wangqiang, Yanxiujun, Chenxiahui, Baili ], "non-reference Lamb wave time reversal damage probability imaging monitoring method", (Instrument and Meter Notification), "34 (07) stage, 149 + 155 page ], Bayesian theory [ Dutao, muao, Wangxiang ]," non-reference signal active Lamb wave damage positioning method based on Bayesian theory ", (vibration engineering Notification)," 30(01) stage in 2017, 33-40 page ], and the like, realizes non-reference Lamb wave damage positioning monitoring.
2016 Lidongshen et al discloses a probability-based Lamb wave baseline-free damage identification method [ Lidongshen, golden union, probability-based Lamb wave baseline-free damage identification method ], Fujian construction science and technology, 2016-31 +34, the disclosed method adopts a pulse-echo mode distributed active sensing network to collect signals, extracts time characteristics of damage scattering signals through a time window function and continuous wavelet transformation, and finally utilizes a hyperbolic probability imaging algorithm to perform damage positioning and imaging, thereby realizing Lamb wave baseline-free damage identification. The method also adopts a hyperbolic probability imaging algorithm to carry out non-reference structure damage positioning imaging. However, the existing non-reference active Lamb wave damage monitoring method usually needs more piezoelectric elements to form a dual-element piezoelectric sensing array, wherein every two sensors which are very close to each other are respectively used as an excitation sensor and a receiving sensor to eliminate direct sensing signals and highlight damage scattering signals, and optionally two receiving sensors form a receiving probe pair for calculating a hyperbolic track, so that the number of the required sensors is large, the signal processing and calculation are very complex, and the performance requirement on a monitoring system is high.
Therefore, there is a need to find a method for monitoring damage of non-reference Lamb waves, which has a simple arraying manner, a small number of devices, and simpler and more convenient signal processing.
Disclosure of Invention
The invention aims to provide a no-reference Lamb wave damage monitoring method based on hyperbolic positioning so as to realize no-reference active Lamb wave damage positioning and monitoring.
In order to solve the above problems, the present invention provides a no-reference Lamb wave damage monitoring method based on hyperbolic positioning, which includes:
s1: arranging a rhombic piezoelectric excitation/sensing array on a structure to be detected according to the size of a required monitoring area;
s2: selecting one piezoelectric sensor on one diagonal line of the rhombic piezoelectric excitation/sensing array as an excitation source, exciting an excitation signal of a single Lamb wave mode in a structure to be tested, simultaneously selecting a pair of piezoelectric sensors on a straight line vertical to the diagonal line as receivers, and respectively acquiring a pair of structure response signals corresponding to the current excitation source;
s3: sequentially taking the rest piezoelectric sensors on the diagonal line as excitation sources, respectively repeating the step S2, and acquiring a plurality of pairs of structure response signals corresponding to different excitation sources;
s4: acquiring the time difference of a pair of damage scattering signals corresponding to each pair of structural response signals; and qualitatively judging the order of arrival by respectively observing respective damage scattered signals in each pair of structural response signals, thereby determining the positivity and negativity of the time difference and further judging the distance between the damage position and a pair of piezoelectric sensors serving as receivers.
S5: calculating to obtain the damage position and the approximate range by adopting a hyperbolic positioning method, wherein the method comprises the following steps:
s51: calculating a damage scattering distance difference according to the time difference obtained in the step S4 and the group velocity c of the excitation signal propagating in the structure to be measured; obtaining hyperbolic traces according to the scattering distance difference of the damage, and calculating by combining all the hyperbolic traces to obtain the damage position;
s52: performing micro-unit division on a monitoring area of the structure to be detected, establishing a coordinate matrix and a corresponding image matrix, and performing pixel assignment on each element in the image matrix according to a probability density function to obtain a damage positioning focused image; and then, positioning and imaging the approximate range of the damage position according to the coordinates of each piezoelectric sensor of the excitation/sensing array and the damage position obtained in the step S51, so as to realize accurate positioning and monitoring of the damage.
In step S1, the rhombic piezoelectric excitation/sensing array is composed of 4S piezoelectric sensors, S +1 piezoelectric sensors are respectively disposed on each side of the piezoelectric excitation/sensing array, and S is a positive integer.
In step S1, the piezoelectric excitation/sensing array is composed of 4 piezoelectric sensors, and the piezoelectric excitation/sensing array is square.
In step S2, the excitation signal of the single Lamb wave mode is applied to the excitation source through an ultrasonic narrowband signal generated by a signal generator via a power amplifier, and is excited by adjusting the frequency; the structural response signals are acquired by acquiring signals received by the receiver through a digital oscilloscope and entering a computer.
In step S2, the excitation signal is a sinusoidal signal or a window function modulated sinusoidal signal.
Preferably, the excitation signal is a sinusoidal signal modulated with a hanning window.
The step S4 includes:
s41: normalizing all the structure response signals acquired in the steps S2 and S3 to eliminate errors caused by performance differences of the piezoelectric sensors;
s42: and respectively carrying out difference subtraction on each pair of normalized structural response signals, according to the theorem of the perpendicular bisector, mutually canceling the direct sensing signals in the structural response signals after the difference subtraction, thereby separating to obtain a pair of damage scattering signals, and determining the time difference of the pair of damage scattering signals according to the time points corresponding to the respective signal peak values of the pair of damage scattering signals.
Preferably, in the step S4, the time difference Δ t between the pair of lesion scatter signalsiABComprises the following steps:
ΔtiAB＝tiA-tiB，
wherein, tiAAnd tiBRespectively, a piezoelectric sensor P as an excitation sourceiTo a pair of piezoelectric sensors P as receiversA，PBI is the ordinal number of the piezoelectric sensor as an excitation source, and a and B are the ordinal numbers of the piezoelectric sensor as a receiver, respectively; when i is 1 to 4, if i is 1 or 3, a is 2, B is 4, if i is 2 or 4, a is 1, and B is 3;
and in said step S4, when Δ t is greater thaniABWhen negative, the damage position is close to the A-th piezoelectric sensor PAFar from the Bth piezoelectric sensor PB(ii) a When Δ t is reachediABFor the right time, the damage position is far away from the A-th piezoelectric sensor PANear the Bth piezoelectric sensor PBWhen Δ t isiABWhen the damage position is 0, the damage position is located at the a-th piezoelectric sensor PAWith the B-th piezoelectric sensor PBOr no damage is caused in the structure to be tested.
The non-reference Lamb wave damage monitoring method based on hyperbolic positioning adopts the existing piezoelectric sensor to realize a rhombic array with mutually vertical diagonals, and the piezoelectric sensor positioned on one diagonal line is selected as an excitation source to excite the excitation signal of a single Lamb wave mode, a pair of piezoelectric sensors in a line perpendicular to the diagonal act as receivers to acquire structural response signals, so that the array has simple form and fewer number, the experimental measurement operation is simple, and by utilizing the hyperbolic damage positioning principle, the detection and monitoring of the structural damage are realized without reference signals, so the influence caused by the change of the structure and external conditions is avoided, the accuracy of the structural damage monitoring is improved, and a large amount of structural response signal data and complex signal processing and calculating steps are not needed, and the method has good engineering application operability. In addition, the Lamb wave damage monitoring method realizes the separation of damage scattering signals and direct sensing signals under the excitation of active Lamb waves by signal normalization and signal differencing, and highlights the information of the damage scattering signals.
Drawings
Fig. 1 is a schematic diagram of a piezoelectric excitation/sensing array used in a hyperbola-based positioning reference-free Lamb wave damage monitoring method according to an embodiment of the invention.
Fig. 2 is a schematic diagram of a piezoelectric excitation/sensing array used in a hyperbola-based positioning reference-free Lamb wave damage monitoring method according to another embodiment of the invention.
Fig. 3A-3B are schematic diagrams of excitation signals of a single selected Lamb wave mode of a hyperbola-based positioning reference-free Lamb wave damage monitoring method according to an embodiment of the invention, wherein fig. 3A shows a time domain waveform of the excitation signals of the single Lamb wave mode, and fig. 3B shows a frequency domain waveform of the excitation signals of the single Lamb wave mode.
Fig. 4A-4D are structural response signals acquired by the piezoelectric excitation/sensing array shown in fig. 1, where fig. 4A and 4B respectively show structural response signals acquired when the first piezoelectric sensor is used as an excitation source and the second and fourth piezoelectric sensors are used as receivers, and fig. 4C and 4D respectively show structural response signals acquired when the second piezoelectric sensor is used as an excitation source and the first and third piezoelectric sensors are used as receivers.
Fig. 5A-5B are damage scattering signals obtained by normalizing the structural response signals and subtracting the difference between every two structural response signals shown in fig. 4A-4D, respectively, where fig. 5A shows a pair of damage scattering signals obtained by normalizing the structural response signals of the second and fourth piezoelectric sensors and subtracting the difference between the normalized structural response signals, and fig. 5B shows a pair of damage scattering signals obtained by normalizing the structural response signals of the first and third piezoelectric sensors and subtracting the difference between the normalized structural response signals and the difference between the normalized structural response signals.
Fig. 6 is a diagram of the monitoring result of the damage localization imaging in the structure to be measured.
Detailed Description
The present invention will be further described with reference to the following specific examples. It should be understood that the following examples are illustrative only and are not intended to limit the scope of the present invention.
The invention provides a no-reference Lamb wave damage monitoring method based on hyperbolic positioning, which comprises the following steps of:
step S1: as shown in fig. 1, a rhombic (preferably square, square is a special rhombic) piezoelectric excitation/sensing array is arranged on a structure to be detected according to the size of a required monitoring area;
in the present embodiment, the piezoelectric excitation/sensing array is composed of 4 piezoelectric transducers P, as shown in FIG. 1i(i is 1,2,3,4), the structure to be measured is an aluminum plate structure, and the size is 200 multiplied by 100 multiplied by 1mm3Taking the center of the plate structure as the origin of coordinates, the coordinates of each piezoelectric sensor of the piezoelectric excitation/sensing array are respectively the first piezoelectric sensor P1(100,10), a second piezoelectric sensor P2(60,50), third piezoelectric sensor P3(100,90), fourth piezoelectric sensor P4(140,50) in mm, a first piezoelectric sensor P1And a third piezoelectric sensor P3Diagonal line of the second piezoelectric sensor P2And a fourth piezoelectric sensor P4The diagonal lines are perpendicular to each other. The damage in the experimental measurements is typically via hole damage with a diameter of 5mm and a centre of the circle position of (80,50) in mm.
In addition, in other embodiments, the piezoelectric excitation/sensing array may also be composed of 4s piezoelectric sensors, s is a positive integer, and s +1 piezoelectric sensors distributed at equal intervals are respectively arranged on each side (including a vertex) of the rhombic piezoelectric excitation/sensing array, for example, a piezoelectric excitation/sensing array composed of 12 piezoelectric sensors as shown in fig. 2. Therefore, the geometric characteristic of the piezoelectric excitation/sensing array is that the diagonals are perpendicular to each other, and the positive and negative piezoelectric effects of the piezoelectric transducer are utilized for exciting and receiving ultrasonic Lamb waves. In experimental measurement, the piezoelectric sensor is directly adhered to the same side surface of a structure to be measured through instantaneous setting adhesive.
Step S2: selecting a piezoelectric sensor P located on a diagonal of the diamond-shaped piezoelectric excitation/sensing arrayi(i ═ 1,2,3,4) as an excitation source, exciting an excitation signal of a single Lamb wave mode in the structure to be measured, and selecting a pair of piezoelectric sensors P on a straight line perpendicular to the diagonal lineA，PBAs a receiver, a pair of structural response signals f corresponding to the current excitation source are respectively acquirediA，fiBWherein the excitation signal of the single Lamb wave modePreferably, the excitation signal of the single S0 mode, i is the ordinal number of the piezoelectric sensor as the excitation source, and a and B are the ordinal numbers of the piezoelectric sensor as the receiver, respectively. For example, when the piezoelectric excitation/sensing array is composed of 4 piezoelectric sensors, i.e., s is 1 and i is 1 to 4, if i is 1 or 3, a is 2 and B is 4, and if i is 2 or 4, a is 1 and B is 3; in addition, when the piezoelectric excitation/sensing array is composed of 12 piezoelectric sensors, i.e., s is 3, i is 1,4,7,10, if i is 1 or 7, a is 2, and B is 12, as shown in fig. 2; a is 3, B is 11; a is 4, B is 10; a is 5, B is 9; and a is 6, B is 8; if i is 4 or 10, a is 3, B is 5; a is 2, B is 6; a is 1, B is 7; a is 12, B is 8; and a is 11 and B is 9.
In this embodiment, the excitation signal is a hanning window modulated 5-cycle sinusoidal signal with a center frequency of 250kHz, and the time domain waveform and the frequency domain waveform are shown in fig. 3A and fig. 3B, respectively. In addition, the excitation signal can also be a sinusoidal signal modulated by other window functions, such as a heiveseidel step function, or a sinusoidal signal can be directly adopted. But generally, the excitation signal is a sinusoidal signal modulated by a hanning window, so that the signal energy is more concentrated and the waveform change is more stable.
For example, as shown in fig. 4A and 4B, when i is 1, that is, the first piezoelectric sensor P is ready to be used1As an excitation source, a second piezoelectric sensor P2And a fourth piezoelectric sensor P4A pair of structural response signals f acquired when respectively used as receivers12、f14Time domain diagram of (a). Wherein the structural response signal f12、f14Both can be divided into a direct sensing signal and a damage scattering signal, wherein the direct sensing signal is a signal with a relatively large peak value of the first wave packet and a relatively clear waveform, and the damage scattering signal is a signal with a relatively small peak value of the subsequent wave packet, as shown in fig. 4B, the direct sensing signal and the damage scattering signal are clearly separated, but sometimes the two signals are overlapped with each other. The pair of structure response signals f shown in FIG. 4A and FIG. 4B12、f14The direct sensing signals in the sensor are basically consistent, and the damage scattering signals are obviously different, which shows that the damage exists in the structure to be measured, and the damage position does not existAt the second piezoelectric sensor P2And a fourth piezoelectric sensor P4On the perpendicular bisector of the diagonal; as shown in fig. 4C and 4D, when i is 2, that is, the second piezoelectric sensor P is ready to be used2As an excitation source, a first piezoelectric sensor P1And a third piezoelectric sensor P3A pair of structural response signals f acquired when respectively used as receivers21、f23The pair of structural response signals f21、f23No obvious difference indicates that the structure to be measured has no damage or the damage position is located in the first piezoelectric sensor P1And a third piezoelectric sensor P3On the perpendicular bisector of the diagonal, and simultaneously responds to the signal f according to the previous pair of structures12、f14Can preliminarily determine that the damage position is located at the first piezoelectric sensor P1And a third piezoelectric sensor P3On the mid-vertical line of the diagonal.
Thereby, the piezoelectric sensor P as an excitation sourceiAnd a pair of piezoelectric sensors P as receiversA，PBConstructed as a set of monitoring channels. The hardware part used by the detection method of the invention is the same as the hardware part of the traditional method monitoring system, and generally comprises the following parts: computer, signal generator, power amplifier, digital oscilloscope and various connecting wires. The single Lamb wave mode excitation signal is loaded on the excitation source after passing through an ultrasonic narrow-band signal generated by a signal generator through a power amplifier, and is excited by adjusting the frequency; the structural response signals are acquired by acquiring signals received by the receiver through a digital oscilloscope and entering a computer. The sampling frequency was set to 25 MHz.
Further, the step S2 further includes: acquiring the structural response signal fiA，fiBThe group velocity c of the excitation signal propagating in the structure to be measured is calculated according to the linear distance (known) between the excitation source and the receiver, and the group velocity is assumed to be constant before and after the damage.
Step S3: and (4) sequentially taking the rest piezoelectric sensors on the diagonal line as excitation sources, respectively repeating the step S2, and acquiring a plurality of pairs of structural response signals corresponding to different excitation sources so as to acquire the structural response signals of the whole monitoring area.
Step S4: acquiring a time difference between a pair of damage scattering signals corresponding to each pair of structural response signals, specifically comprising:
step S41: normalizing all the structure response signals acquired in the steps S2 and S3 to eliminate errors caused by performance differences of the piezoelectric sensors;
the normalization process is performed using the following formula:
wherein x (t) is the structural response signal, Max is the maximum value of the structural response signal x (t), and y (t) is the normalized structural response signal.
Step S42: respectively carrying out difference subtraction on each pair of normalized structural response signals, according to the theorem of the perpendicular bisector, mutually canceling direct sensing signals in the structural response signals after subtraction, thereby obtaining a pair of damage scattering signals through separation, and determining the time difference delta t of the pair of damage scattering signals according to the time points corresponding to the respective signal peak values of the pair of damage scattering signalsiAB(ii) a I.e., Δ tiAB＝tiA-tiBWherein, tiAAnd tiBRespectively, a piezoelectric sensor P as an excitation source1To a pair of piezoelectric sensors P as receiversAAnd PB(including the A-th piezoelectric sensor PAWith the B-th piezoelectric sensor PB) I is the ordinal number of the piezoelectric sensor as the excitation source, a and B are the ordinal numbers of the piezoelectric sensor as the receiver, and when i is 1 to 4, if i is 1 or 3, a is 2, B is 4, and if i is 4
2 or 4, a ═ 1 and B ═ 3.
For example, as shown in fig. 5A, a first piezoelectric sensor P is provided1As an excitation source, a second piezoelectric sensor P2And a fourth piezoelectricSensor P4The signals are respectively used as structural response signals (i.e. i is 1, A is 2, B is 4) acquired by a receiver, the signals are normalized and subjected to difference subtraction to eliminate direct sensing signals to obtain a pair of damage scattering signals, and the time difference delta t of the pair of damage scattering signals can be determined according to the time points corresponding to the signal peak values of the pair of damage scattering signalsiAB(ii) a As shown in fig. 5B, the second piezoelectric sensor P is disposed2As an excitation source, a first piezoelectric sensor P1And a third piezoelectric sensor P3When the signals are respectively used as receivers, structural response signals (i.e. i is 2, A is 1, and B is 3) are collected, direct sensing signals can be eliminated by subtracting differences after normalization, the signals are found to tend to be stable and fluctuate up and down at the position of 0, and the time difference delta t of a pair of damage scattering signals can be preliminarily determinediAB0, and the damage position is located at the first piezoelectric sensor P1And a third piezoelectric sensor P3On the mid-vertical line of the diagonal.
Further, the step S4 further includes: qualitatively judging the order of arrival by observing the respective damage scattering signals in each pair of structural response signals, thereby determining the time difference Δ t between the pair of damage scattering signals in the step S4iABAnd then determines the respective distances of the damage positions from the piezoelectric sensor P as a receiverA，PBDistance (c) to (d). Therefore, the damage position can be determined on which one of the two symmetrical hyperbolas is specific, the damage position can be determined on a certain hyperbola track, and the accurate damage position can be obtained by eliminating the false images.
Wherein, the time difference Δ t between the pair of lesion scattering signals in the step S4iABWhen negative, it indicates that the damage position is close to the A-th piezoelectric sensor PAFar from the Bth piezoelectric sensor PB(ii) a Time difference delta t of scattering signal when damageiABWhen the damage position is positive, the damage position is far from the A-th piezoelectric sensor PANear the Bth piezoelectric sensor PBWhen the time difference Δ t of the scattering signal is damagediABWhen the damage position is 0, the damage position is located at the a-th piezoelectric sensor PAWith the B-th piezoelectric sensor PBOn the perpendicular bisector of the connecting line, orAnd the structure to be tested has no damage, wherein i is the ordinal number of the piezoelectric sensor as an excitation source, A and B are the ordinal numbers of the piezoelectric sensors as receivers, and when i is 1-4, if i is 1 or 3, A is 2, B is 4, and if i is 2 or 3, A is 1, and B is 3.
For example, as shown in FIG. 4A, the lesion scatter signal is not significant, indicating overlap with the direct sensor signal; as shown in fig. 4B, the lesion scatter signal is significant, illustrated behind the direct sense signal; thus, the damage scattering signal reaches the second piezoelectric sensor P first2And then to the fourth piezoelectric sensor P4Thereby determining the time difference DeltatiABLess than 0(i ═ 1, a ═ 2, and B ═ 4); and is determined by the time difference Deltat124When the damage position is less than 0, the damage position is close to the second piezoelectric sensor P2Far from the fourth piezoelectric sensor P4. Furthermore, as can be seen from the above description with respect to fig. 5B, the time difference Δ t between a pair of lesion scatter signalsiAB0, and the damage position is described to be located at the first piezoelectric sensor P1And a third piezoelectric sensor P3On the mid-vertical line of the diagonal.
Step S5: and calculating to obtain the position and the approximate range of the damage by adopting a hyperbolic positioning method, and analyzing and judging the health condition of the structure to be detected.
The step S5 specifically includes:
step S51: according to the time difference delta t of the pair of injury scattering signals in the step S4iABAnd calculating the damage scattering distance difference Δ d according to the group velocity c of the excitation signal propagating in the structure to be measured in the step S2iABI.e. Δ diAB＝c×ΔtiAB(ii) a Scattering distance difference Deltad according to a plurality of damagesiABAnd obtaining a plurality of hyperbolic tracks, and calculating by combining all the hyperbolic tracks to obtain the damage position.
Specifically, according to the geometrical knowledge, a set of points where the difference between the distances to a pair of fixed points is a fixed value is a hyperbola, whereby the scattering distance difference Δ d according to each lesion can be obtainediABAnd a pair of piezoelectric sensors P corresponding theretoAAnd PBObtaining a pair of hyperbolic traces, a plurality of differences of scattering distances Δ diABA plurality of pairs of hyperbolic traces are obtained, and the position where the intersection point of all the hyperbolic traces is the largest can be determined as the lesion position.
Thus, step S51 has determined the damage location of the structure under test from a mathematical geometric formula.
Step S52: carrying out micro-unit division on a monitoring area of the structure to be detected, establishing a coordinate matrix and a corresponding image matrix, enabling each element in the image matrix to represent one micro unit in the structure to be detected, and carrying out pixel assignment on each element in the image matrix according to a probability density function to obtain a damage positioning focusing image; and then, according to the coordinates of each piezoelectric sensor in the excitation/sensing array and the damage position obtained in the step S51, positioning and imaging the approximate range of the damage position, so as to accurately position and monitor the damage.
Here, the difference Δ d in scattering distance of the damageiABIn order to obtain a hyperbolic trace in a mathematical and geometric sense, the probability density function represents the probability density that a coordinate point is a damage location. The closer to the hyperbolic trace, the greater the probability value indicating that the coordinate point is the lesion location, which is taken as the pixel value of the localization imaging. Therefore, pixel assignment is carried out on the image (represented by a two-dimensional matrix), different pixel values are represented by different colors, and the deeper the color is, the higher the probability of indicating the existence of the damage is.
Wherein, the probability density function and the cumulative distribution function adopt the following expressions:
accordingly, the lesion localization focused image is:
DIJ(xm,yn)＝1-[F(zIJ)-F(-zIJ)]
wherein z isIJThe shortest distance in mm of the hyperbolic trace determined for the microcell to a pair of piezoelectric sensors I, J as receivers, where I, J represents the ordinal number of the pair of piezoelectric sensors as receivers, such as the first piezoelectric sensor P1As an excitation source, a second piezoelectric sensor P2And a fourth piezoelectric sensor P4As a receiver, then I, J are denoted 2,4, respectively; f (z)IJ) For cumulative distribution function, f (z) is probability density function, DIJ(xm,yn) Pixel value, x, of an element at any point in the image matrixm、ynThe position of the point in the image matrix, in mm, may reflect the coordinates of the corresponding tiny cell, DItotalAnd (3) representing damage positioning focused images obtained by all the piezoelectric sensors, wherein N is the number of the piezoelectric sensors.
Further, as shown in fig. 6, the step S52 further includes: after the damage positioning focusing image is obtained, a threshold value is set for pixel values of all elements in the image matrix, so that the damage position can be displayed more clearly and accurately. The threshold set in the legend is 90%, i.e., more than 90% of the maximum value is displayed, and less than 90% of the maximum value is not displayed. The positioning result is displayed near the actual damage position, and the description of the approximate range of the damage position can also be realized. The monitoring result shows that the method basically detects the damage condition of the structure to be detected without reference signals, and realizes the non-reference damage positioning monitoring.
The above embodiments are merely preferred embodiments of the present invention, which are not intended to limit the scope of the present invention, and various changes may be made in the above embodiments of the present invention. All simple and equivalent changes and modifications made according to the claims and the content of the specification of the present application fall within the scope of the claims of the present patent application. The invention has not been described in detail in order to avoid obscuring the invention.
Claims (6)
1. A no-reference Lamb wave damage monitoring method based on hyperbolic positioning is characterized by comprising the following steps:
step S1: arranging a rhombic piezoelectric excitation/sensing array on a structure to be detected according to the size of a required monitoring area;
step S2: selecting one piezoelectric sensor on one diagonal line of the rhombic piezoelectric excitation/sensing array as an excitation source, exciting an excitation signal of a single Lamb wave mode in a structure to be tested, simultaneously selecting a pair of piezoelectric sensors on a straight line vertical to the diagonal line as receivers, and respectively acquiring a pair of structure response signals corresponding to the current excitation source;
step S3: sequentially taking the rest piezoelectric sensors on the diagonal line as excitation sources, respectively repeating the step S2, and acquiring a plurality of pairs of structure response signals corresponding to different excitation sources;
step S4: acquiring the time difference of a pair of damage scattering signals corresponding to each pair of structural response signals; the respective damage scattered signals in each pair of structural response signals are respectively observed, and the sequence of reaching is qualitatively judged, so that the positive and negative of the time difference are determined, and the distance between the damage position and a pair of piezoelectric sensors serving as a receiver is further judged;
step S5: calculating to obtain the damage position and the approximate range by adopting a hyperbolic positioning method, wherein the method comprises the following steps:
step S51: calculating a damage scattering distance difference according to the time difference obtained in the step S4 and the group velocity c of the excitation signal propagating in the structure to be measured; obtaining hyperbolic traces according to the scattering distance difference of the damage, and calculating by combining all the hyperbolic traces to obtain the damage position;
step S52: performing micro-unit division on a monitoring area of the structure to be detected, establishing a coordinate matrix and a corresponding image matrix, and performing pixel assignment on each element in the image matrix according to a probability density function to obtain a damage positioning focused image; and then, positioning and imaging the approximate range of the damage position according to the coordinates of each piezoelectric sensor of the excitation/sensing array and the damage position obtained in the step S51.
2. The method for monitoring damage to Lamb waves without reference based on hyperbolic positioning as claimed in claim 1, wherein in step S1, the rhombic piezoelectric excitation/sensing array is composed of 4S piezoelectric sensors, S +1 piezoelectric sensors are respectively disposed on each side of the piezoelectric excitation/sensing array and are distributed at equal intervals, and S is a positive integer.
3. The hyperbolic positioning-based benchmarking Lamb wave damage monitoring method of claim 2, wherein in step S1, the piezoelectric excitation/sensing array is composed of 4 piezoelectric sensors, and the piezoelectric excitation/sensing array is square.
4. The hyperbolic positioning-based reference-free Lamb wave damage monitoring method of claim 1, wherein in step S2, the excitation signal of the single Lamb wave mode is applied to the excitation source through an ultrasonic narrowband signal generated by a signal generator after passing through a power amplifier, and is excited by adjusting the frequency; the structural response signals are acquired by acquiring signals received by the receiver through a digital oscilloscope and entering a computer.
5. The hyperbolic positioning-based benchmarking Lamb wave damage monitoring method of claim 1, wherein the step S4 includes:
step S41: normalizing all the structure response signals acquired in the steps S2 and S3 to eliminate errors caused by performance differences of the piezoelectric sensors;
step S42: and respectively carrying out difference subtraction on each pair of normalized structural response signals, according to the theorem of the perpendicular bisector, mutually canceling the direct sensing signals in the structural response signals after the difference subtraction, thereby separating to obtain a pair of damage scattering signals, and determining the time difference of the pair of damage scattering signals according to the time points corresponding to the respective signal peak values of the pair of damage scattering signals.
6. The method for monitoring damage to Lamb waves without reference based on hyperbolic positioning as claimed in claim 1, wherein the time difference Δ t between scattering signals of the pair of damages is obtained in step S4iABComprises the following steps:
ΔtiAB＝tiA-tiB，
wherein, tiAAnd tiBRespectively, a piezoelectric sensor P as an excitation sourceiTo a pair of piezoelectric sensors P as receiversA，PBI is the ordinal number of the piezoelectric sensor as an excitation source, and a and B are the ordinal numbers of the piezoelectric sensor as a receiver, respectively; when i is 1 to 4, if i is 1 or 3, a is 2, B is 4, if i is 2 or 4, a is 1, and B is 3;
and in said step S4, when Δ t is greater thaniABWhen negative, the damage position is close to the A-th piezoelectric sensor PAFar from the Bth piezoelectric sensor PB(ii) a When Δ t is reachediABFor the right time, the damage position is far away from the A-th piezoelectric sensor PANear the Bth piezoelectric sensor PBWhen Δ t isiABWhen the damage position is 0, the damage position is located at the a-th piezoelectric sensor PAWith the B-th piezoelectric sensor PBOr no damage is caused in the structure to be tested.
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111624252A (en) * | 2020-05-25 | 2020-09-04 | 西安交通大学 | Method for improving Lamb wave phased array focusing detection speed |
| CN113219411A (en) * | 2021-05-06 | 2021-08-06 | 哈尔滨工业大学 | Nondestructive equivalent sound source excitation method for simulating ultrahigh-speed impact sound emission of space debris |
| CN113504299A (en) * | 2021-05-28 | 2021-10-15 | 哈尔滨工业大学（威海） | Time difference positioning-based damage identification method for underwater pressure-resistant spherical shell structure |
| CN113804765A (en) * | 2021-10-08 | 2021-12-17 | 金陵科技学院 | Method and system for positioning multiple damage areas of seal head part of pressure vessel |
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| CN113933387A (en) * | 2021-09-08 | 2022-01-14 | 南京邮电大学 | Composite material structure damage monitoring method and system |
| CN113960160A (en) * | 2021-06-29 | 2022-01-21 | 北京交通大学 | Damage detection method and device based on ultrasonic Lamb wave compact array |
| CN114324591A (en) * | 2021-12-31 | 2022-04-12 | 上海理工大学 | Lamb wave packet flight time detection method based on Radon transformation |
| CN114459649A (en) * | 2022-01-19 | 2022-05-10 | 哈尔滨工业大学 | Piezoelectric transducer array-based non-baseline data plane stress field online monitoring method, system, equipment and medium |
| CN114878696A (en) * | 2022-07-06 | 2022-08-09 | 太原理工大学 | Method for identifying layered damage of arc composite laminated plate |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101451977A (en) * | 2008-12-30 | 2009-06-10 | 南京航空航天大学 | Non- reference lamb wave damnification monitoring method based on double-element piezoelectric sensor array and time window function |
| CN101858888A (en) * | 2010-04-16 | 2010-10-13 | 南京航空航天大学 | Structure damage positioning device based on metal core bearing piezoelectric fiber |
| CN106525968A (en) * | 2016-10-19 | 2017-03-22 | 中国人民解放军空军勤务学院 | Damage probability imaging and positioning method based on subareas |
-
2019
- 2019-09-26 CN CN201910918474.7A patent/CN110687208A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101451977A (en) * | 2008-12-30 | 2009-06-10 | 南京航空航天大学 | Non- reference lamb wave damnification monitoring method based on double-element piezoelectric sensor array and time window function |
| CN101858888A (en) * | 2010-04-16 | 2010-10-13 | 南京航空航天大学 | Structure damage positioning device based on metal core bearing piezoelectric fiber |
| CN106525968A (en) * | 2016-10-19 | 2017-03-22 | 中国人民解放军空军勤务学院 | Damage probability imaging and positioning method based on subareas |
Non-Patent Citations (1)
| Title |
|---|
| 魏诺珂: "基于超声兰姆波板状结构损伤定位成像精度研究", 《中国优秀博硕士学位论文全文数据库(硕士) 工程科技Ⅰ辑》 * |
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