CN104777222A - Pipeline defect identification and visualization method based on three-dimensional phase trajectory of Duffing system - Google Patents

Abstract

The invention discloses a pipeline defect identification and visualization method based on the three-dimensional phase trajectory of a Duffing system. The method comprises the following steps: exciting an ultrasonic guided-wave signal through a waveform generator, a power amplifier and a piezoelectric ring, receiving an actual measurement signal through a piezoelectric patch and recording the time travel curve of propagation of ultrasonic guided-waves in a pipeline in virtue of a digital oscilloscope; constructing a Duffing oscillator signal detection system; determining an F value which can be used for identification of the ultrasonic guided-wave signal according to changes of a maximum Lyapunov index with a driving force amplitude F; inputting the middle part of the actual measurement signal into the Duffing oscillator signal detection system with the determined F value, wherein the pipeline is in good condition if a three-dimensional phase trajectory chart has no obvious change, and the pipeline has a defect if the three-dimensional phase trajectory chart is obviously changed; and identifying and positioning the pipeline defect by using a developed visualization system. The method provided by the invention can effectively position defects of different damage degrees in a pipeline and can identify and position defective pipelines through the developed visualization system.

Description

Based on defect of pipeline identification and the method for visualizing of the three-dimensional phase path of Duffing system

Technical field

The present invention relates to a kind of ultrasonic guided wave detection technology, especially a kind of defect of pipeline identification based on the three-dimensional phase path of Duffing system and method for visualizing, belong to technical field of nondestructive testing.

Background technology

In recent years, pipeline is widely used in industry-by-industry, has become the fifth-largest means of transport after railway, highway, air transportation, water transport.But, because pipeline to be inevitably subject to the impact of artificial destruction and the factor such as burn into high temperature, erection (or buried) area surroundings during one's term of military service at it, pipeline accident to be taken place frequently, causes serious consequence.Therefore, health monitoring is carried out to pipeline and become very necessary.Ultrasonic guided wave detection technology is that the long distance line of development in recent years detects innovative techniques.Compared with conventional ultrasonic wave detection technique, supersonic guide-wave excites along waveguiding structure length direction, and its sensing range is " line " but not " point ", and sensing range can reach 50 ~ 100 meters, has become the important method that long distance line detects.

At present, the detection technique for supersonic guide-wave has a lot, mainly can be divided into three parts: one, the Propagation Characteristics of supersonic guide-wave in pipeline configuration; Two, exciting of supersonic guide-wave is studied with receiving trap; Three, signal analysis and defect characteristic extraction etc.Pertinent literature shows to have abundant achievement in research in above-mentioned three.But in the commercial Application of ultrasonic guided wave detection technology, still there are some problems.Especially long distance, the echoed signal under little defect is difficult to be observed.Therefore, domestic and international researcher more and more payes attention to analysis to ultrasonic guided wave signals and research, and has developed many methods effectively.Utilizing chaos system to detect weak signal is a kind of new method that development in recent years is got up, and the method is the initial value sensitivity based on chaos system and the strong immunocompetence to noise.Its principle is: if be input in system using weak signal as the initial value of chaos system, effectively can identify weak signal, and effectively reduce signal-noise ratio threshold, improve detection sensitivity from the response of chaos system.

Conventional chaos detection system mainly contains Lorenz system and Duffing system.Because Duffing system has sinusoidal excitation item, very responsive for periodic signal, therefore, the weak periodic signal detection method based on Duffing oscillator obtains further investigation.The method is carried out by doctor Donald.L.Birx of Dayton university of the U.S. in 1992 at first, but shortage gos deep into theoretical research.Subsequently, researcher utilizes and realizes detecting to the parameter resonance perturbation of Non-Self-Governing Du Fen chaos system, and the correlative study such as system statistics characteristic, weak signal cycle detection, unknown frequency detection, signal amplitude estimation carried out based on chaos detection technology, but major part is round cycle and harmonic signal.Now increasing scholar is also had to utilize Du Fen chaos system to carry out the identification of weak ultrasonic guided wave signals.But mostly concentrate on the identification utilizing two-dimensional phase trajectory diagram to guided wave signals.Two-dimensional phase trajectory diagram is judged to there is a lot of mistaken ideas and deficiency.Easily cause erroneous judgement.And also report is rarely had to the Position Research of defect tracking.In addition, the explanation of ultrasonic guided wave detecting data needs by doing some training very often, particularly carrying out the technician that the piping system of complex geometric shapes has wide experience, and the technology that is unsuitable for significantly is promoted.

Summary of the invention

The object of the invention is the defect in order to solve conventional ultrasonic wave detection technique, a kind of defect of pipeline identification based on the three-dimensional phase path of Duffing system and method for visualizing are provided, the method not only can carry out effective location to the defect of ducted Injured level, thus improve supersonic guide-wave identification little defect sensitivity, effectively extend sensing range, and by exploitation MATLAB visualization system, make layman also can realize succinct, directly perceived, vivid identification and location defect pipeline, there is certain practicality and dissemination.

Object of the present invention can reach by taking following technical scheme:

Based on defect of pipeline identification and the method for visualizing of the three-dimensional phase path of Duffing system, comprise the following steps:

1) waveform generator generates the signal through the modulation of Hanning window, is amplified, remake the piezoelectric ring for pipeline one side end face by power amplifier, excites the ultrasonic guided wave signals through the modulation of Hanning window, makes supersonic guide-wave travel through all positions of pipeline;

2) receive measured signal by being arranged on piezoelectric patches on pipeline, and by the time-history curves that digital oscilloscope record supersonic guide-wave is propagated in the duct, by digital oscilloscope by the information transmission of record to computing machine;

3) set the incident wave signal of the intact pipeline collected in advance, edge echo signal and the ultrasonic guided wave signals of numerical simulation, pure noise signal as detection signal, according to centre frequency, the sample frequency of this detection signal, and duffing equation characteristic, structure Duffing vibrator signal detection system;

4) ultrasonic guided wave signals of the incident wave signal of the intact pipeline collected in advance, edge echo signal and numerical simulation, pure noise signal are input to Duffing vibrator signal detection system respectively, during by comparing no signal input, incident wave signal, edge echo signal, ultrasonic guided wave signals and pure noise signal, maximum Lyapunov exponent, with the change of driving force amplitude F, determines the F value that can be used for identifying ultrasonic guided wave signals;

5) input of the center section signal of the measured signal received is determined the Duffing vibrator signal detection system of F value, analyze this center section signal to the impact of three-dimensional phase path figure, if three-dimensional phase path figure is without significant change, when namely system is still in large period state, then pipeline is intact; If three-dimensional phase path figure generation significant change, when namely system becomes chaos state from large period state, then pipeline defectiveness, enters step 6);

6) according to the MATLAB visualization system of exploitation, completed the visual identification of defect of pipeline by the phase path figure of Duffing vibrator signal detection system, three-dimensional phase path figure and Lyapunov index, and utilize Lyapunov index to carry out the location of defect of pipeline.

As a kind of embodiment, step 1) the described ultrasonic guided wave signals expression formula through the modulation of Hanning window is as follows:

$s\left(t\right)=\left[\frac{1}{2}(1-\cos \frac{w_{c}t}{n}\right)].\sin \left(w_{c}t\right)---\left(1\right)$

Wherein, n is the single audio frequency number selected, w _c=2 π f _c, f _cfor the centre frequency of signal, be 70KHz.

As a kind of embodiment, step 3) described structure Duffing vibrator signal detection system, specific as follows:

A) choose duffing equation, it comprises the complex state of vibration, fork, chaos, and its expression formula is:

$\stackrel{\·\·}{x}+k\stackrel{\·}{x}-x^3+x^5=F\mathrm{}\cos \mathrm{}\mathrm{\ωt}---\left(2\right)$

Wherein, k is damping ratio, (-x ³+ x ⁵) be nonlinear resilience item; Fcos ω t is driving force item, and F is driving force amplitude, and ω is driving force angular frequency;

B) set the incident wave signal of the intact pipeline collected in advance, edge echo signal and the ultrasonic guided wave signals of numerical simulation, pure noise signal as detection signal and its centre frequency is 70KHz, sample frequency is 50M time/second, then sets the ω ≈ 0.439823rad/ μ s of duffing equation, integration step h=0.02 μ s, damping ratio k=0.5, improves as follows to formula (2):

$\stackrel{\·\·}{x}+k\stackrel{\·}{x}-x^3+x^5=F\mathrm{}\cos \mathrm{}\mathrm{\ωt}+\stackrel{\‾}{s}\left(t\right)---\left(3\right)$

C) choose displacement x and speed v, formula (3) rewritten as follows:

$\left\{\begin{array}{c}\stackrel{\·}{x}=v\\ \stackrel{\·}{v}=-\mathrm{cv}+x^3-x^5+F\mathrm{}\cos \mathrm{}\mathrm{\ωz}\\ \stackrel{\·}{z}=1\end{array}\right.---\left(4\right)$

Above-mentioned formula (3) is Duffing vibrator signal detection system, and formula (4) is three-dimensional autonomous system.

As a kind of embodiment, step 5) the Lyapunov Index Definition of described duffing equation is as follows:

$\left\{\begin{array}{c}{\mathrm{\λ}}_1=\underset{N\→\∞}{\lim }\frac{1}{\mathrm{NT}}\underset{k=1}{\overset{N}{\mathrm{\Σ}}}\ln \left|\right|V_1^k\left|\right|\\ {\mathrm{\λ}}_2=\underset{N\→\∞}{\lim }\frac{1}{\mathrm{NT}}\underset{k=1}{\overset{N}{\mathrm{\Σ}}}\ln \left|\right|V_2^k\left|\right|\\ {\mathrm{\λ}}_3=\underset{N\→\∞}{\lim }\frac{1}{\mathrm{NT}}\underset{k=1}{\overset{N}{\mathrm{\Σ}}}\ln \left|\right|V_3^k\left|\right|\end{array}\right.---\left(5\right)$

Corresponding 3 the Lyapunov indexes of three-dimensional duffing equation, sort by its size, are called Lyapunov exponential spectrum; If maximum Lyapunov exponent λ ₁be greater than 0, then system is in chaos state, if maximum Lyapunov exponent λ ₁be less than 0, then system is in large period or quasi-periodic motion state.

As a kind of embodiment, step 6) the described Lyapunov of utilization index carries out the location of defect of pipeline:

A) define Moving Window function, select window length 2 δ=50 μ s, window translational speed τ=5 μ s, by Moving Window function scanning measured signal, calculate the maximum Lyapunov exponent of each segment signal;

B) be greater than the center section signal of 0 in maximum Lyapunov exponent, the envelope peak value of selection maximum Lyapunov exponent to the moment, then carries out the location of defect of pipeline as ripple.

As a kind of embodiment, described Moving Window function is defined as follows:

S ^*＝g(t-nτ)S (6)

$g(t-\mathrm{n\τ})=1,t\∈(\mathrm{n\τ}-\mathrm{\δ},\mathrm{n\τ}+\mathrm{\δ}),n=\frac{\mathrm{\δ}}{\mathrm{\τ}},\frac{\mathrm{\δ}+\mathrm{\τ}}{\mathrm{\τ}},\frac{\mathrm{\δ}+2\mathrm{\τ}}{\mathrm{\τ}}...,\frac{N-\mathrm{\δ}}{\mathrm{\τ}}---\left(7\right)$

Wherein, S represents the full time-domain signal recorded, S ^*represent intercept signal, N represents signal length, and 2 δ represent window length, and τ represents window translational speed.

As a kind of embodiment, the location of described defect of pipeline adopts following formula to calculate:

$d_x=\frac{t_2-t_1}{t_3-t_1}d---\left(8\right)$

Wherein, d _xrepresent that in pipe, defect is from the distance exciting end, d represents duct length, t ₁, t ₂and t ₃represent the moment that incident wave, flaw echo and edge echo receive respectively.

As a kind of embodiment, the location of described defect of pipeline adopts following formula to calculate:

2d _x＝ct (9)

Wherein, c is velocity of propagation conventional in steel pipe, and namely c=5300m/s, t represent the moment of the ripple received, d _xrepresent that t pipeline location is from the distance exciting end.

The present invention has following beneficial effect relative to prior art:

1, the present invention is the pipe ultrasonic guided wave defect identification method based on the three-dimensional phase path figure of Duffing system, according to the center section signal of the measured signal received on the impact of three-dimensional phase path figure, pipeline whether defectiveness can be detected, little flaw detection sensitivity can be improved, there is innovative significance, have a wide range of applications.

2, the present invention is by the MATLAB visualization system of exploitation, makes layman also can realize succinct, directly perceived, vivid identification and location defect pipeline, has certain practicality and dissemination.

Accompanying drawing explanation

The principle of instrument block diagram that Fig. 1 adopts for the embodiment of the present invention 1.

Fig. 2 is defect of pipeline identification and the method for visualizing process flow diagram of the embodiment of the present invention 1.

Fig. 3 is λ before and after the intact pipeline incident wave of the embodiment of the present invention 2, edge echo signal and the ultrasonic guided wave signals of numerical simulation, pure noise signal input Duffing vibrator signal detection system ₁variation diagram.

Duffing vibrator signal detection system timeamplitude map when Fig. 4 a is driving force F=0.516; The three-dimensional phase path figure of Duffing vibrator signal detection system when Fig. 4 b is driving force F=0.516.

Fig. 5 a is the timeamplitude map of operating mode one incident wave signal; Fig. 5 b is the three-dimensional phase path figure adding Duffing vibrator signal detection system after operating mode one incident wave signal.

Fig. 6 a is the timeamplitude map of operating mode one end face echoed signal; Fig. 6 b is the three-dimensional phase path figure adding Duffing vibrator signal detection system after operating mode one end face echoed signal.

Fig. 7 a is the timeamplitude map of operating mode one center section signal; Fig. 7 b is the three-dimensional phase path figure adding Duffing vibrator signal detection system after operating mode one center section signal.

Fig. 8 a is the timeamplitude map of the pure noise signal of operating mode two; Fig. 8 b is the three-dimensional phase path figure adding Duffing vibrator signal detection system after the pure noise signal of operating mode two.

Fig. 9 a is the timeamplitude map of operating mode two fault location signal; Fig. 9 b is the three-dimensional phase path figure adding Duffing vibrator signal detection system after operating mode two fault location signal.

Figure 10 a is the timeamplitude map of the pure noise signal of operating mode three; Figure 10 b is the three-dimensional phase path figure adding Duffing vibrator signal detection system after the pure noise signal of operating mode three.

Figure 11 a is the timeamplitude map of operating mode three fault location signal; Figure 11 b is the three-dimensional phase path figure adding Duffing vibrator signal detection system after operating mode three fault location signal.

Figure 12 a is the timeamplitude map of the pure noise signal of operating mode four; Figure 12 b is the three-dimensional phase path figure adding Duffing vibrator signal detection system after the pure noise signal of operating mode four.

Figure 13 a is the timeamplitude map of operating mode three fault location signal; Figure 13 b is the three-dimensional phase path figure adding Duffing vibrator signal detection system after operating mode three fault location signal.

Figure 14 is operating mode three multi objective non-destructive tests result figure in MATLAB visualization system.

Figure 15 is operating mode one damage reason location result figure in MATLAB visualization system.

Figure 16 is operating mode two damage reason location result figure in MATLAB visualization system.

Embodiment

Embodiment 1:

As shown in Figure 1, the instrument that the present embodiment adopts comprises waveform generator, power amplifier, digital oscilloscope, piezoelectric ring and piezoelectric patches, described piezoelectric ring is arranged on pipeline one side end face, described piezoelectric patches is arranged on pipeline, described waveform generator, power amplifier are connected successively with piezoelectric ring, described waveform generator is connected with digital oscilloscope respectively with piezoelectric patches, and described digital oscilloscope is connected with computing machine.

As described in Figure 2, the defect of pipeline identification of the present embodiment and method for visualizing comprise the following steps:

1) waveform generator generates the signal through the modulation of Hanning window, is amplified, remake the piezoelectric ring for pipeline one side end face by power amplifier, excites the ultrasonic guided wave signals through the modulation of Hanning window, makes supersonic guide-wave travel through all positions of pipeline;

2) receive measured signal by piezoelectric patches on pipeline, and by the time-history curves that digital oscilloscope record supersonic guide-wave is propagated in the duct, by digital oscilloscope by the information transmission of record to computing machine;

3) set the incident wave signal of the intact pipeline collected in advance, edge echo signal and the ultrasonic guided wave signals of numerical simulation, pure noise signal as detection signal, according to centre frequency, the sample frequency of this detection signal, and duffing equation characteristic, structure Duffing vibrator signal detection system;

4) ultrasonic guided wave signals of the incident wave signal of the intact pipeline collected in advance, edge echo signal and numerical simulation, pure noise signal are input to Duffing vibrator signal detection system respectively, during by comparing no signal input, incident wave signal, edge echo signal, ultrasonic guided wave signals and pure noise signal, maximum Lyapunov exponent, with the change of driving force amplitude F, determines the F value that can be used for identifying ultrasonic guided wave signals;

5) input of the center section signal of the measured signal received is determined the Duffing vibrator signal detection system of F value, analyze this center section signal to the impact of three-dimensional phase path figure, if three-dimensional phase path figure is without significant change, when namely system is still in large period state, then pipeline is intact; If three-dimensional phase path figure generation significant change, when namely system becomes chaos state from large period state, then pipeline defectiveness, enters step 6);

6) according to the MATLAB visualization system of exploitation, completed the visual identification of defect of pipeline by the phase path figure of Duffing vibrator signal detection system, three-dimensional phase path figure and Lyapunov index, and utilize Lyapunov index to carry out the location of defect of pipeline.

Embodiment 2:

The present embodiment is for specific experiment, and carry out defect recognition and location in laboratory to pipeline, specific implementation process is as follows:

1) steel pipe of selection for pipeline 3mm × 50.75mm × 2.32mm, described piezoelectric ring and piezoelectric patches all adopt PZT5 material, wherein the size of piezoelectric ring is according to pipeline section manufacture, piezoelectric patches is of a size of 15.4mm × 3.2.mm × 0.9mm, use four install pipelines, four kinds of operating modes respectively, wherein operating mode one is flawless intact pipeline, and operating mode two, three and four is all utilize saw bow to excite the 1.5m place of end to arrange artificial defect at distance piezoelectric patches place, and design parameter is as shown in table 1 below.

Table 1 four kinds of operating mode defects arrange table

2) waveform generator generates the signal through the modulation of Hanning window, amplified by power amplifier, remake the piezoelectric ring of pipeline one side end face for four kinds of operating modes, excite the ultrasonic guided wave signals through the modulation of Hanning window, make supersonic guide-wave travel through all positions of pipeline;

Expression formula through the ultrasonic guided wave signals of Hanning window modulation is as follows:

$s\left(t\right)=\left[\frac{1}{2}(1-\cos \frac{w_{c}t}{n}\right)].\sin \left(w_{c}t\right)---\left(1\right)$

Wherein, n is the single audio frequency number selected, w _c=2 π f _c, f _cfor the centre frequency of signal, be 70KHz.

3) received the measured signal of four kinds of operating modes by the piezoelectric patches on pipeline, and by the time-history curves that digital oscilloscope record supersonic guide-wave is propagated in the duct, by digital oscilloscope by the information transmission of record to computing machine;

4) Duffing vibrator signal detection system is constructed

A) choose duffing equation, duffing equation is the common model in Detection of Weak Signals, and the nonlinear system described by it shows multiple nonlinear characteristic, comprises the complex state of vibration, fork, chaos, and its expression formula is:

$\stackrel{\·\·}{x}+k\stackrel{\·}{x}-x^3+x^5=F\mathrm{}\cos \mathrm{}\mathrm{\ωt}---\left(2\right)$

Wherein, k is damping ratio, (-x ³+ x ⁵) be nonlinear resilience item; Fcos ω t is driving force item, and F is driving force amplitude, and ω is driving force angular frequency;

The pure noise signal of the incident wave signal of the intact pipeline b) setting laboratory to collect, edge echo signal and numerical simulation is as detection signal and its centre frequency is 70KHz, sample frequency is 50M time/second, then sets the ω ≈ 0.439823rad/ μ s of duffing equation, integration step h=0.02 μ s, damping ratio k=0.5, improves as follows to formula (2):

$\stackrel{\·\·}{x}+k\stackrel{\·}{x}-x^3+x^5=F\mathrm{}\cos \mathrm{}\mathrm{\ωt}+\stackrel{\‾}{s}\left(t\right)---\left(3\right)$

Utilize simple triangular transformation, formula (3) still can be classified as the form of formula (2) by abbreviation.Therefore, can think and be equivalent to input synperiodic sine (or cosine) signal amplitude and the phase place of the formula that changes (2) driving force item, cause the change of system output characteristic, thus realize input signal analysis.

C) choose displacement x and speed v, formula (3) rewritten as follows:

$\left\{\begin{array}{c}\stackrel{\·}{x}=v\\ \stackrel{\·}{v}=-\mathrm{cv}+x^3-x^5+F\mathrm{}\cos \mathrm{}\mathrm{\ωz}\\ \stackrel{\·}{z}=1\end{array}\right.---\left(4\right)$

Above-mentioned formula (3) is Duffing vibrator signal detection system, and formula (4) is three-dimensional autonomous system.

5) definition of Lyapunov index

The essential characteristic of chaos system is that motion is very responsive to initial condition, the track exponentially mode of passing in time that two close initial values produce is separated, Lyapunov index is the quantitative target describing this phenomenon, the average index rate that As time goes on system that characterizes restrains between adjacent orbit or disperse in phase space.

The Lyapunov index of duffing equation, is defined as follows:

$\left\{\begin{array}{c}{\mathrm{\λ}}_1=\underset{N\→\∞}{\lim }\frac{1}{\mathrm{NT}}\underset{k=1}{\overset{N}{\mathrm{\Σ}}}\ln \left|\right|V_1^k\left|\right|\\ {\mathrm{\λ}}_2=\underset{N\→\∞}{\lim }\frac{1}{\mathrm{NT}}\underset{k=1}{\overset{N}{\mathrm{\Σ}}}\ln \left|\right|V_2^k\left|\right|\\ {\mathrm{\λ}}_3=\underset{N\→\∞}{\lim }\frac{1}{\mathrm{NT}}\underset{k=1}{\overset{N}{\mathrm{\Σ}}}\ln \left|\right|V_3^k\left|\right|\end{array}\right.---\left(5\right)$

Corresponding 3 the Lyapunov indexes of three-dimensional duffing equation, sort by its size, are called Lyapunov exponential spectrum; If maximum Lyapunov exponent λ ₁be greater than 0, then system is in chaos state, if maximum Lyapunov exponent λ ₁be less than 0, then system is in large period or quasi-periodic motion state.

6) the incident wave signal of the operating mode one (i.e. intact pipeline) received, edge echo signal and the ultrasonic guided wave signals of numerical simulation, pure noise signal are input to Duffing vibrator signal detection system respectively, i.e. formula (3), wherein pure noise signal σ e (t) represents, wherein σ is a random function analogue noise, e (t) is noise level, be 0.05 herein, and draw and add λ before and after these signals ₁with the effect diagram of driving force F change, as shown in Figure 3; In F ∈ (0.5,0.52) scope, no signal inputs and inputs pure noise signal, λ ₁all be less than 0, expression system is periodic motion or quasi-periodic motion, and the ultrasonic guided wave signals of the incident wave that input receives, edge echo signal, numerical simulation, λ ₁all become and be greater than 0, represent that now system is chaos state, and select λ ₁the driving force amplitude F=0.516 of change degree maximum carries out the identification of ultrasonic guided wave signals, now the time-history curves (time history curve) of Duffing vibrator signal detection system and three-dimensional phase path figure as shown in Figs. 4a and 4b respectively;

7) based on the Duffing vibrator signal detection system of above-mentioned driving force F=0.516, the phase path of this Duffing vibrator signal detection system is utilized to carry out the defect recognition of pipeline

A) respectively the incident wave signal of the operating mode one (i.e. intact pipeline) received, edge echo signal are inputted Duffing vibrator signal detection system, wherein the time-history curves of incident wave signal as shown in Figure 5 a, and the three-dimensional phase path figure after input Duffing vibrator signal detection system as shown in Figure 5 b, the time-history curves of edge echo signal as shown in Figure 6 a, three-dimensional phase path figure after input Duffing vibrator signal detection system as shown in Figure 6 b, observe the change of three-dimensional phase path figure, as can be seen from Fig. 5 b, 6b and Fig. 4 b relatively in, under the impact of ultrasonic guided wave signals, the three-dimensional phase path figure of system is from large period state, there occurs significant change, become chaos state, utilize this change just, carry out the identification of ultrasonic guided wave signals, as a comparison, the center section signal (signal namely between incident wave signal and edge echo signal) of operating mode one is inputted Duffing vibrator signal detection system, the time-history curves of center section signal as shown in Figure 7a, three-dimensional phase path figure after input Duffing vibrator signal detection system as shown in Figure 7b, observe the change of three-dimensional phase path figure, as can be seen from Fig. 7 b and Fig. 4 b relatively in, owing to there is no flaw echo, signal is herein equivalent to pure noise signal, input Duffing vibrator signal detection system, obvious change can not be there is in its three-dimensional phase path figure, or significantly large period state.Further illustrate the feasibility of three-dimensional phase recognition.

B) in order to verify the validity of above-mentioned three-dimensional phase recognition further, respectively by the center section signal of operating mode two, three, four input Duffing vibrator signal detection system, operating mode two due to defect smaller, direct observation time-history curves, be difficult to see obvious flaw echoes, by center section signal subsection input Duffing vibrator signal detection system, for wherein two sections, the time-history curves of first paragraph as shown in Figure 8 a, three-dimensional phase path figure after input Duffing vibrator signal detection system as shown in Figure 8 b, can find out with the comparing of Fig. 4 b, the three-dimensional phase path figure of Duffing vibrator signal detection system is without significant change, system is still in large period state, illustrate that this part is pure noise signal, also zero defect echoed signal is described, and then zero defect, the time-history curves of second segment as illustrated in fig. 9, three-dimensional phase path figure after input Duffing vibrator signal detection system as shown in figure 9b, can find out with the comparing of Fig. 4 b, the three-dimensional phase path figure generation significant change of Duffing vibrator signal detection system, large period state when inputting from no signal has become chaos state, thus illustrate containing weak guided wave signals, further illustrate containing defectiveness.By the center section signal of operating mode three, four input Duffing vibrator signal detection system, wherein the time-history curves of the pure noise signal of operating mode three as shown in Figure 10 a, as shown in fig. lob, the time-history curves at operating mode three flaw indication place is as Figure 11 for three-dimensional phase path figure after input Duffing vibrator signal detection system _ashown in, the three-dimensional phase path figure after input Duffing vibrator signal detection system is as shown in figure lib; The pure noise signal time-history curves of operating mode four as figure 12 a shows, three-dimensional phase path figure after input Duffing vibrator signal detection system as shown in Figure 12b, as depicted in fig. 13 a, the three-dimensional phase path figure after input Duffing vibrator signal detection system as illustrated in fig. 13b for the time-history curves at operating mode four flaw indication place; Observe the change of three-dimensional phase path figure, same conclusion can be obtained.

8) use of conveniently layman, develop MATLAB visualization system to operate, utilize several common counters of Duffing vibrator signal detection system as indexs such as phase path figure, three-dimensional phase path figure and Lyapunov indexes, complete the visual identification of defect of pipeline, detailed process is as follows:

Utilize the different indexs of Duffing vibrator signal detection system respectively, carry out non-destructive tests: for operating mode three, select driving force amplitude F=0.516, now corresponding two-dimensional phase trajectory diagram, three-dimensional phase path figure is all in the maximum Lyapunov exponent λ of large period state and correspondence ₁be less than 0, as shown in figure 14, it can also be seen that from figure, when guided wave signals amplitude com parison is large, the change of three all clearly, but when guided wave signals is fainter, as the feeble signal represented by input intercept signal, two-dimensional phase trajectory diagram is easily judged by accident, Lyapunov index is also close to 0, and three-dimensional phase path figure still has significant change, this also illustrates that the three-dimensional phase path utilizing Duffing vibrator signal detection system identifies to have dominance;

9) at MATLAB visualization system, Lyapunov index is utilized to carry out the location of defect of pipeline, specific as follows:

Definition Moving Window function:

S ^*＝g(t-nτ)S (6)

$g(t-\mathrm{n\τ})=1,t\∈(\mathrm{n\τ}-\mathrm{\δ},\mathrm{n\τ}+\mathrm{\δ}),n=\frac{\mathrm{\δ}}{\mathrm{\τ}},\frac{\mathrm{\δ}+\mathrm{\τ}}{\mathrm{\τ}},\frac{\mathrm{\δ}+2\mathrm{\τ}}{\mathrm{\τ}}...,\frac{N-\mathrm{\δ}}{\mathrm{\τ}}---\left(7\right)$

Wherein, S represents the full time-domain signal recorded, S ^*represent intercept signal, N represents signal length, and 2 δ represent window length, and τ represents window translational speed.Utilize Moving Window function to scan operating mode one, signal corresponding to operating mode two, and select window length 2 δ=50 μ s, window translational speed τ=5 μ s respectively, calculate the λ of each segment signal ₁, provide several multi-form result, respectively as shown in Figure 15 and Figure 16, as can be seen from Figure 15, operating mode one is intact pipeline, owing to there is no defect, only at incident wave and edge echo place, and λ ₁obviously be greater than 0, form a similar envelope shape with ripple bag; As can see from Figure 16, operating mode two due to defect smaller, time-history curves cannot differentiate place's flaw echo, and the λ of center section signal by calculating ₁obviously be greater than 0, the existence of defect can be determined.As long as owing to there is weak signal, even if signal is imperfect also can make λ ₁obviously be greater than 0, the λ therefore calculated ₁the time zone being obviously greater than 0 is a scope.Select λ ₁envelope peak value as ripple to the moment, provide two kinds of damage positioning methods, wherein a kind of localization method adopts following formula to calculate:

$d_x=\frac{t_2-t_1}{t_3-t_1}d---\left(8\right)$

Wherein, d _xrepresent that in pipe, defect is from the distance exciting end, d represents duct length, t ₁, t ₂and t ₃represent the moment that incident wave, flaw echo and edge echo receive respectively.

Another kind of localization method adopts following formula to calculate:

2d _x＝ct (9)

Wherein, c is velocity of propagation conventional in steel pipe, and namely c=5300m/s, t represent the moment of the ripple received, d _xrepresent that t pipeline location is from the distance exciting end.

Above-mentioned two kinds of localization methods, can also pass through following formula error of calculation number percent:

$r=\left|\frac{{2d}_x-d}{2d}\right|\×100\%---\left(10\right)$

Wherein, r represents relative error.

In sum, the inventive method not only can carry out effective location to the defect of ducted Injured level, thus improve supersonic guide-wave identification little defect sensitivity, effectively extend sensing range, and by exploitation MATLAB visualization system, make layman also can realize succinct, directly perceived, vivid identification and location defect pipeline, there is certain practicality and dissemination.

The above; be only patent preferred embodiment of the present invention; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in scope disclosed in this invention; be equal to according to technical scheme of the present invention and inventive concept thereof and replace or change, all belonged to protection scope of the present invention.

Claims (8)

1., based on defect of pipeline identification and the method for visualizing of the three-dimensional phase path of Duffing system, it is characterized in that comprising the following steps:

1) waveform generator generates the signal through the modulation of Hanning window, is amplified, remake the piezoelectric ring for pipeline one side end face by power amplifier, excites the ultrasonic guided wave signals through the modulation of Hanning window, makes supersonic guide-wave travel through all positions of pipeline;

2) receive measured signal by being arranged on piezoelectric patches on pipeline, and by the time-history curves that digital oscilloscope record supersonic guide-wave is propagated in the duct, by digital oscilloscope by the information transmission of record to computing machine;

3) set the incident wave signal of the intact pipeline collected in advance, edge echo signal and the ultrasonic guided wave signals of numerical simulation, pure noise signal as detection signal, according to centre frequency, the sample frequency of this detection signal, and duffing equation characteristic, structure Duffing vibrator signal detection system;

4) ultrasonic guided wave signals of the incident wave signal of the intact pipeline collected in advance, edge echo signal and numerical simulation, pure noise signal are input to Duffing vibrator signal detection system respectively, during by comparing no signal input, incident wave signal, edge echo signal, ultrasonic guided wave signals and pure noise signal, maximum Lyapunov exponent, with the change of driving force amplitude F, determines the F value that can be used for identifying ultrasonic guided wave signals;

5) input of the center section signal of the measured signal received is determined the Duffing vibrator signal detection system of F value, analyze this center section signal to the impact of three-dimensional phase path figure, if three-dimensional phase path figure is without significant change, when namely system is still in large period state, then pipeline is intact; If three-dimensional phase path figure generation significant change, when namely system becomes chaos state from large period state, then pipeline defectiveness, enters step 6);

6) according to the MATLAB visualization system of exploitation, completed the visual identification of defect of pipeline by the phase path figure of Duffing vibrator signal detection system, three-dimensional phase path figure and Lyapunov index, and utilize Lyapunov index to carry out the location of defect of pipeline.

2. the defect of pipeline identification based on the three-dimensional phase path of Duffing system according to claim 1 and method for visualizing, is characterized in that: step 1) the described ultrasonic guided wave signals expression formula through the modulation of Hanning window is as follows:

$s\left(t\right)=\left[\frac{1}{2}(1-\cos \frac{w_{c}t}{n})\right]\·\sin \left(w_{c}t\right)---\left(1\right)$

Wherein, n is the single audio frequency number selected, w _c=2 π f _c, f _cfor the centre frequency of signal, be 70KHz.

3. the defect of pipeline identification based on the three-dimensional phase path of Duffing system according to claim 1 and method for visualizing, is characterized in that: step 3) described structure Duffing vibrator signal detection system, specific as follows:

A) choose duffing equation, it comprises the complex state of vibration, fork, chaos, and its expression formula is:

$\stackrel{\·\·}{x}+k\stackrel{\·}{x}-x^3+x^5=F\cos \mathrm{\ωt}---\left(2\right)$

Wherein, k is damping ratio, (-x ³+ x ⁵) be nonlinear resilience item; Fcos ω t is driving force item, and F is driving force amplitude, and ω is driving force angular frequency;

B) set the incident wave signal of the intact pipeline collected in advance, edge echo signal and the ultrasonic guided wave signals of numerical simulation, pure noise signal as detection signal , and its centre frequency is 70KHz, sample frequency is 50M time/second, then sets the ω ≈ 0.439823rad/ μ s of duffing equation, integration step h=0.02 μ s, damping ratio k=0.5, improves as follows to formula (2):

$\stackrel{\·\·}{x}+k\stackrel{\·}{x}-x^3+x^5=F\cos \mathrm{\ωt}+\stackrel{\‾}{s}\left(t\right)---\left(3\right)$

C) choose displacement x and speed v, formula (3) rewritten as follows:

$\left\{\begin{array}{c}\stackrel{\·}{x}=v\\ \stackrel{\·}{v}=-\mathrm{cv}+x^3-x^5+F\cos \mathrm{\ωz}\\ \stackrel{\·}{z}=1\end{array}\right.---\left(4\right)$

Above-mentioned formula (3) is Duffing vibrator signal detection system, and formula (4) is three-dimensional autonomous system.

4. the defect of pipeline identification based on the three-dimensional phase path of Duffing system according to claim 3 and method for visualizing, is characterized in that: step 5) the Lyapunov Index Definition of described duffing equation is as follows:

$\left\{\begin{array}{c}{\mathrm{\λ}}_1=\underset{N\→\∞}{\lim }\frac{1}{\mathrm{NT}}\underset{k=1}{\overset{N}{\mathrm{\Σ}}}\ln \left|\right|V_1^k\left|\right|\\ {\mathrm{\λ}}_2=\underset{N\→\∞}{\lim }\frac{1}{\mathrm{NT}}\underset{k=1}{\overset{N}{\mathrm{\Σ}}}\ln \left|\right|V_2^k\left|\right|\\ {\mathrm{\λ}}_3=\underset{N\→\∞}{\lim }\frac{1}{\mathrm{NT}}\underset{k=1}{\overset{N}{\mathrm{\Σ}}}\ln \left|\right|V_3^k\left|\right|\end{array}\right.---\left(5\right)$

Corresponding 3 the Lyapunov indexes of three-dimensional duffing equation, sort by its size, are called Lyapunov exponential spectrum; If maximum Lyapunov exponent λ ₁be greater than 0, then system is in chaos state, if maximum Lyapunov exponent λ ₁be less than 0, then system is in large period or quasi-periodic motion state.

5. the defect of pipeline identification based on the three-dimensional phase path of Duffing system according to claim 1 and method for visualizing, is characterized in that: step 6) the described Lyapunov of utilization index carries out the location of defect of pipeline:

A) define Moving Window function, select window length 2 δ=50 μ s, window translational speed τ=5 μ s, by Moving Window function scanning measured signal, calculate the maximum Lyapunov exponent of each segment signal;

B) be greater than the center section signal of 0 in maximum Lyapunov exponent, the envelope peak value of selection maximum Lyapunov exponent to the moment, then carries out the location of defect of pipeline as ripple.

6. the defect of pipeline identification based on the three-dimensional phase path of Duffing system according to claim 5 and method for visualizing, is characterized in that: described Moving Window function is defined as follows:

S ^*＝g(t-nτ)S (6)

$g(t-\mathrm{n\τ})=1,t\∈(\mathrm{n\τ}-\mathrm{\δ},\mathrm{n\τ}+\mathrm{\δ}),n=\frac{\mathrm{\δ}}{\mathrm{\τ}},\frac{\mathrm{\δ}+\mathrm{\τ}}{\mathrm{\τ}},\frac{\mathrm{\δ}+2\mathrm{\τ}}{\mathrm{\τ}}...,\frac{N-\mathrm{\δ}}{\mathrm{\τ}}---\left(7\right)$

Wherein, S represents the full time-domain signal recorded, S ^*represent intercept signal, N represents signal length, and 20,000 represent window length, and τ represents window translational speed.

7. the defect of pipeline identification based on the three-dimensional phase path of Duffing system according to claim 5 and method for visualizing, is characterized in that: the location of described defect of pipeline adopts following formula to calculate:

$d_x=\frac{t_2-t_1}{t_3-t_1}d---\left(8\right)$

Wherein, d _xrepresent that in pipe, defect is from the distance exciting end, d represents duct length, t ₁, t ₂and t ₃represent the moment that incident wave, flaw echo and edge echo receive respectively.

8. the defect of pipeline identification based on the three-dimensional phase path of Duffing system according to claim 5 and method for visualizing, is characterized in that: the location of described defect of pipeline adopts following formula to calculate:

2d _x＝ct (9)

Wherein, c is velocity of propagation conventional in steel pipe, and namely c=5300m/s, t represent the moment of the ripple received, d _xrepresent that t pipeline location is from the distance exciting end.