阅读说明：本技术 高效激励螺旋周向兰姆波的磁致伸缩贴片式传感器及其工作方法 (Magnetostrictive patch type sensor for efficiently exciting spiral circumferential lamb waves and working method thereof ) 是由 方舟 黄宴委 于 2021-09-14 设计创作，主要内容包括：本发明提出一种高效激励螺旋周向兰姆波的磁致伸缩贴片式传感器及其工作方法,实现利用螺旋传播的周向兰姆波,对管道中的轴向缺陷进行轴向定位,同时能够评估管道中缺陷的轴向范围。为实现管道中轴向缺陷的定位以及缺陷周向范围的评估,本发明利用对轴向缺陷敏感的周向兰姆波沿着管道的轴向螺旋传播,根据信号中的缺陷反射信号来判断缺陷轴向位置,以及总结带有缺陷反射的信号数量来评估缺陷的轴向长度,采取理论模型与实验对比的方式来实现。另外,该方法支持自激励自接收的测量模式,能够适应工程测量中只有一端管道能够装载传感器的情况。(The invention provides a magnetostrictive patch type sensor for efficiently exciting spiral circumferential lamb waves and a working method thereof, which are used for axially positioning axial defects in a pipeline by using the spirally transmitted circumferential lamb waves and can evaluate the axial range of the defects in the pipeline. In order to realize the positioning of the axial defects in the pipeline and the evaluation of the circumferential range of the defects, the invention utilizes circumferential lamb waves sensitive to the axial defects to be spirally transmitted along the axial direction of the pipeline, judges the axial positions of the defects according to defect reflection signals in the signals, summarizes the number of the signals with the defect reflection to evaluate the axial length of the defects, and adopts a mode of comparing a theoretical model with an experiment. In addition, the method supports a self-excitation and self-receiving measurement mode, and can adapt to the condition that only one end of a pipeline can be loaded with a sensor in engineering measurement.)

1. A magnetostrictive patch type sensor for efficiently exciting a spiral circumferential lamb wave is characterized by comprising: a flexible printed coil and magnetostrictive material for exciting a helically propagating circumferential lamb wave; the magnetostrictive material is used for being adhered to a pipeline, and the flexible printing coil is adhered to the magnetostrictive material.

2. The magnetostrictive patch sensor for highly efficient excitation of helical circumferential lamb waves according to claim 1, wherein: the flexible printed coil is divided into two layers, and a circuit of a first layer of the coil comprises a plurality of groups of horse race field coils formed by connecting two sections in series; the circuit of the second layer is a lead wire for connecting two adjacent groups of horse race field coils; the terminal of each section of the horse race field coil is provided with a through hole for connecting the first layer circuit and the second layer circuit.

3. The magnetostrictive patch sensor for highly efficient excitation of helical circumferential lamb waves according to claim 1, wherein: the magnetostrictive material contains 48.94% of iron, 48.75% of cobalt, 0.01% of carbon, 0.05% of silicon, 0.30% of niobium, 0.05% of manganese and 1.90% of vanadium.

4. The magnetostrictive patch sensor for highly efficient excitation of helical circumferential lamb waves according to claim 2, wherein: the length of the flexible printed coil and the magnetostrictive material along the axial direction of the pipeline to be tested is 50mm, and the length along the circumferential direction of the pipeline to be tested is determined according to the diameter of the pipeline to be tested; each section of the horse race field coil is 12mm in width and consists of 12 leads along the axial direction of the pipeline to be tested, and 23 leads are arranged along the circumferential direction of the pipeline to be tested and used for connecting two sections of adjacent horse race field coils; the width of all the wires is 0.9 mm.

5. The method of operating a magnetostrictive patch sensor for highly efficient excitation of a helicoidal circumferential lamb wave according to any of claims 1-4, characterized in that: determining the included angle between the propagation direction of the spirally propagated circumferential lamb wave and the circumferential direction of the pipelineθAnd then, rapidly carrying out axial defect detection on the pipeline based on the circumferential lamb wave of spiral propagation by using a self-excitation self-receiving mode.

6. The method of operating a magnetostrictive patch sensor for highly efficient excitation of a helicoidal circumferential lamb wave according to any of claims 1-4, characterized in that: determining the included angle between the propagation direction of the spirally propagated circumferential lamb wave and the circumferential direction of the pipelineθAnd then, by receiving the circumferential lamb waves at each circumferential position of the pipeline, and utilizing the observed number of defect packets, the screw pitch of the spirally propagated circumferential lamb waves and the relation of the axial range of the defects, the axial position of the defects in the pipeline is evaluated.

7. The method of operating a magnetostrictive patch sensor for highly efficient excitation of a helicoidal circumferential lamb wave according to any of claims 1-4, comprising the steps of:

step S1: adhering the magnetostrictive material to a pipeline;

step S2: adhering the flexible printed coil to a magnetostrictive material;

step S3: inputting a sine wave signal modulated by a Hanning window with 5 cycles through the flexible printed coil by adopting a self-excitation self-receiving mode, and collecting a received signal;

step S4: and observing the defect reflection signal, and calculating the axial position of the axial defect by utilizing the axial propagation speed of the circumferential lamb wave which is spirally propagated, the time corresponding to the defect reflection signal and the relation of the axial position of the defect.

8. The method of operating a magnetostrictive patch sensor for highly efficient excitation of a helicoidal circumferential lamb wave according to claim 7, further comprising the steps of:

step S5: changing the circumferential position of the flexible printed coil on the pipeline, and repeating the steps S3-S4 to collect signals of the whole circumference of the pipeline and obtain the total number of the collected signalsNAs the case may be;

6) summarizing the number of signals including defectsMIncluding the number of defect signalsMAnd total number of collected signalsNIs multiplied by the pitch of the helically propagating circumferential lamb waveπ ∙ D ∙ tanθObtaining an axial length of the defect; wherein D is the outer diameter of the pipeline;θthe included angle between the propagation direction of the spiral propagation circumferential lamb wave and the circumferential direction of the pipeline is formed.

9. The method of operating a magnetostrictive patch sensor for efficient excitation of a helical circumferential lamb wave according to claim 8, wherein: the propagation direction of the spiral propagation circumferential lamb wave forms an included angle with the circumferential direction of the pipelineθObtained by performing simulation calculation through a Matlab program.

Technical Field

The invention belongs to the technical field of nondestructive testing, can be used for positioning axial defects in pipelines and evaluating the axial range of the defects in the pipelines, and particularly relates to a magnetostrictive patch type sensor for efficiently exciting spiral circumferential lamb waves and a working method thereof.

Background

The pipeline not only can finish the transportation of liquid materials such as petroleum, natural gas, finished oil, chemical products, water and the like, but also can convey solid substances such as coal, flour, cement and the like. At present, the total length of pipelines used all over the world reaches 350 kilometers, wherein the number of old pipelines accounts for more than half, how to evaluate the conditions of the pipelines and ensure safe and economic operation is a main problem solved by a pipeline integrity evaluation technology. Pipeline transport leaks result in a lower annual incidence of accidents than other transport means, but pipeline accidents can be catastrophic. The process of detecting a major threat factor that may cause a pipeline to fail and thereby evaluating the suitability of the pipeline is referred to as pipeline integrity management. Pipeline companies in all countries around the world form their own integrity management system. The detection is an important link of the integrity management of the pipeline, and the level of the detection technology directly determines the accuracy of the integrity evaluation.

Ultrasonic guided waves have been widely used in pipeline inspection due to their advantages of high efficiency and long distance. The ultrasonic guided wave in the traditional pipeline is divided into an axial ultrasonic guided wave mode and a circumferential ultrasonic guided wave mode. The two types of ultrasonic guided wave modes are sensitive to different types of defects in the pipeline due to different propagation directions of the two types of ultrasonic guided wave modes. The axial ultrasonic guided wave mode is longer than the circumferential defect detection, and the circumferential ultrasonic guided wave mode is suitable for detecting the axial defect. However, the circumferential mode cannot realize defect scanning of the axial range of the pipeline. In addition, there is little method that can evaluate for the axial extent of defects in the pipe. Therefore, a method for rapidly scanning the axial range defect of the pipeline is needed, which can detect the axial position of the axial defect in the pipeline and evaluate the axial range of the defect in a nondestructive testing method. There is no non-destructive testing method that can quickly detect the axial position of an axial defect in a pipe and assess the axial extent of the defect.

Disclosure of Invention

Aiming at the defects and shortcomings in the prior art, the invention aims to provide a magnetostrictive patch type sensor for efficiently exciting spiral circumferential lamb waves and a working method thereof, so that axial defects in a pipeline can be axially positioned by using the spirally transmitted circumferential lamb waves, and the axial range of the defects in the pipeline can be evaluated. In order to realize the positioning of the axial defects in the pipeline and the evaluation of the circumferential range of the defects, the invention utilizes circumferential lamb waves sensitive to the axial defects to be spirally transmitted along the axial direction of the pipeline, judges the axial positions of the defects according to defect reflection signals in the signals, summarizes the number of the signals with the defect reflection to evaluate the axial length of the defects, and adopts a mode of comparing a theoretical model with an experiment. In addition, the method supports a self-excitation and self-receiving measurement mode, and can adapt to the condition that only one end of a pipeline can be loaded with a sensor in engineering measurement.

The self-excitation and self-receiving axial flaw detection method can be used for rapidly carrying out axial flaw detection on the pipeline based on circumferential lamb waves of spiral propagation by utilizing a self-excitation and self-receiving mode. In addition, the axial position of the defect in the pipeline can be evaluated by receiving the circumferential lamb waves at each circumferential position of the pipeline and utilizing the observed number of defect packets and the relation between the helical pitch of the spirally propagating circumferential lamb waves and the axial range of the defect. The method can be used for solving the axial defects which are difficult to detect by the traditional ultrasonic guided waves in the pipeline and the defect axial range which is difficult to evaluate by the traditional ultrasonic guided waves.

In order to achieve the purpose, the technical scheme of the invention is as follows: 1) adhering a magnetostrictive material to the pipeline; 2) sticking a flexible printed coil which is used for efficiently exciting a spiral transmission circumferential lamb wave on a magnetostrictive material; 3) a self-excitation self-receiving mode is adopted, a sine wave signal modulated by a 5-period Hanning window is input through a high-efficiency excitation spiral transmission circumferential lamb wave flexible printed coil, and a received signal is acquired; 4) and observing the defect reflection signal, and utilizing the axial propagation speed of the circumferential lamb wave which is spirally propagated, the time corresponding to the defect reflection signal and the relation of the axial position of the defect. The axial position of the axial defect is calculated. When the axial extent of the defect needs to be evaluated, two additional steps are required: 5) circumferential lamb for changing high-efficiency excitation spiral propagationThe circumferential position of the flexible printing coil of the wave on the pipeline is repeated, the steps 3) and 4) are repeated, the signals of the whole circumference of the pipeline need to be collected, and the total quantity of the collected signalsNAs the case may be; 6) summarizing the number of signals including defectsM. Including the number of defective signalsMAnd total number of collected signalsNIs multiplied by the pitch of the helically propagating circumferential lamb waveπ ∙ D ∙ tanθIs the axial length of the defect.

The invention specifically adopts the following technical scheme:

a magnetostrictive patch type sensor for efficiently exciting a spiral circumferential lamb wave is characterized by comprising: a flexible printed coil and magnetostrictive material for exciting a helically propagating circumferential lamb wave; the magnetostrictive material is used for being adhered to a pipeline, and the flexible printing coil is adhered to the magnetostrictive material.

Furthermore, the flexible printed coil is divided into two layers, and a circuit of a first layer of the coil comprises a plurality of groups of two-section tramcar field coils which are connected in series; the circuit of the second layer is a lead wire for connecting two adjacent groups of horse race field coils; the terminal of each section of the horse race field coil is provided with a through hole for connecting the first layer circuit and the second layer circuit.

Further, the magnetostrictive material had an iron content of 48.94%, a cobalt content of 48.75%, a carbon content of 0.01%, a silicon content of 0.05%, a niobium content of 0.30%, a manganese content of 0.05%, and a vanadium material content of 1.90%.

Further, the length of the flexible printing coil and the magnetostrictive material along the axial direction of the pipeline to be tested is 50mm, and the length along the circumferential direction of the pipeline to be tested is determined according to the diameter of the pipeline to be tested; each section of the horse race field coil is 12mm in width and consists of 12 leads along the axial direction of the pipeline to be tested, and 23 leads are arranged along the circumferential direction of the pipeline to be tested and used for connecting two sections of adjacent horse race field coils; the width of all the wires is 0.9 mm.

And a method of operating a sensor according to the above preference, characterized by: determining the included angle between the propagation direction of the spirally propagated circumferential lamb wave and the circumferential direction of the pipelineθAnd then, rapidly carrying out axial defect detection on the pipeline based on the circumferential lamb wave of spiral propagation by using a self-excitation self-receiving mode.

And a second method of operating a sensor according to the above preferred embodiment, characterized by: determining the included angle between the propagation direction of the spirally propagated circumferential lamb wave and the circumferential direction of the pipelineθAnd then, by receiving the circumferential lamb waves at each circumferential position of the pipeline, and utilizing the observed number of defect packets, the screw pitch of the spirally propagated circumferential lamb waves and the relation of the axial range of the defects, the axial position of the defects in the pipeline is evaluated.

And a third method of operating a sensor according to the above preferences, comprising the steps of:

step S1: adhering the magnetostrictive material to a pipeline;

step S2: adhering the flexible printed coil to a magnetostrictive material;

step S3: inputting a sine wave signal modulated by a Hanning window with 5 cycles through the flexible printed coil by adopting a self-excitation self-receiving mode, and collecting a received signal;

step S4: and observing the defect reflection signal, and calculating the axial position of the axial defect by utilizing the axial propagation speed of the circumferential lamb wave which is spirally propagated, the time corresponding to the defect reflection signal and the relation of the axial position of the defect.

Further, the method also comprises the following steps:

step S5: changing the circumferential position of the flexible printed coil on the pipeline, and repeating the steps S3-S4 to collect signals of the whole circumference of the pipeline and obtain the total number of the collected signalsNAs the case may be;

6) summarizing the number of signals including defectsMIncluding the number of defect signalsMAnd total number of collected signalsNIs multiplied by the pitch of the helically propagating circumferential lamb waveπ ∙ D ∙ tanθObtaining an axial length of the defect; wherein D is the outer diameter of the pipeline;θthe included angle between the propagation direction of the spiral propagation circumferential lamb wave and the circumferential direction of the pipeline is formed.

Further, the propagation direction of the spirally propagated circumferential lamb wave forms an included angle with the circumferential direction of the pipelineθObtained by performing simulation calculation through a Matlab program.

Compared with the prior art, the invention and the optimized scheme thereof have the following beneficial effects:

1. axial defects which are difficult to detect by traditional ultrasonic guided waves in the pipeline can be detected;

2. the defect axial range which is difficult to evaluate by the traditional ultrasonic guided wave can be evaluated;

3. the pipeline defect detection can be rapidly carried out through a self-excitation self-receiving excitation mode.

Drawings

The invention is described in further detail below with reference to the following figures and detailed description:

fig. 1 is a schematic diagram of a structure and a principle of a spiral circumferential lamb wave magnetostrictive patch sensor according to an embodiment of the invention.

Fig. 2 is a schematic diagram of an actual installation of the spiral circumferential lamb wave magnetostrictive patch sensor according to the embodiment of the invention.

FIG. 3 shows 200kHz spiral circumferential lamb waves and 200kHz spiral circumferential lamb waves at the same wavelength in an embodiment of the inventionL(0,2) 120kHzT(0,1) signal comparison schematic diagram for detecting defects with different axial and circumferential lengths.

FIG. 4 is a schematic diagram of an example of signals for evaluating axial length of a defect in a pipe using a 300kHz spiral circumferential lamb wave in accordance with an embodiment of the invention.

In the figure: 1-flexible printed coil for efficiently exciting spiral propagating circumferential lamb wave, 2-magnetostrictive material.

Detailed Description

In order to make the features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail as follows:

it should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

The terminology used in the present disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

It should be understood that although the terms first, second, and third may be used in this disclosure to describe various information, this information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present disclosure. The word "if" as used herein may be interpreted as "at … …" or "when … …" or "in response to a determination", depending on the context.

The invention is further explained below with reference to the drawings and the embodiments.

As shown in fig. 1 to 4, the scheme provided by the present embodiment mainly includes:

1. a flexible printed coil 1 for efficiently exciting a spirally propagating circumferential lamb wave; 2. a magnetostrictive material 2; 3. determining the included angle between the propagation direction of the spiral propagation circumferential lamb wave and the circumferential direction of the pipelineθThe program of (1).

Based on the composition, the self-excitation self-receiving mode can be utilized to rapidly carry out axial defect detection on the pipeline based on circumferential lamb waves of spiral propagation. In addition, the axial position of the defect in the pipeline can be evaluated by receiving the circumferential lamb waves at each circumferential position of the pipeline and utilizing the observed number of defect packets and the relation between the helical pitch of the spirally propagating circumferential lamb waves and the axial range of the defect. The method can be used for solving the axial defects which are difficult to detect by the traditional ultrasonic guided waves in the pipeline and the defect axial range which is difficult to evaluate by the traditional ultrasonic guided waves. The parts are characterized as follows:

as shown in fig. 1, the present embodiment employs a flexible printed coil width (i.e., axial length) of 50 mm. The length (i.e., circumferential length) depends on the diameter of the pipe to be measured. The coil is divided into two layers. The circuit of the first layer of the coil comprises a plurality of groups of horse race field coils formed by connecting two sections in series. Each section of the horse race field coil is 12mm in width and consists of 12 wires in the width direction. And 23 wires are arranged in the length direction and are used for connecting two adjacent sections of the horserace field coils. The terminal of each section of the horse race field coil is provided with a through hole for connecting the first layer circuit and the second layer circuit. The second layer of circuit is a wire for connecting two adjacent groups of marquee field coils, and two adjacent series-connected marquee field coils of the first layer of circuit are connected by one wire in the second layer of circuit. The width of all the wires is 0.9 mm.

For the magnetostrictive material provided in this example, the content of its components includes: 48.94% of iron, 48.75% of cobalt, 0.01% of carbon, 0.05% of silicon, 0.30% of niobium, 0.05% of manganese and 1.90% of vanadium. The thickness is 0.152 mm;

the embodiment is used for determining the included angle between the propagation direction of the spiral propagation circumferential lamb wave and the circumferential direction of the pipelineθThe program of (a) is the Matlab program.θThe value is a necessary parameter for evaluating the axial length of the defect and can be obtained by establishing model calculation on the sensor scheme of the invention. Propagating a circumferential lamb wave S0 mode helically at 300kHz in a stainless steel tube of 32mm outside diameter and 1mm wall thicknessFor example, the Matlab program for the angle between the propagation direction and the circumferential direction of the pipe gives an angle of 24.75 ° for the point with the largest amplitude in the curve. The procedure was as follows:

f = 300%

a0=0:(pi/2/1000):(pi/2);

for i=1:1001

s(i)=1/sin(a0(i));

end

Ph = 5547.79%% Ph is frequency of spiral propagating circumferential lamb wave

t=s*2/Ph;

for i=1:1001

att(i)=10^(-0.159*s(i));

end

for i=1:1001

att100(i)=10^(-0.05*s(i));

end

for i=1:1001

att500(i)=10^(-0.2598*s(i));

end

L = 25%

z=10000;

for i=1:1001

l0(i)=z/cos(a0(i));

end

X1= -18%

X2=-6;

X3=6;

X4=18;

for i=1:1001

r1(i)=sqrt((l0(i)*sin(a0(i))).^2+(l0(i)*cos(a0(i))-X1).^2);

theta1(i)=atan(l0(i)*sin(a0(i))/(l0(i)*cos(a0(i))-X1));

r2(i)=sqrt((l0(i)*sin(a0(i))).^2+(l0(i)*cos(a0(i))-X2).^2);

theta2(i)=atan(l0(i)*sin(a0(i))/(l0(i)*cos(a0(i))-X2));

r3(i)=sqrt((l0(i)*sin(a0(i))).^2+(l0(i)*cos(a0(i))-X3).^2);

theta3(i)=atan(l0(i)*sin(a0(i))/(l0(i)*cos(a0(i))-X3));

r4(i)=sqrt((l0(i)*sin(a0(i))).^2+(l0(i)*cos(a0(i))-X4).^2);

theta4(i)=atan(l0(i)*sin(a0(i))/(l0(i)*cos(a0(i))-X4));

end

for i=1:1001

si1(i)=sin((2*pi*f/Ph)*L/2*sin(theta1(i)))/((2*pi*f/Ph)*L/2*sin(theta1(i)));

si2(i)=sin((2*pi*f/Ph)*L/2*sin(theta2(i)))/((2*pi*f/Ph)*L/2*sin(theta2(i)));

si3(i)=sin((2*pi*f/Ph)*L/2*sin(theta3(i)))/((2*pi*f/Ph)*L/2*sin(theta3(i)));

si4(i)=sin((2*pi*f/Ph)*L/2*sin(theta4(i)))/((2*pi*f/Ph)*L/2*sin(theta4(i)));

end

si1(1)=1;

si2(1)=1;

si3(1)=1;

si4(1)=1;

for i=1:1001

S1(i)=L*sqrt(2/pi/r1(i)/(2*pi*f/Ph))*(-1)^1*exp(j*(2*pi*f/Ph)*r1(i))*si1(i);

S2(i)=L*sqrt(2/pi/r2(i)/(2*pi*f/Ph))*(-1)^2*exp(j*(2*pi*f/Ph)*r2(i))*si2(i);

S3(i)=L*sqrt(2/pi/r3(i)/(2*pi*f/Ph))*(-1)^3*exp(j*(2*pi*f/Ph)*r3(i))*si3(i);

S4(i)=L*sqrt(2/pi/r4(i)/(2*pi*f/Ph))*(-1)^4*exp(j*(2*pi*f/Ph)*r4(i))*si4(i);

end

for i=1:1001

S01(i)=S1(i)+S2(i)+S3(i)+S4(i);

end

as0=abs(S01);

for i=1:1001

AS0(i)=as0(1002-i);

end

A0=-(pi/2):(pi/2/1000):0;

a0=a0*180/pi;

A0=A0*180/pi;

for i=1:1001

syn(i)=att(i)*as0(i);

end

syn=syn/max(syn);

figure(1)

plot(a0,syn)

ylim([0,1.1])。

With the above design, the specific process of performing the measurement operation in this embodiment includes: 1) adhering a magnetostrictive material to the pipeline; 2) attaching a flexible printed coil which is used for efficiently exciting a spiral propagation circumferential lamb wave to a magnetostrictive material; 3) a self-excitation self-receiving mode is adopted, a sine wave signal modulated by a 5-period Hanning window is input through a high-efficiency excitation spiral transmission circumferential lamb wave flexible printed coil, and a received signal is acquired; 4) and observing the defect reflection signal, and utilizing the axial propagation speed of the circumferential lamb wave which is spirally propagated, the time corresponding to the defect reflection signal and the relation of the axial position of the defect. The axial position of the axial defect is calculated. When the axial extent of the defect needs to be evaluated, two additional steps are required: 5) changing the circumferential position of a flexible printed coil for efficiently exciting the spiral transmission circumferential lamb waves on the pipeline, repeating the steps 3) and 4) to acquire signals of the whole circumferential direction of the pipeline, and acquiring the total number of the signalsNAs the case may be; 6) summarizing the number of signals including defectsM. Including the number of defective signalsMAnd total number of collected signalsNIs multiplied by the pitch of the helically propagating circumferential lamb waveπ ∙ D ∙ tanθIs the axial length of the defect.

As shown in fig. 2, two specific examples are provided below:

helical propagating circumferential lamb wave localization axial defect examples:

1) adhering a magnetostrictive material with the width of 50mm and the length equivalent to the circumference of the pipeline on the pipeline;

2) attaching a flexible printed coil which is used for efficiently exciting a spiral propagation circumferential lamb wave to a magnetostrictive material;

3) a self-excitation self-receiving mode is adopted, sine wave signals modulated by a 5-period Hanning window are input through a flexible printed coil which efficiently excites a spiral to transmit circumferential lamb waves, and received signals are collected;

4) and observing the defect reflection signal, and utilizing the axial propagation speed of the circumferential lamb wave which is spirally propagated, the time corresponding to the defect reflection signal and the relation of the axial position of the defect. The axial position of the axial defect is calculated.

Helical propagating circumferential lamb wave evaluation defect axial range example:

1) adhering a magnetostrictive material with the width of 50mm and the length equivalent to the circumference of the pipeline on the pipeline;

2) attaching a flexible printed coil which is used for efficiently exciting a spiral propagation circumferential lamb wave to a magnetostrictive material, wherein the coverage range is half of the circumferential direction of the pipeline;

3) a self-excitation self-receiving mode is adopted, sine wave signals modulated by a 5-period Hanning window are input through a flexible printed coil which efficiently excites a spiral to transmit circumferential lamb waves, and received signals are collected;

4) and observing the defect reflection signal, and utilizing the axial propagation speed of the circumferential lamb wave which is spirally propagated, the time corresponding to the defect reflection signal and the relation of the axial position of the defect. Calculating the axial position of the axial defect;

5) changing the circumferential position of a flexible printed coil which efficiently excites spiral propagation circumferential lamb waves on the pipeline, repeating the steps 3) and 4) and needing to acquire signals of the whole circumferential direction of the pipeline, wherein the total acquired signal number N is determined according to the situation;

6) summarizing the number of signals including defectsM. Including the number of defective signalsMAnd total number of collected signalsNIs multiplied by the pitch of the helically propagating circumferential lamb waveπ ∙ D ∙ tanθIs the axial length of the defect.

The following test results were obtained using the above test protocol: as shown in FIG. 3, the frequency of the 200kHz spiral circumferential lamb wave and the frequency of the 200kHz spiral circumferential lamb wave are the sameL(0,2) 120kHzT(0,1) signal comparison schematic diagram for detecting defects with different axial and circumferential lengths.

As shown in FIG. 4, a schematic representation of an example of a signal for evaluating the axial length of a defect in a pipe for a 300kHz helical circumferential lamb wave.

The above test results demonstrate the efficacy of the present embodiment.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.

The patent is not limited to the preferred embodiments, and other various shapes can be derived by anyone based on the teaching of the patent

The magnetostrictive patch sensor for efficiently exciting spiral circumferential lamb waves and the working method thereof belong to the coverage of the patent when the equivalent change and modification are carried out according to the patent application range of the invention.