Structural defect detection method and system based on frequency mixing ultrasonic delay excitation

Abstract

The invention provides a structural defect detection method and system based on mixing ultrasonic delay excitation, four piezoelectric ceramic sensors are arranged on the surface of a composite material layer in a rectangular shape, mixing sound waves received by the two piezoelectric ceramic sensors are subjected to band-pass filtering, EMD decomposition and reconstruction and frequency spectrum-energy spectrum analysis in sequence, and the frequency spectrum-energy spectrum analysis result is obtained. Extracting modulation sideband parameters from the time-frequency spectrum, and calculating defect identification parameters according to the modulation sideband parameters; if the defect identification parameter is greater than zero, determining that a defect exists in the modulation aliasing region under the excitation delay time; if the defect identification parameter is less than zero, determining that no defect exists in the modulation aliasing region under the excitation delay time; based on a frequency mixing excitation mode of delayed excitation of low-frequency pumping waves and high-frequency detection waves, frequency mixing incident waves do not need to be on the same axis, a sound wave aliasing area can be indirectly adjusted, and therefore large-range comprehensive scanning of the structure is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material defect detection, and in particular to a method and system for detecting structural defects by mixed-frequency ultrasonic delayed excitation. Background Art

[0002] The statements in this section merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] Composite materials are widely used in aircraft, rockets, bridges, pipelines, automobiles and other fields due to their high strength and light weight. They can not only reduce the weight of equipment, but also have the advantages of corrosion resistance, anti-aging, anti-fatigue, etc., which can greatly extend the service life of equipment structures. However, due to improper manufacturing process or defects in the material itself, composite materials often have interlayer defects (for example, interlayer separation, interlayer gaps, interlayer impurities, etc.), which will cause insufficient bonding strength between layers, and shear bearing capacity failure is prone to occur under external loads, and even cause huge economic losses or major safety accidents. Therefore, effective identification and positioning of interlayer defects in composite materials is crucial to ensure the safe operation of equipment. Delamination, peeling and other defects inside the structure can generally be identified by ultrasonic detection technology, thermal imaging technology, etc. However, when the delamination is in a very early stage, the transmission coefficient of the defect is very similar to that of the well-bonded area, resulting in the above-mentioned traditional detection technology may not be able to detect the early defect. Therefore, the development of an effective method for identifying and locating structural interlayer defects is a huge challenge in the field of non-destructive testing and structural health monitoring.

[0004] Ultrasonic guided waves are formed by multiple reciprocating reflections and further coupling of elastic waves in the structure. They can propagate throughout the thickness of the thin plate structure. They have the advantages of high speed, high damage sensitivity, and the ability to monitor in-service structures in real time. They have attracted much attention in recent years. Ultrasonic guided wave detection technology can be divided into linear ultrasonic detection methods and nonlinear ultrasonic detection methods. Among them, the linear ultrasonic detection method is based on the principles of sound wave diffraction, reflection and transmission. It characterizes the damage of engineering components by obtaining parameters such as sound velocity and attenuation. It is only suitable for detecting macroscopic delamination damage and has great limitations in the identification of early interlayer defects.

[0005] Nonlinear ultrasonic testing technology can effectively overcome the shortcomings of linear ultrasonic testing technology that is not suitable for early micro-damage detection. By measuring nonlinear parameters such as harmonics and sidebands, it can effectively reflect the early performance degradation of materials and the initiation and evolution of early damage. Studies have shown that the nonlinear components caused by interlayer defects are more significant, and nonlinear mixing acoustic modulation detection technology can significantly stimulate the weak nonlinear effect at the nearly perfect damage interface. In addition, nonlinear mixing acoustic modulation detection technology can be divided into two categories: collinear mixing detection technology and non-collinear mixing detection technology. This technology has obvious advantages such as frequency selectability, direction controllability, and spatial selection, which can significantly improve the detection accuracy and help to achieve damage location. However, the collinear mixing method requires two columns of incident waves on the same axis and has high accuracy requirements, which is difficult to implement. Summary of the invention

[0006] In order to address the shortcomings of the prior art, the present invention provides a structural defect detection method and system with mixed ultrasonic delayed excitation, which is based on a mixed excitation method with delayed excitation of a low-frequency pump wave and a high-frequency detection wave. It does not require the mixed incident waves to be on the same axis, and can indirectly adjust the sound wave aliasing area, thereby achieving a large-scale comprehensive scanning of the structure.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for detecting structural defects by mixed-frequency ultrasonic delayed excitation.

[0009] A structural defect detection device with mixed-frequency ultrasonic delayed excitation, comprising four piezoelectric ceramic sensors arranged in a rectangular shape and fixed on a surface of a structure, the four piezoelectric ceramic sensors are all communicatively connected to a control terminal, two piezoelectric ceramic sensors on a first side of the rectangle serve as excitation ends, and two piezoelectric ceramic sensors on a second side of the rectangle serve as receiving ends;

[0010] The first piezoelectric ceramic sensor at the excitation end is used to emit a high-frequency detection wave according to the control signal of the control terminal, and the second piezoelectric ceramic sensor at the excitation end is used to emit a low-frequency pump wave according to the control signal of the control terminal. The high-frequency detection wave has an excitation delay time relative to the low-frequency pump wave.

[0011] The position coordinate when the front end of the high-frequency detection wave meets the end of the excited low-frequency pump wave is the first coordinate, at which time the high-frequency detection wave interacts with the low-frequency pump wave and generates a mixed-frequency sound wave; the position coordinate when the end of the high-frequency detection wave meets the front end of the excited low-frequency pump wave is the second coordinate, at which time the high-frequency detection wave and the low-frequency pump wave separate from each other and no longer generate a mixed-frequency sound wave;

[0012] The control terminal is configured to: perform defect detection in a modulation aliasing area between the first coordinate and the second coordinate according to the mixed frequency sound waves received by the two piezoelectric ceramic sensors at the receiving end.

[0013] In a second aspect, the present invention provides a method for detecting structural defects by mixed-frequency ultrasonic delayed excitation.

[0014] A method for detecting structural defects by mixed-frequency ultrasonic delayed excitation, using the device for detecting structural defects by mixed-frequency ultrasonic delayed excitation according to the first aspect of the present invention, comprises the following steps:

[0015] The mixed sound waves received by the two piezoelectric ceramic sensors are subjected to bandpass filtering, EMD decomposition and reconstruction, and spectrum-energy spectrum analysis in turn, and the modulation sideband parameters are extracted from the time-frequency spectrum, and the defect identification parameters are calculated based on the modulation sideband parameters.

[0016] If the defect identification parameter is greater than zero, there is a defect in the modulation aliasing region under the excitation delay time; if the defect identification parameter is less than zero, there is no defect in the modulation aliasing region under the excitation delay time.

[0017] As a further limitation of the second aspect of the present invention, the defect identification parameter γ is: Among them, β Rec1 represents the modulation sideband parameter corresponding to the response signal of the low-frequency pump wave, β Rec2 Represents the modulation sideband parameters corresponding to the response signal of the high-frequency detection wave.

[0018] As a further limitation of the second aspect of the present invention, taking the center point of the first piezoelectric ceramic sensor as the origin, the horizontal line on the rectangle as the X-axis, and the vertical line on the rectangle as the Y-axis, the first coordinate is (x1, y1), and the second coordinate is (x2, y2);

[0019] If the defect identification parameter is greater than zero, a defect exists between the modulation aliasing region x1 and x2 on the X-axis under the set delay time.

[0020] As a further limitation of the second aspect of the present invention, the front end of the high-frequency detection wave meets the end of the excited low-frequency pump wave, and the trajectory is:

[0021]

[0022] Among them, d a is the distance between the first piezoelectric ceramic sensor and the second piezoelectric ceramic sensor, the two piezoelectric ceramic sensors on the second side of the rectangle are the third piezoelectric ceramic sensor and the fourth piezoelectric ceramic sensor, the first piezoelectric ceramic sensor and the third piezoelectric ceramic sensor are collinear, d b is the distance between the first piezoelectric ceramic sensor and the third piezoelectric ceramic sensor, d b1 is the distance between the first piezoelectric ceramic sensor and the encounter position. At this time, d b1= x1, △t is the delayed excitation time of the high-frequency detection wave, λ L is the wavelength of the low-frequency pump wave, C g_L is the group velocity of the low-frequency pump wave, C g_H is the group velocity of the high-frequency probe wave;

[0023] The end of the high-frequency probe wave meets the front end of the excited low-frequency pump wave, and the trajectory is:

[0024]

[0025] Among them, d b1 is the distance between the first piezoelectric ceramic sensor and the encounter position. At this time, d b1 = x2,λ H is the wavelength of the high-frequency detection wave;

[0026] According to the trajectory at the first moment, the trajectory at the second moment, and the excitation delay time corresponding to when the defect recognition parameter is greater than zero, combined with the sound wave propagation speed, the values ​​of x1 and x2 are solved.

[0027] In a third aspect, the present invention provides a structural defect detection system using mixed-frequency ultrasonic delayed excitation.

[0028] A mixed-frequency ultrasonic delayed excitation structural defect detection system, using the mixed-frequency ultrasonic delayed excitation structural defect detection device according to the first aspect of the present invention, comprises the following process:

[0029] The defect recognition parameter calculation unit is configured to: perform bandpass filtering, EMD decomposition and reconstruction, and spectrum-energy spectrum analysis on the mixed sound waves received by the two piezoelectric ceramic sensors in sequence, extract modulation sideband parameters from the time-frequency spectrum, and calculate the defect recognition parameters according to the modulation sideband parameters;

[0030] The damage detection unit is configured as follows: if the defect identification parameter is greater than zero, there is a defect in the modulation aliasing area under the excitation delay time; if the defect identification parameter is less than zero, there is no defect in the modulation aliasing area under the excitation delay time.

[0031] In a fourth aspect, the present invention provides a computer device, comprising: a processor and a computer-readable storage medium;

[0032] a processor adapted to execute a computer program;

[0033] A computer-readable storage medium having a computer program stored therein, wherein when the computer program is executed by the processor, the method for detecting structural defects by delayed excitation of mixed-frequency ultrasonic waves as described in the second aspect of the present invention is implemented.

[0034] In a fifth aspect, the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program is suitable for being loaded by a processor and executing the structural defect detection method using mixed-frequency ultrasonic delayed excitation as described in the second aspect of the present invention.

[0035] In a sixth aspect, the present invention provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the structural defect detection method using mixed-frequency ultrasonic delayed excitation as described in the second aspect of the present invention.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The present invention innovatively proposes a structural defect detection method and system with mixed ultrasonic delayed excitation, which is based on the mixed excitation mode of delayed excitation of low-frequency pump wave and high-frequency detection wave. It does not require the mixed incident waves to be on the same axis, and can indirectly adjust the sound wave aliasing area, thereby realizing a large-scale comprehensive scanning of the structure.

[0038] 2. Based on the typical nonlinear acoustic characteristics of modulation sideband, the present invention constructs an “excitation delay time △t i -defect identification parameter γ” mapping model is used for damage identification and location, which can eliminate the influence of system nonlinearity and overcome the dependence on healthy reference signals, and has broad engineering application prospects.

[0039] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0041] Figure 1 A schematic diagram of a structural defect detection method based on mixed-frequency ultrasonic delayed excitation provided in Example 1 of the present invention;

[0042] Figure 2 A schematic diagram of an ultrasonic aliasing region based on frequency mixing ultrasonic delayed excitation provided in Example 1 of the present invention;

[0043] Figure 3 A schematic diagram of a structural defect detection method using mixed-frequency ultrasonic delayed excitation provided in Example 1 of the present invention;

[0044] Figure 4 A schematic diagram of an electronic device provided in Embodiment 4 of the present invention. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0046] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0047] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0048] Embodiment 1:

[0049] This implementation method proposes a structural defect detection device based on mixed-frequency ultrasonic delayed excitation, such as Figure 1 and Figure 2 As shown, four piezoelectric ceramic sensors are pasted on the surface of the adhesive structure to form a rectangular excitation-sensing network (a piezoelectric ceramic sensor is arranged at each of the four corner points of the rectangle); wherein the piezoelectric ceramic sensors on the right (the first piezoelectric ceramic sensor and the second piezoelectric ceramic sensor from top to bottom) serve as excitation ends to excite ultrasonic waves, and the piezoelectric ceramic sensors on the left (the third piezoelectric ceramic sensor and the fourth piezoelectric ceramic sensor from top to bottom) serve as receiving ends to receive ultrasonic response signals.

[0050] In this implementation, for non-collinear mixing detection, the traditional acoustic modulation technology is improved by delaying the excitation of the low-frequency pump wave and the high-frequency detection wave, that is, the excitation time of the high-frequency detection wave HF excited by Act1 (i.e., the first piezoelectric ceramic sensor) is delayed by △t relative to the low-frequency pump wave LF excited by Act2 (i.e., the second piezoelectric ceramic sensor). i (i=1,2…m), respectively collect the corresponding mixing response signals Res1 and Res2.

[0051] It also includes a control terminal, which is respectively connected to the four piezoelectric ceramic sensors for controlling the first piezoelectric ceramic sensor to emit a high-frequency detection wave HF and controlling the second piezoelectric ceramic sensor to emit a low-frequency pump wave LF, and for performing defect detection in the modulation aliasing area between the first coordinate and the second coordinate based on the mixed sound waves received by the two piezoelectric ceramic sensors at the receiving end.

[0052] Embodiment 2:

[0053] This implementation is based on the structural defect detection device based on mixed-frequency ultrasonic delayed excitation described in Example 1, and provides a specific structural defect detection method based on mixed-frequency ultrasonic delayed excitation, including the following process:

[0054] When t = 0, the low frequency pump wave LF is excited in the aluminum plate, and the group velocity is C g-L ;

[0055] When t=△t i When the high-frequency detection wave HF is excited, the group velocity is C g-H ;

[0056] Assume that when t=t1, the front end of the excited high-frequency detection wave HF meets the end of the excited low-frequency pump wave LF, and the meeting position coordinates are (x1, y1). The two will interact and generate mixed sound waves. At this time, the motion trajectory of the front end of the high-frequency detection wave H and the motion trajectory of the end of the low-frequency detection wave L are combined to obtain:

[0057]

[0058] Among them, d a d b and d b1 The distances between Act1 (i.e., the first piezoelectric ceramic sensor) and Act2 (i.e., the second piezoelectric ceramic sensor), the distance between Act1 (i.e., the first piezoelectric ceramic sensor) and Rec1 (i.e., the third piezoelectric ceramic sensor), and the distance between Act1 (i.e., the first piezoelectric ceramic sensor) and the meeting position (at this time, d b1 =x1), △t is the delayed excitation time of the high-frequency detection wave H, λ L is the wavelength of the low-frequency pump wave L.

[0059] Assume that when t=t2, the end of the excited high-frequency detection wave H meets the front end of the excited low-frequency pump wave L, and the meeting position coordinates are (x2, y2). At this time, the motion trajectory equation of the end of the high-frequency detection wave H and the motion trajectory equation of the front end of the low-frequency pump wave L are combined to obtain:

[0060]

[0061] Among them, d b1 is the distance between Act1 (i.e., the first piezoelectric ceramic sensor) and the encounter position (at this time, d b1 =x2), λ H is the wavelength of the high-frequency pump wave H. After this moment, since the group velocity of the high-frequency detection wave H is higher than the group velocity of the low-frequency pump wave L, the two are separated from each other and there is no mixing area anymore.

[0062] In the process of scanning in sequence, Figure 3 As shown, for each group of i mixing response signals (i.e., Res1 and Res2) collected by non-collinear mixing detection, bandpass filtering, EMD decomposition and reconstruction, and frequency-energy spectrum analysis are performed, and the modulation sideband parameters are extracted from the time-frequency spectrum to calculate the defect identification parameter γ:

[0063]

[0064] Among them, β Rec1 and β Rec2 Respectively represent the modulation sideband parameters in the response signals Res1 and Res2, and the calculation method of the two is as follows:

[0065]

[0066] Among them, A H±nL , A L and A H Represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum, and calculate β Rec1 When A H±nL , A L and A H Respectively represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum of the response signal Res1, and calculate β Rec2 When A H±nL , A L and A H They respectively represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum of the response signal Res2.

[0067] In this implementation, according to different excitation delay times, the “excitation delay time △t i -defect identification parameter γ" mapping model, according to the positive and negative and change trend of parameter γ, damage can be identified and detected without reference. Specifically, if γ>0, it means that the excitation delay time △t i If γ<0, it means that the excitation delay time △t i In this case, there are no defects in the modulation aliasing region.

[0068] In this implementation, further, the excitation delay time △t corresponding to γ>0 is extracted i , combined with the sound wave propagation speed, the fzero function in Matlab software can be used to solve x1 and x2, and the position of the damage in the x-axis direction (that is, between x1 and x2) can be determined, thereby locating the damage.

[0069] Embodiment 3:

[0070] This implementation is based on the structural defect detection device based on mixed-frequency ultrasonic delayed excitation described in Example 1, and provides a structural defect detection system based on mixed-frequency ultrasonic delayed excitation. The structural defect detection device based on mixed-frequency ultrasonic delayed excitation described in the first aspect of the present invention includes the following processes:

[0071] The defect recognition parameter calculation unit is configured to: perform bandpass filtering, EMD decomposition and reconstruction, and spectrum-energy spectrum analysis on the mixed sound waves received by the two piezoelectric ceramic sensors in sequence, extract modulation sideband parameters from the time-frequency spectrum, and calculate the defect recognition parameters according to the modulation sideband parameters;

[0072] The damage detection unit is configured as follows: if the defect identification parameter is greater than zero, there is a defect in the modulation aliasing area under the excitation delay time; if the defect identification parameter is less than zero, there is no defect in the modulation aliasing area under the excitation delay time.

[0073] Specifically, in the defect identification parameter calculation unit, bandpass filtering, EMD decomposition and reconstruction, and frequency-energy spectrum analysis are performed on each group of i mixing response signals (i.e., Res1 and Res2) collected by non-collinear mixing detection, and the modulation sideband parameters are extracted from the time-frequency spectrum to calculate the defect identification parameter γ: β Rec1 and β Rec2 Respectively represent the modulation sideband parameters in the response signals Res1 and Res2, and the calculation method of the two is: Among them, A H±nL , A L and A H Represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum, and calculate β Rec1 When A H±nL , A L and A H Respectively represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum of the response signal Res1, and calculate β Rec2 When A H±nL , A L and A H They respectively represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum of the response signal Res2.

[0074] Specifically, in the damage detection unit, according to different excitation delay times, the “excitation delay time △t i -defect identification parameter γ" mapping model, according to the positive and negative and change trend of parameter γ, damage can be identified and detected without reference. Specifically, if γ>0, it means that the excitation delay time △t i If γ<0, it means that the excitation delay time △t i In this case, there are no defects in the modulation aliasing region.

[0075] In this implementation, further, the excitation delay time △t corresponding to γ>0 is extracted i, combined with the sound wave propagation speed, the fzero function in Matlab software can be used to solve x1 and x2, and the position of the damage in the x-axis direction (that is, between x1 and x2) can be determined, thereby locating the damage.

[0076] It is understandable that the above-mentioned units can be separately or completely combined into one or several other units to constitute, or one (some) of the units can be further divided into multiple functionally smaller units to constitute, which can achieve the same operation without affecting the realization of the technical effects of the embodiments of the present application. The above-mentioned units are divided based on logical functions. In practical applications, the functions of one unit can also be implemented by multiple units, or the functions of multiple units can be implemented by one unit. In other embodiments of the present application, the defect detection system may also include other units. In practical applications, these functions can also be implemented with the assistance of other units, and can be implemented by the collaboration of multiple units.

[0077] According to another embodiment of the present application, the system described in this embodiment can be constructed and the defect detection method of the embodiment of the present application can be implemented by running a computer program (including program code) capable of executing the steps involved in the corresponding method described in Example 2 on a general computing device such as a computer including processing elements and storage elements such as a central processing unit (CPU), random access memory (RAM), and read-only memory (ROM). The computer program can be recorded on, for example, a computer-readable recording medium, and loaded into the above-mentioned computing device through the computer-readable recording medium and run therein.

[0078] Embodiment 4:

[0079] like Figure 4 As shown, this implementation method provides an electronic device (which can be used as the control terminal in Example 1), which includes a processor 1001, a communication interface 1002 and a computer-readable storage medium 1003, wherein the processor 1001, the communication interface 1002 and the computer-readable storage medium 1003 can be connected via a bus or other methods.

[0080] Among them, the communication interface 1002 is used to receive and send data, the computer-readable storage medium 1003 can be stored in the memory of the electronic device, the computer-readable storage medium 1003 is used to store a computer program, the computer program includes program instructions, and the processor 1001 is used to execute the program instructions stored in the computer-readable storage medium 1003.

[0081] Processor 1001 (or CPU (Central Processing Unit)) is the computing core and control core of the electronic device, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions to implement corresponding method processes or corresponding functions.

[0082] The processor 1001 is configured to execute the following process:

[0083] S1: After performing bandpass filtering, EMD decomposition and reconstruction, and spectrum-energy spectrum analysis on the mixed sound waves received by the two piezoelectric ceramic sensors, the modulation sideband parameters are extracted from the time-frequency spectrum, and the defect recognition parameters are calculated based on the modulation sideband parameters;

[0084] S2: If the defect identification parameter is greater than zero, there is a defect in the modulation aliasing region under the excitation delay time; if the defect identification parameter is less than zero, there is no defect in the modulation aliasing region under the excitation delay time.

[0085] Specifically, in step S1, bandpass filtering, EMD decomposition and reconstruction, and frequency-energy spectrum analysis are performed on each group of i mixing response signals (i.e., Res1 and Res2) collected by non-collinear mixing detection, and modulation sideband parameters are extracted from the time-frequency spectrum to calculate the defect identification parameter γ: β Rec1 and β Rec2 Respectively represent the modulation sideband parameters in the response signals Res1 and Res2, and the calculation method of the two is: Among them, A H±nL , A L and A H Represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum, and calculate β Rec1 When A H±nL , A L and A H Respectively represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum of the response signal Res1, and calculate β Rec2 When A H±nL , A L and A H They respectively represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum of the response signal Res2.

[0086] Specifically, in step S2, according to different excitation delay times, the “excitation delay time △t i -defect identification parameter γ" mapping model, according to the positive and negative and change trend of parameter γ, damage can be identified and detected without reference. Specifically, if γ>0, it means that the excitation delay time △t iIf γ<0, it means that the excitation delay time △t i In this case, there are no defects in the modulation aliasing region.

[0087] In this implementation, further, the excitation delay time △t corresponding to γ>0 is extracted i , combined with the sound wave propagation speed, the fzero function in Matlab software can be used to solve x1 and x2, and the position of the damage in the x-axis direction (that is, between x1 and x2) can be determined, thereby locating the damage.

[0088] Embodiment 4:

[0089] This implementation provides a computer-readable storage medium (which can be embedded in the control terminal in Example 1), which is a memory device in an electronic device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in the electronic device and, of course, extended storage media supported by the electronic device. The computer-readable storage medium provides a storage space that stores the processing system of the electronic device.

[0090] In addition, the storage space also stores one or more instructions suitable for being loaded and executed by the processor, and these instructions may be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here may be a high-speed RAM memory, or a non-volatile memory (non-volatile memory), such as at least one disk storage; optionally, it may also be at least one computer-readable storage medium located away from the aforementioned processor.

[0091] In one embodiment, the computer-readable storage medium stores one or more instructions; the processor loads and executes the one or more instructions stored in the computer-readable storage medium to implement the following process:

[0092] S1: After performing bandpass filtering, EMD decomposition and reconstruction, and spectrum-energy spectrum analysis on the mixed sound waves received by the two piezoelectric ceramic sensors, the modulation sideband parameters are extracted from the time-frequency spectrum, and the defect recognition parameters are calculated based on the modulation sideband parameters;

[0093] S2: If the defect identification parameter is greater than zero, there is a defect in the modulation aliasing region under the excitation delay time; if the defect identification parameter is less than zero, there is no defect in the modulation aliasing region under the excitation delay time.

[0094] Specifically, in step S1, bandpass filtering, EMD decomposition and reconstruction, and frequency-energy spectrum analysis are performed on each group of i mixing response signals (i.e., Res1 and Res2) collected by non-collinear mixing detection, and modulation sideband parameters are extracted from the time-frequency spectrum to calculate the defect identification parameter γ: β Rec1 and β Rec2 Respectively represent the modulation sideband parameters in the response signals Res1 and Res2, and the calculation method of the two is: Among them, A H±nL , A L and A H Represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum, and calculate β Rec1 When A H±nL , A L and A H Respectively represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum of the response signal Res1, and calculate β Rec2 When A H±nL , A L and A H They respectively represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum of the response signal Res2.

[0095] Specifically, in step S2, according to different excitation delay times, the “excitation delay time △t i -defect identification parameter γ" mapping model, according to the positive and negative and change trend of parameter γ, damage can be identified and detected without reference. Specifically, if γ>0, it means that the excitation delay time △t i If γ<0, it means that the excitation delay time △t i In this case, there are no defects in the modulation aliasing region.

[0096] In this implementation, further, the excitation delay time △t corresponding to γ>0 is extracted i , combined with the sound wave propagation speed, the fzero function in Matlab software can be used to solve x1 and x2, and the position of the damage in the x-axis direction (that is, between x1 and x2) can be determined, thereby locating the damage.

[0097] Embodiment 5:

[0098] This implementation provides a computer program product or a computer program (which can be embedded in the control terminal in Embodiment 1), the computer program product or the computer program includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. The processor of the electronic device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the electronic device performs the following process:

[0099] S1: After performing bandpass filtering, EMD decomposition and reconstruction, and spectrum-energy spectrum analysis on the mixed sound waves received by the two piezoelectric ceramic sensors, the modulation sideband parameters are extracted from the time-frequency spectrum, and the defect recognition parameters are calculated based on the modulation sideband parameters;

[0100] S2: If the defect identification parameter is greater than zero, there is a defect in the modulation aliasing region under the excitation delay time; if the defect identification parameter is less than zero, there is no defect in the modulation aliasing region under the excitation delay time.

[0101] Specifically, in step S1, bandpass filtering, EMD decomposition and reconstruction, and frequency-energy spectrum analysis are performed on each group of i mixing response signals (i.e., Res1 and Res2) collected by non-collinear mixing detection, and modulation sideband parameters are extracted from the time-frequency spectrum to calculate the defect identification parameter γ: β Rec1 and β Rec2 Respectively represent the modulation sideband parameters in the response signals Res1 and Res2, and the calculation method of the two is: Among them, A H±nL , A L and A H Represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum, and calculate β Rec1 When A H±nL , A L and A H Respectively represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum of the response signal Res1, and calculate β Rec2 When A H±nL , A L and A H They respectively represent the energy of the sideband, low-frequency and high-frequency components in the response spectrum of the response signal Res2.

[0102] Specifically, in step S2, according to different excitation delay times, the “excitation delay time △t i -defect identification parameter γ" mapping model, according to the positive and negative and change trend of parameter γ, damage can be identified and detected without reference. Specifically, if γ>0, it means that the excitation delay time △t iIf γ<0, it means that the excitation delay time △t i In this case, there are no defects in the modulation aliasing region.

[0103] In this implementation, further, the excitation delay time △t corresponding to γ>0 is extracted i , combined with the sound wave propagation speed, the fzero function in Matlab software can be used to solve x1 and x2, and the position of the damage in the x-axis direction (that is, between x1 and x2) can be determined, thereby locating the damage.

[0104] A person skilled in the art can appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0105] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loading and executing computer program instructions on a computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable device. The computer instruction can be stored in a computer-readable storage medium or transmitted by a computer-readable storage medium. The computer instruction can be transmitted from a website site, a computer, a server or a data center to another website site, a computer, a server or a data center by wired (for example, coaxial cable, optical fiber, digital line (DSL)) or wireless (for example, infrared, wireless, microwave, etc.) mode. The computer-readable storage medium can be any available medium that a computer can access or a data processing device such as a server, a data center, etc. that contains one or more available media integration. Available media can be magnetic media (for example, floppy disk, hard disk, tape), optical media (for example, DVD), or semiconductor media (for example, solid-state drive (Solid State Disk, SSD)) and the like.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A structural defect detection device using mixed-frequency ultrasonic delayed excitation, characterized in that: It includes four piezoelectric ceramic sensors arranged in a rectangular shape and fixed on the surface of the structure, and the four piezoelectric ceramic sensors are all connected to the control terminal for communication, the two piezoelectric ceramic sensors on the first side of the rectangle serve as excitation ends, and the two piezoelectric ceramic sensors on the second side of the rectangle serve as receiving ends; The first piezoelectric ceramic sensor at the excitation end is used to emit a high-frequency detection wave according to the control signal of the control terminal, and the second piezoelectric ceramic sensor at the excitation end is used to emit a low-frequency pump wave according to the control signal of the control terminal. The high-frequency detection wave has an excitation delay time relative to the low-frequency pump wave. The position coordinate when the front end of the high-frequency detection wave meets the end of the excited low-frequency pump wave is the first coordinate, at which time the high-frequency detection wave interacts with the low-frequency pump wave and generates a mixed-frequency sound wave; the position coordinate when the end of the high-frequency detection wave meets the front end of the excited low-frequency pump wave is the second coordinate, at which time the high-frequency detection wave and the low-frequency pump wave separate from each other and no longer generate a mixed-frequency sound wave; The control terminal is configured to: perform defect detection in a modulation aliasing area between the first coordinate and the second coordinate according to the mixed frequency sound waves received by the two piezoelectric ceramic sensors at the receiving end.

2. A method for detecting structural defects by mixed-frequency ultrasonic delayed excitation, characterized in that: The structural defect detection device using the mixed-frequency ultrasonic delayed excitation according to claim 1 comprises the following process: The mixed sound waves received by the two piezoelectric ceramic sensors are subjected to bandpass filtering, EMD decomposition and reconstruction, and spectrum-energy spectrum analysis in turn, and the modulation sideband parameters are extracted from the time-frequency spectrum, and the defect identification parameters are calculated based on the modulation sideband parameters. If the defect identification parameter is greater than zero, then there is a defect in the modulation aliasing region at the excitation delay time; If the defect identification parameter is less than zero, there is no defect in the modulation aliasing region under the excitation delay time.

3. The structural defect detection method of mixed-frequency ultrasonic delayed excitation according to claim 2, characterized in that: The defect identification parameter γ is: Among them, β Rec1 represents the modulation sideband parameter corresponding to the response signal of the low-frequency pump wave, β Rec2 Represents the modulation sideband parameters corresponding to the response signal of the high-frequency detection wave.

4. The structural defect detection method of mixed-frequency ultrasonic delayed excitation according to claim 2, characterized in that: Taking the center point of the first piezoelectric ceramic sensor as the origin, the horizontal line on the rectangle as the X-axis, and the vertical line on the rectangle as the Y-axis, the first coordinate is (x1, y1), and the second coordinate is (x2, y2); If the defect identification parameter is greater than zero, a defect exists between the modulation aliasing region x1 and x2 on the X-axis under the set delay time.

5. The structural defect detection method of mixed-frequency ultrasonic delayed excitation according to claim 4, characterized in that: The front end of the high-frequency probe wave meets the end of the excited low-frequency pump wave, and the trajectory is: Among them, d a is the distance between the first piezoelectric ceramic sensor and the second piezoelectric ceramic sensor, the two piezoelectric ceramic sensors on the second side of the rectangle are the third piezoelectric ceramic sensor and the fourth piezoelectric ceramic sensor, the first piezoelectric ceramic sensor and the third piezoelectric ceramic sensor are collinear, d b is the distance between the first piezoelectric ceramic sensor and the third piezoelectric ceramic sensor, d b1 is the distance between the first piezoelectric ceramic sensor and the encounter position. At this time, d b1 = x1, △t is the delayed excitation time of the high-frequency detection wave, λ L is the wavelength of the low-frequency pump wave, C g_L is the group velocity of the low-frequency pump wave; The end of the high-frequency probe wave meets the front end of the excited low-frequency pump wave, and the trajectory is: Among them, d b1 is the distance between the first piezoelectric ceramic sensor and the encounter position. At this time, d b1 = x2,λ H is the wavelength of the high-frequency detection wave; According to the trajectory at the first moment, the trajectory at the second moment, and the excitation delay time corresponding to when the defect recognition parameter is greater than zero, combined with the sound wave propagation speed, the values ​​of x1 and x2 are solved.

6. A structural defect detection system using mixed-frequency ultrasonic delayed excitation, characterized in that: The structural defect detection device using the mixed-frequency ultrasonic delayed excitation according to claim 1 comprises the following process: The defect recognition parameter calculation unit is configured to: perform bandpass filtering, EMD decomposition and reconstruction, and spectrum-energy spectrum analysis on the mixed sound waves received by the two piezoelectric ceramic sensors in sequence, extract modulation sideband parameters from the time-frequency spectrum, and calculate the defect recognition parameters according to the modulation sideband parameters; The damage detection unit is configured such that: if the defect identification parameter is greater than zero, a defect exists in the modulation aliasing region at the excitation delay time; If the defect identification parameter is less than zero, there is no defect in the modulation aliasing region under the excitation delay time.

7. The structural defect detection system of mixed-frequency ultrasonic delayed excitation according to claim 6, characterized in that: In the defect identification parameter calculation unit, the defect identification parameter γ is: Among them, β Rec1 represents the modulation sideband parameter corresponding to the response signal of the low-frequency pump wave, β Rec2 Represents the modulation sideband parameters corresponding to the response signal of the high-frequency detection wave.

8. A computer device, characterized in that: include: A processor and a computer readable storage medium; a processor adapted to execute a computer program; A computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by the processor, the structural defect detection method using mixed-frequency ultrasonic delayed excitation as described in claims 2-5 is implemented.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is suitable for being loaded by a processor and executing the structural defect detection method using mixed-frequency ultrasonic delayed excitation as described in claims 2-5.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the structural defect detection method using mixed-frequency ultrasonic delayed excitation as described in claims 2-5 is implemented.

Images