CN114112921B - A damage detection method, system, medium and equipment based on Ritz transform - Google Patents

Abstract

Compared with the prior art, the damage detection method based on the litz transformation provided by the invention utilizes rich information contained in a guided wave place represented by an analysis signal to reflect damage information. The resolved signals derived from the litz transformation are used to obtain the spatial orientation, phase and amplitude of the reconstructed guided wave field. And spatially deriving the phase from the two coordinates to obtain a spatial wavenumber vector. The magnitude of the spatial wave number vector obtained by the litz transformation represents the spatial wave number value pointing in the propagation direction at each point of the control. The method can be used for relatively complex geometric structures by analyzing the phase information of the signal through the wave field, and evaluating the morphology and the position of the damage by combining the advantages of an algorithm and Lamb waves so as to obtain accurate damage depth information.

Description

A damage detection method, system, medium and equipment based on Ritz transform

technical field

The invention relates to the technical field of structure detection, in particular to a damage detection method based on Ritz transformation.

Background technique

Corrosion is a common damage in civil petrochemical, nuclear industry, and aerospace structures. The presence of corrosion damage can affect the integrity and safety of structures and may lead to catastrophic failure. In terms of aircraft maintenance, the corrosion damage accumulated during the service life of the aircraft is also a potential threat to flight safety. The corrosion damage of the fuselage has always been a direction that needs to be focused on, and more frequent inspections and maintenance are required. It is therefore of great importance to identify, for example, corrosion-type damage that occurs in aircraft structures.

In conventional non-destructive testing methods, ultrasonic testing is often used to detect possible corrosion damage in aircraft, but the couplant used in traditional ultrasonic testing may have an impact on the tested materials. As an emerging non-destructive testing technology, laser ultrasonic testing technology uses laser to excite and receive ultrasonic waves to detect damage in materials and structures. Since no coupling agent is used in the testing process, it is different from traditional ultrasonic testing Compared with the method, it has the characteristics of non-contact. In addition, the pulsed laser beam can be obliquely incident on the surface of the structure in a relatively long distance and within a large angle range for excitation and reception of ultrasonic waves, which is easy to realize automatic detection of complex surface structures. Visualizing and quantifying hidden corrosion through advanced non-destructive assessment is critical to detect corrosion location, quantify corrosion size and depth, ensure structural safety, and reduce lifetime costs.

In addition, detection technology based on Lamb wave (Lamb wave) has been an important technology for detecting, locating and identifying damage in structures for many years. Since the Lamb wave will interact with the damaged part of the material during the propagation process and contain rich information without significant dissipation, it can carry the damage information and propagate a long distance, which is convenient for the detection of large-area specimens. The time-space wave field data in the whole scanning area can be obtained by using the laser to scan in space with a certain step length and receiving the Lamb wave signal. Playing back the guided wave field frame by frame can intuitively see the interaction process between the Lamb wave and the structural features or damage at different times. The damage imaging technology can further analyze the wave field signal to realize the damage detection in the structure. Quantitative detection. In recent years, a variety of damage imaging methods have been developed, but most of the research focuses on the plane location and shape recognition of the damage, such as a Chinese patent with publication number CN109632958A (publication date: April 16, 2019). A Lamb wave damage detection method that considers the crack orientation, while the existing technology has little research on damage depth identification.

To sum up, the quantitative information of the damage in the depth direction is of great significance for damage assessment and subsequent maintenance, and there is a lack of detection and analysis methods for the damage depth direction in the prior art.

Contents of the invention

In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a damage detection method, system, medium and equipment based on Ritz transform, wherein the damage detection method based on Ritz transform includes the following steps:

S10: converting the original wave field signal containing damage information into a frequency domain wave field signal, and selecting a single frequency frequency domain wave field signal corresponding to the main frequency;

S20: Obtain a complex number domain wave field analysis signal corresponding to the single frequency frequency domain wave field signal by performing Ritz transform on the single frequency frequency domain wave field signal;

S30: Obtain the original spatial phase information of the single frequency frequency domain wave field signal by performing phase calculation on the complex number domain wave field analysis signal;

S40: Obtain a real spatial phase by performing phase unwrapping on the original spatial phase information;

S50: Obtain spatial wavenumber information by performing a partial derivative solution in an orthogonal direction on the spatial real phase;

S60: Compare the spatial wavenumber information with the dispersion curve of the corresponding material and frequency, and obtain effective plate thickness information corresponding to the spatial wavenumber information;

S70: Obtain readable information of the damage information through the effective plate thickness information, where the readable information includes damage depth information.

In one embodiment, the step S10 includes the following steps:

S11: The original wave field information includes a space-time wave field signal w(x, y, t), and the frequency domain wave field is obtained by performing a one-dimensional Fourier transform on the space-time wave field signal w(x, y, t) signal w(x,y,f);

S12: Select a single frequency frequency domain wave field signal w(x,y,f 0 ) corresponding to the main frequency f ₀ from the frequency domain wave field signal w(x,y, _f ).

In one embodiment, the step S20 includes: performing Ritz transformation on the single-frequency frequency-domain wave field signal w(x, y, f ₀ ) to obtain the single-frequency frequency-domain wave field signal w(x, y , f ₀ ) corresponding to the component of the complex domain wavefield analysis signal w _m (x, y, t) = [w (x, t, f ₀ ), w _x (x, y, f ₀ ), w _y (x,y,f ₀ )];

The first transform kernel function of the Ritz transform includes

The second transform kernel function of the Ritz transform includes

In one embodiment, the original spatial phase information in the step S30 is defined by the vertex angle defined by the vectorization of the complex domain wavefield analysis signal The local phase representation of , where

In one embodiment, the step S40 includes the following steps:

S41: Construct the reliability matrix R,

in

in,

in Indicates the phase value of the coordinate position, and the function γ(x) is used to obtain the remainder of the variable x and 2π;

S42: Solve the reliability parameters of the boundaries of each coordinate point in the space according to the reliability matrix, where the value of the reliability parameter is the sum of the reliability values of the coordinate points on both sides of the boundary;

S43: Perform phase unwrapping according to the paths from large to small reliability parameters of the boundary of each coordinate point.

In one embodiment, the step S40 further includes after the step S43

Step S44: Perform phase supplementation on the blurred phase in the inverse trigonometric function to obtain the real phase of the space

In one embodiment, the spatial wavenumber information in step S50 includes the modulus of the wavenumber vector of each coordinate point in space;

The wavenumber vector Where k _x , _ky are respectively the real phase of the space/> The partial derivatives in two orthogonal directions, that is, />

The present invention also provides a damage detection system based on Ritz transform, including

A conversion module, through which the original wave field signal containing damage information is converted into a frequency domain wave field signal, and a single frequency frequency domain wave field signal corresponding to the main frequency is selected;

A Ritz transform module, the Ritz transform module is used to perform Ritz transform on the single frequency frequency domain wave field signal to obtain a complex number domain wave field analysis signal corresponding to the single frequency frequency domain wave field signal;

A phase solving module, the phase solving module is used to perform phase solving on the complex number domain wave field analysis signal to obtain the original spatial phase information of the single frequency frequency domain wave field signal;

A phase unwrapping module, the phase unwrapping module is used to perform phase unwrapping on the original spatial phase information to obtain the real spatial phase;

A wavenumber solving module, the wavenumber solving module is used to solve the partial derivative in the orthogonal direction for the real phase of the space to obtain the spatial wavenumber information;

A plate thickness information acquisition module, the plate thickness information acquisition module is used to compare the spatial wavenumber information with the dispersion curve of the corresponding material and frequency, and obtain effective plate thickness information corresponding to the spatial wavenumber information;

A readable information acquisition module, the readable information acquisition module obtains the readable information of the damage information through the effective plate thickness information, and the readable information includes damage depth information.

The present invention also provides a computer-readable storage medium, where computer instructions are stored in the computer-readable storage medium, and when the computer is executed by a processor, the damage detection method based on Ritz transformation as described in any one of the above items is realized.

The present invention also provides a computer device, comprising at least one processor, and a memory communicatively connected to the processor, wherein the memory stores instructions executable by at least one processor, and the instructions are executed by at least one processor , so that the processor executes the Ritz transform-based damage detection method described in any one of the above.

Based on the above, compared with the prior art, the damage detection method based on the Ritz transform provided by the present invention utilizes the rich information contained in the guided wave field represented by the analytical signal to embody the damage information. The analytical signal derived from the Ritz transform is used to obtain the spatial orientation, phase and amplitude of the reconstructed guided wave field. And deriving the phase with respect to the two coordinates in space to obtain the space wavenumber vector. The size of the spatial wavenumber vector obtained through the Ritz transformation represents the spatial wavenumber pointing to the propagation direction at each point of the control. Analyzing the phase information of the signal through the wave field can reflect the information of the small-intensity scattering and reflection wave field, so that the method can be used in more complex geometric structures, combined with the respective advantages of the algorithm and the Lamb wave, to evaluate the shape and position of the damage , to obtain accurate damage depth information.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other beneficial effects of the present invention can be realized and obtained by the structures particularly pointed out in the specification, claims and accompanying drawings.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative work; the positional relationship described in the drawings in the following description, Unless otherwise specified, the orientation of the components shown in the figure is the reference.

Fig. 1 is a schematic flow chart of the damage detection method based on Ritz transform provided by the present invention;

FIG. 2 is a schematic flow diagram of step S10 and step S40 according to an embodiment of the present invention;

Figure 3 Schematic diagram of spatial phase unwrapping;

Fig. 4 is embodiment one plate dispersion curve;

Fig. 5 is the flaw detection waveform diagram of the simulation embodiment;

Fig. 6 is a schematic diagram of the effective plate thickness of the simulation embodiment.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of the embodiments of the present invention, rather than all embodiments; the technical features designed in the different embodiments of the present invention described below can be combined as long as they do not constitute conflicts; based on the embodiments of the present invention, the present invention All other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that all the terms (including technical terms and scientific terms) used in the present invention have the same meanings as commonly understood by those of ordinary skill in the art to which the present invention belongs, and cannot be construed Limitations of the Invention; It should be further understood that the terms used in the present invention should be understood to have a meaning consistent with the meaning of these terms in the context of this specification and in the relevant field, and should not be interpreted in an idealized or overly formal sense , unless explicitly so defined in the present invention.

The following will be described through specific examples.

The present invention provides a kind of damage detection method based on Ritz transformation, with reference to Fig. 1, comprises the following steps:

S10: converting the original wave field signal containing damage information into a frequency domain wave field signal, and selecting a single frequency frequency domain wave field signal corresponding to the main frequency;

S20: Obtain a complex number domain wave field analysis signal corresponding to the single frequency frequency domain wave field signal by performing Ritz transform on the single frequency frequency domain wave field signal;

S30: Obtain the original spatial phase information of the single frequency frequency domain wave field signal by performing phase calculation on the complex number domain wave field analysis signal;

S40: Obtain a real spatial phase by performing phase unwrapping on the original spatial phase information;

S50: Obtain spatial wavenumber information by performing a partial derivative solution in an orthogonal direction on the spatial real phase;

S60: Compare the spatial wavenumber information with the dispersion curve of the corresponding material and frequency, and obtain effective plate thickness information corresponding to the spatial wavenumber information;

S70: Obtain readable information of the damage information through the effective plate thickness information, where the readable information includes damage depth information.

Preferably, the readable information also includes damage orientation and shape information.

Specifically, for example, after obtaining the original signal of the wave field containing damage information through Lamb waves, in order to analyze the depth information of the defect through the time-space domain signal, it needs to go through several main steps of processing. As shown in Figure 2, first step S10 includes the following steps:

S11: The original wave field information includes a space-time wave field signal w(x, y, t), and the frequency domain wave field is obtained by performing a one-dimensional Fourier transform on the space-time wave field signal w(x, y, t) signal w(x,y,f);

S12: Select a single frequency frequency domain wave field signal w(x, y, f 0 ) corresponding to the main frequency f ₀ from the frequency domain wave field signal w(x, y, _f ), preferably, the main frequency f ₀ is the excitation frequency.

Then S20 performs Ritz transformation on the selected single-frequency frequency-domain wave field signal w(x,y,f ₀ ), and constructs an analytical signal R[w(x,y,f ₀ )] corresponding to the single-frequency wave field. For a single-frequency frequency-domain wavefield signal w(x,y,f ₀ ), the first transform kernel function of the Ritz transform in the space-time domain is The second transform kernel function of the Ritz transform includes /> Through the Ritz transform, w(x,y,f ₀ ) can be solved to correspond to the components w _m (x,y,t)=[w(x,y,f ₀ ),w _x ( x,y,f ₀ ), w _y (x,t,f ₀ )].

From the vectorized definition of the analytic signal, we know that the vertex angle Then it represents the local phase, which is the description of the structure information of the image, and the vertex angle defined by the vectorization of the complex number domain wavefield analysis signal/> The local phase of represents the original spatial phase information. Therefore, step S30 solves the original spatial phase information of the single-frequency wave field by the following formula,

Next, in step S40, since the phase is obtained by solving the wave field analysis signal, and the expression of the phase by the complex number is periodic, the range of the phase is between 0 and π when the Ritz transform is used to solve the phase, and the phase is calculated with 2π as the modulo Take the value, there is a 2kπ difference between the real value and the calculated value because of the phase stacking. Obtaining an accurate phase is a key step in realizing detection, so it is necessary to unwrap and restore the phase. The unwrapped phase is shown in Figure 3(a). There are two main problems in unwrapping, the choice of reliability function and the design of phase unwrapping path. In order to choose a reasonable unwrapping path, the reliability function is defined first.

Specifically, steps S41-S43 as shown in FIG. 2 are included. In S41, as shown in the following formula, the phase values of each point are converted into corresponding reliability parameters to form a reliability matrix where D is defined by

Each part of the formula is

in Represents the phase value of the coordinate position, and the function γ(x) is used to obtain the remainder of the variable x and 2π.

Next, in S42, the reliability parameters of the boundary of each coordinate point in the space are calculated according to the reliability matrix, and the value of the reliability parameter is the sum of the reliability values of the coordinate points on both sides of the boundary.

Then in S43, the phase unwrapping is performed according to the path of reliability parameters of the boundary of each coordinate point from large to small.

Preferably, in one embodiment, as shown in FIG. 2, step S40 further includes step S44, performing phase supplementation on the blurred phase in the inverse trigonometric function, so as to obtain the real spatial phase Figure 3(b) is the phase after unwrapping and reduction.

Then, from the perspective of phase, wavenumber can be understood as: the rate of change of phase with distance. Therefore, the partial derivation of the unwrapped phase with respect to the orthogonal direction can obtain the wave number values at each position of the spatial wave field, and then reflect the wave number change characteristics of the guided wave during propagation.

Specifically, the spatial wavenumber information in step S50 includes the modulus of the wavenumber vector of each coordinate point in space;

The wavenumber vector Where k _x , _ky are respectively the real phase of the space/> The partial derivatives in two orthogonal directions, that is, />

Therefore, the spatial wavenumber information

When Lamb waves propagate in plates of different thicknesses and materials, the dispersion curve reveals the relationship between wavenumber and frequency. Since the dispersion curve of Lamb wave is only related to the frequency-thickness product of the material, its frequency-wavenumber correspondence varies with the Therefore, the relationship between the calculated spatial wavenumber and plate thickness can be used to determine the thickness of the corroded residual plate, and then obtain the corrosion depth, so as to realize the quantification of corrosion damage in the depth direction. Taking delamination damage as an example, at the position of the delamination, the subplate (a combination of the plate above the delamination and the plate below the delamination) supports the propagating Lamb wave, and the effective thickness of the detection is the thickness of each subplate . In other words, the effective thickness is the thickness detected by the wave field information. For an original plate without damage, the effective thickness is equivalent to the thickness of the plate; if there is delamination, the effective thickness fed back by the wave field is equal to the delamination interface and the thickness between the scanning interface. Figure 4 shows the dispersion curve of an aluminum plate with a thickness of 2mm. In step S60, the relationship between plate thickness and wave number at different frequencies can be obtained according to the dispersion of plates with different thicknesses.

Preferably, step S70 can reveal the readable information of damage to the board according to the effective thickness information of the board, and the readable information includes damage depth information, orientation and shape information.

The present invention also provides a simulation verification of the above method, which uses abaqus software to simulate the propagation process of the guided wave. The length×width×height dimensions of the simulated aluminum plate are set to be 400mm×400mm×2mm, and the damage form is 20×20mm square corrosion damage. The specific realization is that an area with a size of 20x20mm and a depth of 1mm is set as the disconnection of the finite element node , this defect represents a lack of fusion of the stack in a certain area of the aluminum sheet. The lower left endpoint of the sensing area is set as the coordinate origin, and the sensing area covers the rectangular area that moves from the coordinate origin in the figure to the coordinate (80,80). Set the coordinates of the center point of the corrosion defect to (45,40). The time step of the simulation model is set to 1us, and the grid size is set to 1*1mm. The material properties of the aluminum used for modeling are shown in Table 1, where E is Young's modulus, v is Poisson's ratio, and ρ is the material density. The five-peak signal with 100khz as the main frequency is used for Lamb wave excitation. It can be seen from Figure 5 that the Lamb wave interacts with the damage when it passes through the damage area. Figure 5 shows the image of the damage identified by the algorithm. It can be seen that the wave value in the square damaged area is significantly larger than that in the non-damaged area, and the position and shape of the damage are more accurately displayed. Then display it as an effective thickness display, as shown in Figure 6, it can be recognized that the effective thickness of the damaged area is 1 mm, and the effective thickness of the non-damaged area is 2 mm, which basically coincides with the preset damage depth and plate thickness of the simulation.

Attributes parameter unit E. 70 Gpa v 0.33 ρ 2700 kg·m ^-3

Table 1

The present invention also provides a damage detection system based on Ritz transform, including

A conversion module, through which the original wave field signal containing damage information is converted into a frequency domain wave field signal, and a single frequency frequency domain wave field signal corresponding to the main frequency is selected;

A Ritz transform module, the Ritz transform module is used to perform Ritz transform on the single frequency frequency domain wave field signal to obtain a complex number domain wave field analysis signal corresponding to the single frequency frequency domain wave field signal;

A phase solving module, the phase solving module is used to perform phase solving on the complex number domain wave field analysis signal to obtain the original spatial phase information of the single frequency frequency domain wave field signal;

A phase unwrapping module, the phase unwrapping module is used to perform phase unwrapping on the original spatial phase information to obtain the real spatial phase;

A wavenumber solving module, the wavenumber solving module is used to solve the partial derivative in the orthogonal direction for the real phase of the space to obtain the spatial wavenumber information;

A plate thickness information acquisition module, the plate thickness information acquisition module is used to compare the spatial wavenumber information with the dispersion curve of the corresponding material and frequency, and obtain effective plate thickness information corresponding to the spatial wavenumber information;

A readable information acquisition module, the readable information acquisition module obtains the readable information of the damage information through the effective plate thickness information, and the readable information includes damage depth information.

The present invention also provides a computer-readable storage medium, where computer instructions are stored in the computer-readable storage medium, and when the computer is executed by a processor, the damage detection method based on Ritz transformation as described in any one of the above items is realized.

To sum up, compared with the prior art, the damage detection method based on the Ritz transform provided by the present invention utilizes the rich information contained in the guided wave field represented by the analytical signal to reflect the damage information. The analytical signal derived from the Ritz transform is used to obtain the spatial orientation, phase and amplitude of the reconstructed guided wave field. And deriving the phase with respect to the two coordinates in space to obtain the space wavenumber vector. The size of the spatial wavenumber vector obtained through the Ritz transformation represents the spatial wavenumber pointing to the propagation direction at each point of the control. The phase information of the signal is analyzed by the wave field, which can reflect the information of the small-intensity scattering and reflection wave field, so that the method can be used in more complex geometric structures, combined with the respective advantages of the algorithm and the Lamb wave, to evaluate the shape and position of the damage , to obtain the damage depth information more accurately.

During specific implementation, the computer-readable storage medium is a magnetic disk, an optical disk, a read-only memory (Read-OnlyMemory, ROM), a random access memory (Random Access Memory, RAM), a flash memory (FlashMemory), a hard disk (Hard Disk) Disk Drive, abbreviation: HDD) or solid-state drive (Solid-State Drive, SSD), etc.; the computer-readable storage medium may also include a combination of the above-mentioned types of memory.

The present invention also provides a computer device, comprising at least one processor, and a memory communicatively connected to the processor, wherein the memory stores instructions executable by at least one processor, and the instructions are executed by at least one processor , so that the processor executes the Ritz transform-based damage detection method described in any one of the above.

During specific implementation, the number of processors may be one or more, and the processor may be a central processing unit (Central Processing Unit, CPU). The processor can also be other general-purpose processors, digital signal processors (Digital Signal Processor, DSP), application-specific integrated circuits (Application Specific Integrated Circuit, ASIC), field-programmable gate arrays (Field-Programmable Gate Array, FPGA) or other possible Chips such as programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations of the above types of chips. A general-purpose processor may be a microprocessor, or the processor may be any conventional processor, or the like.

The memory and the processor can be communicated through a bus or other means, and the memory stores instructions that can be executed by at least one processor, and the instructions are executed by at least one processor, so that the processor performs the Ritz transform-based damage detection method.

In addition, those skilled in the art should understand that although there are many problems in the prior art, each embodiment or technical solution of the present invention can only be improved in one or several aspects, and it is not necessary to solve the problems in the prior art or at the same time. All technical problems listed in the background technology. It should be understood by those skilled in the art that anything that is not mentioned in a claim should not be taken as a limitation on the claim.

Although in this paper, such as Ritz transform, single-frequency frequency domain wave field signal, original wave field signal, original spatial phase information, phase unwrapping, spatial real phase, spatial wavenumber information, effective plate thickness information and readable information are widely used. and other terms, but does not exclude the possibility of using other terms. These terms are only used to describe and explain the essence of the present invention more conveniently; interpreting them as any kind of additional limitation is against the spirit of the present invention; The terms "first", "second", etc. in the drawings, if present, are used to distinguish similar items and are not necessarily used to describe a specific order or sequence.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (10)

1. The damage detection method based on the litz transformation is characterized by comprising the following steps of:

s10: obtaining an original wave field signal containing damage information through a Lamb wave signal on an acquisition board, wherein the original wave field signal contains a time-space domain signal, converting the time-space domain signal in the original wave field signal into a frequency domain wave field signal, and selecting a Shan Pinpin domain wave field signal corresponding to a main frequency;

s20: obtaining a complex domain wave field analysis signal corresponding to the Shan Pinpin domain wave field signal by performing litz transformation on the Shan Pinpin domain wave field signal;

s30: obtaining original spatial phase information of the Shan Pinpin domain wave field signal by performing a phase solution on the complex domain wave field analytic signal;

s40: the original spatial phase information is subjected to phase unwrapping to obtain a real spatial phase;

s50: obtaining space wave number information by carrying out bias derivative solution in the orthogonal direction on the real space phase;

s60: comparing the space wave number information with a dispersion curve of a corresponding material and frequency to obtain effective plate thickness information corresponding to the space wave number information;

s70: and obtaining readable information of the damage information according to the effective plate thickness information, wherein the readable information comprises damage depth information.

2. The litz transformation-based impairment detection method of claim 1, wherein: the step S10 comprises the following steps:

s11: the raw wave field information comprises a space-time wave field signalBy applying to the space-time wave field signalPerforming one-dimensional Fourier transform to obtain the frequency domain wave field signal +.>;

S12: from the frequency domain wave field signalThe main frequency is selected out>Corresponding Shan Pinpin domain wave field signal。

3. The litz transformation-based impairment detection method of claim 2, wherein: the step S20 includes: for the Shan Pinpin domain wave field signalSolving the Shan Pinpin domain wave field signal by performing a litz transformationConstituent parts of the corresponding complex domain wavefield resolution signal；

The first transformation kernel of the litz transformation comprises;

The second transformation kernel of the litz transformation comprises。

4. The litz transformation-based impairment detection method of claim 3, wherein: the original spatial phase information in the step S30 is defined by vectorization of the complex domain wave field analysis signal to define a vertex angleIn which

。

5. The litz transformation-based impairment detection method of claim 1, wherein: the step S40 includes the steps of:

s41: constructing a reliability matrix，

，

wherein ；

wherein ,

；

；

；

；

wherein Phase value representing the coordinate position, function->For determining the variable->And->Remainder of (2);

s41: solving reliability parameters of boundaries of coordinate points of a space according to the reliability matrix, wherein the value of the reliability parameters is the sum of reliability values of the coordinate points at two sides of the boundary;

s43: and performing phase unwrapping according to paths from large to small of the reliability parameters of the boundaries of the coordinate points.

6. The litz transformation-based impairment detection method of claim 5, wherein: the step S40 further comprises, after the step S43

Step S44: phase supplementing the blurred phase in the inverse trigonometric function to obtain the real phase in space。

7. The litz transformation-based impairment detection method of claim 6, wherein: the spatial wave number information in the step S50 includes a modulus value of a wave number vector of each coordinate point in space;

the wave number vector, wherein />Respectively the spatial true phases +.>Deviation from two orthogonal directions, i.e. +.>，/>。

8. A litz transformation-based damage detection system, characterized by: comprising

The conversion module is used for obtaining an original wave field signal containing damage information through Lamb wave signals on the acquisition board, the original wave field signal contains time-space domain signals, converting the time-space domain signals in the original wave field signal into frequency domain wave field signals through the conversion module, and selecting Shan Pinpin domain wave field signals corresponding to main frequencies;

the litz transformation module is used for carrying out litz transformation on the Shan Pinpin domain wave field signal so as to obtain a complex domain wave field analysis signal corresponding to the Shan Pinpin domain wave field signal;

the phase solving module is used for carrying out phase solving on the complex domain wave field analysis signals to obtain original spatial phase information of the Shan Pinpin domain wave field signals;

the phase unwrapping module is used for unwrapping the phase of the original spatial phase information to obtain a real spatial phase;

the wave number solving module is used for carrying out bias guide solving in the orthogonal direction on the real space phase to obtain space wave number information;

the plate thickness information acquisition module is used for comparing the space wave number information with a dispersion curve of a corresponding material and frequency to acquire effective plate thickness information corresponding to the space wave number information;

and the readable information acquisition module obtains readable information of the damage information through the effective plate thickness information, wherein the readable information comprises damage depth information.

9. A computer-readable storage medium, characterized by: the computer readable storage medium stores computer instructions which, when executed by a processor, implement the litz transformation based impairment detection method according to any one of claims 1-7.

10. A computer device, characterized by: comprising at least one processor, and a memory communicatively coupled to the processor, wherein the memory stores instructions executable by the at least one processor to cause the processor to perform the litz transformation-based impairment detection method according to any one of claims 1-7.