A composite defect signal quantization detection method

Abstract

The application discloses a composite defect signal quantification detection method, relates to the technical field of industrial nondestructive testing, and is characterized in that: a defect space leakage magnetic field is established, a three-dimensional rectangular coordinate system is established based on a magnetic charge model, magnetic charge density corresponding to a magnetic charge unit segmented on a defect end face is established, the relationship between a ferromagnetic material and stress is determined, magnetic induction intensity and unit area corresponding to the magnetic charge unit segmented on the defect end face are established, total magnetic charge density, magnetic induction intensity and area of the defect end face are established, and then axial and radial components of a defect magnetic signal are solved. The application fully considers the influence of stress on defects of the ferromagnetic material, simulates and calculates signal characteristics of the magnetic signal of the ferromagnetic material under the action of different defect stresses, and provides a more comprehensive, efficient and stable detection method for defect evaluation of the ferromagnetic component by the leakage magnetic detection technology.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial nondestructive testing, in particular to a detection method for signal quantification of composite defects. BACKGROUND

[0002] Ferromagnetic materials may have potential safety hazards such as cracks, corrosion, and stress damage in long-term engineering service due to adverse environmental factors and improper human operation. Once a sudden dangerous accident such as leakage or explosion occurs, it will not only cause environmental pollution and energy loss, but also seriously threaten the safety of the people. Therefore, it is of great economic and social significance to ensure the safe operation of ferromagnetic materials. The current mainstream magnetic flux leakage detection technology uses a uniform magnetic charge model as the theoretical basis to calculate the magnetic signals of different defect sizes. However, the magnetic dipoles inside the magnetic charge are affected by the Coulomb force, and the corresponding magnetic charge distribution at the defect side wall is not ideal uniform distribution, resulting in a large error between the analytical value and the experimental measurement value. In addition, the existing magnetic flux leakage detection technology does not consider the influence of stress on the magnetic signal. The stress at the defect is much higher than the average stress of the material, and it is impossible to avoid sudden accidents caused by stress damage. The existing methods cannot accurately identify composite defects, affecting the quantification accuracy and detection efficiency. SUMMARY

[0003] OBJECTIVE

[0004] The present application provides a composite defect signal quantification detection method, which aims to solve the problem that in the prior art, due to the influence of the magnetic dipoles inside the magnetic charge on the Coulomb force, the corresponding magnetic charge distribution at the defect side wall is not ideal uniform distribution, and in addition, the stress at the defect is much higher than the average stress of the material, it is difficult to find the quantitative relationship between stress and magnetic signal in the prior art, resulting in a large error between the analytical value and the experimental measurement value, and the problem that accurate identification of composite defects cannot be achieved.

[0005] TECHNICAL SCHEME

[0006] A composite defect signal quantification detection method, characterized in that the detection method is carried out according to the following steps:

[0007] (1) Based on the magnetic charge model, a three-dimensional rectangular coordinate system of the defect space magnetic leakage field is established with the center of the defect as the origin, and the magnetic field intensity at any point in the defect space field is obtained;

[0008] (2) The rectangular defect magnetic charge surface is divided into a plurality of magnetic charge units, and the magnetic charge density corresponding to the magnetic charge unit at any position on the defect end surface is obtained;

[0009] (3) Considering the influence of stress on the magnetic signal at the defect end surface, the relationship between the relative magnetic permeability of the ferromagnetic material and the stress is determined;

[0010] (4) By establishing the magnetic induction intensity and unit area corresponding to the magnetic charge unit segmented by the defect end face, the key physical quantity magnetic induction intensity, which is used to quantitatively describe the characteristics of each point in the magnetic field, is obtained.

[0011] (5) The magnetic induction intensity and unit area corresponding to each magnetic charge unit on the defect sidewall are accumulated by matrix method to obtain the total magnetic induction intensity and total area at the defect end face;

[0012] (6) The total magnetic charge density at the defect end face is obtained by the correspondence between the total magnetic charge density, total magnetic induction intensity and total area at the defect end face and by a series of transformations.

[0013] (7) Based on the calculation results of the non-uniform magnetic charge density at the defect end face, the magnetic field at the defect end face is integrated in two variables to obtain the axial signal component and radial signal component of the defect leakage magnetic field.

[0014] The method established based on the above steps makes the magnetic charge distribution on the defect sidewall more closely resemble the magnetic charge distribution on the defect sidewall of ferromagnetic materials under actual working conditions.

[0015] Establishing the leakage magnetic field in the defect space: Based on the magnetic charge model, a three-dimensional rectangular coordinate system is established; let the rectangular defect magnetic charge surface element on the end face be dy. n dz n The magnetic field strength generated at any point P(x, y, z) in the spatial field can be expressed as:

[0016]

[0017] Where: ρ is the magnetic charge density formed on the defect end face, and μ0 is the free magnetic permeability. It is a unit direction vector;

[0018] Establish the magnetic charge density corresponding to the magnetic charge element segmented by the defect end face: Divide the rectangular defect magnetic charge surface into several magnetic charge elements, with the defect center as the origin, and let the axial direction of the rectangular groove defect be the X-axis, the radial direction be the Y-axis, and the circumferential direction be the Z-axis; then, the magnetic charge density corresponding to the magnetic charge element at any position on the defect end face can be expressed as:

[0019]

[0020] Among them: 2D x 2D z D y These represent the axial length, circumferential width, and radial depth of the rectangular groove, respectively. μ r K represents the relative permeability of the dielectric material; K = D x, i, j represent the number of rows and columns of the partition, (K, i, j) coordinates represent the position of the magnetic charge unit in the defect space region;

[0021] The relationship between the ferromagnetic material and the stress can be expressed as:

[0022]

[0023] Where: σ is the stress, Man is the anhysteretic magnetization, Ms is the saturation magnetization, He is the effective magnetic field, α is the magnetic domain coupling coefficient, a is the material planning constant, and ξ is the unit volume energy measurement factor;

[0024] The magnetic induction intensity and the unit area corresponding to the magnetic charge unit of the partitioned defect end face are established: the magnetic induction intensity B is a key physical quantity for quantitatively describing the characteristics of each point in the magnetic field, and the magnetic induction intensity corresponding to the magnetic charge unit at any position can be expressed as:

[0025] B K,i,j = 4π * ρ(K, i, j) * S(K, i, j) (4)

[0026] Where: S(K, i, j) represents the area of the magnetic charge unit at the position coordinates of the defect end face;

[0027] S is extended as follows, as follows:

[0028]

[0029] The total magnetic charge density, the magnetic induction intensity and the area of the defect end face are established: the magnetic charge density, the magnetic induction intensity and the unit area corresponding to each magnetic charge unit of the defect side wall are accumulated through the matrix method, and the total magnetic charge density, the total magnetic induction intensity and the total area at the defect end face are obtained, which can be expressed as the following formula:

[0030]

[0031]

[0032]

[0033] Solving the total magnetic charge density of the defect end face: formula (6), (7) and (8) are converted into the form of matrix multiplication:

[0034]

[0035] Through the matrix transformation rule, formula (9) is further converted to obtain the total magnetic charge density ρ total of the defect end face:

[0036]

[0037] Solving the axial component and radial component of the defect magnetic signal: the rectangular side wall defect range is from -Dy to 0 in the Y-axis direction, and from -Dz to Dz in the Z-axis direction, and the binary integral of the defect end face magnetic field H is carried out to obtain the axial signal component Hx and the radial signal component Hy of the defect magnetic field respectively;

[0038]

[0039]

[0040] Advantages and effects:

[0041] The application is based on the magnetic charge theory, and a mathematical analysis model of composite defect magnetic signal is established. The signal characteristics of the magnetic signal of the ferromagnetic material under the action of different defect sizes and stresses are simulated, and the corresponding relationship between the magnetic signal and the different defect sizes and stresses is calculated, so that a high-efficiency and stable detection method for the life evaluation of the ferromagnetic component by the magnetic flux leakage detection technology is provided. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The magnetic flux leakage detection technology provided by the application is a working schematic diagram;

[0043] Figure 2 The defect magnetic charge distribution provided by the application is a schematic diagram;

[0044] Figure 3 The signal distribution diagram corresponding to different defect depth sizes provided by the application is a schematic diagram;

[0045] Figure 4 The signal change diagram corresponding to different defect depth sizes provided by the application is a schematic diagram;

[0046] Figure 5 The signal distribution diagram corresponding to different defect width sizes provided by the application is a schematic diagram;

[0047] Figure 6 The signal change diagram corresponding to different defect width sizes provided by the application is a schematic diagram;

[0048] Figure 7 The signal distribution diagram corresponding to different defect stress provided by the application is a schematic diagram;

[0049] Figure 8 The signal change diagram corresponding to different defect stress provided by the application is a schematic diagram;

[0050] Figure 9 The axial signal data acquisition diagram of the experimental sample 1 of the application is a schematic diagram;

[0051] Figure 10 The radial signal data acquisition diagram of the experimental sample 1 of the application is a schematic diagram;

[0052] Figure 11 The stress-magnetic signal curve of the experimental sample 2 of the present application. DETAILED DESCRIPTION

[0053] The purpose of the present application is to provide a ferromagnetic material composite defect signal quantitative detection method, which can effectively solve the problem of large error between analytical calculation value and experimental measurement value, realize precise quantization of magnetic signals under the action of different defect sizes and stress, and improve detection precision and detection quality.

[0054] The detection method is carried out according to the following steps:

[0055] (1) Based on the magnetic charge model, a three-dimensional rectangular coordinate system of the defect space leakage magnetic field is established with the center of the defect as the origin, and the magnetic field intensity at any point in the defect space field is obtained;

[0056] (2) The rectangular defect magnetic charge surface is divided into a plurality of magnetic charge units, and the magnetic charge density corresponding to the magnetic charge unit at any position on the defect end surface is obtained;

[0057] (3) Considering the influence of stress on the magnetic signal at the defect end surface, the relationship between the relative magnetic permeability of the ferromagnetic material and the stress is determined;

[0058] (4) By establishing the magnetic induction intensity and unit area corresponding to the magnetic charge unit divided on the defect end surface, the magnetic induction intensity is obtained as a key physical quantity for quantitatively describing the characteristics of each point in the magnetic field;

[0059] (5) The magnetic induction intensity and unit area corresponding to each magnetic charge unit of the defect side wall are accumulated in the form of a matrix to obtain the total magnetic induction intensity and total area at the defect end surface;

[0060] (6) Through the corresponding relationship between the total magnetic charge density, the total magnetic induction intensity and the total area at the defect end surface, and a series of conversions, the total magnetic charge density corresponding to the defect end surface is obtained;

[0061] (7) Based on the non-uniform magnetic charge density calculation result at the defect end surface, the binary integration of the magnetic field at the defect end surface is carried out to obtain the axial signal component and the radial signal component of the defect leakage magnetic field;

[0062] The method established according to the above steps makes the magnetic charge distribution of the defect side wall closer to the actual working condition environment of the ferromagnetic material defect side wall.

[0063] Establish the defect space leakage magnetic field: based on the magnetic charge model, a three-dimensional rectangular coordinate system is established; the rectangular defect magnetic charge surface element on the end surface is dy n , dz n , and an arbitrary point P(x, y, z) in the space field is selected, and the magnetic field intensity generated at the point can be expressed as:

[0064]

[0065] wherein: p is the magnetic charge density formed on the defect end face, μ0 is the vacuum permeability, is the unit direction vector;

[0066] The magnetic charge density corresponding to the magnetic charge unit of the segmented defect end face is established: the rectangular defect magnetic charge surface is segmented into several magnetic charge units, taking the defect center as the origin, and the axial direction of the rectangular groove defect is X axis, the radial direction is Y axis, and the circumferential direction is Z axis; At this time, the magnetic charge density corresponding to the magnetic charge unit at any position of the defect end face can be expressed as:

[0067]

[0068] wherein: 2D x , 2D z , D y respectively represent the axial length, circumferential width and radial depth of the rectangular groove. μ r is the relative permeability of the dielectric material; K=D x , i, j represent the number of rows and columns of segmentation, and (K, i, j) coordinates represent the position of the magnetic charge unit in the defect space region;

[0069] The relationship between the relative permeability of the ferromagnetic material and the stress can be expressed as:

[0070]

[0071] wherein: σ is the stress, Man is the anhysteretic magnetization, Ms is the saturation magnetization, He is the effective magnetic field, α is the magnetic domain coupling coefficient, a is the material planning constant, and ξ is the unit volume energy measurement factor;

[0072] The magnetic induction intensity and unit area corresponding to the magnetic charge unit of the segmented defect end face are established: the magnetic induction intensity B is the key physical quantity for quantitatively describing the characteristics of each point in the magnetic field, and the magnetic induction intensity corresponding to the magnetic charge unit at any position can be expressed as:

[0073] B K,i,j =4π*ρ(K,i,j)*S(K,i,j) (4)

[0074] wherein: S(K, i, j) represents the area of the magnetic charge unit at the position coordinates of the defect end face;

[0075] S is extended as follows, as follows:

[0076]

[0077] The total magnetic charge density, magnetic induction intensity and area of the defect end face are established by accumulating the magnetic charge density, magnetic induction intensity and unit area corresponding to each magnetic charge unit of the defect side wall through a matrix to obtain the total magnetic charge density, total magnetic induction intensity and total area of the defect end face, which can be expressed as the following formula:

[0078]

[0079]

[0080]

[0081] Solving the total magnetic charge density of the defect end face: formula (6), (7) and (8) are converted into the form of matrix multiplication:

[0082]

[0083] By matrix transformation rule, formula (9) is further converted to obtain the total magnetic charge density of the defect end face total :

[0084]

[0085] Solving the axial component and radial component of the defect magnetic signal: the range of the rectangular side wall defect is from -Dy to 0 in the Y axis direction and from -Dz to Dz in the Z axis direction, and the binary integration of the defect end face magnetic field H is carried out to obtain the axial signal component Hx and the radial signal component Hy of the defect magnetic field, respectively.

[0086]

[0087]

[0088] Through the above method, the non-uniform distribution of the magnetic charge of the defect end face is established to establish a spatial magnetic leakage field detection mathematical analysis model, so that the magnetic signal result of the ferromagnetic material calculated by analysis is more accurate, the quantitative error is reduced, the detection efficiency is improved, and the accurate interpretation of the defect of the ferromagnetic material is realized.

[0089] The present application fully considers the influence of stress on the defect of the ferromagnetic material, simulates and calculates the signal characteristics of the magnetic signal of the ferromagnetic material under the action of different defect stresses, and provides a more comprehensive, efficient and stable detection method for the defect evaluation of the ferromagnetic component by the magnetic leakage detection technology.

[0090] The following drawings will be described in detail:

[0091] Figure 1The schematic diagram of the magnetic flux leakage detection technology provided by the application. The schematic diagram comprises a pipeline 1, a magnetic force line 2, an odometer wheel 3, a fixed support 4, a leather bowl 5, a universal joint 6, a steel brush 7, a probe 8, a magnetic flux leakage field 9 and a defect 10. The magnetic flux leakage inner detector is composed of the odometer wheel 3, the fixed support 4, the leather bowl 5, the universal joint 6, the steel brush 7 and the probe 8.

[0092] When the oil and gas pipeline is magnetized by external excitation, if the pipeline to be detected has defects, the defects are mainly filled with air, oil and other impurities, compared with ferromagnetic materials, the magnetic permeability of the defects is smaller, the magnetic resistance is larger, the magnetic force line will bypass the low magnetic permeability defects, and there will be magnetic force line leakage on both sides of the defects along the magnetization direction, thereby generating a defect magnetic flux leakage field. At this time, the three-dimensional ultra-high-definition probe in the pipeline magnetic flux leakage inner detector will collect and store the defect signal and then analyze it to evaluate the pipeline defect damage. The above whole process is the working principle of the pipeline magnetic flux leakage inner detection technology.

[0093] Figure 2 The defect magnetic charge distribution schematic diagram provided by the application. The schematic diagram comprises a positive magnetic charge 11, a defect 12, a pipe body 13, a negative magnetic charge 14 and a defect sidewall magnetic charge distribution 15.

[0094] In the actual detection process, the pipe body is magnetized by the outside world to reach the magnetic saturation state, and the internal magnetic dipole of the magnetic charge is excited. Due to the influence of the coulomb force, the magnetic charge originally in a stable state at the defect sidewall will be offset, and the distribution of the stable magnetic charge corresponding to the defect sidewall is not ideal uniform distribution.

[0095] Figure 3 The signal distribution diagram corresponding to different defect depth sizes provided by the application. The distribution diagram comprises a defect magnetic flux leakage signal axial component distribution (a) diagram and a defect magnetic flux leakage signal radial component distribution (b) diagram.

[0096] The defect size axial length is 10mm, the circumferential width is 10mm, the radial depth varies in the range of 2-7mm with an increment of 1mm. The external magnetic field excitation strength is 15,000A / m, and the detector lift-off value is 2mm. When other conditions are constant, with the increase of the defect depth, the corresponding magnetic flux leakage signal component increases, and the waveform changes are consistent. The axial signal component appears a single wave peak and is distributed in an axial symmetry state, and the radial signal component appears a wave peak and a wave trough and is distributed in a sinusoidal fluctuation state.

[0097] Figure 4 The signal change diagram corresponding to different defect depth sizes provided by the application. The distribution diagram comprises a defect axial peak signal component change (a) diagram and a defect radial peak-peak signal component change (b) diagram.

[0098] When other conditions are constant, with the increase of defect depth, the defect side wall magnetic charge accumulation area increases, the axial signal characteristic value component and the radial signal characteristic value component increase nonlinearly, and the change trend conforms to the first-order exponential function change.

[0099] Figure 5 The application provides a signal distribution diagram corresponding to different defect widths.

[0100] The defect size axial length is 15 mm, the radial depth is 5 mm, the circumferential width changes in the range of 5-10 mm, and the increment is 1 mm. The external magnetic field excitation strength is 15,000 A / m, and the detector lift-off value is 2 mm. When other conditions are constant, with the increase of defect width, the defect side wall magnetic charge accumulation area increases, and the corresponding magnetic flux leakage signal component increases, and the waveform changes uniformly. The axial signal component appears extreme value, and is accompanied by double peaks on the left and right, and is distributed in an axial symmetry state, and the radial signal component appears wave peak and wave trough, and is distributed in a sinusoidal fluctuation state.

[0101] Figure 6 The application provides a signal change diagram corresponding to different defect depths.

[0102] When other conditions are constant, with the increase of defect width, the defect side wall magnetic charge accumulation area increases, the axial signal characteristic value component and the radial signal characteristic value component increase nonlinearly, and the change trend conforms to the first-order exponential function change.

[0103] Figure 7 The application provides a signal distribution diagram corresponding to different defect stresses.

[0104] The defect size axial length is 5 mm, the radial depth is 5 mm, the circumferential width changes in the range of 10 mm, the stress changes in the range of 0-3 Mpa, and the increment is 0.5 Mpa. The external magnetic field excitation strength is 15,000 A / m, and the detector lift-off value is 2 mm. When other conditions are constant, with the increase of defect stress, the corresponding magnetic flux leakage signal component decreases, and the waveform changes uniformly. The axial signal component exists single peak, and is distributed in an axial symmetry state, and the radial signal component appears wave peak and wave trough, and is distributed in a sinusoidal fluctuation state.

[0105] Figure 8 The application provides a signal change diagram corresponding to different defect stresses.

[0106] Under other conditions constant, with the increase of defect stress, the relative permeability of the ferromagnetic material decreases, the axial signal eigenvalue component and the radial signal eigenvalue component nonlinearly decrease, and the change trend conforms to the first-order exponential function change.

[0107] Figure 9 Fig. 1 is an axial signal data collection diagram of experimental sample 1 of the present application. The experimental data collection diagram is an axial signal data collection diagram of X70 steel test pieces of experimental sample 1 with different defect sizes. The diagram includes axial signal data collection diagrams of the test pieces with defect depths of (0.64, 1.21, 2.45, 4.63) in sequence. Figures 1-4 Fig. 2 is a radial signal data collection diagram of experimental sample 1 of the present application. The experimental data collection diagram is a radial signal data collection diagram of X70 steel test pieces of experimental sample 1 with different defect sizes. The diagram includes radial signal data collection diagrams of the test pieces with defect depths of (0.64, 1.21, 2.45, 4.63) in sequence. Figures 5-8 .

[0108] Figure 10 Fig. 1 is an axial signal data collection diagram of experimental sample 1 of the present application. The experimental data collection diagram is an axial signal data collection diagram of X70 steel test pieces of experimental sample 1 with different defect sizes. The diagram includes axial signal data collection diagrams of the test pieces with defect depths of (0.64, 1.21, 2.45, 4.63) in sequence. Figures 1-4 Fig. 2 is a radial signal data collection diagram of experimental sample 1 of the present application. The experimental data collection diagram is a radial signal data collection diagram of X70 steel test pieces of experimental sample 1 with different defect sizes. The diagram includes radial signal data collection diagrams of the test pieces with defect depths of (0.64, 1.21, 2.45, 4.63) in sequence. Figures 5-8 .

[0109] Figure 11 Fig. 1 is an axial signal data collection diagram of experimental sample 1 of the present application. The experimental data collection diagram is an axial signal data collection diagram of X70 steel test pieces of experimental sample 1 with different defect sizes. The diagram includes axial signal data collection diagrams of the test pieces with defect depths of (0.64, 1.21, 2.45, 4.63) in sequence.

[0110] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0111] The principles and implementation manners of the present application are described by using specific examples in the present application. The above embodiment description is only used to help understand the method and core idea of the present application; meanwhile, according to the idea of the present application, the specific implementation manner and application range can be changed by the person skilled in the art.

Claims

1. A method for quantitative detection of composite defect signals, characterized in that: The detection method is performed according to the following steps: (1) Based on the magnetic charge model, a three-dimensional rectangular coordinate system of the leakage magnetic field in the defect space is established with the defect center as the origin, so as to obtain the magnetic field strength at any point in the defect space field; (2) Divide the rectangular defect magnetic charge surface into several magnetic charge units to obtain the magnetic charge density corresponding to the magnetic charge unit at any position on the defect end face; (3) Considering the influence of stress on the magnetic signal at the defect end face, determine the relationship between the relative permeability of the ferromagnetic material and the stress; (4) By establishing the magnetic induction intensity and unit area corresponding to the magnetic charge unit segmented by the defect end face, the key physical quantity magnetic induction intensity, which is used to quantitatively describe the characteristics of each point in the magnetic field, is obtained. (5) The magnetic induction intensity and unit area corresponding to each magnetic charge unit on the defect sidewall are accumulated by matrix method to obtain the total magnetic induction intensity and total area at the defect end face; (6) The total magnetic charge density at the defect end face is obtained by the correspondence between the total magnetic charge density, total magnetic induction intensity and total area at the defect end face and by performing a series of transformations. (7) Based on the calculation results of the non-uniform magnetic charge density at the defect end face, the magnetic field at the defect end face is integrated in two variables to obtain the axial signal component and radial signal component of the defect leakage magnetic field. The method established based on the above steps makes the magnetic charge distribution on the defect sidewall more closely resemble the magnetic charge distribution on the defect sidewall of ferromagnetic materials under actual working conditions.

2. The method for quantifying and detecting composite defect signals according to claim 1, characterized in that: Step (1) Establish the leakage magnetic field in the defect space: Based on the magnetic charge model, establish a three-dimensional rectangular coordinate system; let the rectangular defect magnetic charge surface element on the end face be d. y n d z n Choose any point P in the spatial field. x, y, z The magnetic field strength generated at that point can be expressed as: (1) in: The magnetic charge density formed on the defect end face. The permeability of free space, It is a unit direction vector.

3. The method for quantifying and detecting composite defect signals according to claim 1, characterized in that: Step (2) Establish the magnetic charge density corresponding to the magnetic charge unit segmented by the defect end face: Divide the rectangular defect magnetic charge surface into several magnetic charge units, with the defect center as the origin, and set the axial direction of the rectangular groove defect as... X The axis, radial direction is Y Axis, circumferential direction is Z Axis; at this time, the magnetic charge density corresponding to the magnetic charge element at any position on the defect end face can be expressed as: （2） Among them: 2 D x ,2 D z , D y These represent the axial length, circumferential width, and radial depth of the rectangular groove, respectively. μ r The relative permeability of the dielectric material; K = D x , i , j Represents the number of rows and columns in the partition, ( K, i, j The coordinates represent the positions of the magnetic charge elements within the defect space region.

4. The method for quantifying and detecting composite defect signals according to claim 1, characterized in that: Step (3) determines that the relationship between the relative permeability of a ferromagnetic material and stress can be expressed as: (3) Where: σ is stress, Man is hysteresis-free magnetization, Ms is saturation magnetization, and He is the effective magnetic field. denoted as the magnetic domain coupling coefficient, and α as the material planning constant. This is the energy metric per unit volume.

5. The method for quantifying and detecting composite defect signals according to claim 1, characterized in that: Step (4) Establish the magnetic induction intensity and unit area corresponding to the magnetic charge unit segmented by the defect end face: The magnetic induction intensity B, as a key physical quantity for quantitatively describing the characteristics of each point in the magnetic field, can be expressed as the magnetic induction intensity corresponding to the magnetic charge unit at any position as follows: （4） Where: S(K, i, j) represents the area of ​​the magnetic charge unit at the position coordinates of the defect end face; S is extended as follows: （5）。 6. The method for quantifying and detecting composite defect signals according to claim 5, characterized in that: Step (5) Establish the total magnetic charge density, magnetic induction intensity, and area of ​​the defect end face: The magnetic charge density, magnetic induction intensity, and unit area corresponding to each magnetic charge unit on the defect sidewall are accumulated in a matrix manner to obtain the total magnetic charge density, total magnetic induction intensity, and total area at the defect end face, which can be expressed as the following formula: （6） （7） （8）。 7. The method for quantifying and detecting composite defect signals according to claim 6, characterized in that: Step (6) Solve for the total magnetic charge density at the defect end face: Transform equations (6), (7), and (8) into a matrix product: （9） By using the matrix transformation rule, equation (9) is further transformed to obtain the total magnetic charge density corresponding to the defect end face. : （10）。 8. The method for quantifying and detecting composite defect signals according to claim 1, characterized in that: Step (7) Solve for the axial and radial components of the defect magnetic signal: The rectangular sidewall defect ranges from -Dy to 0 in the Y-axis direction and from -Dz to Dz in the Z-axis direction. Perform a binary integration on the magnetic field H at the defect end face to obtain the axial signal component Hx and the radial signal component Hy of the defect leakage magnetic field. (11) (12)。

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