Longitudinal and transverse wave electromagnetic ultrasonic transducer and magnetic induction intensity calculation method

Abstract

The invention relates to the technical field of electromagnetic wave generation devices, in particular to a longitudinal and transverse wave electromagnetic ultrasonic transducer and a magnetic induction intensity calculation method. According to the longitudinal and transverse wave electromagnetic ultrasonic transducer, the unique five-layer sandwich structure permanent magnet layout is adopted, namely, the first permanent magnet is matched with the symmetrical second permanent magnets on the two sides and the third permanent magnet on the outer side, the magnetic pole directions of the different permanent magnets are arranged according to a specific rule, and meanwhile the longitudinal wave coil and the transverse wave coil are matched; therefore, the transducer can generate different Lorentz forces along the vertical direction and the horizontal direction so as to generate a plurality of different modal signals. The method has the advantages that the method can adapt to complex and changeable detection working conditions, meets diversified detection requirements, provides a more flexible and comprehensive solution for detection work, and effectively improves the accuracy and reliability of detection.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic wave generating devices, in particular to a longitudinal and transverse wave electromagnetic ultrasonic transducer and a method for calculating magnetic induction intensity. Background Art

[0002] In the field of non-destructive testing, ultrasonic testing technology is rich and varied, and its application scenarios are wide. Currently, the excitation and reception of body waves are mostly generated by traditional piezoelectric ultrasound, but piezoelectric ultrasound technology requires coupling agent and surface polishing pretreatment, which makes it difficult to apply to high-temperature detection.

[0003] Therefore, in order to solve the above problems, researchers have designed many new electromagnetic ultrasonic transducers. Patent CN114441641B discloses a longitudinal wave electromagnetic ultrasonic probe, which consists of a plurality of rectangular magnet groups with the same magnetic poles arranged face to face, an excitation and detection signal coil, a signal connection line and a probe housing for fixing the magnet group. The coil is fixed under the magnet of the rectangular magnet group, the coil conductor part is located directly under the magnet, and the coil gap is directly opposite to the magnet gap. The electromagnetic ultrasonic probe is directly close to the surface of the test piece to be tested, and the magnetic lines of force are emitted from the N poles of the two magnets arranged face to face, pass through the gap and return to the S poles of the two adjacent magnets, forming a high-intensity horizontal bias magnetic field arranged alternately left and right directly under the magnet. The coil is passed through a radio frequency pulse current, and the eddy current arranged alternately front and back is induced near the surface of the test piece to be tested, and interacts with the horizontal magnetic field to form a Lorentz force perpendicular to the surface of the test piece and in the same direction, thereby realizing efficient excitation and reception of ultrasonic longitudinal waves in the test piece.

[0004] Compared with traditional piezoelectric ultrasound, the electromagnetic ultrasonic transducer composed of the above-mentioned probe in the prior art has the advantages of no need for coupling agent and non-contact, and is suitable for high-temperature scenes. However, its disadvantages are also obvious, that is, the electromagnetic ultrasonic transducer can only generate one modal signal, which is difficult to meet the detection needs under complex working conditions, so it needs to be solved urgently. Summary of the invention

[0005] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a longitudinal and transverse wave electromagnetic ultrasonic transducer and a method for calculating magnetic induction intensity. The electromagnetic ultrasonic transducer of the present invention can generate a variety of different modal signals to be applicable to a variety of complex detection conditions.

[0006] To achieve the above object, the present invention provides the following technical solutions: A longitudinal and transverse wave electromagnetic ultrasonic transducer comprises a first permanent magnet and two second permanent magnets symmetrically arranged on both sides of the first permanent magnet, a third permanent magnet is arranged on the outer side of each of the two second permanent magnets to cooperate to form a five-layer sandwich structure; the magnetic pole directions of the first permanent magnet and the two third permanent magnets are arranged in the horizontal direction, and the magnetic pole directions of the two third permanent magnets are opposite to the magnetic pole directions of the first permanent magnet; the magnetic pole directions of the two second permanent magnets are arranged in the vertical direction, and the magnetic pole directions of the two second permanent magnets are opposite to each other; a longitudinal wave coil is arranged below the first permanent magnet, and the longitudinal wave coil cooperates with the first permanent magnet to generate a first Lorentz force acting on a test piece to be tested in the vertical direction; and a transverse wave coil is arranged below the two second permanent magnets, and the transverse wave coil cooperates with the second permanent magnet to generate a second Lorentz force acting horizontally on the test piece to be tested.

[0007] As a further solution of the present invention: the magnetic pole direction of the first permanent magnet is horizontal to the left, the magnetic pole direction of the second permanent magnet located on the right side of the first permanent magnet is vertically upward, the magnetic pole direction of the second permanent magnet located on the left side of the first permanent magnet is vertically downward, and the magnetic pole directions of the two third permanent magnets are both horizontal to the right.

[0008] As a further solution of the present invention: the first permanent magnet, the second permanent magnet and the third permanent magnet are all arranged vertically in the length direction, horizontally in the width direction, and have the same length and width as rectangular parallelepiped; each permanent magnet is sequentially fitted along the thickness direction to form a rectangular permanent magnet group with the same length direction and the same width direction.

[0009] A method for calculating magnetic induction intensity, which uses the above-mentioned longitudinal and transverse wave electromagnetic ultrasonic transducer, includes the following calculation steps: S1. With the centroid of the first permanent magnet as the origin, a plane rectangular coordinate system O-XY parallel to the thickness direction of the first permanent magnet is established in the vertical plane, with the positive direction of the Y axis arranged vertically upward and the X axis arranged horizontally; S2. Calculate the effect of each permanent magnet on the point when the magnetization direction extends along the positive direction of the X axis. Magnetic induction intensity at S3. Calculate the effect of each permanent magnet on the point when the magnetization direction extends along the positive direction of the Y axis. Magnetic induction intensity at S4, based on the magnetic induction intensity calculated in step S2 and step S3, calculate the permanent magnet group at point The total magnetic induction intensity at .

[0010] As a further solution of the present invention: when the direction of the magnetization intensity extends along the positive direction of the X-axis, the general calculation formula of the magnetic induction intensity is expressed as follows: ; ; In the formula, Indicates at point The thickness of the permanent magnet at the current location that produces the magnetic field; Indicates at point The length of the permanent magnet at the current location that produces the magnetic field; Indicates that when the independent variable is and In the case of, when the permanent magnet is arranged horizontally in the direction of magnetization intensity, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of, when the permanent magnet is arranged vertically in the direction of magnetization intensity, at point The magnetic induction intensity in the vertical direction generated at ; Indicates the current magnetization intensity of the permanent magnet; represents the magnetic permeability of vacuum; represents pi; represents a logarithmic function with a natural constant as base;

[0011] As a further solution of the present invention: when the direction of the magnetization intensity extends along the positive direction of the Y axis, the general calculation formula of the magnetic induction intensity is expressed as follows: ; ; In the formula, Indicates that when the independent variable is and In the case of The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of The magnetic induction intensity generated in the vertical direction.

[0012] As a further solution of the present invention: the permanent magnet group is at point The total magnetic induction intensity at is calculated as follows: ; ; In the formula, Indicates that the permanent magnet group is at point The total magnetic induction intensity in the horizontal direction generated at Indicates that the permanent magnet group is at point The total magnetic induction intensity in the vertical direction generated at represents the thickness of the first permanent magnet (1); represents the thickness of the second permanent magnet (2); represents the thickness of the third permanent magnet (3); Indicates that when the independent variable is and In the case of the third permanent magnet (3) located on the left side of the first permanent magnet (1), when the third permanent magnet (3) is arranged vertically in the direction of magnetization intensity, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of the second permanent magnet (2) located on the left side of the first permanent magnet (1) when the magnetization intensity direction is horizontally arranged, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of the first permanent magnet (1) being arranged vertically in the direction of magnetization intensity, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of the second permanent magnet (2) located on the right side of the first permanent magnet (1) when the magnetization intensity direction is horizontally arranged, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of the third permanent magnet (3) located on the right side of the first permanent magnet (1), when the magnetization intensity direction is vertically arranged, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of the third permanent magnet (3) located on the left side of the first permanent magnet (1), when the third permanent magnet (3) is arranged vertically in the direction of magnetization intensity, at point The magnetic induction intensity in the vertical direction generated at ; Indicates that when the independent variable is and In the case of the second permanent magnet (2) located on the left side of the first permanent magnet (1) when the magnetization intensity direction is horizontally arranged, at point The magnetic induction intensity in the vertical direction generated at ; Indicates that when the independent variable is and In the case of the first permanent magnet (1) being arranged vertically in the direction of magnetization intensity, at point The magnetic induction intensity in the vertical direction generated at ; Indicates that when the independent variable is and In the case of the second permanent magnet (2) located on the right side of the first permanent magnet (1) when the magnetization intensity direction is horizontally arranged, at point The magnetic induction intensity in the vertical direction generated at ; Indicates that when the independent variable is and In the case of the third permanent magnet (3) located on the right side of the first permanent magnet (1), when the magnetization intensity direction is vertically arranged, at point The magnetic induction intensity generated in the vertical direction.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The longitudinal and transverse wave electromagnetic ultrasonic transducer of the present invention adopts a unique five-layer sandwich structure permanent magnet layout, that is, the first permanent magnet cooperates with the second permanent magnet symmetrical on both sides and the third permanent magnet on the outside, and the magnetic pole directions of different permanent magnets are arranged according to specific rules. At the same time, the longitudinal wave coil and the transverse wave coil are matched, so that the transducer can generate different Lorentz forces in the vertical direction and the horizontal direction, and then generate a variety of different modal signals. Its advantage is that it can adapt to complex and changeable detection conditions, meet diverse detection needs, provide a more flexible and comprehensive solution for detection work, and effectively improve the accuracy and reliability of detection.

[0014] 2. The direction of the first permanent magnet pole is horizontal to the left, and the direction of the second permanent magnet pole on the right is vertically upward, which further refines the specific direction of the permanent magnet pole, making the magnetic field distribution inside the transducer clearer and more specific. This precise setting of the magnetic pole direction helps to more accurately control and predict the magnetic field and force generated by the transducer in practical applications, thereby more stably generating the required different modal signals, further improving the stability and consistency of the detection effect.

[0015] 3. The first permanent magnet, the second permanent magnet and the third permanent magnet are all set to a specific shape and fit, that is, the length direction is vertical, the width direction is horizontal, and the length and width are the same, and they are fitted along the thickness direction to form a rectangular permanent magnet group with the same length and width. The advantage of this design is that it makes the structure of the permanent magnet more regular and unified, which is convenient for manufacturing and assembly. It is also conducive to simplifying the calculation and analysis of the magnetic field distribution, which facilitates the subsequent optimization and precise control of the transducer performance and enhances the stability and reliability of the entire transducer structure.

[0016] 4. The magnetic induction intensity calculation method is applied to the longitudinal and transverse wave electromagnetic ultrasonic transducer of the above-mentioned specific structure. By establishing a plane rectangular coordinate system with the centroid of the first permanent magnet as the origin, and calculating the magnetic induction intensity of each permanent magnet at a certain point under different magnetization directions in steps, the total magnetic induction intensity of the permanent magnet group at this point is finally obtained. Its advantage is that it provides a systematic and scientific calculation process for the magnetic field analysis of this specific transducer, which can accurately quantify the distribution of the magnetic field inside the transducer, and provides important theoretical basis and data support for the design optimization, performance evaluation and parameter adjustment of the transducer in actual detection applications.

[0017] 5. The general calculation formula of magnetic induction intensity when the magnetization intensity direction extends along the positive direction of the X-axis clarifies the quantitative relationship between the thickness, length, magnetization intensity and other parameters of the permanent magnet and the horizontal and vertical magnetic induction intensity generated at a certain point in this specific magnetization direction. Its advantage is that it provides an accurate mathematical model for calculating the magnetic induction intensity in this specific case, allowing researchers and engineers to accurately calculate the magnetic field distribution based on the actual parameters of the transducer permanent magnet, which helps to deeply understand and optimize the performance of the transducer in this magnetization direction.

[0018] 6. The general calculation formula of magnetic induction intensity when the magnetization intensity direction extends along the positive direction of the Y axis further improves the calculation system of magnetic induction intensity under different magnetization directions. Through these formulas, the relationship between the parameters of the permanent magnet and the horizontal and vertical magnetic induction intensity generated at a certain point under the magnetization direction is clarified, which helps to comprehensively and accurately analyze the magnetic field distribution of the transducer under various magnetization conditions, and provides more comprehensive theoretical calculation support for the multi-working condition application of the transducer.

[0019] 7. The specific calculation formula of the total magnetic induction intensity of the permanent magnet group at a certain point integrates the contribution of different permanent magnets to the magnetic induction intensity of the point in different magnetization directions. Its advantage is that it can comprehensively consider the structure and magnetization characteristics of the entire permanent magnet group, accurately calculate the total magnetic induction intensity of a specific point inside the transducer, and provide key data for a comprehensive evaluation of the magnetic field performance of the transducer, which helps to optimize the design and performance of the transducer as a whole, and ensure that it can work stably and efficiently in actual detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0021] Figure 2 Schematic diagram of the magnetic field direction of each permanent magnet in the present invention.

[0022] Figure 3 It is a side structural schematic diagram of the present invention.

[0023] Figure 4 It is a schematic diagram of the structure of the transverse wave coil in the present invention.

[0024] Figure 5 It is a schematic diagram of the structure of the longitudinal wave coil in the present invention.

[0025] Figure 6 It is a schematic diagram of the structure of the horizontally magnetized permanent magnet in the present invention.

[0026] Figure 7 It is a schematic diagram of the structure of the vertically magnetized permanent magnet in the present invention.

[0027] Figure 8 It is the simulation result of magnetic induction intensity of the permanent magnet group in the present invention.

[0028] Fig. 9 It is the calculation result of the magnetic induction intensity of the permanent magnet group in the present invention.

[0029] In the figure: 1. first permanent magnet; 2. second permanent magnet; 3. third permanent magnet; 4. transverse wave coil; 5. longitudinal wave coil; 6. piece to be tested. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] See also Figure 1 to Figure 5 In an embodiment of the present invention, a longitudinal and transverse wave electromagnetic ultrasonic transducer mainly includes a housing, a permanent magnet group and a coil. Five permanent magnets, all of which are rectangular, are installed inside the housing, namely a first permanent magnet 1, two second permanent magnets 2 and three third permanent magnets 3. The two second permanent magnets 2 are symmetrically arranged on both sides of the first permanent magnet 1, and a third permanent magnet 3 is arranged on the outside of each of the two second permanent magnets 2 to cooperate to form a five-layer sandwich structure. Figure 2 As shown, N represents the North Pole and S represents the South Pole. It can be seen that the magnetic pole direction of the first permanent magnet 1 is horizontal to the left, the magnetic pole direction of the second permanent magnet 2 located on the right side of the first permanent magnet 1 is vertically upward, and the magnetic pole directions of the two third permanent magnets 3 are both horizontal to the right. The first permanent magnet 1, the second permanent magnet 2 and the third permanent magnet 3 are all arranged vertically in the length direction, arranged horizontally in the width direction, and have the same length and width. The permanent magnets are sequentially attached along the thickness direction to form a permanent magnet group with the same length direction and the same width direction.

[0032] like Figure 3 As shown, a longitudinal wave coil 5 and a transverse wave coil 4 are arranged below the permanent magnet. Figure 4 As shown, the two transverse wave coils 4 are both single-fold coils in the shape of a U-shaped U-shaped coil, and the two are electrically connected to each other. One fold of the two transverse wave coils 4 is located directly below the corresponding second permanent magnet 2, and the other folds do not interact with the second permanent magnet 2 and other permanent magnets. Figure 5 As shown, the longitudinal wave coil 5 is a single meander coil, one of which is arranged below the first permanent magnet 1, and the remaining folded edges do not interact with the first permanent magnet 1 and other permanent magnets.

[0033] In the above arrangement, the permanent magnet group can generate high-intensity horizontal magnetic field and vertical magnetic field at the same time. The horizontal magnetic field is located below the first permanent magnet 1 and the two third permanent magnets 3, and the vertical magnetic field is located below the two second permanent magnets 2. By adjusting the thickness of different permanent magnets, it can be ensured that the same intensity and width of the horizontal and longitudinal wave signals are generated. Figure 2 As shown, the thickness of the third permanent magnet 3 on the left is , the thickness of the second permanent magnet 2 on the left is , the thickness of the first permanent magnet 1 is , the thickness of the second permanent magnet 2 on the right is , the thickness of the third permanent magnet 3 on the right is , the width of each permanent magnet is the same, and the height h Same.

[0034] When RF pulse currents are respectively passed through the transverse wave coil 4 and the longitudinal wave coil 5, eddy currents arranged alternately are induced on the surface of the test piece 6. The eddy currents interact with the horizontal magnetic field, and the particle vibration direction is consistent downward, forming a Lorentz force perpendicular to the direction of the test piece, and achieving efficient excitation and reception of ultrasonic longitudinal waves. The eddy currents interact with the vertical magnetic field, and the particle vibration direction is consistent to the left, forming a Lorentz force acting on the test piece 6, and achieving efficient excitation and reception of ultrasonic transverse waves. At the same time, since the particle vibration direction is consistent, unnecessary energy loss is reduced, and the transducer efficiency of the transducer is improved.

[0035] According to the needs during use, the excitation current can be passed through the transverse wave coil 4 or the longitudinal wave coil 5 separately to generate transverse wave and longitudinal wave signals respectively; or the excitation current can be passed through the transverse and longitudinal wave coils 5 at the same time to generate transverse and longitudinal wave signals at the same time.

[0036] The magnetic induction intensity calculation method of the present invention comprises the following calculation steps: 1. Establish a plane rectangular coordinate system O-XY.

[0037] like Figure 6 and Figure 7As shown, with the centroid of the first permanent magnet 1 as the origin, a plane rectangular coordinate system O-XY parallel to the thickness direction of the first permanent magnet 1 is established in the vertical plane, with the positive Y axis arranged vertically upward and the X axis arranged horizontally.

[0038] 2. Horizontal magnetization.

[0039] like Figure 6 As shown, the calculation of the effect of each permanent magnet on the point when the magnetization direction extends along the positive direction of the X axis is The magnetic induction intensity at .

[0040] When the direction of magnetization intensity extends along the positive direction of the X-axis, the general calculation formula of magnetic induction intensity is expressed as follows: (1); (2).

[0041] 3. Plumb magnetization.

[0042] like Figure 7 As shown, the calculation of the effect of each permanent magnet on the point when the magnetization direction extends along the positive direction of the Y axis The magnetic induction intensity at .

[0043] When the direction of magnetization intensity extends along the positive direction of the Y axis, the general calculation formula of magnetic induction intensity is expressed as follows: (3); (4).

[0044] 4. Calculate the total magnetic induction intensity.

[0045] Based on the magnetic induction intensity calculated in the above steps, calculate the permanent magnet group at point The total magnetic induction intensity at .

[0046] The permanent magnet group is at point The total magnetic induction intensity at is calculated as follows: (5); (6).

[0047] In this embodiment, the material of each permanent magnet is N52 magnet, and the magnetization strength of each permanent magnet is 5.5×10 -7 A / m, the vacuum permeability of each permanent magnet is 4π×10 -7 T·m / A. At the same time, the left The value is 2mm, the left side The value is 4mm. The value is 8mm, the right side The value is 4mm, the right side The value is 2mm, the width of each permanent magnet is 20mm, and the height of each permanent magnet is h At the same time, the longitudinal wave coil 5 and the transverse wave coil 4 are arranged 1 mm below the permanent magnet group, and the thickness of the coil itself is negligible. It can be considered that the two coils are both in the 1 mm plane.

[0048] The longitudinal and transverse wave electromagnetic ultrasonic transducer model of the present invention is established in the finite element analysis software, and the above data is input into the longitudinal and transverse wave electromagnetic ultrasonic transducer model to simulate and calculate the points. The magnetic induction intensity is generated at the location, and the simulation results are as follows Figure 8 The magnetic induction intensity calculated by the calculation method of the present invention is shown as Fig. 9 shown.

[0049] Depend on Fig. 9 It can be seen that when the offset distance D from the coordinate origin along the X axis is in the interval [-8,-4] and [4,8], the vertical component, that is, the total magnetic induction intensity along the vertical direction, is x The derivative of is close to 0. When D is in the range of [-4,4], the horizontal component, that is, the total magnetic induction intensity along the horizontal direction, is x The partial derivative of is close to 0, so it can be considered that the magnetic induction intensity does not change much at this time. Figure 8 The simulation results are the same as those in . Figure 8 and Fig. 9 It can be seen that the calculation results of the present invention have the same changing trend as the simulation results, which verifies the correctness of the magnetic induction intensity model in the present invention.

[0050] When the test piece is made of non-ferromagnetic material, the working mechanism of the electromagnetic ultrasonic transducer in the present invention to generate ultrasonic waves is mainly the Lorentz force. When a high-frequency excitation current is applied, induced eddy currents will be formed on the surface of the test piece 6. These induced eddy currents will be affected by the Lorentz force under the action of the external magnetic field, thereby generating vibrations and forming ultrasonic waves. The transverse wave intensity generated on the surface of the test piece is Size: (7); The longitudinal wave intensity generated on the surface of the test piece Size: (8); By the coil length The corresponding wave intensity can be calculated by integrating the shear wave coil 4 and the longitudinal wave coil 5. Therefore, when the corresponding range of the shear wave coil 4 and the longitudinal wave coil 5 is the same, and the horizontal component and vertical component of the magnetic induction intensity corresponding to the two are the same, the transverse and longitudinal wave intensities generated are the same. The main reason affecting the generation of longitudinal and transverse wave modes is the arrangement of the magnets and coils. The current density will only affect the intensity of the wave, and the influence on shear waves and longitudinal waves is the same.

[0051] When the test piece is a ferromagnetic material, the working mechanism of the electromagnetic ultrasonic transducer in the present invention to generate ultrasonic waves is mainly the sum of the Lorentz force and the magnetostrictive force. The Lorentz force has been introduced above, and the principle of the magnetostrictive force to generate ultrasonic waves is mainly that the magnetic material changes in size under the action of the magnetic field. When an alternating magnetic field is applied to the magnetostrictive material, the tiny magnetic domains in the material will flip with the change of the magnetic field, resulting in macroscopic strain, which can generate ultrasonic waves.

[0052] Magnetostrictive force F The magnetostrictive stress along the X-axis can be , magnetostrictive stress along the Y axis And the geometric dimensions of the material are calculated to obtain: Then the shear wave intensity generated on the surface of the test piece is The size is: (9); The longitudinal wave intensity generated on the surface of the test piece The size is: (10); The starting position of the transverse wave coil and the ending position of the transverse wave coil refer to the moving distance from one side of the second permanent magnet to the other side of the second permanent magnet along the thickness direction of the second permanent magnet, that is, the thickness of the second permanent magnet. r 2. Similarly, the starting position of the longitudinal wave coil and the ending position of the longitudinal wave coil refer to the moving distance from one side of the first permanent magnet to the other side of the first permanent magnet along the thickness direction of the first permanent magnet, that is, the thickness of the first permanent magnet. r 1.

[0053] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A longitudinal and transverse wave electromagnetic ultrasonic transducer, characterized in that: The invention comprises a first permanent magnet (1) and two second permanent magnets (2) symmetrically arranged on both sides of the first permanent magnet (1); a third permanent magnet (3) is arranged outside each of the two second permanent magnets (2) to cooperate to form a five-layer sandwich structure; the magnetic pole directions of the first permanent magnet (1) and the two third permanent magnets (3) are arranged in a horizontal direction, and the magnetic pole directions of the two third permanent magnets (3) are opposite to the magnetic pole directions of the first permanent magnet (1); the magnetic pole directions of the two second permanent magnets (2) are arranged in a vertical direction, and the magnetic pole directions of the two second permanent magnets (2) are opposite to each other; a longitudinal wave coil (5) is arranged below the first permanent magnet (1), and the longitudinal wave coil (5) cooperates with the first permanent magnet (1) to generate a first Lorentz force acting on the test piece to be tested in the vertical direction; and a transverse wave coil (4) is arranged below the two second permanent magnets (2), and the transverse wave coil (4) cooperates with the second permanent magnet (2) to generate a second Lorentz force acting horizontally on the test piece to be tested.

2. A longitudinal and transverse wave electromagnetic ultrasonic transducer according to claim 1, characterized in that: The magnetic pole direction of the first permanent magnet (1) is horizontally facing leftward, the magnetic pole direction of the second permanent magnet (2) located on the right side of the first permanent magnet (1) is vertically facing upward, the magnetic pole direction of the second permanent magnet (2) located on the left side of the first permanent magnet (1) is vertically facing downward, and the magnetic pole directions of the two third permanent magnets (3) are both horizontally facing rightward.

3. A longitudinal and transverse wave electromagnetic ultrasonic transducer according to claim 2, characterized in that: The first permanent magnet (1), the second permanent magnet (2) and the third permanent magnet (3) are all arranged vertically in the length direction and horizontally in the width direction, and are in the shape of a cuboid with the same length and width; the permanent magnets are sequentially bonded together in the thickness direction to form a cuboid permanent magnet group with the same length direction and the same width direction.

4. A method for calculating magnetic induction intensity, the method for calculating magnetic induction intensity using a longitudinal and transverse wave electromagnetic ultrasonic transducer as claimed in claim 3, characterized in that: The calculation steps include: S1. With the centroid of the first permanent magnet (1) as the origin, a plane rectangular coordinate system O-XY is established in a vertical plane and is parallel to the thickness direction of the first permanent magnet (1), with the positive direction of the Y axis arranged vertically upward and the positive direction of the X axis arranged horizontally to the right; S2. Calculate the effect of each permanent magnet on the point when the magnetization direction extends along the positive direction of the X axis. The magnetic induction intensity at S3. Calculate the effect of each permanent magnet on the point when the magnetization direction extends along the positive direction of the Y axis. The magnetic induction intensity at S4, based on the magnetic induction intensity calculated in step S2 and step S3, calculate the permanent magnet group at point The total magnetic induction intensity at .

5. A method for calculating magnetic induction intensity according to claim 4, characterized in that: When the direction of magnetization intensity extends along the positive direction of the X-axis, the general calculation formula of magnetic induction intensity is expressed as follows: ； ； In the formula, Indicates at point The thickness of the permanent magnet at the current location that produces the magnetic field; Indicates at point The length of the permanent magnet at the current location that produces the magnetic field; Indicates that when the independent variable is and In the case of, when the permanent magnet is arranged horizontally in the direction of magnetization intensity, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of, when the permanent magnet is arranged vertically in the direction of magnetization intensity, at point The magnetic induction intensity in the vertical direction generated at ; Indicates the current magnetization intensity of the permanent magnet; represents the magnetic permeability of vacuum; represents pi; Represents a logarithmic function with a natural constant as base.

6. A method for calculating magnetic induction intensity according to claim 5, characterized in that: When the direction of magnetization intensity extends along the positive direction of the Y axis, the general calculation formula of magnetic induction intensity is expressed as follows: ； ； In the formula, Indicates that when the independent variable is and In the case of The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of The magnetic induction intensity generated in the vertical direction.

7. A method for calculating magnetic induction intensity according to claim 6, characterized in that: Permanent magnet group at point The total magnetic induction intensity at is calculated as follows: ； ； In the formula, Indicates that the permanent magnet group is at point The total magnetic induction intensity in the horizontal direction generated at Indicates that the permanent magnet group is at point The total magnetic induction intensity in the vertical direction generated at represents the thickness of the first permanent magnet (1); represents the thickness of the second permanent magnet (2); represents the thickness of the third permanent magnet (3); Indicates that when the independent variable is and In the case of the third permanent magnet (3) located on the left side of the first permanent magnet (1), when the third permanent magnet (3) is arranged vertically in the direction of magnetization intensity, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of the second permanent magnet (2) located on the left side of the first permanent magnet (1) when the magnetization intensity direction is horizontally arranged, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of the first permanent magnet (1) being arranged vertically in the direction of magnetization intensity, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of the second permanent magnet (2) located on the right side of the first permanent magnet (1) when the magnetization intensity direction is horizontally arranged, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of the third permanent magnet (3) located on the right side of the first permanent magnet (1), when the magnetization intensity direction is vertically arranged, at point The magnetic induction intensity in the horizontal direction generated at ; Indicates that when the independent variable is and In the case of the third permanent magnet (3) located on the left side of the first permanent magnet (1), when the third permanent magnet (3) is arranged vertically in the direction of magnetization intensity, at point The magnetic induction intensity in the vertical direction generated at ; Indicates that when the independent variable is and In the case of the second permanent magnet (2) located on the left side of the first permanent magnet (1) when the magnetization intensity direction is horizontally arranged, at point The magnetic induction intensity in the vertical direction generated at ; Indicates that when the independent variable is and In the case of the first permanent magnet (1) being arranged vertically in the direction of magnetization intensity, at point The magnetic induction intensity in the vertical direction generated at ; Indicates that when the independent variable is and In the case of the second permanent magnet (2) located on the right side of the first permanent magnet (1) when the magnetization intensity direction is horizontally arranged, at point The magnetic induction intensity in the vertical direction generated at ; Indicates that when the independent variable is and In the case of the third permanent magnet (3) located on the right side of the first permanent magnet (1), when the magnetization intensity direction is vertically arranged, at point The magnetic induction intensity generated in the vertical direction.

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