Three-dimensional variable-angle nondestructive testing probe and plane nondestructive testing method for multilayer material

Abstract

The invention discloses a three-dimensional variable-angle nondestructive testing probe and a planar nondestructive testing method of a multilayer material, and belongs to the technical field of signal detection. Comprising a shell, a transverse variable-angle operating rod, a transverse variable-angle straight gear, a longitudinal variable-angle operating rod and a longitudinal variable-angle straight gear, a piezoelectric ceramic carrier is arranged in the shell, the upper surface of the piezoelectric ceramic carrier is tooth-shaped, and a piezoelectric ceramic probe is arranged at the bottom of the piezoelectric ceramic carrier; the transverse variable-angle straight gear is horizontally arranged in the shell and located on the top of the piezoelectric ceramic carrier, and one end of the transverse variable-angle operating rod vertically penetrates through the shell to be connected with the transverse variable-angle straight gear. The longitudinal variable-angle straight gear is vertically arranged in the shell and located on one side of the piezoelectric ceramic carrier. One end of the longitudinal variable-angle operating rod horizontally penetrates through the shell to be connected with the longitudinal variable-angle straight gear, and the transverse variable-angle straight gear and the longitudinal variable-angle straight gear are meshed with the piezoelectric ceramic carrier. The detection dimension can be improved, and the problem that the detection dimension of existing material nondestructive detection is limited is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of signal detection, and in particular to a three-dimensional variable angle nondestructive detection probe and a planar nondestructive detection method for multilayer materials. Background Art

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

[0003] Advanced composite materials are widely used in the aerospace field. Composite materials have become one of the important targets for the development of composite materials due to their low cost and corrosion resistance. However, during the use of composite materials, due to fatigue damage, impact and other external influences, defects such as cracks, holes, debonding, etc. will occur to varying degrees. Composite materials with defects pose a safety hazard, so it is very important to perform non-destructive testing on composite materials.

[0004] In order to solve the above problems, defect detection of composite materials is often carried out through non-destructive testing probes. Commonly used non-destructive testing probes include oblique probes. Although this type of probe can successfully transmit ultrasonic waves, its fixed angle can only be used to detect samples with certain specific parameters. When the test sample is replaced, the oblique probe needs to be customized again.

[0005] On this basis, variable angle probes came into being, but their transmitting probes and receiving probes need to be on the same straight line as the defect to facilitate signal transmission and reception. This type of probe is usually used for straight line detection and has limited detection dimensions. Summary of the invention

[0006] In order to address the deficiencies in the prior art, the present invention provides a three-dimensional variable angle nondestructive testing probe and a planar nondestructive testing method for multi-layer materials, which integrates spur gears and gears into the angle adjustment of the probe. The angle adjustment of the probe can be achieved simply by adjusting the operating lever, greatly reducing the difficulty of operation.

[0007] In a first aspect, the present invention provides a three-dimensional variable angle nondestructive testing probe;

[0008] A three-dimensional variable angle nondestructive testing probe, comprising:

[0009] A shell, wherein a piezoelectric ceramic carrier is arranged inside the shell, and the upper surface of the piezoelectric ceramic carrier is toothed; a piezoelectric ceramic probe is arranged at the bottom of the piezoelectric ceramic carrier;

[0010] A transverse angle-changing module, the transverse angle-changing module comprising a transverse angle-changing operating rod and a transverse angle-changing spur gear, the transverse angle-changing spur gear being horizontally arranged inside the housing and located on the top of the piezoelectric ceramic carrier, one end of the transverse angle-changing operating rod vertically passing through the housing to be connected to the transverse angle-changing spur gear, and the transverse angle-changing spur gear being meshed with the piezoelectric ceramic carrier;

[0011] A longitudinal angle-changing module, the longitudinal angle-changing module comprising a longitudinal angle-changing operating lever and a longitudinal angle-changing spur gear,

[0012] The longitudinal angle-changing spur gear is vertically arranged inside the shell and located on one side of the piezoelectric ceramic carrier; one end of the longitudinal angle-changing operating rod horizontally passes through the shell and is connected to the longitudinal angle-changing spur gear, and the longitudinal angle-changing spur gear is meshed with the piezoelectric ceramic carrier.

[0013] In some embodiments, a first movable groove is opened at the top of the shell along the width direction of the shell, and one end of the lateral angle-changing operating rod vertically passes through the first movable groove and is connected to the lateral angle-changing spur gear.

[0014] In some embodiments, a transverse scale is provided on the top of the housing, and the transverse scale is located on one side of the first moving groove.

[0015] In some embodiments, a second movable groove is formed on the side wall of the shell along the height direction of the shell, and one end of the longitudinal angle-changing operating rod horizontally passes through the second movable groove and is connected to the longitudinal angle-changing spur gear.

[0016] In some embodiments, a side wall of the housing is provided with a longitudinal scale, and the longitudinal scale is located on one side of the second movable groove.

[0017] In some embodiments, a cavity is provided inside the housing, and the piezoelectric ceramic carrier is located inside the cavity;

[0018] A coupling agent is placed between the cavity and the piezoelectric ceramic probe conductor.

[0019] In some embodiments, the housing is made of quartz glass.

[0020] In a second aspect, the present invention provides a method for planar nondestructive testing of multilayer materials;

[0021] A planar nondestructive testing method for multilayer materials, based on the above-mentioned three-dimensional variable angle nondestructive testing probe, comprises:

[0022] Obtaining the elastic modulus and density of the multilayer material and calculating the longitudinal wave velocity of the multilayer material, obtaining the elastic modulus and density of the piezoelectric ceramic probe and calculating the longitudinal wave velocity of the piezoelectric ceramic probe;

[0023] The number of layers and layer height of the multilayer material, the distance between the defect on the multilayer material and the center of the piezoelectric ceramic probe, and the distance between the center of the piezoelectric ceramic probe and the top layer of the multilayer material are obtained. Combined with the longitudinal wave velocity of the multilayer material and the longitudinal wave velocity of the piezoelectric ceramic probe, the required adjustment angles of the lateral variable angle module and the longitudinal variable angle module are determined.

[0024] In some embodiments, the angle that needs to be adjusted for the lateral variable angle module is obtained based on the longitudinal wave velocity of the multilayer material, the longitudinal wave velocity of the piezoelectric ceramic probe, the distance between the defect on the multilayer material and the center of the piezoelectric ceramic probe in the y direction, and the distance between the center of the piezoelectric ceramic probe and the top layer of the multilayer material.

[0025] In some embodiments, the angle that needs to be adjusted for the lateral variable angle module is obtained based on the longitudinal wave velocity of the multilayer material, the longitudinal wave velocity of the piezoelectric ceramic probe, the distance between the defect on the multilayer material and the center of the piezoelectric ceramic probe in the x-direction, and the spacing between the center of the piezoelectric ceramic probe and the top layer of the multilayer material.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The technical solution provided by the present invention designs a three-dimensional variable angle non-destructive testing probe. Through the meshing of the lateral variable angle gear, the longitudinal variable angle gear and the piezoelectric ceramic carrier, the required angle can be adjusted only by moving the operating lever up, down, left and right, which greatly reduces the difficulty of operation and improves the dimension of detection.

[0028] 2. The technical solution provided by the present invention can perform real-time three-dimensional adjustment of the probe angle according to factors such as the number of layers, thickness and defect location of the material to be tested, meet the non-destructive testing needs of different types of materials to be tested, improve versatility, and be more in line with the actual situation of the material to be tested. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0030] Figure 1 A schematic diagram of the three-dimensional structure of a three-dimensional variable angle nondestructive testing probe provided by an embodiment of the present invention;

[0031] Figure 2 A schematic diagram of various parts of a three-dimensional variable angle nondestructive testing probe provided by an embodiment of the present invention;

[0032] Figure 3 A schematic diagram of a yz-plane cross-section of a three-dimensional variable angle nondestructive testing probe provided by an embodiment of the present invention;

[0033] Figure 4A schematic diagram of the xz plane cross section of a three-dimensional variable angle nondestructive testing probe provided by an embodiment of the present invention;

[0034] Figure 5 A schematic diagram of the change of the yz direction angle according to the number of material layers and thickness in the planar nondestructive testing method provided by an embodiment of the present invention;

[0035] Figure 6 A schematic diagram of changing the angle in the xz direction according to the number of material layers and thickness in the planar nondestructive testing method provided by an embodiment of the present invention;

[0036] In the figure: 1. Shell; 2. Lateral variable angle operating lever; 3. Lateral scale; 4. Power interface; 5. Longitudinal variable angle operating lever; 6. Longitudinal scale; 7. Piezoelectric ceramic probe; 8. Piezoelectric ceramic carrier; 9. Lateral variable angle spur gear; 10. Longitudinal variable angle spur gear; 11. Cavity; 12. Defect position; 13. Left defect; 14. Right defect. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0039] Embodiment 1

[0040] The existing variable angle probe can only realize linear nondestructive testing, which has certain limitations; therefore, the present invention provides a three-dimensional variable angle nondestructive testing probe, which utilizes the cooperation of spur gears and a piezoelectric ceramic carrier 8 with a hemispherical tooth surface to realize multi-dimensional adjustment of the probe in the xyz direction.

[0041] Next, combine Figure 1-Figure 6 , a three-dimensional variable angle nondestructive testing probe disclosed in this embodiment is described in detail.

[0042] The three-dimensional variable angle nondestructive testing probe comprises a shell 1, a lateral variable angle module and a longitudinal variable angle module, the lateral variable angle module comprises a lateral variable angle operating lever 1 and a lateral variable angle spur gear 9, and the longitudinal variable angle module comprises a longitudinal variable angle operating lever 5 and a longitudinal variable angle spur gear 10; a piezoelectric ceramic carrier 8 is placed inside the shell 1, the piezoelectric ceramic carrier 8 is hemispherical, and the upper surface of the piezoelectric ceramic carrier 8 is toothed, and a piezoelectric ceramic probe 7 is fixed to the bottom; a first movable groove is opened on the top of the shell 1 along the width direction of the shell 1, and a second movable groove is opened on the side wall of the shell 1 along the height direction of the shell 1; a power interface 4 is provided on the side wall of the shell 1, and the power interface 4 is used to connect a power source.

[0043] The transverse angle-changing spur gear 9 is horizontally installed inside the shell 1 and is located above the piezoelectric ceramic carrier 8. One end of the transverse angle-changing operating rod 1 vertically passes through the first movable groove and is connected to the transverse angle-changing spur gear 9, and the transverse angle-changing spur gear 9 is meshed with the piezoelectric ceramic carrier 8; by moving the transverse operating rod left and right, the transverse angle-changing spur gear 9 moves left and right, and then the piezoelectric ceramic carrier 8 rotates along the xz direction to achieve transverse angle change; the longitudinal angle-changing spur gear 10 is vertically installed inside the shell 1 and is located on one side of the piezoelectric ceramic carrier 8; one end of the longitudinal angle-changing operating rod 5 horizontally passes through the second movable groove and is connected to the longitudinal angle-changing spur gear 10; the longitudinal angle-changing spur gear 10 is meshed with the piezoelectric ceramic carrier 8; when the longitudinal angle-changing operating rod 5 is moved up and down, the longitudinal angle-changing spur gear 10 also moves up and down to make the piezoelectric ceramic carrier 8 rotate along the yz direction to achieve longitudinal angle change.

[0044] Here, since the piezoelectric ceramic carrier 8 is in a hemispherical tooth shape, when the lateral variable angle module or the longitudinal variable angle module is adjusted, the other variable angle module will not be affected.

[0045] In this embodiment, the housing 1 is made of quartz glass.

[0046] As an embodiment, the interior of the housing 1 has a cavity 11, and the cavity 11 is in the shape of two vertically crossed and connected cylinders. The piezoelectric ceramic carrier 8 is located inside the cavity 11, and the first movable groove and the second movable groove are connected to the cavity 11. The lateral angle-changing operating rod 1 and the longitudinal angle-changing operating rod 5 respectively pass through the cavity 11 and engage with the piezoelectric ceramic carrier 8.

[0047] The cylindrical cavity 11 is only used to facilitate the direction adjustment of the hemispherical toothed piezoelectric ceramic carrier 8 under the action of the variable angle module, and will not affect the meshing between the variable angle module and the hemispherical toothed piezoelectric ceramic carrier 8. A coupling agent such as glycerin can be injected into the cavity 11 to improve the efficiency of sound waves transmitting into the shell 1. At the same time, glycerin can act as a lubricant to reduce the contact force generated by the meshing between the variable angle module and the hemispherical toothed piezoelectric ceramic carrier 8.

[0048] In order to further quantify the angle to be adjusted, as an implementation mode, the top of the shell 1 is engraved with a transverse scale 3, which is located on one side of the first movable groove, and the transverse scale 3 is bidirectional 0°-90°. When operating the transverse variable angle module, the transverse variable angle operating lever 1 moves 1 grid to the left / right, and the piezoelectric ceramic carrier 8 rotates 10° counterclockwise / clockwise along the y-axis; the side wall of the shell 1 is engraved with a longitudinal scale 6, which is located on one side of the second movable groove, and the longitudinal scale 6 is unidirectional 0°-90°. When operating the longitudinal variable angle module, the longitudinal variable angle operating lever 5 moves 1 grid up / down, and the piezoelectric ceramic carrier 8 rotates 10° counterclockwise / clockwise along the x-axis.

[0049] Embodiment 2

[0050] Based on the three-dimensional variable angle nondestructive testing probe described in the first embodiment, this embodiment discloses a planar nondestructive testing method for multilayer materials, comprising the following steps:

[0051] S1. Obtain the elastic modulus and density of the multilayer material and calculate the longitudinal wave velocity of the multilayer material, obtain the elastic modulus and density of the piezoelectric ceramic probe 7 and calculate the longitudinal wave velocity of the piezoelectric ceramic probe 7; based on Snell's law, according to the longitudinal wave velocity of the multilayer material and the longitudinal wave velocity of the piezoelectric ceramic probe 7, determine the relationship between the incident angle (i.e., the angle to be adjusted of the longitudinal variable angle module) and the refraction angle.

[0052] Among them, the longitudinal wave velocity of the piezoelectric ceramic probe 7 is expressed as:

[0053]

[0054] The longitudinal wave velocity of a multilayer material is expressed as:

[0055]

[0056] In the formula, E 1 represents the elastic modulus of the piezoelectric ceramic probe 7, ρ 1 represents the density of the piezoelectric ceramic probe 7, E 2 represents the elastic modulus of the multilayer material, ρ 2 Indicates the density of a multi-layer material.

[0057] The relationship between the required adjustment angle of the longitudinal variable angle module and the refraction angle is expressed as:

[0058]

[0059] In the formula, θ 1 Indicates the required adjustment angle of the longitudinal variable angle module, θ 2 Represents the refraction angle.

[0060] S2, obtaining the number of layers and layer height of the multilayer material, the distance between the defect on the multilayer material and the center of the piezoelectric ceramic probe 7, and the distance between the center of the piezoelectric ceramic probe 7 and the top layer of the multilayer material, and combining the longitudinal wave velocity of the multilayer material and the longitudinal wave velocity of the piezoelectric ceramic probe 7 to determine the angles to be adjusted for the lateral variable angle module and the longitudinal variable angle module. Specifically including:

[0061] S201, using the number of layers and layer height of the multilayer material, the distance between the defect on the multilayer material and the center of the piezoelectric ceramic probe 7 in the x direction, and the distance between the center of the piezoelectric ceramic probe 7 and the top layer of the multilayer material, combined with the longitudinal wave velocity of the multilayer material and the longitudinal wave velocity of the piezoelectric ceramic probe 7, determine the required adjustment angle of the longitudinal variable angle module. Figure 5 As shown, the specific process is as follows:

[0062] (1) According to the distance between the defect on the multilayer material and the center of the piezoelectric ceramic probe 7 in the x-direction, the spacing between the center of the piezoelectric ceramic probe 7 and the top layer of the multilayer material, and the required adjustment angle of the longitudinal variable angle module, the distance between the defect and the ultrasonic incident point in the x-direction can be determined, which is expressed as:

[0063] l 1 = lh 1 tanθ 1 ;

[0064] In the formula, l 1 represents the distance between the defect and the ultrasonic incident point in the x direction, l represents the distance between the defect center on the multilayer material and the center of the piezoelectric ceramic probe 7 in the x direction, and h 1 represents the distance between the center of the piezoelectric ceramic probe 7 and the top layer of the multilayer material, θ 1 Indicates the angle that the longitudinal variable angle module needs to adjust, that is, the incident angle.

[0065] (2) According to the number of layers, layer height, and the distance between the defect and the ultrasonic incident point in the x direction of the multilayer material, the refraction angle θ can be obtained. 2 The specific representation is:

[0066]

[0067] Wherein, n represents the number of layers of the multilayer material, and h represents the layer height of the multilayer material.

[0068] Based on the above formula, we can finally get:

[0069]

[0070] In the actual application process, c 1 、c 2 , l, h 1 Substitute the specific values ​​of n, h and h into the above formula to obtain the angle θ that the longitudinal variable angle module needs to adjust for the multilayer material with n layers and nh thickness. 1 .

[0071] S201, using the number of layers and layer height of the multilayer material, the distance between the defect on the multilayer material and the center of the piezoelectric ceramic probe 7 in the y direction, and the distance between the center of the piezoelectric ceramic probe 7 and the top layer of the multilayer material, combined with the longitudinal wave velocity of the multilayer material and the longitudinal wave velocity of the piezoelectric ceramic probe 7, determine the angle to be adjusted for the lateral variable angle module. The specific process is as follows:

[0072] (1) According to the distance between the defect on the multilayer material and the center of the piezoelectric ceramic probe 7 in the y direction, the spacing between the center of the piezoelectric ceramic probe 7 and the top layer of the multilayer material, and the required adjustment angle of the lateral variable angle module, the distance between the defect and the ultrasonic incident point in the y direction can be determined, which is expressed as:

[0073] l 2 = l 3 -h 1 tanθ 3 ;

[0074] Combination Figure 6 , where l 2 represents the y-direction distance between the left defect 13 and the ultrasonic incident point, l 3 represents the y-direction distance between the left defect 13 and the center of the piezoelectric ceramic probe 7, h 1 represents the distance between the center of the piezoelectric ceramic probe 7 and the top layer of the multilayer material.

[0075] (2) According to the number of layers, layer height, and the distance between the defect and the ultrasonic incident point in the y direction of the multilayer material, the refraction angle θ can be obtained. 4 The specific representation is:

[0076]

[0077] Wherein, n represents the number of layers of the multilayer material, and h represents the layer height of the multilayer material.

[0078] Based on the above formula, we can finally get:

[0079]

[0080] In the actual application process, c 1 、c 2 , l 3 、h 1 Substituting the specific values ​​of n, h and h into the above formula, we can obtain the angle θ that the lateral variable angle module needs to adjust for a multilayer material with n layers and a thickness of nh. 3 .

[0081] In the actual application process, c 1 、c 2 , l 3 、h 1 Substituting the specific values ​​of n, h and h into the above formula, we can obtain the angle θ that the lateral variable angle module needs to adjust for a multilayer material with n layers and a thickness of nh. 3 .

[0082] Furthermore, since the lateral variable angle module can adjust the angle of the piezoelectric ceramic carrier 8 in both clockwise and counterclockwise directions, for a sample with a defect located on the right side of the probe center, the lateral variable angle module angle θ 5 The relevant expression is:

[0083]

[0084] In the formula, l 4 represents the distance between the right defect 14 and the center of the piezoelectric ceramic probe 7 in the y direction, θ 5 Indicates the incident angle that needs to be adjusted when the lateral variable angle module detects the defect 14 on the right side.

[0085] S3. The power supply supplies power to the three-dimensional variable angle nondestructive testing probe through the power interface 4, and the three-dimensional variable angle nondestructive testing probe with the adjusted angle is used to perform planar nondestructive testing on the multi-layer material.

[0086] Here, the detection principle of the three-dimensional variable angle nondestructive testing probe is a well-known technology for those skilled in the art, and this embodiment does not improve it, so it will not be repeated here. The description of each embodiment in the above embodiments has different emphases, and the parts not described in detail in one embodiment can refer to the relevant description of other embodiments.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A three-dimensional variable angle nondestructive testing probe, characterized in that: include: A shell, wherein a piezoelectric ceramic carrier is arranged inside the shell, and the upper surface of the piezoelectric ceramic carrier is toothed; a piezoelectric ceramic probe is arranged at the bottom of the piezoelectric ceramic carrier; A transverse angle-changing module, the transverse angle-changing module comprising a transverse angle-changing operating rod and a transverse angle-changing spur gear, the transverse angle-changing spur gear being horizontally arranged inside the housing and located on the top of the piezoelectric ceramic carrier, one end of the transverse angle-changing operating rod vertically passing through the housing to be connected to the transverse angle-changing spur gear, and the transverse angle-changing spur gear being meshed with the piezoelectric ceramic carrier; A longitudinal angle-changing module, the longitudinal angle-changing module comprising a longitudinal angle-changing operating rod and a longitudinal angle-changing spur gear, the longitudinal angle-changing spur gear being vertically arranged inside the shell and located on one side of the piezoelectric ceramic carrier; one end of the longitudinal angle-changing operating rod horizontally passes through the shell and is connected to the longitudinal angle-changing spur gear, and the longitudinal angle-changing spur gear is meshed with the piezoelectric ceramic carrier.

2. The three-dimensional variable angle nondestructive testing probe according to claim 1, characterized in that: A first moving groove is formed at the top of the housing along the width direction of the housing, and one end of the lateral angle-changing operating rod vertically passes through the first moving groove and is connected to the lateral angle-changing spur gear.

3. The three-dimensional variable angle nondestructive testing probe according to claim 2, characterized in that: A transverse scale is arranged on the top of the shell, and the transverse scale is located on one side of the first moving groove.

4. The three-dimensional variable angle nondestructive testing probe according to claim 1, characterized in that: A second moving groove is formed on the side wall of the shell along the height direction of the shell, and one end of the longitudinal angle-changing operating rod horizontally passes through the second moving groove and is connected to the longitudinal angle-changing spur gear.

5. The three-dimensional variable angle nondestructive testing probe according to claim 4, characterized in that: A longitudinal scale is provided on the side wall of the shell, and the longitudinal scale is located at one side of the second moving groove.

6. The three-dimensional variable angle nondestructive testing probe according to claim 1, characterized in that: A cavity is provided inside the shell, and the piezoelectric ceramic carrier is located inside the cavity; A coupling agent is placed between the cavity and the piezoelectric ceramic probe conductor.

7. The three-dimensional variable angle nondestructive testing probe according to claim 1, characterized in that: The housing is made of quartz glass.

8. A planar nondestructive testing method for multilayer materials, based on the three-dimensional variable angle nondestructive testing probe according to any one of claims 1 to 7, characterized in that: include: Obtaining the elastic modulus and density of the multilayer material and calculating the longitudinal wave velocity of the multilayer material, obtaining the elastic modulus and density of the piezoelectric ceramic probe and calculating the longitudinal wave velocity of the piezoelectric ceramic probe; The number of layers and layer height of the multilayer material, the distance between the defect on the multilayer material and the center of the piezoelectric ceramic probe, and the distance between the center of the piezoelectric ceramic probe and the top layer of the multilayer material are obtained. Combined with the longitudinal wave velocity of the multilayer material and the longitudinal wave velocity of the piezoelectric ceramic probe, the required adjustment angles of the lateral variable angle module and the longitudinal variable angle module are determined.

9. The method for plane nondestructive testing of multilayer materials according to claim 8, characterized in that: The required adjustment angle of the lateral variable angle module is obtained according to the longitudinal wave velocity of the multilayer material, the longitudinal wave velocity of the piezoelectric ceramic probe, the distance between the defect on the multilayer material and the center of the piezoelectric ceramic probe in the y direction, and the distance between the center of the piezoelectric ceramic probe and the top layer of the multilayer material.

10. The planar nondestructive testing method of multilayer materials according to claim 8, characterized in that: The required adjustment angle of the lateral variable angle module is obtained according to the longitudinal wave velocity of the multilayer material, the longitudinal wave velocity of the piezoelectric ceramic probe, the distance between the defect on the multilayer material and the center of the piezoelectric ceramic probe in the x-direction, and the distance between the center of the piezoelectric ceramic probe and the top layer of the multilayer material.

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