Surface longitudinal wave generation method and ultrasonic wave detection method

Abstract

This invention discloses a method for generating surface longitudinal waves and an ultrasonic testing method, comprising: estimating the length of the non-diffusion zone and the half-diffusion angle corresponding to the ultrasonic longitudinal wave emitted by the longitudinal wave probe based on the probe diameter, longitudinal wave frequency, and longitudinal wave velocity of the selected longitudinal wave probe; selecting a triangular wedge whose middle side length is greater than the length of the non-diffusion zone and whose angle between the short and long sides matches the half-diffusion angle, and placing the long side of the wedge on the workpiece surface; fixing the longitudinal wave probe on the short side of the wedge and activating the probe to emit ultrasonic longitudinal waves perpendicularly to the short side of the wedge; because the length of the middle side of the wedge is greater than the length of the non-diffusion zone and the adjacent angle of the middle side is smaller than the half-diffusion angle of the ultrasonic longitudinal wave; the ultrasonic longitudinal wave only diffuses when it reaches the workpiece surface, thereby generating surface longitudinal waves on the workpiece surface and reducing ultrasonic longitudinal wave attenuation, thus increasing the propagation distance of the generated surface longitudinal waves.

Description

Technical Field

[0001] This invention relates to the field of measurement process technology using acoustic emission technology, specifically to a method for generating surface longitudinal waves and an ultrasonic detection method. Background Technology

[0002] Ultrasonic testing, as an important non-destructive testing technique, has been widely used in detecting structural defects, flaws, and stress in workpieces. Based on vibration similarity, ultrasonic waves can be classified into longitudinal waves, transverse waves, surface waves, and plate waves. Based on velocity, they can be further divided into faster waveforms (longitudinal waves, surface longitudinal waves, symmetrical Lamb waves) and slower waveforms (transverse waves, surface transverse waves, anti-symmetrical Lamb waves). Faster waveforms are far more sensitive than slower waveforms, better meeting the requirements for precision control.

[0003] When inspecting surface and near-surface defects of a workpiece, a longitudinal wave angle probe with an incident angle slightly greater than the first critical angle is typically used to generate surface longitudinal waves on and near the workpiece surface. However, the surface longitudinal waves generated by the longitudinal wave angle probe attenuate quickly, making it difficult to meet the measurement distance requirements. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a method for generating surface longitudinal waves and an ultrasonic detection method, which can extend the propagation distance of surface longitudinal waves to meet measurement distance requirements. The specific technical solution is as follows: In a first aspect, a method for generating surface longitudinal waves is provided, wherein in a first implementable manner of the first aspect, the method includes: Based on the probe diameter of the longitudinal wave straight probe, as well as the longitudinal wave frequency and longitudinal wave velocity emitted by the longitudinal wave straight probe, calculate the length of the unspread region and the half-spread angle of the longitudinal wave. Select a triangular wedge whose middle side length matches the length of the unspread region of the longitudinal wave, and whose angle between the short and long sides matches the half-spread angle, and place the long side of the wedge on the surface of the workpiece. The longitudinal wave probe is fixed on the short side of the wedge, and the longitudinal wave probe is activated to emit longitudinal waves vertically toward the short side to generate surface longitudinal waves on the workpiece.

[0005] In conjunction with the first possible implementation of the first aspect, in the second possible implementation of the first aspect, the material of the wedge is the same as the material of the workpiece.

[0006] In conjunction with the first implementable method of the first aspect, in the third implementable method of the first aspect, the outer surface of the wedge is smooth.

[0007] In conjunction with the first possible implementation of the first aspect, in the fourth possible implementation of the first aspect, the dimension of the short side of the wedge is larger than the probe diameter of the longitudinal wave straight probe.

[0008] In conjunction with the first implementable method of the first aspect, in the fifth implementable method of the first aspect, the long side surface of the wedge is placed on the workpiece surface, including: A coupling agent is applied to the contact surface between the wedge and the workpiece.

[0009] In conjunction with the first possible implementation of the first aspect, in the sixth possible implementation of the first aspect, fixing the longitudinal wave straight probe to the short side surface of the wedge includes: Coupling agent is applied to the contact surface between the wedge and the longitudinal wave straight probe.

[0010] Secondly, a method for generating surface longitudinal waves is provided, including: Place the long side of the selected triangular wedge on the workpiece surface; Based on the short side dimension and middle side length of the wedge, the probe diameter threshold and the longitudinal wave non-diffusion zone length threshold of the longitudinal wave straight probe are determined respectively. Based on the probe diameter threshold and the longitudinal wave non-diffusion region length threshold, a longitudinal wave straight probe with suitable probe diameter, longitudinal wave frequency and longitudinal wave velocity is selected. The longitudinal wave probe is fixed on the short side of the wedge, and the longitudinal wave probe is activated to emit longitudinal waves vertically toward the short side to generate surface longitudinal waves in the workpiece.

[0011] Thirdly, an ultrasonic testing method is provided, comprising: generating surface longitudinal waves within a workpiece using a surface longitudinal wave generation method as described in any of the first to sixth implementable methods of the first aspect.

[0012] Fourthly, an ultrasonic testing method is provided, comprising: generating surface longitudinal waves within a workpiece using the surface longitudinal wave generation method as described in the second aspect.

[0013] Beneficial Effects: The surface longitudinal wave generation method and ultrasonic detection method of this invention, using a set longitudinal wave straight probe, can generate ultrasonic longitudinal waves with frequencies and velocities adapted to the wedge. These generated ultrasonic longitudinal waves propagate along the wedge. Because the length of the middle side of the wedge is greater than the length of the un-diffused zone of the ultrasonic longitudinal wave, even after the ultrasonic longitudinal wave propagates beyond the un-diffused zone, it continues to propagate linearly along the wedge without diffusing until it reaches the contact surface between the wedge and the workpiece. This results in the ultrasonic longitudinal wave having a smaller area perpendicular to the propagation direction after exceeding the un-diffused zone than the theoretical area, thereby enhancing sound intensity and increasing the propagation distance of the generated surface longitudinal wave. Furthermore, the angle between the short and long sides is adapted to the half-diffuse angle, allowing the ultrasonic longitudinal wave to generate surface longitudinal waves on and near the surface of the workpiece after diffusing. Attached Figure Description

[0014] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the specific embodiments will be briefly described below. In all the drawings, the elements or parts are not necessarily drawn to scale.

[0015] Figure 1 This is a flowchart of a surface longitudinal wave generation method provided in an embodiment of the present invention; Figure 2 This is a flowchart of a surface longitudinal wave generation method provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the installation structure between the wedge, the workpiece, and the longitudinal wave probe in the surface longitudinal wave generation method provided by the present invention. Figure 4 This is a schematic diagram illustrating the generation principle of a surface longitudinal wave generation method provided in an embodiment of the present invention. Detailed Implementation

[0016] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0017] Example 1 like Figure 1 The flowchart shown illustrates a surface longitudinal wave generation method, which includes: Step 1: Calculate the length of the unspread region and the half-spread angle of the longitudinal wave based on the probe diameter of the longitudinal wave probe, as well as the longitudinal wave frequency and longitudinal wave velocity emitted by the longitudinal wave probe. Step 2: Select a triangular wedge whose middle side length matches the length of the unspread region of the longitudinal wave, and whose angle between the short and long sides matches the half-spread angle, and place the long side of the wedge on the surface of the workpiece. Step 3: Fix the longitudinal wave straight probe to the short side of the wedge block and start the longitudinal wave straight probe to emit longitudinal waves vertically to the short side to generate surface longitudinal waves on the workpiece.

[0018] Specifically, firstly, based on the probe diameter of the selected longitudinal wave probe, as well as the longitudinal wave frequency and velocity emitted by the probe, the length of the non-diffusion region and the half-diffusion angle of the ultrasonic longitudinal wave emitted by the probe can be estimated. The specific calculation formula is as follows: ; ; in, For the longitudinal wave frequency, For longitudinal wave velocity, The diameter of the probe. The length of the non-diffusion region. It is the half-diffusion angle.

[0019] Then, select a suitable wedge based on the length of the non-diffusion zone and the half-diffusion angle. The wedge can be a non-right-angled triangle, with the three sides of the triangle divided into the long side, the middle side, and the short side in descending order of side length. The wedge planes on which the long side, the middle side, and the short side are located are the long side plane, the middle side plane, and the short side plane, respectively.

[0020] The length of the middle side of the selected wedge is greater than the length of the non-diffusion region, and the angle between the middle side and the short side is... Less than 90 degrees, and the angle between the shorter and longer sides. satisfy .

[0021] like Figure 3 As shown, during testing, the long side of the wedge is placed on the surface of the workpiece to be tested. Finally, the selected longitudinal wave straight probe can be fixed on the short side of the wedge, and the probe is activated to emit ultrasonic longitudinal waves perpendicularly to the short side of the wedge. Figure 4 As shown, under normal circumstances, after the propagation distance of the ultrasonic longitudinal wave exceeds the length of the non-diffusion zone, the ultrasonic longitudinal wave will spread outwards at the half-diffusion angle, and the theoretical area perpendicular to the propagation direction of the ultrasonic longitudinal wave will increase.

[0022] However, since the length of the middle side of the wedge selected in this invention is greater than the length of the non-diffusion region, and the included angle between the middle side and the short side... The angle is less than 90 degrees, causing the theoretical diffusion boundary of the ultrasonic longitudinal wave emitted by the longitudinal wave probe to extend beyond the middle edge of the wedge. Therefore, when the propagation distance of the ultrasonic longitudinal wave within the wedge exceeds the length of the non-diffusion zone, the ultrasonic longitudinal wave will still propagate in a straight line along the middle edge of the wedge without diffusion, until it reaches the contact surface between the wedge and the workpiece surface, at which point it will continue to diffuse within the workpiece. This ensures that the area of ​​the ultrasonic longitudinal wave perpendicular to the propagation direction after exceeding the non-diffusion zone is smaller than the theoretical area. Based on the specific algorithm for sound intensity, this can be determined, resulting in an enhanced sound intensity and thus increasing the propagation distance of the generated surface longitudinal wave. The specific formula for calculating sound intensity is: ; For sound intensity, For ultrasonic longitudinal wave power, This is the area perpendicular to the direction of ultrasonic longitudinal wave propagation.

[0023] The half-diffusion angle of the ultrasonic longitudinal wave propagating within the wedge satisfies This results in the theoretical diffusion boundary line of the ultrasonic longitudinal wave after actual diffusion and propagation being located above the workpiece surface, which inevitably generates surface longitudinal waves on the workpiece surface.

[0024] In this embodiment, optionally, the wedge is made of the same material as the workpiece. Since ultrasonic longitudinal waves refract between the contact surfaces of objects made of different materials, it is necessary to select a wedge made of the same material as the workpiece to reduce ultrasonic longitudinal wave attenuation and increase the propagation distance of the generated surface longitudinal waves. For example, when inspecting steel plates, a steel wedge made of the same material as the steel plate should be selected. Furthermore, to reduce the secondary wave effect caused by sharp angles, a triangular wedge with the fewest sharp angles should be selected.

[0025] In this embodiment, optionally, the outer surface of the wedge is smooth. To ensure that the long side of the wedge is in close contact with the workpiece surface, the long side of the wedge, i.e., the contact surface between the wedge and the workpiece, can be polished smooth, and a conventional ultrasonic coupling agent can be coated on the contact surface between the wedge and the workpiece to reduce ultrasonic longitudinal wave attenuation and increase the surface longitudinal wave propagation distance. Furthermore, to further reduce ultrasonic longitudinal wave attenuation, an ultrasonic coupling agent can also be coated on the contact surface between the longitudinal wave probe and the wedge.

[0026] In this embodiment, optionally, the size of the short side of the wedge is larger than the probe diameter of the longitudinal wave straight probe.

[0027] Specifically, the size of the short side of the wedge can be larger than the probe diameter of the P-wave straight probe. A mounting hole that matches the diameter of the P-wave straight probe can be made on the short side, allowing the P-wave straight probe to be directly embedded into the mounting hole and fixed to the short side of the wedge.

[0028] Example 2 like Figure 2 The flowchart shown illustrates a surface longitudinal wave generation method, which includes: Step S1: Place the long side of the selected triangular wedge on the workpiece surface; Step S2: Determine the probe diameter threshold and the longitudinal wave non-diffusion zone length threshold of the longitudinal wave straight probe based on the short side surface size and middle side length of the wedge block, respectively. Step S3: Based on the probe diameter threshold and the longitudinal wave non-diffusion region length threshold, select a longitudinal wave straight probe that is compatible with the probe diameter, longitudinal wave frequency and longitudinal wave velocity. Step S4: Fix the longitudinal wave straight probe on the short side of the wedge and start the longitudinal wave straight probe to emit longitudinal waves vertically to the short side to generate surface longitudinal waves in the workpiece.

[0029] Specifically, first, a triangular wedge can be placed on the workpiece surface with its long side in contact with the surface. Then, the probe diameter threshold and the corresponding longitudinal wave non-diffusion zone length threshold can be determined based on the size of the wedge's short side. Next, a longitudinal wave straight probe with a diameter smaller than the determined probe diameter threshold and a non-diffusion zone length smaller than the longitudinal wave non-diffusion zone length threshold can be selected. Finally, the longitudinal wave straight probe can be fixed to the short side of the wedge and activated to emit ultrasonic longitudinal waves perpendicular to the short side of the wedge, thereby generating surface longitudinal waves on the workpiece surface.

[0030] An ultrasonic testing method includes: generating surface longitudinal waves within a workpiece using the surface longitudinal wave generation method described in Example 1.

[0031] An ultrasonic testing method includes: generating surface longitudinal waves within a workpiece using the surface longitudinal wave generation method described in Example 2.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for generating surface longitudinal waves, characterized in that, include: Based on the probe diameter of the longitudinal wave straight probe, as well as the longitudinal wave frequency and longitudinal wave velocity emitted by the longitudinal wave straight probe, calculate the length of the unspread region and the half-spread angle of the longitudinal wave. Select a triangular wedge whose middle side length matches the length of the unspread region of the longitudinal wave, and whose angle between the short and long sides matches the half-spread angle, and place the long side of the wedge on the surface of the workpiece. The longitudinal wave probe is fixed on the short side of the wedge, and the longitudinal wave probe is activated to emit longitudinal waves vertically toward the short side to generate surface longitudinal waves on the workpiece.

2. The surface longitudinal wave generation method according to claim 1, characterized in that, The wedge is made of the same material as the workpiece.

3. The surface longitudinal wave generation method according to claim 1, characterized in that, The outer surface of the wedge is smooth.

4. The surface longitudinal wave generation method according to claim 1, characterized in that, The size of the short side of the wedge is larger than the probe diameter of the longitudinal wave straight probe.

5. The surface longitudinal wave generation method according to claim 1, characterized in that, The long side of the wedge is placed on the workpiece surface, including: A coupling agent is applied to the contact surface between the wedge and the workpiece.

6. The surface longitudinal wave generation method according to claim 1, characterized in that, Fixing the longitudinal wave straight probe to the short side of the wedge includes: Coupling agent is applied to the contact surface between the wedge and the longitudinal wave straight probe.

7. A method for generating surface longitudinal waves, characterized in that, include: Place the long side of the selected triangular wedge on the workpiece surface; Based on the short side dimension and middle side length of the wedge, the probe diameter threshold and the longitudinal wave non-diffusion zone length threshold of the longitudinal wave straight probe are determined respectively. Based on the probe diameter threshold and the longitudinal wave non-diffusion region length threshold, a longitudinal wave straight probe with suitable probe diameter, longitudinal wave frequency and longitudinal wave velocity is selected. The longitudinal wave probe is fixed on the short side of the wedge, and the longitudinal wave probe is activated to emit longitudinal waves vertically toward the short side to generate surface longitudinal waves within the workpiece.

8. An ultrasonic testing method, characterized in that, include: Surface longitudinal waves are generated within the workpiece using the surface longitudinal wave generation method as described in any one of claims 1-6.

9. An ultrasonic testing method, characterized in that, include: The surface longitudinal wave generation method as described in claim 7 is used to generate surface longitudinal waves within the workpiece.

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