A selective excitation method and device of a lamb wave, an electronic device and a medium
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI AIRCRAFT MFG
- Filing Date
- 2026-04-16
- Publication Date
- 2026-06-12
AI Technical Summary
Existing technologies make it difficult to excite pure single-mode Lamb waves. The S0 mode is often accompanied by the A0 mode excitation. The S0 mode is easily mixed with higher-order modes. The S1 mode excitation efficiency is low and the zero group velocity effect is not fully utilized.
By acquiring the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test, the first and second scanning speeds are determined. The laser scanning speed is adjusted by using the control parameters of the rotating mirror to achieve the excitation of a single S0 mode and a mixed Lamb wave of higher-order modes, including the S1 mode zero group velocity Lamb wave.
It achieves non-contact excitation of pure single S0 mode Lamb wave and efficient excitation of S1 mode zero group velocity Lamb wave, suppresses low-order modes, and improves the excitation amplitude and signal-to-noise ratio of S1 mode, which is suitable for precision thin plate inspection.
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Figure CN122193403A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of nondestructive testing of thin plates and Lamb wave excitation technology, and particularly to a selective excitation method, apparatus, electronic device and medium for Lamb waves. Background Technology
[0002] Lamb waves are ultrasonic guided waves that propagate in thin plates. They are formed by the superposition of reflections from two free interfaces and are divided into symmetrical and antisymmetric modes. Different orders of modes can be specifically matched to different detection needs. By selectively exciting the modes, the accuracy and specificity of the detection can be improved.
[0003] In existing technologies, the number of excited modes can generally be reduced by controlling frequency-thickness product, selecting transducers with special structures, using symmetrical or antisymmetric excitation methods, and utilizing pulsed laser side-symmetric excitation.
[0004] However, while existing technologies can reduce the number of excited modes, they cannot achieve the excitation of a pure single-mode Lamb wave. The S0 mode is often excited simultaneously with the A0 mode, and the S0 mode is easily mixed with higher-order modes. At the same time, the excitation efficiency for higher-order S1 modes is low, and the unique zero group velocity effect of the S1 mode cannot be fully utilized. Summary of the Invention
[0005] This invention provides a selective excitation method, apparatus, electronic device, and medium for Lamb waves, which can achieve single excitation of the S0 mode and efficient excitation of the S1 mode zero-group velocity Lamb wave. It effectively eliminates low-order modes in the mixed Lamb wave of higher-order modes, and the excitation amplitude and signal-to-noise ratio of the S1 mode are high, which can effectively utilize the unique zero-group velocity effect of the S1 mode.
[0006] According to one aspect of the present invention, a method for selectively exciting Lamb waves is provided, comprising: Obtain the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test; The first scanning speed is determined based on the surface wave velocity and the transverse wave velocity, and the second scanning speed is determined based on the phase velocity corresponding to the S1 mode at the zero group velocity point. Based on the first scanning speed and the second scanning speed, determine the first control parameter and the second control parameter of the rotating mirror; During the process of emitting a laser onto the surface of the thin plate under test, the rotating mirror is adjusted according to the first control parameter and the second control parameter respectively to obtain a single S0 mode Lamb wave and a higher-order mode mixed Lamb wave; wherein, the higher-order mode mixed Lamb wave includes an S1 mode zero group velocity Lamb wave.
[0007] According to another aspect of the present invention, a selective excitation device for a Lamb wave is provided, comprising: The reference velocity acquisition module is used to acquire the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test. The scanning speed determination module is used to determine a first scanning speed based on the surface wave velocity and the transverse wave velocity, and to determine a second scanning speed based on the phase velocity corresponding to the S1 mode at the zero group velocity point. The control parameter determination module is used to determine the first control parameter and the second control parameter of the rotating mirror based on the first scanning speed and the second scanning speed. The Lamb wave acquisition module is used to adjust the rotating mirror according to the first control parameter and the second control parameter respectively during the process of emitting laser to the surface of the thin plate under test, so as to obtain a single S0 mode Lamb wave and a higher-order mode mixed Lamb wave; wherein, the higher-order mode mixed Lamb wave includes an S1 mode zero group velocity Lamb wave.
[0008] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program that can be executed by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the selective excitation method of the Lamb wave according to any embodiment of the present invention.
[0009] According to another aspect of the present invention, a computer-readable storage medium is provided, the computer-readable storage medium storing computer instructions for causing a processor to execute and implement the selective excitation method of the Lamb wave according to any embodiment of the present invention.
[0010] The technical solution of this invention obtains the surface wave velocity, transverse wave velocity, and phase velocity corresponding to the S1 mode at the zero group velocity point of the thin plate under test, determines the first scanning speed and the second scanning speed, and determines the first control parameters and the second control parameters of the rotating mirror based on the first scanning speed and the second scanning speed. During the laser emission onto the surface of the thin plate under test, the rotating mirror is adjusted according to the first control parameters and the second control parameters respectively, to obtain a single S0 mode Lamb wave and a mixed higher-order mode Lamb wave. This allows for the excitation of Lamb waves using a fully optical method, without any interference during the excitation process. It requires contact with the surface of the thin plate under test and does not require a coupling agent, enabling the detection of precision thin plate components. It overcomes the limitations of traditional transducer contact excitation scenarios, has a wide range of applications, and can achieve selective excitation of a single S0 mode Lamb wave. It solves the problem of S0 mode mixed with A0 mode or higher-order modes in existing technologies, and can also achieve effective excitation of S1 mode zero group velocity Lamb wave. While suppressing low-order modes, it significantly improves the excitation amplitude and signal-to-noise ratio of S1 mode, solves the problem that traditional methods cannot effectively extract S1 zero group velocity waves, and effectively utilizes the unique zero group velocity effect of S1 mode.
[0011] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description
[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0013] Figure 1 This is a flowchart of a selective excitation method for Lamb waves according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of a phase velocity dispersion curve provided by an embodiment of the present invention; Figure 3 This is a flowchart of another selective excitation method for Lamb waves provided in Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of a single S0 mode Lamb wave provided according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a high-order mode hybrid Lamb wave provided according to an embodiment of the present invention; Figure 6This is a schematic diagram of the structure of a selective excitation device for Lamb waves according to Embodiment 3 of the present invention; Figure 7 This is a schematic diagram of the structure of an electronic device that implements the selective excitation method of Lamb waves according to embodiments of the present invention. Detailed Implementation
[0014] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0015] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0016] Example 1 Figure 1 This is a flowchart of a selective excitation method for a Lamb wave according to Embodiment 1 of the present invention. This embodiment is applicable to the situation of exciting a single S0 mode Lamb wave and efficiently exciting an S1 mode Lamb wave. This method can be executed by a selective excitation device for a Lamb wave, which can be implemented in hardware and / or software, and is generally configured in a computer or processor with data processing capabilities. Figure 1 As shown, the method includes: S110: Obtain the surface wave velocity, transverse wave velocity, and phase velocity of mode S1 at the zero group velocity point of the thin plate under test.
[0017] Optionally, a Lamb wave is an elastic guided wave formed by the repeated reflection and superposition of longitudinal and transverse waves on the upper and lower surfaces of a thin plate structure. It can be divided into symmetrical modes (such as S0, S1, S2, etc.) and antisymmetric modes (such as A0, A1, A2, etc.) according to the vibration symmetry. Among them, S0 and A0 modes are low-order modes, while S1, A1, S2, A2, etc. are high-order modes.
[0018] Optionally, surface wave velocity is the propagation speed of an elastic wave propagating along the surface of a solid; transverse wave velocity is the propagation speed of a transverse wave in a solid; phase velocity is the speed at which the phase of a Lamb wave vibration moves along the propagation direction; group velocity is the propagation speed of the Lamb wave energy packet; zero group velocity refers to a special state in which energy does not propagate and only resonates locally at the excitation point. At the zero group velocity point, the group velocity is 0, but the phase velocity and wave number are not 0.
[0019] Optionally, the surface wave velocity, transverse wave velocity, and phase velocity corresponding to the zero group velocity point of the S1 mode can be obtained by calculation or identified from the phase velocity dispersion curve.
[0020] Optionally, the phase velocity dispersion curve can reflect the variation law of phase velocity of different modes of Lamb wave with frequency-thickness product. The horizontal axis of the phase velocity dispersion curve is the frequency-thickness product, that is, the product of frequency and thickness, and the vertical axis is the phase velocity. The phase velocity dispersion curve can be automatically generated by finite element analysis software according to the material properties of the thin plate to be tested, or it can be established through multiple experimental measurements.
[0021] S120. Determine the first scanning speed based on the surface wave velocity and the transverse wave velocity, and determine the second scanning speed based on the phase velocity corresponding to the zero group velocity point of the S1 mode.
[0022] Optionally, the scanning speed is the uniform movement speed of the laser spot on the surface of the thin plate after being controlled by the rotating mirror. By adjusting the scanning speed, selective excitation of a specified mode of Lamb wave can be achieved.
[0023] Optionally, the first scanning speed can be any speed within the speed range of the surface wave velocity and the transverse wave velocity. The first scanning speed is used for selective excitation of a single S0 mode Lamb wave. For example, the surface wave velocity can be expressed as C... R This indicates that the transverse wave velocity is expressed in terms of C. T This indicates that the transverse wave velocity is higher than the surface wave velocity; therefore, the velocity range formed by the surface wave velocity and the transverse wave velocity is [C]. R C T If the first scan speed is represented by V1, then C R ≤V1≤C T .
[0024] Optionally, the second scan rate can be equal to the phase velocity corresponding to the S1 mode at the zero group velocity point. The second scan rate is used for selective excitation of higher-order mode mixed Lamb waves containing the zero group velocity Lamb wave of the S1 mode. If the phase velocity corresponding to the S1 mode at the zero group velocity point is expressed as C... ZGV Let the second scan speed be denoted by V2, then V2 = C ZGV .
[0025] The determination of a first scanning speed based on the surface wave velocity and the transverse wave velocity, and the determination of a second scanning speed based on the phase velocity corresponding to the S1 mode at the zero group velocity point, may include: Based on the surface wave velocity and the transverse wave velocity, a velocity range is determined, and a target velocity within the velocity range is determined as the first scanning velocity. The phase velocity corresponding to the zero group velocity point of the S1 mode is taken as the second scan velocity.
[0026] Optionally, the minimum value of the velocity range is the surface wave velocity, and the maximum value is the transverse wave velocity. Any velocity within the velocity range can be selected as the target velocity, or an integer value can be selected as the target velocity. Alternatively, the velocity of stable excitation can be determined as the target velocity. The velocity of stable excitation can be a velocity value that does not easily deviate from the matching conditions due to working conditions, slight material fluctuations, or laser scanning jitter. It can be determined through experiments or calculations.
[0027] Figure 2 This is a schematic diagram of an optional phase velocity dispersion curve. (Example) Figure 2 As shown, Figure 2 The phase velocity dispersion curves depict the relationship between the phase velocity and the frequency-thickness product of the Lamb waves in modes S0, A0, S1, and A1, respectively. Figure 2 In the graph, the horizontal axis fd represents the frequency-thickness product, where MHz is the unit of frequency (megahertz) and mm is the unit of thickness (millimeters). The vertical axis Cp represents the phase velocity, where km / s is the unit of phase velocity (kilometers per second). Figure 2 C in R For surface wave sound velocity, C T For the transverse wave velocity, C ZGV Let be the phase velocity corresponding to the zero group velocity point of the S1 mode. At the zero group velocity point of the S1 mode, the curvature of the phase velocity dispersion curve of the S1 mode changes from positive to negative.
[0028] Furthermore, as the frequency-thickness product approaches infinity, the phase velocities of the S0 and A0 modes approach the surface wave velocity C. R The phase velocities of the S1 and A1 modes approach the transverse wave velocity C. T ,exist Figure 2 The phase velocities of the other higher-order modes, not shown in the figure, also approach the transverse wave velocity C. T For example, S2, A2, etc.
[0029] It is understandable that, since the phase velocity of the A0 mode is increasing, when the frequency-thickness product approaches infinity, the A0 mode reaches its maximum phase velocity without exceeding the surface wave velocity. However, the phase velocities of the S0 mode and higher-order modes are decreasing. When the frequency-thickness product approaches infinity, the S0 mode reaches its minimum phase velocity without exceeding the surface wave velocity, and the higher-order modes reach their minimum phase velocities but are higher than the transverse wave velocity. Therefore, by exciting a Lamb wave within the velocity range formed by the surface wave velocity and the transverse wave velocity, a single S0 mode Lamb wave can be obtained.
[0030] It is understandable that the zero group velocity effect of the S1 mode can be used for high-precision thickness measurement. However, in the existing technology, the amplitude of the low-order mode Lamb wave is very high, and it is difficult to obtain usable high-order mode Lamb waves by traditional excitation methods. Signal analysis of the S1 mode is also difficult, and the unique zero group velocity effect of the S1 mode is difficult to utilize effectively. However, this application utilizes the phase velocity corresponding to the zero group velocity point of the S1 mode to excite the Lamb wave. The phase distribution of the excitation space applied by the laser to the thin plate is completely matched with the intrinsic phase distribution of the S1 mode, resulting in phase resonance enhancement, which enables the S1 mode to obtain maximum energy coupling. At the same time, it is severely mismatched with the phase velocity of the low-order mode, and the low-order mode is eliminated, thereby achieving efficient excitation of the S1 mode Lamb wave.
[0031] S130. Determine the first control parameters and the second control parameters of the rotating mirror based on the first scanning speed and the second scanning speed.
[0032] Optionally, the laser source can be controlled to emit a continuous laser beam onto the thin plate under test. The rotating mirror is located in the optical path of the laser source. By adjusting the rotation speed of the rotating mirror and the projection distance from the rotating mirror to the surface of the thin plate under test, the scanning speed of the laser on the surface of the thin plate under test can be adjusted.
[0033] Optionally, the control parameters include rotation speed and distance. Rotation speed can refer to the rotation speed of the rotating mirror, and distance can refer to the projection distance from the rotating mirror to the surface of the thin plate to be measured.
[0034] Optionally, the first control parameter can be used to excite a single S0 mode Lamb wave without clutter interference, and the second control parameter can be used to excite a high-order mode mixed Lamb wave with S1 zero-group velocity wave as the main component and elimination of low-order modes.
[0035] Determining the first control parameters and the second control parameters of the rotating mirror based on the first scanning speed and the second scanning speed may include: Based on the first scanning speed, the first rotation speed and the first distance of the rotating mirror are determined, and the first rotation speed and the first distance are used as the first control parameters of the rotating mirror; Based on the first distance and the second scanning speed, a second rotation speed is determined, and the second rotation speed and the first distance are used as the second control parameters of the rotating mirror.
[0036] Optionally, the first control parameter includes a first rotational speed and a first distance, and the second control parameter includes a second rotational speed and a first distance.
[0037] Optionally, based on the first scanning speed, the preset spot diameter, and the optical path geometry, the first rotation speed and the first distance can be calculated. After determining the first distance, the first distance is fixed, and based on the second scanning speed, the preset spot diameter, and the optical path geometry, the second rotation speed can be calculated.
[0038] Optionally, after obtaining the first and second scanning speeds, the control parameters can be calculated by substituting the actual positional relationship between the laser source and the thin plates into the standard calculation formula, or the first and second scanning speeds can be input into the simulation software to directly obtain the control parameters.
[0039] S140. During the process of emitting laser light onto the surface of the thin plate to be tested, the rotating mirror is adjusted according to the first control parameter and the second control parameter respectively to obtain a single S0 mode Lamb wave and a higher-order mode mixed Lamb wave.
[0040] Among them, the higher-order mode mixed Lamb wave includes the S1 mode zero group velocity Lamb wave.
[0041] Optionally, the S1 mode zero group velocity Lamb wave refers to a special guided wave in which the group velocity of the S1 higher-order symmetric Lamb wave is 0 and the energy is locally resonant under a specific frequency thick accumulation.
[0042] Optionally, a continuous laser is used to perform non-contact laser scanning on the surface of the thin plate to be measured. During laser emission, a rotating mirror is driven according to the first control parameter to make the laser spot form a uniform scanning speed on the plate surface and reach the first scanning speed, thereby exciting a single S0 mode Lamb wave without clutter interference. Then, the output state of the laser source and the projection distance from the rotating mirror to the surface of the thin plate to be measured are kept unchanged. The rotation speed of the rotating mirror is increased according to the second control parameter to make the spot scanning speed reach the second scanning speed, thereby exciting a high-order mode mixed Lamb wave. The high-order mode mixed Lamb wave includes an S1 mode zero group velocity Lamb wave that can be used for high-precision thickness measurement.
[0043] Optionally, a higher-order mode mixed Lamb wave refers to a complex waveform formed by simultaneously exciting multiple higher-order modes superimposed together. However, in the higher-order mode mixed Lamb wave of this embodiment of the invention, the S1 zero-group velocity wave is the main body, which has a high signal-to-noise ratio, and the lower-order modes are significantly suppressed.
[0044] Optionally, this invention uses a combination of laser-triggered Lamb wave and scanning speed limitation to ensure that only a single S0 mode Lamb wave is excited, overcoming the problem that traditional transducers or laser side excitation cannot obtain a pure single mode and that the S0 mode is easily mixed with higher-order modes.
[0045] During the laser emission onto the surface of the thin plate under test, the rotating mirror is adjusted according to the first control parameter and the second control parameter to obtain a single S0 mode Lamb wave and a higher-order mode mixed Lamb wave, which may include: When a laser is emitted onto the surface of the thin plate under test, the rotating mirror is adjusted according to the first control parameter so that the moving speed of the laser source on the surface of the thin plate under test reaches the first scanning speed, and the received time domain signal is subjected to Fourier transform to obtain a single S0 mode Lamb wave. A laser is continuously emitted onto the surface of the thin plate under test. The rotating mirror is fixed at the first distance, and the rotation speed of the rotating mirror is increased from the first rotation speed to the second rotation speed so that the moving speed of the laser source on the surface of the thin plate under test reaches the second scanning speed. The received time-domain signal is then subjected to Fourier transform to obtain a higher-order mode mixed Lamb wave.
[0046] Optionally, when a laser is emitted onto the surface of the thin plate to be tested, the rotating mirror is driven according to the first control parameter, which can stabilize the scanning speed of the laser spot at the first scanning speed, realize phase velocity matching excitation, suppress A0 and all higher-order modes, and obtain a single S0 mode Lamb wave after performing a Fourier transform on the received signal.
[0047] Optionally, while keeping the laser power, spot size, and projection distance unchanged, the rotation speed of the rotating mirror is increased to the second rotation speed, so that the spot scanning speed accurately reaches the second scanning speed. At this time, the low-order is eliminated, the S1 mode zero-group velocity wave is efficiently excited, and after performing a Fourier transform on the received signal, a high-order mixed Lamb wave with the S1 zero-group velocity wave as the main component is obtained.
[0048] In addition to obtaining the single S0 mode Lamb wave and the higher-order mode mixed Lamb wave, it may also include: In the higher-order mode mixed Lamb wave, the S1 mode zero group velocity Lamb wave is extracted, and the thickness of the thin plate to be measured is determined based on the S1 mode zero group velocity Lamb wave.
[0049] Optionally, the high-order mixed Lamb wave can be filtered to remove residual high-order interference, extract the pure S1 mode zero group velocity Lamb wave, and based on the characteristic resonance frequency of the S1 mode zero group velocity Lamb wave and the constant relationship between the frequency-thickness product, the high-precision thickness value of the thin plate under test can be calculated by inversion, realizing the thickness measurement and thickness uniformity detection from micrometer to nanometer level.
[0050] Optionally, since the signal-to-noise ratio of the S1 mode zero-group velocity Lamb wave in the high-order mode mixed Lamb wave is high in this embodiment, filtering can be omitted, and the effective S1 mode signal in the high-order mode mixed Lamb wave can be directly used for thickness measurement.
[0051] The technical solution of this invention obtains the surface wave velocity, transverse wave velocity, and phase velocity corresponding to the S1 mode at the zero group velocity point of the thin plate under test, determines the first scanning speed and the second scanning speed, and determines the first control parameters and the second control parameters of the rotating mirror based on the first scanning speed and the second scanning speed. During the laser emission onto the surface of the thin plate under test, the rotating mirror is adjusted according to the first control parameters and the second control parameters respectively, to obtain a single S0 mode Lamb wave and a mixed higher-order mode Lamb wave. This allows for the excitation of Lamb waves using a fully optical method, without any interference during the excitation process. It requires contact with the surface of the thin plate under test and does not require a coupling agent, enabling the detection of precision thin plate components. It overcomes the limitations of traditional transducer contact excitation scenarios, has a wide range of applications, and can achieve selective excitation of a single S0 mode Lamb wave. It solves the problem of S0 mode mixed with A0 mode or higher-order modes in existing technologies, and can also achieve effective excitation of S1 mode zero group velocity Lamb wave. While suppressing low-order modes, it significantly improves the excitation amplitude and signal-to-noise ratio of S1 mode, solves the problem that traditional methods cannot effectively extract S1 zero group velocity waves, and effectively utilizes the unique zero group velocity effect of S1 mode.
[0052] Example 2 Figure 3 This is a flowchart of a selective excitation method for Lamb waves provided in Embodiment 2 of the present invention. This embodiment, based on the above embodiments, specifically illustrates the selective excitation method for Lamb waves. Figure 3 As shown, the method includes: S210: Obtain the surface wave velocity, transverse wave velocity, and phase velocity of mode S1 at the zero group velocity point of the thin plate under test.
[0053] The acquisition of the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test may include any of the following: The material properties of the thin plate under test are determined, and based on these properties, the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point are calculated. The phase velocity dispersion curve of the Lamb wave propagation in the thin plate under test is generated, and the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test are identified based on the phase velocity dispersion curve.
[0054] Optionally, the material property can refer to the material category of the sheet to be tested, such as gold, silver, aluminum, etc.
[0055] Optionally, the mechanical properties of the sheet to be tested can be determined based on the material properties. The mechanical properties may include at least the material elastic constant, material density, and material Poisson's ratio.
[0056] Optionally, calculating the surface wave velocity and transverse wave velocity of the thin plate under test based on the material properties may include: Based on the material properties, determine the material elastic constant, material density, and material Poisson's ratio of the thin plate to be tested; Based on the material's elastic constants and density, the transverse wave velocity of the thin plate under test is calculated, and based on the transverse wave velocity and the material's Poisson's ratio, the surface wave velocity is calculated.
[0057] Optional, it can be based on the formula The transverse wave velocity was calculated, where C T Let μ be the transverse wave velocity, μ be the material elastic constant, and ρ be the material density.
[0058] Optional, it can be based on the formula The surface wave velocity was calculated, where C T For the transverse wave velocity, C R Let v be the surface wave velocity, and v be the material's Poisson's ratio.
[0059] Optionally, the material properties of the thin plate can be input into the finite element analysis software, and the phase velocity corresponding to the S1 mode at the zero group velocity point can be quickly calculated through software analysis.
[0060] Optionally, the phase velocity dispersion curve of Lamb wave propagation in the thin plate under test can also be determined based on the material properties. The material properties are input into the finite element analysis software, and the finite element analysis software can directly calculate the phase velocity dispersion curve of Lamb wave propagation in the thin plate under test based on the mechanical properties corresponding to the material properties.
[0061] The process of generating the phase velocity dispersion curve of the Lamb wave propagation in the thin plate under test, and identifying the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test based on the phase velocity dispersion curve, may include: Lamb waves are excited on the surface of the thin plate under test, and time-domain vibration signals of the Lamb waves are received at multiple equally spaced detection points. A two-dimensional Fourier transform is performed on the received time-domain vibration signal to generate the phase velocity dispersion curve of the Lamb wave propagation in the thin plate under test. Based on the phase velocity dispersion curve, the phase velocity limit values of the low-order mode and the high-order mode are identified when the frequency-thickness product tends to infinity. The phase velocity limit value of the low-order mode is taken as the surface wave velocity, and the phase velocity limit value of the high-order mode is taken as the transverse wave velocity. Based on the phase velocity dispersion curve, the curvature change point of the S1 mode is identified, and the phase velocity value corresponding to the curvature change point is taken as the phase velocity of the S1 mode at the zero group velocity point.
[0062] Optionally, the phase velocity dispersion curve of the Lamb wave propagation in the thin plate under test can be obtained by exciting Lamb waves at multiple points on the surface of the thin plate under test.
[0063] Optionally, Lamb waves are excited at multiple points on the surface of the thin plate under test, and multiple equally spaced detection points are arranged along the propagation path to synchronously collect time-domain vibration signals. The multi-channel time-domain signals are then processed by two-dimensional Fourier transform to reconstruct the phase velocity dispersion curve of the thin plate under test.
[0064] Optionally, on the dispersion curve, extract the characteristic values of the frequency-thickness product that tends to infinity. The phase velocity limit of the low-order mode is the surface wave velocity, and the phase velocity limit of the high-order mode is the transverse wave velocity. Locate the curvature change point of the S1 mode on the dispersion curve. This point is the zero group velocity point of the S1 mode, and its corresponding phase velocity is the phase velocity of the S1 mode at the zero group velocity point.
[0065] S220. Determine the velocity range based on the surface wave velocity and the transverse wave velocity, and determine the target velocity within the velocity range as the first scanning velocity.
[0066] S230, take the phase velocity corresponding to the zero group velocity point of mode S1 as the second scan velocity.
[0067] S240. Based on the first scanning speed, determine the first rotation speed and the first distance of the rotating mirror, and use the first rotation speed and the first distance as the first control parameters of the rotating mirror.
[0068] S250. Determine the second rotation speed based on the first distance and the second scanning speed, and use the second rotation speed and the first distance as the second control parameters for the rotating mirror.
[0069] S260. When a laser is emitted onto the surface of the thin plate to be tested, the rotating mirror is adjusted according to the first control parameter so that the moving speed of the laser source on the surface of the thin plate to be tested reaches the first scanning speed, and the received time-domain signal is subjected to Fourier transform to obtain a single S0 mode Lamb wave.
[0070] Figure 4 A schematic diagram of an optional single S0 mode Lamb wave, as shown below. Figure 4 As shown, the left side is the time-domain signal image of a single S0 mode, and the right side is the Lamb wave image of a single S0 mode obtained after Fourier transform, which is a frequency-domain signal that can be used for subsequent detection. In the left image, the horizontal axis is the delay time in microseconds and the vertical axis is the normalized amplitude. In the right image, the horizontal axis is the frequency in megahertz and the vertical axis is the normalized amplitude. According to the right image, it can be seen that the single S0 mode Lamb wave in the frequency domain image has only one peak and does not contain other modes.
[0071] Optionally, Lamb waves can be excited by all-optical non-contact laser without the need for coupling agent, making it suitable for extreme scenarios such as thin aerospace plates, high-temperature components, brittle materials, and precision wafers.
[0072] S270. Continuously emit laser light onto the surface of the thin plate under test, fix the rotating mirror at a first distance, and increase the rotation speed of the rotating mirror from the first rotation speed to the second rotation speed so that the laser source moves at the second scanning speed on the surface of the thin plate under test, and perform Fourier transform on the received time domain signal to obtain the high-order mode mixed Lamb wave.
[0073] Optionally, by fixing the first distance and only adjusting the rotation speed of the rotating mirror, the engineering implementation difficulty can be effectively reduced, the stability is strong, and online high-speed detection can be supported.
[0074] Figure 5 A schematic diagram of an optional higher-order mode hybrid Lamb wave, as shown below. Figure 5 As shown, the left side is the time-domain signal of the higher-order mode mixed Lamb wave, and the right side is the higher-order mode mixed Lamb wave image obtained after Fourier transform, which is a frequency-domain signal that can be used for subsequent detection. In the left image, the horizontal axis is the delay time in microseconds and the vertical axis is the amplitude. In the right image, the horizontal axis is the frequency in Hertz and the vertical axis is the amplitude. According to the right image, there are multiple peaks in the frequency domain image, and each peak belongs to a different higher-order mode. However, the peak with the highest amplitude belongs to the S1 mode and is significantly higher than the peak values of other modes.
[0075] The technical solution of this invention can obtain the surface wave velocity, transverse wave velocity, and phase velocity corresponding to the zero group velocity point of the S1 mode by calculating and generating phase velocity dispersion curves. It can be widely applied to thin plates with different material properties and can be applied to different excitation scenarios. Whether it is a commonly used material or a newly developed material, it can selectively excite a single S0 mode Lamb wave or efficiently excite an S1 mode zero group velocity Lamb wave.
[0076] Example 3 Figure 6 This is a schematic diagram of a selective excitation device for Lamb waves provided in Embodiment 3 of the present invention. Figure 6 As shown, the device includes: a reference speed acquisition module 310, a scan speed determination module 320, a control parameter determination module 330, and a Lamb wave acquisition module 340.
[0077] The reference velocity acquisition module 310 is used to acquire the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test.
[0078] The scanning speed determination module 320 is used to determine a first scanning speed based on the surface wave velocity and the transverse wave velocity, and to determine a second scanning speed based on the phase velocity corresponding to the zero group velocity point of the S1 mode.
[0079] The control parameter determination module 330 is used to determine the first control parameter and the second control parameter of the rotating mirror based on the first scanning speed and the second scanning speed.
[0080] The Lamb wave acquisition module 340 is used to adjust the rotating mirror according to the first control parameter and the second control parameter respectively during the process of emitting laser to the surface of the thin plate to be tested, so as to acquire a single S0 mode Lamb wave and a higher-order mode mixed Lamb wave; wherein, the higher-order mode mixed Lamb wave includes an S1 mode zero group velocity Lamb wave.
[0081] The technical solution of this invention obtains the surface wave velocity, transverse wave velocity, and phase velocity corresponding to the S1 mode at the zero group velocity point of the thin plate under test, determines the first scanning speed and the second scanning speed, and determines the first control parameters and the second control parameters of the rotating mirror based on the first scanning speed and the second scanning speed. During the laser emission onto the surface of the thin plate under test, the rotating mirror is adjusted according to the first control parameters and the second control parameters respectively, to obtain a single S0 mode Lamb wave and a mixed higher-order mode Lamb wave. This allows for the excitation of Lamb waves using a fully optical method, without any interference during the excitation process. It requires contact with the surface of the thin plate under test and does not require a coupling agent, enabling the detection of precision thin plate components. It overcomes the limitations of traditional transducer contact excitation scenarios, has a wide range of applications, and can achieve selective excitation of a single S0 mode Lamb wave. It solves the problem of S0 mode mixed with A0 mode or higher-order modes in existing technologies, and can also achieve effective excitation of S1 mode zero group velocity Lamb wave. While suppressing low-order modes, it significantly improves the excitation amplitude and signal-to-noise ratio of S1 mode, solves the problem that traditional methods cannot effectively extract S1 zero group velocity waves, and effectively utilizes the unique zero group velocity effect of S1 mode.
[0082] Based on the above embodiments, the reference speed acquisition module 310 may include any of the following units: A reference velocity calculation unit is used to determine the material properties of the thin plate under test, and based on the material properties, calculate the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test; and The reference velocity identification unit is used to generate the phase velocity dispersion curve of the Lamb wave propagation in the thin plate under test, and to identify the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test based on the phase velocity dispersion curve.
[0083] Based on the above embodiments, the reference speed identification unit can be specifically used for: Lamb waves are excited on the surface of the thin plate under test, and time-domain vibration signals of the Lamb waves are received at multiple equally spaced detection points. A two-dimensional Fourier transform is performed on the received time-domain vibration signal to generate the phase velocity dispersion curve of the Lamb wave propagation in the thin plate under test. Based on the phase velocity dispersion curve, the phase velocity limit values of the low-order mode and the high-order mode are identified when the frequency-thickness product tends to infinity. The phase velocity limit value of the low-order mode is taken as the surface wave velocity, and the phase velocity limit value of the high-order mode is taken as the transverse wave velocity. Based on the phase velocity dispersion curve, the curvature change point of the S1 mode is identified, and the phase velocity value corresponding to the curvature change point is taken as the phase velocity of the S1 mode at the zero group velocity point.
[0084] Based on the above embodiments, the scanning speed determination module 320 can be specifically used for: Based on the surface wave velocity and the transverse wave velocity, a velocity range is determined, and a target velocity within the velocity range is determined as the first scanning velocity. The phase velocity corresponding to the zero group velocity point of the S1 mode is taken as the second scan velocity.
[0085] Based on the above embodiments, the control parameter determination module 330 can be specifically used for: Based on the first scanning speed, the first rotation speed and the first distance of the rotating mirror are determined, and the first rotation speed and the first distance are used as the first control parameters of the rotating mirror; Based on the first distance and the second scanning speed, a second rotation speed is determined, and the second rotation speed and the first distance are used as the second control parameters of the rotating mirror.
[0086] Based on the above embodiments, the Lamb wave acquisition module 340 can be specifically used for: When a laser is emitted onto the surface of the thin plate under test, the rotating mirror is adjusted according to the first control parameter so that the moving speed of the laser source on the surface of the thin plate under test reaches the first scanning speed, and the received time domain signal is subjected to Fourier transform to obtain a single S0 mode Lamb wave. A laser is continuously emitted onto the surface of the thin plate under test. The rotating mirror is fixed at the first distance, and the rotation speed of the rotating mirror is increased from the first rotation speed to the second rotation speed so that the moving speed of the laser source on the surface of the thin plate under test reaches the second scanning speed. The received time-domain signal is then subjected to Fourier transform to obtain a higher-order mode mixed Lamb wave.
[0087] Based on the above embodiments, a thickness measurement module may also be included, for: In the higher-order mode mixed Lamb wave, the S1 mode zero group velocity Lamb wave is extracted, and the thickness of the thin plate to be measured is determined based on the S1 mode zero group velocity Lamb wave.
[0088] The selective excitation device for Lamb waves provided in the embodiments of the present invention can execute the selective excitation method for Lamb waves provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the method.
[0089] Example 4 Figure 7 A schematic diagram of an electronic device 10, which can be used to implement embodiments of the present invention, is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (e.g., helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.
[0090] like Figure 7 As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded from storage unit 18 into the RAM 13. The RAM 13 can also store various programs and data required for the operation of the electronic device 10. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.
[0091] Multiple components in electronic device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.
[0092] Processor 11 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, central processing unit (CPU), graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, digital signal processors (DSPs), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as the selective excitation method of Lamb waves described in the embodiments of the present invention. That is: Obtain the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test; The first scanning speed is determined based on the surface wave velocity and the transverse wave velocity, and the second scanning speed is determined based on the phase velocity corresponding to the S1 mode at the zero group velocity point. Based on the first scanning speed and the second scanning speed, determine the first control parameter and the second control parameter of the rotating mirror; During the process of emitting a laser onto the surface of the thin plate under test, the rotating mirror is adjusted according to the first control parameter and the second control parameter respectively to obtain a single S0 mode Lamb wave and a higher-order mode mixed Lamb wave; wherein, the higher-order mode mixed Lamb wave includes an S1 mode zero group velocity Lamb wave.
[0093] In some embodiments, the selective excitation method of the Lamb wave can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or mounted on electronic device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the selective excitation method of the Lamb wave described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform the selective excitation method of the Lamb wave by any other suitable means (e.g., by means of firmware).
[0094] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip (SoCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.
[0095] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.
[0096] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.
[0097] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).
[0098] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or middleware components (e.g., application servers), or frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.
[0099] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.
[0100] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.
[0101] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.
Claims
1. A method for selectively excitation of Lamb waves, characterized in that, include: Obtain the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test; The first scanning speed is determined based on the surface wave velocity and the transverse wave velocity, and the second scanning speed is determined based on the phase velocity corresponding to the S1 mode at the zero group velocity point. Based on the first scanning speed and the second scanning speed, determine the first control parameter and the second control parameter of the rotating mirror; During the process of emitting a laser onto the surface of the thin plate under test, the rotating mirror is adjusted according to the first control parameter and the second control parameter respectively to obtain a single S0 mode Lamb wave and a higher-order mode mixed Lamb wave; wherein, the higher-order mode mixed Lamb wave includes an S1 mode zero group velocity Lamb wave.
2. The method according to claim 1, characterized in that, Obtain the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test, including any one of the following: The material properties of the thin plate to be tested are determined, and the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point are calculated based on the material properties. as well as The phase velocity dispersion curve of the Lamb wave propagation in the thin plate under test is generated, and the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test are identified based on the phase velocity dispersion curve.
3. The method according to claim 2, characterized in that, Generate the phase velocity dispersion curve of the Lamb wave propagation in the thin plate under test, and based on the phase velocity dispersion curve, identify the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test, including: Lamb waves are excited on the surface of the thin plate under test, and time-domain vibration signals of the Lamb waves are received at multiple equally spaced detection points. A two-dimensional Fourier transform is performed on the received time-domain vibration signal to generate the phase velocity dispersion curve of the Lamb wave propagation in the thin plate under test. Based on the phase velocity dispersion curve, the phase velocity limit values of the low-order mode and the high-order mode are identified when the frequency-thickness product tends to infinity. The phase velocity limit value of the low-order mode is taken as the surface wave velocity, and the phase velocity limit value of the high-order mode is taken as the transverse wave velocity. Based on the phase velocity dispersion curve, the curvature change point of the S1 mode is identified, and the phase velocity value corresponding to the curvature change point is taken as the phase velocity of the S1 mode at the zero group velocity point.
4. The method according to claim 1, characterized in that, Based on the surface wave velocity and the transverse wave velocity, a first scanning speed is determined, and based on the phase velocity corresponding to the S1 mode at the zero group velocity point, a second scanning speed is determined, including: Based on the surface wave velocity and the transverse wave velocity, a velocity range is determined, and a target velocity within the velocity range is determined as the first scanning velocity. The phase velocity corresponding to the zero group velocity point of the S1 mode is taken as the second scan velocity.
5. The method according to claim 1, characterized in that, Based on the first scanning speed and the second scanning speed, determine the first control parameters and the second control parameters of the rotating mirror, including: Based on the first scanning speed, the first rotation speed and the first distance of the rotating mirror are determined, and the first rotation speed and the first distance are used as the first control parameters of the rotating mirror; Based on the first distance and the second scanning speed, a second rotation speed is determined, and the second rotation speed and the first distance are used as the second control parameters of the rotating mirror.
6. The method according to claim 5, characterized in that, During the laser emission onto the surface of the thin plate under test, the rotating mirror is adjusted according to the first control parameter and the second control parameter respectively to obtain a single S0 mode Lamb wave and a higher-order mode mixed Lamb wave, including: When a laser is emitted onto the surface of the thin plate under test, the rotating mirror is adjusted according to the first control parameter so that the moving speed of the laser source on the surface of the thin plate under test reaches the first scanning speed, and the received time domain signal is subjected to Fourier transform to obtain a single S0 mode Lamb wave. A laser is continuously emitted onto the surface of the thin plate under test. The rotating mirror is fixed at the first distance, and the rotation speed of the rotating mirror is increased from the first rotation speed to the second rotation speed so that the moving speed of the laser source on the surface of the thin plate under test reaches the second scanning speed. The received time-domain signal is then subjected to Fourier transform to obtain a higher-order mode mixed Lamb wave.
7. The method according to claim 1, characterized in that, After obtaining the single S0 mode Lamb wave and the higher-order mode mixed Lamb wave, the following is also included: In the higher-order mode mixed Lamb wave, the S1 mode zero group velocity Lamb wave is extracted, and the thickness of the thin plate to be measured is determined based on the S1 mode zero group velocity Lamb wave.
8. A selective excitation device for Lamb waves, characterized in that, include: The reference velocity acquisition module is used to acquire the surface wave velocity, transverse wave velocity, and phase velocity of the S1 mode at the zero group velocity point of the thin plate under test. The scanning speed determination module is used to determine a first scanning speed based on the surface wave velocity and the transverse wave velocity, and to determine a second scanning speed based on the phase velocity corresponding to the S1 mode at the zero group velocity point. The control parameter determination module is used to determine the first control parameter and the second control parameter of the rotating mirror based on the first scanning speed and the second scanning speed. The Lamb wave acquisition module is used to adjust the rotating mirror according to the first control parameter and the second control parameter respectively during the process of emitting laser to the surface of the thin plate under test, so as to obtain a single S0 mode Lamb wave and a higher-order mode mixed Lamb wave; wherein, the higher-order mode mixed Lamb wave includes an S1 mode zero group velocity Lamb wave.
9. An electronic device, characterized in that, The electronic device includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program that can be executed by the at least one processor to enable the at least one processor to perform the selective excitation method of the Lamb wave according to any one of claims 1-7.
10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that cause a processor to execute the selective excitation method of the Lamb wave according to any one of claims 1-7.