Single-mode Lamb wave excitation method, device, equipment and medium

Abstract

The invention discloses a single-mode Lamb wave excitation method, device, equipment and medium, an optical transducer is adopted to excite a single-mode Lamb wave, and the method comprises the following steps: determining the material type of a plate-shaped material; determining a corresponding Lamb wave phase velocity frequency dispersion curve according to the material category; according to the Lamb wave phase velocity frequency dispersion curve, determining the value range of the phase velocity when only single-mode Lamb waves exist; controlling a laser to output scanning laser; the rotating mirror is controlled to rotate at a preset rotating speed, so that the scanning laser moves at a corresponding scanning speed, the surface, close to one side of the optical transducer, of the plate-shaped material is scanned, and single-mode Lamb waves are excited; the preset rotating speed enables the phase velocity of the Lamb wave excited by the scanning laser to be within the value range of the phase velocity when only the single-mode Lamb wave exists. According to the invention, the rotating mirror is controlled to rotate at the preset rotating speed, so that the scanning laser moves at the corresponding scanning speed, and excitation of single-frequency narrow-band and single-mode lamb waves in a real sense can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of excitation of single-mode Lamb waves, and particularly to a method, device, equipment and medium for exciting single-mode Lamb waves. Background Art

[0002] According to the different displacement forms of Lamb waves propagating in a thin plate in the plate, Lamb waves are divided into symmetric modes and anti-symmetric modes. Typically, there are the lowest-order symmetric S0 mode and the lowest-order anti-symmetric A0 mode. During the excitation process of Lamb waves in a thin plate, multiple modes of Lamb waves will be excited simultaneously under the same frequency-thickness product. There are not only low-order A0 and S0 modes, but often higher-order modes will also be generated, which brings inconvenience to subsequent signal processing and damage discrimination and reduces the detection sensitivity. In order to reduce the number of modes, the frequency-thickness product used during detection is usually less than the cut-off frequency-thickness products of S1 and A1 modes. In this way, theoretically, only two modes of A0 and S0 exist simultaneously.

[0003] In order to further obtain single-mode Lamb waves, a relatively pure A0 or S0 mode is obtained by designing transducers with special structures, adopting symmetric or anti-symmetric excitation methods, and symmetrically exciting the side surface with a pulsed laser. However, these methods cannot completely excite a pure A0 or S0 mode. At the same time, piezoelectric transducers and electromagnetic ultrasonic transducers are respectively restricted by the influence of coupling agents and material conductivity, restricting their development prospects.

[0004] How to overcome the many difficulties in transducer excitation and achieve the excitation of truly single-frequency narrow-band and single-mode Lamb waves is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] The present invention provides a method, device, equipment and medium for exciting single-mode Lamb waves. By controlling the rotating mirror to rotate at a preset speed, the scanning laser can move at a corresponding scanning speed, and the excitation of truly single-frequency narrow-band and single-mode Lamb waves can be achieved.

[0006] In a first aspect, an embodiment of the present invention provides a method for exciting single-mode Lamb waves, which uses an optical transducer to excite the single-mode Lamb waves, and the optical transducer is arranged on one side of a plate-shaped material;

[0007] The optical transducer includes: a laser, a rotating mirror and a controller;

[0008] The laser is used to output a scanning laser, and the scanning laser irradiates on the rotating mirror; the rotating mirror rotates under the control of the controller, and the rotating mirror reflects the scanning laser to the surface of the plate-shaped material close to the side of the optical transducer;

[0009] The excitation method of the single-mode Lamb wave includes:

[0010] Determine the material category of the plate-shaped material;

[0011] According to the material category, determine the corresponding Lamb wave phase velocity dispersion curve;

[0012] According to the Lamb wave phase velocity dispersion curve, determine the value range of the phase velocity when only the single-mode Lamb wave exists;

[0013] Control the laser to output scanning laser;

[0014] Control the rotating mirror to rotate at a preset speed, so that the scanning laser moves at a corresponding scanning speed, scan the surface of the plate-shaped material on the side close to the optical transducer, and excite the single-mode Lamb wave;

[0015] Wherein, the preset speed makes the phase velocity of the Lamb wave excited by the scanning laser within the value range of the phase velocity when only the single-mode Lamb wave exists.

[0016] Optionally, the material category includes aluminum or steel or glass or polystyrene.

[0017] Optionally, the material category is aluminum.

[0018] Optionally, determining the value range of the phase velocity when only the single-mode Lamb wave exists according to the Lamb wave phase velocity dispersion curve includes:

[0019] According to the Lamb wave phase velocity dispersion curve, the value range of the phase velocity when only the single-mode Lamb wave exists is 0 - 3 km / s.

[0020] Optionally, determining the corresponding Lamb wave phase velocity dispersion curve according to the material category includes:

[0021] Determine the corresponding Lamb wave phase velocity dispersion curve according to the mechanical properties corresponding to the material category, and the mechanical properties include material density, Poisson's ratio, and the body wave propagation wave velocity in the plate-shaped material.

[0022] Optionally, determining the corresponding Lamb wave phase velocity dispersion curve according to the material category includes:

[0023] Measure the time-domain waveform of the Lamb wave propagating in the plate-shaped material, perform two-dimensional Fourier transform on the time-domain waveform, and determine the corresponding Lamb wave phase velocity dispersion curve.

[0024] Optionally, the scanning laser is a continuous laser.

[0025] In a second aspect, an embodiment of the present invention further provides an excitation device for single-mode Lamb waves, the device comprising:

[0026] A material category determination module for determining the material category of the plate-shaped material;

[0027] A phase velocity dispersion curve determination module for determining the corresponding Lamb wave phase velocity dispersion curve according to the material category;

[0028] A phase velocity range determination module for determining the value range of the phase velocity when only the single-mode Lamb wave exists according to the Lamb wave phase velocity dispersion curve;

[0029] A laser control module for controlling the laser to output scanning laser;

[0030] A rotating mirror control module for controlling the rotating mirror to rotate at a preset speed, so that the scanning laser moves at a corresponding scanning speed to scan the surface of the plate-shaped material on the side close to the optical transducer, and excite the single-mode Lamb wave;

[0031] Wherein, the preset speed enables the phase velocity of the Lamb wave excited by the scanning laser to be within the value range of the phase velocity when only the single-mode Lamb wave exists.

[0032] In a third aspect, an embodiment of the present invention further provides an excitation device for single-mode Lamb waves, the excitation device for single-mode Lamb waves comprising:

[0033] At least one processor; and

[0034] A memory communicatively connected to the at least one processor; wherein,

[0035] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the method for exciting single-mode Lamb waves as described in the first aspect.

[0036] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, the computer-readable storage medium stores computer instructions, and the computer instructions are used to cause a processor to execute the method for exciting single-mode Lamb waves as described in the first aspect when executed.

[0037] An embodiment of the present invention provides a method, device, equipment and medium for exciting a single-mode Lamb wave. An optical transducer is used to excite the single-mode Lamb wave, and the optical transducer is arranged on one side of a plate-shaped material. The optical transducer includes: a laser, a rotating mirror and a controller. The laser is used to output scanning laser, and the scanning laser irradiates on the rotating mirror. The rotating mirror rotates under the control of the controller, and the rotating mirror reflects the scanning laser to the surface of the plate-shaped material close to the optical transducer. The method for exciting a single-mode Lamb wave includes: determining the material category of the plate-shaped material; determining the corresponding Lamb wave phase velocity dispersion curve according to the material category; determining the value range of the phase velocity when only a single-mode Lamb wave exists according to the Lamb wave phase velocity dispersion curve; controlling the laser to output scanning laser; controlling the rotating mirror to rotate at a preset speed, so that the scanning laser moves at a corresponding scanning speed and scans the surface of the plate-shaped material close to the optical transducer to excite a single-mode Lamb wave; wherein, the preset speed enables the phase velocity of the Lamb wave excited by the scanning laser to be within the value range of the phase velocity when only a single-mode Lamb wave exists. By controlling the rotating mirror to rotate at a preset speed, the embodiment of the present invention can make the phase velocity of the Lamb wave excited by the scanning laser be within the value range of the phase velocity when only a single-mode Lamb wave exists, so as to excite a single-mode Lamb wave. The embodiment of the present invention adopts a full-optical excitation method, which has the advantages of non-contact and no need for a coupling agent, successfully realizes the excitation of a single A0 mode, and realizes the excitation of a single-mode Lamb wave with adjustable frequency. It can not only selectively excite a single-mode Lamb wave, but also match the phase velocity values corresponding to different single-mode Lamb waves according to the moving speed of the scanning laser, so as to realize the excitation of single-mode Lamb waves with different frequencies.

[0038] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0040] Figure 1 It is a schematic structural diagram of an optical transducer provided by an embodiment of the present invention;

[0041] Figure 2 It is a flowchart of a method for exciting a single-mode Lamb wave provided by an embodiment of the present invention;

[0042] Figure 3A Lamb wave phase velocity dispersion curve diagram provided by an embodiment of the present invention;

[0043] Figure 4 A schematic structural diagram of an excitation device for a single-mode Lamb wave provided by an embodiment of the present invention;

[0044] Figure 5 A schematic structural diagram of an excitation device for a single-mode Lamb wave provided by an embodiment of the present invention. Detailed implementation manners

[0045] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0046] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0047] Figure 1 A schematic structural diagram of an optical transducer provided by an embodiment of the present invention. In the embodiment of the present invention, an optical transducer is used to excite a single-mode Lamb wave. Refer to Figure 1 , the optical transducer 100 is disposed on one side of the plate-like material 200. The optical transducer 100 includes: a laser 110, a rotating mirror 120, and a controller 130.

[0048] The laser 110 is used to output a scanning laser 1, and the scanning laser 1 irradiates on the rotating mirror 120. The rotating mirror 120 rotates under the control of the controller 130, and the rotating mirror 120 reflects the scanning laser 1 to the surface of the plate-like material 200 on the side close to the optical transducer 100.

[0049] It should be noted that Figure 1 both the laser 110 and the rotating mirror 120 in are wired or wirelessly connected to the controller 130 (not shown inFigure 1 as shown.

[0050] Figure 2 A flowchart of a method for exciting a single-mode Lamb wave provided for an embodiment of the invention. This embodiment is applicable to the case of exciting a single-mode Lamb wave. This method can be executed by an excitation device for a single-mode Lamb wave, and the excitation device for a single-mode Lamb wave can be implemented in the form of hardware and / or software. Refer to Figure 2 The method for exciting a single-mode Lamb wave according to the embodiment of the invention includes the following steps:

[0051] S310. Determine the material category of the plate-like material.

[0052] Among them, the material category of the plate-like material includes metal and non-metal. Metals can be materials such as aluminum and steel, and non-metals can be materials such as glass and polystyrene.

[0053] S320. Determine the corresponding Lamb wave phase velocity dispersion curve according to the material category.

[0054] Optionally, based on the above embodiment, step S320 includes:

[0055] Determine the corresponding Lamb wave phase velocity dispersion curve according to the mechanical properties corresponding to the material category. The mechanical properties include material density, Poisson's ratio, and the body wave propagation wave velocity in the plate-like material.

[0056] Optionally, based on the above embodiment, step S320 includes:

[0057] Measure the time-domain waveform of the Lamb wave propagating in the plate-like material, perform two-dimensional Fourier transform on the time-domain waveform, and determine the corresponding Lamb wave phase velocity dispersion curve.

[0058] It can be understood that there are usually two methods for drawing the Lamb wave phase velocity dispersion curve in a plate-like material. One is to determine the corresponding Lamb wave phase velocity dispersion curve according to the mechanical properties corresponding to the material category, and the other is to measure the time-domain waveform of the Lamb wave propagating in the plate-like material, perform two-dimensional Fourier transform on the time-domain waveform, and determine the corresponding Lamb wave phase velocity dispersion curve. In the embodiment of the invention, either method can be used to draw the Lamb wave phase velocity dispersion curve, and no limitation is made here.

[0059] S330. Determine the value range of the phase velocity when only a single-mode Lamb wave exists according to the Lamb wave phase velocity dispersion curve.

[0060] It should be noted that when the phase velocity value is relatively low, theoretically there is only a single mode in the plate-like material. Based on this idea, determine the value range of the phase velocity when only a single-mode Lamb wave exists according to the Lamb wave phase velocity dispersion curve, so as to effectively excite the single-mode Lamb wave.

[0061] S340. Control the laser to output scanning laser light.

[0062] S350. Control the rotating mirror to rotate at a preset rotational speed, so that the scanning laser light moves at a corresponding scanning speed, scanning the surface of the plate-like material on the side close to the optical transducer to excite single-mode Lamb waves.

[0063] Wherein, the preset rotational speed makes the phase velocity of the Lamb waves excited by the scanning laser light within the value range of the phase velocity when only single-mode Lamb waves exist.

[0064] Continue to refer to Figure 1 , it can be known from the Figure 1 geometric relationship in that the moving speed v of the scanning laser light 1 on the surface of the plate-like material 200 on the side close to the optical transducer 100 is related to the rotational speed n of the rotating mirror and the normal distance d from the rotating mirror 120 to the surface of the plate-like material 200 on the side close to the optical transducer 100. Therefore, by controlling the rotating mirror 120 to rotate at a preset rotational speed, the scanning laser light 1 can be made to move at a corresponding scanning speed.

[0065] In the embodiment of the present invention, by controlling the rotating mirror to rotate at a preset rotational speed, the phase velocity of the Lamb waves excited by the scanning laser light can be within the value range of the phase velocity when only single-mode Lamb waves exist, so that single-mode Lamb waves can be excited. The embodiment of the present invention adopts an all-optical excitation method, which has the advantages of non-contact and no need for a coupling agent, etc., successfully realizes the excitation of a single A0 mode, realizes the excitation of single-mode Lamb waves with adjustable frequency, can not only selectively excite single-mode Lamb waves, but also match the phase velocity values corresponding to different single-mode Lamb waves according to the moving speed of the scanning laser light, and can realize the excitation of single-mode Lamb waves with different frequencies.

[0066] Optionally, on the basis of the above embodiment, the material category includes aluminum or steel or glass or polystyrene.

[0067] Optionally, on the basis of the above embodiment, the material category is aluminum.

[0068] Optionally, on the basis of the above embodiment, step S330 includes:

[0069] Determine that the value range of the phase velocity when only single-mode Lamb waves exist is 0 - 3 km / s according to the Lamb wave phase velocity dispersion curve.

[0070] Figure 3 This is a Lamb wave phase velocity dispersion curve diagram provided by the embodiment of the present invention, specifically the Lamb wave phase velocity dispersion curve of a metal aluminum plate, refer to Figure 3, in the A0 modal dispersion curve (the bottom curved line in the figure), when observed from the vertical coordinate direction, in the range of 0 - 3 km / s, there is a corresponding single A0 mode, and different phase velocity values correspond to different frequency values. Therefore, by setting a reasonable rotation speed n of the rotating mirror and the normal distance d from the rotating mirror to the surface of the plate-like material on the side close to the optical transducer, such that the scanning speed of the scanning laser is within the range of 0 - 3 km / s, the effective excitation of a single A0 mode can be achieved, and at different scanning speeds of the scanning laser, pure A0 modes with different frequencies can be excited.

[0071] It should be noted that for different materials, the Lamb wave phase velocity dispersion curves are slightly different, mainly manifested in the magnitude of the phase velocity values. Therefore, only by referring to the Lamb wave phase velocity dispersion curve of the specific material and changing the rotation speed n of the rotating mirror and the normal distance d from the mirror surface to the thin plate surface, the magnitude of the laser source moving speed V value can be determined to achieve the excitation of a single A0 mode.

[0072] Optionally, based on the above embodiments, the scanning laser is a continuous laser.

[0073] Figure 4 is a schematic structural diagram of an excitation device for a single-mode Lamb wave provided by an embodiment of the invention. Refer to Figure 4 , the device includes: a material category determination module 410, a phase velocity dispersion curve determination module 420, a phase velocity range determination module 430, a laser control module 440, and a rotating mirror control module 450.

[0074] In an embodiment of the present invention, the material category determination module 410 is used to determine the material category of the plate-like material. The phase velocity dispersion curve determination module 420 is used to determine the corresponding Lamb wave phase velocity dispersion curve according to the material category. The phase velocity range determination module 430 is used to determine the value range of the phase velocity when there is only a single-mode Lamb wave according to the Lamb wave phase velocity dispersion curve. The laser control module 440 is used to control the laser to output a scanning laser. The rotating mirror control module 450 is used to control the rotating mirror to rotate at a preset speed, such that the scanning laser moves at a corresponding scanning speed to scan the surface of the plate-like material on the side close to the optical transducer to excite a single-mode Lamb wave. Among them, the preset speed enables the phase velocity of the Lamb wave excited by the scanning laser to be within the value range of the phase velocity when there is only a single-mode Lamb wave.

[0075] The excitation device for a single-mode Lamb wave provided by an embodiment of the present invention can execute the excitation method for a single-mode Lamb wave provided by any embodiment of the present invention, and has the corresponding functional modules and beneficial effects for executing the method. For the content not described in detail in this embodiment, reference can be made to the excitation method for a single-mode Lamb wave provided by any embodiment of the present invention.

[0076] Figure 5A schematic structural diagram of an excitation device for a single-mode Lamb wave provided by an embodiment of the present invention is referred to Figure 5 , the excitation device for a single-mode Lamb wave 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 excitation device for a single-mode Lamb wave can also represent various forms of mobile devices, such as, personal digital processors, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described herein and / or claimed.

[0077] As Figure 5 shown, the excitation device 10 for a single-mode Lamb wave includes at least one processor 11, and a memory communicatively connected to the at least one processor 11, such as read-only memory (ROM) 12, random access memory (RAM) 13, etc. Among them, the memory stores a computer program executable by the at least one processor. The processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 into the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the excitation device 10 for a single-mode Lamb wave can also be stored. The processor 11, ROM 12, and RAM 13 are connected to each other through a bus 14. The input / output (I / O) interface 15 is also connected to the bus 14.

[0078] Multiple components in the excitation device 10 for a single-mode Lamb wave are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disc, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the excitation device 10 for a single-mode Lamb wave to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0079] The processor 11 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the processor 11 include but are not limited to a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the excitation method for a single-mode Lamb wave.

[0080] In some embodiments, the method for exciting a single-mode Lamb wave can be implemented as a computer program tangibly embodied 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 installed onto the single-mode Lamb wave excitation device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by the processor 11, one or more steps of the single-mode Lamb wave excitation method described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to perform the single-mode Lamb wave excitation method by any other suitable means (e.g., by means of firmware).

[0081] The various embodiments of the systems and techniques described above in this document can be implemented in digital electronic circuitry, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-chip (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a dedicated or general-purpose programmable processor that receives data and instructions from a storage system, at least one input device, and at least one output device, and transmits the data and instructions to the storage system, the at least one input device, and the at least one output device.

[0082] The computer programs for implementing the methods of the present invention can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general-purpose computer, a dedicated computer, or other programmable data processing device, such that when the computer programs are executed by the processor, the functions / operations specified in the flowchart and / or block diagram are implemented. The computer programs can be executed entirely on the machine, partially on the machine, as a stand-alone software package partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0083] In the context of the present invention, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. The computer-readable storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, the computer-readable storage medium can be a machine-readable signal medium. More specific examples of the machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0084] To provide for interaction with a user, the systems and techniques described herein can be implemented on a single-mode Lamb wave excitation 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 a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the single-mode Lamb wave excitation device. Other kinds of devices can also be used to provide for interaction with the user; for example, the 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 acoustic input, speech input, or tactile input).

[0085] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer having a graphical user interface or a web browser through which the user can interact with an implementation of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: local area network (LAN), wide area network (WAN), blockchain network, and the Internet.

[0086] A computing system may include a client and a server. The client and the server are generally far from each other and usually interact via a communication network. The client-server relationship is created by computer programs running on respective computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or a cloud host, which is a host product in the cloud computing service system, solving the defects of difficult management and weak business scalability existing in traditional physical hosts and VPS services.

[0087] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added, or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is made herein.

[0088] The above specific embodiments do not constitute a limitation on the protection scope of the present 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 principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for exciting a single-mode Lamb wave, characterized in that, An optical transducer is used to excite the single-mode Lamb wave, and the optical transducer is arranged on one side of the plate-shaped material; The optical transducer includes: a laser, a rotating mirror, and a controller; The laser is used to output scanning laser, and the scanning laser irradiates on the rotating mirror; the rotating mirror rotates under the control of the controller, and the rotating mirror reflects the scanning laser to the surface of the plate-shaped material on the side close to the optical transducer; The method for exciting the single-mode Lamb wave includes: Determine the material category of the plate-shaped material; Determine the corresponding Lamb wave phase velocity dispersion curve according to the material category; Determine the value range of the phase velocity when only the single-mode Lamb wave exists according to the Lamb wave phase velocity dispersion curve; Control the laser to output scanning laser; Control the rotating mirror to rotate at a preset speed, so that the scanning laser moves at a corresponding scanning speed, scans the surface of the plate-shaped material on the side close to the optical transducer, and excites the single-mode Lamb wave; Wherein, the preset speed makes the phase velocity of the Lamb wave excited by the scanning laser within the value range of the phase velocity when only the single-mode Lamb wave exists.

2. The excitation method of a single-mode Lamb wave according to claim 1, wherein The material category includes aluminum or steel or glass or polystyrene.

3. The method for exciting a single-mode Lamb wave according to claim 2, characterized in that, The material category is aluminum.

4. The method for exciting a single-mode Lamb wave according to claim 3, characterized in that, Determining the value range of the phase velocity when only the single-mode Lamb wave exists according to the Lamb wave phase velocity dispersion curve includes: Determine that the value range of the phase velocity when only the single-mode Lamb wave exists according to the Lamb wave phase velocity dispersion curve is 0 - 3 km / s.

5. The method for exciting a single-mode Lamb wave according to claim 1, characterized in that, Determining the corresponding Lamb wave phase velocity dispersion curve according to the material category includes: Determine the corresponding Lamb wave phase velocity dispersion curve according to the mechanical properties corresponding to the material category, and the mechanical properties include material density, Poisson's ratio, and the body wave propagation wave speed in the plate-shaped material.

6. The method for exciting a single-mode Lamb wave according to claim 1, wherein Determining the corresponding Lamb wave phase velocity dispersion curve according to the material category includes: Measure the time-domain waveform of the Lamb wave propagating in the plate-shaped material, perform two-dimensional Fourier transform on the time-domain waveform, and determine the corresponding Lamb wave phase velocity dispersion curve.

7. The excitation method of a single-mode Lamb wave according to claim 1, characterized in that The scanning laser is continuous laser.

8. An excitation device for a single-mode Lamb wave, characterized in that Including: A material category determination module, used to determine the material category of the plate-shaped material; A phase velocity dispersion curve determination module, used to determine the corresponding Lamb wave phase velocity dispersion curve according to the material category; A phase velocity range determination module, used to determine the value range of the phase velocity when only the single-mode Lamb wave exists according to the Lamb wave phase velocity dispersion curve; A laser control module, used to control the laser to output scanning laser; A rotating mirror control module, used to control the rotating mirror to rotate at a preset speed, so that the scanning laser moves at a corresponding scanning speed, scans the surface of the plate-shaped material on the side close to the optical transducer, and excites the single-mode Lamb wave; Wherein, the preset speed makes the phase velocity of the Lamb wave excited by the scanning laser within the value range of the phase velocity when only the single-mode Lamb wave exists.

9. An excitation device for a single-mode Lamb wave, characterized in that, The excitation device for the single-mode Lamb wave includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and when the computer program is executed by the at least one processor, enables the at least one processor to execute the method for exciting a single-mode 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 for implementing, when executed by a processor, the method for exciting a single-mode Lamb wave according to any one of claims 1-7.

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