Lamb wave mixing excitation simulation method based on small crack positioning and related device
By constructing an excitation function and a small crack simulation mesh model, and using the Lamb wave mixing excitation method, the problem of inaccurate small crack monitoring in Lamb wave simulation was solved, and efficient monitoring of early damage to train structures was achieved.
Patent Information
- Application Number
- CN202511084340.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-04
- Publication Date
- 2025-11-18
AI Technical Summary
In existing technologies, the Lamb wave simulation method is difficult to accurately describe the morphology of micro-cracks in actual engineering, resulting in unstable crack monitoring effects and making it unsuitable for early damage monitoring of train structures.
By analyzing the material and mechanical characteristics of the target structure, an excitation function is constructed, a small crack simulation mesh structure model is established, and damage analysis is performed using Lamb wave mixing excitation to obtain the damage location.
It improves the accuracy and sensitivity of microcrack monitoring, enables rapid location of early damage, significantly improves detection efficiency and accuracy, and the simulation results are closer to the actual structure.
Smart Images
Figure CN120974734A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of train safety monitoring, in particular to a Lamb wave mixing excitation simulation method based on small crack positioning and related device. BACKGROUND
[0002] Large carrying equipment such as rail vehicles has been running in complex and harsh environment for a long time, and each structure has been subjected to high strength load, which is easy to produce crack damage and threaten the safety of the train, so the positioning, identification and monitoring of structural crack damage have become an important topic to improve the safety of the structure.
[0003] In recent years, Lamb wave has been paid more and more attention in the application of structural health monitoring. Lamb wave can detect solid structure for a long distance and shows great potential in plate structure damage monitoring. In the damage diagnosis based on Lamb wave, the difference between healthy signal and damage signal is mainly concerned, and the damage feature is extracted for comparison, so as to realize damage identification and characterization.
[0004] In actual engineering, the size of early crack damage is small, generally micro small crack, but the traditional Lamb wave simulation modeling analyzes the macro crack with thickness or defines the damage area by changing the material characteristics, which is easy to cause the difference of method simulation solution and deviate from the engineering practice. It can be seen that there is no crack simulation structure that can accurately describe the crack morphology in engineering practice, and the sensitivity of Lamb wave harmonic mixing excitation to various small cracks is not the same, which seriously affects the crack monitoring effect and stability of nonlinear Lamb wave, and cannot be really applied to simulation solution and actual reference model.
[0005] Therefore, it is urgent to develop a new method for the simulation of small cracks of Lamb wave. SUMMARY
[0006] The purpose of the present application is to provide a Lamb wave mixing excitation simulation method based on small crack positioning and related device to overcome the problems in the prior art. The present application can establish a micro small crack simulation grid structure model through the physical characteristic mechanism of crack, effectively simulate the damage condition of target structure, improve the accuracy and sensitivity of crack monitoring, further monitor and evaluate the micro small crack under early damage, and strengthen the correlation degree with the actual target structure.
[0007] To achieve the above purpose, the technical scheme adopted by the present application is as follows: In a first aspect, the present application provides a Lamb wave mixing excitation simulation method based on small crack positioning, comprising the following steps: analyze the material characteristics of the target structure, confirm the size of the target structure, select the material characteristic parameters and mechanical characteristic parameters; Two Lamb waves are selected for frequency mixing excitation, and an excitation function is constructed using the property parameters of the Lamb waves and the excitation position. A mechanical model of the target structure is established based on the selected material characteristic parameters and mechanical characteristic parameters. Then, a number of small cracks of a desired set value are generated. The small cracks are imported into the mechanical model of the target structure and then the friction properties are assigned to the small cracks to establish a target structure model with small cracks. Assign solid mechanical properties to the target structure model with small cracks, set up exciters and receivers, import the excitation function into the exciter, divide the mesh, optimize the mesh distribution at the small cracks, and establish a simulation mesh structure model of the small cracks. Based on the mixing excitation frequency of the Lamb wave, the characteristic parameters are calculated and imported into the small crack simulation mesh structure model, and the calculation method of the small crack simulation mesh structure model is set. The small crack simulation mesh structure model is solved according to the calculation method of the set small crack simulation mesh structure model. The target point response data is output and received through the receiver. The Lamb wave mixing excitation effect is analyzed, and a Lamb wave mixing excitation model based on small crack simulation is established. The damage of the target structure is simulated through the Lamb wave mixing excitation model based on small crack simulation, and the damage location is obtained. Furthermore, the selection of material characteristic parameters and mechanical characteristic parameters specifically includes: Import the material density of the target structure The first parameter of linear elastic Lame Shear modulus of linear elastic Lame Poisson's ratio Pressure wave velocity and shear wave velocity ; Among them, the first parameter of the linear elastic Lame The calculation formula is: ; Shear modulus of linear elastic Lame The calculation formula is: ； In the formula, E Young's modulus; Poisson's ratio; Furthermore, the step of selecting two Lamb waves for mixing excitation and constructing an excitation function based on the attribute parameters of the Lamb waves and the excitation position specifically includes: Two Lamb waves are selected for frequency mixing excitation, namely excitation wave a and excitation wave b. The excitation frequency of excitation wave a is selected. and the excitation frequency of excitation wave b Calculate the angular frequency of the excitation wave a. and the angular frequency of the excitation wave b Then build on the surface of the target structure xy A coordinate system is uniformly set along the edge of the target structure. n There are one excitation point, and the coordinates of the excitation point are recorded. The coordinates of the excitation point are taken as the excitation position, and then the angular frequency of the excitation wave a is determined. Angular frequency of excitation wave b Constructing the excitation function based on the excitation location F a and excitation function F b ; in, ; angular frequency and angular frequency The calculation formula is: ; ; Excitation function F a and excitation function F b The calculation formula is: ; ; In the formula, Let be the excitation coefficient of the excitation wave a; Let be the excitation coefficient of the excitation wave b; rect1(t) is the excitation function. F a The gate signal is used to control the excitation function. F a The incentive range is set with a lower limit of 0 and an upper limit of [missing information]. n a T a Size is 1, baseline is 0, where, n a The number of periods set for the excitation wave a T a Let be the time length of a single period of the excitation wave a; rect2(t) is the excitation function. F b The gate signal is used to control the excitation function. F b The incentive range is set with a lower limit of 0 and an upper limit of [missing information]. n b T b, size is 1, baseline is 0, wherein n b the number of periods set for the excitation wave b, T b the length of time for a single period of the excitation wave b; the target control time delay; t the excitation function; Further, the small crack generation area is selected, the coordinate range interval of the small crack generation area position is determined, two coordinate values are randomly generated in the coordinate range interval of the small crack generation area position, the randomly generated two coordinate values are taken as the start and end positions of the small crack respectively, and it is judged whether the small crack overlaps with the generated small crack by whether the randomly generated two coordinate values have intersection with the coordinate values of the generated small crack. If there is no overlap, the randomly generated two coordinate values are retained, and the generated small crack quantity reaches the expected setting value; If there is overlap, two coordinate values are randomly generated again in the coordinate range interval of the small crack generation area position, and the above process is performed again until the generated small crack quantity reaches the expected setting value. Further, the solid mechanics characteristics of the target structure model with small cracks are given, the exciter and the receiver are set, the excitation function is introduced into the exciter, the grid is divided, and the grid distribution at the small crack is optimized, specifically including: Selecting an elastic material, giving the region freedom, setting the initial state to zero, setting the exciter and the receiver, introducing the excitation function and the excitation function into the exciter, determining the excitation direction from the Lamb wave mode of the excitation wave a and the excitation wave b, then dividing the grid, the size of the grid is determined by the wavelength, setting the grid distribution at the small crack to ensure that the number of grid distribution on the small crack is greater than or equal to 6. Wherein, the calculation formula of the wavelength is: ; ; In the formula, l is the wavelength; is the minimum value of the period length of all waves in the target structure model with small cracks; is the maximum value of the group velocity in the excitation wave a and the excitation wave b; is the maximum value of the harmonic frequency of all waves in the target structure model with small cracks; Further, the mixed frequency excitation frequency of the Lamb wave is calculated, the characteristic parameters are calculated and introduced into the small crack simulation grid structure model, and the calculation method of the small crack simulation grid structure model is set, specifically including: According to the Lamb wave mixing excitation frequency of the excitation wave a and the excitation wave b, the characteristic parameters are calculated and introduced into the small crack simulation grid structure model, the output time step is set to , the implicit generalized alpha method and the constant Newton method are used for matrix solution, and then the Jacobian matrix is updated in each iteration; wherein, is the step coefficient; Further, the small crack simulation grid structure model is solved, the target point response data is output and received by the receiver, the Lamb wave mixing excitation effect analysis is carried out, the Lamb wave mixing excitation model based on small crack simulation is established, the damage condition of the target structure is simulated through the Lamb wave mixing excitation model based on small crack simulation, and the damage position is obtained, specifically including: Solving the small crack simulation grid structure model, obtaining the model out-of-plane displacement u , filtering u , outputting and receiving the response of the target frequency by the receiver, The wave number corresponding to the target frequency is , then the amplitude of the response is normalized and Hilbert transformed to envelope, the maximum value and the time corresponding to the maximum value are extracted, according to the response of the target frequency, the maximum value and the time corresponding to the maximum value , the Lamb wave mixing excitation model based on small crack simulation is established, the damage condition of the target structure is simulated through the Lamb wave mixing excitation model based on small crack simulation, and the damage position is obtained d ; Wherein, the calculation formula of the model out-of-plane displacement u , the response , the target frequency and the wave number is: ; ; ; ; ; In the formula, is the excitation amplitude of the excitation wave a; is the excitation amplitude of the excitation wave b; is the wave number of the excitation wave a; is the wave number of the excitation wave b; is the excitation frequency of the excitation wave a; is the excitation frequency of the excitation wave b; is the distance between any point in the target structure and the excitation position; is the time elapsed since the excitation time; damage position d The calculation formula is: ; In the formula, is the group velocity corresponding to the target frequency.
[0008] In a second aspect, the present application provides a Lamb wave mixing excitation simulation system based on small crack positioning, comprising: A material characteristic analysis module is configured to analyze the material characteristics of the target structure, confirm the size of the target structure, and select material characteristic parameters and mechanical characteristic parameters. A frequency selection module is configured to select two Lamb waves for mixing excitation, and construct an excitation function through the attribute parameters of the Lamb waves and the excitation position. A model building module is configured to establish a mechanical model of the target structure according to the selected material characteristic parameters and mechanical characteristic parameters, then generate a small number of cracks, import the small cracks into the mechanical model of the target structure, and then assign the small cracks with friction properties to establish a target structure model with small cracks. A mesh division module is configured to assign the target structure model with small cracks with solid mechanics properties, set an exciter and a receiver, import the excitation function into the exciter, divide the mesh, optimize the mesh distribution at the small cracks, and establish a small crack simulation mesh structure model. A research analysis module is configured to calculate research characteristic parameters according to the mixing excitation frequency of the Lamb waves, import the small crack simulation mesh structure model, and set the calculation method of the small crack simulation mesh structure model. A solving module is configured to solve the small crack simulation mesh structure model, output and receive target point response data through the receiver, analyze the Lamb wave mixing excitation effect, establish a Lamb wave mixing excitation model based on small crack simulation, simulate the damage of the target structure through the Lamb wave mixing excitation model based on small crack simulation, and obtain the damage position.
[0009] In a third aspect, the present application provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to realize the steps of the above method.
[0010] In a fourth aspect, the present application provides a computer readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the above method.
[0011] The above technical solution has the following advantages or beneficial effects: In a first aspect, the present application provides a Lamb wave mixing excitation simulation method based on small crack positioning, which selects material characteristic parameters and mechanical characteristic parameters, constructs an excitation function through the attribute parameters and excitation position of Lamb waves, establishes a mechanical model of a target structure, a target structure model with small cracks, a small crack simulation grid structure model, and a Lamb wave mixing excitation model based on small crack simulation, can simulate the damage condition of the target structure, and obtain the damage position; the present application can simulate micro small cracks, quickly obtain the damage condition and damage position of the target structure, improve the accuracy and sensitivity of micro crack monitoring, greatly strengthen the correlation degree with the actual target structure, also significantly improve the detection and positioning efficiency, further monitor and evaluate the micro small cracks under early damage, solve the technical problem that the traditional Lamb wave mixing excitation damage monitoring method only targets macro cracks and thick cracks or defines the damage area by changing the material characteristics, and has a low correlation degree with the actual target structure.
[0012] In a second aspect, the present application provides a Lamb wave mixing excitation simulation system based on small crack positioning, which can fully consider the material characteristics and mechanical properties of the target structure through a material characteristic analysis module and a model building module, establish a simulation model highly similar to the target structure, make the simulation result more close to the actual situation, and improve the correlation degree with the actual target structure; through an automatic simulation analysis and solving process, the damage condition and damage position of the target structure can be quickly obtained, which greatly shortens the detection cycle and improves the detection efficiency compared with the traditional method.
[0013] In a third aspect, the present application provides a computer device, which can efficiently implement the steps of the Lamb wave mixing excitation simulation method based on small crack positioning of the present application through a specific computer program executed by a processor, can accurately perform numerical calculation and logical judgment when performing data processing tasks, and avoid errors caused by human factors; at the same time, since the computer program has high stability and reliability, the accuracy and consistency of the data processing result can be ensured.
[0014] In a fourth aspect, the present application provides a computer readable storage medium, by programming the steps of the Lamb wave mixing excitation simulation method based on small crack positioning of the present application into a computer program and storing it on the computer readable storage medium, the user can easily load these programs onto any compatible computer device and execute without reprogramming or converting the code, greatly improving the convenience and flexibility of program execution. BRIEF DESCRIPTION OF DRAWINGS
[0015] Figure 1 A flowchart of the Lamb wave mixing excitation simulation method based on small crack positioning of the present application; Figure 2 A target structure simulation effect diagram of the preferred embodiment of the present application; Figure 3 A small crack simulation effect diagram of the preferred embodiment of the present application; Figure 4 A response acceptance signal time domain diagram of the preferred embodiment of the present application; Figure 5 A response acceptance signal frequency domain diagram of the preferred embodiment of the present application; Figure 6 A structure diagram of the computer device of the present application. DETAILED DESCRIPTION
[0016] The present application will be further described below in conjunction with specific embodiments, which are explanatory rather than limiting of the present application. In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application. It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. 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 including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.
[0017] Embodiments: The application is applicable to COMSOL software (COMSOL Multiphysics).
[0018] Referring to Figure 1 , the application provides a Lamb wave mixing excitation simulation method based on small crack positioning, comprising the following steps: Step one: analyzing material characteristics of a target structure, confirming the size of the target structure, and selecting material characteristic parameters and mechanical characteristic parameters; Specifically, the material characteristic parameters and the mechanical characteristic parameters are selected, and specifically include: According to the material type of the target structure, the material density of the target structure is imported , the first parameter of linear elasticity Lame , the shear modulus of linear elasticity Lame , the Poisson's ratio , the pressure wave velocity , and the shear wave velocity ; Among them, the first parameter of linear elasticity Lame The calculation formula is: ; The shear modulus of linear elasticity Lame The calculation formula is: ； In the formula, E Young's modulus; Poisson's ratio; Step two: selecting two Lamb waves for mixing excitation, constructing an excitation function through the attribute parameters and excitation positions of the Lamb waves, specifically including: Select two Lamb waves for mixing excitation, which are excitation wave a and excitation wave b, select the excitation frequency of the excitation wave a and the excitation frequency of the excitation wave b, calculate the angular frequency of the excitation wave a and the angular frequency of the excitation wave b, respectively, then establish xy a coordinate system on the surface of the target structure, uniformly set n excitation points on the edge of the target structure, record the coordinates of the excitation points , take the coordinates of the excitation points as the excitation positions, and then construct the excitation function according to the angular frequency of the excitation wave a, the angular frequency F of the excitation wave b, and the excitation position a and the excitation functionF b ; wherein the angular frequency and the angular frequency are calculated as follows: ; ; the excitation function F a and the excitation function F b are calculated as follows: ; ; wherein, is the excitation coefficient of the excitation wave a; is the excitation coefficient of the excitation wave b; rect1(t) is the gate signal of the excitation function F a , used to control the excitation interval of the excitation function F a , set as the lower limit of 0 and the upper limit of n a T a , the size is 1, and the baseline is 0, wherein, n a is the number of periods set for the excitation wave a, T a is the time length of a single period of the excitation wave a; rect2(t) is the gate signal of the excitation function F b , used to control the excitation interval of the excitation function F b , set as the lower limit of 0 and the upper limit of n b T b , the size is 1, and the baseline is 0, wherein n b is the number of periods set for the excitation wave b, T b is the time length of a single period of the excitation wave b; is the target control time delay; t is the excitation function; Step three: according to the selected material characteristic parameters and mechanical characteristic parameters, a mechanical model of the target structure is established, then a small crack of a desired set value is generated, the small crack is introduced into the mechanical model of the target structure, and the small crack is given a friction attribute, so as to establish a target structure model with a small crack; Specifically, a small crack of a desired set value is generated, which specifically includes: selecting a small crack generation area, determining a coordinate range interval of the small crack generation area position, randomly generating two coordinate values in the coordinate range interval of the small crack generation area position, taking the two randomly generated coordinate values as the starting and ending positions of the small crack respectively, and judging whether the small crack overlaps with the generated small crack through whether the two randomly generated coordinate values have intersection with other generated small crack coordinate values; If there is no overlap, the two randomly generated coordinate values are retained, and the number of generated small cracks is waited to reach the expected set value; If there is overlap, two coordinate values are randomly generated again in the coordinate range interval of the small crack generation area position, and the above process is performed again until the number of generated small cracks reaches the expected set value; Step four: giving the target structure model with small cracks solid mechanics characteristics, setting the exciter and the receiver, importing the excitation function into the exciter, dividing the grid, optimizing the grid distribution at the small crack, and establishing a small crack simulation grid structure model; Specifically, the target structure model with small cracks is given solid mechanics characteristics, the exciter and the receiver are set, the excitation function is imported into the exciter, the grid is divided, and the grid distribution at the small crack is optimized, which specifically includes: Selecting an elastic material, giving the region degrees of freedom, setting the initial state to zero, setting the exciter and the receiver, importing the excitation function and the excitation function into the exciter, determining the excitation direction from the Lamb wave mode of the excitation wave a and the excitation wave b, then dividing the grid, the size of the grid is determined by the wavelength, setting the grid distribution at the small crack, and ensuring that the number of grid distribution on the small crack is ≥6; Wherein, the calculation formula of the wavelength is: ; ; In the formula, l is the wavelength; is the minimum value of the period length of all waves in the target structure model with small cracks; is the maximum value of the group velocity in the excitation wave a and the excitation wave b; is the maximum value of the harmonic frequency of all waves in the target structure model with small cracks; Step five: according to the mixing frequency of the Lamb wave, calculate the research characteristic parameters and import them into the small crack simulation grid structure model, set the calculation method of the small crack simulation grid structure model, which specifically includes: According to the mixing frequency of the Lamb wave of the excitation wave a and the excitation wave b, calculate the research characteristic parameters and import them into the small crack simulation grid structure model, and set the output time step to , implicit generalized-alpha method and constant Newton method are used to solve the matrix, and then the Jacobian matrix is updated in each iteration; wherein, is a step length coefficient; is a step length coefficient; Solving the small crack simulation grid structure model, obtaining the model out-of-plane displacement u , filtering the response u , outputting and receiving the target frequency response , the wave number corresponding to the target frequency is , then the amplitude of the response is normalized and Hilbert transformed to envelope, extracting the maximum value and the time corresponding to the maximum value , establishing a Lamb wave mixed excitation model based on small crack simulation according to the response at the target frequency, the maximum value and the time corresponding to the maximum value , simulating the damage of the target structure through the Lamb wave mixed excitation model based on small crack simulation, and obtaining the damage location d ; wherein, the calculation formula of the model out-of-plane displacement u , the response , the target frequency and the wave number is: ; ; ; ; ; wherein, is the excitation amplitude of excitation wave a; is the excitation amplitude of excitation wave b; is the wave number of excitation wave a; is the wave number of excitation wave b; is the excitation frequency of excitation wave a; is the excitation frequency of excitation wave b; is the distance between any point in the target structure and the excitation position; is the time elapsed since the excitation time; damage position d The calculation formula is: In the formula, is the group velocity corresponding to the target frequency; The target structure simulation effect of the above embodiment is shown in Figure 2 , the crack simulation effect is shown in Figure 3 , the response acceptance signal time domain is shown in Figure 4 , and the response acceptance signal frequency domain is shown in Figure 5 .
[0019] In an embodiment of the present application, a Lamb wave mixing excitation simulation system based on small crack positioning is provided, comprising: a material characteristic analysis module for analyzing the material characteristics of the target structure, confirming the size of the target structure, and selecting material characteristic parameters and mechanical characteristic parameters; a frequency selection module for selecting two Lamb waves for mixing excitation, constructing an excitation function through the attribute parameters of the Lamb waves and the excitation position; a model building module for establishing a mechanical model of the target structure according to the selected material characteristic parameters and mechanical characteristic parameters, then generating a small number of cracks, importing the small cracks into the mechanical model of the target structure, and assigning friction properties to the small cracks to establish a target structure model with small cracks; a mesh division module for assigning solid mechanics properties to the target structure model with small cracks, setting an exciter and a receiver, importing the excitation function into the exciter, dividing the mesh, optimizing the mesh distribution at the small cracks, and establishing a small crack simulation mesh structure model; a research analysis module for calculating research characteristic parameters according to the mixing excitation frequency of the Lamb waves and importing them into the small crack simulation mesh structure model, and setting the calculation method of the small crack simulation mesh structure model; a solving module for solving the small crack simulation mesh structure model, outputting and receiving target point response data through the receiver, analyzing the Lamb wave mixing excitation effect, establishing a Lamb wave mixing excitation model based on small crack simulation, simulating the damage condition of the target structure through the Lamb wave mixing excitation model based on small crack simulation, and obtaining the damage position.
[0020] See Figure 6 In an embodiment of the present application, a computer device is provided, which comprises a processor and a memory for storing a computer program, the computer program comprising program instructions, and the processor is configured to execute the program instructions stored in the computer storage medium; the processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc., which are the computing core and control core of the terminal, and are suitable for implementing one or more instructions, and are particularly suitable for loading and executing one or more instructions in the computer storage medium to implement a corresponding method flow or a corresponding function; the processor in the embodiment of the present application can be used for the operation of the Lamb wave mixing excitation simulation method based on small crack positioning.
[0021] In an embodiment of the present application, a computer readable storage medium is provided, specifically a memory, which is a memory device in the computer device, and is used for storing programs and data. It can be understood that the computer readable storage medium herein can include the built-in storage medium in the computer device, and of course can also include the expansion storage medium supported by the computer device; the computer readable storage medium provides a storage space, which stores the operating system of the terminal; and in the storage space, one or more instructions suitable for being loaded and executed by the processor are also stored, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer readable storage medium herein can be a high-speed RAM memory, or a non-volatile memory such as at least one disk memory; one or more instructions stored in the computer readable storage medium can be loaded and executed by the processor to implement the corresponding steps of the Lamb wave mixing excitation simulation method based on small crack positioning in the embodiment.
[0022] Those skilled in the art will appreciate that embodiments of the application can be devised for a method, a system, or a computer program product, and accordingly, the present application can be embodied in a fully hardware embodiment, a fully software embodiment, or an embodiment combining software and hardware aspects all without departing the scope of the application. Furthermore, the present application can be implemented in the form of a computer program product on one or more computer available storage media (including but not limited to disk storage, CD-ROMs, optical storage media, etc.) having computer usable program code embodied therein.
[0023] The present application is described in reference to the flowchart and / or block diagrams of the method, apparatus (system) and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagrams, and a combination of flows and / or blocks in the flowchart and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, a special purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions, which are executed via the processor of the computer or other programmable data processing apparatus, generate a means for implementing the functions specified in the flowchart and / or block diagrams of the flowchart and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus for performing the functions specified in the flowchart and / or block diagrams of the flowchart and / or block diagrams.
[0024] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer readable memory produce a manufacture including an instruction apparatus, which implements the functions specified in the flowchart and / or block diagrams of the flowchart and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus for performing the functions specified in the flowchart and / or block diagrams of the flowchart and / or block diagrams.
[0025] These computer program instructions can also be loaded into a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable data processing apparatus to produce a computer implemented process, so that the instructions executed on the computer or other programmable data processing apparatus provide a means for implementing the functions specified in the flowchart and / or block diagrams of the flowchart and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus for performing the functions specified in the flowchart and / or block diagrams of the flowchart and / or block diagrams.
[0026] The present application establishes a Lamb wave mixing excitation model based on small crack simulation by crack physical characteristic mechanism, which can effectively simulate the damage of target structure, improve the accuracy and sensitivity of micro crack monitoring, and further monitor and evaluate the micro small cracks under early damage.
[0027] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A Lamb wave mixing excitation simulation method based on small crack localization, characterized in that, Includes the following steps: Analyze the material characteristics of the target structure, confirm the dimensions of the target structure, and select material characteristic parameters and mechanical characteristic parameters; Two Lamb waves are selected for frequency mixing excitation, and an excitation function is constructed using the property parameters of the Lamb waves and the excitation position. A mechanical model of the target structure is established based on the selected material characteristic parameters and mechanical characteristic parameters. Then, a number of small cracks of a desired set value are generated. The small cracks are imported into the mechanical model of the target structure and then the small cracks are given friction properties to establish a target structure model with small cracks. Assign solid mechanical properties to the target structure model with small cracks, set up exciters and receivers, import the excitation function into the exciter, divide the mesh, optimize the mesh distribution at the small cracks, and establish a simulation mesh structure model of the small cracks. Based on the mixing excitation frequency of the Lamb wave, the characteristic parameters are calculated and imported into the small crack simulation mesh structure model, and the calculation method of the small crack simulation mesh structure model is set. The small crack simulation mesh structure model is solved according to the calculation method of the set small crack simulation mesh structure model. The target point response data is output and received by the receiver. The Lamb wave mixing excitation effect is analyzed, and a Lamb wave mixing excitation model based on small crack simulation is established. The damage of the target structure is simulated by the Lamb wave mixing excitation model based on small crack simulation, and the damage location is obtained.
2. The Lamb wave mixing excitation simulation method based on small crack localization according to claim 1, characterized in that, The selection of material characteristic parameters and mechanical characteristic parameters specifically includes: Import the material density of the target structure The first parameter of linear elastic Lame Shear modulus of linear elastic Lame Poisson's ratio Pressure wave velocity and shear wave velocity ; Among them, the first parameter of the linear elastic Lame The calculation formula is: ； Shear modulus of linear elastic Lame The calculation formula is: ； In the formula, E Young's modulus; It is Poisson's ratio.
3. The Lamb wave mixing excitation simulation method based on small crack localization according to claim 1, characterized in that, The step of selecting two Lamb waves for frequency mixing excitation and constructing an excitation function based on the attribute parameters of the Lamb waves and the excitation position specifically includes: Two Lamb waves are selected for frequency mixing excitation, namely excitation wave a and excitation wave b. The excitation frequency of excitation wave a is selected. and the excitation frequency of excitation wave b Calculate the angular frequency of the excitation wave a. and the angular frequency of the excitation wave b Then build on the surface of the target structure xy A coordinate system is uniformly set along the edge of the target structure. n There are one excitation point, and the coordinates of the excitation point are recorded. The coordinates of the excitation point are taken as the excitation position, and then the angular frequency of the excitation wave a is determined. Angular frequency of excitation wave b Constructing the excitation function based on the excitation location F a and excitation function F b ; in, ; angular frequency and angular frequency The calculation formula is: ； ； Excitation function F a and excitation function F b The calculation formula is: ； ； In the formula, Let be the excitation coefficient of the excitation wave a; Let be the excitation coefficient of the excitation wave b; rect1(t) is the excitation function. F a The gate signal is used to control the excitation function. F a The incentive range is set with a lower limit of 0 and an upper limit of [missing information]. n a T a Size is 1, baseline is 0, where, n a The number of periods set for the excitation wave a T a Let be the time length of a single period of the excitation wave a; rect2(t) is the excitation function. F b The gate signal is used to control the excitation function. F b The incentive range is set with a lower limit of 0 and an upper limit of [missing information]. n b T b Size is 1, baseline is 0, where n b The number of periods set for the excitation wave b. T b The duration of a single cycle of the excitation wave b; Control the time delay for the target; t Here is the activation function.
4. The Lamb wave mixing excitation simulation method based on small crack localization according to claim 1, characterized in that, The generation of the desired number of small cracks specifically includes: Select the region where the small cracks are generated, determine the coordinate range of the region where the small cracks are generated, and randomly generate two coordinate values within the coordinate range of the region where the small cracks are generated. Use the two randomly generated coordinate values as the start and end positions of the small cracks, respectively. Determine whether the small cracks coincide with the coordinate values of other generated small cracks by whether the two randomly generated coordinate values intersect with the coordinate values of other generated small cracks. If there is no overlap, retain the two randomly generated coordinate values until the number of generated small cracks reaches the desired set value; If there is overlap, two coordinate values are randomly generated again within the coordinate range of the small crack generation area, and the above process is repeated until the number of generated small cracks reaches the desired set value.
5. The Lamb wave mixing excitation simulation method based on small crack localization according to claim 1, characterized in that, The process of imparting solid mechanical properties to the target structural model with small cracks, setting up exciters and receivers, importing the excitation function into the exciter, meshing, and optimizing the mesh distribution at the small cracks specifically includes: Choose an elastic material, assign degrees of freedom to the region, set the initial state to zero, set up an exciter and receiver, and set the excitation function. and excitation function Import the exciter, determine the excitation direction by the Lamb wave modes of excitation wave a and excitation wave b, then divide the mesh, the size of the mesh is determined by the wavelength, set the mesh distribution at the small crack, and ensure that the number of meshes on the small crack is ≥6; The formula for calculating wavelength is as follows: ； ； In the formula, l Wavelength; The minimum period length of all waves in the target structure model with small cracks; Let be the maximum group velocity in excitation wave a and excitation wave b; This represents the maximum harmonic frequency of all waves in the target structure model with small cracks.
6. The Lamb wave mixing excitation simulation method based on small crack localization according to claim 1, characterized in that, The step involves calculating the characteristic parameters based on the mixing excitation frequency of the Lamb wave and importing them into the small crack simulation mesh structure model. The calculation method for the small crack simulation mesh structure model is then set, specifically including: Based on the Lamb wave mixing excitation frequencies of excitation waves a and b, the characteristic parameters are calculated and imported into the small crack simulation mesh structure model. The output time step is set to... The implicit generalized α method and the constant Newton method are used to solve the matrix, and the Jacobian matrix is updated in each iteration; where, This is the step size coefficient.
7. The Lamb wave mixing excitation simulation method based on small crack localization according to claim 1, characterized in that, The solution of the small crack simulation mesh structure model outputs and receives target point response data through a receiver, performs Lamb wave mixing excitation effect analysis, establishes a Lamb wave mixing excitation model based on small crack simulation, simulates the damage of the target structure using the Lamb wave mixing excitation model based on small crack simulation, and obtains the damage location, specifically including: Solve the simulation mesh structure model of the small crack to obtain the out-of-plane displacement of the model. u ,right u The filter is applied, and the output is received by the receiver at the target frequency. Response at the location Target frequency The corresponding wave number is Then respond The amplitude is normalized and subjected to Hilbert transform to obtain the envelope, and the maximum value is extracted. Sum and maximum value The corresponding time Based on the response at the target frequency Maximum value Sum and maximum value The corresponding time A Lamb wave mixing excitation model based on small crack simulation was established. The damage of the target structure was simulated using this model, and the damage location was obtained. d ; Among them, the model out-of-plane displacement u ,response Target frequency and wave number The calculation formula is: ； ； ； ； ； In the formula, Let a be the excitation amplitude of the excitation wave a; Let the amplitude of the excitation wave b be the excitation value; The wave number of the excitation wave a; The wave number of the excitation wave b; Let be the excitation frequency of the excitation wave 'a'; Let b be the excitation frequency of the excitation wave; The distance between any point in the target structure and the excitation location; This refers to the time elapsed since the start of the incentive period; Damage location d The calculation formula is: ； In the formula, The group velocity corresponding to the target frequency.
8. A Lamb wave mixing excitation simulation system based on small crack localization, characterized in that, include: The material characteristic analysis module is used to analyze the material characteristics of the target structure, confirm the size of the target structure, and select material characteristic parameters and mechanical characteristic parameters. The frequency selection module is used to select two Lamb waves for frequency mixing excitation and construct the excitation function based on the attribute parameters of the Lamb waves and the excitation position. The model building module is used to build a mechanical model of the target structure based on the selected material characteristic parameters and mechanical characteristic parameters. Then, it generates a desired number of small cracks, imports the small cracks into the mechanical model of the target structure, assigns friction properties to the small cracks, and builds a target structure model with small cracks. The mesh generation module is used to assign solid mechanical properties to the target structural model with small cracks, set up exciters and receivers, import the excitation function into the exciter, generate meshes, optimize the mesh distribution at the small cracks, and establish a simulation mesh structure model of the small cracks. The research and analysis module is used to calculate the research characteristic parameters based on the mixing excitation frequency of the Lamb wave and import them into the small crack simulation mesh structure model, and to set the calculation method of the small crack simulation mesh structure model. The solver module is used to solve the small crack simulation mesh structure model, output the target point response data received by the receiver, perform Lamb wave mixing excitation effect analysis, establish a Lamb wave mixing excitation model based on small crack simulation, simulate the damage of the target structure through the Lamb wave mixing excitation model based on small crack simulation, and obtain the damage location.
9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1-7.
10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1-7.