Periodic structure stress detection method and device, and electronic device

Abstract

The application provides a stress detection method and device of a periodic structure and electronic equipment, and can be applied to the field of stress detection. The method comprises the following steps: obtaining the expression of the parameters in the coefficient form partial differential equation through the fluctuation control equation of the periodic unit and the wave vector scanning path of the irreducible Brillouin zone in the wave vector space; obtaining the position coordinates of multiple wave vectors by performing wave vector path scanning on the irreducible Brillouin zone; applying different external stress conditions to the simulation model of the periodic unit, and obtaining the dispersion curves under different external stress conditions according to the position coordinates of the multiple wave vectors by using the expression of the parameters, and obtaining a stress detection model according to the frequency interval of the stop band in the dispersion curves; and exciting the periodic structure by using a preset excitation signal, so as to process the received detection signal by using the stress detection model, and obtaining a target external stress. The method solves the stress detection problem of the periodic structure, and improves the accuracy of the stress detection of the periodic structure.

Description

Technical Field

[0001] This application relates to the field of stress detection technology, and in particular to a stress detection method, apparatus and electronic equipment for periodic structures. Background Technology

[0002] Periodic structures, due to their numerous advantages such as lightweight, high strength, high energy absorption capacity, and customizable thermal and acoustic properties, have been widely used in cutting-edge fields such as aerospace, defense, automotive, and biomedical implants. During service, these periodic structures inevitably endure complex external mechanical loads, leading to stress within their internal structures. The accumulation and distribution of this stress directly affect the load-bearing capacity, fatigue life, and overall safety of the periodic structure.

[0003] Although various stress measurement techniques exist, they all exhibit significant limitations when applied to periodic materials with complex internal structures, making accurate stress measurement difficult. Therefore, how to effectively detect stress in periodic structures is a technical problem that needs to be solved in related technologies. Summary of the Invention

[0004] In view of the above problems, this application provides a stress detection method, apparatus and electronic device for periodic structures.

[0005] According to the first aspect of this application, a stress detection method for a periodic structure is provided, comprising:

[0006] For any periodic unit in a periodic structure, the expression for the parameter in the coefficient form of the partial differential equation corresponding to the periodic unit is obtained by using the wave control equation of the periodic unit and the wave vector scanning path of the periodic unit in the irreducible Brillouin zone in the wave vector space.

[0007] Wave vector path scanning is performed on the irreducible Brillouin zone of the periodic unit to obtain the position coordinates of multiple wave vectors in the irreducible Brillouin zone;

[0008] By applying different external stress conditions to the simulation model corresponding to the periodic unit, and using the coefficient form of partial differential equations and their parameter expressions, based on the position coordinates of multiple wave vectors in the irreducible Brillouin zone, dispersion curves under different external stress conditions are obtained by combining the external stress field and the position coordinates of the wave vectors. The dispersion curves indicate how the characteristic frequency of the corresponding position of the wave vector in the irreducible Brillouin zone changes with the position coordinates of the wave vector.

[0009] Based on the frequency range of the stopband in the dispersion curves under different applied stress conditions, a stress detection model is obtained; the stress detection model is used to capture the correlation between the frequency range of the stopband and the applied stress.

[0010] A pre-set excitation signal is used to excite the periodic structure to receive a detection signal for the periodic structure, and the detection signal is processed using the stress detection model to obtain the target external stress on the periodic structure.

[0011] A second aspect of this application provides a stress detection device for a periodic structure, comprising: a first acquisition module, a wave vector path scanning module, a second acquisition module, a third acquisition module, and a processing module.

[0012] The first obtaining module is used to obtain the expression of the parameters in the coefficient form partial differential equation corresponding to any periodic unit in the periodic structure by using the wave control equation of the periodic unit and the wave vector scanning path of the periodic unit in the irreducible Brillouin zone in the wave vector space.

[0013] The wave vector path scanning module is used to perform wave vector path scanning on the irreducible Brillouin zone of the periodic cell to obtain the position coordinates of multiple wave vectors in the irreducible Brillouin zone.

[0014] The second acquisition module is used to apply different external stress conditions to the simulation model corresponding to the periodic unit, and use the coefficient form of partial differential equations and their parameter expressions to obtain the dispersion curves under different external stress conditions based on the position coordinates of multiple wave vectors in the irreducible Brillouin zone, in combination with the external stress field and the position coordinates of the wave vectors; wherein, the dispersion curves indicate the change of the characteristic frequency of the corresponding position of the wave vector in the irreducible Brillouin zone with the change of the position coordinates of the wave vector.

[0015] The third acquisition module is used to obtain a stress detection model based on the frequency range of the stopband in the dispersion curve under different applied stress conditions; wherein, the stress detection model is used to capture the correlation between the frequency range of the stopband and the applied stress.

[0016] The processing module is used to excite the periodic structure using a preset excitation signal, so as to receive the detection signal for the periodic structure, and process the detection signal using the stress detection model to obtain the target external stress on the periodic structure.

[0017] A third aspect of this application provides an electronic device comprising: one or more processors; and a memory for storing one or more computer programs, wherein the one or more processors execute the one or more computer programs to implement the steps of the method described above.

[0018] A fourth aspect of this application also provides a computer-readable storage medium having a computer program or instructions stored thereon, which, when executed by a processor, implement the steps of the above-described method.

[0019] The fifth aspect of this application also provides a computer program product, including a computer program or instructions that, when executed by a processor, implement the steps of the above-described method.

[0020] The stress detection method for periodic structures provided in this application utilizes the characteristics of centrosymmetric periodic structures and introduces the irreducible Brillouin zone of periodic elements in wave vector space. By combining the wave control equation and the wave vector scanning path of the irreducible Brillouin zone, the applied stress on a single periodic element can characterize the applied stress on the entire periodic structure. Furthermore, an applied stress field is introduced, incorporating the applied stress into the boundary conditions. This allows the dispersion curves under different applied stresses to be obtained using coefficient-form partial differential equations. Therefore, by using a stress detection model based on the frequency range of the stopband in the dispersion curves under different applied stresses, the correlation between the detection signal and the applied stress can be captured, thus enabling the determination of the target applied stress on the periodic structure. This solves the problem of stress detection for periodic structures and improves the accuracy of stress detection for periodic structures. Attached Figure Description

[0021] The above-mentioned contents, other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0022] Figure 1 The diagram illustrates an application scenario of a stress detection method for a periodic structure according to an embodiment of this application.

[0023] Figure 2 A flowchart of a stress detection method for a periodic structure according to an embodiment of this application is shown;

[0024] Figure 3 A schematic diagram of a periodic structure according to an embodiment of this application is shown;

[0025] Figure 4 A schematic diagram of a periodic unit in a periodic structure according to an embodiment of this application is shown;

[0026] Figure 5 A schematic diagram of the irreducible Brillouin zone of a periodic cell in wave vector space according to an embodiment of this application is shown;

[0027] Figure 6 A schematic diagram of the dispersion curve under no external stress according to an embodiment of this application is shown;

[0028] Figure 7 A schematic diagram of the dispersion curve under an applied stress of 100 MPa according to an embodiment of this application is shown;

[0029] Figure 8A schematic diagram of the dispersion curve under an applied stress of 200 MPa according to an embodiment of this application is shown;

[0030] Figure 9 A schematic diagram of the detection signal according to an embodiment of this application is shown;

[0031] Figure 10 A structural block diagram of a stress detection device for a periodic structure according to an embodiment of this application is shown; and

[0032] Figure 11 A block diagram of an electronic device suitable for implementing a stress detection method for a periodic structure according to an embodiment of this application is shown. Detailed Implementation

[0033] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0035] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0036] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0037] In the process of developing this application, it was discovered that with the rapid development of advanced manufacturing technologies such as additive manufacturing (3D printing), periodic structures with complex internal geometries, especially lattice materials, honeycomb sandwich structures, and composite materials with periodic reinforcements such as metal lattices, composite lattices, and acoustic / mechanical metamaterials manufactured through advanced technologies such as additive manufacturing (e.g., 3D printing), are increasingly widely used. These structures generate internal stress during service, and the accumulation and distribution of stress directly affect the structure's load-bearing capacity, fatigue life, and overall safety.

[0038] For example, stress concentration regions are potential sources of crack initiation and structural failure. Therefore, the ability to accurately and non-destructively detect and monitor the stress distribution within these structures is invaluable for structural integrity assessment, predicting remaining life, and preventing catastrophic accidents. However, periodic structures, composed of numerous repeating micro-unit cells, have extremely complex internal geometries and contain a large number of interfaces and free surfaces. This unique configuration presents significant challenges to stress detection that are not present in traditional materials science.

[0039] Currently, various stress measurement technologies exist in the engineering field, but they all exhibit significant limitations when applied to periodic materials with complex internal structures. For example, contact measurement technology, the most traditional strain measurement method, is limited by its localized measurement, invasiveness and influence, and pre-installation requirements; optical non-contact measurement technology is limited by its inability to obtain stress information inside the structure; and X-ray non-destructive testing technology is limited by the fact that the penetration depth of X-rays is usually only at the micrometer level, which limits it to surface stress measurement and cannot meet the needs of detecting stress in structures, while also requiring a specific operating environment.

[0040] Therefore, existing stress detection technologies are mainly applied and developed for conventional components with simple, continuous geometric shapes, such as plates, shells, pipes, and beams. Whether it is the contact strain gauge method or the non-contact traditional ultrasonic method (based on the acoustoelastic effect), X-ray diffraction method, or optical measurement method, their design principles and applicable scope are all centered around these homogeneous or near-homogeneous continuums.

[0041] Therefore, there is a lack of effective methods in the relevant technologies for non-invasive quantitative stress assessment of periodic structures.

[0042] Therefore, embodiments of this application provide a stress detection method for periodic structures, which achieves accurate detection of external stress on periodic structures while bypassing the invasiveness, damage, or limitations of traditional detection methods.

[0043] Figure 1An application scenario diagram of the stress detection method for a periodic structure according to an embodiment of this application is shown.

[0044] like Figure 1 As shown, the application scenario 100 according to this embodiment may include a server 101, a periodic structure 102, and a sensor 103.

[0045] Server 101 can, for any periodic unit in the periodic structure 102, obtain the expression of the parameters in the coefficient form partial differential equation corresponding to the periodic unit through the wave control equation of the periodic unit and the wave vector scanning path of the irreducible Brillouin region of the periodic unit in the wave vector space. It can also perform wave vector path scanning on the irreducible Brillouin region of the periodic unit to obtain the position coordinates of multiple wave vectors in the irreducible Brillouin region. Thus, by applying different external stress conditions to the simulation model corresponding to the periodic unit, and using the coefficient form partial differential equation and its parameter expression, based on the position coordinates of multiple wave vectors in the irreducible Brillouin region, it can obtain the dispersion curves under different external stress conditions by combining the external stress field and the position coordinates of the wave vectors.

[0046] Therefore, a stress detection model can be obtained based on the frequency range of the stopband in the dispersion curves under different applied stress conditions; the stress detection model is used to capture the correlation between the frequency range of the stopband and the applied stress.

[0047] In actual stress detection, a preset excitation signal is used to excite the periodic structure 102 so that the sensor 103 receives the detection signal for the periodic structure 102 and sends the received detection signal to the server 101.

[0048] Server 101 can also use a stress detection model to process the detection signal and obtain the target external stress on the periodic structure.

[0049] The following will be based on Figure 1 The described scene, through Figures 2-9 The stress detection method for periodic structures according to embodiments of this application will be described in detail.

[0050] Figure 2 A flowchart of a stress detection method for a periodic structure according to an embodiment of this application is shown.

[0051] like Figure 2 As shown, the stress detection method 200 for this periodic structure includes operations S210 to S250.

[0052] In operation S210, for any periodic unit in the periodic structure, the expression for the parameter in the coefficient form partial differential equation corresponding to the periodic unit is obtained by using the wave control equation of the periodic unit and the wave vector scanning path of the periodic unit in the irreducible Brillouin zone in the wave vector space.

[0053] In one embodiment, the periodic structure is a centrally symmetric structure. For example, a periodic structure can be understood as an infinite repetition of centrally symmetric planar square units, that is, a periodic unit is a centrally symmetric planar square unit in a periodic structure.

[0054] Figure 3 A schematic diagram of a periodic structure according to an embodiment of this application is shown.

[0055] like Figure 3 The diagram shows a partial schematic of a periodic structure. Periodic unit 310 is a unit in the periodic structure, and the periodic structure can be obtained by infinitely repeating the periodic unit 310.

[0056] In one embodiment, the periodic unit 310 can be based on a periodic vector. and To obtain a periodic structure. Among them, It can characterize the periodic unit according to the horizontal periodicity. Movement, that is, moving one cycle unit in the horizontal direction. A periodic unit that is adjacent in the horizontal direction can be obtained; It can characterize the periodic unit according to the longitudinal period. Movement, that is, movement within a periodic unit in the longitudinal direction. This allows us to obtain a periodic unit that is vertically adjacent.

[0057] In one embodiment, the periodic structure may be a metallic solid, and the solid phase of the periodic structure may be composed of a linearly elastic, homogeneous, dissipative, and isotropic material.

[0058] According to embodiments of this application, since the solid-phase material of the periodic structure satisfies "homogeneity and isotropy," when the periodic structure is subjected to an applied uniform stress, the applied uniform stress will form a uniform stress field inside the periodic structure, meaning that the applied stress at any point inside the periodic structure has the same effect. Furthermore, since the periodic structure is an infinite repetition of periodic units, the stress state of each periodic unit is completely consistent. Therefore, by analyzing any periodic unit in the periodic structure, the analysis of the entire periodic structure can be achieved.

[0059] Figure 4 A schematic diagram of a periodic unit in a periodic structure according to an embodiment of this application is shown.

[0060] like Figure 4 As shown, for any periodic element in a periodic structure, considering the stress on the plane, it can be obtained through two orthogonal unit vectors. - Define a two-dimensional plane containing the periodic element, which will be used for subsequent stress analysis of the periodic element based on this two-dimensional plane.

[0061] Based on this, by analyzing the propagation of waves within a periodic cell, we can obtain the wave control equation for the periodic cell, which is used to constrain the propagation of waves within the periodic cell.

[0062] In one embodiment, based on the wave control equation, the applied stress on the periodic cell affects the propagation of the wave within the periodic cell.

[0063] Due to the extremely complex internal geometry of periodic structures, existing stress detection technologies often fail. Therefore, by combining the unique wave characteristics of periodic structures, wave vector space is introduced to analyze the periodicity of the structure in wave vector space.

[0064] For centrosymmetric periodic structures, which also exhibit periodicity in wave vector space, the first Brillouin zone, defined by reciprocal lattice vectors of the periodic units in wave vector space, is the most fundamental wave vector region. Based on this, utilizing symmetry, the first Brillouin zone can be further compressed into a minimal, non-redundant region, namely the irreducible Brillouin zone. The irreducible Brillouin zone is the smallest part of the first Brillouin zone that cannot be further simplified after symmetry operations (such as rotation and mirroring).

[0065] Figure 5 A schematic diagram of the irreducible Brillouin zone of a periodic cell in wave vector space according to an embodiment of this application is shown.

[0066] like Figure 5 As shown, the area enclosed by the arrows is the irreducible Brillouin zone.

[0067] in, It can represent the horizontal axis of the irreducible Brillouin zone in wave vector space. It can represent the vertical axis of the irreducible Brillouin zone in wave vector space.

[0068] In one embodiment, such as Figure 5 The path shown, starting from the origin and following the arrow direction until returning to the origin, is the wave vector scan path of the irreducible Brillouin zone of a periodic unit in wave vector space. Specifically... Figure 5 The closed boundary of the irreducible Brillouin zone enclosed by the middle arrow.

[0069] In one embodiment, in order to address the impact of the internal geometry and complexity of the periodic structure on stress detection, an irreducible Brillouin zone is introduced. Thus, by combining the wave control equation of the periodic element and the wave vector scanning path of the irreducible Brillouin zone of the periodic element in wave vector space, the applied stress on a single periodic element can be used to characterize the applied stress on the entire periodic structure.

[0070] In one embodiment, coefficient-form partial differential equations are used to characterize the wave motion process within a periodic unit. The software for multiphysics simulation includes a solver for the coefficient-form partial differential equations corresponding to the periodic unit; the coefficient-form partial differential equations corresponding to this solver are then the coefficient-form partial differential equations corresponding to the periodic structure. This multiphysics simulation software can introduce an applied stress field into the periodic unit. Therefore, by combining the wave control equations of the periodic unit and the wave vector scanning path of the irreducible Brillouin zone of the periodic unit in wave vector space, and representing them with coefficient-form partial differential equations, the expressions for the parameters in the coefficient-form partial differential equations can be obtained.

[0071] In operation S220, wave vector path scanning is performed on the irreducible Brillouin zone of the periodic cell to obtain the position coordinates of multiple wave vectors in the irreducible Brillouin zone.

[0072] In one embodiment, the shape of the irreducible Brillouin zone of the periodic unit is determined by the structural characteristics of the periodic structure itself. Thus, the periodic unit is not limited to square units, but can also be any other geometric configuration with central symmetry.

[0073] According to an embodiment of this application, wave vector path scanning is performed on the irreducible Brillouin zone of the periodic unit, that is, scanning the closed boundary of the irreducible Brillouin zone. The position coordinates of multiple wave vectors in the irreducible Brillouin zone are the coordinates of each position on the closed boundary of the irreducible Brillouin zone in wave vector space.

[0074] In one embodiment, the position coordinates of the wave vector are determined based on the length of the periodic unit.

[0075] by Figure 5 Taking the irreducible Brillouin zone of the periodic unit shown as an example, if the length of the selected periodic structural element is L, that is, the length of the periodic unit is L, then Figure 5 The square shown has a length of 2π / L, therefore in the irreducible Brillouin zone, the wave vector can travel from the origin along the direction of the arrow ( Direction) calculated to The position, and then along Direction calculation to The position of the wave vector is determined by moving it along the closed boundary of the irreducible Brillouin zone, and then returning it to the origin. Based on this, the position coordinates of multiple wave vectors can be obtained by moving the wave vector along the closed boundary of the irreducible Brillouin zone.

[0076] In operating S230, by applying different external stress conditions to the simulation model corresponding to the periodic unit, and using the coefficient form of partial differential equations and their parameter expressions, based on the position coordinates of multiple wave vectors in the irreducible Brillouin zone, the dispersion curves under different external stress conditions are obtained by combining the external stress field and the position coordinates of the wave vectors.

[0077] The dispersion curve indicates how the characteristic frequency at the position of the wave vector in the irreducible Brillouin zone changes with the position coordinates of the wave vector.

[0078] In one embodiment, a simulation model corresponding to the periodic unit can be constructed first in the software used for multiphysics simulation.

[0079] According to the embodiments of this application, by applying different external stress conditions to the simulation model corresponding to the periodic unit, and using the coefficients to form the partial differential equation and its parameter expression, the external stress can be involved in the boundary conditions, so that the stress state of the entire periodic structure can be determined from the stress state of a single periodic unit.

[0080] Boundary conditions refer to the boundaries of periodic units, which can be determined based on the closed boundaries of irreducible Brillouin zones.

[0081] In one embodiment, the boundary conditions can be defined as "the stress on the left side of the periodic element is equal to the stress on the right side, and the stress on the upper side is equal to the stress on the lower side". Specifically, the stress magnitudes at the contact boundaries of any two adjacent periodic elements (such as the right boundary of the previous element and the left boundary of the next element, the lower boundary of the previous element and the upper boundary of the next element) are equal.

[0082] Therefore, during simulation, only different external stresses need to be applied to a single periodic element to ensure the stress continuity of the entire periodic structure after splicing, and thus the analysis results of the periodic element can be extended to the whole.

[0083] In one embodiment, the periodic structure impedes waves of a specific frequency, and the frequency range impeded by the same periodic structure shifts under different applied stresses. Therefore, by coupling the applied stress field and the wave propagation within the periodic unit, and using coefficient-form partial differential equations, dispersion curves under different applied stresses can be obtained.

[0084] By operating S240, a stress detection model is obtained based on the frequency range of the stopband in the dispersion curves under different applied stress conditions.

[0085] Among them, the stress detection model is used to capture the correlation between the frequency range of the stopband and the applied stress.

[0086] In one embodiment, the frequency range of the stopband in the dispersion curve is used to characterize the frequency range blocked by the periodic unit, that is, the wave in the frequency range cannot pass through the periodic unit.

[0087] According to an embodiment of this application, since the frequency range blocked by the periodic unit under different applied stress conditions will shift, a stress detection model can be trained based on the frequency range of the stopband in the dispersion curve under different applied stress conditions to capture the correlation between the frequency range of the stopband and the applied stress.

[0088] In operation S250, a preset excitation signal is used to excite the periodic structure to receive a detection signal for the periodic structure, and the detection signal is processed using a stress detection model to obtain the target external stress on the periodic structure.

[0089] According to an embodiment of this application, during the actual stress detection of a periodic structure, the applied stress on the periodic structure is unknown. However, through the above operations S210 to S240, a stress detection model can be obtained, and the target applied stress on the periodic structure can be obtained through the detection signal of the periodic structure.

[0090] Therefore, in the actual stress detection process, a preset excitation signal can be used to excite one side of the periodic structure, and a detection signal can be received on the other side of the periodic structure.

[0091] According to the embodiments of this application, since the stress detection model can capture the correlation between the frequency range of the stopband and the applied stress, the target applied stress on the periodic structure can be obtained by processing the detection signal through the stress detection model.

[0092] According to embodiments of this application, by utilizing the characteristics of a centrally symmetric periodic structure and introducing an irreducible Brillouin zone for the periodic unit in wave vector space, and combining the wave control equation and the wave vector scanning path of the irreducible Brillouin zone, the applied stress on a single periodic unit can characterize the applied stress on the entire periodic structure. Furthermore, an applied stress field is introduced, incorporating the applied stress into the boundary conditions. This allows the dispersion curves under different applied stresses to be obtained using coefficient-form partial differential equations. Therefore, by using a stress detection model based on the frequency range of the stopband in the dispersion curves under different applied stresses, the correlation between the detection signal and the applied stress can be captured, thereby obtaining the target applied stress on the periodic structure. This solves the problem of stress detection for periodic structures and improves the accuracy of stress detection for periodic structures.

[0093] According to an embodiment of this application, the expression for the parameter in the coefficient form partial differential equation corresponding to the periodic unit is obtained by using the wave control equation of the periodic unit and the wave vector scanning path of the irreducible Brillouin zone of the periodic unit in the wave vector space. This includes: substituting the wave vector scanning path of the irreducible Brillouin zone into the wave control equation to obtain the wave control equation in the physical space; and comparing the wave control equation in the physical space with the coefficient form partial differential equation to obtain the expression for the parameter in the coefficient form partial differential equation.

[0094] According to embodiments of this application, the state of a plane subjected to applied stress is considered. It can represent a displacement vector field, which is a position vector. The function. Among them, Indicates matrix transpose. It can represent the displacement in the first direction. It can represent the displacement in the second direction. It can represent the coordinates in the first direction. This can represent the coordinates in the second direction, where the first and second directions are perpendicular to each other. This position vector. Spanning two orthogonal unit vectors - The defined two-dimensional plane, i.e. Figure 4 The plane shown.

[0095] Based on this, the fluctuation control equation of the periodic unit can be shown in the following formula (1).

[0096] (1);

[0097] in, It can represent the density of periodic structures. and The elastic constants of a material with a periodic structure can be used to represent its elastic constants. It can represent the gradient. It can represent divergence. It can represent the displacement vector of a wave within a periodic unit. It can represent the displacement vector The second derivative, It can be represented as the Laplace operator.

[0098] In one embodiment, the applied stress on the periodic element does not affect the expression of the wave control equation, but it does affect the elastic constant in the wave control equation. That is, since the applied stress on the periodic element affects the elastic constant, the propagation of the wave within the periodic element will also be affected.

[0099] According to embodiments of this application, for wave propagation within a periodic unit, a free dynamic solution can be sought using the form of a periodic wave, the solution of which is expressed as a real-valued frequency in the time domain. The harmonic oscillations, in physical space, manifest as plane waves interacting with the real-valued wave vector. Periodic propagation within orthogonal planes. Among them, express Figure 5 The irreducible Brillouin zone shown along Directional coordinates express Figure 5 The irreducible Brillouin zone shown along Coordinates of direction.

[0100] In operation S220, the multiple wave vectors in the irreducible Brillouin zone refer to the reduced wave vectors in the wave vector space. Real-valued wave vector It refers to the wave vector in physical space.

[0101] In one embodiment, with Figure 5 Taking the irreducible Brillouin zone as an example, the wave vector scanning path of the irreducible Brillouin zone can be used in physical space. To represent. Among them, The imaginary unit, For time, real-valued frequency Let be the frequency of the reduced wave vector.

[0102] Based on this, the propagation of waves within a periodic structure can be represented by the following formula (2).

[0103] (2);

[0104] in, It can represent the displacement function of a wave in the plane of a periodic unit, that is, the displacement function of a wave within a periodic unit.

[0105] Based on the above formula (2), it is possible to realize the propagation of a wave from any periodic unit to the adjacent unit of any periodic unit.

[0106] Based on this, substituting formula (2) into formula (1) yields the wave control equation in physical space. Specifically, formula (2) is related to... Substituting the function expression into formula (1) The parameter in formula (1) is replaced by formula (2). .

[0107] According to the embodiments of this application, both the wave control equation in physical space and the partial differential equation in coefficient form are used to characterize the wave process in a periodic structure. Therefore, the wave control equation in physical space can be compared with the partial differential equation in coefficient form to obtain the expression of the parameters in the partial differential equation in coefficient form.

[0108] In one embodiment, the coefficient form partial differential equation corresponding to the periodic structure can be represented by the following formula (3).

[0109] (3);

[0110] in, It can be expressed as a quality coefficient. It can be expressed as the damping coefficient. It can be represented as a source term. It can be expressed as the diffusion coefficient. It can be expressed as the convection coefficient. It can be represented as a conserved flux source. It can represent the absorption coefficient. It can represent the convection coefficient of conserved flux.

[0111] In one embodiment, the expressions for each parameter in formula (3) can be as follows.

[0112] ;

[0113] ;

[0114] ;

[0115] ;

[0116] ;

[0117] ;

[0118] Among them, the real-valued wave vector in physical space is The value in the direction ,exist The value in the direction .

[0119] It can be seen that, based on the expressions of each parameter in the above formula (3), the determination of the specific value of each parameter is related to the position coordinates of the real wave vector and the elastic constant.

[0120] According to an embodiment of this application, the wave control equation characterizes the equation for wave propagation within a periodic cell, the wave vector scanning path characterizes the movement path of the wave vector within the irreducible Brillouin zone, the elastic constants in the wave control equation are related to the applied stress on the periodic cell, and the expression of the parameters can be used to characterize the relationship between the parameters and the position coordinates of the wave vector and the elastic constants in the irreducible Brillouin zone.

[0121] In one embodiment, the irreducible Brillouin zone of the periodic unit is scanned by wave vector through the above operation S220. The position coordinates of multiple wave vectors in the irreducible Brillouin zone are the position coordinates of the reduced wave vector in wave vector space. The position coordinates of the real-valued wave vector in physical space can be obtained based on the position coordinates of the reduced wave vector in wave vector space.

[0122] Therefore, in response to the above operation S230, when different external stresses are applied to the simulation model corresponding to the periodic element, the elastic constants of the simulation model of the periodic element will change accordingly. However, when performing external stress simulation on the periodic element, its elastic constants will automatically change under different external stresses, that is, it is not necessary to determine the specific value of the elastic constants under the applied stress.

[0123] In one embodiment, when performing stress simulation on a periodic element, the corresponding parameter values ​​can be obtained by substituting the position coordinates of the real-valued wave vector into the expression of the parameters. The characteristic frequency at the position corresponding to the wave vector can be obtained by substituting the specific parameter values ​​of each parameter into formula (3). .

[0124] According to the embodiments of this application, the expression of each parameter in the coefficient form partial differential equation is determined based on the wave control equation in physical space and the wave vector scanning path in the irreducible Brillouin zone. This is so that when performing stress simulation on the periodic unit, the stress field applied to the simulation model based on the position coordinates of the wave vector can follow the periodicity and be reflected in the entire periodic structure. Thus, the dispersion curves under different applied stresses can be obtained through the above formula (3), i.e., the coefficient form partial differential equation, and then used to obtain the stress detection model.

[0125] Based on the above, by substituting formula (2) into formula (1), we can obtain the eigenvalue problem, in which the sought eigenvalues ​​are those that span across... Figure 5 The reduced wave vector of the closed boundary of the irreducible Brillouin zone shown in the triangle frequency .

[0126] The following examples illustrate the application of no external stress, 100 MPa external stress, and 200 MPa external stress to the simulation model of the periodic element.

[0127] Figure 6A schematic diagram of the dispersion curve under no external stress according to an embodiment of this application is shown.

[0128] like Figure 6 As shown, the frequency range 610 is the stopband frequency range in the dispersion curve without external stress.

[0129] Figure 7 A schematic diagram of the dispersion curve under an applied stress of 100 MPa according to an embodiment of this application is shown.

[0130] like Figure 7 As shown, the frequency range 710 is the stopband frequency range in the dispersion curve under an applied stress of 100MPa.

[0131] Figure 8 A schematic diagram of the dispersion curve under an applied stress of 200 MPa according to an embodiment of this application is shown.

[0132] like Figure 8 As shown, the frequency range 810 is the stopband frequency range in the dispersion curve under an applied stress of 200MPa.

[0133] based on Figures 6-8 The x-axis of the dispersion curve is the reduced wave vector. The vertical axis represents the frequency f, where the frequency f is used to represent the reduced wave vector. frequency Furthermore, the same reduced wave vector The following corresponds to multiple frequencies, that is, any reduced wave vector Substituting the position coordinates of the corresponding real-valued wave vector into formula (3) will yield multiple frequencies.

[0134] And, as Figures 6-8 As shown, the widths of the frequency ranges of the stopband in the dispersion curves under different applied stresses are similar. For example, the widths of frequency ranges 610, 710, and 810 are similar, but the frequency ranges of the stopband in the dispersion curves under different applied stresses have shifted.

[0135] The following example uses a stress detection model as a function.

[0136] According to an embodiment of this application, a stress detection model is obtained based on the frequency range of the stopband in the dispersion curves under different applied stress conditions. This includes: for any applied stress among multiple applied stresses, analyzing the frequency range of the stopband under any applied stress and the frequency range of the stopband without applied stress to determine the blocking frequency offset of the simulation model under any applied stress and without applied stress; determining the stopband offset of the simulation model under any applied stress and without applied stress based on the starting frequency offset and ending frequency offset of the blocking frequency offset; and determining the parameters of the stress detection model based on the blocking frequency offset and stopband offset of each of the multiple applied stresses to obtain the stress detection model.

[0137] Among them, different external stress conditions include no external stress conditions and external stress conditions. No external stress conditions include no external stress when the external stress is 0, and external stress conditions include multiple external stresses when the external stress is not 0. The blocking frequency offset includes blocking start frequency offset, blocking center frequency offset, and blocking end frequency offset.

[0138] In one embodiment, the stress detection model can be as shown in the following formula (4).

[0139] (4);

[0140] in, For external stress, To block the start frequency offset, To block the termination frequency offset, To block the center frequency offset, This is the stopband offset. , , , , These are the weighting coefficients for the change in blocking start frequency, the change in blocking end frequency, the change in blocking center frequency, and the stopband offset, respectively, with M being the offset coefficient.

[0141] In one embodiment, the parameters of the stress detection model are... , , , And M.

[0142] In one embodiment, since the periodic structure hinders the propagation of waves of a specific frequency and the frequency range hindered by the periodic structure will shift under different applied stresses, the offset of the blocking frequency of the simulation model under any applied stress and under no applied stress can be determined by analyzing the dispersion curve of any applied stress and the dispersion curve without applied stress.

[0143] According to the embodiments of this application, by substituting the blocking frequency offset and stopband offset of each of the multiple applied stresses into the above formula (4), a set of equations for solving the parameters can be constructed, and the parameters of the above formula (4) can be obtained by solving them. , , , And M, that is, the parameters of the stress detection model are obtained by solving.

[0144] Based on this, and using the known parameters, a stress detection model can be obtained.

[0145] According to the embodiments of this application, based on the dispersion curves under different applied stress conditions, the blocking frequency offset of the simulation model under any applied stress and under no applied stress can be determined. Furthermore, based on the known function architecture (i.e., the above formula (4)), the parameters of the stress detection function can be obtained through the corresponding applied stress and blocking frequency offset, thereby obtaining the stress detection model. In the subsequent actual stress detection process, the target applied stress on the periodic structure can be obtained through the stress detection model, thus improving the stress detection efficiency.

[0146] According to embodiments of this application, by analyzing the frequency range of the stopband under any applied stress and the frequency range of the stopband without applied stress, the blocking frequency offset of the simulation model under any applied stress and without applied stress is determined, including: obtaining the blocking start frequency offset of the simulation model under any applied stress and without applied stress based on the start frequency of the frequency range of the stopband under any applied stress and without applied stress; obtaining the blocking end frequency offset of the simulation model under any applied stress and without applied stress based on the end frequency of the frequency range of the stopband under any applied stress and without applied stress; obtaining the blocking center frequency offset of the simulation model under any applied stress and without applied stress based on the center frequency of the frequency range of the stopband under any applied stress and without applied stress.

[0147] According to embodiments of this application, the starting frequency, ending frequency, and center frequency of wave blocking by the simulation model can be determined based on the frequency range of the stopband in the dispersion curve.

[0148] by Figures 6-8 For example, Figure 6 In the frequency range of 610 in the stopband of the dispersion curve without external stress, frequency B is the starting frequency and frequency D is the ending frequency. Figure 7 In the frequency range 710 of the stopband in the dispersion curve under an applied external stress of 100MPa, frequency H is the starting frequency and frequency G is the ending frequency. Figure 8In the frequency range 810 of the stopband in the dispersion curve under an applied external stress of 200MPa, frequency A is the starting frequency and frequency L is the ending frequency.

[0149] In one embodiment, based on the starting frequencies of the frequency ranges of the stopbands of any applied stress and no applied stress, the offset of the wave blocking starting frequency of the simulation model under any applied stress and under no applied stress can be obtained. For example, the offset of the wave blocking starting frequency of the simulation model under 100MPa applied stress and under no applied stress can be the difference between frequency B and frequency H.

[0150] In one embodiment, based on the termination frequency of the frequency range of the stopband for each of the applied stress and no applied stress, the offset of the wave blocking termination frequency of the simulation model under any applied stress and under no applied stress can be obtained. For example, the offset of the wave blocking termination frequency of the simulation model under 100MPa applied stress and under no applied stress can be the difference between frequency D and frequency G.

[0151] In one embodiment, the offset of the blocking center frequency of the simulation model under any applied stress versus without applied stress can be obtained based on the center frequencies of the frequency ranges of the respective stopbands of any applied stress and no applied stress. For example, the offset of the blocking center frequency of the simulation model under 100 MPa applied stress versus without applied stress can be the difference between the median values ​​of frequencies B and D and the median values ​​of frequencies G and H.

[0152] According to embodiments of this application, by using the frequency range of the stopband in the dispersion curves under different applied stresses, the offset of the blocking start frequency, the offset of the blocking end frequency, and the offset of the blocking center frequency of the simulation model under any applied stress and without applied stress can be determined. This can be used for the parameter determination process of the stress detection model, so that the obtained stress detection model can capture the correlation between applied stress and the frequency range of the stopband.

[0153] According to an embodiment of this application, a stress detection model is used to process the detection signal to obtain the target applied stress on the periodic structure, including: determining the starting frequency of signal blocking in response to the ordinate value in the detection signal starting to decrease; determining the center frequency of signal blocking in response to the ordinate value in the detection signal stopping decreasing; determining the ending frequency of signal blocking in response to the ordinate value in the detection signal stopping increasing; obtaining the frequency offset of the applied stress on the periodic structure relative to the frequency of wave blocking without applied stress based on the starting frequency, center frequency, and ending frequency of signal blocking of the detection signal, as well as the starting frequency, center frequency, and ending frequency of the frequency range of the stopband without applied stress; obtaining the frequency offset of the applied stress on the periodic structure relative to the frequency of wave blocking without applied stress based on the frequency offset of the blocking starting frequency and the frequency offset of the blocking ending frequency in the frequency offset of the detection signal; and substituting the frequency offset of the blocking frequency and the frequency of the blocking band in the detection signal into the stress detection model to obtain the target applied stress on the periodic structure.

[0154] According to embodiments of this application, during actual stress detection, the frequency range of the stopband in the dispersion curve of the detection signal and the signal without applied stress is analyzed to determine the frequency offset of wave blocking caused by applied stress and the absence of applied stress on the periodic structure. Based on the frequency offset of the blocking start frequency and the frequency offset of the blocking end frequency in the frequency offset of the detection signal, the stopband offset of the periodic structure under applied stress and the absence of applied stress is obtained. Specifically, the stopband offset is the sum of the frequency offset of the blocking start frequency and the frequency offset of the blocking end frequency.

[0155] Based on this, the blocking frequency offset and stopband offset of the detection signal can be substituted into the stress detection model (formula (4) above) to obtain the target external stress on the periodic structure.

[0156] Figure 9 A schematic diagram of the detection signal according to an embodiment of this application is shown.

[0157] In one embodiment, the periodic structure is excited to receive a time-domain signal. The time-domain signal is processed by a fast Fourier transform to obtain a frequency-domain signal. The detection signal is obtained by normalizing the logarithm of the ordinate of the frequency-domain signal.

[0158] like Figure 9 As shown, the horizontal axis of the detected signal is frequency, and the vertical axis is the normalized log (FFT, Fast Fourier Transform), which is the value of the vertical axis of the frequency domain signal after normalization.

[0159] exist Figure 9The image shows the detection signals of the periodic structure under no external stress, with an applied external stress of 100 MPa, and with an applied external stress of 200 MPa.

[0160] Therefore, the x-coordinate of point A in the detection signal under an applied external stress of 200 MPa is... Figure 8 The x-coordinate of point A;L in the frequency range 810 shown is... Figure 8 The frequency L in the frequency range 810 shown. The x-coordinate corresponding to point B in the detected signal under no external stress is... Figure 6 The frequency B in the frequency range 610 shown is shown; the x-coordinate of point D is... Figure 6 Frequency D in the frequency range 610 shown.

[0161] Based on the above, the x-axis value corresponding to the point where the y-axis value in the detected signal begins to decrease is the starting frequency at which the signal is blocked. Figure 9 Points A and B represent the points where the ordinate value of the corresponding detected signal begins to decrease. The abscissa corresponding to point A is the starting frequency at which the signal is blocked. The abscissa value corresponding to the point where the ordinate value of the detected signal stops decreasing is the center frequency at which the signal is blocked. Figure 9 Points E and F represent the points where the vertical coordinate value of the corresponding detected signal stops decreasing. The horizontal coordinate corresponding to point E is the center frequency at which the signal is blocked. The horizontal coordinate value corresponding to the point where the vertical coordinate value of the detected signal stops increasing is the termination frequency at which the signal is blocked. Figure 9 Points L and D represent the points where the vertical coordinate value of the corresponding detected signal stops rising, and the horizontal coordinate corresponding to point L is the termination frequency at which the signal is blocked.

[0162] by Figure 9 Taking the detection signal under an applied stress of 200MPa and the detection signal without applied stress as examples, the offset of the wave blocking start frequency of the periodic structure under applied stress and without applied stress is the difference between the corresponding abscissa values ​​of point A and point B. The offset of the blocking center frequency is the difference between the corresponding abscissa values ​​of point E and point F. The offset of the blocking termination frequency is the difference between the corresponding abscissa values ​​of point L and point D.

[0163] In one embodiment, for Figure 9 The detection signal shown is under no external stress, and the blocked center frequency of this detection signal is 660kHz, i.e. Figure 6 The center frequency of the stopband frequency range in the dispersion curve without external stress shown is 660kHz, which means the center of the bandgap corresponding to the detected signal is 660kHz; for Figure 9 The detection signal shown is subjected to an applied external stress of 100 MPa. The blocked center frequency of this detection signal is 655 kHz, i.e. Figure 7 The center frequency of the stopband frequency range in the dispersion curve shown under an applied stress of 100 MPa is 655 kHz; for Figure 9 The detection signal shown is subjected to an applied external stress of 200 MPa. The center frequency of this detection signal being blocked is 650 kHz, i.e. Figure 8 The center frequency of the stopband frequency range in the dispersion curve shown under an applied stress of 200 MPa is 650 kHz.

[0164] It should be noted that, Figure 9 The diagram shows the detection signal corresponding to a known applied stress. However, in the actual stress detection process, the applied stress on the periodic structure is unknown. That is, the applied stress corresponding to the detection signal is also unknown before the detection. The applied stress corresponding to the detection signal is only determined after the detection.

[0165] According to embodiments of this application, in the actual stress detection process, by analyzing the frequency range of the stopband in the dispersion curve of the periodic structure under actual applied stress and without applied stress, the frequency offset and stopband offset of the periodic structure under applied stress and without applied stress can be obtained. Based on this, since the stress detection model has been obtained through simulation, the frequency offset and stopband offset can be substituted into the stress detection model to obtain the target applied stress on the periodic structure, thus improving the stress detection efficiency.

[0166] The following example uses a stress detection model as a machine learning model.

[0167] According to an embodiment of this application, a stress detection model is obtained based on the frequency range of the stopband in the dispersion curve under different applied stress conditions, including: training an initial stress detection model based on the frequency range of the stopband under different applied stress conditions to obtain a stress detection model.

[0168] According to embodiments of this application, an initial stress detection model can be trained based on the frequency range of each stopband under different applied stress conditions, so that the trained stress detection model can directly determine the applied stress on the periodic structure based on the detection signal.

[0169] In one embodiment, the stress detection model is trained using the frequency range of the stopband in the dispersion curve, and the detection signal is obtained during the actual stress detection process. Since the corresponding stopband frequency range can also be extracted from the detection signal, for example, in... Figure 9 The frequency range between points A and L corresponds to the frequency range of the stopband in the dispersion curve. The frequency range of the stopband in the detection signal can be identified through the stress detection model, and then the applied stress on the periodic structure can be obtained.

[0170] According to an embodiment of this application, the detection signal is processed using a stress detection model to obtain the target external stress on the periodic structure, including: inputting the detection signal into the stress detection model and outputting the target external stress on the periodic structure.

[0171] In one embodiment, the detection signal can be input into a stress detection model, which can identify the frequency range of the stopband in the detection signal and output the target external stress on the periodic structure based on the correlation between the frequency range of the stopband and the applied stress.

[0172] In one embodiment, the stress detection model may be a machine learning model such as a support vector machine (SVM), decision tree, or neural network.

[0173] According to the embodiments of this application, when the stress detection model is a machine learning model, the stress detection model can be directly trained by the frequency range of the stopband in the frequency curves under different applied stress conditions. This allows the detection signal to be directly input into the stress detection model during actual stress detection to output the applied stress on the periodic structure, thus achieving rapid stress detection.

[0174] Based on the above, the stress detection model can be either a function or a machine learning model. When the stress detection model is a function, the model input consists of the blocking frequency offset and stopband offset for the detected signal; when the stress detection model is a machine learning model, the model input is the detected signal. Furthermore, environmental parameters (such as measured temperature) can also be used as one of the model's inputs to further improve the model's accuracy in complex environments.

[0175] According to an embodiment of this application, the preset excitation signal is obtained by the following operation: determining the sweep frequency range of the preset excitation signal based on the frequency range of the respective stopband under different applied stress conditions and the preset frequency offset.

[0176] According to an embodiment of this application, after the periodic structure is subjected to external stress, the periodic structure will block the passage of signals within a certain frequency range. Furthermore, this application also determines the external stress on the periodic structure by the frequency range blocked by the periodic structure. Therefore, the detection signal obtained by exciting the periodic structure with an excitation signal needs to present a complete stopband.

[0177] Therefore, it is necessary to set a corresponding sweep frequency range for the preset excitation signal to ensure that the complete stopband can be presented in the detection signal, thereby improving the accuracy of stress detection.

[0178] In one embodiment, during the simulation phase, the frequency range of the stopband in the dispersion curves under different applied stress conditions can be obtained. Based on this, the frequency range of the stopband in the dispersion curve under the maximum applied stress and the frequency range of the stopband in the dispersion curve without applied stress can be obtained. By taking the union of these two frequency ranges, a larger frequency range can be obtained. Within the frequency range represented by this union, the frequency ranges of the stopband under different applied stresses are basically all within this union.

[0179] However, in order to ensure the stability of the detection signal and avoid the presence of a stopband in the detection signal when excitation begins, a preset frequency offset is set. The minimum value in the frequency range represented by the union is shifted forward by the preset frequency offset, and the maximum value is shifted backward by the preset frequency offset, so as to obtain the frequency sweep range of the preset excitation signal.

[0180] For example, if the frequency range represented by the union is from 400kHz to 650kHz, then the range of the sweep signal is 50kHz before 400kHz and 50kHz after 650kHz, which is the sweep range from 350kHz to 700kHz.

[0181] According to embodiments of this application, a frequency sweep interval for a preset excitation signal is determined by using the frequency range of the stopband in the dispersion curve under the maximum applied stress and the frequency range of the stopband in the dispersion curve without applied stress. This ensures that a complete stopband can be presented in the detection signal, facilitating stress detection based on the frequency range of the stopband in the detection signal. Furthermore, a preset frequency offset is set to further determine the frequency sweep interval, ensuring the stability of the detection signal. Based on this, by using the determined frequency sweep interval and exciting the periodic structure with the preset excitation signal, it can be ensured that the frequency range of the stopband can be detected regardless of the shift in the frequency range of the stopband caused by the magnitude of the applied stress on the periodic structure.

[0182] Based on the above, the stress detection method for periodic structures in this application utilizes the characteristics of centrosymmetric periodic structures and employs the irreducible Brillouin zone and reduced wave vector to realize the dispersion curves of periodic structures under different applied stresses. Instead of viewing the drift of a single frequency point in the bandgap in isolation, it is considered a "dynamic range" with rich characteristic information. The frequency response of the periodic structure is obtained through ultrasonic excitation, and a feature vector composed of multiple parameters such as the bandgap's start frequency, end frequency, center frequency, and bandgap (stopband) offset is extracted from the response curve to obtain the stress detection model. Based on this, in the actual stress detection process, the applied stress on the periodic structure can be determined by processing the received detection signal through the stress detection model.

[0183] Therefore, the stress detection method for periodic structures in this application utilizes multidimensional information from the bandgap interval of the dispersion curve under different applied stresses to solve the stress detection problem of periodic structures, thereby improving the sensitivity and accuracy of stress detection.

[0184] Based on the stress detection method for periodic structures described above, this application also provides a stress detection device for periodic structures. The following will be combined with... Figure 10 The device is described in detail.

[0185] Figure 10 A structural block diagram of a stress detection device for a periodic structure according to an embodiment of this application is shown.

[0186] like Figure 10 As shown, the stress detection device 1000 for periodic structures in this embodiment includes a first acquisition module 1010, a wave vector path scanning module 1020, a second acquisition module 1030, a third acquisition module 1040, and a processing module 1050.

[0187] The first obtaining module 1010 is used to obtain, for any periodic unit in a periodic structure, the expression for the parameters in the coefficient form of the partial differential equation corresponding to the periodic unit by using the wave control equation of the periodic unit and the wave vector scanning path of the periodic unit in the irreducible Brillouin zone in wave vector space. In one embodiment, the first obtaining module 1010 can be used to perform the operation S210 described above, which will not be repeated here.

[0188] The wave vector path scanning module 1020 is used to perform wave vector path scanning on the irreducible Brillouin zone of the periodic unit to obtain the position coordinates of multiple wave vectors in the irreducible Brillouin zone. In one embodiment, the wave vector path scanning module 1020 can be used to perform the operation S220 described above, which will not be repeated here.

[0189] The second acquisition module 1030 is used to apply different external stress conditions to the simulation model corresponding to the periodic unit, and using the coefficient form of partial differential equations and their parameter expressions, based on the position coordinates of multiple wave vectors in the irreducible Brillouin zone, to obtain the dispersion curves under different external stress conditions, combining the external stress field and the position coordinates of the wave vectors; wherein, the dispersion curves indicate the change of the characteristic frequency at the corresponding position of the wave vector in the irreducible Brillouin zone with the change of the position coordinates of the wave vector. In one embodiment, the second acquisition module 1030 can be used to perform the operation S230 described above, which will not be repeated here.

[0190] The third obtaining module 1040 is used to obtain a stress detection model based on the frequency range of the stopband in the dispersion curves under different applied stress conditions; wherein, the stress detection model is used to capture the correlation between the frequency range of the stopband and the applied stress. In one embodiment, the third obtaining module 1040 can be used to perform the operation S240 described above, which will not be repeated here.

[0191] The processing module 1050 is used to excite the periodic structure using a preset excitation signal, to receive a detection signal for the periodic structure, and to process the detection signal using a stress detection model to obtain the target applied stress on the periodic structure. In one embodiment, the processing module 1050 can be used to perform the operation S250 described above, which will not be repeated here.

[0192] According to embodiments of this application, any plurality of modules among the first obtaining module 1010, wave vector path scanning module 1020, second obtaining module 1030, third obtaining module 1040, and processing module 1050 can be combined into one module, or any one of these modules can be split into multiple modules. Alternatively, at least part of the functionality of one or more of these modules can be combined with at least part of the functionality of other modules and implemented in one module. According to embodiments of this application, at least one of the first obtaining module 1010, wave vector path scanning module 1020, second obtaining module 1030, third obtaining module 1040, and processing module 1050 can be at least partially implemented as hardware circuitry, such as a field-programmable gate array (FPGA), a programmable logic array (PLA), a system-on-a-chip, a system-on-a-substrate, a system-on-package, an application-specific integrated circuit (ASIC), or implemented in hardware or firmware by any other reasonable means of integrating or packaging the circuitry, or implemented in any one of the three implementation methods of software, hardware, and firmware, or in a suitable combination of any of these. Alternatively, at least one of the first acquisition module 1010, the wave vector path scanning module 1020, the second acquisition module 1030, the third acquisition module 1040, and the processing module 1050 can be at least partially implemented as a computer program module, which can perform corresponding functions when the computer program module is run.

[0193] Figure 11 A block diagram of an electronic device suitable for implementing a stress detection method for a periodic structure according to an embodiment of this application is shown.

[0194] like Figure 11As shown, an electronic device 1100 according to an embodiment of this application includes a processor 1101, which can perform various appropriate actions and processes according to a program stored in ROM 1102 or a program loaded from storage portion 1108 into RAM 1103. The processor 1101 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 1101 may also include onboard memory for caching purposes. The processor 1101 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of this application.

[0195] RAM 1103 stores various programs and data required for the operation of electronic device 1100. Processor 1101, ROM 1102, and RAM 1103 are interconnected via bus 1104. Processor 1101 executes various operations of the method flow according to embodiments of this application by executing programs in ROM 1102 and / or RAM 1103. It should be noted that the programs may also be stored in one or more memories other than ROM 1102 and RAM 1103. Processor 1101 may also execute various operations of the method flow according to embodiments of this application by executing programs stored in said one or more memories.

[0196] According to embodiments of this application, the electronic device 1100 may further include an input / output (I / O) interface 1105, which is also connected to a bus 1104. The electronic device 1100 may also include one or more of the following components connected to the input / output (I / O) interface 1105: an input section 1106 including a keyboard, mouse, etc.; an output section 1107 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 1108 including a hard disk, etc.; and a communication section 1109 including a network interface card such as a LAN card, modem, etc. The communication section 1109 performs communication processing via a network such as the Internet. A drive 1110 is also connected to the input / output (I / O) interface 1105 as needed. A removable medium 1111, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 1110 as needed so that computer programs read from it can be installed into the storage section 1108 as needed.

[0197] This application also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into the device / apparatus / system. The computer-readable storage medium carries one or more programs, which, when executed, implement the method according to the embodiments of this application.

[0198] According to embodiments of this application, the computer-readable storage medium can be a non-volatile computer-readable storage medium, such as including but not limited to: portable computer disks, hard disks, random access memory, read-only memory, erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this application, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. For example, according to embodiments of this application, the computer-readable storage medium may include ROM 1102 and / or RAM 1103 and / or one or more memories other than ROM 1102 and RAM 1103 described above.

[0199] Embodiments of this application also include a computer program product comprising a computer program containing program code for performing the methods shown in the flowchart. When the computer program product is run on a computer system, the program code enables the computer system to implement the stress detection method for periodic structures provided in the embodiments of this application.

[0200] When the computer program is executed by the processor 1101, it performs the functions defined in the system / apparatus of this application embodiment. According to the embodiments of this application, the systems, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0201] In one embodiment, the computer program may rely on a tangible storage medium such as an optical storage device or a magnetic storage device. In another embodiment, the computer program may also be transmitted and distributed in the form of signals over a network medium, and may be downloaded and installed via the communication section 1109, and / or installed from the removable medium 1111. The program code contained in the computer program can be transmitted using any suitable network medium, including but not limited to: wireless, wired, etc., or any suitable combination thereof.

[0202] In such an embodiment, the computer program can be downloaded and installed from a network via the communication section 1109, and / or installed from the removable medium 1111. When the computer program is executed by the processor 1101, it performs the functions defined in the system of this application embodiment. According to the embodiments of this application, the systems, devices, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0203] According to embodiments of this application, program code for executing the computer programs provided in the embodiments of this application can be written in any combination of one or more programming languages. Specifically, these computational programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, languages ​​such as Java, C++, Python, "C", or similar programming languages. The program code can be executed entirely on the user's computing device, partially on the user's device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0204] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0205] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

[0206] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Without departing from the scope of this application, those skilled in the art can make various substitutions and modifications, all of which should fall within the scope of this application.

Claims

1. A stress detection method of a periodic structure, characterized by, The stress detection method comprises: For any periodic unit in the periodic structure, the expression of the parameters in the coefficient form partial differential equation corresponding to the periodic unit is obtained through the wave fluctuation control equation of the periodic unit and the wave vector scanning path of the irreducible Brillouin zone of the periodic unit in the wave vector space; The wave vector path scanning of the irreducible Brillouin zone of the periodic unit is performed to obtain the position coordinates of a plurality of wave vectors in the irreducible Brillouin zone; By applying different external stress conditions to the simulation model corresponding to the periodic unit, and using the coefficient form partial differential equation and the expression of the parameters thereof, and according to the position coordinates of the plurality of wave vectors in the irreducible Brillouin zone, the respective dispersion curves under different external stress conditions are obtained in combination with the position coordinates of the wave vectors and the external stress field; wherein the dispersion curve indicates that the characteristic frequency of the position corresponding to the wave vector in the irreducible Brillouin zone changes with the change of the position coordinates of the wave vector; According to the frequency interval of the stop band in the respective dispersion curves under different external stress conditions, a stress detection model is obtained; wherein the stress detection model is used to capture the correlation between the frequency interval of the stop band and the external stress; Using a preset excitation signal, the periodic structure is excited to receive a detection signal for the periodic structure, and the stress detection model is used to process the detection signal to obtain a target external stress received by the periodic structure.

2. The stress detection method according to claim 1, characterized by, The wave fluctuation control equation represents the equation of wave propagation in the periodic unit, the wave vector scanning path represents the movement path of the wave vector in the irreducible Brillouin zone, the elastic constant in the wave fluctuation control equation is related to the external stress received by the periodic unit, and the expression of the parameters is used to represent the correlation between the parameters and the position coordinates of the wave vector in the irreducible Brillouin zone and the elastic constant.

3. The stress detection method according to claim 1, characterized by, The different external stress conditions include a no-external stress condition and an external stress condition, the no-external stress condition includes a no-external stress with an external stress of 0, and the external stress condition includes a plurality of external stresses with an external stress not being 0; The stress detection model is obtained according to the frequency interval of the stop band in the respective dispersion curves under different external stress conditions, comprising: For any external stress in the plurality of external stresses, By analyzing the frequency interval of the stop band under the any external stress and the frequency interval of the stop band under the no-external stress, the stop band frequency offset of the simulation model under the any external stress and under the no-external stress is determined; wherein the stop band frequency offset includes a stop band start frequency offset, a stop band center frequency offset and a stop band end frequency offset; According to the start frequency offset and the end frequency offset in the stop band frequency offset, the stop band offset of the simulation model under the any external stress and under the no-external stress is determined; According to the stop band frequency offset and the stop band offset of the plurality of external stresses, the parameters of the stress detection model are determined to obtain the stress detection model.

4. The stress detection method according to claim 3, characterized by, The stop band frequency offset of the simulation model under the any external stress and under the no-external stress is determined by analyzing the frequency interval of the stop band under the any external stress and the frequency interval of the stop band under the no-external stress, comprising: According to the start frequency of the frequency interval of the respective stopband under any of the applied stress and no applied stress, a start frequency offset of the simulation model under the any of the applied stress from the stoppage of the wave under no applied stress is obtained; According to the end frequency of the frequency interval of the respective stopband under any of the applied stress and no applied stress, an end frequency offset of the simulation model under the any of the applied stress from the stoppage of the wave under no applied stress is obtained; According to the center frequency of the frequency interval of the respective stopband under any of the applied stress and no applied stress, a center frequency offset of the simulation model under the any of the applied stress from the stoppage of the wave under no applied stress is obtained.

5. The stress detection method according to claim 4, characterized by, The processing of the detection signal by the stress detection model to obtain the target applied stress on the periodic structure comprises: determining the start frequency of signal stoppage in response to the vertical coordinate value in the detection signal starting to drop; determining the center frequency of signal stoppage in response to the vertical coordinate value in the detection signal stopping dropping; determining the end frequency of signal stoppage in response to the vertical coordinate value in the detection signal stopping rising; obtaining the frequency offset of the applied stress on the periodic structure from the stoppage of the wave under no applied stress according to the start frequency, the center frequency and the end frequency of signal stoppage of the detection signal and the start frequency, the center frequency and the end frequency of the frequency interval of the stopband under no applied stress; obtaining the stopband offset of the applied stress on the periodic structure from the stopband under no applied stress according to the start frequency offset and the end frequency offset of the stoppage in the frequency offset of the detection signal; substituting the stoppage frequency offset and the stopband offset of the detection signal into the stress detection model to obtain the target applied stress on the periodic structure.

6. The stress detection method according to claim 1, characterized by, The stress detection model is obtained according to the frequency interval of the stopband in the respective frequency dispersion curve under different applied stress conditions, and the stress detection model comprises: training an initial stress detection model based on the frequency interval of the respective stopband under different applied stress conditions to obtain the stress detection model; The processing of the detection signal by the stress detection model to obtain the target applied stress on the periodic structure comprises: inputting the detection signal into the stress detection model to output the target applied stress on the periodic structure.

7. The stress detection method according to claim 1, characterized by, The expression of the parameter in the coefficient form partial differential equation corresponding to the periodic unit is obtained through the wave motion control equation of the periodic unit and the wave vector scanning path of the irreducible Brillouin zone of the periodic unit in the wave vector space, and the expression of the parameter in the coefficient form partial differential equation corresponding to the periodic unit comprises: substituting the wave vector scanning path of the irreducible Brillouin zone into the wave motion control equation to obtain the wave motion control equation in the physical space; comparing the wave motion control equation in the physical space with the coefficient form partial differential equation to obtain the expression of the parameter in the coefficient form partial differential equation.

8. The stress detection method of claim 1, wherein, The preset excitation signal is obtained by the following operation: determining the sweep frequency interval of the preset excitation signal according to the frequency interval of the respective stopband under different applied stress conditions and a preset frequency offset.

9. A stress detection apparatus of a periodic structure, characterized by comprising: The stress detection device comprises: The first obtaining module is configured to obtain an expression of a parameter in a coefficient form partial differential equation corresponding to a periodic unit, by a wave fluctuation control equation of the periodic unit and a wave vector scanning path of an irreducible Brillouin zone of the periodic unit in a wave vector space, for any periodic unit in the periodic structure. The wave vector path scanning module is configured to perform wave vector path scanning on the irreducible Brillouin zone of the periodic unit to obtain position coordinates of a plurality of wave vectors in the irreducible Brillouin zone. The second obtaining module is configured to obtain respective dispersion curves under different applied stress conditions by applying different applied stress conditions to the simulation model corresponding to the periodic unit, and using the coefficient form partial differential equation and the expression of the parameter thereof, according to the position coordinates of the plurality of wave vectors in the irreducible Brillouin zone, in combination with the position coordinates of the wave vectors and the applied stress field; wherein the dispersion curve indicates that a characteristic frequency of a corresponding position of the wave vector in the irreducible Brillouin zone changes with the position coordinates of the wave vector. The third obtaining module is configured to obtain a stress detection model according to a frequency interval of a stop band in the respective dispersion curves under the different applied stress conditions; wherein the stress detection model is used to capture a correlation between the frequency interval of the stop band and the applied stress. The processing module is configured to excite the periodic structure by using a preset excitation signal, to receive a detection signal for the periodic structure, and to process the detection signal by using the stress detection model to obtain a target applied stress received by the periodic structure.

10. An electronic device comprising: one or more processors; a memory for storing one or more computer programs, characterized in that the one or more processors execute the one or more computer programs to implement the steps of the stress detection method according to any one of claims 1-8.

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