Nonlinear surface acoustic wave modeling method for characterizing mechanical properties of material surface

Abstract

The invention discloses a nonlinear surface acoustic wave modeling method for characterizing mechanical properties of a material surface. The nonlinear surface acoustic wave modeling method comprises the following steps: S1, selecting a potential function to calculate an effective elastic constant of a material; s2, calculating a theoretical wave equation of the surface acoustic wave; s3, establishing a molecular dynamics model of the anisotropic material, extracting atomic position information, and distributing displacement and speed for atoms according to a theoretical wave equation to obtain an initial surface acoustic wave sinusoidal waveform; s4, performing numerical integration on the Newton motion equation based on a speed-Verlet algorithm to update the position and speed of atoms, and realizing dynamic propagation of the surface acoustic wave on the surface of the model; s5, extracting waveform information of the surface acoustic wave in each period, drawing a # imgabs0 # curve by adopting a fast Fourier transform method, and calculating a second-order nonlinear coefficient F (1 / 2); and S6, waveform sharpening caused by the up-conversion behavior of the surface acoustic wave is analyzed, the critical stress of a cuspidal point in the waveform of the surface acoustic wave is calculated, and the plastic yield strength of the surface of the anisotropic material is deduced.

Description

Technical Field

[0001] The invention belongs to the technical field of material characterization, and in particular relates to a nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of a material surface. Background Art

[0002] Surface acoustic waves use the free surface as a waveguide, so their energy is mainly concentrated within a wavelength range below the surface. However, due to the elastic nonlinearity of the material, high-amplitude surface acoustic waves will undergo nonlinear sharpening during propagation, resulting in microcracks or plastic deformation on the surface of anisotropic materials, which provides new possibilities for the study of surface properties.

[0003] Due to the limitations of current theoretical models at the continuum level, molecular dynamics methods are used to study the propagation characteristics of nonlinear surface acoustic waves. Molecular dynamics methods play an important role in materials science research because of their ability to track changes in material microstructure, accurate performance prediction, flexible adjustment of simulation conditions, and high efficiency and economy. Unlike continuum-level methods, molecular dynamics methods only require a suitable interatomic potential function to define all mechanical, thermodynamic and other properties of the material, which provides new opportunities for studying the nonlinear propagation of surface acoustic waves.

[0004] Therefore, it is hoped to develop a molecular dynamics modeling method that can be used to simulate the propagation of surface acoustic waves on the surface of materials. This method can be used to study the nonlinear evolution process of surface acoustic waves and at the same time characterize the mechanical properties of the material surface. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of material surfaces, which can perform computational analysis on some nonlinear characteristics of surface acoustic waves that are difficult to study theoretically.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of material surfaces is implemented in the LAMMPS computing system and includes the following steps:

[0008] S1. Use potential function to calculate the effective elastic constants of anisotropic materials;

[0009] S2. Calculate the theoretical wave equation of surface acoustic waves based on the continuum theory and effective elastic constants;

[0010] S3, establishing a molecular dynamics model of anisotropic materials and extracting atomic position information in the molecular dynamics model, and assigning displacement and velocity to atoms according to the theoretical wave equation, and finally obtaining an initial surface acoustic wave sinusoidal waveform;

[0011] S4, based on the velocity-Verlet algorithm, numerically integrate the Newtonian equations of motion to update the positions and velocities of atoms, thereby realizing the dynamic propagation of surface acoustic waves on the surface of the molecular dynamics model;

[0012] S5. Extract the waveform information of the surface acoustic wave propagating over time in each period and draw it using the fast Fourier transform method Curve, calculate the second-order nonlinear coefficient F(1 / 2) used to characterize the elastic mechanical properties of anisotropic materials;

[0013] S6. Analyze the waveform sharpening caused by the upconversion behavior of the surface acoustic wave, calculate the critical stress of the sharp point in the waveform of the surface acoustic wave, and derive the plastic yield strength of the surface of the anisotropic material.

[0014] Furthermore, in step S1, a potential function is selected and LAMMPS software is used to apply known strains in different directions to the simulation box, and C is obtained through the following stress-strain relationship: αβμv :

[0015] σ αβ =C αβμv ε μν (1)

[0016] In the formula, σ αβ is the stress tensor, ∈ μν is the strain tensor, C αβμv It refers to a 6×6 matrix consisting of 21 independent elastic constants, where α, β, μ, and v represent Cartesian coordinates;

[0017] Among them, σ αβ The Virial stress tensor is expressed in molecular dynamics and is calculated as follows:

[0018]

[0019] Where N is the total number of atoms in the LAMMPS calculation system, V is the volume of the simulation box, u(r) is the potential energy term, i and j are atoms, and m is i 、r i 、v i denote the mass, position and velocity of atom i, respectively, v α，i 、v β，i Respectively represent the speed of atom i along the α and β directions, and the vector r ij Defined as r i -r j , r α，ij 、r β，ij represent r along the α and β directions respectively ij vector.

[0020] Furthermore, in step S2, the calculation formula of the theoretical wave equation is:

[0021]

[0022] In the formula, u m represents the displacement component, m=1,3, p is the density of the anisotropic material,

[0023] Among them, the elastic constant C 11 , C 13 , C 33 , C 55 The following inequality is satisfied:

[0024] C>0,C 11 C 33 -C 13 2 >O (4)

[0025] Among them, the boundary condition of zero traction is satisfied on the surface of anisotropic material, that is:

[0026] σ 13 =σ 33 =0 (5)

[0027] In addition, the wave velocity of the surface acoustic wave propagating in an orthotropic material can be obtained from the following formula:

[0028]

[0029] Furthermore, the velocity-Verlet algorithm calculation formula for numerically integrating Newton's motion equations in step S4 is:

[0030]

[0031] in,

[0032]

[0033] In this formula, x m 、v m 、a m They represent displacement, velocity, and acceleration respectively, t represents time, and Δt represents time increment.

[0034] Furthermore, in step S5 The trajectory equation of the curve is:

[0035]

[0036] In the formula, A nrepresents the displacement amplitude of the surface acoustic wave, q0 is the fundamental frequency wave number, and n represents the harmonic order; among them, F(1 / 2) depends on the ratio of the second-order and third-order elastic constants of the anisotropic material, reflecting the elastic mechanical properties of the anisotropic material.

[0037] Furthermore, the calculation formula for the critical stress at the cusp point in the waveform of the surface acoustic wave in step S6 is:

[0038]

[0039] Where θ represents the inclination angle of the slip plane, σ max That is, the yield strength of anisotropic materials; the emergence of the cusp is due to the nonlinear evolution of the surface acoustic wave during propagation, which produces the second harmonic and causes the waveform to sharpen, and finally forms a shock wave front with a cusp.

[0040] The present invention also provides a nonlinear surface acoustic wave modeling device for characterizing the mechanical properties of a material surface, comprising:

[0041] The effective elastic constant unit is used to calculate the effective elastic constants of anisotropic materials using potential functions;

[0042] Theoretical wave equation unit, used to calculate the theoretical wave equation of surface acoustic waves based on continuum theory and calculated effective elastic constants;

[0043] The surface acoustic wave sinusoidal waveform unit is used to establish a molecular dynamics model of anisotropic materials and extract atomic position information in the molecular dynamics model, and assign displacement and velocity to atoms according to the theoretical wave equation, and finally obtain the initial surface acoustic wave sinusoidal waveform;

[0044] The position and velocity update unit is used to numerically integrate Newton's equations of motion based on the velocity-Verlet algorithm to update the positions and velocities of atoms, thereby realizing the dynamic propagation of surface acoustic waves on the surface of the molecular dynamics model;

[0045] Fourier transform unit is used to extract the waveform information of the surface acoustic wave propagating over time in each period, and draw it using the fast Fourier transform method Curve, calculate the second-order nonlinear coefficient F(1 / 2) used to characterize the elastic mechanical properties of anisotropic materials;

[0046] The critical stress calculation unit is used to analyze the waveform sharpening caused by the up-conversion behavior of the surface acoustic wave, calculate the critical stress of the cusp in the waveform of the surface acoustic wave, and derive the plastic yield strength of the surface of the anisotropic material.

[0047] The present invention also provides an electronic device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of a material surface are implemented.

[0048] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of a material surface.

[0049] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0050] 1. Accurately establish the sinusoidal waveform of surface acoustic waves: By assigning displacement and velocity to surface atoms, a molecular dynamics model of surface acoustic waves propagating on the surface of materials was successfully established, achieving accurate characterization of the mechanical properties of the material surface.

[0051] 2. Simplified definition of mechanical properties: This method only requires a suitable interatomic potential function to define all mechanical, thermodynamic and other properties of the material, which greatly simplifies the definition process of mechanical properties and improves modeling efficiency.

[0052] 3. In-depth study of nonlinear characteristics: Computational analysis of the nonlinear characteristics of surface acoustic waves at the atomic scale, especially those characteristics that are difficult to study theoretically, such as nonlinear sharpening and waveform sharpening caused by frequency conversion behavior, provides a more detailed and precise research method.

[0053] 4. Dynamic propagation process simulation: The velocity-Verlet algorithm is used to numerically integrate Newton's motion equations, dynamically update the position and velocity of atoms, and realize the dynamic propagation simulation of surface acoustic waves, which can more realistically reflect the propagation characteristics of surface acoustic waves.

[0054] 5. Fast Fourier transform analysis: The waveform information of the surface acoustic wave in each period is extracted through fast Fourier transform, and the second-order nonlinear coefficient F(1 / 2) is calculated to reflect the surface elastic mechanical properties of the material (second-order and third-order elastic constants), thereby more accurately characterizing the mechanical properties of the material.

[0055] 6. Analysis of surface plastic mechanical properties: By analyzing the waveform sharpening caused by the frequency conversion behavior of the surface acoustic wave, calculating the critical stress of the cusp, and deriving the plastic mechanical properties (yield strength) of the material surface, it provides an important reference for the application and development of the material.

[0056] 7. Wide applicability: Molecular dynamics methods have wide applicability and important roles in materials science research because of their ability to track changes in material microstructure, accurately predict performance, flexibly adjust simulation conditions, and be highly efficient and economical.

[0057] In summary, the present invention provides an efficient and accurate nonlinear surface acoustic wave modeling method, which can comprehensively characterize the surface mechanical properties of materials and has significant scientific research and engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a flow chart in an embodiment of the present invention;

[0059] Figure 2 is an initial molecular dynamics model diagram in an embodiment of the present invention;

[0060] Figure 3 A molecular dynamics model of surface acoustic waves propagating on a material surface in an embodiment of the present invention;

[0061] Figure 4 A velocity / energy diagram of a surface acoustic wave during propagation in an embodiment of the present invention;

[0062] Figure 5 It is a schematic diagram of the speed-Verlet algorithm integration principle in an embodiment of the present invention;

[0063] Figure 6 is the nonlinear coefficient F(1 / 2) calculated in the embodiment of the present invention. curve;

[0064] Figure 7 The figure is a diagram showing the process of waveform sharpening and second harmonic appearance during the propagation of surface acoustic waves in an embodiment of the present invention;

[0065] Figure 8 Schematic diagram of a critical state for calculating stress in an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0067] The present invention will be further described in detail below in conjunction with the accompanying drawings, but this is not intended to limit the present invention.

[0068] like Figure 1 As shown in FIG. 1 , a nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of a material surface is implemented in the LAMMPS computing system and specifically includes the following steps:

[0069] S1. Select appropriate potential functions to calculate the effective elastic constants of anisotropic materials. First, select appropriate potential functions according to the properties of anisotropic materials, and apply known strains in different directions of the simulation box through LAMMPS software to obtain the following stress-strain relationship:

[0070] σ αβ =C αβμν ∈ μν (1)

[0071] In the formula, σ αβ is the stress tensor, ∈ μν is the strain tensor, C αβμv It refers to a 6×6 matrix consisting of 21 independent elastic constants, where α, β, μ, and v represent Cartesian coordinates;

[0072] Among them, σ αβ The Virial stress tensor is expressed in molecular dynamics and is calculated as follows:

[0073]

[0074] Where N is the total number of atoms in the LAMMPS calculation system, V is the volume of the simulation box, u(r) is the potential energy term, i and j are atoms, and m is i 、r i 、v i denote the mass, position and velocity of atom i, respectively, v α，i 、v β，i Respectively represent the speed of atom i along the α and β directions, and the vector r ij Defined as r i -r j , r α,ij 、r β，ij represent r along the α and β directions respectively ij vector.

[0075] S2. The theoretical wave equation of surface acoustic waves is calculated based on the continuum theory and the effective elastic constant. The calculation formula of the theoretical wave equation is:

[0076]

[0077] In the formula, u m represents the displacement component, m=1,3, ρ is the density of the anisotropic material, Among them, the elastic constant C 11 , C 13 , C 33 , C 55 The following inequality is satisfied:

[0078] C>0,C 11 C 33 -C 13 2 >0 (4)

[0079] Among them, the boundary condition of zero traction is satisfied on the surface of anisotropic material, that is:

[0080] σ 13 =σ 33 =0 (5)

[0081] In addition, the velocity c of the surface acoustic wave propagating in an orthotropic material can be obtained from the following formula:

[0082]

[0083] S3, establish a molecular dynamics model of anisotropic materials and extract atomic position information in the molecular dynamics model, such as Figure 2 As shown, the displacement and velocity of the surface atoms are assigned according to the theoretical equation, and finally the initial surface acoustic wave sinusoidal waveform is obtained, as shown in Figure 3 As shown, the velocity / energy diagram during surface wave propagation can be further obtained, such as Figure 4 As shown. The details that need to be paid attention to during the modeling process are as follows: In order to achieve continuous propagation of surface acoustic waves, periodic boundary conditions are applied along the x and g directions, where the x direction is the propagation direction of the wave. In addition, there are certain requirements for the size of the molecular dynamics model, where the size L in the x direction is x is the wavelength of the surface wave, and the dimension L in the y direction y The cutoff distance r of the interatomic interaction potential should be greater than twice c , the dimension L in z direction z >3L x .

[0084] S4, based on the velocity-Verlet algorithm, the Newtonian equations of motion are numerically integrated to update the positions and velocities of atoms, thereby realizing the dynamic propagation of surface acoustic waves on the surface of the molecular dynamics model; Figure 5 As shown; the velocity-Verlet algorithm calculation formula for numerical integration of Newton's equations of motion is:

[0085]

[0086] in,

[0087]

[0088] In this formula, x m 、v m 、a m They represent displacement, velocity, and acceleration respectively, t represents time, and Δt represents time increment.

[0089] S5. Extract the waveform information of the surface acoustic wave propagating over time in each period, and use the fast Fourier transform method to draw the Curve, calculate the second-order nonlinear coefficient F(1 / 2) used to characterize the elastic mechanical properties of anisotropic materials, such as Figure 6 As shown; The trajectory equation of the curve is:

[0090]

[0091] In the formula, A n represents the displacement amplitude of the surface acoustic wave, q0 is the fundamental frequency wave number, and n represents the harmonic order; among them, F(1 / 2) depends on the ratio of the second-order and third-order elastic constants of the anisotropic material, reflecting the elastic mechanical properties of the anisotropic material.

[0092] S6. Analyze the waveform sharpening caused by the up-conversion behavior of surface acoustic waves, such as Figure 7 As shown, the critical stress of the cusp in the waveform of the surface acoustic wave is calculated, as Figure 8 As shown, the plastic yield strength of the anisotropic material surface is derived. The calculation formula for the critical stress at the cusp of the surface acoustic wave waveform is:

[0093]

[0094] Where θ represents the inclination angle of the slip plane, σ max That is, the yield strength of anisotropic materials; the emergence of the cusp is due to the nonlinear evolution of the surface acoustic wave during propagation, which produces the second harmonic and causes the waveform to sharpen, and finally forms a shock wave front with a cusp.

[0095] Preferably, an embodiment of the present application further provides a nonlinear surface acoustic wave modeling device for characterizing the mechanical properties of a material surface, comprising:

[0096] The effective elastic constant unit is used to calculate the effective elastic constants of anisotropic materials using potential functions;

[0097] Theoretical wave equation unit, used to calculate the theoretical wave equation of surface acoustic waves based on continuum theory and calculated effective elastic constants;

[0098] The surface acoustic wave sinusoidal waveform unit is used to establish a molecular dynamics model of anisotropic materials and extract atomic position information in the molecular dynamics model, and assign displacement and velocity to atoms according to the theoretical wave equation, and finally obtain the initial surface acoustic wave sinusoidal waveform;

[0099] The position and velocity update unit is used to numerically integrate Newton's equations of motion based on the velocity-Verlet algorithm to update the positions and velocities of atoms, thereby realizing the dynamic propagation of surface acoustic waves on the surface of the molecular dynamics model;

[0100] Fourier transform unit is used to extract the waveform information of the surface acoustic wave propagating over time in each period, and draw it using the fast Fourier transform method Curve, calculate the second-order nonlinear coefficient F(1 / 2) used to characterize the elastic mechanical properties of anisotropic materials;

[0101] The critical stress calculation unit is used to analyze the waveform sharpening caused by the up-conversion behavior of the surface acoustic wave, calculate the critical stress of the cusp in the waveform of the surface acoustic wave, and derive the plastic yield strength of the surface of the anisotropic material.

[0102] Preferably, the embodiments of the present application also provide a specific implementation of an electronic device capable of implementing all steps in the nonlinear surface acoustic wave modeling method for characterizing the surface mechanical properties of materials in the above embodiments, and the electronic device specifically includes the following contents:

[0103] Processor, memory, communications interface and bus;

[0104] Among them, the processor, memory, and communication interface communicate with each other through the bus; the communication interface is used to realize information transmission between related devices such as server-side devices, metering devices, and user-side devices.

[0105] The processor is used to call the computer program in the memory, and when the processor executes the computer program, all the steps in the nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of the material surface in the above embodiment are implemented.

[0106] An embodiment of the present application also provides a computer-readable storage medium capable of implementing all steps of the nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of the material surface in the above-mentioned embodiment. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements all steps of the nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of the material surface in the above-mentioned embodiment.

[0107] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the hardware + program embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0108] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0109] Although the present application provides method operation steps such as embodiments or flow charts, more or fewer operation steps may be included based on conventional or non-creative labor. The order of steps listed in the embodiments is only one way of executing the order of many steps and does not represent the only execution order. When the actual device or client product is executed, it can be executed in the order of the method shown in the embodiments or the drawings or in parallel (for example, in a parallel processor or multi-threaded processing environment).

[0110] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0111] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0112] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0113] The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. Changes and variations made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of material surfaces, implemented in a LAMMPS computing system, characterized in that: The steps include: S1. Use potential function to calculate the effective elastic constants of anisotropic materials; S2. Calculate the theoretical wave equation of surface acoustic waves based on the continuum theory and effective elastic constants; S3, establishing a molecular dynamics model of anisotropic materials and extracting atomic position information in the model, and assigning displacement and velocity to atoms according to the theoretical wave equation, and finally obtaining an initial surface acoustic wave sinusoidal waveform; S4, based on the velocity-Verlet algorithm, numerically integrate the Newtonian equations of motion to update the positions and velocities of atoms, thereby realizing the dynamic propagation of surface acoustic waves on the surface of the molecular dynamics model; S5. Extract the waveform information of the surface acoustic wave propagating over time in each period and draw it using the fast Fourier transform method Curve, calculate the second-order nonlinear coefficient F(1 / 2) used to characterize the elastic mechanical properties of anisotropic materials; S6. Analyze the waveform sharpening caused by the upconversion behavior of the surface acoustic wave, calculate the critical stress of the sharp point in the waveform of the surface acoustic wave, and derive the plastic yield strength of the surface of the anisotropic material.

2. A nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of a material surface according to claim 1, characterized in that: In step S1, a potential function is selected and LAMMPS software is used to apply known strains in different directions to the simulation box, and C is obtained through the following stress-strain relationship: αβμv : s αβ =C αβμv ∈ μv (1) In the formula, σ αβ is the stress tensor, ∈ μv is the strain tensor, C αβμv It refers to a 6 × 6 matrix consisting of 21 independent elastic constants, where α, β, μ, and v represent Cartesian coordinates; Among them, σ αβ The Virial stress tensor is expressed in molecular dynamics and is calculated as follows: Where N is the total number of atoms in the LAMMPS calculation system, V is the volume of the simulation box, u(r) is the potential energy term, i and j are atoms, and m is i 、r i ,υ i denote the mass, position and velocity of atom i, respectively, and υ α，i ,υ β，i Respectively represent the speed of atom i along the α and β directions, and the vector r ij Defined as r i -r j , r α，ij 、r β，ij represent r along the α and β directions respectively ij vector.

3. The nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of a material surface according to claim 1, characterized in that: In step S2, the calculation formula of the theoretical wave equation is: In the formula, u m represents the displacement component, m=1,3, ρ is the density of the anisotropic material, Among them, the elastic constant C 11 , C 13 , C 33 , C 55 The following inequality is satisfied: C>O,C 11 C 33 -C 13 2 >O (4) Among them, the boundary condition of zero traction is satisfied on the surface of anisotropic material, that is: s 13 =s 33 =0 (5) In addition, the velocity c of the surface acoustic wave propagating in an orthotropic material can be obtained from the following formula:

4. The nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of a material surface according to claim 1, characterized in that: The velocity-Verlet algorithm calculation formula for numerically integrating Newton's equations of motion in step S4 is: in, In this formula, x m ,υ m 、a m They represent displacement, velocity, and acceleration respectively, t represents time, and Δt represents time increment.

5. The nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of a material surface according to claim 1, characterized in that: In step S5 The trajectory equation of the curve is: In the formula, A n represents the displacement amplitude of the surface acoustic wave, q0 is the fundamental frequency wave number, and n represents the harmonic order; among them, F(1 / 2) depends on the ratio of the second-order and third-order elastic constants of the anisotropic material, reflecting the elastic mechanical properties of the anisotropic material.

6. The nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of a material surface according to claim 1, characterized in that: The calculation formula of the critical stress at the cusp point of the surface acoustic wave waveform in step S6 is: Where θ represents the inclination angle of the slip plane, σ max That is, the yield strength of anisotropic materials; the emergence of the cusp is due to the nonlinear evolution of the surface acoustic wave during propagation, which produces the second harmonic and causes the waveform to sharpen, and finally forms a shock wave front with a cusp.

7. A nonlinear surface acoustic wave modeling device for characterizing the mechanical properties of a material surface, characterized in that: include: The effective elastic constant unit is used to calculate the effective elastic constants of anisotropic materials using potential functions; Theoretical wave equation unit, used to calculate the theoretical wave equation of surface acoustic waves based on continuum theory and calculated effective elastic constants; The surface acoustic wave sinusoidal waveform unit is used to establish a molecular dynamics model of anisotropic materials and extract atomic position information in the molecular dynamics model, and assign displacement and velocity to atoms according to the theoretical wave equation, and finally obtain the initial surface acoustic wave sinusoidal waveform; The position and velocity update unit is used to numerically integrate Newton's equations of motion based on the velocity-Verlet algorithm to update the positions and velocities of atoms, thereby realizing the dynamic propagation of surface acoustic waves on the surface of the molecular dynamics model; Fourier transform unit is used to extract the waveform information of the surface acoustic wave propagating over time in each period, and draw it using the fast Fourier transform method Curve, calculate the second-order nonlinear coefficient F(1 / 2) used to characterize the elastic mechanical properties of anisotropic materials; The critical stress calculation unit is used to analyze the waveform sharpening caused by the up-conversion behavior of the surface acoustic wave, calculate the critical stress of the cusp in the waveform of the surface acoustic wave, and derive the plastic yield strength of the surface of the anisotropic material.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the nonlinear surface acoustic wave modeling method for characterizing the surface mechanical properties of materials as described in any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the nonlinear surface acoustic wave modeling method for characterizing the mechanical properties of the material surface as described in any one of claims 1 to 6 are implemented.

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