Metal three-dimensional stress field imaging method, device and equipment based on ultrasonic measurement

Abstract

The invention relates to the technical field of data processing, and particularly provides a metal three-dimensional stress field imaging method, device and equipment based on ultrasonic measurement, and the method comprises the steps: obtaining a simulation direction of metal three-dimensional stress through simulation; establishing a stress reconstruction coefficient matrix based on the acoustic elasticity theoretical model of the three-dimensional stress influencing the ultrasonic sound velocity; collecting wave propagation time variation when M acoustic beams transmit the metal; and performing reconstruction solution based on the stress reconstruction coefficient matrix and the wave propagation time variation to obtain a three-dimensional stress amplitude. And performing three-dimensional stress field imaging based on the simulation direction of the three-dimensional stress and the amplitude of the three-dimensional stress so as to characterize the distribution condition of the metal three-dimensional stress field.

Description

Technical Field

[0001] The present application relates to the technical field of data processing, and in particular, to a method, device, equipment and medium for imaging a metal triaxial stress field based on ultrasonic measurement. Background Art

[0002] The triaxial stress field refers to a state in which a metal material simultaneously bears stresses in three mutually perpendicular directions. The triaxial stress can be caused by external loads during manufacturing and use, or it can be an internal self-equilibrium stress state without obvious external loads. Among them, the internal self-equilibrium stress state without obvious external loads is called residual stress. When a metal part with residual stress is subjected to an external load under working conditions, the externally applied stress is superimposed on the existing internal residual stress to form an actual triaxial stress field.

[0003] Residual stress is inevitably introduced during manufacturing processes such as machining and heat treatment of metal parts. Residual stress has a great impact on the dimensional accuracy, dimensional stability and fatigue performance of metal parts, and may lead to fatigue crack propagation, part deformation or even failure of metal parts, thus affecting the service performance of parts. Therefore, how to accurately characterize the triaxial stress field of metals is a crucial topic.

[0004] Currently, the characterization methods for the stress field of metals are mainly divided into two categories: destructive characterization methods and non-destructive characterization methods. The destructive characterization methods release the local residual stress of metal parts by mechanical means, and then obtain the local stress characteristics of the acquisition points. However, this method cannot deduce the residual stress distribution at other positions of the metal parts, and at the same time, the metal parts are damaged after detection and cannot be reused. The non-destructive characterization methods do not cause damage to metal parts. Currently, the existing non-destructive methods generally start from the response of metal parts to ultrasonic excitation and use the inversion research method to evaluate the residual stress level on the surface or near the surface of metal parts, without causing damage to the parts. However, the current characterization methods for the stress of metal parts are limited to local or near the surface, and there is an urgent need to develop new non-destructive characterization methods for the triaxial stress inside the parts. Summary of the Invention

[0005] In order to solve the above technical problems, the present application provides a method, device, equipment and medium for imaging a metal triaxial stress field based on ultrasonic measurement, so as to realize the reconstruction of the triaxial stress field inside the metal.

[0006] In a first aspect, the present application provides a method for imaging a metal triaxial stress field based on ultrasonic measurement. The method includes: obtaining the simulation directions of the metal triaxial stress through simulation; establishing a stress reconstruction coefficient matrix based on the acoustoelastic theory model in which the triaxial stress affects the ultrasonic sound velocity; collecting the change amount of the wave propagation time when M acoustic beams transmit through the metal; performing reconstruction and solution based on the stress reconstruction coefficient matrix and the change amount of the wave propagation time to obtain the amplitude of the triaxial stress; and performing imaging of the triaxial stress field based on the simulation directions of the triaxial stress and the amplitude of the triaxial stress.

[0007] In a second aspect, the present application provides an apparatus for imaging a metal triaxial stress field based on ultrasonic measurement. The apparatus includes: a stress direction acquisition module for obtaining the simulation directions of the metal triaxial stress through simulation; a coefficient matrix establishment module for establishing a stress reconstruction coefficient matrix based on the acoustoelastic theory model in which the triaxial stress affects the ultrasonic sound velocity; a wave propagation time change amount acquisition module for collecting the change amount of the wave propagation time when M acoustic beams transmit through the metal; a triaxial stress amplitude calculation module for performing reconstruction and solution based on the stress reconstruction coefficient matrix and the change amount of the wave propagation time to obtain the amplitude of the triaxial stress; and a triaxial stress imaging module for performing imaging of the triaxial stress field based on the simulation directions of the triaxial stress and the amplitude of the triaxial stress.

[0008] In a third aspect, the present application provides an electronic device. The electronic device includes an apparatus for imaging a metal triaxial stress field based on ultrasonic measurement, and the apparatus includes: one or more processors; a storage device for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the method for imaging a metal triaxial stress field based on ultrasonic measurement as described in the first aspect above.

[0009] In a fourth aspect, the present application provides a storage medium, which may be a computer-readable storage medium, having a computer program stored thereon. When the program is executed by a processor, it implements the method for imaging a metal triaxial stress field based on ultrasonic measurement as described in the first aspect above.

[0010] In a fifth aspect, an embodiment of the present application provides a computer program product, which includes a computer program or instruction. When the computer program or instruction is executed by a processor, it implements the method for imaging a metal triaxial stress field based on ultrasonic measurement as described in any one of the first aspect above.

[0011] The embodiments of the present application provide a method, apparatus, device and storage medium for imaging a metal triaxial stress field based on ultrasonic measurement, mainly including: obtaining the simulation direction of the metal triaxial stress through simulation; establishing a stress reconstruction coefficient matrix based on the acoustoelastic theory model in which the triaxial stress affects the ultrasonic sound velocity; collecting the change amount of the wave propagation time when M sound beams transmit through the metal; performing reconstruction and solution based on the stress reconstruction coefficient matrix and the change amount of the wave propagation time to obtain the triaxial stress amplitude, and performing triaxial stress field imaging based on the anti-seismic direction of the triaxial stress and the triaxial stress amplitude, so as to realize the characterization of the distribution of the metal triaxial residual stress field. Description of the Drawings

[0012] The drawings here are incorporated into the specification and constitute a part of this specification, showing the embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0014] Figure 1 It is a schematic flow chart of a method for imaging a metal triaxial stress field based on ultrasonic measurement provided by an embodiment of the present application;

[0015] Figure 2 It is a schematic calculation flow chart of the stress reconstruction coefficient matrix provided by an embodiment of the present application;

[0016] Figure 3 It is a schematic diagram of three states of the acoustoelastic theory provided by an embodiment of the present application;

[0017] Figure 4 It is a schematic diagram of the coordinate system setting and direction of the triaxial stress situation provided by an embodiment of the present application;

[0018] Figure 5 It is a schematic diagram of the grid discretization of the area to be reconstructed provided by an embodiment of the present application;

[0019] Figure 6 It is a schematic flow chart of the iterative reconstruction algorithm provided by an embodiment of the present application;

[0020] Figure 7 It is a schematic diagram of the cross-sectional residual stress distribution result in the bar thermal simulation provided by an embodiment of the present application;

[0021] Figure 8 It is a schematic diagram of the ultrasonic simulation wave field in a circular cross-section provided by an embodiment of the present application;

[0022] Figure 9 Schematic diagram of the reconstruction imaging of the residual stress field of bars based on the iterative reconstruction algorithm provided by the embodiment of the present application;

[0023] Figure 10 Schematic diagram of the structure of the metal triaxial stress field imaging device based on ultrasonic measurement provided by the embodiment of the present application;

[0024] Figure 11 Schematic diagram of the structure of the electronic device provided by the embodiment of the present application. Detailed implementation manners

[0025] In order to more clearly understand the above objects, features and advantages of the present application, the solutions of the present application will be further described below. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0026] Many specific details are set forth in the following description in order to provide a thorough understanding of the present application, but the present application may be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the present application, not all embodiments.

[0027] As used herein, the term "including" and its variants are open-ended, that is, "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the following description.

[0028] It should be noted that the concepts such as "first" and "second" mentioned in the present application are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence relationship of the functions performed by these devices, modules or units.

[0029] It should be noted that the modifications of "one" and "multiple" mentioned in the present application are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly stated in the context, it should be understood as "one or more".

[0030] The method for imaging the metal triaxial stress field based on ultrasonic measurement provided by the embodiment of the present application will be described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0031] As Figure 1 shown, the method for imaging the metal triaxial stress field based on ultrasonic measurement provided by the embodiment of the present application mainly includes steps S101-S105.

[0032] S101. Obtain the simulation direction of the metal triaxial stress through simulation.

[0033] Among them, the above-mentioned metal may include superalloys, which refer to a class of metal materials that can work for a long time under high temperatures above 600 °C and certain stress conditions without significant performance degradation.

[0034] The triaxial stress of a metal refers to the stress that a metal material simultaneously bears in three mutually perpendicular directions. The triaxial stress can be caused by external loads during manufacturing and use, or it can be an internal self-equilibrium stress state without obvious external load. The triaxial stress field imaging of a metal based on ultrasonic measurement provided by the embodiments of the present application can reconstruct and image the actual triaxial stress field caused by external loads, and can also reconstruct and image the triaxial residual stress field without external load. In the embodiments of the present application, the reconstruction and imaging of the triaxial residual stress field are taken as an example for illustration.

[0035] The triaxial residual stress of a metal exists in three mutually perpendicular directions and can be formed during material manufacturing, processing, heat treatment, and service. The existence of triaxial residual stress has an important impact on the performance of metal parts. For example, it may affect the dimensional stability, fatigue life, corrosion resistance, and overall strength of metal parts. Therefore, when designing and manufacturing metal parts, various methods are used to measure and analyze the triaxial residual stress of the metal in order to take appropriate measures to reduce the adverse effects.

[0036] Among them, the simulation direction of the triaxial stress of a metal can be understood as the direction of the triaxial stress inside the metal obtained through simulation. The above-mentioned simulation methods include but are not limited to: finite element analysis, boundary element method, phase field method, etc.

[0037] In a possible implementation, obtaining the simulation direction of the triaxial stress of a metal through simulation includes: establishing a thermodynamic simulation model of the metal based on preset thermodynamic parameters, material properties, and boundary settings; and simulating the heat treatment process of the metal based on the thermodynamic simulation model of the metal to obtain the simulation direction of the triaxial stress of the metal.

[0038] Simulating the heat treatment process of the metal through the thermodynamic finite element analysis method to obtain the simulation direction of the triaxial stress of the metal. The above-mentioned thermodynamic finite element algorithm can be implemented using finite element simulation software, and the type of finite element simulation software is not limited in the embodiments of the present application.

[0039] The thermodynamic finite element analysis method is a numerical simulation technology that combines thermal analysis and mechanical analysis to solve problems involving the coupling of temperature changes and mechanical stresses. This algorithm is mainly used to predict the response of materials or structures when heated, cooled, or experiencing temperature gradients, including thermal expansion, contraction, thermal stress, thermal deformation, and possible damage or failure.

[0040] Further, based on the thermodynamic finite element numerical simulation method, the heat treatment process of the metal is simulated to obtain the simulation direction of the triaxial stress of the metal.

[0041] Further, during the simulation process, the geometric model of the metal can adopt models of any shape such as a cylinder, a cuboid, etc., which is not specifically limited in the embodiments of the present application. Determine the temperature-dependent thermodynamic parameters involved in the heat conduction analysis according to the metal material used in the experiment, such as the coefficient of thermal expansion, thermal conductivity, specific heat capacity, density, Young's modulus, hardening coefficient, yield strength, etc.

[0042] In one example, the simulation of water quenching after solution treatment of the superalloy is to take the bar out of the solution treatment furnace at T degrees Celsius and then perform water quenching. When performing the finite element simulation analysis and calculation, first perform a thermal analysis on the superalloy, and then perform a force analysis on the results of the thermal analysis. Through the above thermodynamic finite element algorithm, the simulation direction of the triaxial stress of the superalloy can be obtained.

[0043] S102. Establish a stress reconstruction coefficient matrix based on the photoelastic theory model in which triaxial stress affects the ultrasonic sound velocity.

[0044] In the related research on the detection of triaxial stress, only the case where the propagation direction of the ultrasonic wave is parallel to the stress is often considered, that is, the longitudinal ultrasonic wave or the critically refracted longitudinal wave is affected by the uniaxial stress parallel to its propagation direction, and the corresponding analytical calculation expression is given. In the embodiments of the present application, an analytical expression for the triaxial stress affecting the propagation speed of the ultrasonic wave is given, which can characterize the influence of any triaxial stress on the propagation speed of the ultrasonic wave.

[0045] The photoelastic theory model in which triaxial stress affects the ultrasonic sound velocity is a physical model that describes the relationship between the elastic properties of a material under stress and the characteristics of acoustic wave propagation. The stress reconstruction coefficient matrix is a system matrix for the change in the propagation time of ultrasonic waves affected by triaxial stress.

[0046] In one possible implementation, as Figure 2 shown, the process of establishing the stress reconstruction coefficient matrix based on the photoelastic theory model in which triaxial stress affects the ultrasonic sound velocity mainly includes S201-S204.

[0047] S201. Derive the photoelastic theory model in which triaxial stress affects the ultrasonic sound velocity to obtain the calculation formula for the stress influence coefficient, and the calculation formula for the stress influence coefficient is used to reflect the influence of the triaxial stress change amount on the wave propagation time change amount.

[0048] Solve and derive the acoustoelastic theory model that the three - dimensional stress of metal affects the ultrasonic sound velocity using the simulation direction of the three - dimensional stress, and obtain the relationship between the change in wave propagation velocity and the change in three - dimensional stress; conduct derivation and transformation on the change in wave propagation velocity and the change in three - dimensional stress to obtain the relationship between the change in wave propagation time and the change in three - dimensional stress; among them, the relationship between the change in wave propagation time and the change in three - dimensional stress is as shown in formula (1):

[0049]

[0050] Among them,

[0051] Among them, Δt represents the change in wave propagation time, dσ represents the change in three - dimensional stress, represents the calculation formula of the stress influence coefficient, L i is the wave propagation distance, ρ 0 is the metal density without stress influence, V 0 is the longitudinal wave propagation velocity without stress influence, and K and S are determined by the material second - order moduli λ, μ, the material third - order moduli l, m, n, and the three - dimensional stress direction is determined by the wave propagation direction.

[0052] Specifically, solve and derive the acoustoelastic theory model that the three - dimensional stress of metal affects the ultrasonic sound velocity using the simulation direction of the three - dimensional stress, and obtain the relationship between the change in the propagation velocity of ultrasonic waves and the change in three - dimensional stress.

[0053] The propagation velocity of ultrasonic waves in a material with internal stress depends not only on the density and Lamé constants of the material, but also on the higher - order elastic constants and the initial stress state. This relationship between the propagation velocity of ultrasonic waves and the stress state is called the acoustoelastic effect. To describe different states of an object, three states are usually defined, namely the natural state, the initial state, and the final state. The descriptions of the three states in acoustoelastic theory are as Figure 3 shown. The natural state refers to the undeformed state of the object without stress and strain, and its position is represented by the vector ξ. The initial state refers to the state of the object under residual stress, and its position vector is represented by X. The final state refers to the state reached by superimposing a small acoustic perturbation on the deformed object, and its position vector is represented by x. All physical variables and material properties in the three states are represented by the superscripts o, i, f respectively. The deformation from the natural state to the initial state is u i =X - ξ, the deformation from the natural state to the final state is u f =x - ξ, and the deformation from the initial state to the final state is u = x - X.

[0054] The acoustoelastic theory model that the three - dimensional stress expressed in the initial coordinates affects the ultrasonic sound velocity is as shown in formula (2).

[0055]

[0056] In the formula, c IJKL is the equivalent stiffness represented by the initial coordinates, and c IJKL is the Lamé constant of the material, and c IJKLMN is the third-order elastic constant of the material, is the displacement in the initial state, X M is the component of the position vector in the initial state, is the component of the strain tensor in the initial state. is the Cauchy stress tensor in the initial state, and ρ i is the density in the initial state. The material under study is represented by the Murnaghan model, and its Lamé constant c IJKL is completely represented by the Lamé constants λ and μ, and the third-order elastic constant c IJKLMN is completely represented by l, m, and n.

[0057] According to the acoustoelastic equation derived with the initial coordinates, a program is written. Input the density ρ, λ, μ, l, m, and n of the material, the direction of the triaxial stress in the spatial coordinate system and the propagation direction of the ultrasonic wave in the spatial coordinate system, and the wave propagation velocity of the ultrasonic wave in the set wave propagation direction under the triaxial stress tensor can be solved.

[0058] Furthermore, an acoustoelastic theoretical model of the influence of the change in triaxial stress on the change in wave propagation time and the influence of triaxial stress on ultrasonic sound velocity is established. The derivation is based on the spatial coordinate system. The triaxial stress adopted is expressed in the form of a stress tensor. Since the triaxial stress tensor contains more unknowns, the stress tensor at each point is equivalently transformed into the stress state of each microelement represented by the principal stress and is represented by a triaxial stress vector in the local coordinate system.

[0059] The ultrasonic wave propagates inside the metal. Assume that the wave propagation direction of the ultrasonic wave in the spatial coordinate system is The setting of the coordinate system for the triaxial stress situation and the description of the simulation direction are as Figure 4 shown. The triaxial stress vector in the local coordinate system x 1 y 1 z 1 is represented as where σ is the amplitude of the triaxial stress vector, a is the projection coefficient of the triaxial stress vector on the x 1 axis, b is the projection coefficient of the triaxial stress vector on the y 1 axis, and c is the projection coefficient of the triaxial stress vector on the z 1 axis.

[0060] The wave propagation direction of the ultrasonic wave Representation of the triaxial stress vector in the local coordinate system Solve the photoelastic theory model (Equation 2) that describes the influence of triaxial stress in the initial coordinates on the ultrasonic sound velocity, and further take partial derivatives to obtain the relationship between the change in the ultrasonic wave propagation velocity and the change in triaxial stress, as shown in Equation (3).

[0061]

[0062] In Equation (3),

[0063] where σ is the triaxial stress vector, dσ is the change in triaxial stress, a, b, and c are the projection coefficients of the triaxial stress, L i is the ultrasonic wave propagation distance, ρ is the material density of the metal without stress influence, V 0 is the longitudinal wave propagation distance without stress influence, λ and μ are the Lamé constants, and l, m, and n are the third-order elastic constants. The projection coefficients of the triaxial stress are the projection coefficients of the triaxial stress vector in the local coordinate system x 1 y 1 z 1 among them.

[0064] The density ρ required in the above formula 0 , the ultrasonic wave propagation velocity V without stress influence 0 are determined by experiments using calibration parts without internal stress; the Lamé constants λ and μ can be fully determined by mechanical tensile tests, and l, m, and n are determined by experiments according to the formulas derived from the basic photoelastic equation. By conducting experiments on the propagation of Lcr waves parallel to the stress direction, transverse waves with the propagation direction perpendicular to the stress direction and the particle vibration direction parallel to the stress direction, and longitudinal waves propagating perpendicular to the stress direction, the relationships between the three sets of sound velocity changes and the uniaxial stress changes are obtained, and then l, m, and n are solved according to the photoelastic theory equation. The projection coefficients a, b, and c in the triaxial stress vector are determined by the simulation direction in the triaxial stress in S101.

[0065] To adapt to the subsequent inversion reconstruction algorithm, the relationship between dσ and dV L is further transformed into the relationship between the triaxial stress change dσ and the wave propagation time change dt.

[0066] Specifically, assume that the time taken for ultrasonic waves to propagate within a propagation distance L i is t, then its propagation velocity within this propagation distance is as shown in Equation (4).

[0067]

[0068] where L iis the wave propagation distance, t is the wave propagation time for this section of wave propagation distance, and V L is the wave propagation speed for this section of wave propagation distance.

[0069] Taking the derivative of the wave propagation speed of ultrasonic waves in formula (4) with respect to the wave propagation time t, formula (5) is obtained.

[0070]

[0071] Substituting formula (5) into formula (3) and approximately considering t = t 0 (the change in wave propagation time caused by stress is relatively small), the change in wave propagation time caused by triaxial stress within a certain wave propagation distance L i can be obtained as shown in formula (6).

[0072]

[0073] Formula (6) is the change in the wave propagation time of ultrasonic waves caused by triaxial stress within the wave propagation distance L i . For the problem of ultrasonic waves propagating along the wave propagation direction, with different amplitudes of triaxial stress distribution and a total propagation distance of L, the change in the wave propagation time of ultrasonic waves within the total time period is as shown in formula (7).

[0074]

[0075] Formula (7) is the relationship between the change in the wave propagation time of ultrasonic waves within the total time period and the change in triaxial stress.

[0076] Among them, represents the calculation formula of the stress influence coefficient.

[0077] S202. Discretize the metal area into N grid areas. Among them, N is greater than or equal to 2.

[0078] If you want to construct a cloud map of the triaxial stress field of the metal, you can pre-construct a region to be reconstructed.

[0079] The cloud map of the triaxial stress field of the metal can be described by a two-dimensional function, where x and y are the coordinates of spatial pixel points, and the value of the function corresponds to the value of the cloud map imaging, that is, the brightness of the image. The value of the function corresponds to the amplitude of the triaxial stress of the triaxial stress field in the known simulation direction.

[0080] In the embodiments of the present application, taking the region to be reconstructed as a square as an example, discretize the region to be reconstructed into N = n×n square grid areas, and each grid area is a pixel point. The discrete pixel density determines the accuracy of the image. The characterization image of the triaxial stress field of the measured metal is included within the reconstructed region. The region to be reconstructed can be understood as a custom region.

[0081] The general discretization of the area to be reconstructed and the projection area are as Figure 5 shown. The area to be reconstructed is discretized into 400 = 20×20 grid areas. The grid areas are numbered in sequence from left to right and from bottom to top, thus forming the required imaging area.

[0082] S203. Calculate the stress influence coefficients of M sound beam paths in each grid area based on the calculation formula of the stress influence coefficient.

[0083] The transmission of sound beam through metal refers to the process of ultrasonic wave propagating in metal materials. This process involves the ultrasonic wave entering the metal material from the excitation position, and after transmission inside the metal, the received signal is captured by the probe at the receiving position.

[0084] Preset the excitation position and receiving position of the ultrasonic wave in advance, and then determine M sound beam paths. Calculate the wave propagation distance of each sound beam path in each grid area when the sound beam path transmits through the metal.

[0085] The wave propagation distance in each grid area refers to the wave propagation distance in each grid area when the excitation signal transmits through the metal material, as Figure 5 shown in. When the sound beam path i transmits through the metal material, the distance passed in the grid area j.

[0086] In a possible implementation, calculate the stress influence coefficients of M sound beam paths in each grid area based on the calculation formula of the influence coefficient, including: preset multiple excitation positions and multiple receiving positions, and determine M sound beam paths based on the multiple excitation positions and multiple receiving positions, where the multiple excitation positions are set in different directions of the area to be reconstructed, and the multiple receiving positions are set in different directions of the area to be reconstructed; for each sound beam path among the M sound beam paths, calculate the wave propagation distance of the sound beam path in each grid area; calculate the stress influence coefficients of the sound beam path in each grid area based on the calculation formula of the stress influence coefficient, the material properties of the superalloy, and the wave propagation distance in each grid area.

[0087] In the embodiment of the present application, with the midpoint of the area to be reconstructed as the midpoint, multiple excitation positions are distributed on a circular ring centered on this midpoint. This circular ring is in the same plane as the area to be reconstructed, and the distances between multiple excitation positions are the same. In other words, multiple excitation positions are distributed at different positions in the period of the area to be reconstructed. Similarly, multiple receiving positions are distributed on a circular ring centered on this midpoint. This circular ring is in the same plane as the area to be reconstructed, and the distances between multiple receiving positions are the same. In other words, multiple receiving positions are distributed at different positions in the period of the area to be reconstructed.

[0088] Since the acoustic beam is emitted from the excitation position and received at the reception position, M acoustic beam paths can be distributed at each position in the region to be reconstructed.

[0089] As can be seen from the description in the above embodiments, after the excitation position and the reception position are determined, according to the fact that two points determine a straight line, the expression of the acoustic beam path is calculated, and the expression of the acoustic beam path is transformed into the coordinate system of the region to be reconstructed. Since the coordinates of each grid region in the region to be reconstructed are determined, the intersection points of the acoustic beam path and the boundaries of each grid region are calculated. For a grid region, the distance between the two intersection points of the borders is used as the wave propagation distance of the acoustic beam path within the grid region.

[0090] Specifically, according to the excitation position and the reception position of the ultrasonic wave, their coordinates are transformed into the coordinates of the region to be reconstructed.

[0091] The wave propagation distances of M acoustic beam paths in each grid region are calculated, which are the wave propagation distances L in the calculation formula of the stress influence coefficient. i Furthermore, for the wave propagation distance within each grid region, the wave propagation distance within the grid region is multiplied by the coefficient of the change in the wave propagation time affected by the triaxial stress within each grid region. This is the stress influence coefficient of the grid region.

[0092] Among them, the calculation methods and meanings of K, S, and V 0 , ρ 0 can be referred to the description in the above embodiments, and will not be elaborated specifically in the embodiments of the present application.

[0093] S204. Integrate the stress influence coefficients of M acoustic beam paths in each grid region respectively to obtain an M×N-dimensional stress reconstruction coefficient matrix.

[0094] Let the coefficient of the change in the wave propagation time affected by the triaxial residual stress of the i-th acoustic beam path in the j-th regional grid be w ij , and M is the total number of acoustic beam paths. Then the stress reconstruction coefficient matrix is an M×N-dimensional matrix composed of w ij .

[0095] So far, an M×N-dimensional stress reconstruction coefficient matrix is obtained.

[0096] S103. Collect the change in the wave propagation time when M acoustic beams transmit through the metal.

[0097] The transmission of the acoustic beam path through the metal refers to the process of ultrasonic wave propagation in the superalloy material. This process involves the ultrasonic wave entering the superalloy from the excitation position and being captured by the probe at the reception position as a received signal after a series of reflections, refractions, and attenuations inside it.

[0098] The change in wave propagation time refers to the change in the propagation time of a wave (such as a sound wave, ultrasonic wave, etc.) when it propagates in a metal due to the change in the internal stress state of the medium.

[0099] For each sound beam path, there is a corresponding change in wave propagation time. For M sound beam paths, M changes in wave propagation time can be obtained. In the embodiments of the present application, the change in the wave propagation time difference formed by a single sound beam path is taken as an example for illustration.

[0100] In a possible implementation, collecting the change in wave propagation time when M sound beams transmit through the metal includes: for each of the M sound beam paths, obtaining the wave propagation time when the sound beam path transmits through the metal without stress influence; obtaining the wave propagation time when the sound beam path transmits through the metal under triaxial stress influence; subtracting the wave propagation time under triaxial stress influence from the wave propagation time without stress influence to obtain the change in wave propagation time corresponding to the sound beam path under triaxial stress influence.

[0101] The absence of stress influence can be understood as that when performing ultrasonic detection, there is no additional mechanical stress or residual stress in the metal. This is usually under the ideal condition that the superalloy is in a free state and not subjected to external forces. The excitation signal refers to the ultrasonic wave emitted by the ultrasonic probe into the superalloy. The ultrasonic wave can be a high-frequency vibration within a short time, and its frequency, amplitude, and shape can be selected according to specific detection requirements.

[0102] The wave propagation time can be obtained by any of the following methods: cross-correlation analysis method, Hilbert transform method, zero-crossing method, etc. Among them, the cross-correlation analysis method determines the time delay between the excitation signal and the received signal by calculating the similarity between the excitation signal and the received signal. The zero-crossing method determines the time delay by detecting the moment when the received signal crosses the zero level. The Hilbert transform method obtains the analytic signal by performing the Hilbert transform on the received signal, and then determines the time delay according to the envelope of the analytic signal.

[0103] In the embodiments of the present application, the process of calculating the wave propagation time by the cross-correlation analysis method is introduced.

[0104] The method for calculating the wave propagation time without stress influence includes: obtaining the first received signal and the excitation signal of the sound beam path without stress influence; performing cross-correlation analysis on the excitation signal and the first received signal to obtain the propagation time of the ultrasonic wave without stress influence.

[0105] The first received signal refers to the transmitted signal received by the probe without stress influence. The superalloy is set to be in a stress-free state, and appropriate frequency and pulse width are selected according to the required detection depth and resolution, and an appropriate voltage is applied to generate the required excitation signal. The excitation signal is transmitted through the superalloy, and an obvious signal received by the probe at the receiving position is the first received signal.

[0106] Cross-correlation analysis is a technique used in ultrasonic testing to accurately measure the propagation time. Cross-correlation analysis is used to measure the degree of similarity between the excitation signal and the first received signal, especially the time delay between the excitation signal and the first received signal.

[0107] Obtain the waveforms of the excitation signal and the first received signal, including their frequency, amplitude, and shape, etc. Perform necessary preprocessing on the excitation signal and the first received signal, such as denoising, filtering, and smoothing, to improve the accuracy of subsequent analysis.

[0108] Convert the excitation signal and the first received signal into digital signals, use software tools to perform cross-correlation operations on the excitation signal and the received signal, find the maximum point of the cross-correlation function, and the time offset corresponding to this point is the wave propagation time between the excitation signal and the first received signal.

[0109] A method for calculating the wave propagation time affected by triaxial stress includes: obtaining the second received signal and the excitation signal of the sound beam path under the influence of triaxial residual stress, and performing cross-correlation analysis on the excitation signal and the second received signal to obtain the propagation time of the ultrasonic wave under the influence of triaxial residual stress.

[0110] The superalloy is set to be in a state of triaxial residual stress, and the excitation signal with the same waveform is transmitted through the superalloy. An obvious signal received by the probe at the receiving position is the second received signal.

[0111] The calculation method of the wave propagation time between the excitation signal and the second received signal is the same as that of the wave propagation time between the excitation signal and the first received signal. For details, reference can be made to the description in the above embodiments, and the embodiments of the present application will not be elaborated here.

[0112] Subtract the calculated wave propagation time between the excitation signal and the second received signal under the influence of triaxial stress from the calculated wave propagation time between the excitation signal and the first received signal without stress influence to obtain the difference between the two, which is the change amount of the wave propagation time of a single sound beam path under the influence of triaxial residual stress.

[0113] For M sound beam paths, the above wave propagation time change amount calculation method is adopted to calculate the corresponding wave propagation time change amounts respectively, and M wave propagation time change amounts are obtained. Among them, the wave propagation time change amount is represented by p, p iIndicates the change in wave propagation time corresponding to the i-th acoustic beam path, where i is greater than or equal to 1 and less than or equal to M.

[0114] S104. Perform reconstruction and solution based on the stress reconstruction coefficient matrix and the change in wave propagation time to obtain the amplitudes of the three-dimensional stresses.

[0115] After discretizing the data of the three-dimensional stress nephogram, the reconstruction problem essentially becomes solving the equation p = Ax. Here, A is the stress reconstruction coefficient matrix, which is determined by the propagation distances of each acoustic beam path passing through each grid region under each assumption; x is the amplitude matrix of the three-dimensional residual stress, and x i is the amplitude of the three-dimensional stress to be reconstructed within each grid region, and p is the matrix of the changes in wave propagation times of M waves.

[0116] An iterative reconstruction algorithm is used to solve the amplitude matrix x of the three-dimensional residual stress. Based on the iterative reconstruction algorithm, a basic one can be developed. Its core idea is to make the estimated image satisfy the iterative equation during each image update. The algebraic reconstruction algorithm only uses the change in wave propagation time of a single acoustic beam path in each iteration to update the amplitudes of the three-dimensional stresses corresponding to the grid regions passed through by this ray. The iterative reconstruction process of the amplitudes of the three-dimensional stresses by the algorithm is as Figure 6 shown.

[0117] The following introduces the solution process of the amplitude matrix x of the three-dimensional residual stress.

[0118] S301. Obtain the initial values of the amplitudes of the three-dimensional stresses within j grid regions

[0119] S302. Calculate the change in wave propagation time of the i-th acoustic beam path within the metal region

[0120] S303. Calculate the correction value corresponding to the j-th grid region

[0121] S304. Correct the amplitudes of the three-dimensional stresses in the j-th grid region to obtain the corrected amplitudes of the three-dimensional stresses

[0122]

[0123] S305. Let i equal i plus 1.

[0124] S306. Determine whether i is less than or equal to M. If so, return to execute the steps of S302; if not, execute S307.

[0125] S307. Calculate the corrected amplitudes of the three-dimensional stresses The second derivative of the grid boundary length.

[0126] S308. Determine whether the second derivative is less than a set threshold. If so, execute S310; if not, execute S309.

[0127] S309. Perform dynamic smoothing on each row or column of the grid and then return to execute S301.

[0128] S310. Determine If not, then return to execute S301. If so, execute S311.

[0129] S311. Use the corrected three - dimensional stress amplitude as the output.

[0130] After solving according to the above steps, the amplitude matrix x of the three - dimensional stress can be obtained.

[0131] S105. Perform three - dimensional stress field imaging based on the three - dimensional stress direction and the three - dimensional stress amplitude.

[0132] After obtaining the amplitude matrix of the imaged three - dimensional stress, multiply it by the simulated direction of the three - dimensional stress obtained from the thermodynamic simulation to obtain the nephogram of the three - dimensional stress of the metal, that is, the nephogram of the axial, circumferential, and radial three - dimensional stresses of the metal.

[0133] In the embodiment of the present application, a linearized analytical expression between the change in the wave propagation time of ultrasonic waves and the change in the three - dimensional stress is established, and the three - dimensional residual stress of the metal is characterized based on the iterative reconstruction algorithm. A method for inverse characterization of the three - dimensional residual stress of the metal based on ultrasonic measurement is proposed, which realizes the reconstruction of the three - dimensional residual stress field of the metal when the three - dimensional stress direction obtained by thermal simulation is known. When the three - dimensional residual stress direction is known, based on the acousto - elastic theory model in which the three - dimensional stress affects the ultrasonic sound velocity and the internal definition representation method of the part, the coefficients of the change in the wave propagation time and the change in stress under each pixel in the area to be characterized are obtained through coordinate transformation, and the influence coefficient matrix required for stress characterization is constructed. Combine the influence coefficient matrix and the change in the wave propagation time of multiple sound beam paths of the metal collected under the influence of the three - dimensional residual stress to construct the equation to be solved, and form an inverse characterization method of the residual stress based on the iterative reconstruction algorithm.

[0134] In a specific implementation scenario, taking a superalloy columnar bar as an example, the quenching residual stress of the superalloy can be predicted through thermodynamic finite - element simulation, and the distribution of its internal quenching residual stress field is obtained as Figure 7 shown, and then the initial state of the superalloy under the influence of the quenching residual stress is obtained as the input for ultrasonic simulation measurement. Figure 7 (a) shows the radial stress distribution in the quenching residual stress of the bar, Figure 7 (b) shows the circumferential stress distribution in the quenching residual stress of the bar Figure 7(c) is the axial stress distribution in the residual stress of the bar after quenching.

[0135] Subsequently, the corresponding wave propagation time is measured by ultrasonic, and then the corresponding triaxial residual stress amplitude is inversely output according to the inversion method proposed in the embodiments of the present application.

[0136] Running the simulation according to the above settings, the simulation results in the stress-free state can be obtained as shown in Figure 8 (a), and the simulation results in the state with residual stress are as shown in Figure 8 (b). It can be seen that longitudinal waves, transverse waves and surface waves are excited both in the case of no stress and in the case of residual stress. The ultrasonic waves propagating in the structure include longitudinal waves, transverse waves, head waves and surface waves propagating along the boundary. Among them, the longitudinal wave has the maximum wave velocity and reaches each monitoring point first, followed by the head wave, and the surface wave has the minimum wave velocity. The ultrasonic wave used to calculate the wave propagation time is the longitudinal wave.

[0137] Extract the velocities of the ultrasonic waves in the x and y directions, synthesize the corresponding velocity vectors, and project them in the direction of the vector formed by the excitation point position to the monitoring point position, then the ultrasonic reception signal propagating from the excitation point position to the monitoring point position can be obtained.

[0138] For z points, each point is sequentially selected as the excitation point, an excitation signal is emitted at the excitation point, and signals are received at other points except the excitation point, so as to obtain an omnidirectional excitation signal and a reception signal, and then the change amount of the wave propagation time of the ultrasonic wave under the influence of stress in multiple directions and multiple acoustic beam paths can be obtained.

[0139] Collect the corresponding results at different points, and obtain the corresponding change amount of the wave propagation time through cross-correlation analysis.

[0140] According to the multi-transmission and multi-reception results obtained by the aforementioned ultrasonic measurement, the internal residual stress of the cylindrical structure is characterized. The original residual stress field distribution of the result to be reconstructed is as shown in Figure 7 . The required imaging area is divided into a 100×100 grid, and the imaging resolution is 1 mm. The coefficient matrix constructed by the internal stress algebraic reconstruction algorithm has a total of 72×43 = 3096 rows and a total of 10000 columns. The convergence condition is set that the change rate in 10 consecutive generations is less than 1%, and the residual stress optimization reaches convergence at the 18th generation during the calculation and solution.

[0141] The results of the triaxial stress field obtained by inversion are as shown in Figure 9 . Figure 9 (a) is the reconstruction result of the radial residual stress of the bar, Figure 9 (b) is the reconstruction result of the circumferential residual stress of the bar, Figure 9(c) shows the results of the reconstruction of the axial residual stress of the bar. The three-dimensional stress field can be reconstructed well, and the relative error of the maximum stress value of the three-dimensional stress is less than 25%. It can be seen that the stress amplitude of the specific three-dimensional stress field can be reconstructed well, and the order of magnitude of the three-dimensional stress value of the metal can be obtained by this method. Considering the distribution characteristics of the residual stress, certain lateral and longitudinal smoothing constraints are imposed on the continuity of the grid in the inversion method, that is, sudden oscillations or sharp positive and negative alternations are not allowed in each row and column of the grid. Therefore, some lateral artifacts appear in the inversion results.

[0142] In the actual production process, the machined parts often undergo further vibration treatment or aging treatment to reduce the internal residual stress of the parts. Therefore, the effect of the method for reducing residual stress can be judged by detecting the parts before treatment and after treatment. At the same time, the amplitude of the three-dimensional stress inside the parts can be characterized by measuring multiple sound beam paths through ultrasonic measurement, and this can be used as the corresponding reference. Furthermore, when preparing new parts, the stress inversion characterization is carried out by measuring the change amount of the wave propagation time results, and the characterization results are compared with the reference results to judge whether the newly prepared parts meet the standards numerically.

[0143] It can be seen from the inversion results that according to the proposed method for characterizing the residual stress of the bar based on the iterative reconstruction algorithm, except for the stress amplitude range, the contour distribution of the stress can be reconstructed well. Further, the contour range of the stress characterization results is statistically analyzed to evaluate the accuracy of the position and region of the characterization results, and the inversion results of the core part are highly effective.

[0144] Figure 10 This is a schematic structural diagram of a device for imaging the three-dimensional stress field of a metal based on ultrasonic measurement in the embodiments of the present application. As Figure 10 shown, the device 100 for imaging the three-dimensional stress field of a metal based on ultrasonic measurement provided in the embodiments of the present application mainly includes: a stress direction acquisition module 101, a coefficient matrix establishment module 102, a wave propagation time change amount acquisition module 103, a three-dimensional stress amplitude calculation module 104, and a three-dimensional stress imaging module 105.

[0145] Among them, the stress direction acquisition module 101 is used to obtain the simulation direction of the three-dimensional stress of the metal through simulation; the coefficient matrix establishment module 102 is used to establish a stress reconstruction coefficient matrix based on the acoustoelastic theory model in which the three-dimensional stress affects the ultrasonic sound velocity; the wave propagation time change amount acquisition module 103 is used to acquire the change amount of the wave propagation time when M sound beams transmit through the metal; the three-dimensional stress amplitude calculation module 104 is used to perform reconstruction and solution based on the stress reconstruction coefficient matrix and the change amount of the wave propagation time to obtain the amplitude of the three-dimensional stress; the three-dimensional stress imaging module 105 is used to perform three-dimensional stress field imaging based on the simulation direction of the three-dimensional stress and the amplitude of the three-dimensional stress.

[0146] In a possible implementation manner, the stress direction acquisition module 101 is specifically configured to establish a thermodynamic simulation model of the metal based on preset thermodynamic parameters, material properties, and boundary settings; and perform a simulation on the heat treatment process of the metal based on the thermodynamic simulation model of the metal to obtain the simulation direction of the triaxial stress of the metal.

[0147] In a possible implementation manner, the coefficient matrix establishment module 102 is specifically configured to derive an acoustoelastic theory model of the influence of triaxial stress on ultrasonic sound velocity to obtain a calculation formula for the stress influence coefficient, where the calculation formula for the stress influence coefficient is used to reflect the influence of the triaxial stress change amount on the wave propagation time change amount; discretize the region to be reconstructed into N grid regions; calculate the stress influence coefficients of M sound beam paths in each grid region based on the calculation formula for the stress influence coefficient; and integrate the stress influence coefficients of M sound beam paths in each grid region to obtain an M×N-dimensional stress reconstruction coefficient matrix.

[0148] In a possible implementation manner, the coefficient matrix establishment module 102 is specifically configured to solve and derive an acoustoelastic theory model of the influence of triaxial stress on ultrasonic sound velocity by using the simulation direction of the triaxial stress of the metal to obtain a relational expression between the wave propagation velocity change amount and the triaxial stress change amount; perform a derivation transformation on the relational expression between the wave propagation velocity change amount and the triaxial stress change amount to obtain a relational expression between the wave propagation time change amount and the triaxial stress change amount; where the relational expression between the wave propagation time change amount and the triaxial stress change amount is as follows:

[0149]

[0150] where, Δt represents the wave propagation time change amount, dσ represents the triaxial stress change amount, represents the calculation formula for the stress influence coefficient, L i is the wave propagation distance, ρ 0 is the metal density without stress influence, V 0 is the wave propagation velocity, and K and S are determined by the material second-order moduli λ, μ, the material third-order moduli l, m, n, and the triaxial stress direction is determined by the wave propagation direction.

[0151] In a possible implementation, the coefficient matrix building module 102 is specifically configured to preset a plurality of excitation positions and a plurality of receiving positions in advance, and determine M sound beam paths based on the plurality of excitation positions and the plurality of receiving positions, where the plurality of excitation positions are arranged in different directions of the area to be reconstructed, and the plurality of receiving positions are arranged in different directions of the area to be reconstructed; for each of the M sound beam paths, calculate the wave propagation distance of the sound beam path in each grid area; based on the calculation formula of the stress influence coefficient, the material properties of the superalloy, and the wave propagation distance in each grid area, calculate the stress influence coefficient of the sound beam path in each grid area.

[0152] In a possible implementation, the wave propagation time change amount acquisition module 103 is specifically configured to, for each of the M sound beam paths, obtain the wave propagation time when the sound beam path transmits through the metal without stress influence; obtain the wave propagation time when the sound beam path transmits through the metal under the influence of triaxial stress; subtract the wave propagation time under the influence of triaxial stress from the wave propagation time without stress influence to obtain the wave propagation time change amount corresponding to the sound beam path under the influence of triaxial stress.

[0153] In a possible implementation, the triaxial stress amplitude calculation module 104 is specifically configured to use an iterative reconstruction algorithm to reconstruct and solve the following equation to obtain the amplitude of the triaxial stress,

[0154] p = Ax;

[0155] where p is an M×1 wave propagation time change amount matrix, A is an M×N-dimensional stress reconstruction coefficient matrix, and x is an N×1-dimensional triaxial stress amplitude matrix.

[0156] The metal triaxial stress field imaging device based on ultrasonic measurement provided by the embodiments of the present application can execute the metal triaxial stress field imaging method provided by any embodiment of the present invention, and has the corresponding functional modules and beneficial effects for executing the method.

[0157] Figure 11 It is a schematic structural diagram of an electronic device provided in this embodiment. The electronic device may include a metal triaxial stress field imaging device based on ultrasonic measurement, as Figure 11 shown, the electronic device 1100 includes a processor 1110, a memory 1120, an input device 1130, and an output device 1140; the number of processors 1110 in the electronic device may be one or more, Figure 11 taking one processor 1110 as an example; the processor 1110, the memory 1120, the input device 1130, and the output device 1140 in the electronic device may be connected through a bus or other means, Figure 11Take the bus connection as an example.

[0158] The memory 1120, as a computer-readable storage medium, can be used to store software programs, computer-executable programs, and modules, such as the program instructions / modules corresponding to the metal three-way residual stress imaging method in the embodiments of the present invention. The processor 1110 executes various functional applications and data processing of the electronic device by running the software programs, instructions, and modules stored in the memory 1120, that is, implements the metal three-way stress field imaging method based on ultrasonic measurement provided by the embodiments of the present invention.

[0159] The memory 1120 may mainly include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created according to the use of the terminal, etc. In addition, the memory 1120 may include high-speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state storage devices. In some instances, the memory 1120 may further include a memory remotely provided with respect to the processor 1110, and these remote memories can be connected to the electronic device through a network. Examples of the above network include but are not limited to the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0160] The input device 1130 can be used to receive input digital or character information, and generate key signal inputs related to the user settings and function controls of the electronic device, and may include a keyboard, a mouse, etc. The output device 1140 may include a display device such as a display screen.

[0161] This embodiment also provides a storage medium containing computer-executable instructions, and the computer-executable instructions are used to implement the metal three-way stress field imaging method based on ultrasonic measurement provided by the embodiments of the present invention when executed by a computer processor.

[0162] Certainly, the computer-executable instructions of a storage medium containing computer-executable instructions provided by the embodiments of the present invention are not limited to the method operations as described above, and can also execute related operations in the metal three-way stress field imaging method based on ultrasonic measurement provided by any embodiment of the present invention.

[0163] From the above description of the embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software and necessary general-purpose hardware. Of course, it can also be implemented by hardware, but in many cases, the former is a better implementation. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a floppy disk, read-only memory (ROM), random access memory (RAM), flash memory (FLASH), hard disk, or optical disc of a computer, etc., including several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments of the present invention.

[0164] It should be noted that in the above embodiments of the metal triaxial stress field imaging device based on ultrasonic measurement, the various units and modules included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of the functional units are only for the convenience of mutual distinction and do not limit the protection scope of the present invention.

[0165] It should be noted that in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0166] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A metal three-dimensional stress field imaging method based on ultrasonic measurement, characterized in that: The method comprises: The simulation direction of the three-dimensional stress of the metal is obtained through simulation; The stress reconstruction coefficient matrix is ​​established based on the acoustic elasticity theoretical model of the effect of three-dimensional stress on ultrasonic sound velocity; Collecting the change in wave propagation time when M sound beams penetrate the metal; Reconstruct and solve based on the stress reconstruction coefficient matrix and the wave propagation time variation to obtain the amplitude of the three-dimensional stress; Three-dimensional stress field imaging is performed based on the simulation directions of the three-dimensional stresses and the amplitudes of the three-dimensional stresses.

2. The method according to claim 1, characterized in that The simulation direction of the three-dimensional stress of the metal obtained by simulation includes: Establish a thermodynamic simulation model of metals based on pre-set thermodynamic parameters, material properties and boundary settings; Based on the thermodynamic simulation model of the metal, the heat treatment process of the metal is simulated to obtain the simulation direction of the three-dimensional stress of the metal.

3. The method according to claim 1, characterized in that The stress reconstruction coefficient matrix is ​​established based on the acoustic elasticity theoretical model of the influence of three-dimensional stress on ultrasonic sound velocity, including: The acoustic elasticity theory model of the influence of three-dimensional stress on ultrasonic sound velocity is derived to obtain a calculation formula of the stress influence coefficient, which is used to reflect the influence of the change of the three-dimensional stress on the change of the wave propagation time; Discretize the area to be reconstructed into N grid areas; Based on the calculation formula of the stress influence coefficient, the stress influence coefficient of the M sound beam paths in each grid area is calculated; The stress influence coefficients of the M acoustic beam paths in each grid area are respectively integrated to obtain an M×N dimensional stress reconstruction coefficient matrix.

4. The method according to claim 3, characterized in that By transforming the coordinate system, the acoustic elasticity theoretical model of the influence of three-dimensional stress on ultrasonic sound velocity is derived to obtain the calculation formula of the stress influence coefficient, including: The simulation direction of the metal three-dimensional stress is used to solve and derive the acoustic elasticity theory model of the three-dimensional stress affecting the ultrasonic sound velocity, and the relationship between the change in wave propagation velocity and the change in the three-dimensional stress is obtained; Derivation and transformation of the relationship between the wave propagation velocity variation and the three-dimensional stress variation are performed to obtain the relationship between the wave propagation time variation and the three-dimensional stress variation; The relationship between the change in wave propagation time and the change in three-dimensional stress is as follows: in, Δt represents the change in the wave propagation time, dσ represents the change in the three-dimensional stress, The calculation formula for stress influence coefficient, L i is the wave propagation distance, ρ0 is the density of the high-temperature alloy without stress, V0 is the longitudinal wave propagation velocity without stress, K and S are determined by the second-order modulus λ and μ of the material and the third-order modulus l, m, and n of the material.

5. The method according to claim 4, characterized in that Based on the calculation formula of the stress influence coefficient, the stress influence coefficient of the M sound beams in each grid area is calculated, including: Presetting a plurality of excitation positions and a plurality of receiving positions, and determining M sound beam paths based on the plurality of excitation positions and the plurality of receiving positions, wherein the plurality of excitation positions are arranged in different directions of the area to be reconstructed, and the plurality of receiving positions are arranged in different directions of the area to be reconstructed; For each of the M paths of the sound beams, calculating a wave propagation distance of the path of the sound beam in each grid area; Based on the calculation formula of the stress influence coefficient, the material property and the wave propagation distance in each grid area, the stress influence coefficient of the acoustic beam path in each grid area is calculated.

6. The method according to claim 1, characterized in that The collecting of the change in wave propagation time when the M ultrasonic sound beams penetrate the metal includes: For each of the M acoustic beam paths, obtaining a wave propagation time when the acoustic beam penetrates the metal without stress; Acquire the wave propagation time when the sound beam penetrates the metal under the influence of the triaxial stress; The wave propagation time under the influence of the three-dimensional stress is subtracted from the wave propagation time under the influence of no stress, so as to obtain the change of the wave propagation time corresponding to the acoustic beam under the influence of the three-dimensional stress.

7. The method according to claim 1, characterized in that The reconstructing and solving based on the stress reconstruction coefficient matrix and the wave propagation time variation to obtain the amplitude of the three-dimensional stress includes: The iterative reconstruction algorithm is used to solve the following equations to obtain the amplitudes of the three-dimensional stresses: p = Ax; Among them, p is the M×1 matrix of wave propagation time variation, A is the M×N dimensional stress reconstruction coefficient matrix, and x is the N×1 dimensional three-dimensional stress amplitude matrix.

8. A metal three-dimensional stress field imaging device based on ultrasonic measurement, characterized in that: The device comprises: A stress direction acquisition module is used to obtain the simulation direction of the three-dimensional stress of the metal through simulation; A coefficient matrix building module is used to build a stress reconstruction coefficient matrix based on the acoustic elasticity theory model of the influence of three-dimensional stress on ultrasonic sound velocity; A wave propagation time variation collection module, used for collecting the wave propagation time variation when M sound beams penetrate the metal; A three-dimensional stress amplitude calculation module is used to perform reconstruction and solution based on the stress reconstruction coefficient matrix and the wave propagation time variation to obtain the amplitude of the three-dimensional stress; The three-dimensional stress imaging module is used to perform three-dimensional stress field imaging based on the simulation direction of the three-dimensional stress and the amplitude of the three-dimensional stress.

9. An electronic device, characterized in that: The device comprises: one or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the metal triaxial stress field imaging method based on ultrasonic measurement as described in any one of claims 1 to 7.

10. A storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method for metal three-dimensional stress field imaging based on ultrasonic measurement as described in any one of claims 1 to 7 is implemented.

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