Method, apparatus and device for imaging a three-dimensional stress field of a metal based on ultrasonic measurements

Abstract

The application relates to the technical field of data processing, and particularly provides a metal three-way stress field imaging method, device and equipment based on ultrasonic measurement, which comprises the following steps: obtaining a simulation direction of metal three-way stress through simulation; establishing a stress reconstruction coefficient matrix based on an acoustic elasticity theoretical model of three-way stress affecting ultrasonic velocity; collecting a wave propagation time variation quantity when M sound beams transmit through the metal; and performing reconstruction solving based on the stress reconstruction coefficient matrix and the wave propagation time variation quantity to obtain a three-way stress amplitude. Three-way stress field imaging is performed based on the simulation direction of the three-way stress and the three-way stress amplitude, so that the distribution of the metal three-way stress field can be characterized.

Description

Technical Field

[0001] This application relates to the field of data processing technology, and in particular to a method, apparatus, device and medium for imaging triaxial stress fields of metals based on ultrasonic measurement. Background Technology

[0002] A triaxial stress field refers to the state in which a metallic material is simultaneously subjected to stresses in three mutually perpendicular directions. Triaxial stress can be caused by external loads during manufacturing or use, or it can be an internal self-balancing stress state without significant external loads. The internal self-balancing stress state without significant external loads is called residual stress. When a metallic part with residual stress is subjected to external loads under operating conditions, the externally applied stress and the internal residual stresses are superimposed, forming the actual triaxial stress field.

[0003] Residual stress is inevitably introduced into metal parts during manufacturing processes such as machining and heat treatment. This residual stress significantly impacts the dimensional accuracy, dimensional stability, and fatigue performance of metal parts, potentially leading to fatigue crack propagation, deformation, or even failure, thus affecting their service performance. Therefore, accurately characterizing the triaxial stress field of metals is a crucial research topic.

[0004] Currently, methods for characterizing the stress field of metals are mainly divided into two categories: destructive and non-destructive methods. Destructive methods release local residual stress in metal parts through mechanical means, thereby obtaining the local stress characteristics at the sampling point. However, this method cannot extrapolate the residual stress distribution at other locations on the metal part, and the metal part is damaged after testing and cannot be reused. Non-destructive methods do not damage metal parts. Current non-destructive methods generally start from the response of metal parts to ultrasonic excitation, using inversion studies to evaluate the residual stress level on or near the surface of the metal part, without causing damage. However, current methods for characterizing stress in metal parts are limited to local or near-surface areas, and there is an urgent need to develop new non-destructive methods for characterizing triaxial stress applicable to the interior of parts. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a method, apparatus, device, and medium for imaging the triaxial stress field of metals based on ultrasonic measurement, enabling the reconstruction of the triaxial stress field inside the metal.

[0006] In a first aspect, this application provides a method for imaging a triaxial stress field of metal based on ultrasonic measurement. The method includes: obtaining the simulated direction of the triaxial stress of the metal through simulation; establishing a stress reconstruction coefficient matrix based on the acoustoelastic theoretical model of the effect of triaxial stress on ultrasonic velocity; acquiring the wave propagation time change when M sound beams penetrate the metal; reconstructing and solving based on the stress reconstruction coefficient matrix and the wave propagation time change to obtain the amplitude of the triaxial stress; and performing triaxial stress field imaging based on the simulated direction of the triaxial stress and the amplitude of the triaxial stress.

[0007] Secondly, this application provides a metal triaxial stress field imaging device based on ultrasonic measurement. The device includes: a stress direction acquisition module for obtaining the simulated direction of the triaxial stress of the metal through simulation; a coefficient matrix establishment module for establishing a stress reconstruction coefficient matrix based on the acoustoelastic theoretical model of the influence of triaxial stress on ultrasonic velocity; a wave propagation time change acquisition module for acquiring the wave propagation time change when M sound beams penetrate the metal; a triaxial stress amplitude calculation module for reconstructing and solving based on the stress reconstruction coefficient matrix and the wave propagation time change to obtain the amplitude of the triaxial stress; and a triaxial stress imaging module for performing triaxial stress field imaging based on the simulated direction of the triaxial stress and the amplitude of the triaxial stress.

[0008] Thirdly, this application provides an electronic device including a metal triaxial stress field imaging device based on ultrasonic measurement, the device comprising: one or more processors; a storage device for storing one or more programs; and when the one or more programs are executed by the one or more processors, causing the one or more processors to implement the metal triaxial stress field imaging method based on ultrasonic measurement as described in the first aspect above.

[0009] Fourthly, this application provides a storage medium, which may be a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the metal triaxial stress field imaging method based on ultrasonic measurement as described in the first aspect above.

[0010] Fifthly, embodiments of this application provide a computer program product comprising a computer program or instructions that, when executed by a processor, implement the metal triaxial stress field imaging method based on ultrasonic measurement as described in any of the first aspects above.

[0011] This application provides a method, apparatus, device, and storage medium for imaging the triaxial stress field of a metal based on ultrasonic measurement. The main components include: obtaining the simulated direction of the triaxial stress in the metal through simulation; establishing a stress reconstruction coefficient matrix based on the acoustoelastic theory model of the effect of triaxial stress on ultrasonic velocity; acquiring the wave propagation time changes when M sound beams penetrate the metal; reconstructing and solving the triaxial stress amplitude based on the stress reconstruction coefficient matrix and the wave propagation time changes; and performing triaxial stress field imaging based on the reaction direction of the triaxial stress and the triaxial stress amplitude. This enables the characterization of the distribution of the triaxial residual stress field in the metal. Attached Figure Description

[0012] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 A schematic flowchart of a metal triaxial stress field imaging method based on ultrasonic measurement provided in this application embodiment;

[0015] Figure 2 A flowchart illustrating the calculation of the stress reconstruction coefficient matrix provided in an embodiment of this application;

[0016] Figure 3 A schematic diagram illustrating three states of acoustoelasticity theory provided in the embodiments of this application;

[0017] Figure 4 A schematic diagram showing the coordinate system setup and orientation for triaxial stress scenarios provided in this application embodiment;

[0018] Figure 5 This is a schematic diagram of the grid discretization of the region to be reconstructed provided in an embodiment of this application;

[0019] Figure 6 A flowchart illustrating the iterative reconstruction algorithm provided in the embodiments of this application;

[0020] Figure 7 A schematic diagram showing the distribution of residual stress in the cross-section of a bar during thermal simulation, as provided in the embodiments of this application.

[0021] Figure 8 A schematic diagram of the simulated ultrasonic wave field in a circular cross-section provided in an embodiment of this application;

[0022] Figure 9 A schematic diagram of residual stress field reconstruction imaging of a bar based on an iterative reconstruction algorithm, provided as an embodiment of this application;

[0023] Figure 10 A schematic diagram of the structure of a metal triaxial stress field imaging device based on ultrasonic measurement provided in an embodiment of this application;

[0024] Figure 11 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0025] To better understand the above-mentioned objectives, features, and advantages of this application, the solution of this application will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

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

[0027] The term "comprising" and its variations as used herein are open-ended inclusions, meaning "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". Definitions of other terms will be given in the description below.

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

[0029] It should be noted that the terms "a" and "a plurality of" used in this application are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0030] The following detailed description of the ultrasonic-based triaxial stress field imaging method for metals provided in this application, in conjunction with the accompanying drawings and specific embodiments, is provided in detail.

[0031] like Figure 1 As shown, the metal triaxial stress field imaging method based on ultrasonic measurement provided in this application mainly includes steps S101-S105.

[0032] S101. The simulated direction of triaxial stress in metal is obtained through simulation.

[0033] Among them, the metals mentioned above may include high-temperature alloys, which are a class of metallic materials that can work for a long time under high temperature above 600°C and under certain stress without significant performance degradation.

[0034] Triaxial stress in metals refers to the stresses simultaneously acting in three mutually perpendicular directions within a metallic material. Triaxial stress can be caused by external loads during manufacturing or use, or it can exist as an internal self-balancing stress state without significant external loads. The ultrasonic-based triaxial stress field imaging of metals provided in this application can reconstruct and image the actual triaxial stress field caused by external loads, as well as the triaxial residual stress field without external loads. This application uses the reconstruction and imaging of the triaxial residual stress field as an example for illustration.

[0035] Triaxial residual stress in metals exists in three mutually perpendicular directions and can form during material manufacturing, processing, heat treatment, and service. The presence of triaxial residual stress has a significant impact on the performance of metal parts, potentially affecting dimensional stability, fatigue life, corrosion resistance, and overall strength. Therefore, during the design and manufacture of metal parts, various methods are used to measure and analyze triaxial residual stress in order to take appropriate measures to mitigate its adverse effects.

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

[0037] In one possible implementation, the simulation direction of the triaxial stress of the metal is obtained through simulation, including: establishing a thermodynamic simulation model of the metal based on pre-set 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] The heat treatment process of metals is simulated using thermodynamic finite element analysis to obtain the simulated directions of triaxial stress in the metal. The aforementioned thermodynamic finite element algorithm can be implemented using finite element simulation software; however, the type of finite element simulation software is not limited in this embodiment.

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

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

[0041] Furthermore, during the simulation, the geometric model of the metal can be any shape, such as a cylinder or cuboid; this embodiment is not specifically limited. The temperature-dependent thermodynamic parameters involved in the thermal conductivity analysis, such as the coefficient of thermal expansion, thermal conductivity, specific heat capacity, density, Young's modulus, hardening coefficient, and yield strength, are determined based on the metal material used in the experiment.

[0042] In one example, the simulation of water quenching after solution treatment of a high-temperature alloy involves removing the bar from a solution treatment furnace at T degrees Celsius and then water quenching it. During the finite element simulation analysis, a thermal analysis of the high-temperature alloy is performed first, followed by a force analysis based on the results. Using the aforementioned thermodynamic finite element algorithm, the simulated directions of the triaxial stresses in the high-temperature alloy can be obtained.

[0043] S102. Establish the stress reconstruction coefficient matrix based on the acoustoelastic theoretical model of the influence of triaxial stress on ultrasonic velocity.

[0044] Existing research on triaxial stress detection often only considers the case where the propagation direction of ultrasound is parallel to the stress, i.e., the influence of uniaxial stress parallel to the propagation direction on the longitudinal wave or critically refracted longitudinal wave, and provides corresponding analytical calculation expressions. In this application, an analytical expression for the effect of triaxial stress on the propagation speed of ultrasound is given, which can characterize the influence of arbitrary triaxial stress on the propagation speed of ultrasound.

[0045] The acoustoelastic model of the effect of triaxial stress on ultrasonic velocity is a physical model describing the relationship between the elastic properties of a material and the sound wave propagation characteristics under stress. The stress reconstruction coefficient matrix is ​​a systematic matrix of the changes in ultrasonic propagation time under the influence of triaxial stress.

[0046] In one possible implementation, such as Figure 2 As shown, the process of establishing the stress reconstruction coefficient matrix based on the acoustoelastic theoretical model of the influence of triaxial stress on ultrasonic velocity mainly includes S201-S204.

[0047] S201. The acoustoelastic theoretical model of the influence of triaxial stress on ultrasonic velocity is derived to obtain the calculation formula of the stress influence coefficient. The calculation formula of the stress influence coefficient is used to reflect the influence of the triaxial stress change on the wave propagation time change.

[0048] The acoustic elastic theoretical model of the effect of triaxial stress on ultrasonic velocity, expressed in terms of initial coordinates, is solved and derived using the simulation direction of triaxial stress in metal. The relationship between the change in wave propagation velocity and the change in triaxial stress is obtained. The relationship between the change in wave propagation velocity and the change in triaxial stress is derived and transformed to obtain the relationship between the change in wave propagation time and the change in triaxial stress. The relationship between the change in wave propagation time and the change in triaxial stress is shown in formula (1):

[0049]

[0050] in,

[0051] Where Δt represents the change in wave propagation time, and dσ represents the change in triaxial stress. The formula for calculating the stress influence coefficient, L i Let ρ0 be the wave propagation distance, V0 be the metal density without stress, V0 be the longitudinal wave propagation velocity without stress, K and S be determined by the material's second modulus λ and μ, the material's third modulus l, m, and n, and the triaxial stress direction be determined by the wave propagation direction.

[0052] Specifically, the acoustic elastic theoretical model of the effect of triaxial stress on ultrasonic velocity, expressed in terms of initial coordinates, is solved and derived using the simulation direction of triaxial stress in metal, and the relationship between the change in ultrasonic propagation velocity and the change in triaxial stress is obtained.

[0053] The propagation speed of ultrasound in materials with internal stress depends not only on the material's density and Lamé constant, but also on higher-order elastic constants and the initial stress state. This relationship between the propagation speed of ultrasound and the stress state is called the acoustoelastic effect. To describe the different states of an object, three states are usually defined: the natural state, the initial state, and the final state. The acoustoelastic theory describes these three states as follows: Figure 3 As shown, the natural state refers to the undeformed state of an object without stress or 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 when a small acoustic perturbation is superimposed on a deformed object, and its position vector is represented by x. All physical variables and material properties in the three states are represented by superscripts o, i, and f, respectively. The deformation from the natural state to the initial state is u. i =X-ξ, the transformation from the natural state to the final state is u f =x-ξ, and the transformation from the initial state to the final state is u=xX.

[0054] The acoustoelastic theoretical model of the effect of triaxial stress on ultrasonic velocity, expressed in terms of initial coordinates, is shown in Equation (2).

[0055]

[0056] In the formula, c IJKL c represents the equivalent stiffness in terms of the initial coordinates. IJKL Let c be the Lamé constant of the material. IJKLMN The third elastic constant of the material, Let X be the displacement in the initial state. M For the initial state position vector components, These are the initial state strain tensor components. Let ρ be the Cauchy stress tensor in the initial state. i Let be the initial density. The material under study is represented by the Murnaghan model, and its Lamé constant c is... IJKL The third elastic constant c is completely expressed by the Lamé constants λ and μ. IJKLMN It can be completely represented by l, m, and n.

[0057] Based on the derived acoustoelastic equation with initial coordinates, a program is written. The material density ρ, λ, μ, l, m, n, the triaxial stress direction in the spatial coordinate system, and the ultrasonic wave propagation direction in the spatial coordinate system are input. The program can calculate the wave propagation velocity of the ultrasonic wave in the set wave propagation direction under the triaxial stress tensor.

[0058] A further acoustic elastic theoretical model of the influence of triaxial stress variation on wave propagation time variation and ultrasonic velocity is established. The derivation is based on a spatial coordinate system, using triaxial stress in the form of a stress tensor. Since the triaxial stress tensor contains many unknowns, the stress tensor at each point is transformed into the stress state of each infinitesimal element represented by principal stresses through coordinate transformation, and then represented by a triaxial stress vector in the local coordinate system.

[0059] Ultrasonic waves propagate inside metal. Assume the direction of ultrasonic wave propagation in a spatial coordinate system is... The coordinate system setup and simulation direction for triaxial stress are explained as follows: Figure 4 As shown, the triaxial stress vector in the local coordinate system x1y1z1 is expressed as follows: Where σ is the magnitude of the triaxial stress vector, a is the projection coefficient of the triaxial stress vector on the x1 axis, b is the projection coefficient of the triaxial stress vector on the y1 axis, and c is the projection coefficient of the triaxial stress vector on the z1 axis.

[0060] The direction of ultrasonic wave propagation Representation of the triaxial stress vector in the local coordinate system By solving the acoustoelastic theoretical model (Equation 2) of the effect of triaxial stress on ultrasonic velocity expressed in the initial coordinates and further taking the partial derivative, the relationship between the change in ultrasonic wave propagation velocity and the change in triaxial stress can be obtained as Equation (3).

[0061]

[0062] In formula (3),

[0063] Where σ is the triaxial stress vector, dσ is the triaxial stress variation, a, b, and c are the projection coefficients of the triaxial stress, and L i Let ρ be the propagation distance of the ultrasonic wave, ρ be the material density of the metal under stress-free conditions, V0 be the propagation distance of the longitudinal wave under stress-free conditions, λ and μ be Lamé constants, and l, m, and n be 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 x1y1z1.

[0064] The required density ρ0 and the ultrasonic wave propagation velocity V0 under stress-free conditions in the above formulas were determined experimentally using a calibration component without internal stress. The Lamé constants λ and μ can be fully determined by mechanical tensile tests. l, m, and n are determined experimentally based on formulas derived from the fundamental acoustoelastic equation. Experiments were conducted using Lcr waves propagating in the parallel stress direction, transverse waves propagating perpendicular to the stress direction and in the direction of particle vibration parallel to the stress direction, and longitudinal waves propagating perpendicular to the stress direction. These experiments yielded three sets of relationships between the changes in sound velocity and the changes in uniaxial stress, which were then solved using the acoustoelastic theory equations to derive l, m, and n. The projection coefficients a, b, and c in the triaxial stress vector were determined by the simulated directions in the triaxial stress vector in S101.

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

[0066] Specifically, assuming that ultrasound travels a distance L... i If the time taken for internal propagation is t, then its propagation speed over that propagation distance is as shown in formula (4).

[0067]

[0068] Among them, L i V is the wave propagation distance, t is the wave propagation time for that distance, and V is the wave propagation time. L The wave propagation speed is the distance the wave travels in that segment.

[0069] Differentiating the wave propagation speed of ultrasound with respect to the wave propagation time t in formula (4) yields formula (5).

[0070]

[0071] Substituting formula (5) into formula (3), and approximating t = t0 (the change in wave propagation time caused by stress is small), we can obtain the wave propagation distance L at a certain distance. i The change in wave propagation time caused by triaxial stress is given by formula (6).

[0072]

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

[0074]

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

[0076] in, The formula for calculating the stress influence coefficient.

[0077] S202. Discretize the metal region into N grid regions. Where N is greater than or equal to 2.

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

[0079] The contour plot of the triaxial stress field of a metal can be described by a two-dimensional function, where x and y are the coordinates of a spatial pixel, and the function value corresponds to the value of the contour plot image, i.e., the brightness of the image. The function value corresponds to the amplitude of the triaxial stress in the known simulation direction.

[0080] In this embodiment, taking a square region as an example, the region to be reconstructed is discretized into N = n × n square grid regions, each grid region being a pixel. The density of the discrete pixels determines the accuracy of the image. The triaxial stress field characterization image of the tested metal is included within the reconstruction region. The region to be reconstructed can be understood as a custom region.

[0081] The general discretization of the region to be reconstructed and the projected region are as follows: Figure 5 As shown, the area to be reconstructed is discretized into 400 = 20 × 20 grid regions. The grid regions are numbered sequentially from left to right and from bottom to top to form the required imaging area.

[0082] S203. Based on the calculation formula of stress influence coefficient, calculate the stress influence coefficient of M sound beam paths in each grid region.

[0083] Sound beam transmission through metal refers to the process of ultrasonic waves propagating through metallic materials. This process involves ultrasonic waves entering the metal material from the excitation location, passing through the metal, and then being captured by a probe at the receiving location.

[0084] The excitation and receiving positions of the ultrasonic waves are preset, and then M sound beam paths are determined. The wave propagation distance in each grid area when each sound beam path penetrates the metal is calculated.

[0085] The wave propagation distance in each grid region refers to the distance the excitation signal travels through the metallic material within each grid region, such as... Figure 5 The distance traveled by the sound beam path i in the grid region j as it penetrates the metallic material is shown.

[0086] In one possible implementation, the stress influence coefficient of the M sound beam paths in each grid region is calculated based on the formula for calculating the influence coefficient. This includes: pre-setting multiple excitation positions and multiple receiving positions, and determining the M sound beam paths based on the multiple excitation positions and multiple receiving positions, wherein the multiple excitation positions are set in different directions of the region to be reconstructed, and the multiple receiving positions are set in different directions of the region to be reconstructed; for each of the M sound beam paths, the wave propagation distance of the sound beam path in each grid region is calculated; and the stress influence coefficient of the sound beam path in each grid region is calculated based on the formula for calculating the stress influence coefficient, the material properties of the high-temperature alloy, and the wave propagation distance in each grid region.

[0087] In this embodiment, with the midpoint of the region to be reconstructed as the midpoint, multiple excitation positions are distributed on a ring centered at the midpoint. This ring is on the same plane as the region to be reconstructed, and the multiple excitation positions are spaced equidistantly. In other words, the multiple excitation positions are distributed at periodically different locations within the region to be reconstructed. Similarly, multiple receiving positions are distributed on a ring centered at the midpoint. This ring is on the same plane as the region to be reconstructed, and the multiple receiving positions are spaced equidistantly. In other words, the multiple receiving positions are distributed at periodically different locations within the region to be reconstructed.

[0088] Since the sound beams are emitted from the excitation location and received by the receiving location, the M sound beam paths can be distributed at each location in the region to be reconstructed.

[0089] As described in the above embodiments, after the excitation and receiving positions are determined, a straight line is drawn based on the two points, and the expression for the sound beam path is calculated. This expression is then 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 fixed, the intersection points of the sound beam path with the boundaries of each grid region are calculated. For a given grid region, the distance between the intersection points of the two boundary borders is taken as the wave propagation distance of the sound beam path within that grid region.

[0090] Specifically, based on the excitation and reception positions of the ultrasonic waves, their coordinates are converted into the coordinates of the area to be reconstructed.

[0091] The wave propagation distances of the M sound beam paths in each grid region are calculated, which are the wave propagation distances L in the formula for calculating 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 a coefficient representing the influence of triaxial stress on the change in wave propagation time within each grid region. This is the stress influence coefficient of the grid region.

[0092] The calculation methods and meanings of K, S, V0, and ρ0 can be referred to the descriptions in the above embodiments, and will not be specifically elaborated in the embodiments of this application.

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

[0094] Let w be the coefficient of the wave propagation time variation caused by the triaxial residual stress in the j-th region grid for the i-th sound beam path. ij Let M be the total number of sound beam paths, then the stress reconstruction coefficient matrix is ​​given by w ij The resulting M×N dimensional matrix.

[0095] Thus, the M×N dimensional stress reconstruction coefficient matrix is ​​obtained.

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

[0097] Sound beam path transmission through metal refers to the process of ultrasonic waves propagating in high-temperature alloy materials. This process involves the ultrasonic waves entering the high-temperature alloy from the excitation position, undergoing a series of reflections, refractions, and attenuations within the alloy, before being captured by a probe at the receiving position.

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

[0099] For each sound beam path, there exists a corresponding change in wave propagation time. With M sound beam paths, M changes in wave propagation time can be obtained. In this embodiment, the change in wave propagation time difference formed by a single sound beam path is used as an example for illustration.

[0100] In one possible implementation, the wave propagation time variation of M sound beams passing through the metal is collected, including: for each of the M sound beam paths, obtaining the wave propagation time of the sound beam path passing through the metal under no stress influence; obtaining the wave propagation time of the sound beam path passing through the metal under triaxial stress influence; and subtracting the wave propagation time under triaxial stress influence from the wave propagation time under no stress influence to obtain the wave propagation time variation of the sound beam path under triaxial stress influence.

[0101] Stress-free operation can be understood as the absence of additional mechanical or residual stress in the metal during ultrasonic testing. This typically occurs under ideal conditions where the high-temperature alloy 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 high-temperature alloy. The ultrasonic wave can be a short-duration, high-frequency vibration, the frequency, amplitude, and shape of which can be selected according to specific testing requirements.

[0102] Wave propagation time can be obtained using any of the following methods: cross-correlation analysis, Hilbert transform, zero-intercept method, etc. Cross-correlation analysis determines the time delay between the excitation and received signals by calculating their similarity. The zero-intercept method determines the time delay by detecting the moment the received signal crosses a zero level. The Hilbert transform method performs a Hilbert transform on the received signal to obtain an analytic signal, and then determines the time delay based on the envelope of the analytic signal.

[0103] This application describes the process of calculating wave propagation time using cross-correlation analysis in the embodiments.

[0104] A method for calculating the propagation time of a wave without stress includes: acquiring a first received signal and an excitation signal of the sound beam path under stress-free conditions; performing a cross-correlation analysis on the excitation signal and the first received signal to obtain the propagation time of the ultrasonic wave under stress-free conditions.

[0105] The first received signal refers to the transmitted signal received by the probe without stress. The high-temperature alloy is set to a stress-free state, and an appropriate frequency and pulse width are selected according to the required detection depth and resolution. A suitable voltage is applied to generate the desired excitation signal. The excitation signal is transmitted through the high-temperature alloy; the first received signal is the distinct signal received by the probe at the receiving position.

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

[0107] Acquire the waveforms of the excitation signal and the first received signal, including their frequency, amplitude, and shape. 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] The excitation signal and the first received signal are converted into digital signals. A software tool is used to perform a cross-correlation operation on the excitation signal and the received signal to find the maximum value point of the cross-correlation function. The time offset corresponding to this point is the wave propagation time of the excitation signal and the first received signal.

[0109] A method for calculating the wave propagation time under the influence of triaxial stress includes: acquiring the second received signal and the excitation signal of the sound beam path under the influence of triaxial residual stress, 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 high-temperature alloy is set to a state of triaxial residual stress, and an excitation signal of the same waveform is transmitted through the high-temperature alloy. The obvious signal received by the probe at the receiving position is the second received signal.

[0111] The method for calculating the wave propagation time between the excitation signal and the second received signal is the same as the method for calculating the wave propagation time between the excitation signal and the first received signal. For details, please refer to the description in the above embodiments. This application will not repeat the description in the embodiments.

[0112] The wave propagation time of the excitation signal and the second received signal under the influence of triaxial stress is calculated by subtracting the wave propagation time of the excitation signal and the first received signal under the influence of no stress. The difference between the two is the change in wave propagation time of a single sound beam path under the influence of triaxial residual stress.

[0113] For each of the M sound beam paths, the wave propagation time variation calculation method described above is used to calculate the corresponding wave propagation time variation, resulting in M ​​wave propagation time variations. Here, the wave propagation time variation is represented by p, where p... i This represents the change in wave propagation time corresponding to the i-th sound beam path, where i is greater than or equal to 1 and less than or equal to M.

[0114] S104. Based on the stress reconstruction coefficient matrix and the change in wave propagation time, the amplitude of the triaxial stress is obtained by reconstruction.

[0115] After discretizing the triaxial stress contour map, the reconstruction problem essentially involves solving the equation p = Ax. Here, A is the stress reconstruction coefficient matrix, determined by the propagation distance of each hypothetical sound beam path through each grid region; x is the amplitude matrix of the triaxial residual stress. i is the amplitude of the triaxial stress to be reconstructed in each grid region, and p is the matrix of changes in the propagation time of M waves.

[0116] An iterative reconstruction algorithm is used to solve for the amplitude matrix x of the triaxial residual stress. Based on the iterative reconstruction algorithm, a basic algorithm can be developed, the core idea of ​​which is to ensure that the estimated image satisfies the iterative equation in each image update. In each iteration, the algebraic reconstruction algorithm only uses the change in wave propagation time of a single sound beam path to update the triaxial stress amplitude corresponding to the grid region traversed by that ray. The iterative reconstruction process of the triaxial stress amplitude is as follows: Figure 6 As shown.

[0117] The following section introduces the process of solving the magnitude matrix x of the triaxial residual stress.

[0118] S301. Obtain the initial values ​​of the triaxial stress amplitude within j grid regions.

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

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

[0121] S304. Correct the triaxial stress amplitude of the j-th grid region to obtain the corrected triaxial stress amplitude.

[0122]

[0123] S305, i equals i plus 1.

[0124] S306. Determine if i is less than or equal to M. If yes, return to step S302. If no, proceed to step S307.

[0125] S307. Calculate the corrected triaxial stress amplitude. The second derivative with respect to the length of the grid boundary.

[0126] S308. Determine whether the second derivative is less than the set threshold. If yes, execute S310; otherwise, execute S309.

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

[0128] S310, Judgment If not, return and execute S301. If yes, execute S311.

[0129] S311, The corrected triaxial stress amplitude As output.

[0130] After solving the problem according to the above steps, the magnitude matrix x of the triaxial stress can be obtained.

[0131] S105. Perform triaxial stress field imaging based on triaxial stress direction and triaxial stress amplitude.

[0132] After obtaining the amplitude matrix of the imaging triaxial stress, multiplying it by the simulation direction of the triaxial stress obtained from the thermodynamic simulation yields the triaxial stress cloud map of the metal, namely the axial, circumferential, and radial triaxial stress cloud map of the metal.

[0133] In this embodiment, a linearized analytical expression is established between the change in wave propagation time of ultrasound and the change in triaxial stress. Based on an iterative reconstruction algorithm, the triaxial residual stress of metal is characterized. A method for inverting and characterizing the triaxial residual stress of metal based on ultrasonic measurement is proposed, enabling the reconstruction of the triaxial residual stress field of metal when the direction of the residual stress is obtained through thermal simulation. When the direction of the triaxial residual stress is known, based on the acoustoelastic theoretical model of the influence of triaxial stress on ultrasonic velocity and the internal definition representation method of the part, the coefficients of the change in wave propagation time and the change in stress at each pixel in the region to be characterized are obtained through coordinate system transformation, constructing the influence coefficient matrix required for stress characterization. Combining the influence coefficient matrix with the wave propagation time changes of multiple metal sound beam paths collected under the influence of triaxial residual stress, an equation to be solved is constructed, forming a residual stress inversion and characterization method based on an iterative reconstruction algorithm.

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

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

[0136] Running the simulation based on the above settings will yield simulation results under stress-free conditions, as shown below. Figure 8 As shown in (a), the simulation results under residual stress state are as follows: Figure 8 As shown in (b), it can be seen that longitudinal waves, transverse waves, and surface waves are excited under both stress-free and residual stress conditions. Ultrasonic waves propagate in the structure as longitudinal waves, transverse waves, head waves, and surface waves propagating along the boundary. Among these, longitudinal waves have the highest wave velocity and arrive at all monitoring points first, followed by head waves, while surface waves have the lowest wave velocity. The ultrasonic wave used to calculate the wave propagation time is the longitudinal wave.

[0137] By extracting the velocity of the ultrasonic wave along the x and y directions, synthesizing the corresponding velocity vector, and projecting it onto the vector direction formed by the excitation point to the monitoring point, the ultrasonic received signal propagating from the excitation point to the monitoring point can be obtained.

[0138] For z points, each point is selected as an excitation point in turn. An excitation signal is emitted at the excitation point and received at other points other than the excitation point. The omnidirectional excitation signal and received signal are obtained, and the change in wave propagation time of ultrasound under stress under multi-directional multi-beam path can be obtained.

[0139] The corresponding results were collected at different locations, and the corresponding changes in wave propagation time were obtained through cross-correlation analysis.

[0140] Based on the aforementioned multi-sensor and multi-receiver results obtained from ultrasonic measurements, the residual stress inside the cylindrical structure was characterized. The original residual stress field distribution of the results to be reconstructed is as follows: Figure 7 As shown. Dividing the required imaging region into a 100×100 grid results in an imaging resolution of 1 mm. The coefficient matrix constructed by the internal stress algebraic reconstruction algorithm has 72×43=3096 rows and 10000 columns. The convergence condition is set as a rate of change of less than 1% for 10 consecutive generations; the residual stress optimization calculation converges in the 18th generation.

[0141] The triaxial stress field results obtained from the inversion are as follows Figure 9 As shown, Figure 9 (a) shows the results of reconstructing the radial residual stress of the bar. Figure 9 (b) shows the reconstruction results of the circumferential residual stress in the bar. Figure 9 (c) shows the reconstruction results of the axial residual stress in the bar. The triaxial stress field can be reconstructed well, and the relative error of the maximum stress value in each of the three dimensions is less than 25%, indicating that the stress amplitude of the specific triaxial stress field can be reconstructed well. The order of magnitude of the triaxial stress value of the metal can be obtained through this method. Considering the characteristics of residual stress distribution, a certain lateral and longitudinal smoothing constraint is imposed on the continuity of the mesh in the inversion method. That is, sudden oscillations or abrupt alternations between positive and negative values ​​are not allowed in each row and column of the mesh. Therefore, some lateral artifacts appear in the results during inversion.

[0142] In actual production, processed parts often undergo further vibration or aging treatments to reduce internal residual stress. Therefore, the effectiveness of residual stress reduction methods can be assessed by examining parts before and after treatment. Simultaneously, multiple ultrasonic beam paths can be measured to characterize the triaxial stress amplitude within the part, serving as a benchmark. Furthermore, when manufacturing new parts, stress inversion characterization is performed by measuring the change in wave propagation time. The characterization results are then compared with the benchmark results to determine whether the newly manufactured parts numerically meet the standards.

[0143] The inversion results show that, according to the proposed bar residual stress characterization method based on iterative reconstruction algorithm, the stress profile distribution can be reconstructed well, except for the stress amplitude range. Further statistical analysis of the stress characterization results and evaluation of the location and regional accuracy of the characterization results demonstrate high effectiveness in the core inversion results.

[0144] Figure 10 This is a schematic diagram of a metal triaxial stress field imaging device based on ultrasonic measurement, as described in an embodiment of this application. Figure 10 As shown, the metal triaxial stress field imaging device 100 based on ultrasonic measurement provided in this application mainly includes: a stress direction acquisition module 101, a coefficient matrix establishment module 102, a wave propagation time change acquisition module 103, a triaxial stress amplitude calculation module 104, and a triaxial stress imaging module 105.

[0145] The system includes: a stress direction acquisition module 101, used to obtain the simulated direction of triaxial stress in the metal through simulation; a coefficient matrix establishment module 102, used to establish a stress reconstruction coefficient matrix based on the acoustoelastic theory model of the influence of triaxial stress on ultrasonic velocity; a wave propagation time change acquisition module 103, used to acquire the wave propagation time change when M sound beams penetrate the metal; a triaxial stress amplitude calculation module 104, used to perform reconstruction and solution based on the stress reconstruction coefficient matrix and the wave propagation time change to obtain the amplitude of triaxial stress; and a triaxial stress imaging module 105, used to perform triaxial stress field imaging based on the simulated direction of the triaxial stress and the amplitude of the triaxial stress.

[0146] In one possible implementation, the stress direction acquisition module 101 is specifically used to establish a thermodynamic simulation model of the metal 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 triaxial stress of the metal.

[0147] In one possible implementation, the coefficient matrix establishment module 102 is specifically used to derive the acoustoelastic theoretical model of the influence of triaxial stress on ultrasonic velocity, and obtain the calculation formula of the stress influence coefficient. The calculation formula of the stress influence coefficient is used to reflect the influence of the triaxial stress change on the wave propagation time change. The region to be reconstructed is discretized into N grid regions. Based on the calculation formula of the stress influence coefficient, the stress influence coefficients of M sound beam paths in each grid region are calculated. The stress influence coefficients of the M sound beam paths in each grid region are integrated to obtain an M×N dimensional stress reconstruction coefficient matrix.

[0148] In one possible implementation, the coefficient matrix establishment module 102 is specifically used to solve and derive the acoustoelastic theoretical model of the effect of triaxial stress on ultrasonic velocity using the simulation direction of triaxial stress in the metal, to obtain the relationship between the change in wave propagation velocity and the change in triaxial stress; the relationship between the change in wave propagation velocity and the change in triaxial stress is then transformed to obtain the relationship between the change in wave propagation time and the change in triaxial stress; wherein, the relationship between the change in wave propagation time and the change in triaxial stress is as follows:

[0149]

[0150] Where Δt represents the change in wave propagation time, and dσ represents the change in triaxial stress. The formula for calculating the stress influence coefficient, L i Let ρ0 be the wave propagation distance, ρ0 be the metal density under no stress, V0 be the wave propagation velocity, K and S be determined by the material's second modulus λ and μ, the material's third modulus l, m and n, and the triaxial stress direction be determined by the wave propagation direction.

[0151] In one possible implementation, the coefficient matrix establishment module 102 is specifically used to pre-set multiple excitation positions and multiple receiving positions, and determine M sound beam paths based on the multiple excitation positions and multiple receiving positions; wherein the multiple excitation positions are set in different directions of the region to be reconstructed, and the multiple receiving positions are set in different directions of the region to be reconstructed; for each of the M sound beam paths, the wave propagation distance of the sound beam path in each grid region is calculated; based on the calculation formula of the stress influence coefficient, the material properties of the high-temperature alloy, and the wave propagation distance in each grid region, the stress influence coefficient of the sound beam path in each grid region is calculated.

[0152] In one possible implementation, the wave propagation time change acquisition module 103 is specifically used to acquire, for each of the M sound beam paths, the wave propagation time when the sound beam path transmits through the metal under no stress influence; acquire the wave propagation time when the sound beam path transmits through the metal under the influence of triaxial stress; and subtract the wave propagation time under the influence of triaxial stress from the wave propagation time under no stress influence to obtain the wave propagation time change corresponding to the sound beam path under the influence of triaxial stress.

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

[0154] p = Ax;

[0155] Where p is an M×1 matrix representing the change in wave propagation time, A is an M×N matrix representing the stress reconstruction coefficients, and x is an N×1 matrix representing the triaxial stress amplitude.

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

[0157] Figure 11 This is a schematic diagram of the structure of an electronic device provided in this embodiment. The electronic device may include a metal triaxial stress field imaging device based on ultrasonic measurement, such as... Figure 11 As 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 can be one or more. Figure 11 Taking a processor 1110 as an example; the processor 1110, memory 1120, input device 1130 and output device 1140 in the electronic device can be connected by a bus or other means. Figure 11 Taking the example of a connection between China and Israel via a bus.

[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 triaxial residual stress imaging method in this embodiment of the 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, thereby realizing the metal triaxial stress field imaging method based on ultrasonic measurement provided in this embodiment of the invention.

[0159] The memory 1120 may primarily include a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a given function; the data storage area may store data created based on terminal usage. Furthermore, the memory 1120 may include high-speed random access memory and non-volatile memory, such as at least one disk storage device, flash memory, or other non-volatile solid-state storage device. In some instances, the memory 1120 may further include memory remotely located relative to the processor 1110, which can be connected to the electronic device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

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

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

[0162] Of course, the computer-executable instructions provided in the embodiments of the present invention are not limited to the method operations described above, but can also perform related operations in the metal triaxial stress field imaging method based on ultrasonic measurement provided in any embodiment of the present invention.

[0163] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, 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 computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0164] It is worth noting that in the embodiments of the above-mentioned 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 each functional unit are only for easy differentiation and are not used to limit the scope of protection of the present invention.

[0165] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0166] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for imaging the triaxial stress field of metals based on ultrasonic measurement, characterized in that, The method includes: The simulated direction of triaxial stress in the metal is obtained through simulation; A stress reconstruction coefficient matrix is ​​established based on the acoustoelastic theoretical model of the influence of triaxial stress on ultrasonic velocity. Collect the change in wave propagation time when M sound beams pass through the metal; The amplitude of the triaxial stress is obtained by reconstructing and solving based on the stress reconstruction coefficient matrix and the wave propagation time change. Triaxial stress field imaging is performed based on the simulated direction and amplitude of the triaxial stress. The acoustoelastic theoretical model based on the influence of triaxial stress on ultrasonic velocity establishes a stress reconstruction coefficient matrix, including: The acoustoelastic theoretical model of the effect of triaxial stress on ultrasonic velocity is derived to obtain the calculation formula of the stress influence coefficient. The calculation formula of the stress influence coefficient is used to reflect the influence of the triaxial stress change on the wave propagation time change. Discretize the region to be reconstructed into N grid regions; Based on the formula for calculating the stress influence coefficient, the stress influence coefficient of the M sound beam paths in each grid region is calculated. The stress influence coefficients of the M sound beam paths in each grid region are integrated to obtain an M×N dimensional stress reconstruction coefficient matrix; Through coordinate system transformation, the acoustoelastic theoretical model of the influence of triaxial stress on ultrasonic velocity is derived, resulting in the calculation formula for the stress influence coefficient, including: The acoustic elastic theoretical model of the effect of triaxial stress on ultrasonic velocity was solved and derived using the simulation direction of the triaxial stress of the metal, and the relationship between the change in wave propagation velocity and the change in triaxial stress was obtained. The relationship between the change in wave propagation velocity and the change in triaxial stress is derived and transformed to obtain the relationship between the change in wave propagation time and the change in triaxial stress. The relationship between the change in wave propagation time and the change in triaxial stress is expressed by the following formula: ； in, , This represents the change in wave propagation time. This represents the amount of triaxial stress change. The formula for calculating the stress influence coefficient. For the distance the wave propagates, The density of a high-temperature alloy under stress-free conditions. The longitudinal wave propagation velocity under stress-free conditions. and From the second modulus of the material , and the third modulus of the material , , Sure.

2. The method according to claim 1, characterized in that, The simulation direction of the triaxial stress in the metal obtained through simulation includes: A thermodynamic simulation model of a metal is established based on pre-defined 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 simulated direction of the triaxial stress of the metal.

3. The method according to claim 1, 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 region is calculated, including: Multiple excitation positions and multiple receiving positions are preset, and M sound beam paths are determined based on the multiple excitation positions and multiple receiving positions, wherein the multiple excitation positions are set in different directions of the region to be reconstructed, and the multiple receiving positions are set in different directions of the region to be reconstructed; For each of the M sound beam paths, calculate the wave propagation distance of the sound beam in each grid region; Based on the calculation formula of the stress influence coefficient, the material properties, and the wave propagation distance in each grid region, the stress influence coefficient of the sound beam path in each grid region is calculated.

4. The method according to claim 1, characterized in that, The measurement of wave propagation time changes when M ultrasonic beams pass through the metal includes: For each of the M sound beam paths, obtain the wave propagation time when the sound beam passes through the metal under stress-free conditions; The propagation time of the sound beam when it passes through the metal under the influence of the triaxial stress is obtained; The difference between the wave propagation time under the influence of triaxial stress and the wave propagation time without stress is used to obtain the change in wave propagation time of the sound beam under the influence of triaxial stress.

5. The method according to claim 1, characterized in that, The reconstruction solution based on the stress reconstruction coefficient matrix and the wave propagation time change yields the amplitude of the triaxial stress, including: The following equation is solved using an iterative reconstruction algorithm to obtain the amplitude of the triaxial stress. ； in, Let M×1 be the wave propagation time variation matrix. The stress reconstruction coefficient matrix is ​​of size M×N. It is an N×1 dimensional triaxial stress amplitude matrix.

6. A metal triaxial stress field imaging device based on ultrasonic measurement, characterized in that, The device includes: The stress direction acquisition module is used to obtain the simulated direction of triaxial stress in metals through simulation. The coefficient matrix establishment module is used to establish the stress reconstruction coefficient matrix based on the acoustoelastic theoretical model of the influence of triaxial stress on ultrasonic velocity. The wave propagation time change acquisition module is used to acquire the wave propagation time change when M sound beams pass through the metal. The triaxial stress amplitude calculation module is used to reconstruct and solve the triaxial stress based on the stress reconstruction coefficient matrix and the wave propagation time change, so as to obtain the amplitude of the triaxial stress. The triaxial stress imaging module is used to perform triaxial stress field imaging based on the simulated direction and amplitude of the triaxial stress. The acoustoelastic theoretical model based on the influence of triaxial stress on ultrasonic velocity establishes a stress reconstruction coefficient matrix, including: The acoustoelastic theoretical model of the effect of triaxial stress on ultrasonic velocity is derived to obtain the calculation formula of the stress influence coefficient. The calculation formula of the stress influence coefficient is used to reflect the influence of the triaxial stress change on the wave propagation time change. Discretize the region to be reconstructed into N grid regions; Based on the formula for calculating the stress influence coefficient, the stress influence coefficient of the M sound beam paths in each grid region is calculated. The stress influence coefficients of the M sound beam paths in each grid region are integrated to obtain an M×N dimensional stress reconstruction coefficient matrix; Through coordinate system transformation, the acoustoelastic theoretical model of the influence of triaxial stress on ultrasonic velocity is derived, resulting in the calculation formula for the stress influence coefficient, including: The acoustic elastic theoretical model of the effect of triaxial stress on ultrasonic velocity was solved and derived using the simulation direction of the triaxial stress of the metal, and the relationship between the change in wave propagation velocity and the change in triaxial stress was obtained. The relationship between the change in wave propagation velocity and the change in triaxial stress is derived and transformed to obtain the relationship between the change in wave propagation time and the change in triaxial stress. The relationship between the change in wave propagation time and the change in triaxial stress is expressed by the following formula: ； in, , This represents the change in wave propagation time. This represents the amount of triaxial stress change. The formula for calculating the stress influence coefficient. For the distance the wave propagates, The density of a high-temperature alloy under stress-free conditions. The longitudinal wave propagation velocity under stress-free conditions. and From the second modulus of the material , and the third modulus of the material , , Sure.

7. An electronic device, characterized in that, The device includes: One or more processors; 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 1-5.

8. A storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the metal triaxial stress field imaging method based on ultrasonic measurement as described in any one of claims 1-5.

Images