A method, system, medium and device for visual inversion of stress field in coal and rock mass

Abstract

The present invention discloses a method, system, medium and device for visual inversion of the stress field of coal and rock masses, which relates to the field of stress calculation of engineering materials in mining engineering and geotechnical engineering. The method includes: collecting the energy values of acoustic emission electrical signals during the fracture process of different parts of the target object to be measured; calculating the equivalent stress corresponding to each part according to the acoustic emission electrical signals of each part and in combination with a preset proportional coefficient; obtaining the stress field distribution result of the target object to be measured by combining the equivalent stresses of all parts within the target object to be measured and processing with an interpolation algorithm; and performing visual display on the stress field distribution result, and obtaining the magnitude and distribution law of the stress field of the test piece and the calculation of the stress field through the acquisition and processing means of acoustic emission signals, realizing full stress field measurement, and not only being able to obtain the difference between the principal stresses, but also being able to obtain the individual stresses.

Description

Technical Field

[0001] The present invention relates to the field of stress calculation of engineering materials in mining engineering and geotechnical engineering, and particularly to a method, system, medium and device for visual inversion of the stress field of coal and rock masses. Background Technique

[0002] Rock is the main object of coal resource development and engineering construction. The mining of coal and engineering construction break the balance state of the initial stress field of coal and rock masses, causing the redistribution of the coal and rock stress field, and then inducing major disasters such as rock bursts, gas outbursts, and mine tremors. Therefore, the inversion calculation and visualization of the stress field have important value for the safety assessment of mining engineering and the early warning of disasters. When stress concentration occurs in a local area of a material, energy will be quickly released and transient elastic waves will be generated. This phenomenon is called the acoustic emission phenomenon. The present invention mainly obtains the magnitude and distribution law of the stress field of the test piece through the acquisition and processing of acoustic emission signals. The calculation of the stress field mainly has the following several methods in China at present:

[0003] By installing stress gauges on the test piece to obtain the stress field, the defect of this method is that it can only calculate the stress on the surface of the test piece, and the stress value inside the test piece cannot be calculated. In addition, this method can only monitor some monitoring points and cannot achieve full stress field measurement. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method, system, medium and device for visual inversion of the stress field of coal and rock masses in view of the deficiencies of the prior art.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] A method for visual inversion of the stress field of coal and rock masses includes:

[0007] Collecting the energy values of acoustic emission electrical signals during the fracture process of different parts of the target object to be measured;

[0008] Calculating the equivalent stress value corresponding to each part according to the acoustic emission electrical signal energy of each part and combining a preset proportional coefficient;

[0009] Obtaining the stress field distribution result of the target object to be measured by combining interpolation algorithm processing according to the equivalent stress values of all parts of the target object to be measured;

[0010] Performing visual display on the stress field distribution result.

[0011] The beneficial effects of the present invention are as follows: According to the acoustic emission electrical signal energy of each part and in combination with a preset proportionality coefficient, the equivalent stress value corresponding to each part is calculated. Based on the equivalent stress values of all parts of the target object to be measured and through interpolation algorithm processing, the stress field distribution result of the target object to be measured is obtained. Through the acquisition and processing of acoustic emission signals, the magnitude and distribution law of the stress field of the test piece are obtained, and the stress field is calculated, realizing full stress field measurement. Not only can the equivalent stress value be obtained, but also the individual stress can be obtained.

[0012] It can not only calculate the stress field on the surface of the test piece but also calculate the internal stress distribution.

[0013] Further, the acoustic emission electrical signal energy of the test piece is collected by an acoustic emission device; wherein, the test piece and the target object to be measured are of the same type of test piece;

[0014] Calculate the elastic stress energy of the test piece;

[0015] According to the acoustic emission signal energy and the elastic stress energy, a preset proportionality coefficient is calculated.

[0016] The beneficial effect of adopting the above further solution is that this solution realizes the conversion between acoustic emission energy and mechanical energy through a preset proportionality coefficient.

[0017] Further, it further includes:

[0018] The position of the acoustic emission source is calculated through the arrival time parameter and the signal over-threshold time parameter in the acoustic emission electrical signal, and then the part where the acoustic emission electrical signal energy value is emitted is obtained.

[0019] Further, the interpolation algorithm includes: plane interpolation method and Lagrange interpolation method.

[0020] Another technical solution for the present invention to solve the above technical problems is as follows:

[0021] A visual inversion system for the stress field of coal and rock mass includes: an electrical energy acquisition module, a stress calculation module, a stress distribution acquisition module, and a visual display module;

[0022] The electrical energy acquisition module is used to acquire the acoustic emission electrical signal energy values of different parts of the target object to be measured during the fracture process;

[0023] The stress calculation module is used to calculate the equivalent stress value corresponding to each part according to the acoustic emission electrical signal energy of each part and in combination with a preset proportionality coefficient;

[0024] The stress distribution acquisition module is used to obtain the stress field distribution result of the target object to be measured according to the equivalent stress values of all parts of the target object to be measured and through interpolation algorithm processing;

[0025] The visualization display module is used to visually display the stress field distribution result.

[0026] The beneficial effects of the present invention are as follows: According to the acoustic emission electrical signal energy of each part, combined with a preset proportionality coefficient, the equivalent stress value corresponding to each part is calculated. According to the elastic stress energy of all parts of the target object to be measured, combined with interpolation algorithm processing, the stress field distribution result of the target object to be measured is obtained. Through the acquisition and processing means of acoustic emission signals, the size and distribution law of the stress field of the test piece are obtained, and the calculation of the stress field is realized, so as to achieve full stress field measurement. Not only can the equivalent stress value be obtained, but also the individual stress can be obtained.

[0027] It can not only calculate the stress field on the surface of the test piece, but also calculate the internal stress distribution.

[0028] Furthermore, it further includes: a conversion ratio calculation module, which is used to collect the acoustic emission electrical signal energy of the test piece through an acoustic emission device; wherein, the test piece and the target object to be measured are of the same type of test piece;

[0029] Calculate the elastic stress energy of the test piece;

[0030] Calculate the preset proportionality coefficient according to the acoustic emission signal energy and the elastic stress energy.

[0031] The beneficial effect of adopting the above further solution is: This solution realizes the conversion between acoustic emission energy and mechanical energy through a preset proportionality coefficient.

[0032] Furthermore, it further includes: a positioning module, which is used to calculate the position of the acoustic emission source through the arrival time parameter and the signal over-threshold time parameter in the acoustic emission electrical signal, so as to obtain the part where the acoustic emission electrical signal energy value is emitted.

[0033] Furthermore, the interpolation algorithm includes: a plane interpolation method and a Lagrange interpolation method.

[0034] Another technical solution for the present invention to solve the above technical problems is as follows:

[0035] A storage medium stores instructions, and when a computer reads the instructions, it causes the computer to execute a method for visual inversion of the stress field of a coal rock mass as described in any of the above solutions.

[0036] Another technical solution for the present invention to solve the above technical problems is as follows:

[0037] An electronic device includes a processor and the storage medium described in the above solution, and the processor executes the instructions in the storage medium.

[0038] Advantages of additional aspects of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic flow chart of a method for visual inversion of stress field of coal and rock mass provided for an embodiment of the present invention;

[0040] Figure 2 Block diagram of the structure of a system for visual inversion of stress field of coal and rock mass provided for an embodiment of the present invention;

[0041] Figure 3 Schematic diagram of the arrangement of monitoring sensors for interpolation algorithm provided for other embodiments of the present invention;

[0042] Figure 4 Schematic diagram of three-dimensional positioning of acoustic emission provided for other embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The principles and features of the present invention will be described below with reference to the accompanying drawings. The illustrated embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0044] As Figure 1 shown, a method for visual inversion of stress field of coal and rock mass provided for an embodiment of the present invention includes:

[0045] S1. Collect the energy values of acoustic emission electrical signals at different parts of the target object to be measured during the fracture process. It should be noted that the energy collected by the acoustic emission device is in the format of electrical signals, and the unit of the acoustic emission electrical signal energy is millisecond·millivolt. This energy is different from the energy with the unit of joule used in mining engineering. In the present invention, the elastic strain energy is calculated by combining the crack length with mechanical theory and corresponding to the acoustic emission electrical signal energy, and the proportionality coefficient between the acoustic emission energy and the elastic energy is calculated to achieve the conversion between the acoustic emission energy and the mechanical energy.

[0046] In another embodiment, the conversion between the acoustic emission energy and the mechanical energy specifically includes:

[0047] First, calculate the acoustic emission energy according to the following formula based on the acoustic emission waveform file:

[0048]

[0049] where W AE is the total acoustic emission energy; U is the acoustic emission voltage value t i , t j represents the time when the voltage first and last crosses the threshold voltage.

[0050] This energy is the integral of the absolute voltage value of the acoustic emission signal over time. Since the energy of the acoustic emission electrical signal is extremely small compared to the true energy, artificial amplification is required for calculating the acoustic emission energy. The amplification factor is determined through a three-point bending experiment. The specific method is as follows: Set a three-point bending specimen with a crack length of d0 and a thickness of t. After the experiment, the crack length expands to d. Then the fracture energy G generated during the crack propagation process F is calculated according to the following formula:

[0051]

[0052] Then calculate the ratio k of the two formulas according to the following formula, and k is the amplification factor of the acoustic emission energy:

[0053]

[0054] where, W AE is the total acoustic emission energy; U is the acoustic emission voltage value; W0 is the area enclosed by the stress-strain curve during the crack propagation process.

[0055] S2. According to the acoustic emission electrical signal energy of each part, combined with a preset proportional coefficient, calculate the equivalent stress value corresponding to each part; where the preset proportional coefficient is the amplification factor of the acoustic emission energy.

[0056] In some embodiments, during the rock fracture process, the energies obtained from acoustic emission monitoring are large and small, representing high and low released energies. Based on this phenomenon, it can be known that in the parts with higher acoustic emission energy, the stress is more concentrated and the stress value is larger. In the parts with lower acoustic emission energy, the degree of stress concentration is smaller. Through the equivalent conversion method of acoustic emission electrical signal energy and elastic stress energy, the electrical signal energy is converted into elastic stress energy. According to the magnitude of the acoustic emission energy and mechanical theory, the magnitude of the stress inside the coal and rock mass can be calculated.

[0057] S3. According to the equivalent stress values of all parts of the target to-be-tested, combined with interpolation algorithm processing, obtain the stress field distribution result of the target to-be-tested;

[0058] S4. Visualize the stress field distribution result.

[0059] This solution calculates the equivalent stress value corresponding to each part according to the acoustic emission electrical signal energy of each part, combined with a preset proportional coefficient, and obtains the stress field distribution result of the target to-be-tested according to the equivalent stress values of all parts inside the target to-be-tested, combined with interpolation algorithm processing. Through the acquisition and processing means of acoustic emission signals, the magnitude and distribution law of the stress field of the test piece and the calculation of the stress field are obtained, realizing full stress field measurement. It can not only obtain the equivalent stress value, but also obtain the individual stress.

[0060] It can not only calculate the stress field on the surface of the test piece to be tested, but also calculate the internal stress distribution.

[0061] Optionally, in some embodiments, the acoustic emission electrical signal energy of the test piece is collected by an acoustic emission device; wherein, the test piece and the target to be measured are of the same type of test piece;

[0062] Calculate the elastic stress energy of the test piece;

[0063] Calculate a preset proportionality coefficient according to the acoustic emission signal energy and the elastic stress energy.

[0064] This solution realizes the conversion between acoustic emission energy and mechanical energy through the preset proportionality coefficient.

[0065] Optionally, in some embodiments, it further includes:

[0066] Calculate the position of the acoustic emission source through the arrival time parameter and the signal over-threshold time parameter in the acoustic emission electrical signal, and then obtain the part where the acoustic emission electrical signal energy value is emitted.

[0067] Optionally, in some embodiments, the interpolation algorithm includes: plane interpolation method and Lagrange interpolation method.

[0068] In a certain embodiment, it specifically includes: on the premise of not considering heat exchange, when the coal body is in the process of uniaxial compression failure, the total energy U generated by the external load consists of 2 parts, namely dissipated energy and releasable elastic stress energy:

[0069] W = W d + W e ,

[0070] Wherein, W d represents the dissipated energy, and W e represents the releasable stress energy.

[0071] Under uniaxial compression conditions, the total energy generated by the external load at time t is:

[0072]

[0073] Wherein, ε t , σ t represent the strain and stress of the test piece at time t.

[0074] The releasable elastic stress energy in the specimen at time t is:

[0075]

[0076] Wherein, is the releasable elastic stress energy in the specimen at time t, ε t , σ tRepresents the strain and stress of the specimen at time t, and E is the elastic modulus.

[0077] To obtain the internal stress field, simply obtaining the overall energy does not meet the requirements. Based on the existing acoustic emission location results, it is first assumed that the specimen is composed of n micro-elements of elastoplastic media, and each micro-element is the main load-bearing unit. The acoustic emission events are fused using the energy density index. The specimen is divided into n cubes with a side length R = 1 mm, and the total energy of the acoustic emission events falling into the cubes is statistically calculated. Finally, the energy density of a single micro-element is obtained. When an acoustic emission event occurs at a certain position, it is considered that the micro-element at that point cannot store energy and releases part of it. Based on this principle, the energy value of the area where the acoustic emission event occurs is calculated according to the following formula:

[0078]

[0079] Among them, is the elastic stress energy that can be released in the specimen at time t, W r is the remaining energy at the point to be determined, W AE represents the acoustic emission energy, V is the volume of the specimen, V C is the crack volume, W AE0 is the acoustic emission energy at the point to be determined; V is the volume of the specimen; V c is the crack volume in the specimen.

[0080] Through the above formula derivation, the remaining strain energy of the specimen is calculated, and then according to Green's formula, that is, the rate of change of elastic energy with respect to any stress component,

[0081]

[0082]

[0083]

[0084] That is, the corresponding stress component is obtained.

[0085] In another embodiment, a method for visualizing the stress field of coal and rock mass by acoustic emission location may include:

[0086] The acoustic emission software can locate the position where the acoustic emission event occurs. Based on this means, the acoustic emission electrical signal energy is first converted into elastic stress energy, and then the stress values of each energy point are obtained according to the method of stress inversion of coal and rock mass based on the acoustic emission electrical signal energy. Finally, the full-field stress visualization result of the measured coal and rock mass can be obtained through the interpolation algorithm.

[0087] Among them, in some embodiments, a method for interpolating the three-dimensional stress field of coal and rock may include:

[0088] (1) Monitoring sensor layout

[0089] Divide several k planes in the z direction of the coal rock, and divide the grid into m rows and n columns on each plane, as Figure 3 shown.

[0090] (2) Calculation of one-dimensional stress distribution

[0091] Lagrange interpolation is a polynomial interpolation method. Its implementation principle is to construct a high-order polynomial through multiple sampling points to predict unknown points. Due to its simple structure and convenient representation, it has been widely used in linear interpolation. To construct the Lagrange function, first construct the interpolation basis function as follows:

[0092]

[0093] where l i (x) is the interpolation basis function along the x direction, x i is the x coordinate of the i-th point, i ∈ [1, n], and n is the n-th interpolation point. Based on the following formula, the stress components in the x direction calculated for each row are fitted on the k plane to obtain the row stress interpolation function, and its expression is:

[0094]

[0095] where y j is the y coordinate of any row, j ∈ [1, m], and m is the m-th interpolation point; is the stress value at the x i point in the j-th row of the k plane. Similarly, the strain components calculated in the y direction are fitted on the k plane to obtain the column strain interpolation function as:

[0096]

[0097] According to the calculation results of the row stress interpolation function and the column strain interpolation function, the one-dimensional stress distributions in the x direction and y direction can be obtained respectively.

[0098] (3) Calculation of two-dimensional stress distribution

[0099] Shepard interpolation is a plane interpolation method, also known as the inverse distance weighted method. Its basic principle is to calculate the interpolation point assignment value through the weighted average of the known point coordinates, and define the weight function as inversely proportional to the distance. Based on the Shepard method and the one-dimensional stress interpolation function, the stress interpolation function of any plane can be written as:

[0100]

[0101] where, is the distance from the monitoring point to the interpolation point; ε ijis the stress value at the intersection of the j-th row and the i-th column of an arbitrary plane, u is the weight exponent, and n refers to the n-th interpolation point.

[0102] (4) Calculation of three-dimensional stress distribution

[0103] This patent introduces one-dimensional and two-dimensional interpolation in an arbitrary plane, and uses the Lagrange interpolation method to perform three-dimensional interpolation on multiple interpolation planes. Therefore, three-dimensional interpolation can be converted into a combination of two-dimensional and one-dimensional interpolation. First, the model is divided into k horizontal layers in the vertical direction, and the scatter point values of each interpolation plane in the z direction are determined. Then, Lagrange interpolation is performed along the z direction of the interpolation plane. Based on the above method, the three-dimensional stress function of the studied model is as follows:

[0104]

[0105] where l q (x, y) is the interpolation basis function in the z direction, and q ∈ [1, k]; is the stress value at the k plane.

[0106] Through the above three-dimensional interpolation algorithm, the full-field stress visualization result of the measured coal and rock mass can be obtained.

[0107] In some embodiments, it should be noted that the principle of acoustic emission detection refers to the phenomenon that when a material or structure is subjected to external or internal forces, local stress concentration occurs, resulting in deformation or fracture, and strain energy is released in the form of stress waves. The elastic waves emitted by the acoustic emission source finally propagate to the surface of the material, causing surface displacements that can be detected by acoustic emission sensors. These detectors convert the mechanical vibrations of the material into electrical signals, which are then amplified, processed, and recorded. Changes in internal stress in solid materials generate acoustic emission signals. During the processes of material processing, treatment, and use, many factors can cause changes in internal stress, such as dislocation movement, twinning, crack initiation and propagation, fracture, changes in diffusionless phase transformation, and so on. People analyze and infer based on the observed acoustic emission signals to understand the mechanism of acoustic emission in materials.

[0108] Propagation forms of acoustic emission waves: longitudinal waves, transverse waves, surface waves (Rayleigh waves), plate waves (waves propagating in thin plates with a plate thickness comparable to the wavelength), but generally, acoustic emission only studies longitudinal and transverse waves.

[0109] Waves inevitably attenuate in materials, including: geometric spreading attenuation where, as the acoustic emission wave spreads in all directions from the wave source, the area of the wavefront gradually expands with the increase in propagation distance, causing the energy on the area to gradually decrease and the amplitude of the wave to drop; material absorption attenuation where, when the wave propagates in the medium, due to factors such as internal friction and heat conduction between particles, part of the mechanical energy of the wave is converted into other energies such as heat, causing the amplitude of the wave to decrease exponentially with the propagation distance; scattering attenuation where, when the wave propagates and encounters an interface with uneven acoustic impedance, irregular reflection of the wave occurs, reducing the energy in the original propagation direction of the wave source. The magnitude of propagation attenuation is related to the distance range that each sensor can monitor and becomes a key factor in determining the sensor spacing or operating frequency in source localization. In practical applications, it is usually adopted to reduce the sensor spacing and increase the number of sensors so that more sensors can receive the signal, thereby reducing the impact caused by signal attenuation.

[0110] One very important point in the signal analysis of acoustic emission is positioning. Through the positioning function, the location of the acoustic emission source can be directly known. The principle is that among the acoustic emission characteristic parameters, there is one item which is the arrival time (start time), referring to the moment when the signal crosses the threshold. When the same signal is transmitted to sensors in different channels, although the signal has attenuation and certain deformation, it is assumed here that the attenuation and deformation do not affect the accuracy of the arrival time.

[0111] In one embodiment, as Figure 4 shown, the three-dimensional positioning method may include: defining a three-dimensional coordinate system, assuming the position of sensor 1 is (x1, y1, z1), the position of sensor 2 is (x2, y2, z2), the position of sensor 3 is (x3, y3, z3), the position of sensor 4 is (x4, y4, z4), requiring that the 4 sensors are not on the same plane, and the distances from the signal source to the sensors are s1, s2, s3, s4 respectively. The arrival times of the signal source reaching the sensors are t1, t2, t3, t4 respectively.

[0112] According to the principle that speed * time difference equals distance difference, the following equations are obtained:

[0113]

[0114] s1 - s2 = (t1 - t2) × v,

[0115] s1 - s3 = (t1 - t3) × v,

[0116] s1 - s4 = (t1 - t4) × v,

[0117] Although in practical applications, coal samples are not strictly isotropic homogeneous materials, when the overall differences in materials are not significant, a homogeneous isotropic velocity model is generally still used for approximation. The principle of acoustic emission location is very simple. However, due to factors such as inaccurate arrival times, non-uniform wave velocities, and background noise, the location accuracy is often not high. To solve this problem, we use as many sensors as possible to establish an overdetermined system of equations and then apply the least squares method to solve it to eliminate random errors. Specifically, an overdetermined system of equations refers to a situation where when the number of unknowns to be solved (i.e., the position coordinates x, y, z of the acoustic emission point) is less than the number of given equations, an optimization algorithm needs to be used to calculate the transcendental equation to minimize the calculation result error. In terms of optimization algorithms, in addition to the least squares method mentioned above, there are also optimization algorithms such as genetic algorithms and fish school algorithms. Comparisons will be made through multiple algorithms to select the optimal calculation result.

[0118] In one embodiment, as Figure 2 shown, a visualization inversion system for the stress field of coal and rock masses includes: an electric energy acquisition module 1101, a stress calculation module 1102, a stress distribution acquisition module 1103, and a visualization display module 1104;

[0119] The electric energy acquisition module 1101 is used to acquire the acoustic emission electric signal energy values at different parts of the target to-be-tested object during the rupture process;

[0120] The stress calculation module 1102 is used to calculate the equivalent stress corresponding to each part according to the acoustic emission electric signal energy of each part and in combination with a preset proportional coefficient;

[0121] The stress distribution acquisition module 1103 is used to obtain the stress field distribution result of the target to-be-tested object by processing the equivalent stress values of all parts of the target to-be-tested object in combination with an interpolation algorithm;

[0122] The visualization display module 1104 is used to visually display the stress field distribution result.

[0123] This solution calculates the elastic stress energy corresponding to each part according to the acoustic emission electric signal energy of each part and in combination with a preset proportional coefficient, and obtains the stress field distribution result of the target to-be-tested object by processing the elastic stress energy of all parts within the target to-be-tested object in combination with an interpolation algorithm. Through the acquisition and processing means of acoustic emission signals, the magnitude and distribution law of the stress field of the test piece are obtained, and the stress field is calculated to achieve full stress field measurement. It can not only obtain the difference between the principal stresses but also obtain individual stresses.

[0124] It can not only calculate the stress field on the surface of the test piece but also calculate the internal stress distribution.

[0125] Optionally, in some embodiments, it further includes: a conversion ratio calculation module, configured to collect the acoustic emission electrical signal energy of the test piece through an acoustic emission device; wherein, the test piece and the target to-be-tested object are of the same type of test piece;

[0126] Calculate the elastic stress energy of the test piece;

[0127] Calculate a preset proportionality coefficient according to the acoustic emission signal energy and the elastic stress energy.

[0128] This solution realizes the conversion between acoustic emission energy and mechanical energy through the preset proportionality coefficient.

[0129] Optionally, in some embodiments, it further includes: a positioning module, configured to calculate the position of the acoustic emission source through the arrival time parameter and the signal over-threshold time parameter in the acoustic emission electrical signal, so as to obtain the part where the acoustic emission electrical signal energy value is emitted.

[0130] Optionally, in some embodiments, the interpolation algorithm includes: a plane interpolation method and a Lagrange interpolation method.

[0131] It can be understood that, in some embodiments, it may include some or all of the optional implementation manners in the above embodiments.

[0132] It should be noted that the above embodiments are product embodiments corresponding to the prior method embodiments. For the description of each optional implementation manner in the product embodiments, reference may be made to the corresponding description in the above method embodiments, which will not be elaborated here.

[0133] In another embodiment, a storage medium stores instructions, and when a computer reads the instructions, the computer is caused to execute a method for visual inversion of the stress field of coal and rock mass as described in any one of the above embodiments.

[0134] In another embodiment, an electronic device includes a processor and the storage medium described in the above embodiments, and the processor executes the instructions in the storage medium.

[0135] In some embodiments, the stress field is monitored by the photoelastic related method. This method requires the test piece to be color transparent, so it cannot directly calculate the natural coal and rock test pieces. In addition, to obtain calculable photoelastic fringes, the test piece must be square. Finally, the photoelastic method can only calculate the difference between the principal stresses and cannot obtain the individual stresses.

[0136] The existing solution also includes calculating the stress by the digital image correlation method. This method can only calculate the surface stress field and cannot calculate the internal stress distribution of the test piece.

[0137] Readers should understand that in the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0138] In several embodiments provided by this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the method embodiments described above are merely illustrative. For example, the division of steps is only a logical function division. In actual implementation, there can be other division methods. For example, multiple steps can be combined or integrated into another step, or some features can be ignored or not executed.

[0139] If the above method is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present invention. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0140] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An inversion visualization method for a stress field, characterized in that, Including: Collecting the acoustic emission electrical signal energy values of different parts of the target object to be measured during the rupture process; Calculating the equivalent stress value corresponding to each part according to the acoustic emission electrical signal energy obtained for each part and combining with a preset proportionality coefficient; Obtaining the stress field distribution result of the target object to be measured by combining the equivalent stress values of all parts of the target object to be measured and processing with an interpolation algorithm; Visualizing and displaying the stress field distribution result; The conversion of acoustic emission energy and mechanical energy specifically includes: First, calculate the acoustic emission energy according to the following formula based on the acoustic emission waveform file: Among them, W AE is the total acoustic emission energy; U is the acoustic emission voltage value t i , t j represents the time when the voltage first and last crosses the threshold voltage; The magnification factor is determined through a three-point bending test. A three-point bending specimen with a crack length of d0 and a thickness of t is set up. After the experiment, the crack length expands to d. Then the fracture energy G generated during the crack propagation process F is calculated according to the following formula: Then, calculate the ratio k of the two formulas according to the following formula, and the amplification system is the preset proportionality coefficient: Among them, W AE is the total acoustic emission energy; U is the acoustic emission voltage value; W0 is the area enclosed by the stress-strain curve during crack propagation.

2. The inversion visualization method of a stress field according to claim 1, wherein Collecting the acoustic emission electrical signal energy of the test piece through an acoustic emission device; wherein, the test piece and the target object to be measured are of the same type of test piece; Calculating the elastic stress energy of the test piece; Calculating the preset proportionality coefficient according to the acoustic emission electrical signal energy and the elastic stress energy.

3. The inversion visualization method of a stress field according to claim 1 or 2, characterized in that Also including: Calculating the position of the acoustic emission source through the arrival time parameter and the signal over-threshold time parameter in the acoustic emission electrical signal, and then obtaining the part that emits the acoustic emission electrical signal.

4. A method for inverse visualization of a stress field according to claim 1, characterized in that, The interpolation algorithm includes: plane interpolation method and Lagrange interpolation method.

5. An inversion visualization system for a stress field, which adopts an inversion visualization method for a stress field as described in claim 1, characterized in that, The system includes: an electrical signal energy acquisition module, a stress calculation module, a stress distribution acquisition module, and a visualization display module; The electrical signal energy acquisition module is used to collect the acoustic emission electrical signal energy values of different parts of the target object to be measured during the rupture process; The stress calculation module is used to calculate the equivalent stress corresponding to each part according to the acoustic emission electrical signal energy of each part and combining with a preset proportionality coefficient; The stress distribution acquisition module is used to obtain the stress field distribution result of the target object to be measured by combining the equivalent stress values of all parts of the target object to be measured and processing with an interpolation algorithm; The visualization display module is used to visually display the stress field distribution result.

6. The inversion visualization system of a stress field according to claim 5, characterized in that, Also including: A conversion ratio calculation module, which is used to collect the acoustic emission electrical signal energy of the test piece through an acoustic emission device; wherein, the test piece and the target object to be measured are of the same type of test piece; Calculating the elastic stress energy of the test piece; Calculating the preset proportionality coefficient according to the acoustic emission electrical signal energy and the elastic stress energy.

7. An inversion visualization system for a stress field according to claim 5 or 6, characterized in that, Also including: A positioning module, which is used to calculate the position of the acoustic emission source through the arrival time parameter and the signal over-threshold time parameter in the acoustic emission electrical signal, and then obtaining the part that emits the acoustic emission electrical signal energy value.

8. The inversion visualization system of a stress field according to claim 5, characterized in that, The interpolation algorithm includes: plane interpolation method and Lagrange interpolation method.

9. A storage medium, characterized in that, Instructions are stored in the storage medium, and when the computer reads the instructions, the computer executes an inverse visualization method of a stress field as described in any one of claims 1 to 4.

10. An electronic device, characterized in that, Including a processor and the storage medium described in claim 9, and the processor executes the instructions in the storage medium.

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