Strain-based Method, Device and Storage Medium for Failure Assessment of Pipeline Circumferential Welds

Abstract

The present invention relates to the technical field of oil and gas pipeline transmission, and particularly relates to a method, device and storage medium for evaluating the failure of pipeline girth welds based on strain. The present invention includes the following steps: S1. Establish a failure evaluation curve of the pipeline girth weld based on strain according to the pipeline to be evaluated; S2. Calculate the abscissa of the evaluation point; S3. Calculate the ordinate of the evaluation point; S4. According to the coordinates of the evaluation point obtained in step S2 and step S3, judge the relative position of the evaluation point and the failure evaluation curve, so as to evaluate the safety of the pipeline girth weld of the pipeline to be evaluated. The present invention accurately characterizes the influence of weld strength matching on the structural fracture behavior, breaks through the bottleneck problem that the existing method cannot be applied to the applicability evaluation of pipeline girth weld cracks under the condition of large-range yield controlled by strain load, and has the advantages of simple calculation, high precision and wide application range, which is beneficial to ensuring the operation safety of oil and gas pipelines.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas pipeline transmission, and particularly to a method, device and storage medium for evaluating the failure of pipeline girth welds based on strain. Background Art

[0002] Due to problems such as frequent occurrence of cracks, low strength matching of welds, and softening of the heat affected zone in pipeline girth welds, they are usually considered as the weak links of pipelines. In recent years, many pipeline failure accidents caused by the failure of girth welds have occurred during the pressure test and operation service stages of oil and gas pipelines at home and abroad, among which the proportion of pipeline girth weld fracture failure accidents caused by strain loads is very high.

[0003] As an important means for evaluating the applicability of defects, the failure assessment diagram method has been widely used in the industrial field; this method evaluates the structural safety state by establishing a failure assessment curve and an assessment point, and according to the position relationship between the assessment point and the assessment curve: when the assessment point is below the assessment curve, the assessment result is safe, otherwise it is unsafe. The core of the failure assessment diagram method lies in the construction of the failure assessment curve and the assessment point. According to different load characteristics, the method can be divided into a stress-based failure assessment diagram and a strain-based failure assessment diagram. At present, although the methods for constructing the failure assessment curves of the above two failure assessment diagrams are both relatively mature and reliable, there are still problems with inaccurate calculation methods in the construction of the assessment point, which may lead to non-conservative evaluation results. In recent years, research scholars have gradually proposed an optimized ultimate load and reference stress method for the accurate value-taking problem of the ultimate load when calculating the load ratio in the stress-based failure assessment diagram method; however, since the load in pipeline girth weld accidents often comes from soil displacement caused by geological disasters, which has typical strain load control characteristics, the currently established stress-based pipeline girth weld failure assessment diagram method cannot be accurately applied to the strain load control conditions, and the existing strain-based failure assessment diagram method ignores the influence of weld strength matching, resulting in very unsatisfactory optimization results. Therefore, in order to accurately evaluate the safety state of pipeline structures and ensure the safe operation of oil and gas pipelines, there is an urgent need in the current engineering for a strain-based failure assessment diagram method applicable to pipeline girth welds under the condition of large-scale yield. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, and provide a method for evaluating the failure of pipeline girth welds based on strain, which accurately characterizes the influence of weld strength matching on the structural fracture behavior by establishing a reference strain calculation model based on weld strength matching, breaks through the bottleneck problem that the existing method cannot be applied to the applicability evaluation of pipeline girth weld cracks under the condition of large-scale yield controlled by strain loads, and has the advantages of simple calculation, high precision and wide application range, which is beneficial to ensuring the operation safety of oil and gas pipelines.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for evaluating the failure of a pipeline girth weld based on strain, characterized by comprising the following steps:

[0007] S1. According to the pipeline to be evaluated, establish a failure evaluation curve of the pipeline girth weld based on strain;

[0008] S2. Calculate the abscissa of the evaluation point, including the following sub-steps:

[0009] S21. Calculate the reference strain ε of the pipeline to be evaluated by the following formula ref :

[0010]

[0011] Wherein:

[0012]

[0013] ξ1 = -32.665, ξ2 = 4.635, ξ3 = 0.278, ξ4 = -1.679, ξ5 = 0.979, ξ6 = 0.020, ξ7 = 1.111, ξ8 = -1.370, ξ9 = 0.402, ξ 10 = 15.781, ξ 11 = -31.787, ξ 12 = 4.292, ξ 13 = 0.307;

[0014] m is the weld strength matching coefficient;

[0015] ε u is the nominal strain received by the pipeline to be evaluated;

[0016] a is the crack depth of the pipeline to be evaluated;

[0017] t is the wall thickness of the pipeline to be evaluated;

[0018] c is half of the crack length;

[0019] n is the hardening coefficient;

[0020] D is the outer diameter of the pipeline to be evaluated;

[0021] S22. Obtain the abscissa Q of the evaluation point by the following formula r :

[0022]

[0023] Wherein:

[0024] ε0 is the strain corresponding to the material yield strength σ0;

[0025] S3. Calculate the ordinate of the evaluation point;

[0026] S4. Based on the coordinates of the evaluation point obtained in steps S2 and S3, determine the relative position of the evaluation point and the failure evaluation curve, so as to evaluate the safety of the girth weld of the pipeline to be evaluated.

[0027] Preferably, step S3 includes the following sub-steps:

[0028] S31. According to the stress-strain curve of the pipe to be evaluated, find the stress value σ u corresponding to the strain ε u , and then calculate the elastic fracture parameter J with the following formula e :

[0029]

[0030] Where:

[0031] v is the Poisson's ratio;

[0032] E is the elastic modulus of the pipe;

[0033] And:

[0034]

[0035]

[0036] When 0 < a / 2c ≤ 0.5, M1 = 1.13 - 0.09(a / c), M2 = [0.89 / (0.2 + a / c)] - 0.54, M3 = 0.5 - [1 / (0.65 + a / c)] + 14[1 - (a / c)] 24 , M4 = 1, M5 = [1 + 1.464(a / c) 1.65 0.5 ;

[0037] When 0.5 < a / 2c ≤ 1, M1 = (c / a) 0.5 [1 + 0.04c / a], M2 = 0.2(c / a) 4 , M3 = -0.11(c / a) 4 , M4 = (c / a) 0.5 , M5 = [1 + 1.464(c / a) 1.65 0.5 ;

[0038] S32. Calculate the ordinate K of the evaluation point with the following formula r :

[0039]

[0040] ​​Where: J mat is the fracture toughness of the weld.

[0041] Preferably, in the step S4, the judgment of the relative position of the evaluation point and the failure evaluation curve includes: plotting the evaluation point on the failure assessment diagram. If the evaluation point (Q r , K r ) is located below the failure evaluation curve, the girth weld of the pipeline to be evaluated is safe; otherwise, it is unsafe.

[0042] Preferably, in the step S1, before establishing the strain-based failure evaluation curve, first determine the outer diameter D, wall thickness t, outer radius R, crack depth a, crack length 2c, weld strength matching coefficient m, fracture toughness J mat of the pipeline to be evaluated, elastic modulus E of the pipe material, Poisson's ratio v, yield strength σ0 of the pipe material, hardening coefficient n, and the nominal strain ε n received by the pipeline to be evaluated; subsequently, the formula for establishing the strain-based failure evaluation curve is as follows:

[0043]

[0044] Where:

[0045] Q r is the load ratio;

[0046] σ ref is the stress corresponding to the reference strain ε ref in the material stress-strain curve;

[0047] ε0 is the strain corresponding to the material yield strength σ0.

[0048] Preferably, a device, comprising a processor, an input device, an output device, and a memory, wherein the processor, the input device, the output device, and the memory are connected in sequence, the memory is used to store a computer program, the computer program includes program instructions, and the processor is configured to call the program instructions to execute the method according to any one of claims 1 or 2 or 3.

[0049] Preferably, a storage medium, characterized in that the storage medium stores a computer program, the computer program includes program instructions, and the program instructions, when executed by a processor, cause the processor to execute the method according to any one of claims 1 or 2 or 3.

[0050] The beneficial effects of the present invention are as follows:

[0051] As can be seen from the above solution, the key point of the present invention is to propose a reference strain calculation model considering weld strength matching. By accurately positioning the coordinates of the evaluation point, especially the abscissa of the evaluation point, the model can accurately characterize the influence of weld strength matching on the structural fracture behavior. Subsequently, by replacing the reference strain model in the traditional strain-based failure assessment diagram with the proposed reference strain model, a strain-based failure assessment diagram method applicable to pipeline girth weld cracks is established.

[0052] More specifically, aiming at the deficiency that the traditional strain-based failure assessment diagram cannot consider the influence of weld strength matching on the structural fracture behavior, the present invention first introduces a weld strength matching coefficient into the reference strain calculation of the strain-based failure assessment diagram, and establishes a reference strain calculation model comprehensively considering crack size, pipeline size, yield strength and hardening characteristics of the pipe material, thereby first proposing a high-precision strain-based failure assessment diagram for pipeline girth weld cracks, breaking through the bottleneck problem that the existing methods cannot be applied to the applicability evaluation of pipeline girth weld cracks under the large-range yield condition of strain load control.

[0053] So far, the advantages of the present invention are as follows:

[0054] 1), By accurately incorporating the influence of the weld strength matching coefficient on the structural fracture behavior in the reference strain calculation method, the present invention can be applied to the fracture assessment of pipeline girth weld cracks.

[0055] 2), The present invention can be applied to the strain load control condition, thereby providing guidance for the fracture assessment of pipeline girth weld cracks under geological disaster effects.

[0056] 3), Through the present invention, the crack tolerance size of the pipeline girth weld under different load conditions can be accurately obtained, thereby providing technical support for the acceptable determination of defects in the applicability assessment of pipeline girth welds in the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 is the workflow block diagram of the present invention;

[0058] Figure 2 is the stress-strain curve of the pipe material in Example 1;

[0059] Figure 3 is the strain-based failure assessment curve in Example 1;

[0060] Figure 4 is the relative position diagram of the evaluation point and the failure assessment curve in Example 1;

[0061] Figure 5 is the schematic diagram of the connection relationship of the equipment.

[0062] The actual corresponding relationships between the reference signs and component names of the present invention are as follows:

[0063] 10 - Equipment

[0064] 11 - Processor, 12 - Memory, 13 - Input device, 14 - Output device Detailed implementation manners

[0065] For ease of understanding, in combination with Figures 1-5 , the following describes the specific implementation process of the present invention:

[0066] The method flow of the present invention is as Figure 1 shown, and specifically includes the following steps:

[0067] S1. Based on the pipeline to be evaluated, establish a failure assessment curve for the girth weld of the pipeline based on strain;

[0068] Specifically: First, determine the outer diameter D, wall thickness t, outer radius R, crack depth a, crack length 2c, weld strength matching coefficient m, weld fracture toughness J mat , elastic modulus E of the pipe material, Poisson's ratio v, yield strength σ0 of the pipe material, hardening coefficient n, and nominal strain ε to which the pipeline to be evaluated is subjected n ; Subsequently, the formula for establishing the failure assessment curve based on strain is as follows:

[0069]

[0070] Wherein:

[0071] Q r is the load ratio;

[0072] σ ref is the stress corresponding to the reference strain ε ref in the material stress-strain curve;

[0073] ε0 is the strain corresponding to the material yield strength σ0.

[0074] S2. Calculate the abscissa of the evaluation point, including the following sub-steps:

[0075] S21. Calculate the reference strain ε of the pipeline to be evaluated with the following formula ref :

[0076]

[0077] Wherein:

[0078]

[0079] ξ1 = -32.665, ξ2 = 4.635, ξ3 = 0.278, ξ4 = -1.679, ξ5 = 0.979, ξ6 = 0.020, ξ7 = 1.111, ξ8 = -1.370, ξ9 = 0.402, ξ 10 = 15.781, ξ 11 = -31.787, ξ 12 = 4.292, ξ 13 = 0.307;

[0080] m is the weld strength matching coefficient;

[0081] ε u is the nominal strain applied to the pipeline to be evaluated;

[0082] a is the crack depth of the pipeline to be evaluated;

[0083] t is the wall thickness of the pipeline to be evaluated;

[0084] c is half of the crack length;

[0085] n is the hardening coefficient;

[0086] D is the outer diameter of the pipeline to be evaluated;

[0087] S22. Obtain the abscissa Q of the evaluation point with the following formula r :

[0088]

[0089] Where:

[0090] ε0 is the strain corresponding to the material yield strength σ0;

[0091] S3. Calculate the ordinate of the evaluation point, including the following sub-steps:

[0092] S31. According to the stress-strain curve of the pipeline to be evaluated, find the stress value σ u corresponding to the strain ε u , and then calculate the elastic fracture parameter J with the following formula e :

[0093]

[0094] Where:

[0095] v is the Poisson's ratio;

[0096] E is the elastic modulus of the pipeline material;

[0097] And:

[0098]

[0099]

[0100] The M - series parameters are intermediate parameters for calculating J e when calculating, and the values of the M - series parameters are related to the magnitude of a / 2c. a / 2c describes the crack shape and is the ratio of the crack depth a to the crack length 2c.

[0101] When 0 < a / 2c ≤ 0.5, M1 = 1.13 - 0.09(a / c), M2 = [0.89 / (0.2 + a / c)] - 0.54, M3 = 0.5 - [1 / (0.65 + a / c)] + 14[1 - (a / c)] 24 , M4 = 1, M5 = [1 + 1.464(a / c) 1.65 0.5 ;

[0102] When 0.5 < a / 2c ≤ 1, M1 = (c / a) 0.5 [1 + 0.04c / a], M2 = 0.2(c / a) 4 , M3 = - 0.11(c / a) 4 , M4 = (c / a) 0.5 , M5 = [1 + 1.464(c / a) 1.65 0.5 ;

[0103] S32. Calculate the ordinate K of the evaluation point with the following formula r :

[0104]

[0105] Where: J mat is the weld fracture toughness.

[0106] S4. According to the coordinates of the evaluation point obtained in steps S2 and S3, judge the relative position of the evaluation point and the failure evaluation curve, plot the evaluation point on the failure assessment diagram. If the evaluation point (Q r , K r ) is located below the failure evaluation curve, the girth weld of the pipeline to be evaluated is safe; otherwise, it is unsafe.

[0107] Example 1

[0108] ​​① Measure the relevant parameters of the pipeline to be evaluated and the defect: pipe diameter D = 1219 mm, wall thickness t = 22.0 mm, corresponding D / t = 55.4, crack depth a = 6.6 mm, corresponding a / t = 0.3, crack length 2c = 95.7 mm, corresponding 2c / πR = 0.05, weld strength matching coefficient m = 0.8, weld fracture toughness Jmat = 610 N / mm, yield strength of the pipe material is 500 MPa, hardening coefficient n = 0.06, nominal strains εu applied to the pipeline are 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3% respectively.

[0109] At this time, the stress-strain curve of the pipe material is as Figure 2 shown.

[0110] According to Figure 2 the stress-strain curve of the pipe material shown, a strain-based failure assessment curve can be established, as Figure 3 shown.

[0111] ② Substitute the corresponding parameter values, perform the aforementioned step S2, obtain the reference strain values corresponding to different nominal strains, and obtain the abscissa Qr of the evaluation points corresponding to different nominal strains, as shown in Table 1 below.

[0112]

[0113] Table 1

[0114] ③ Substitute the corresponding parameter values, perform the aforementioned step S3, obtain Je corresponding to different nominal strains, and then obtain the ordinate K of the evaluation points corresponding to different nominal strains r , as shown in Table 2 below.

[0115]

[0116] Table 2

[0117] ④ Plot the abscissa and ordinate of the evaluation points calculated for ε u = 0.5% - 3.0% on the same graph as the failure assessment curve, as Figure 4 shown.

[0118] It can be seen from Figure 4 that:

[0119] When ε u = 0.5% and 1.0%, the evaluation points are below the failure assessment curve, indicating that the circumferential weld of the pipeline is safe at this time.

[0120] When ε u = 1.5%, the evaluation point is just on the failure assessment curve, indicating that the critical state of fracture failure is just reached at this time.

[0121] When ε u > 1.5%, the evaluation points are all above the failure evaluation curve, indicating that the girth weld of the pipeline has failed, that is, it is unsafe.

[0122] In particular, when ε n = 1.5%, that is, when the evaluation point is just on the failure evaluation curve, the critical J-integral value corresponding to the failure of the girth weld of the pipeline calculated by the conventional finite element method is 600 N / mm. Compared with the input J mat = 610 N / mm in the parameter conditions of this article, the error is only 1.6%, indicating that this technical solution is very accurate. It can not only truly evaluate the girth weld crack with weld strength matching, but also has a very high accuracy of the evaluation result and remarkable effectiveness.

[0123] Based on the above method, the present invention also provides a device used in the present invention as Figure 5 shown; the device can be the mobile device itself, or a stand-alone device independent of it. The stand-alone device can communicate with the mobile device and the ultrasonic medical device to receive the input signals collected from them and send the selected target decision-making actions to them.

[0124] As Figure 5 shown, the device 10 includes one or more processors 11 and corresponding memories 12.

[0125] The processor 11 can be a central processing unit or other forms of processing units with data processing capabilities and / or instruction execution capabilities, and can control other components in the device 10 to perform the desired functions. The memory 12 can include one or more computer program products, and the computer program products can include various forms of computer storage media, such as volatile memory and / or non-volatile memory. The volatile memory can include, for example, random access memory (RAM) and / or cache memory, etc. The non-volatile memory can include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions can be stored on the computer storage medium, and the processor 11 can run the program instructions to implement the decision-making method of the decision-making behavior of each embodiment of the present application described above and / or other desired functions.

[0126] In the example, the device 10 may further include: an input device 13 and an output device 14, and these components are interconnected through a bus system and / or other forms of connection mechanisms (not shown). For example, the input device 13 may further include, for example, a keyboard, a mouse, and so on. The output device 14 may include, for example, a display, a speaker, a printer, and a communication network and its connected remote output devices, and so on.

[0127] Of course, for simplicity, Figure 5 only some of the components of the device 10 related to the present application are shown in the figure, and components such as buses, input / output interfaces, etc. are omitted. In addition, according to specific application scenarios, the device 10 may further include any other appropriate components.

[0128] In addition to the above methods and devices, embodiments of the present application may also extend to a computer program product, which includes computer program instructions that, when run on a processor, cause the processor to execute the steps in the decision-making method according to various embodiments of the present application described in the "Exemplary Method" section above of this specification.

[0129] The computer program product may be written in any combination of one or more programming languages for programming code to perform the operations of the embodiments of the present application. The programming languages include object-oriented programming languages such as Java, C++, etc., and also include conventional procedural programming languages such as the "C" language or similar programming languages. The programming code may be executed entirely on the user's computing device, partially on the user's device, executed as a stand-alone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0130] Furthermore, embodiments of the present application may also be a readable computer storage medium, on which computer program instructions are stored, and when the computer program instructions are run on a processor, cause the processor to execute the steps in the decision-making method according to various embodiments of the present application described in the specific implementation process section above of this specification.

[0131] The computer storage medium may adopt any combination of one or more readable media. The readable media may be a readable signal medium or a storage medium. The storage medium may include, for example, but not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or components, or any combination of the above. More specific examples of the storage medium (a non-exhaustive list) include: an electrical connection having one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0132] Certainly, for those skilled in the art, the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0133] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0134] The technologies not detailedly described in the present invention are all well-known technologies.

Claims

1. A method for evaluating the failure of a pipeline girth weld based on strain, characterized in that It includes the following steps: S1. Based on the pipeline to be evaluated, establish a failure assessment curve for the girth welds of the pipeline based on strain; S2. Calculate the abscissa of the evaluation point, including the following sub-steps: S21. Calculate the reference strain ε of the pipeline to be evaluated using the following formula ref :[[]]END]] Where: ξ1 = -32.665, ξ2 = 4.635, ξ3 = 0.278, ξ4 = -1.679, ξ5 = 0.979, ξ6 = 0.020, ξ7 = 1.111, ξ8 = -1.370, ξ9 = 0.402, ξ 10 = 15.781, ξ 11 = -31.787, ξ 12 = 4.292, ξ 13 = 0.307; m is the weld strength matching coefficient; ε u is the nominal strain suffered by the pipeline to be evaluated; a is the crack depth of the pipeline to be evaluated; t is the wall thickness of the pipeline to be evaluated; c is half of the crack length; n is the hardening coefficient; D is the outer diameter of the pipeline to be evaluated; R is the outer radius of the pipeline to be evaluated; S22. Obtain the abscissa Q of the evaluation point with the following formula r , that is, the load ratio: Where: ε0 is the strain corresponding to the material yield strength σ0; S3. Calculate the ordinate of the evaluation point; S4. According to the coordinates of the evaluation point obtained in step S2 and step S3, judge the relative position of the evaluation point and the failure assessment curve, so as to evaluate the safety of the girth welds of the pipeline to be evaluated; The said step S3 includes the following sub-steps: S31. According to the stress-strain curve of the pipe to be evaluated, find the strain ε u corresponding stress value σ u , and then calculate the elastic fracture parameter J with the following formula e : Where: v is the Poisson's ratio; E is the elastic modulus of the pipe material; And: When \(0\lt\frac{a}{2c}\leq0.5\), \(M1 = 1.13 - 0.09(\frac{a}{c})\), \(M2=\frac{0.89}{0.2+\frac{a}{c}}-0.54\), \(M3 = 0.5-\frac{1}{0.65+\frac{a}{c}}+14(1 - \frac{a}{c})\) 24 , \(M4 = 1\), \(M5=[1 + 1.464(\frac{a}{c}) 1.65 0.5 ;​ When 0.5 < a / 2c ≤ 1, M1 = (c / a) 0.5 [1 + 0.04c / a], M2 = 0.2(c / a) 4 , M3 = -0.11(c / a) 4 , M4 = (c / a) 0.5 , M5 = [1 + 1.464(c / a) 1.65 0.5 ;​ S32. Calculate the ordinate K of the evaluation point using the following formula r :[[]]END]] Where: J mat is the fracture toughness of the weld.

2. The method for evaluating the failure of a pipeline girth weld based on strain according to claim 1, wherein: In the step S4, the judgment of the relative position between the evaluation point and the failure evaluation curve includes: plotting the evaluation point on the failure assessment diagram. If the evaluation point (Q r , K r ) is located below the failure evaluation curve, the girth weld of the pipeline to be evaluated is safe; otherwise, it is unsafe.

3. A method for evaluating the failure of a pipeline girth weld based on strain, according to claim 1 or 2, characterized in that: In the step S1, before establishing the strain-based failure assessment curve, first determine the outer diameter D, wall thickness t, outer radius R, crack depth a, crack length 2c, weld strength matching coefficient m, weld fracture toughness J of the pipeline to be evaluated mat , elastic modulus E of the pipe material, Poisson's ratio v, yield strength σ0 of the pipe material, hardening coefficient n, and nominal strain ε applied to the pipeline to be evaluated u ; Subsequently, the formula for establishing the strain-based failure assessment curve is as follows: Where: Q r is the load ratio, i.e., the abscissa; σ ref is the stress corresponding to the reference strain ε ref in the material stress-strain curve; ε0 is the strain corresponding to the material yield strength σ0.

4. A device, characterized in that, It includes a processor, an input device, an output device and a memory. The processor, the input device, the output device and the memory are connected in sequence. The memory is used to store a computer program. The computer program includes program instructions. The processor is configured to call the program instructions to execute the method according to claim 1 or 2.

5. A storage medium, characterized in that, The storage medium stores a computer program. The computer program includes program instructions. When the program instructions are executed by the processor, the processor executes the method according to claim 1 or 2.

Images