Method, device and equipment for calculating fatigue life of rusted metal wire

Abstract

The invention discloses a rusty metal wire fatigue life calculation method, device and equipment, and the method comprises the steps: building a finite element calculation model of a real corrosion surface, calculating a stress concentration region of the real corrosion surface, determining the position, size and crack propagation direction of a dangerous corrosion pit, defining a damage evolution criterion and a damage criterion, and calculating the fatigue life of the rusty metal wire. And a criterion program is embedded in finite element software for calculation, and the fatigue crack initiation life and extension life of the rusted metal wire are obtained. And a CM-EIFS extrapolation method is combined with the fatigue crack initiation and propagation model to respectively calculate the fatigue crack initiation life and propagation life of the rusted metal wire, and the fatigue crack initiation life and propagation life are compared with the calculation result of the finite element calculation model to verify the correctness of the fatigue life calculated by the rusted metal wire model. By establishing the finite element calculation model considering the corrosion morphology and the crack initiation life, the calculation result of the fatigue life of the rusted metal wire is closer to the actual situation, the calculation is simple and convenient, and the precision is high.

Description

Technical Field

[0001] The invention relates to the technical field of calculation of fatigue life of corroded metal wires, and in particular to a method, device and equipment for calculating fatigue life of corroded metal wires. Background Art

[0002] Metal wire is one of the most widely used materials in the field of civil engineering. For example, important components in bridge engineering, such as cables and slings, are all made of metal wire (high-strength steel wire). However, during the service life of metal wire, it is inevitably subjected to disaster factors such as environmental erosion, fatigue effect and mutation effect, which leads to cumulative damage and fatigue resistance decline of metal wire. In particular, corrosion and fatigue cause the durability and bearing capacity of important components to decrease, which has become the main factor affecting the service life of the structure and threatening the safety of the structure in service. Therefore, it is beneficial to ensure the service safety of metal wire and avoid economic losses and casualties by efficiently and accurately calculating the fatigue life and failure position of rusted metal wire and maintaining or replacing the rusted metal wire in time.

[0003] At present, there are two main methods for fatigue life analysis of corroded metal wires:

[0004] The first method can only obtain the total fatigue life of the sample under a specific fatigue load spectrum through fatigue testing, and cannot obtain the fatigue crack initiation life and extension life respectively. Especially for rusted samples, more control groups and normal samples are required, which is economically costly and has a long test cycle. For metal wires, specific fatigue test fixtures are also required. Fatigue test results are often highly random and cannot fully meet the requirements of efficient and accurate prediction of the fatigue life of rusted metal wires.

[0005] Another method is through numerical simulation. The current calculation method often only obtains the total fatigue life of the rusted specimen, and cannot separately solve the initiation life and extension life in the fatigue failure process. Some prediction methods ignore the setting of the fatigue crack initiation threshold. Most of them are only applicable to low-cycle fatigue and cannot accurately solve the medium and high-cycle fatigue life. The fatigue life prediction objects are mostly plates, and the wire surface is more complex, so the prediction method is difficult to apply, and the prediction method has not verified its effectiveness.

[0006] In the prior art, Chinese patent CN116306153B discloses a fatigue life calculation method for rusted steel plates based on three-dimensional point clouds, including obtaining surface point clouds of rusted steel plates; denoising and removing impurities from the surface point clouds, and interpolating them into a corrosion depth matrix; establishing a finite element static tensile calculation basic model M1; assigning the corrosion depth matrix to the surface units of the basic model M1 to obtain a real surface finite element static calculation model M2, and calculating its strain concentration area and stress concentration area; predicting the position of its crack initiation area to set a Seam, and its Seam can be set close to the rust pit contour to generate a finite element crack calculation basic model M3; assigning the corrosion depth matrix to the surface units of M3 to obtain a stress intensity factor finite element calculation model M4, and calculating the stress intensity factor at the crack tip; calculating fatigue life by using the Paris formula and its related formulas; using the Paris formula to calculate the crack propagation rate, obtaining a new crack size and performing repeated calculations of steps A5-A7 to calculate the fatigue life of the rusted steel plate.

[0007] However, fatigue life is a complex process involving multiple stages. The above method only calculates fatigue life based on fatigue crack growth rate and ignores fatigue crack initiation life, which may lead to inaccurate calculation results. In particular, the calculation error of medium and high cycle fatigue life (the initiation life stage accounts for a large proportion of the time) is large and its accuracy cannot be guaranteed.

[0008] Secondly, the above method is only applicable to corroded metal sheets, and the above depth assignment method cannot be directly applied to corroded metal wires.

[0009] Finally, there is a lack of theoretical analysis and calculation for the fatigue crack initiation and extension life analysis method of rusted metal wires, and the accuracy of the finite element analysis calculation model has not been verified. Summary of the invention

[0010] Based on this, in order to solve the technical problem of inaccurate calculation of the fatigue life of metal wires in the prior art, the present invention proposes a method, device and equipment for calculating the fatigue life of rusted metal wires.

[0011] A method for calculating fatigue life of corroded metal wire, comprising:

[0012] S1. Obtaining point cloud data of the surface of the corroded metal wire, coloring, denoising, and surfacing the point cloud data to obtain a geometric model of the corroded metal wire;

[0013] S2, calculating the stress distribution in the geometric model of the corroded metal wire to obtain the stress concentration area; extracting the corrosion pit position of the corroded metal wire from the stress concentration area, and setting the cross-sectional shape contour of the corrosion pit position of the corroded metal wire as the initial crack size;

[0014] S3, adding the corrosion pit position and initial crack size of the corroded metal wire to the corroded metal wire geometric model obtained in step S1 to obtain a corrosion pit calculation model of the corroded metal wire;

[0015] S4, based on the corrosion pit calculation model and fracture mechanics calculation formula of the corroded metal wire obtained in step S3, respectively define the fatigue crack initiation, extension damage criteria and fracture criteria of the corroded metal wire, and finally, embed the criterion program in the finite element software to calculate and obtain the fatigue crack initiation life N1 and fatigue crack extension life N2 of the corroded metal wire;

[0016] S5. Fatigue test of corroded metal wire to obtain the surface morphology of the corroded fracture and fatigue life. Based on the fatigue of the corroded metal wire and the fatigue test results of the corroded metal wire, the extrapolation method of CM-EIFS is used to calculate the fatigue crack initiation life N3 and fatigue crack propagation life N4 of the corroded metal wire respectively.

[0017] S6. Compare the fatigue crack initiation life N1 with the fatigue crack initiation life N3, and the fatigue crack growth life N2 with the fatigue crack growth life N4 to verify the correctness of the calculation of fatigue crack initiation and growth life by the established finite element analysis model of the corroded metal wire.

[0018] Step S2 calculates the stress distribution in the geometric model of the corroded metal wire to obtain the stress concentration area, which specifically includes the following sub-steps:

[0019] S21, meshing the geometric model of the corroded metal wire to obtain a finite element calculation model of the corroded metal wire;

[0020] S22. Calculate the stress distribution of the finite element calculation model of the corroded metal wire based on the material elastic modulus, Poisson's ratio, and stress-strain data of the corroded metal wire.

[0021] The stress-strain data in step S22 is obtained by converting the engineering stress-strain data into real stress-strain data:

[0022] σ T =σ nom (1+ε nom )

[0023] ε T =ln(1+ε nom )

[0024] In the formula, σ T and ε T are the true stress data and true strain data respectively;

[0025] σ nom and ε nom They are nominal stress data and nominal strain data respectively;

[0026] In() represents a logarithmic operation.

[0027] Step S4 specifically includes the following sub-steps:

[0028] S41. Define the damage criteria for fatigue crack initiation and expansion of corroded metal wire according to the Paris formula:

[0029] when When the rusted metal wire is in the fatigue crack initiation stage, When the fatigue crack propagates, G th <G max <G pl , the corresponding crack extension satisfies

[0030] S42, Fatigue failure criterion of corroded metal wire: When G c ≤G max , fracture damage occurs;

[0031] S43, solving the above formula to obtain the fatigue crack initiation life N1 and fatigue crack growth life N2 of the corroded metal wire;

[0032] Where, f is the ratio of the number of cycles obtained by finite element calculation to the number of cycles when the fatigue crack growth life is reached;

[0033] N is the number of cycles obtained by finite element calculation;

[0034] ΔG is the energy release rate at the crack tip during the cycle;

[0035] G th is the strain energy release rate threshold;

[0036] G pl is the upper limit of strain energy release rate;

[0037] G c is the critical equivalent strain energy release rate;

[0038] G max is the maximum energy release rate at the crack tip;

[0039] a is the crack extension depth;

[0040] da means partial derivative of a;

[0041] dN means partial derivative with respect to N;

[0042] C1, C2, C3 and C4 are material constants related to the energy release rate.

[0043] The material constants are obtained by the following formula,

[0044]

[0045] C3=C4=m / 2

[0046] Where C and m are the relevant material constants in the microcrack initiation and macrocrack propagation models, which are obtained according to tests or specifications;

[0047] E' is the elastic modulus;

[0048] K t is the stress concentration factor.

[0049] The step S1 of obtaining the surface point cloud data of the corroded metal wire comprises the following sub-steps:

[0050] S11, using a non-contact surface profiler to scan the rust on the surface of the metal wire multiple times and at multiple angles to obtain point cloud data of the rust on the surface of the metal wire;

[0051] S12. The metal wire surface corrosion point cloud data at different angles are converted into the same coordinate system through the set reference point. The conversion formula is as follows:

[0052]

[0053] Where x0, y0 and z0 are three translation parameters, three-dimensional vectors;

[0054] a 11 、a 12 、a 13 、a 21 、a 22 、a 23 、a 31 、a 32 and a 33 They are nine direction cosines, a third-order matrix;

[0055] S13. Based on the Kriging method, the metal wire surface corrosion point cloud data in the same coordinate system is standardized and matrix-aligned to obtain point cloud data for constructing a metal wire geometric model.

[0056] The step S43 of obtaining the fatigue crack initiation life N1 and the fatigue crack growth life N2 of the corroded metal wire specifically includes the following steps:

[0057] S431, embedding the damage criterion and the destruction criterion into the corrosion pit calculation model of the corroded metal wire, performing fatigue crack initiation and propagation analysis, and obtaining the fatigue crack initiation life N1 and fatigue crack propagation life N2 of the corroded metal wire;

[0058] S432. In the fatigue crack initiation and propagation analysis, additional terms - step expansion and crack tip expansion terms are introduced to approximate the discontinuous field around the crack, where the step expansion term is used to characterize the unit completely cut by the crack, and the crack tip expansion term is used to characterize the unit partially divided by the crack.

[0059] Step S5 specifically includes the following sub-steps:

[0060] S51, fatigue test of corroded metal wire to obtain the surface morphology of the corroded fracture and fatigue life;

[0061] S52. Based on the EIFS method, the fracture observation method is used to take the dangerous pit at the fatigue source of the rust fracture as the initial equivalent initial crack size;

[0062] S53, using the extrapolation method and the corresponding fatigue crack initiation and propagation model to calculate, by adjusting the initial crack size to make the theoretical life of the numerical simulation close to the test result;

[0063] S54, thereby estimating the equivalent initial crack depth, i.e., the estimated value of CM-EIFS, the fatigue crack initiation life N3, and the fatigue crack growth life N4.

[0064] The present invention further discloses a device for calculating fatigue life of corroded metal wire, comprising:

[0065] A data acquisition module is used to obtain point cloud data on the surface of the corroded metal wire and to surface the point cloud data to obtain a geometric model of the corroded metal wire;

[0066] The pit acquisition module is used to calculate the stress distribution in the geometric model of the corroded metal wire and obtain the stress concentration area; extract the pit position of the corroded metal wire from the stress concentration area, and set the cross-sectional shape contour of the pit position of the corroded metal wire to set it as the initial crack size;

[0067] A life calculation module is used to add the corrosion pit position and initial crack size of the corroded metal wire to the geometric model of the corroded metal wire to obtain the corrosion pit calculation model of the corroded metal wire; based on the corrosion pit calculation model of the corroded metal wire and the fracture mechanics calculation formula, the fatigue crack initiation life N1 and fatigue crack extension life N2 of the corroded metal wire are obtained;

[0068] Verify the calculation module, use the CM-EIFS extrapolation method combined with the fatigue crack initiation and growth model to calculate the fatigue crack initiation life N3 and fatigue crack growth life N4 of the corroded metal wire respectively;

[0069] The comparison verification module compares the fatigue crack initiation life N1 with the fatigue crack initiation life N3, and the fatigue crack growth life N2 with the fatigue crack growth life N4, to verify the correctness of the calculation of fatigue crack initiation and growth life by the established finite element analysis model of corroded metal wire.

[0070] The present invention further discloses a computing device, comprising at least one processor and a memory;

[0071] The memory stores computer-executable instructions;

[0072] At least one of the processors executes the computer-executable instructions stored in the memory, so that at least one of the processors executes the method for calculating the fatigue life of a corroded metal wire.

[0073] At least one of the above technical solutions adopted in this specification can achieve the following beneficial effects:

[0074] In the method for calculating the fatigue life of a corroded metal wire provided in this specification, the above method has the following advantages in calculating the fatigue crack initiation life and propagation life of the corroded metal wire:

[0075] The present invention calculates the fatigue life based on the initiation life and the extension life of fatigue cracks, thereby obtaining a more accurate life calculation result. Specifically: the behavior of the material in the fatigue crack initiation and extension stages may be different, and considering them in stages can more accurately describe these behaviors. By combining the life of the two stages, the present invention can improve the reliability of the prediction and reduce the uncertainty of a single model or hypothesis.

[0076] In addition, since the depth assignment method cannot be directly applied to metal wires, the present invention uses Geomagic Studio reverse engineering software to process the point cloud data and obtain a geometric model. The modeling method is simple and at the same time ensures a reconstruction accuracy of up to 0.01mm. The geometric model can be directly imported into the finite element software for calculation and analysis, and the operation is quick. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 A schematic diagram of a method for calculating fatigue life of a corroded metal wire provided by the present invention;

[0078] Figure 2 A finite element calculation flow chart of fatigue crack initiation and growth life of a corroded metal wire provided by the present invention;

[0079] Figure 3 The framework diagram of the fatigue life theory calculation based on the extrapolation method of the CM-EIFS model provided by the present invention;

[0080] Figure 4 It is a point cloud image of corroded metal wire;

[0081] Figure 5 It is a diagram of the packaging of rusted metal wire;

[0082] Figure 6 It is a geometric model diagram of rusted metal wire;

[0083] Figure 7 It is a finite element calculation model diagram of corroded metal wire;

[0084] Figure 8 This is the static calculation result diagram of the corroded metal wire;

[0085] Fig. 9 It is the pit diagram at the maximum stress position of the corroded metal wire;

[0086] Fig.10 It is an equivalent treatment of etch pits;

[0087] Fig.11 It is a comparison chart between the theoretical calculated value and the finite element calculated value of the fatigue crack initiation and growth life of the corroded metal wire;

[0088] Fig.12 It is a comparison between the finite element calculation failure diagram of the rusted metal wire and the fatigue test failure diagram. DETAILED DESCRIPTION

[0089] In order to make the purpose, technical solutions and advantages of this specification more clear, the technical solutions of the present invention will be clearly and completely described below in combination with the specific embodiments of this specification and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments in the specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0090] The present invention proposes a method for calculating the fatigue life of a corroded metal wire. The method establishes a finite element calculation model of a real corrosion surface, calculates its stress concentration area, thereby determining the location, size and crack propagation direction of a dangerous pit, and defines a damage evolution criterion and a failure criterion. A criterion program is embedded in the finite element software to calculate and obtain the fatigue crack initiation life N1 and fatigue crack propagation life N2 of the corroded metal wire.

[0091] The corroded metal wires were tested through fatigue experiments, and the extrapolation method of CM-EIFS combined with the fatigue crack initiation and propagation model was used to calculate the crack initiation life and propagation life of the corroded metal wires respectively. The results were compared with the calculation results of the finite element calculation model to verify the correctness of the fatigue life calculation of the constructed corroded metal wire model.

[0092] The present invention establishes a finite element calculation model that takes into account the corrosion morphology and crack initiation life, so that the calculation results of the fatigue life of rusted metal wires are closer to the actual situation. The model is simple to establish and calculate with high accuracy, and can be used repeatedly for calculation, which has strong use value. Due to the special curved surface shape of the wire, the depth assignment method cannot be directly applied to curved surface materials. Therefore, the accuracy and application of corrosion surface acquisition are relatively lacking. At the same time, a theoretical calculation method for the fatigue crack initiation and extension life of rusted metal wires is provided, and compared with the finite element calculation results and test results, which further proves the accuracy of the finite element calculation method; when calculating the fatigue life, the present invention takes into account the initiation life of fatigue cracks, and can be well applied in the calculation of low-cycle fatigue or medium- and high-cycle fatigue life.

[0093] Figure 1 The process of the method for calculating the fatigue life of the corroded metal wire in this embodiment is shown. Figure 1 The fatigue life calculation method of the corroded metal wire is described in detail, which specifically includes the following steps:

[0094] A1: Establish a finite element calculation model of the real corrosion surface:

[0095] Obtain the surface morphology point cloud data of the corroded metal wire, and perform standardization, denoising, packaging and other processing on the point cloud data, and perform surface precision on the processing results, and finally obtain the geometric model M1 of the corroded metal wire, and import it into the finite element software to generate the finite element calculation model M2 of the corroded metal wire. Specifically:

[0096] A non-contact surface topography instrument with a scanning accuracy of 0.01 mm was used to scan the surface rust of the metal wire multiple times and at multiple angles to obtain the point cloud data of the surface rust of the metal wire. The point cloud data of the surface rust of the metal wire at different angles were converted into the same coordinate system through the set reference points. Based on Kriging, the scanned point cloud data in the same coordinate system were standardized, and the upper and lower surface data of the rusted steel wire were aligned in a matrix to obtain the point cloud data for constructing the geometric model of the metal wire. Finally, Geomagic Studio reverse engineering software was used to process the point cloud data and obtain the geometric model M1.

[0097] A2: Define the material properties of the finite element calculation model M2, including: material elastic modulus, Poisson's ratio, and stress-strain relationship. Specifically:

[0098] Stress-strain data is obtained by converting engineering stress-strain data into real stress-strain data:

[0099] σ T =σ nom (1+ε nom )

[0100] εT =ln(1+ε nom )

[0101] Where σ T and ε T are the true stress data and true strain data respectively; σ nom and ε nom are nominal stress and strain values ​​respectively; In() represents logarithmic operation.

[0102] A3: Based on the finite element calculation model M2, calculate its stress concentration area; the finite element calculation model M2 and the finite element calculation model M3 adopt hexahedral C3D8R units for meshing, and improve the analysis accuracy through the transitional mesh technology.

[0103] A4: Determine the location of the dangerous pit, extract the cross-sectional shape of the pit and set it as the initial crack size Mcrack, generate a finite element calculation model M3 containing the initial crack size model, and determine the crack extension direction. Specifically:

[0104] According to the position of the dangerous pit, the coordinate data of the dangerous pit contour curve is accurately extracted based on the standardized point cloud data, the initial crack size Mcrack is generated, and inserted into the corresponding position in the finite element calculation model M3.

[0105] A5: Define the damage criterion and failure criterion of the finite element calculation model M3:

[0106] According to the Paris energy law, when When (ΔG is the energy release rate at the crack tip under the cycle), the fatigue crack propagates. At this time, G th <G max <G pl (G th is the strain energy release rate threshold, G pl is the upper limit of strain energy release rate), the corresponding crack extension satisfies Until G is satisfied c ≤G max (Critical equivalent strain energy release rate G c ), fracture occurs. C1, C2, C3, C4 are material constants related to energy release rate.

[0107] Among them, based on the relationship between energy release rate and stress intensity factor, the C1, C2, C3, and C4 energy release rate material constants are converted. Specifically:

[0108] Based on the scope of linear elastic fracture mechanics, the relationship between energy release rate and stress intensity factor is converted into ΔG=ΔK 2 / E' (△K is the amplitude of stress intensity factor), and according to the relevant material constants C and m in the microcrack initiation and macro crack propagation model, the conversion relationship between the C1, C2, C3, C4 energy release rate material constants and C and m is obtained:

[0109]

[0110] C3=C4=m / 2

[0111] In the formula, K t is the stress concentration factor, E' is the elastic modulus. Material constants C and m can be obtained according to tests or specifications.

[0112] A6: Generate a finite element calculation model M3 for fatigue life calculation and analysis of corroded metal wire. Specifically:

[0113] The damage criterion and the destruction criterion are embedded into the finite element calculation model M3 through the code, and the fatigue crack initiation and propagation analysis is carried out to obtain the fatigue crack initiation life and propagation life of the corroded metal wire. In the fatigue crack initiation and propagation analysis, the additional terms - step expansion and crack tip expansion terms are introduced to approximate the discontinuous field around the crack, where the step expansion term is used to characterize the unit completely cut by the crack, and the crack tip expansion term is used to characterize the unit partially divided by the crack.

[0114] A7: Calculate the fatigue crack initiation life N1 and fatigue crack growth life N2 of the corroded metal wire according to the finite element calculation model M3;

[0115] A8: Fatigue test of corroded metal wire to obtain the surface morphology of the corroded fracture and fatigue life. Based on the test results, the CM-EIFS extrapolation method is used to calculate the crack initiation and propagation life of the corroded metal wire. Specifically:

[0116] The CM-EIFS extrapolation method is based on the EIFS method. It uses the fracture observation method, takes the dangerous pit at the fatigue source as the initial equivalent initial crack size, adopts the extrapolation method, and uses the corresponding crack initiation and propagation model to calculate. By adjusting the initial crack size, the theoretical life of the numerical simulation is close to the experimental result. The equivalent initial crack depth, i.e. the CM-EIFS estimated value, the fatigue crack initiation life N3, and the propagation life N4 are estimated. The crack initiation life includes the crack nucleation life and the microcrack propagation life, and the crack propagation model is the Paris macro crack propagation model.

[0117] A9: Compare the fatigue crack initiation life N1 with the fatigue crack initiation life N3, and the fatigue crack growth life N2 with the fatigue crack growth life N4 to verify the correctness of the fatigue life calculation of the established rusted metal wire model.

[0118] The specific definition of the device for calculating the fatigue life of a corroded metal wire can be found in the definition of the method for calculating the fatigue life of a corroded metal wire mentioned above, and will not be repeated here. Each module in the above-mentioned device for calculating the fatigue life of a metal wire can be implemented in whole or in part by software, hardware, and a combination thereof. Each of the above-mentioned modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute the operations corresponding to each of the above modules.

[0119] This specification also provides the structure of a computer device. At the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory. Of course, it may also include other hardware required for the business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to achieve the above Figure 1 A method for calculating the fatigue life of rusted metal wire is provided.

[0120] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this specification can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0121] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for calculating fatigue life of corroded metal wire, characterized in that: include: S1. Obtaining point cloud data of the surface of the corroded metal wire, coloring, denoising, and surfacing the point cloud data to obtain a geometric model of the corroded metal wire; S2, calculating the stress distribution in the geometric model of the corroded metal wire obtained in step S1 to obtain a stress concentration area; extracting the corrosion pit position of the corroded metal wire from the stress concentration area, and setting the cross-sectional shape contour of the corrosion pit position of the corroded metal wire as the initial crack size; S3, adding the corrosion pit position and initial crack size of the corroded metal wire to the corroded metal wire geometric model obtained in step S1 to obtain a corrosion pit calculation model of the corroded metal wire; S4, based on the corrosion pit calculation model and fracture mechanics calculation formula of the corroded metal wire obtained in step S3, respectively define the fatigue crack initiation, extension damage criteria and fracture criteria of the corroded metal wire, and finally, embed the criterion program in the finite element software for calculation to obtain the fatigue crack initiation life N1 and fatigue crack extension life N2 of the corroded metal wire; S5. Fatigue test of corroded metal wire to obtain the surface morphology of the corroded fracture and fatigue life. Based on the fatigue test results of the corroded metal wire, the extrapolation method of CM-EIFS is used to calculate the fatigue crack initiation life N3 and fatigue crack propagation life N4 of the corroded metal wire respectively; S6. Compare the fatigue crack initiation life N1 with the fatigue crack initiation life N3, and the fatigue crack growth life N2 with the fatigue crack growth life N4 to verify the correctness of the calculation of fatigue crack initiation and growth life by the established finite element analysis model of the corroded metal wire.

2. The method for calculating fatigue life of a corroded metal wire according to claim 1, characterized in that: Step S2 calculates the stress distribution in the geometric model of the corroded metal wire to obtain the stress concentration area, which specifically includes the following sub-steps: S21, meshing the geometric model of the corroded metal wire to obtain a finite element calculation model of the corroded metal wire; S22. Calculate the stress distribution of the finite element calculation model of the corroded metal wire based on the material elastic modulus, Poisson's ratio, and stress-strain data of the corroded metal wire.

3. The method for calculating fatigue life of a corroded metal wire according to claim 2, characterized in that: The stress-strain data in step S22 is obtained by converting the engineering stress-strain data into real stress-strain data: s T =s nom (1+e nom ) e T =ln(1+ε nom ) In the formula, σ T and ε T are the true stress data and true strain data respectively; σ nom and ε nom They are nominal stress data and nominal strain data respectively; In() represents a logarithmic operation.

4. The method for calculating fatigue life of a corroded metal wire according to claim 1, characterized in that: Step S4 specifically includes the following sub-steps: S41. Define the damage criteria for fatigue crack initiation and expansion of corroded metal wire according to the Paris formula: when When the rusted metal wire is in the fatigue crack initiation stage, When the fatigue crack propagates, G th <G max <G pl , the corresponding crack extension satisfies S42, Fatigue failure criterion of corroded metal wire: When G c ≤G max , fracture damage occurs; S43, solving the above formula to obtain the fatigue crack initiation life N1 and fatigue crack growth life N2 of the corroded metal wire; Where, f is the ratio of the number of cycles obtained by finite element calculation to the number of cycles when the fatigue crack growth life is reached; N is the number of cycles obtained by finite element calculation; ΔG is the energy release rate at the crack tip during the cycle; G th is the strain energy release rate threshold; G pl is the upper limit of strain energy release rate; G c is the critical equivalent strain energy release rate; G max is the maximum energy release rate at the crack tip; a is the crack extension depth; da means partial derivative of a; dN means partial derivative with respect to N; C1, C2, C3 and C4 are material constants related to the energy release rate.

5. The method for calculating fatigue life of a corroded metal wire according to claim 4, characterized in that: The material constants are obtained by the following formula, C3=C4=m / 2 Where C and m are the relevant material constants in the microcrack initiation and macrocrack propagation models, which are obtained according to tests or specifications; E' is the elastic modulus; K t is the stress concentration factor.

6. The method for calculating fatigue life of a corroded metal wire according to claim 1, characterized in that: The step S1 of obtaining the surface point cloud data of the corroded metal wire comprises the following sub-steps: S11, using a non-contact surface profiler to scan the rust on the surface of the metal wire multiple times and at multiple angles to obtain point cloud data of the rust on the surface of the metal wire; S12. The metal wire surface corrosion point cloud data at different angles are converted into the same coordinate system through the set reference point. The conversion formula is as follows: Where x0, y0 and z0 are three translation parameters, three-dimensional vectors; a 11 、a 12 、a 13 、a 21 、a 22 、a 23 、a 31 、a 32 and a 33 They are nine direction cosines, a third-order matrix; S13. Based on the Kriging method, the metal wire surface corrosion point cloud data in the same coordinate system is standardized and matrix-aligned to obtain point cloud data for constructing a metal wire geometric model.

7. The method for calculating fatigue life of a corroded metal wire according to claim 4, characterized in that: The step S43 of obtaining the fatigue crack initiation life N1 and the fatigue crack growth life N2 of the corroded metal wire specifically includes the following steps: S431, embedding the damage criterion and the destruction criterion into the corrosion pit calculation model of the corroded metal wire, performing fatigue crack initiation and propagation analysis, and obtaining the fatigue crack initiation life N1 and fatigue crack propagation life N2 of the corroded metal wire; S432. In the fatigue crack initiation and propagation analysis, additional terms - step expansion and crack tip expansion terms are introduced to approximate the discontinuous field around the crack, where the step expansion term is used to characterize the unit completely cut by the crack, and the crack tip expansion term is used to characterize the unit partially divided by the crack.

8. The method for calculating fatigue life of a corroded metal wire according to claim 1, characterized in that: Step S5 specifically includes the following sub-steps: S51, fatigue test of corroded metal wire to obtain the surface morphology of the corroded fracture and fatigue life; S52. Based on the EIFS method, the fracture observation method is used to take the dangerous pit at the fatigue source of the rust fracture as the initial equivalent initial crack size; S53, using the extrapolation method and the corresponding fatigue crack initiation and propagation model to calculate, by adjusting the initial crack size to make the theoretical life of the numerical simulation close to the test result; S54, thereby estimating the equivalent initial crack depth, i.e., the estimated value of CM-EIFS, the fatigue crack initiation life N3, and the fatigue crack growth life N4.

9. A device for calculating fatigue life of corroded metal wire, characterized in that: include: A data acquisition module is used to obtain point cloud data on the surface of the corroded metal wire and to surface the point cloud data to obtain a geometric model of the corroded metal wire; The pit acquisition module is used to calculate the stress distribution in the geometric model of the corroded metal wire and obtain the stress concentration area; extract the pit position of the corroded metal wire from the stress concentration area, and set the cross-sectional shape contour of the pit position of the corroded metal wire to set it as the initial crack size; A life calculation module is used to add the corrosion pit position and initial crack size of the corroded metal wire to the geometric model of the corroded metal wire to obtain the corrosion pit calculation model of the corroded metal wire; based on the corrosion pit calculation model of the corroded metal wire and the fracture mechanics calculation formula, the fatigue crack initiation life N1 and fatigue crack extension life N2 of the corroded metal wire are obtained; Verify the calculation module, use the CM-EIFS extrapolation method combined with the fatigue crack initiation and growth model to calculate the fatigue crack initiation life N3 and fatigue crack growth life N4 of the corroded metal wire respectively; The comparison verification module compares the fatigue crack initiation life N1 with the fatigue crack initiation life N3, and the fatigue crack growth life N2 with the fatigue crack growth life N4, to verify the correctness of the calculation of fatigue crack initiation and growth life by the established finite element analysis model of corroded metal wire.

10. A computing device, characterized in that comprising at least one processor and a memory; The memory stores computer-executable instructions; At least one of the processors executes the computer-executable instructions stored in the memory, so that at least one of the processors executes the method for calculating the fatigue life of a corroded metal wire as described in any one of claims 1 to 8.

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