A method, device and equipment for calculating fatigue life of corroded metal wire

Abstract

The present invention discloses a method, device and equipment for calculating the fatigue life of a corroded metal wire. The method establishes a finite element calculation model of a real corroded surface and calculates its stress concentration area, thereby determining the location, size and crack propagation direction of dangerous pits, and defining damage evolution criteria and failure criteria. The criterion program is embedded in the finite element software for calculation to obtain the fatigue crack initiation life and propagation life of the corroded metal wire. The CM-EIFS extrapolation method is used in combination with the fatigue crack initiation and propagation model to calculate the fatigue crack initiation life and propagation life of the corroded metal wire, respectively, and 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. By establishing a finite element calculation model that takes into account the corrosion morphology and crack initiation life, the present invention makes the calculation results of the fatigue life of the corroded metal wire closer to the actual situation, and the calculation is simple and the accuracy is high.

Description

Technical Field

[0001] The present 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 the fatigue life of corroded metal wires. Background Art

[0002] Metal wire is one of the most widely used materials in civil engineering. For example, important components in bridge engineering, such as cables and suspenders, are all made of metal wire (high-strength steel wire). However, during their service life, metal wire is inevitably subjected to hazards such as environmental erosion, fatigue effects, and mutation effects, resulting in cumulative damage and fatigue resistance failure of the metal wire. In particular, corrosion and fatigue reduce the durability and bearing capacity of important components, which has become a major factor affecting the service life of structures and threatening their service safety. Therefore, efficiently and accurately calculating the fatigue life and failure location of corroded metal wire and promptly maintaining or replacing the corroded metal wire will help ensure the service safety of the metal wire and avoid economic losses and casualties.

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

[0004] The first method, through fatigue testing, often only provides the total fatigue life of a specimen under a specific fatigue load spectrum, but cannot separately determine the fatigue crack initiation life and fatigue crack propagation life. This is particularly true for corroded specimens, as it requires a large number of control groups and regular specimens, resulting in high costs and long test cycles. Specific fatigue test fixtures are also required for metal wires, and fatigue test results often exhibit significant randomness, making it impossible to fully and efficiently predict the fatigue life of corroded metal wires.

[0005] Another method is through numerical simulation. The current calculation methods often only obtain the total fatigue life of the rusted specimens, 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, comprising obtaining a surface point cloud of the rusted steel plate; denoising and removing impurities from the surface point cloud, and interpolating it into a corrosion depth matrix; establishing a finite element static tensile calculation basic model M1; assigning the corrosion depth matrix to the surface elements 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 and setting a Seam, which 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 elements 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 using the Paris formula and its related formulas; calculating the crack propagation rate using the Paris formula, obtaining a new crack size, and repeating 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 the fatigue crack growth rate, ignoring the fatigue crack initiation life, which may lead to inaccurate calculation results. In particular, the calculation error for 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 plates, 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 analysis method of fatigue crack initiation and extension life 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 the fatigue life of a 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. Calculate the stress distribution in the geometric model of the corroded metal wire to obtain a stress concentration area; extract the location of the corrosion pit of the corroded metal wire from the stress concentration area, and set the cross-sectional shape contour of the corrosion pit 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 geometric model of the corroded metal wire 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 obtained in step S3, fatigue crack initiation and growth damage criteria and fracture criteria of the corroded metal wire are defined respectively. Finally, the criterion program is embedded in the finite element software to calculate and obtain the fatigue crack initiation life N1 and fatigue crack growth 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 test results of the corroded metal wire, the CM-EIFS extrapolation method is used to calculate the fatigue crack initiation life N3 and fatigue crack growth 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 fatigue crack initiation and growth life calculated by the established finite element analysis model of the corroded metal wire.

[0018] Step S2, calculating the stress distribution in the geometric model of the corroded metal wire to obtain the stress concentration area, 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] Where, σ T and ε T are true stress data and true strain data respectively;

[0025] σ nom and ε nom 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 growth 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 grows, G th <G max <G pl , the corresponding crack extension satisfies

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

[0031] S43. Solve 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 growth models, which are obtained from experiments or specifications;

[0047] E' is the elastic modulus;

[0048] K t is the stress concentration factor.

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

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

[0051] S12. The surface corrosion point cloud data of the metal wire 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 fatigue crack growth life N2 of the corroded metal wire specifically includes the following steps:

[0057] S431, embedding the damage criterion and the failure 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 approximately simulate the discontinuous field around the crack. 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 corrosion 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 growth model, the theoretical life of the numerical simulation is made close to the experimental result by adjusting the initial crack size;

[0063] S54. Estimate 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 the fatigue life of a 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 location of the pit of the corroded metal wire from the stress concentration area, and set the cross-sectional shape contour of the location of the pit of the corroded metal wire 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 growth life N2 of the corroded metal wire are obtained;

[0068] Verify the calculation module, using 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;

[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 a corroded metal wire:

[0075] This method calculates fatigue life based on both the initiation and propagation lifespans of fatigue cracks, resulting in more accurate life calculations. Specifically, materials may behave differently during the initiation and propagation phases of fatigue cracks, and considering these behaviors separately can more accurately describe these behaviors. By combining the lifespans of these two phases, this method improves the reliability of predictions and reduces the uncertainty associated with a single model or assumption.

[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 finite element software for calculation and analysis, and the operation is quick. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0079] Figure 3 This is a theoretical calculation framework diagram of fatigue life 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 package of rusted metal wire;

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

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

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

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

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

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

[0088] Figure 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] To make the objectives, technical solutions, and advantages of this specification more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the specific embodiments of this specification and the corresponding drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this invention.

[0090] The present invention proposes a method for calculating the fatigue life of corroded metal wires. This method establishes a finite element calculation model of a real corroded surface and then calculates its stress concentration area, thereby determining the location, size, and crack propagation direction of dangerous pits. Furthermore, damage evolution criteria and failure criteria are defined. 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 wires.

[0091] Fatigue experiments were conducted on rusted metal wires. 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 rusted metal wires, and 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 rusted 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, can be used repeatedly for calculation, and has strong use value. Due to the special curved surface shape of the wire, the depth assignment method cannot be directly applied to curved materials. Therefore, the accuracy and application of the 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; the present invention takes into account the initiation life of fatigue cracks when calculating the fatigue life, and can be well applied in the calculation of low-cycle fatigue or medium- and high-cycle fatigue life.

[0093] Figure 1 The following is a flow chart of the method for calculating the fatigue life of a corroded metal wire according to this embodiment. 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. The processed results are then refined to obtain the geometric model M1 of the corroded metal wire, which is then imported 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 rust on the metal wire surface multiple times and at multiple angles to obtain point cloud data of the rust on the metal wire surface. The point cloud data of the rust on the metal wire surface 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 matrix-aligned to obtain 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 use hexahedral C3D8R units for mesh division, 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 propagation 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 M3 damage criterion and failure criterion of the finite element calculation model:

[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. 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, and C4 are material constants related to the energy release rate.

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

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

[0109]

[0110] C3=C4=m / 2

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

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

[0113] The damage and failure criteria were embedded into the finite element calculation model M3 through code to perform fatigue crack initiation and propagation analysis, deriving the fatigue crack initiation and propagation life of the corroded metal wire. In the fatigue crack initiation and propagation analysis, additional terms—step expansion and crack tip expansion—were introduced to approximate the discontinuous field around the crack. The step expansion term is used to represent elements completely cut by the crack, while the crack tip expansion term is used to represent elements partially separated 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. In this way, the equivalent initial crack depth (CM-EIFS estimated value), fatigue crack initiation life N3 and propagation life N4 are estimated; the crack initiation life includes the crack nucleation life and 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 corroded metal wire model.

[0118] The specific definitions of the device for calculating the fatigue life of a corroded metal wire can be found in the definitions of the method for calculating the fatigue life of a corroded metal wire described above and will not be further elaborated here. Each module within the aforementioned device for calculating the fatigue life of a metal wire can be implemented in whole or in part via software, hardware, or a combination thereof. Each of these modules can be embedded in or independent of a processor within a computer device in hardware form, or stored in a computer device memory in software form, allowing the processor to call and execute the corresponding operations of each module.

[0119] This specification also provides the structure of the 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 calculation method for the fatigue life of corroded metal wire is provided.

[0120] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program. 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 may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory may 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 can be combined arbitrarily. In order 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 the fatigue life of a 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 location of the corrosion pit of the corroded metal wire from the stress concentration area, and setting the cross-sectional shape contour of the location of the corrosion pit 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 geometric model of the corroded metal wire 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 obtained in step S3, fatigue crack initiation and growth damage criteria and fracture criteria of the corroded metal wire are defined respectively. Finally, the criterion program is embedded in the finite element software to perform calculations to obtain the fatigue crack initiation life N1 and fatigue crack growth 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 CM-EIFS extrapolation method is used to calculate the fatigue crack initiation life N3 and fatigue crack growth 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 fatigue crack initiation and growth life calculated by the established finite element analysis model of the corroded metal wire.

2. The method for calculating the fatigue life of a corroded metal wire according to claim 1, wherein: Step S2, calculating the stress distribution in the geometric model of the corroded metal wire to obtain the stress concentration area, 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 the fatigue life of a corroded metal wire according to claim 2, wherein: 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 ) Where, σ T and ε T are true stress data and true strain data respectively; σ nom and ε nom are nominal stress data and nominal strain data respectively; In() represents a logarithmic operation.

4. The method for calculating the fatigue life of a corroded metal wire according to claim 1, wherein: Step S4 specifically includes the following sub-steps: S41. Define the damage criteria for fatigue crack initiation and growth 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 grows, G th <G max <G pl , the corresponding crack extension satisfies S42, Fatigue failure criterion of rusted metal wire: When G c ≤G max , fracture failure occurs; S43. Solve 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 the fatigue life of a corroded metal wire according to claim 4, wherein: 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 growth models, which are obtained from experiments or specifications; E' is the elastic modulus; K t is the stress concentration factor.

6. The method for calculating the fatigue life of a corroded metal wire according to claim 1, wherein: Step S1 of obtaining the surface point cloud data of the corroded metal wire comprises the following sub-steps: S11. Scan the rust on the surface of the metal wire material multiple times and at multiple angles using a non-contact surface profiler to obtain point cloud data of the rust on the surface of the metal wire material; S12. The surface corrosion point cloud data of the metal wire 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 the fatigue life of a corroded metal wire according to claim 4, wherein: The step S43 of obtaining the fatigue crack initiation life N1 and fatigue crack growth life N2 of the corroded metal wire specifically includes the following steps: S431, embedding the damage criterion and the failure 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 approximately simulate the discontinuous field around the crack. 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 the fatigue life of a corroded metal wire according to claim 1, wherein: 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 corrosion 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 growth model, the theoretical life of the numerical simulation is made close to the experimental result by adjusting the initial crack size; S54. Estimate 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 location of the pit of the corroded metal wire from the stress concentration area, and set the cross-sectional shape contour of the location of the pit of the corroded metal wire 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 growth life N2 of the corroded metal wire are obtained; Verify the calculation module, using 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; 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 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 according to any one of claims 1 to 8.

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