A method and system for flat panel filter fatigue crack growth and life prediction based on FRANC3D

Abstract

The application provides a flat-plate divertor fatigue crack propagation and life prediction method based on FRANC3D, which comprises the following steps: constructing a three-dimensional geometric model of the flat-plate divertor; performing heat transfer, structure and thermal fatigue analysis on the flat-plate divertor model by using a finite element software ANSYS to determine the most dangerous position; creating an initial crack at the most dangerous position of the model by using a three-dimensional crack propagation analysis software FRANC3D, and re-dividing the mesh around the crack tip; extracting stress intensity factors K I , K II and K III of the crack front, and determining the crack propagation direction based on the energy release rate criterion; combining a fatigue crack propagation rate model to calculate the crack propagation increment and gradually update the crack front geometry, so as to realize the simulation of the three-dimensional crack propagation path; obtaining the crack propagation history through cyclic iteration, and combining the fatigue propagation rate model to predict the fatigue life of the flat-plate divertor. The application can realize the visual analysis of the crack propagation behavior, and predict the fatigue life of the flat-plate divertor under the related loading conditions of a fusion reactor.

Description

Technical Field

[0001] This invention belongs to the field of nuclear fusion engineering and fracture mechanics technology, and relates to a method and system for fatigue crack propagation and lifetime prediction of flat plate divertors based on FRANC3D. Background Technology

[0002] Flat-plate divertors are considered one of the most promising structures for future fusion reactors due to their excellent heat dissipation performance. Currently, novel flat-plate divertors have demonstrated the ability to remove 1000 cycles of heat flux at 20 MW / m² while maintaining the materials within their allowable temperature range. However, because flat-plate divertors employ a composite of multiple materials—from the plasma-facing side: tungsten (W) and its alloys, oxygen-free copper (Cu) as the intermediate layer, copper alloys as the heat sink, and steel as the structural material—and are subjected to cyclic alternating loads during actual service, they are prone to various types of damage. Delamination at the tungsten-copper interface is one of the most serious failure modes, directly reducing divertor life and affecting the safe operation of the device. Due to the significant difference in the coefficients of thermal expansion and elastic modulus between W and Cu, stress concentration and large thermal mismatch stress occur near the interface. After repeated heating and cooling cycles, cracks easily initiate and propagate at this interface, ultimately leading to delamination, which seriously threatens the safe and stable operation of the device. Therefore, it is necessary to study the evolution of damage behavior such as crack initiation, propagation, and delamination at the tungsten-copper interface of the divertor under a high cyclic heat load of 20 MW / m2.

[0003] The initiation, propagation, and delamination of interfacial cracks can reduce the reliability and service life of divertors. Therefore, fatigue life prediction is crucial for ensuring the safe and stable operation of divertors and related equipment. There are two main categories of methods for predicting the fatigue life of divertors: one based on stress / strain-life curves (SN curves or ε-N curves) and fatigue cumulative damage theory; and the other based on fracture mechanics and crack propagation rate curves.

[0004] Methods based on stress / strain-life curves primarily rely on macroscopic stress / strain responses, lacking in-depth descriptions of microscopic damage mechanisms and struggling to accurately depict crack morphology changes and propagation paths. Furthermore, the empirical parameters in the models require extensive fatigue test data fitting, which is time-consuming and costly. Methods for predicting fatigue life based on fracture mechanics theory overcome these shortcomings. They can describe changes in crack propagation and, by analyzing the stress intensity factor at the crack tip and combining it with a crack propagation rate model, calculate the number of cycles required for the crack to expand from its initial size to its critical size, thereby predicting the fatigue life of the structure.

[0005] Therefore, visualizing the dynamic process of crack propagation in a flat plate divertor under high thermal load and understanding its fatigue crack propagation law is crucial for improving divertor reliability and optimizing its structure and manufacturing process. Secondly, accurately predicting the fatigue life of the divertor based on fracture mechanics methods allows for the development of reasonable maintenance and replacement strategies, reducing operating and maintenance costs and ensuring long-term stable operation. FRANC3D (Fracture Analysis Code 3D), a professional three-dimensional fracture mechanics analysis software, can automatically insert cracks, re-mesh, and calculate stress intensity factors, thus enabling the achievement of these objectives. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a method and system for fatigue crack propagation and life prediction of a flat divertor based on FRANC3D, which aims to solve the problem that the existing technology is difficult to accurately simulate the three-dimensional crack propagation behavior of divertors under complex loads, so as to reasonably predict its fatigue life.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for fatigue crack propagation and life prediction of a flat plate divertor based on FRANC3D, the method specifically includes the following steps: S1. Construct a three-dimensional geometric model of a flat plate divertor, the model including tungsten and its alloys, intermediate layer, copper alloy heat sink, structural materials and its internal cooling channels; S2. Use the finite element software ANSYS to perform heat transfer, structural and thermal fatigue analysis on the flat plate divertor model to obtain temperature distribution and stress-strain distribution. S3. Determine the location of crack initiation based on the analysis results; S4. Introduce an initial crack at the crack initiation location and re-mesh the local area; S5. Calculate the stress intensity factor to simulate the crack propagation behavior of a flat plate divertor. S6. Based on the fatigue propagation rate model, predict the fatigue crack propagation life of the flat plate divertor.

[0008] Furthermore, in step S1, constructing the three-dimensional geometric model of the flat plate divertor specifically includes the following steps: S11. Use 3D modeling software to establish a 3D geometric model of the flat plate divertor. Sequentially establish the plasma material potassium tungsten layer KW, the oxygen-free copper OFC intermediate layer, the oxide dispersion copper alloy ODS_Cu heat sink layer, and the structural material low activation steel CLF-1 layer. Among them, ODS_Cu and CLF-1 are connected as a composite heat sink. S12. Uniformly distributed finned internal rib structures are opened inside the composite heat sinks ODS_Cu and CLF-1 to enhance heat transfer.

[0009] Furthermore, in step S2, the heat transfer, structure, and thermal fatigue analysis of the flat plate divertor model are performed using the finite element software ANSYS, as follows: S21. Heat transfer analysis: Based on the three-dimensional geometric model of the flat plate divertor constructed in step S1, boundary conditions are set in combination with the actual operation of the divertor to obtain the temperature distribution of different materials. S22. Structural Analysis: Using the temperature results obtained from heat transfer as input, the stress and strain distributions of the divertor module are obtained. S23. Thermal fatigue analysis: During service, the divertor needs to withstand cyclic thermal loads, and the material interface is prone to thermal fatigue failure. Based on the actual operating conditions, the divertor model is subjected to multiple cycles of loading to obtain temperature change curves, stress distribution and strain distribution diagrams of different materials.

[0010] Furthermore, in step S3, the crack initiation location is determined based on the finite element analysis results, as follows: S31. The fatigue mode of the divertor is mainly low-cycle thermal fatigue, and it mainly occurs in the region where plastic strain is generated. The location of maximum strain concentration is determined based on the stress-strain analysis results. This location is the most dangerous location of the divertor, and this location basically coincides with the actual crack initiation location. S32. Determine the location of maximum strain as the crack initiation location, and determine the crack center and orientation by picking coordinates or nodes.

[0011] Furthermore, in step S4, an initial crack is inserted at the most dangerous location in the model using the three-dimensional crack propagation analysis software FRANC3D, as follows: S41. Import the overall divertor model calculated in step S3 into FRANC3D, and divide the overall model into sub-models, and re-mesh the sub-models. S42. Based on the actual fatigue crack initiation, fatigue cracks in divertors usually initiate at the edge of the tungsten-copper interface. Referring to the shape and size characteristics of the actual crack, a long, shallow surface crack is introduced at the most dangerous location through a graphical interface or coordinate input. The initial length a of the crack is 1-5 mm, the depth b is 0.5-1 mm, and the crack direction is perpendicular to the tungsten-copper interface. S43. Re-mesh the area around the crack tip in the sub-model to facilitate the calculation of the stress field at the crack tip.

[0012] Further, in step S5, the stress intensity factor is calculated. K I ,K II , K III The process involves predicting three-dimensional crack propagation based on the stress intensity factor, determining the crack propagation direction using the energy release rate criterion, calculating the crack propagation increment using the fatigue crack propagation rate formula, updating the crack front geometry, and simulating the crack propagation behavior of a flat plate divertor. The procedure is as follows: S51. Define the expansion step size and select the crack propagation rate model; S52. Export the model mesh containing cracks and submit it to ANSYS finite element software for stress calculation under fatigue load. The software will automatically read the stress analysis results. S53. The M-integral method is used to calculate the composite stress intensity factor at the crack leading edge node. By separating the integral terms, the stress intensity factor amplitude at each leading edge node is calculated independently. K I , K II , K III The relationship between the energy release rate G at the crack tip and the stress intensity factor is expressed as:

[0013] in E The elastic modulus of the material. Poisson's ratio; in the simulation, the system calculates the energy release rate in each possible propagation direction of the crack tip, and selects a value that allows... G The angle at which the maximum value is taken as the actual expansion direction of the local leading edge node; S54. Calculate the local torsion angle of each node on the crack front; S55. Calculate the local crack propagation distance at each node; S56. The extended new crack leading edge is smoothed to obtain a new crack leading edge; S57. Mesh the new crack front; S58. Calculate the stress intensity factor at the new crack front after crack propagation, and determine whether the result satisfies the propagation condition. If the condition is satisfied, i.e. If the condition is met, the crack propagation continues, updating the geometry of the crack front. If this condition is not met, then... If the crack propagation terminates, the cycle repeats until the termination condition is met; where... The stress intensity factor amplitude is the difference between the maximum and minimum stress intensity factors. = K max - K min , This is the threshold value for fatigue crack propagation in materials; S59. ANSYS reads the crack file simulated by FRANC3D and obtains the crack propagation path diagram in the global model of the divertor, thus visualizing the crack propagation process.

[0014] Furthermore, in step S6, the fatigue crack propagation life of the flat plate divertor is predicted by combining the fatigue propagation rate model, specifically including the following steps: S61. Using the multiple crack tip stress intensity factors and crack fatigue propagation size obtained in step S5, establish the correspondence between stress intensity factors and crack size. S62. Select the Paris crack propagation rate model to predict the fatigue crack propagation life of the divertor:

[0015] In the formula, The fatigue crack propagation life rate is given by C and m, which are material-dependent constants. This represents the stress intensity factor amplitude, which is the difference between the maximum and minimum stress intensity factors.

[0016] The present invention also provides a fatigue crack propagation and life prediction system for flat plate divertors based on FRANC3D, which employs the method described above.

[0017] The beneficial effects of this invention are as follows: 1) This invention realizes the three-dimensional dynamic evolution simulation of cracks in a flat plate divertor under complex thermo-mechanical coupling environment, which is closer to the real physical state than the traditional one-dimensional or two-dimensional simplified methods.

[0018] 2) The method for fatigue crack propagation and life prediction of flat plate divertors based on FRANC3D proposed in this invention can visualize the crack propagation morphology and path, providing a reliable theoretical basis for the structural optimization design and operation and maintenance strategy of divertors.

[0019] 3) This invention accurately calculates the stress intensity factor (including KI, KII, KIII) and energy release rate at the three-dimensional crack tip through the core solver of FRANC3D, laying a solid foundation for lifetime prediction based on crack propagation rate models such as Paris, and can significantly improve the reliability of the evaluation results.

[0020] In summary, this invention combines finite element analysis with FRANC3D crack propagation simulation to construct a three-dimensional fatigue crack propagation simulation and life prediction method for flat plate divertors. This method visualizes the crack propagation morphology and path, enabling reasonable prediction of the divertor's fatigue life. The proposed method has good engineering applicability and scalability, providing important technical support for the optimized design of divertor structures and the formulation of operation and maintenance strategies.

[0021] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a flowchart illustrating the overall process of the method of the present invention.

[0023] Figure 2 This is a flowchart illustrating the workflow of ANSYS combined with FRANC3D.

[0024] Figure 3 This is a schematic diagram of the flat-plate divertor module. 1. Plasma-facing material layer; 2. Intermediate oxygen-free copper layer; 3. Oxide-dispersed copper alloy layer; 4. Structural material layer; 5. Cover plate. The internal cooling channels are shown in orange boxes.

[0025] Figure 4 This is a temperature distribution diagram for fatigue analysis of a flat plate divertor.

[0026] Figure 5 This is a strain distribution diagram for fatigue analysis of a flat plate divertor. Detailed Implementation

[0027] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0029] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0030] like Figures 1-3 As shown, this embodiment of the invention provides a method for simulating fatigue crack propagation and predicting the life of a flat plate divertor, comprising the following steps: Step S1: Create a 3D model of the divertor module, referring to... Figure 3 The flat plate divertor module consists of a plasma-facing material layer 1, an intermediate layer 2, an oxide-dispersed copper alloy layer 3, a structural material layer 4, and a cover plate 5, from top to bottom. The copper alloy layer and the structural material layer together form a composite heat sink, and the interior is equipped with uniformly distributed finned channels.

[0031] Step S2: Perform steady-state heat transfer, structural and thermal fatigue analysis using ANSYS.

[0032] Specifically, the material properties of KW, Cu, ODS-Cu, and RAFM steel were defined and meshed. Boundary conditions were then set as follows: velocity inlet with a flow velocity of 12.3 m / s (flow rate of 5 t / h), inlet water temperature of 20 ℃; and pressure outlet with a relative pressure of 0 Pa and a loaded heat flux of 20 MW / m³. 2 The load is applied to one of the KW chips. After the above settings are completed, a finite element analysis is performed.

[0033] Furthermore, steady-state heat transfer analysis was performed to obtain the temperature distribution of KW, Cu, ODS-Cu, and RAFM steel materials in the divertor model, and to determine whether the conditions were met based on the allowable temperatures of different materials.

[0034] Furthermore, using the results of steady-state heat transfer analysis as input, the stress and strain distributions of KW, Cu, ODS-Cu, and RAFM steel materials in the divertor model were calculated. The stress evaluation criteria were then used to determine whether the material stress was within the allowable range. The strain distribution results showed that only the Cu layer underwent plastic deformation, with the maximum value occurring at the edge of the KW-Cu interface.

[0035] Furthermore, thermal fatigue analysis was performed. The divertor model was subjected to 10 cycles of loading to obtain the temperature change curves and maximum fatigue deformation of different divertor materials over time. Monitoring points were set at locations with large deformations, and the temperature and plastic strain at the monitoring points were extracted to calculate the cyclic equivalent plastic strain. Figure 4 This is a temperature distribution diagram for fatigue analysis of a flat plate divertor. Figure 5 This is a strain distribution diagram for fatigue analysis of a flat plate divertor.

[0036] Step S3: Determine the crack initiation location based on the analysis results. Through heat transfer, structural, and fatigue simulation analysis, determine the location of the maximum strain in the divertor. The region with the maximum strain is the most dangerous region and is most prone to fatigue cracks; this region is then determined as the initial crack location.

[0037] Specifically, the location of the maximum strain of the divertor in the finite element analysis is the edge of the tungsten-copper interface, which is determined as the initial crack location, and the crack center and orientation are determined by coordinate or node picking.

[0038] Step S4: Introduce an initial crack at the crack initiation location and re-mesh the local area.

[0039] Specifically, sub-models are first extracted from the overall divertor model, and then the mesh is re-generated on the sub-models. The sub-models are local structures that include the crack initiation locations.

[0040] Furthermore, the sub-model file is imported into the FRANC3D crack analysis software, and an initial crack with a preset shape and geometric parameters is inserted at the crack initiation location determined by S3 through the crack analysis module.

[0041] Furthermore, using FRANC3D's automatic mesh remapping function, the original mesh near the crack is deleted, generating a refined mesh containing singular elements at the crack front.

[0042] Step S5: Solve for the stress intensity factor at the crack tip to simulate the crack propagation path of the flat plate divertor.

[0043] Specifically, the new mesh model containing the crack is exported to the ANSYS finite element solver for calculation, and the software automatically reads the stress analysis results. The composite stress intensity factor at each node of the crack lead is calculated in FRANC3D using the M-integral method after post-processing. K I , K II , K III .

[0044] Furthermore, the crack propagation step size is set, and the local torsional angle and local crack propagation distance of each node on the crack lead are calculated. FRANC3D updates the crack lead geometry based on the calculated propagation amount and meshes the new crack lead. The above steps are repeated to perform multi-step crack propagation simulation. The maximum circumferential tensile stress criterion is used to determine whether the crack has propagated until the crack reaches the critical size.

[0045] Furthermore, ANSYS reads the crack file simulated by FRANC3D to obtain the crack propagation path diagram in the global model of the divertor, thus visualizing the crack propagation process.

[0046] Step S6: Combine the fatigue propagation rate model to predict the fatigue crack propagation life of the flat plate divertor.

[0047] Specifically, based on the Paris fatigue crack propagation rate formula, combined with the stress intensity factor amplitude of each propagation step... and the corresponding crack propagation increment The total number of cycles required for the crack to propagate from its initial size to its critical size is calculated, which is the fatigue crack propagation life of the flat plate divertor.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for fatigue crack propagation and life prediction of a flat plate divertor based on FRANC3D, characterized in that, The method specifically includes the following steps: S1. Construct a three-dimensional geometric model of a flat plate divertor, the model including tungsten and its alloys, intermediate layer, copper alloy heat sink, structural materials and its internal cooling channels; S2. Use the finite element software ANSYS to perform heat transfer, structural and thermal fatigue analysis on the flat plate divertor model to obtain temperature distribution and stress-strain distribution. S3. Determine the location of crack initiation based on the analysis results; S4. Introduce an initial crack at the crack initiation location and re-mesh the local area; S5. Calculate the stress intensity factor to simulate the crack propagation behavior of a flat plate divertor. S6. Based on the fatigue propagation rate model, predict the fatigue crack propagation life of the flat plate divertor.

2. The method for fatigue crack propagation and life prediction of a flat plate divertor based on FRANC3D according to claim 1, characterized in that, In step S1, constructing the three-dimensional geometric model of the flat plate divertor specifically includes the following steps: S11. Use 3D modeling software to establish a 3D geometric model of the flat plate divertor. Sequentially establish the plasma material potassium tungsten layer KW, the oxygen-free copper OFC intermediate layer, the oxide dispersion copper alloy ODS_Cu heat sink layer, and the structural material low activation steel CLF-1 layer. Among them, ODS_Cu and CLF-1 are connected as a composite heat sink. S12. Uniformly distributed finned internal rib structures are opened inside the composite heat sinks ODS_Cu and CLF-1 to enhance heat transfer.

3. The method for fatigue crack propagation and life prediction of a flat plate divertor based on FRANC3D according to claim 2, characterized in that, In step S2, the heat transfer, structure, and thermal fatigue analysis of the flat plate divertor model are performed using the finite element software ANSYS. The process is as follows: S21. Heat transfer analysis: Based on the three-dimensional geometric model of the flat plate divertor constructed in step S1, boundary conditions are set in combination with the actual operation of the divertor to obtain the temperature distribution of different materials. S22. Structural Analysis: Using the temperature results obtained from heat transfer as input, the stress and strain distributions of the divertor module are obtained. S23. Thermal fatigue analysis: During service, the divertor needs to withstand cyclic thermal loads, and the material interface is prone to thermal fatigue failure. Based on the actual operating conditions, the divertor model is subjected to multiple cycles of loading to obtain temperature change curves, stress distribution and strain distribution diagrams of different materials.

4. The method for fatigue crack propagation and life prediction of a flat plate divertor based on FRANC3D according to claim 3, characterized in that, In step S3, the crack initiation location is determined based on the finite element analysis results, as follows: S31. The fatigue mode of the divertor is mainly low-cycle thermal fatigue, and it mainly occurs in the region where plastic strain is generated. The location of maximum strain concentration is determined based on the stress-strain analysis results. This location is the most dangerous location of the divertor, and this location basically coincides with the actual crack initiation location. S32. Determine the location of maximum strain as the crack initiation location, and determine the crack center and orientation by picking coordinates or nodes.

5. The method for fatigue crack propagation and life prediction of a flat plate divertor based on FRANC3D according to claim 4, characterized in that, In step S4, an initial crack is inserted at the most dangerous location on the model using the three-dimensional crack propagation analysis software FRANC3D. The process is as follows: S41. Import the overall divertor model calculated in step S3 into FRANC3D, and divide the overall model into sub-models, and re-mesh the sub-models. S42. Based on the actual fatigue crack initiation, fatigue cracks in divertors usually initiate at the edge of the tungsten-copper interface. Referring to the shape and size characteristics of the actual crack, a long, shallow surface crack is introduced at the most dangerous location through a graphical interface or coordinate input. The initial length a of the crack is 1-5 mm, the depth b is 0.5-1 mm, and the crack direction is perpendicular to the tungsten-copper interface. S43. Re-mesh the area around the crack tip in the sub-model to facilitate the calculation of the stress field at the crack tip.

6. The method for fatigue crack propagation and life prediction of a flat plate divertor based on FRANC3D according to claim 5, characterized in that, In step S5, the stress intensity factor is calculated. K I , K II , K III The process involves predicting three-dimensional crack propagation based on the stress intensity factor, determining the crack propagation direction using the energy release rate criterion, calculating the crack propagation increment using the fatigue crack propagation rate formula, updating the crack front geometry, and simulating the crack propagation behavior of a flat plate divertor. The procedure is as follows: S51. Define the expansion step size and select the crack propagation rate model; S52. Export the model mesh containing cracks and submit it to ANSYS finite element software for stress calculation under fatigue load. The software will automatically read the stress analysis results. S53. The M-integral method is used to calculate the composite stress intensity factor at the crack leading edge node. By separating the integral terms, the stress intensity factor amplitude at each leading edge node is calculated independently. K I , K II , K III The relationship between the energy release rate G at the crack tip and the stress intensity factor is expressed as: in E The elastic modulus of the material. Poisson's ratio; in the simulation, the system calculates the energy release rate in each possible propagation direction of the crack tip, and selects a value that allows... G The angle at which the maximum value is taken as the actual expansion direction of the local leading edge node; S54. Calculate the local torsion angle of each node on the crack front; S55. Calculate the local crack propagation distance at each node; S56. The extended new crack leading edge is smoothed to obtain a new crack leading edge; S57. Mesh the new crack front; S58. Calculate the stress intensity factor at the new crack front after crack propagation, and determine whether the result satisfies the propagation condition. If the condition is satisfied, i.e. If the condition is met, the crack propagation continues, updating the geometry of the crack front. If this condition is not met, then... If the crack propagation terminates, the cycle repeats until the termination condition is met; where... The stress intensity factor amplitude is the difference between the maximum and minimum stress intensity factors. = K max - K min , This is the threshold value for fatigue crack propagation in materials; S59. ANSYS reads the crack file simulated by FRANC3D and obtains the crack propagation path diagram in the global model of the divertor, thus visualizing the crack propagation process.

7. The method for fatigue crack propagation and life prediction of a flat plate divertor based on FRANC3D according to claim 6, characterized in that, In step S6, the fatigue crack propagation life of the flat plate divertor is predicted by combining the fatigue propagation rate model, specifically including the following steps: S61. Using the multiple crack tip stress intensity factors and crack fatigue propagation size obtained in step S5, establish the correspondence between stress intensity factors and crack size. S62. Select the Paris crack propagation rate model to predict the fatigue crack propagation life of the divertor: In the formula, The fatigue crack propagation life rate is given by C and m, which are material-dependent constants. This represents the stress intensity factor amplitude, which is the difference between the maximum and minimum stress intensity factors.

8. A fatigue crack propagation and life prediction system for flat plate divertors based on FRANC3D, characterized in that, The system employs the method as described in any one of claims 1 to 7.

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