Numerical simulation method and system for failure process of water turbine blade based on fracture mechanics

Abstract

The application discloses a kind of numerical simulation method and system based on fracture mechanics of water turbine blade failure process, comprising: introducing initial crack defect in blade three-dimensional geometric model;Based on the blade three-dimensional geometric model, the joint simulation of hydrodynamics and structural mechanics is carried out to the blade, and the stress and strain distribution of crack tip region is obtained;From the stress and strain distribution of crack tip region, the key parameters of crack tip are extracted;Using the key parameters of crack tip, according to crack propagation criterion, the crack propagation rate and propagation path are determined;In the process of crack propagation, the grid is dynamically encrypted and reconstructed, the crack front position is updated, until the crack reaches critical condition, and the failure life prediction result of blade is output, the method and system can not only predict crack propagation rate and path, but also determine the critical life of blade, realize the whole process simulation of crack from initiation, expansion to final fracture.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic machinery and hydropower engineering technology, and relates to a numerical simulation method and system for the failure process of turbine blades based on fracture mechanics. Background Technology

[0002] As a critical load-bearing component of the turbine unit, turbine blades endure a variety of complex forces during long-term operation, including water pressure pulsation, sand impact, cavitation collapse, and start-up and shutdown loads. These external loads often lead to cracks on or inside the blade surface. Once formed, these cracks gradually propagate under cyclic loading, eventually causing blade fracture failure. Blade fracture not only causes unplanned shutdowns of the unit but can also lead to serious safety accidents and huge economic losses. Therefore, studying the entire process of blade crack initiation, propagation, and failure is of great significance for the safe operation and life management of the turbine unit.

[0003] In existing technologies, some scholars use the finite element method to calculate the stress distribution at the crack tip of a blade to assess the crack propagation trend; others use fracture mechanics formulas to estimate the crack growth rate or remaining life. However, most of these methods are limited to static analysis or calculations under single stress conditions, and cannot fully consider the actual crack propagation path in complex fluid-structure interaction environments. Furthermore, traditional methods typically assume a fixed crack propagation direction, which is insufficient to reflect the nonlinear behavior of cracks changing direction, bifurcation, or merging in complex stress fields, leading to discrepancies between life prediction results and actual conditions.

[0004] Furthermore, traditional fracture analysis methods have two shortcomings in engineering applications: first, they lack a dynamic mesh update mechanism, making it impossible to realize the continuous evolution of the geometric model and computational domain during crack propagation; second, the lifetime prediction results often only provide a single cycle lifetime estimate, lacking quantitative simulation of the entire crack propagation process and comparative analysis under multiple working conditions. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a numerical simulation method and system for the failure process of turbine blades based on fracture mechanics. This method and system can not only predict the crack propagation rate and path, but also determine the critical life of the blade, realizing the simulation of the entire process of crack initiation, propagation and final fracture.

[0006] To achieve the above objectives, this invention discloses a numerical simulation method for the failure process of a hydraulic turbine blade based on fracture mechanics, comprising: Initial crack defects are introduced into the three-dimensional geometric model of the blade; Based on the three-dimensional geometric model of the blade, under the fluid-structure interaction framework, the blade is subjected to joint simulation of hydrodynamics and structural mechanics to obtain the stress and strain distribution in the crack tip region. Based on the principles of fracture mechanics, key parameters of the crack tip are extracted from the stress and strain distribution in the crack tip region. Using the key parameters at the crack tip, the crack propagation rate and propagation path are determined according to the crack propagation criteria. During crack propagation, the mesh is dynamically refined and reconstructed to update the position of the crack front until the crack reaches the critical condition, and the failure life prediction result of the blade is output.

[0007] Furthermore, the initial crack includes at least a surface crack, a buried crack, or a through crack, and the shape of the initial crack includes at least a semi-elliptical, linear, or irregular shape.

[0008] Furthermore, the key parameters at the crack tip include stress intensity factor, strain energy release rate, and stress field directionality index.

[0009] Furthermore, the crack propagation direction is determined by using the maximum circumferential stress criterion and / or the maximum energy release rate criterion.

[0010] Furthermore, when the crack length a extends to the critical length a c When this happens, the blade is considered to have reached a failure state; When the stress intensity factor K I Exceeding the material's fracture toughness K IC If the blade breaks, it is considered to have reached a failure state.

[0011] Furthermore, the process of dynamically refining and reconstructing the mesh during crack propagation is as follows: Locally refine the mesh in the crack leading edge region; After the crack propagates, the local mesh is reconstructed using node interpolation or mapping methods.

[0012] Furthermore, the failure life prediction results include at least the crack length variation curve with operating time or number of cycles, the crack propagation rate variation with external load amplitude, the correspondence between critical crack conditions and life threshold, and the correlation results between overall efficiency reduction and crack propagation degree.

[0013] This invention discloses a numerical simulation system for the failure process of a hydro turbine blade based on fracture mechanics, comprising: An import module is used to introduce initial crack defects into the three-dimensional geometric model of the blade; The simulation module is used to perform joint simulation of hydrodynamics and structural mechanics of the blade based on the three-dimensional geometric model of the blade in a fluid-structure interaction framework, and to obtain the stress and strain distribution in the crack tip region. The extraction module is used to extract key parameters of the crack tip from the stress and strain distribution in the crack tip region based on the principles of fracture mechanics. The determination module is used to determine the crack propagation rate and propagation path by utilizing the key parameters at the crack tip and based on crack propagation criteria. The output module is used to dynamically refine and reconstruct the mesh during crack propagation, update the position of the crack front, and output the blade failure life prediction results until the crack reaches the critical condition.

[0014] This invention discloses a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the numerical simulation method for the failure process of a turbine blade based on fracture mechanics.

[0015] This invention discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the numerical simulation method for the failure process of a turbine blade based on fracture mechanics.

[0016] The present invention has the following beneficial effects: The numerical simulation method and system for the failure process of turbine blades based on fracture mechanics, as described in this invention, introduces crack defects into the three-dimensional model of the blade and combines fluid-structure interaction simulation, fracture mechanics parameter calculation, crack propagation criteria, and dynamic mesh updates to simulate the entire process of turbine blade failure, from crack initiation to final fracture. Compared with existing methods that only rely on static evaluation or a single criterion, this invention can more realistically reflect the dynamic laws of crack evolution, predict crack propagation rate and path, and accurately determine the failure moment by combining critical length and fracture toughness as dual criteria. It also supports life prediction and maintenance cycle optimization, possessing higher accuracy and reliability, and has significant engineering application value. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a graph showing the change in crack length over operating time. Figure 3 The graph shows the variation of crack propagation rate with operating time. Figure 4 The graph shows the decrease in unit efficiency as crack propagation progresses. Figure 5 This is a schematic diagram of the lifespan consumption curve and the failure judgment threshold. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0021] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0022] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0023] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0024] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0027] Example 1 refer to Figure 1 The numerical simulation method for the failure process of a turbine blade based on fracture mechanics, as described in this invention, includes the following steps: 1) Introduce initial crack defects into the three-dimensional geometric model of the blade. The initial cracks include at least surface cracks, buried cracks, or through cracks. The shape of the cracks includes at least semi-elliptical, linear, or irregular shapes. The initial morphology of the crack defect can be set based on actual monitoring data or assumed operating conditions, including crack length a, depth d, tilt angle θ, and location, in order to simulate the impact of different types of defects on the blade failure process.

[0028] 2) Based on the three-dimensional geometric model of the blade, under the fluid-structure interaction framework, the blade is subjected to joint simulation of hydrodynamics and structural mechanics to obtain the stress and strain distribution in the crack tip region; Using a coupled computational fluid dynamics (CFD) and finite element method (FEM) calculation, the fluid domain satisfies the incompressible Navier–Stokes equations, i.e.:

[0029] The structural domain satisfies the finite element equilibrium equations, namely:

[0030] Where K is the structural stiffness matrix, {u} is the displacement vector, and {F} is the fluid load vector. The fluid-structure interaction result provides the local stress distribution field at the crack tip.

[0031] 3) Based on the principles of fracture mechanics, extract key parameters of the crack tip from the stress and strain distribution in the crack tip region, including stress intensity factor, strain energy release rate and stress field directionality index. Specifically, this invention obtains the stress distribution field at the crack tip using numerical methods and determines the stress intensity factor by combining it with a geometric correction coefficient; at the same time, it calculates the strain energy release rate at the crack tip to characterize the possibility of further crack propagation.

[0032] The stress intensity factor (SIF) is used to characterize the stress field intensity at the crack tip, and commonly used modes include Mode I (opening type), Mode II (slipping type), and Mode III (tearing type).

[0033] Strain energy release rate (G): Used to represent the energy required per unit area of ​​crack to propagate.

[0034] Equivalent fracture parameters: The comprehensive crack propagation driving force is obtained through multi-mode combined calculation.

[0035] 4) Using the key parameters at the crack tip, determine the crack propagation rate and propagation path according to the crack propagation criteria; Specifically, the determination of the crack propagation rate is based on the law of fatigue crack propagation, which can reflect the trend of crack growth over time or number of operating cycles under cyclic loading or variable amplitude loading, and supports the simulation of high-cycle fatigue and low-cycle fatigue conditions.

[0036] The crack propagation direction is determined by fracture mechanics criteria, preferably the maximum circumferential stress criterion, to obtain the true propagation path of the crack in a complex stress field and to automatically identify nonlinear propagation behaviors such as crack turning, bifurcation, or merging.

[0037] The crack growth is described using fatigue crack propagation laws, typically represented by Paris's law, which states:

[0038] in, Let be the crack growth rate, ΔK be the stress intensity factor range, and C and m be material constants. For variable amplitude loading conditions, a modified Forman model can be used.

[0039] Specifically, the crack propagation direction is determined by fracture mechanics criteria: Maximum circumferential stress criterion: The crack propagates along the direction of maximum circumferential stress; Maximum energy release rate criterion: Cracks propagate along the direction of maximum energy release rate; Hybrid mode criterion: Determine the true crack propagation path under the combined effect of modes I and II.

[0040] 5) Dynamically refine and reconstruct the mesh during crack propagation, update the crack front position until the crack reaches the critical condition, and output the blade failure life prediction result.

[0041] The failure criteria for blades include one or a combination of the following two conditions: 51) When the crack length a extends to the critical length a c When this happens, the blade is considered to have reached a failure state; 52) When the stress intensity factor K I Exceeding the material's fracture toughness K IC If the blade breaks, it is determined that the blade has broken.

[0042] If any of the above conditions are met, the blade is determined to have reached a failure state.

[0043] In addition, the crack propagation process employs dynamic mesh reconstruction technology, which includes the following steps: Locally refine the mesh in the crack leading edge region to improve computational accuracy; After crack propagation, the local mesh is reconstructed using nodal interpolation or mapping methods; To ensure the continuity of the crack trajectory and the convergence of the calculation process, the evolution of the crack is accurately reflected.

[0044] Lifespan prediction results include the following: 1a) Curve of crack length variation with operating time or number of cycles; 2a) Law of crack propagation rate variation with external load amplitude; 3a) Correspondence between critical crack condition and life threshold; 4a) Correlation between overall efficiency reduction and crack propagation degree.

[0045] Example 2 Taking a 40MW bulb turbine unit as the research object, this invention is used to simulate and analyze the crack propagation and life consumption of the blades during long-term operation.

[0046] An initial crack was created near the root of the blade leading edge, with a length of 10 mm, a depth of 3 mm, and an inclination angle of 30°. The material used was ZG0Cr13Ni5Mo stainless steel, with a fracture toughness of approximately 85 MPa·m^0.5, and the fatigue constant was obtained from experimental data. Through 3D modeling and mesh generation, local refinement was applied to the crack region to ensure that the stress gradient at the crack tip could be accurately captured.

[0047] Using a fluid-structure interaction (FSI) computational framework, unsteady solutions were performed under rated flow conditions of 160 m³ / s and rotational speed of 72 rpm to extract the fluid load on the blade surface and apply it to the structural domain. Numerical calculations show that the stress field at the crack tip exhibits a distinct opening-type characteristic, corresponding to the fracture mode dominated by Mode I; simultaneously, it is accompanied by a certain slip component, belonging to a mixed-mode crack. In each load cycle, the stress intensity factor range and energy release rate at the crack tip were obtained through fracture mechanics analysis, providing input for subsequent calculations of crack propagation behavior.

[0048] The crack propagation direction is determined based on the Paris fatigue crack propagation model and the maximum circumferential stress criterion. Numerical results show that: Early stage (0-2 years): The crack propagation rate is low, and the crack length grows slowly, basically remaining below 12 mm; Mid-term stage (2-4 years): Due to the cumulative cyclic load, the stress intensity factor at the crack tip gradually increases, and the crack length accelerates to about 20 mm. Late stage (4-6 years): The crack enters an unstable propagation stage, the propagation rate increases rapidly, and finally the crack length reaches the critical threshold of 35 mm in about the 6th year, and the blade enters the failure state.

[0049] By coupling with fluid dynamics calculations, the impact of crack propagation on unit efficiency can be obtained. For example... Figure 3 As shown, as the cracks gradually expand, the unit's efficiency continuously declines: after 5 years of operation, the efficiency drops by about 4%, reaching the set maintenance threshold; if it continues to operate into the 6th year, the efficiency drops by more than 5%, which has a serious impact on both economy and safety.

[0050] The Miner cumulative damage model is used to calculate lifetime loss, such as... Figure 4 As shown, the lifetime consumption D gradually increases over time, reaching the failure threshold D=1 in the 6th year, which is highly consistent with the critical state of crack propagation, verifying the reliability of the method.

[0051] The output results show: Figure 2 The curve showing the change in crack length over time indicates that the crack grows slowly in the early stage, accelerates its propagation after the fourth year, and finally reaches the critical length of 35 mm in the sixth year.

[0052] Figure 3 The data shows the change in crack propagation rate over time: the crack propagation rate increases significantly after the third year, entering an accelerated propagation stage, which is a high-risk area that needs to be closely monitored during operation.

[0053] Figure 4 The curve showing the decrease in unit efficiency as crack propagation indicates the impact of crack development on hydrodynamic performance, showing a clear correlation between efficiency decline and crack propagation.

[0054] Figure 5 The curve shows the lifespan consumption curve and failure determination: It displays the linear relationship between lifespan consumption and time. The failure threshold D=1 is reached after 6 years, and the corresponding crack reaches the critical condition.

[0055] This embodiment demonstrates that the present invention can not only quantitatively predict crack length and propagation rate, but also establish a correlation model between efficiency decay and lifespan consumption, realizing the simulation of the entire crack failure process. The present invention can provide operators with quantitative basis for maintenance cycles and failure early warning, avoiding sudden downtime and economic losses caused by uncontrolled crack propagation, and has significant engineering application value.

[0056] Compared with the prior art, the present invention has the following advantages and effects: This invention introduces crack defects into the three-dimensional model of a turbine blade and combines fluid-structure interaction simulation, fracture mechanics parameter calculation, crack propagation criteria, and dynamic mesh updates to simulate the entire process of a turbine blade from crack initiation to final fracture. Compared with existing methods that only rely on static evaluation or a single criterion, this invention can more realistically reflect the dynamic laws of crack evolution, predict crack propagation rate and path, and accurately determine the failure time by combining critical length and fracture toughness as dual criteria. It also supports life prediction and maintenance cycle optimization, possessing higher accuracy and reliability, and has significant engineering application value.

[0057] Example 3 The numerical simulation system for turbine blade failure process based on fracture mechanics described in this invention includes: An import module is used to introduce initial crack defects into the three-dimensional geometric model of the blade; The simulation module is used to perform joint simulation of hydrodynamics and structural mechanics of the blade based on the three-dimensional geometric model of the blade in a fluid-structure interaction framework, and to obtain the stress and strain distribution in the crack tip region. The extraction module is used to extract key parameters of the crack tip from the stress and strain distribution in the crack tip region based on the principles of fracture mechanics. The determination module is used to determine the crack propagation rate and propagation path by utilizing the key parameters at the crack tip and based on crack propagation criteria. The output module is used to dynamically refine and reconstruct the mesh during crack propagation, update the position of the crack front, and output the blade failure life prediction results until the crack reaches the critical condition.

[0058] The module division in this embodiment is illustrative and represents only one logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional modules in each embodiment of this application can be integrated into a single processor, exist as separate physical entities, or be integrated into a single module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0059] Example 4 A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the numerical simulation method for the failure process of a hydro-turbine blade based on fracture mechanics. For example, the steps include: introducing an initial crack defect into a three-dimensional geometric model of the blade; performing a joint simulation of hydrodynamics and structural mechanics on the blade within a fluid-structure interaction framework based on the three-dimensional geometric model to obtain the stress and strain distribution in the crack tip region; extracting key parameters of the crack tip from the stress and strain distribution in the crack tip region based on fracture mechanics principles; using the key parameters of the crack tip, determining the crack propagation rate and propagation path according to crack propagation criteria; dynamically refining and reconstructing the mesh during crack propagation, updating the crack front position until the crack reaches a critical condition, and outputting the blade's failure life prediction result. The memory may include main memory, such as high-speed random access memory (RAM), or non-volatile memory, such as at least one disk storage device. The processor, network interface, and memory are interconnected via an internal bus, which may be an industry-standard architecture bus, a peripheral component interconnection standard bus, or an extended industry-standard architecture bus. The bus can be categorized as an address bus, data bus, or control bus. The memory stores programs; specifically, the program may include program code, which includes computer operation instructions. The memory may include main memory and non-volatile memory, and provides instructions and data to the processor.

[0060] Example 5 A computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of a numerical simulation method for the failure process of a hydro-turbine blade based on fracture mechanics. For example, the steps include: introducing an initial crack defect into a three-dimensional geometric model of the blade; performing a joint simulation of hydrodynamics and structural mechanics of the blade within a fluid-structure interaction framework based on the three-dimensional geometric model to obtain the stress and strain distribution in the crack tip region; extracting key parameters of the crack tip from the stress and strain distribution in the crack tip region based on fracture mechanics principles; using the key parameters of the crack tip, determining the crack propagation rate and propagation path according to crack propagation criteria; dynamically refining and reconstructing the mesh during crack propagation, updating the crack front position until the crack reaches a critical condition, and outputting the blade's failure life prediction result. Specifically, the computer-readable storage medium includes, but is not limited to, volatile memory and / or non-volatile memory. The volatile memory may include random access memory (RAM) and / or cache memory, etc. The non-volatile memory may include read-only memory (ROM), hard disk, flash memory, optical disk, magnetic disk, etc.

[0061] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0062] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0063] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a processFigure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0064] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0065] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0066] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0067] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A numerical simulation method for the failure process of a hydraulic turbine blade based on fracture mechanics, characterized in that, include: Initial crack defects are introduced into the three-dimensional geometric model of the blade; Based on the three-dimensional geometric model of the blade, under the fluid-structure interaction framework, the blade is subjected to joint simulation of hydrodynamics and structural mechanics to obtain the stress and strain distribution in the crack tip region. Based on the principles of fracture mechanics, key parameters of the crack tip are extracted from the stress and strain distribution in the crack tip region. Using the key parameters at the crack tip, the crack propagation rate and propagation path are determined according to the crack propagation criteria. During crack propagation, the mesh is dynamically refined and reconstructed to update the position of the crack front until the crack reaches the critical condition, and the failure life prediction result of the blade is output.

2. The numerical simulation method for turbine blade failure process based on fracture mechanics according to claim 1, characterized in that, The initial crack includes at least a surface crack, a buried crack, or a through crack, and the shape of the initial crack includes at least a semi-elliptical, linear, or irregular shape.

3. The numerical simulation method for the failure process of a turbine blade based on fracture mechanics according to claim 1, characterized in that, The key parameters at the crack tip include stress intensity factor, strain energy release rate, and stress field directionality index.

4. The numerical simulation method for the failure process of a turbine blade based on fracture mechanics according to claim 1, characterized in that, The crack propagation direction is determined by using the maximum circumferential stress criterion and / or the maximum energy release rate criterion.

5. The numerical simulation method for the failure process of a turbine blade based on fracture mechanics according to claim 1, characterized in that, When the crack length a extends to the critical length a c When this happens, the blade is considered to have reached a failure state; When the stress intensity factor K I Exceeding the material's fracture toughness K IC If the blade breaks, it is considered to have reached a failure state.

6. The numerical simulation method for the failure process of a turbine blade based on fracture mechanics according to claim 1, characterized in that, The process of dynamically refining and reconstructing the mesh during crack propagation is as follows: Locally refine the mesh in the crack leading edge region; After the crack propagates, the local mesh is reconstructed using node interpolation or mapping methods.

7. The numerical simulation method for the failure process of a turbine blade based on fracture mechanics according to claim 1, characterized in that, The failure life prediction results include at least the crack length variation curve with operating time or number of cycles, the crack propagation rate variation with external load amplitude, the correspondence between critical crack conditions and life threshold, and the correlation between overall efficiency reduction and crack propagation degree.

8. A numerical simulation system for the failure process of a hydraulic turbine blade based on fracture mechanics, characterized in that, include: An import module is used to introduce initial crack defects into the three-dimensional geometric model of the blade; The simulation module is used to perform joint simulation of hydrodynamics and structural mechanics of the blade based on the three-dimensional geometric model of the blade in a fluid-structure interaction framework, and to obtain the stress and strain distribution in the crack tip region. The extraction module is used to extract key parameters of the crack tip from the stress and strain distribution in the crack tip region based on the principles of fracture mechanics. The determination module is used to determine the crack propagation rate and propagation path by utilizing the key parameters at the crack tip and based on crack propagation criteria. The output module is used to dynamically refine and reconstruct the mesh during crack propagation, update the position of the crack front, and output the blade failure life prediction results until the crack reaches the critical condition.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the numerical simulation method for the failure process of a turbine blade based on fracture mechanics as described in any one of claims 1-7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the numerical simulation method for the failure process of a turbine blade based on fracture mechanics as described in any one of claims 1-7.

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