Fan blade structure damage analysis method and device based on submodel

Abstract

The invention discloses a fan blade structure damage analysis method and device based on a sub-model, and is used for solving the technical problem that the existing fan blade structure damage and sub-model analysis efficiency is relatively low. The method comprises the following steps: constructing a fan blade finite element model according to obtained fan blade design parameters; performing stress calculation on the fan blade finite element model, and determining a fluid load and a Mises stress value at the Gaussian integral point of each blade unit in the fan blade finite element model at the current time; according to the fluid load, the comparison result between the Mises stress value at the Gaussian integral point of each blade unit at the current time and a preset stress threshold value and the fan blade finite element model, dynamic construction of a target fine mesh entity unit sub-model is completed; and combining a phase field model and a Lagrange-cohesion model to perform structural damage analysis on the target fine grid entity unit sub-model to generate a structural damage analysis result of the target fan blade.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a sub-model-based method and device for analyzing wind turbine blade structural damage. Background Art

[0002] Wind power generation, as a clean, renewable energy technology, has been favored by countries around the world. As a key component of wind turbines, blades, due to their complex aerodynamic effects and inherent elasticity, trigger significant fluid-structure interaction during operation. This makes blades susceptible to structural damage such as fiber breakage, matrix cracking, and adhesive debonding, thus affecting the efficiency and safety of the wind turbine.

[0003] With the rapid development of wind power technology, the size and complexity of wind turbine blades are also increasing. Larger wind turbine blades are more susceptible to wind forces in strong winds, such as typhoons, and structural damage is becoming increasingly prominent. Damage to wind turbine blades not only affects power generation efficiency but can also cause turbine failure or even collapse, resulting in significant economic losses and safety hazards. Therefore, in-depth research on structural damage in wind turbine blades is necessary to provide theoretical support for structural optimization and performance improvement.

[0004] Existing wind blade structural damage analysis methods mainly focus on the fatigue behavior of blades, and the sub-models used by most research institutes are constructed based on the entire phenomenon time range. Even at low stress levels, a complete calculation process is still required, which takes a lot of time and results in low efficiency of wind blade structural damage and sub-model analysis. Summary of the Invention

[0005] The present invention provides a sub-model-based method and device for analyzing fan blade structure damage, which are used to solve the technical problems of low efficiency of existing fan blade structure damage and sub-model analysis.

[0006] A first aspect of the present invention provides a sub-model-based wind turbine blade structural damage analysis method, comprising:

[0007] Acquiring fan blade design parameters, and constructing a fan blade finite element model based on the fan blade design parameters;

[0008] Based on a preset fluid load calculation method, a stress calculation is performed on the finite element model of the wind turbine blade to determine the fluid load and the Mises stress values ​​at the current time at the Gaussian integration points of multiple blade elements in the finite element model of the wind turbine blade;

[0009] Constructing a target fine-grid entity unit sub-model according to the fluid load, a comparison result between the Mises stress value at the Gaussian integration point of each blade unit at the current time and a preset stress threshold, and the wind turbine blade finite element model;

[0010] The phase field model and the Lagrangian-cohesion model are used to perform structural damage analysis on the target fine-grid entity element sub-model to generate a target wind turbine blade structural damage analysis result.

[0011] Optionally, constructing a finite element model of a wind turbine blade according to the wind turbine blade design parameters includes:

[0012] Determining the coordinates of discrete points of a plurality of blade airfoils' cross sections based on the fan blade design parameters;

[0013] Determining cross-sectional curves of a plurality of blade airfoils according to the coordinates of the cross-sectional discrete points of the plurality of blade airfoils;

[0014] translating and rotating the cross-sectional curves of the plurality of blade airfoils, and outputting a plurality of adjusted cross-sectional curves of the blade airfoils;

[0015] Constructing a CAD model of a wind turbine blade according to the cross-sectional curves of the plurality of adjusted blade airfoils;

[0016] Meshing the fan blade CAD model to determine the meshed fan blade CAD model;

[0017] Composite material layers are laid on the meshed wind turbine blade CAD model to output a finite element model of the wind turbine blade.

[0018] Optionally, the preset fluid load calculation method includes an empirical formula and a fluid-solid coupling calculation method; performing stress calculation on the wind turbine blade finite element model based on the preset fluid load calculation method to determine the fluid load and the Mises stress values ​​at the current time at Gaussian integration points of multiple blade units in the wind turbine blade finite element model includes:

[0019] Performing fluid load calculation on the fan blade finite element model based on an empirical formula or a fluid-solid coupling calculation method to determine the fluid load;

[0020] The fluid load is applied to the wind turbine blade finite element model and an explicit finite element analysis is performed to determine the Mises stress values ​​at the current time at the Gaussian integration points of multiple blade units in the wind turbine blade finite element model.

[0021] Optionally, constructing a target fine-grid solid element sub-model according to the fluid load, a comparison result between the Mises stress value at the current time at the Gaussian integration point of each blade element and a preset stress threshold, and the wind turbine blade finite element model includes:

[0022] Comparing the Mises stress value at the Gaussian integration point of each blade element at the current time with a preset stress threshold;

[0023] The blade unit corresponding to the Mises stress value at the current time at any Gaussian integral point that is greater than or equal to the preset stress threshold is used as a marking unit;

[0024] Based on the airfoil section where the marked unit is located, the coarse-mesh shell unit in the wind turbine blade finite element model is converted into a fine-mesh solid unit to generate an initial fine-mesh solid unit sub-model;

[0025] The displacement of the wind turbine blade finite element model is used as the boundary condition of the initial fine-mesh entity unit sub-model, the fluid load is applied as the external load on the surface of the initial fine-mesh entity unit sub-model, the stress value at the current time at the Gaussian integration point in the area corresponding to the initial fine-mesh entity unit sub-model is transferred to the initial fine-mesh entity unit sub-model based on linear interpolation, and composite material layup is performed on the initial fine-mesh entity unit sub-model to generate a target fine-mesh entity unit sub-model.

[0026] Optionally, a phase field model and a Lagrangian-cohesion model are used to perform structural damage analysis on the target fine grid entity unit sub-model to generate target wind turbine blade structural damage analysis results, including:

[0027] Using a phase field model to simulate intra-layer damage on the target fine-grid entity unit sub-model, and outputting the intra-layer damage simulation results;

[0028] Using a Lagrangian-cohesive force model to simulate interlaminar damage on the target fine-grid entity element sub-model, and generating interlaminar damage simulation results;

[0029] Based on the coupling effect of the intra-layer damage simulation results and the inter-layer damage simulation results, performing a wind blade structural damage analysis on the target fine-grid entity element sub-model, generating an initial wind blade structural simulation refinement analysis result, and recording the current time in real time;

[0030] Determine whether the current time reaches the preset phenomenon time;

[0031] If so, the refined analysis result of the initial fan blade structure simulation is used as the target fan blade structure damage analysis result.

[0032] Optionally, it also includes:

[0033] If the current time does not reach the preset phenomenon time, the finite element model of the wind turbine blade is updated based on the stress value of the Gaussian integral point of each blade unit at the current time, the displacement, velocity and acceleration of the finite element node corresponding to each blade unit, and a new finite element model of the wind turbine blade is determined;

[0034] Jumping to the step of performing stress calculation on the wind turbine blade finite element model based on the preset fluid load calculation method, and determining the Mises stress values ​​at the current time at the Gaussian integration points of multiple blade elements in the wind turbine blade finite element model, until the current time reaches the preset phenomenon time;

[0035] The initial fan blade structure simulation refinement analysis result determined when the current time reaches the preset phenomenon time is used as the target fan blade structure damage analysis result.

[0036] A second aspect of the present invention provides a sub-model-based wind turbine blade structural damage analysis device, comprising:

[0037] An acquisition module is used to acquire design parameters of the fan blades and construct a finite element model of the fan blades according to the design parameters of the fan blades;

[0038] a stress output module, configured to perform stress calculation on the wind turbine blade finite element model based on a preset fluid load calculation method, and determine the fluid load and the Mises stress values ​​at the current time at Gaussian integration points of a plurality of blade elements in the wind turbine blade finite element model;

[0039] a sub-model construction module, configured to construct a target fine-grid entity unit sub-model based on the fluid load, a comparison result between the Mises stress value at the Gaussian integration point of each blade unit at the current time and a preset stress threshold, and the wind turbine blade finite element model;

[0040] The analysis module is used to perform structural damage analysis on the target fine grid entity unit sub-model using a phase field model and a Lagrangian-cohesion model to generate a target wind turbine blade structural damage analysis result.

[0041] A third aspect of the present invention provides a computer device comprising a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the processor executes the steps of the sub-model-based wind blade structural damage analysis method as described in any one of the above items.

[0042] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements the steps of the wind turbine blade structural damage analysis method based on the sub-model as described in any one of the above.

[0043] A fifth aspect of the present invention provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, and the computer program includes program instructions, wherein when the program instructions are executed by a computer, the computer executes the steps of the sub-model-based wind blade structural damage analysis method as described in any one of the above items.

[0044] It can be seen from the above technical solutions that the present invention has the following advantages:

[0045] The above technical solution of the present invention provides a wind turbine blade structural damage analysis method based on a sub-model. First, the wind turbine blade design parameters are obtained, and a wind turbine blade finite element model is constructed according to the wind turbine blade design parameters. Then, based on a preset fluid load calculation method, a stress calculation is performed on the wind turbine blade finite element model to determine the fluid load and the Mises stress value at the current time at the Gaussian integration point of multiple blade units in the wind turbine blade finite element model. According to the comparison results between the fluid load, the Mises stress value at the current time at the Gaussian integration point of each blade unit and the preset stress threshold and the wind turbine blade finite element model, a target fine mesh entity unit sub-model is constructed. model; finally, the phase field model and the Lagrangian-cohesion model are used to perform structural damage analysis on the target fine-grid entity unit sub-model, and the structural damage analysis results of the target wind turbine blade are generated; based on the above scheme, by comparing the Mises stress value at the Gaussian integration point of the blade unit at the current time with the preset stress threshold, the key positions where damage may occur in the blade (i.e., marked units) can be identified in real time, and the target fine-grid entity unit sub-model is automatically constructed in the high stress level stage, and the phase field model and the Lagrangian-cohesion model are used to perform structural damage analysis, which can improve the efficiency of wind turbine blade structural damage and sub-model analysis while ensuring the calculation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0047] Figure 1 A flowchart of the steps of a wind turbine blade structural damage analysis method based on a sub-model provided in the first embodiment of the present invention;

[0048] Figure 2 A schematic diagram of the Saint-Venant principle provided in Example 1 of the present invention;

[0049] Figure 3 A schematic diagram of the sub-model construction process provided in the first embodiment of the present invention;

[0050] Figure 4 A schematic diagram of a bilinear stress-separation curve provided in Example 1 of the present invention;

[0051] Figure 5A schematic flow chart of a method for analyzing wind turbine blade structure damage based on a sub-model provided in the first embodiment of the present invention;

[0052] Figure 6 This is a structural block diagram of a wind turbine blade structural damage analysis device based on a sub-model provided in the second embodiment of the present invention. DETAILED DESCRIPTION

[0053] The embodiments of the present invention provide a method and device for analyzing wind turbine blade structural damage based on a sub-model, which are used to solve the technical problems of low efficiency of existing wind turbine blade structural damage and sub-model analysis.

[0054] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0055] See also Figure 1 , Figure 1 A flowchart of the steps of a sub-model-based wind turbine blade structural damage analysis method provided in Example 1 of the present invention.

[0056] The present invention provides a method for analyzing wind turbine blade structure damage based on a sub-model, comprising:

[0057] Step 101: Obtain design parameters of a fan blade, and construct a finite element model of the fan blade according to the design parameters of the fan blade.

[0058] Specifically, step 101 may include the following sub-steps S11-S16:

[0059] Step S11: determining the coordinates of discrete cross-sectional points of a plurality of blade airfoils based on the design parameters of the wind turbine blades;

[0060] Step S12: determining cross-sectional curves of the plurality of blade airfoils according to the coordinates of the cross-sectional discrete points of the plurality of blade airfoils;

[0061] Step S13: translating and rotating the cross-sectional curves of the plurality of blade airfoils, and outputting a plurality of adjusted cross-sectional curves of the blade airfoils;

[0062] Step S14: constructing a wind turbine blade CAD model based on the cross-sectional curves of the plurality of adjusted blade airfoils;

[0063] Step S15: Meshing the wind turbine blade CAD model to determine the meshed wind turbine blade CAD model;

[0064] Step S16: performing composite material layer laying on the meshed wind turbine blade CAD model, and outputting a finite element model of the wind turbine blade.

[0065] It should be noted that to improve computational efficiency, the CAD (Computer-Aided Design) model of a wind blade is a three-dimensional surface model. The specific steps for constructing a wind blade CAD model are as follows: First, determine the design parameters of the wind blade based on actual needs. These parameters include blade length, airfoil cross-sectional shape, chord length distribution, and twist angle distribution. These parameters can typically be obtained using aerodynamic design software (such as Profili). Using software such as Profili, the coordinates of the discrete cross-sectional points of the blade airfoil are generated. These coordinates are then imported into the CAD software, and the cross-sectional curves of each airfoil are drawn. The cross-sectional positions are then adjusted through operations such as translation and rotation to ensure that the aerodynamic centers of all sections coincide. The CAD software's lofting function is then used to connect these adjusted cross-sectional curves of the blade airfoil to generate a smooth three-dimensional surface, thereby obtaining the CAD model of the wind blade.

[0066] Furthermore, since the wind turbine blade CAD model is composed of surfaces, shell elements are used for meshing. When meshing the wind turbine blade CAD model, quadrilateral meshes are used in the main body of the blade to take advantage of their advantages in regular areas; triangular meshes are used in complex geometric areas such as the blade tip to ensure mesh quality and calculation accuracy. Specifically, the entire wind turbine blade CAD model is first divided into quadrilateral meshes. If certain areas of the wind turbine blade CAD model (such as the blade tip) experience severe mesh distortion when using quadrilateral meshes, triangular meshes can be used instead to ensure mesh quality and calculation accuracy. In addition, composite materials are required to lay up the blades. Structurally, the blade can be subdivided into four major parts: the web, leading edge, main beam, and trailing edge. Therefore, the material type, layup thickness, and angle of each part vary. Based on this, a finite element model of the wind turbine blade, i.e., a global model of the wind turbine blade, is constructed.

[0067] Step 102: Based on a preset fluid load calculation method, perform stress calculation on the wind turbine blade finite element model to determine the fluid load and the Mises stress values ​​at the current time at the Gaussian integration points of multiple blade elements in the wind turbine blade finite element model.

[0068] The preset fluid load calculation method includes empirical formula and fluid-solid coupling calculation method.

[0069] Specifically, step 102 may include the following sub-steps S21-S22:

[0070] Step S21: Calculate the fluid load on the finite element model of the wind turbine blade based on an empirical formula or a fluid-solid coupling calculation method to determine the fluid load;

[0071] Step S22: Apply the fluid load to the wind turbine blade finite element model and perform explicit finite element analysis to determine the Mises stress values ​​at the current time at the Gaussian integration points of multiple blade units in the wind turbine blade finite element model.

[0072] It should be noted that the finite element model of the wind turbine blade constructed based on the above steps obtains the fluid load acting on the blade using empirical formulas or fluid-structure interaction calculations. This fluid load is then applied to the wind turbine blade finite element model, and explicit finite element analysis is performed on the model to obtain the Von Mises stress values ​​at the Gaussian integration points of multiple blade elements at the current time (i.e., the Von Mises stress value at each Gaussian integration point of each blade element). During the finite element analysis, the blade exhibits a strong fluid-structure interaction effect under the action of the fluid load. Due to differences in materials and layup schemes in different parts of the wind turbine blade, such as the material, number of plies, thickness, and angle of the web and main beam, the stress distribution is extremely complex, making stress concentration very likely to occur. In stress concentration areas, local stresses can far exceed the average stress level of the material, even reaching the yield strength or tensile strength of the material, accelerating the initiation and propagation of cracks.

[0073] Step 103: construct a target fine-grid solid element sub-model based on the fluid load, the comparison result between the Mises stress value at the Gaussian integration point of each blade element at the current time and the preset stress threshold, and the wind turbine blade finite element model.

[0074] Specifically, step 103 may include the following sub-steps S31-S34:

[0075] Step S31, comparing the Mises stress value at the Gaussian integration point of each blade unit at the current time with a preset stress threshold;

[0076] Step S32: taking as a marking unit any blade unit corresponding to the Mises stress value at the current time at any Gaussian integral point that is greater than or equal to a preset stress threshold;

[0077] Step S33: based on the airfoil section where the marked unit is located, convert the coarse-mesh shell unit in the wind turbine blade finite element model into a fine-mesh solid unit to generate an initial fine-mesh solid unit sub-model;

[0078] Step S34: Use the displacement of the wind turbine blade finite element model as the boundary condition of the initial fine-mesh entity unit sub-model, apply the fluid load as the external load on the surface of the initial fine-mesh entity unit sub-model, transfer the stress value at the current time at the Gaussian integration point in the area corresponding to the initial fine-mesh entity unit sub-model to the initial fine-mesh entity unit sub-model based on linear interpolation, and perform composite material layering on the initial fine-mesh entity unit sub-model to generate a target fine-mesh entity unit sub-model.

[0079] The preset stress threshold is 60% of the material's tensile strength or yield strength.

[0080] It should be noted that to proactively identify potential structural damage risks, prevent accidental failure before reaching its ultimate strength, and improve computational efficiency, this invention does not incorporate a damage model into the finite element analysis of the global wind blade model (the wind blade finite element model). Instead, it uses whether the Von Mises stress value at the current Gaussian integration point reaches 60% of the material's tensile strength or yield strength as the criterion for potential structural damage. When the stress level (the Von Mises stress value at the current Gaussian integration point) reaches or exceeds this threshold, irreversible damage accumulation may begin within the material. This damage may expand with stress cycling or over time, ultimately leading to the formation of macrocracks and structural failure. In addition, in order to achieve automatic identification and automatic construction in the process of converting the global model to the sub-model, the following operations are taken: During the finite element analysis process, each time a time step is calculated (each time the current time is recorded), the Von Mises stress values ​​of the current time at the Gaussian integration points of all blade units in the global model of the wind turbine blade are traversed, and it is judged whether the Von Mises stress values ​​of the current time at the Gaussian integration points of the blade units are greater than or equal to 60% of the tensile strength or compressive strength of the material (preset stress threshold), which is used as a criterion for whether structural damage may occur.

[0081] Furthermore, when it is identified that the Von Mises stress at the current time on a Gaussian integration point of a certain blade unit does not exceed 60% of the tensile strength or compressive strength of the material, it is determined that structural damage is unlikely to occur at this location, and the next time step is entered to continue the finite element analysis of the global model of the wind turbine blade; when it is identified that the Von Mises stress at the current time on a Gaussian integration point of a certain blade unit is greater than or equal to 60% of the tensile strength or compressive strength of the material, it is determined that this location is a key location (marked unit) where structural damage may occur, that is, any blade unit corresponding to the Mises stress value at the current time at any Gaussian integration point that is greater than or equal to the preset stress threshold is used as a marked unit.

[0082] Furthermore, considering that the wind turbine blade is mainly composed of multiple airfoil segments, a sub-model is automatically constructed based on an airfoil segment near the marked unit. In order to improve the calculation accuracy, the sub-model is converted from coarse-mesh shell elements to fine-mesh solid elements, and composite material plying is also performed to accurately simulate the structural characteristics of the wind turbine blade. Specifically, based on the airfoil segment where the marked unit is located, the coarse-mesh shell elements in the original global model are converted into fine-mesh solid elements, thereby obtaining an initial fine-mesh solid element sub-model, and the displacement of the global model is used as the driving variable (that is, the displacement of the global model is set as the boundary condition of the initial fine-mesh solid element sub-model), the fluid pressure load (fluid load) is applied as an external load on the surface of the initial fine-mesh solid element sub-model, and the stress value at the Gaussian integral point (that is, the initial fine mesh solid element sub-model) is set as the boundary condition of the initial fine mesh solid element sub-model. The stress value at the Gaussian integration point at the current time in the area corresponding to the grid entity unit sub-model is transmitted to the initial fine grid entity unit sub-model in real time by linear interpolation, and then the composite material is laid on the initial fine grid entity unit sub-model to obtain the target fine grid entity unit sub-model, where the stress value at the Gaussian integration point at the current time in the area is the stress at all Gaussian integration points in the area corresponding to the sub-model in the global model (including the stress components of six degrees of freedom, i.e., the normal stress along the x-axis, y-axis, and z-axis directions and the shear stress acting on the xy plane, xz plane, and yz plane, which can be obtained by finite element calculation). The corresponding area of ​​the sub-model is shown in the attached manual. Figure 3 Neutron model B is shown in the red box.

[0083] It is worth mentioning that the submodel is based on the Saint-Venant principle. The Saint-Venant principle states that if the actual distributed load is replaced by an equivalent load, the stress and strain will only change near the location where the load is applied, while the effects far away from the load area can be ignored, such as Figure 2 Based on this principle, the sub-modeling technology requires that the cutting boundary should be far away from the stress concentration area, so as to ensure that the stress and strain distribution inside the sub-model is more accurate.

[0084] Furthermore, according to Saint-Venant’s principle, the global model solution can be extrapolated to the sub-model as follows: Figure 3 As shown in Figure 1, the structure is divided into two different regions – the primary region and the secondary region. These regions are identified as the global model A and the fine mesh sub-model B. Sub-model B is created by refining the mesh of the partitioned global model A.

[0085] Further, if Figure 3 As shown, element J in the global model A contains four nodes, j1, j2, j3, and j4. The driving node B1 is located in element J. According to the interpolation method, the displacement at time t can be expressed as:

[0086] ; (1)

[0087] in, is the displacement of the driving node B1 at time t; and are the displacement components of the driving node B1 in the x and y directions respectively.

[0088] Furthermore, node j i The displacement of element J at time t is expressed as:

[0089] ; (2)

[0090] in, For node j i The displacement on element J at time t; and Node j i Displacement components in the x and y directions.

[0091] Therefore, the displacement of the driving node B1 in equation (1) is calculated by interpolation:

[0092] ; (3)

[0093] in, For node j i The shape function of the elements in the global model.

[0094] In formula (3) Represents the shape function of the elements in the global model, defined as:

[0095] ; (4)

[0096] in, is the shape function of the element in the global model of node j1; is the shape function of the element in the global model of node j2; is the shape function of the element in the global model of node j3; is the shape function of the element in the global model of node j4; and Represents the nodal coordinates of node j on element J in the global model.

[0097] Step 104 : Perform structural damage analysis on the target fine-grid entity unit sub-model using the phase field model and the Lagrangian-cohesion model to generate a target wind turbine blade structural damage analysis result.

[0098] Specifically, step 104 may include the following sub-steps S41-S45:

[0099] Step S41: using a phase field model to perform intra-layer damage simulation on the target fine-grid entity unit sub-model, and outputting the intra-layer damage simulation results;

[0100] Step S42: using the Lagrangian-cohesion model to perform interlaminar damage simulation on the target fine-grid entity unit sub-model to generate interlaminar damage simulation results;

[0101] Step S43: Based on the coupling effect of the intra-layer damage simulation results and the inter-layer damage simulation results, a wind blade structural damage analysis is performed on the target fine-grid entity element sub-model, an initial wind blade structural simulation refinement analysis result is generated, and the current time is recorded in real time;

[0102] Step S44: determine whether the current time reaches the preset phenomenon time;

[0103] Step S45: If yes, the initial fan blade structure simulation refinement analysis result is used as the target fan blade structure damage analysis result.

[0104] It should be noted that when performing sub-model meshing, it is important to ensure that the mesh size at the airfoil sub-model boundary matches the mesh size of the global model. Furthermore, a finer mesh should be applied to areas near cells where damage may occur to ensure accurate capture of the local stress distribution. Therefore, during this process, the mesh transition issue must be addressed to avoid computational errors caused by sudden changes in mesh size. On this basis, a phase field model is introduced to simulate intralaminar damage, and a Lagrangian-cohesion model is used to simulate interlaminar damage. The coupling effect of these two types of damage is considered to refine the damage simulation of the wind blade structure and obtain the initial refined analysis results of the wind blade structure simulation. Based on the principles of sub-modeling technology, the displacement on the global model is used as the driving variable and transferred to the sub-model boundary in real time through linear interpolation. Fluid loads are also applied to perform a refined analysis of the wind blade airfoil segment structural damage. This method fully utilizes the advantages of sub-modeling technology and can effectively improve the analysis accuracy of local areas while reducing the overall computational workload.

[0105] After completing the detailed structural analysis of the fan blade airfoil, it is necessary to determine whether the current moment (current time) recorded in real time has reached the preset phenomenon time (preset phenomenon time). If so, the calculation is terminated, and the initial fan blade structural simulation detailed analysis results determined when the current time reaches the preset phenomenon time (preset phenomenon time) are used as the target fan blade structural damage analysis results. The preset phenomenon time refers to the time interval from the start to the end of the simulation.

[0106] Optionally, it also includes:

[0107] If the current time does not reach the preset phenomenon time, the wind turbine blade finite element model is updated based on the linear interpolation method using the stress value of the Gaussian integration point of each blade unit at the current time, the displacement, velocity and acceleration of the finite element node corresponding to each blade unit, and a new wind turbine blade finite element model is determined;

[0108] Jumping to the step of performing stress calculation on the wind blade finite element model based on a preset fluid load calculation method, and determining Mises stress values ​​at the current time at Gaussian integration points of multiple blade elements in the wind blade finite element model, until the current time reaches a preset phenomenon time;

[0109] The initial fan blade structure simulation refinement analysis result determined when the current time reaches the preset phenomenon time is used as the target fan blade structure damage analysis result.

[0110] The stress value at the Gaussian integration point of the blade unit at the current time includes stress components of six degrees of freedom, namely, normal stress along the x-axis, y-axis, and z-axis directions and shear stress acting on the xy plane, xz plane, and yz plane. The stress components of the six degrees of freedom can be obtained through finite element calculation.

[0111] It should be noted that if it is not reached, the next time step is entered, and the global model unit information of the fan blade at the current time step (current time) (that is, the stress of the Gaussian integration point at the current time in each unit and the displacement, velocity and acceleration of the finite element node) is transferred to the corresponding regional unit of the sub-model by linear interpolation, so as to realize the update of the global model. Specifically, the finite element model of the fan blade is updated by linear interpolation using the stress of the Gaussian integration point at the current time of each blade unit and the displacement, velocity and acceleration of the finite element node corresponding to each blade unit, and a new finite element of the fan blade is obtained. The update process of the global model (the finite element model of the wind blade) is specifically as follows: the unit information of the global model of the wind blade at the current time step (i.e., the stress of the Gaussian integration point in each unit at the current time and the displacement, velocity, and acceleration of the finite element node) is transferred to the corresponding regional unit of the sub-model. After completing the update of the finite element model of the wind blade, the above steps are repeated to continue the finite element solution, that is, jump to step 102 until the current time reaches the preset phenomenon time; the initial wind blade structure simulation refinement analysis result determined when the current time reaches the preset phenomenon time is used as the target wind blade structure damage analysis result.

[0112] It is worth mentioning that, assuming the structure contains n nodes, the displacement vector of the entire structure can be expressed as:

[0113] ; (5)

[0114] in, is the displacement vector of the entire structure; , , ,……, are the displacement vectors corresponding to nodes 1, 2, 3, ..., n respectively.

[0115] Furthermore, the present invention adopts the phase field-Lagrangian-cohesive coupling method to simulate the intra-layer / inter-layer damage coupling behavior of the wind turbine blade. The corresponding weak form governing equation is as follows:

[0116] ; (6)

[0117] ; (7)

[0118] in, The object of study, in this invention, specifically refers to the entity unit sub-model of the airfoil section of the fan blade (i.e., the target fine grid entity unit sub-model); For the interface; It represents a binary parameter. When the value is 0, it means that the interface is not damaged and the displacement continuity is controlled by the Lagrange multiplier. When the value is 1, it means that damage has occurred and the subsequent interface mechanical behavior is controlled by the cohesive force model. and represent the Lagrange multiplier and cohesive stress respectively; and Represent the density and volume force of the material respectively; the acceleration vector , is the partial derivative, For time; is the external load acting on the boundary; is the energy degradation function; is the derivative of the energy degradation function; is the effective crack driving force; is the energy release rate; is the crack area density function; is the stress tensor; is the strain tensor; is the volume; is the area; is the crack opening displacement; is the displacement vector; is the boundary; d is the damage variable.

[0119] When simulating intralaminar damage in composite blades, a phase field model is used. A crack area density function is introduced to regularize the discrete cracks. This function is direction-dependent. The formula for the crack area density function is as follows:

[0120] ; (8)

[0121] in, is the crack area density function; is the fracture phase field; is the fracture phase field gradient; is a constant; is the crack geometry function; is the length scale factor; is the structure tensor, , is the penalty stiffness, M is the unit normal vector of the weak plane;

[0122] Based on the above foundation, the elastic energy density caused by deformation of the material is divided into two parts: the energy density caused by tensile deformation and the energy density caused by and the energy density caused by compression deformation , and their formulas are as follows:

[0123] ; (9)

[0124] Among them, different energy density functions are mainly determined by Young's modulus and shear modulus, 、 、 and, are the energy density components in the longitudinal tensile, transverse tensile, transverse shear, and longitudinal shear directions, respectively, and the subscript L indicates longitudinal fracture; and represent matrix cracking of mode I and mode II, respectively; , It represents the square of the positive part of the normal stress s1 in the 1 direction (usually the x direction). is the elastic modulus in the x direction; , It represents the square of the positive part of the y-direction normal stress s2 in the 2-direction (usually the y-direction). is the elastic modulus in the y direction; , is the square of the shear stress of the material in the x and y directions, is the shear modulus in the xy plane; , is the square of the shear stress of the material in the y and z directions, is the shear modulus in the yz plane; and are the energy density components of longitudinal compression and transverse compression respectively; , is the square of the negative positive part of the normal stress s1 in the x-direction; , is the square of the negative positive part of the normal stress s2 in the y direction; is the portion of energy density caused by compression deformation, , It is the square of the normal stress s3 in the z direction (usually the z direction); represents the non-shear related damage energy density, , is the square of the shear stress of the material in the x and z directions; is the shear-related damage energy density, , Poisson's ratio, subscript 12 indicates the ratio of the transverse strain in the 2nd direction (usually the y direction) to the longitudinal strain when the 1st direction (usually the x direction) is stretched or compressed. It is also the Poisson's ratio, which means the ratio of the transverse strain in the 3rd direction (z direction) to the strain in the 1st direction (x direction) when the 1st direction (x direction) is stretched or compressed. is the normal stress in the x-direction, is the normal stress in the y direction, is the normal stress in the z direction. Introducing the energy degradation function right Perform degenerate processing and derive the phase field driving force F based on this:

[0125] ; (10)

[0126] in, is the energy release rate corresponding to failure mode i, is the energy degradation function corresponding to failure mode i, and different failure modes use the same energy degradation function. Failure mode i includes longitudinal tensile failure mode L, mode I matrix cracking failure mode , Mode I matrix crack failure form , longitudinal shear failure form TL.

[0127] Furthermore, the present invention adopts the Lagrangian-cohesion model to simulate interlayer damage such as delamination and debonding of wind turbine blades. The Lagrangian-cohesion model strictly guarantees the continuity of interface displacement by applying Lagrangian constraints before cracks occur, thereby effectively overcoming the numerical defects of artificial compliance in traditional cohesion models. The model can efficiently handle the interface non-matching grid problem caused by adaptive encryption by constructing master-slave Lagrangian node pairs in real time. At the nth time step, the slave node interface force expression contributed by Lagrangian is:

[0128] ; (11)

[0129] in, Slave nodal interface forces contributing to the Lagrangian; is the shape function of the Lagrangian domain; and are the displacements of the i-th node on the master surface corresponding to a given slave node and the predicted displacement of the slave node at the n-th time step; is the total number of nodes on the master plane corresponding to a given slave node; is the nodal force contributed by the adjacent node pair at the (n-1)th time step; and are the masses of the i-th node on the master surface and the corresponding slave node; is the time step.

[0130] On this basis, the cohesive force model uses a biased bilinear stress-separation curve to characterize the progressive interlaminar damage mechanical behavior of composite materials, such as Figure 4 This curve uses the quadratic stress criterion to calculate the initial effective opening of the crack. :

[0131] ; (12)

[0132] Among them, the normalized normal initial displacement , is the initial normal stress, is the elastic stiffness; normalized tangential initial displacement , is the initial stress in the tangential direction; is the crack mode mixing coefficient; is the normal displacement; is the initial normal displacement; is the initial tangential displacement.

[0133] By the power criterion, the maximum effective crack opening displacement The formula for this is as follows, exceeding this value may indicate crack growth:

[0134] ; (13)

[0135] in, is the tensile critical energy release rate; is the shear critical energy release rate; is the damage mode coefficient.

[0136] Normal cohesion :

[0137] ; (14)

[0138] in, is the damage variable, , is the normalized effective crack opening at initiation, is the critical value of the normalized crack initiation effective opening; is the normalized normal displacement, , is the normal displacement, is the normalized initial displacement.

[0139] Tangential cohesion :

[0140] ; (15)

[0141] in, is the normalized tangential displacement, , is the tangential displacement, is the normalized tangential initial displacement.

[0142] Aiming at the coupled behavior of intra-layer / inter-layer cracks in composite materials, the present invention realizes coupling by describing the constitutive relationship of the cohesive force model that depends on the fracture phase field. The specific implementation method is: introducing the energy degradation function that depends on the fracture phase field into the original biased bilinear stress-separation criterion, then the interface energy density It can be expressed as:

[0143] ; (16)

[0144] in, is the energy degradation function defined in the stress-separation criterion of the cohesion model; is the energy degradation function that depends on the crack opening d; is the energy density corresponding to failure modes I and II; is the compressed energy density.

[0145] As a comparison of technical effects, it can be combined with existing technologies for reference. Sub-model technology is an effective numerical analysis method. By dividing the complex overall structure into several sub-structures and modeling and analyzing each sub-structure separately, it can significantly reduce the consumption of computing resources without reducing the overall analysis accuracy. In the study of wind turbine blade structural damage, sub-model technology can establish detailed local models for the key structural parts of the blade, thereby performing local refined analysis of wind turbine blades under complex working conditions. In addition, sub-model technology can also easily introduce different damage models and material properties, providing strong support for studying blade damage mechanisms and optimizing structural design.

[0146] At present, there are few studies on the refined analysis of wind turbine blade structural damage based on sub-models at home and abroad, but scholars' research on other structures and sub-models has certain inspiration and reference significance for the present invention. For example, Liu et al. proposed a fatigue analysis method based on the finite element sub-model method to study the local fatigue behavior of the adhesive joints at the trailing edge of composite wind turbine blades. Chen Qian et al. used sub-model technology to propose an accurate and fast finite element analysis method and device for the foundation model of floating wind turbines. Dong Leiting et al. proposed a fatigue crack propagation prediction method and system for key parts of aircraft fatigue damage based on sub-model technology and principal component analysis dimensionality reduction. It can quickly and accurately predict the stress intensity factor of the crack front under complex loads, and effectively balance the calculation accuracy and efficiency.

[0147] Domestic and foreign scholars have conducted some research on fatigue damage and sub-modeling technology for wind turbine blades and other structures. However, in the study by Liu et al., although they used sub-models to study wind turbine blades, they were limited to the fatigue behavior of the adhesive joints at the trailing edge of the blades, without considering other blade structures and their damage. In the study by Chen Qian et al., the research object was the foundation of a floating wind turbine, and damage was not considered. In addition, although Dong Leiting et al. used sub-modeling methods to study structural damage, they studied fatigue damage and the research object was an aircraft. The sub-models used in existing studies are constructed based on the entire phenomenon time range, and even at low stress levels, a complete calculation process is still required. Therefore, the efficiency of this calculation method is relatively low.

[0148] To address the above issues, the present invention proposes a wind turbine blade structural damage analysis method based on a sub-model. In the field of wind power, this method can identify key locations where structural damage may occur in real time during the finite element calculation of wind turbine blades, automatically construct an airfoil segment sub-model at high stress levels, and analyze the intra-layer and inter-layer damage of the airfoil segment. This method can improve calculation efficiency while ensuring calculation accuracy. Figure 5 In the process of finite element analysis of the global model of a wind turbine blade with coarse-grid shell elements, the key locations where damage may occur on the blade are identified in real time. In the high stress level stage, a fine-grid solid element sub-model is automatically constructed based on the airfoil segment near the element. The phase field model is introduced to simulate intra-layer damage, and the Lagrangian-cohesion model is introduced to simulate inter-layer damage, and the coupling effect of the two cracks is considered.

[0149] In summary, existing wind turbine blade sub-model research is mainly aimed at the fatigue behavior of blades, and the sub-models used by most research institutes are constructed based on the entire phenomenon time range. Even at low stress levels, a complete calculation process is still required. This process often requires additional time and has low calculation efficiency. Compared with the existing technology, the present invention can improve calculation efficiency while ensuring calculation accuracy. This method can identify the key positions where damage may occur on the blade in real time during the finite element analysis of the global model of the coarse-grid shell unit wind turbine blade, and automatically construct a fine-grid solid unit sub-model based on the airfoil segment near the unit in the high stress level stage. The phase field model is introduced to simulate intra-layer damage, the Lagrangian-cohesion model is used to simulate inter-layer damage, and the coupling effect of the two cracks is considered. The technical solution of the present invention can enrich the theoretical connotation of wind turbine blade structural damage and provide support for its structural optimization design and performance improvement.

[0150] In an embodiment of the present invention, the present invention provides a sub-model-based wind blade structural damage analysis method. First, the wind blade design parameters are obtained, and a wind blade finite element model is constructed based on the wind blade design parameters. Then, based on a preset fluid load calculation method, a stress calculation is performed on the wind blade finite element model to determine the fluid load and the Mises stress value at the current time at the Gaussian integration point of multiple blade units in the wind blade finite element model. Based on the comparison results between the fluid load, the Mises stress value at the current time at the Gaussian integration point of each blade unit and the preset stress threshold and the wind blade finite element model, a target fine mesh entity unit is constructed. submodel; finally, the phase field model and the Lagrangian-cohesion model are used to perform structural damage analysis on the target fine-grid entity unit submodel, and the structural damage analysis results of the target wind turbine blade are generated; based on the above scheme, by comparing the Mises stress value at the current time at the Gaussian integration point of the blade unit with the preset stress threshold, the key positions where damage may occur in the blade (i.e., marked units) can be identified in real time, and the target fine-grid entity unit submodel is automatically constructed in the high stress level stage, and the phase field model and the Lagrangian-cohesion model are used to perform structural damage analysis, which can improve the efficiency of wind turbine blade structural damage and submodel analysis while ensuring the calculation accuracy.

[0151] See also Figure 6 , Figure 6 This is a structural block diagram of a wind turbine blade structural damage analysis device based on a sub-model provided in the second embodiment of the present invention.

[0152] The present invention provides a wind turbine blade structural damage analysis device based on a sub-model, comprising:

[0153] An acquisition module 601 is used to acquire design parameters of a wind turbine blade and construct a finite element model of the wind turbine blade according to the design parameters of the wind turbine blade;

[0154] A stress output module 602 is configured to perform stress calculation on the wind turbine blade finite element model based on a preset fluid load calculation method, and determine the fluid load and the Mises stress values ​​at the current time at the Gaussian integration points of multiple blade elements in the wind turbine blade finite element model;

[0155] The sub-model construction module 603 is used to construct a target fine-grid solid element sub-model based on the fluid load, the comparison result between the Mises stress value at the Gaussian integration point of each blade element and the preset stress threshold at the current time, and the wind turbine blade finite element model;

[0156] The analysis module 604 is used to perform structural damage analysis on the target fine grid entity unit sub-model using the phase field model and the Lagrangian-cohesion model to generate a target wind turbine blade structural damage analysis result.

[0157] Furthermore, the acquisition module 601 is specifically configured to:

[0158] Based on the design parameters of the wind turbine blades, the coordinates of the discrete cross-section points of multiple blade airfoils are determined;

[0159] determining cross-sectional curves of the plurality of blade airfoils according to the coordinates of the cross-sectional discrete points of the plurality of blade airfoils;

[0160] translating and rotating the cross-sectional curves of the plurality of blade airfoils, and outputting a plurality of adjusted cross-sectional curves of the blade airfoils;

[0161] Constructing a CAD model of a wind turbine blade based on the cross-sectional curves of the multiple adjusted blade airfoils;

[0162] Meshing the fan blade CAD model to determine the fan blade CAD model after meshing;

[0163] Composite material layers are laid on the meshed CAD model of the wind turbine blade, and the finite element model of the wind turbine blade is output.

[0164] Furthermore, the preset fluid load calculation method includes an empirical formula and a fluid-solid coupling calculation method; the stress output module 602 is specifically used to:

[0165] Calculate the fluid load on the finite element model of the wind turbine blade based on empirical formulas or fluid-solid coupling calculation methods to determine the fluid load;

[0166] Fluid loads are applied to a finite element model of a wind turbine blade and explicit finite element analysis is performed to determine the Mises stress values ​​at the current time at Gaussian integration points of multiple blade elements in the finite element model of the wind turbine blade.

[0167] Furthermore, the sub-model construction module 603 is specifically used to:

[0168] Compare the Mises stress value at the Gaussian integration point of each blade element at the current time with the preset stress threshold;

[0169] The blade element corresponding to the Mises stress value at the current time at any Gaussian integral point that is greater than or equal to the preset stress threshold is used as a marked element;

[0170] Based on the airfoil section where the marked element is located, the coarse-mesh shell elements in the wind turbine blade finite element model are converted into fine-mesh solid elements to generate an initial fine-mesh solid element sub-model;

[0171] The displacement of the finite element model of the wind turbine blade is used as the boundary condition of the initial fine-mesh solid unit sub-model, and the fluid load is applied as the external load on the surface of the initial fine-mesh solid unit sub-model. The stress value at the Gaussian integration point in the region corresponding to the initial fine-mesh solid unit sub-model at the current time is transferred to the initial fine-mesh solid unit sub-model based on linear interpolation. The initial fine-mesh solid unit sub-model is then laminated with composite materials to generate the target fine-mesh solid unit sub-model.

[0172] Furthermore, the analysis module 604 is specifically configured to:

[0173] Use the phase field model to simulate the intra-layer damage of the target fine-grid solid element sub-model and output the intra-layer damage simulation results;

[0174] The Lagrangian-cohesive force model is used to simulate interlaminar damage on the target fine-grid solid element sub-model to generate interlaminar damage simulation results;

[0175] Based on the coupling effect of the intra-layer damage simulation results and the inter-layer damage simulation results, the wind blade structural damage analysis is performed on the target fine-grid solid element sub-model, and the refined analysis results of the initial wind blade structural simulation are generated, and the current time is recorded in real time;

[0176] Determine whether the current time reaches the preset phenomenon time;

[0177] If so, the refined analysis results of the initial fan blade structure simulation are used as the damage analysis results of the target fan blade structure.

[0178] In an optional embodiment of the device, the device further comprises:

[0179] The first module is used to update the wind turbine blade finite element model based on the linear interpolation method by using the stress value of the Gaussian integration point of each blade unit at the current time and the displacement, velocity and acceleration of the finite element node corresponding to each blade unit if the current time does not reach the preset phenomenon time, so as to determine a new wind turbine blade finite element model;

[0180] The second module is used to jump to the step of performing stress calculation on the wind turbine blade finite element model based on a preset fluid load calculation method, and determining the Mises stress value at the current time at the Gaussian integration points of multiple blade units in the wind turbine blade finite element model, until the current time reaches a preset phenomenon time;

[0181] The third module is used to use the initial fan blade structure simulation refinement analysis result determined when the current time reaches the preset phenomenon time as the target fan blade structure damage analysis result.

[0182] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and modules can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0183] An embodiment of the present invention also provides a computer device, including a memory and a processor, wherein a computer program is stored in the memory; when the computer program is executed by the processor, the processor executes the steps of the wind blade structural damage analysis method based on the sub-model as described in any of the above embodiments.

[0184] An embodiment of the present invention further provides a computer-readable storage medium having a computer program / instruction stored thereon. When the computer program / instruction is executed by a processor, the steps of the wind turbine blade structural damage analysis method based on a sub-model as in any of the above embodiments are implemented.

[0185] An embodiment of the present invention further provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the wind turbine blade structural damage analysis method based on a sub-model as in any of the above embodiments.

[0186] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0187] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0188] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wind turbine blade structural damage analysis method based on a sub-model, characterized in that: include: Acquiring fan blade design parameters, and constructing a fan blade finite element model based on the fan blade design parameters; Based on a preset fluid load calculation method, a stress calculation is performed on the finite element model of the wind turbine blade to determine the fluid load and the Mises stress values ​​at the current time at the Gaussian integration points of multiple blade elements in the finite element model of the wind turbine blade; Constructing a target fine-grid entity unit sub-model according to the fluid load, a comparison result between the Mises stress value at the Gaussian integration point of each blade unit at the current time and a preset stress threshold, and the wind turbine blade finite element model; The phase field model and the Lagrangian-cohesion model are used to perform structural damage analysis on the target fine-grid entity element sub-model to generate a target wind turbine blade structural damage analysis result.

2. The wind turbine blade structural damage analysis method based on sub-model according to claim 1 is characterized in that: The step of constructing a finite element model of a fan blade according to the fan blade design parameters includes: Determining the coordinates of discrete points of a plurality of blade airfoils' cross sections based on the fan blade design parameters; Determining cross-sectional curves of a plurality of blade airfoils according to the coordinates of the cross-sectional discrete points of the plurality of blade airfoils; translating and rotating the cross-sectional curves of the plurality of blade airfoils, and outputting a plurality of adjusted cross-sectional curves of the blade airfoils; Constructing a CAD model of a wind turbine blade according to the cross-sectional curves of the plurality of adjusted blade airfoils; Meshing the fan blade CAD model to determine the meshed fan blade CAD model; Composite material layers are laid on the meshed wind turbine blade CAD model to output a finite element model of the wind turbine blade.

3. The wind turbine blade structural damage analysis method based on sub-model according to claim 1 is characterized in that: The preset fluid load calculation method includes an empirical formula and a fluid-solid coupling calculation method; the stress calculation is performed on the wind turbine blade finite element model based on the preset fluid load calculation method to determine the fluid load and the Mises stress values ​​at the current time at the Gaussian integration points of multiple blade units in the wind turbine blade finite element model, including: Performing fluid load calculation on the fan blade finite element model based on an empirical formula or a fluid-solid coupling calculation method to determine the fluid load; The fluid load is applied to the wind turbine blade finite element model and an explicit finite element analysis is performed to determine the Mises stress values ​​at the current time at the Gaussian integration points of multiple blade units in the wind turbine blade finite element model.

4. The wind turbine blade structural damage analysis method based on sub-model according to claim 1 is characterized in that: The method of constructing a target fine-grid entity unit sub-model according to the fluid load, a comparison result between the Mises stress value at the current time at the Gaussian integration point of each blade unit and a preset stress threshold, and the wind turbine blade finite element model, comprises: Comparing the Mises stress value at the Gaussian integration point of each blade element at the current time with a preset stress threshold; The blade unit corresponding to the Mises stress value at the current time at any Gaussian integral point that is greater than or equal to the preset stress threshold is used as a marking unit; Based on the airfoil section where the marked unit is located, the coarse-mesh shell unit in the wind turbine blade finite element model is converted into a fine-mesh solid unit to generate an initial fine-mesh solid unit sub-model; The displacement of the wind turbine blade finite element model is used as the boundary condition of the initial fine-mesh entity unit sub-model, the fluid load is applied as the external load on the surface of the initial fine-mesh entity unit sub-model, the stress value at the current time at the Gaussian integration point in the area corresponding to the initial fine-mesh entity unit sub-model is transferred to the initial fine-mesh entity unit sub-model based on linear interpolation, and composite material layup is performed on the initial fine-mesh entity unit sub-model to generate a target fine-mesh entity unit sub-model.

5. The wind turbine blade structural damage analysis method based on sub-model according to claim 1 is characterized in that: The phase field model and the Lagrangian-cohesion model are used to perform structural damage analysis on the target fine-grid entity element sub-model to generate the target wind turbine blade structural damage analysis results, including: Using a phase field model to simulate intra-layer damage on the target fine-grid entity unit sub-model, and outputting the intra-layer damage simulation results; Using a Lagrangian-cohesive force model to simulate interlaminar damage on the target fine-grid entity element sub-model, and generating interlaminar damage simulation results; Based on the coupling effect of the intra-layer damage simulation results and the inter-layer damage simulation results, performing a wind blade structural damage analysis on the target fine-grid entity element sub-model, generating an initial wind blade structural simulation refinement analysis result, and recording the current time in real time; Determine whether the current time reaches the preset phenomenon time; If so, the refined analysis result of the initial fan blade structure simulation is used as the target fan blade structure damage analysis result.

6. The wind turbine blade structural damage analysis method based on sub-model according to claim 5 is characterized in that: Also includes: If the current time does not reach the preset phenomenon time, the finite element model of the wind turbine blade is updated based on the stress value of the Gaussian integral point of each blade unit at the current time, the displacement, velocity and acceleration of the finite element node corresponding to each blade unit, and a new finite element model of the wind turbine blade is determined; Jumping to the step of performing stress calculation on the wind turbine blade finite element model based on the preset fluid load calculation method, and determining the Mises stress values ​​at the current time at the Gaussian integration points of multiple blade elements in the wind turbine blade finite element model, until the current time reaches the preset phenomenon time; The initial fan blade structure simulation refinement analysis result determined when the current time reaches the preset phenomenon time is used as the target fan blade structure damage analysis result.

7. A wind turbine blade structural damage analysis device based on a sub-model, characterized in that: include: An acquisition module is used to acquire design parameters of the fan blades and construct a finite element model of the fan blades according to the design parameters of the fan blades; a stress output module, configured to perform stress calculation on the wind turbine blade finite element model based on a preset fluid load calculation method, and determine the fluid load and the Mises stress values ​​at the current time at Gaussian integration points of a plurality of blade elements in the wind turbine blade finite element model; a sub-model construction module, configured to construct a target fine-grid entity unit sub-model based on the fluid load, a comparison result between the Mises stress value at the Gaussian integration point of each blade unit at the current time and a preset stress threshold, and the wind turbine blade finite element model; The analysis module is used to perform structural damage analysis on the target fine grid entity unit sub-model using a phase field model and a Lagrangian-cohesion model to generate a target wind turbine blade structural damage analysis result.

8. A computer device, characterized in that: It comprises a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the processor executes the steps of the wind turbine blade structure damage analysis method based on the sub-model as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed, the sub-model-based wind turbine blade structural damage analysis method according to any one of claims 1 to 6 is implemented.

10. A computer program product, characterized in that The computer program product includes a computer program stored on a non-transitory computer-readable storage medium, wherein the computer program includes program instructions, wherein when the program instructions are executed by a computer, the computer is caused to execute the sub-model-based wind blade structural damage analysis method according to any one of claims 1 to 6.

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