A sub-model-based fan blade structure damage analysis method and device

Abstract

The application discloses a fan blade structure damage analysis method and device based on a submodel, and is used for solving the technical problem of low analysis efficiency of the existing fan blade structure damage and submodel. 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, determining fluid load and Mises stress values at current time of Gaussian integral points of each blade unit in the fan blade finite element model; according to a comparison result between the fluid load, the Mises stress values at the current time of the Gaussian integral points of each blade unit and a preset stress threshold value, and the fan blade finite element model, dynamic construction of a target fine grid solid element submodel is completed, and structure damage analysis of the target fine grid solid element submodel is performed in combination with a phase field model and a Lagrange-cohesion model, and a target fan blade structure damage analysis result is generated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wind power generation technology, and in particular to a wind turbine blade structure damage analysis method and device based on a submodel. BACKGROUND

[0002] As a clean and renewable energy technology, wind power generation has been favored by countries around the world. As the main component of the wind turbine, the wind turbine blade is prone to structural damage such as fiber breakage, matrix cracking, and adhesive debonding during operation due to its complex aerodynamic effects and blade elasticity, which significantly affects the efficiency and safety of the wind turbine.

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

[0004] Existing wind turbine blade structural damage analysis methods are mainly focused on the fatigue behavior of the blade, and most of the submodels used in research are based on the entire phenomenon time range. Even at low stress levels, a complete calculation process is still required, which consumes a large amount of time and results in low efficiency of wind turbine blade structural damage and submodel analysis. SUMMARY

[0005] The present application provides a wind turbine blade structural damage analysis method and device based on a submodel, which solves the technical problem of low efficiency of existing wind turbine blade structural damage and submodel analysis.

[0006] The present application provides a wind turbine blade structural damage analysis method and device based on a submodel, which solves the technical problem of low efficiency of existing wind turbine blade structural damage and submodel analysis.

[0007] Obtain the wind turbine blade design parameters, and construct a wind turbine blade finite element model according to the wind turbine blade design parameters;

[0008] Based on the pre-set fluid load calculation method, the stress of the wind turbine blade finite element model is calculated to determine the fluid load and the current time Mises stress value at the Gauss integral point of each blade element in the wind turbine blade finite element model;

[0009] According to the comparison results between the fluid load, the current time Mises stress value at the Gauss integral point of each blade element and the pre-set stress threshold value, and the wind turbine blade finite element model, a target fine mesh solid element submodel is constructed.

[0010] Perform structural damage analysis on the target fine grid entity element submodel by using the phase field model and the Lagrangian-cohesion force model to generate the target wind turbine blade structural damage analysis result.

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

[0012] Determining the cross-sectional discrete point coordinates of a plurality of blade airfoils based on the wind turbine blade design parameters;

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

[0014] Performing translation and rotation on the cross-sectional curves of a plurality of blade airfoils to output the cross-sectional curves of a plurality of adjusted blade airfoils;

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

[0016] Performing mesh division on the wind turbine blade CAD model to determine the mesh-divided wind turbine blade CAD model;

[0017] Performing composite material layering on the mesh-divided wind turbine blade CAD model to output a wind turbine blade finite element model.

[0018] Optionally, the preset fluid load calculation method comprises an empirical formula and a fluid-structure coupling calculation method; and the 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 current time Mises stress value at the Gaussian integration point of each blade element in the wind turbine blade finite element model comprises:

[0019] Performing fluid load calculation on the wind turbine blade finite element model based on the empirical formula or the fluid-structure coupling calculation method to determine the fluid load;

[0020] Applying the fluid load on the wind turbine blade finite element model and performing explicit finite element analysis to determine the current time Mises stress value at the Gaussian integration point of each blade element in the wind turbine blade finite element model.

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

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

[0023] corresponding to the Mises stress value of the current time at any Gaussian integral point greater than or equal to the preset stress threshold as a marked unit;

[0024] based on the airfoil section where the marked unit is located, converting the coarse mesh shell unit in the fan blade finite element model into a fine mesh solid unit to generate an initial fine mesh solid unit submodel;

[0025] the displacement of the fan blade finite element model as the boundary condition of the initial fine mesh solid unit submodel, the fluid load as an external load applied to the surface of the initial fine mesh solid unit submodel, the stress value of the current time at the Gaussian integral point in the region corresponding to the initial fine mesh solid unit submodel is transmitted to the initial fine mesh solid unit submodel based on the linear interpolation method, and the initial fine mesh solid unit submodel is subjected to composite layering to generate a target fine mesh solid unit submodel.

[0026] Optionally, the phase field model and the Lagrangian-cohesion model are used to perform structural damage analysis on the target fine mesh solid unit submodel to generate a target fan blade structural damage analysis result, including:

[0027] The phase field model is used to perform intralaminar damage simulation on the target fine mesh solid unit submodel, and an intralaminar damage simulation result is output;

[0028] The Lagrangian-cohesion model is used to perform interlaminar damage simulation on the target fine mesh solid unit submodel to generate an interlaminar damage simulation result;

[0029] Based on the coupling effect of the intralaminar damage simulation result and the interlaminar damage simulation result, the target fine mesh solid unit submodel is subjected to fan blade structural damage analysis to generate an initial fan blade structural simulation refinement analysis result, and the current time is recorded in real time;

[0030] determine whether the current time reaches a preset phenomenon time;

[0031] If yes, the initial fan blade structural simulation refinement analysis result is taken as a target fan blade structural damage analysis result.

[0032] Optionally, it further includes:

[0033] If the current time does not reach the preset phenomenon time, the stress value of the current time at the Gaussian integral point of each blade unit, the displacement, velocity and acceleration of the finite element node corresponding to each blade unit are used to update the fan blade finite element model based on the linear interpolation method to determine a new fan blade finite element model;

[0034] jumping to perform the step of calculating stress of the fan blade finite element model based on the preset fluid load calculation method, determining the Mises stress value at the Gauss integral point of each blade element in the fan blade finite element model at the current time until the current time reaches the preset phenomenon time;

[0035] taking 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.

[0036] The second aspect of the present application provides a fan blade structure damage analysis device based on a submodel, comprising:

[0037] The obtaining module is configured to obtain fan blade design parameters, and construct a fan blade finite element model according to the fan blade design parameters.

[0038] The stress output module is configured to calculate stress of the fan blade finite element model based on a preset fluid load calculation method, and determine the Mises stress value at the Gauss integral point of each blade element in the fan blade finite element model at the current time.

[0039] The submodel construction module is configured to construct a target fine-grid solid element submodel according to the fluid load, the comparison result between the Mises stress value at the Gauss integral point of each blade element at the current time and a preset stress threshold, and the fan blade finite element model.

[0040] The analysis module is configured to perform structural damage analysis on the target fine-grid solid element submodel by using a phase field model and a Lagrangian-cohesion model, and generate a target fan blade structure damage analysis result.

[0041] The third aspect of the present application provides a computer device, comprising a memory and a processor, the memory stores a computer program, and the computer program is executed by the processor to make the processor execute the steps of the fan blade structure damage analysis method based on a submodel.

[0042] The fourth aspect of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed to realize the steps of the fan blade structure damage analysis method based on a submodel.

[0043] The fifth aspect of the present application provides a computer program product, which comprises a computer program stored on a non-transitory computer readable storage medium, and the computer program comprises program instructions, wherein when the program instructions are executed by a computer, the computer executes the steps of the fan blade structure damage analysis method based on a submodel.

[0044] From the above technical solutions, the present application has the following advantages:

[0045] The above technical solutions of the present application provide a fan blade structure damage analysis method based on a submodel. First, the fan blade design parameters are obtained, and a fan blade finite element model is constructed according to the fan blade design parameters. Then, based on a preset fluid load calculation method, the stress of the fan blade finite element model is calculated to determine the fluid load and the Mises stress value at the current time of the Gauss integral points of multiple blade elements in the fan blade finite element model. According to the comparison results between the fluid load, the Mises stress value at the current time of the Gauss integral points of each blade element and the preset stress threshold value, and the fan blade finite element model, a target fine grid solid element submodel is constructed. Finally, the phase field model and the Lagrange-cohesion model are used to analyze the structure damage of the target fine grid solid element submodel to generate the target fan blade structure damage analysis result. Based on the above scheme, by comparing the Mises stress value at the current time of the Gauss integral points of the blade elements with the preset stress threshold value, the key position (i.e. the marked element) where the blade may be damaged can be identified in real time. The target fine grid solid element submodel is automatically constructed at the high stress level stage, and the structure damage analysis is performed using the phase field model and the Lagrange-cohesion model, which can improve the fan blade structure damage and submodel analysis efficiency while ensuring the calculation accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0047] Figure 1 A step flow chart of a fan blade structure damage analysis method based on a submodel provided by the first embodiment of the present application is provided.

[0048] Figure 2 A schematic diagram of the Saint-Venant principle provided by the first embodiment of the present application is provided.

[0049] Figure 3 A schematic diagram of the submodel construction process provided by the first embodiment of the present application is provided.

[0050] Figure 4 A schematic diagram of the bilinear stress-separation curve provided by the first embodiment of the present application is provided.

[0051] Figure 5A flowchart of a sub-model-based fan blade structure damage analysis method provided for the first embodiment of the present application is shown in the figure.

[0052] Figure 6 A structural block diagram of a sub-model-based fan blade structure damage analysis device provided for the second embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0053] The embodiments of the present application provide a sub-model-based fan blade structure damage analysis method and device, and aim to solve the technical problem of low efficiency of existing fan blade structure damage and sub-model analysis.

[0054] In order to make the purposes, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the embodiments described below are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0055] Please refer to Figure 1 , Figure 1 A step flowchart of a sub-model-based fan blade structure damage analysis method provided for the first embodiment of the present application is shown in the figure.

[0056] The sub-model-based fan blade structure damage analysis method provided by the present application comprises the following steps.

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

[0058] Specifically, step 101 can comprise the following sub-steps S11-S16.

[0059] Step S11: Determine the coordinates of the cross-sectional discrete points of a plurality of blade airfoils based on the fan blade design parameters.

[0060] Step S12: Determine the 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: Translate and rotate the cross-sectional curves of the plurality of blade airfoils, and output the cross-sectional curves of the plurality of adjusted blade airfoils.

[0062] Step S14: Construct a fan blade CAD model according to the cross-sectional curves of the plurality of adjusted blade airfoils.

[0063] Step S15: Divide the grid of the fan blade CAD model, and determine the fan blade CAD model after grid division.

[0064] Step S16, composite material plies are laid on the fan blade CAD model after meshing, and a fan blade finite element model is output.

[0065] It should be noted that, in order to improve the calculation efficiency, the fan blade CAD (Computer-Aided Design) model is a three-dimensional curved surface model. The specific steps of constructing the fan blade CAD model are as follows: first, the design parameters of the fan blade are determined according to actual needs, including blade length, airfoil cross-sectional shape, chord length distribution, twist angle distribution, etc. These parameters can usually be obtained through aerodynamic design software (such as Profili). The cross-sectional discrete point coordinates of the blade airfoil are generated through Profili and other software, which are imported into the CAD software to draw the cross-sectional curves of each airfoil (blade airfoil cross-sectional curves), and the position of the cross section is adjusted through translation, rotation and other operations to ensure that the aerodynamic centers of all cross sections coincide. Then the lofting function of the CAD software is used to connect these adjusted blade airfoil cross-sectional curves to generate smooth three-dimensional surfaces, thereby obtaining the CAD model of the fan blade.

[0066] Further, since the fan blade CAD model is composed of surfaces, shell elements are used for meshing. When meshing the fan blade CAD model, quadrilateral meshes are used in the main body of the blade to take advantage of their regular regions; triangular meshes are used in complex geometric regions such as the tip to ensure mesh quality and calculation accuracy. Specifically, the entire fan blade CAD model is first divided into quadrilateral meshes, and if the mesh distortion is severe when some regions (such as the tip) of the fan blade CAD model are divided into quadrilateral meshes, triangular meshes can be used for division to ensure mesh quality and calculation accuracy. In addition, the blade needs to be laid with composite materials. Structurally, the blade can be subdivided into four parts: web, leading edge, main beam and trailing edge, so the types of materials, ply thickness and angle of different parts are different. Based on this, the fan blade finite element model, i.e. the fan blade global model, is constructed.

[0067] Step 102, based on the preset fluid load calculation method, stress calculation is performed on the fan blade finite element model to determine the fluid load and the Mises stress value at the current time at the Gauss integration point of each blade element in the fan blade finite element model.

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

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

[0070] Step S21, performing fluid load calculation on the fan blade finite element model based on an empirical formula or a fluid-structure coupling calculation method to determine the fluid load;

[0071] Step S22, applying the fluid load on the fan blade finite element model and performing explicit finite element analysis to determine the Von Mises stress value at the Gauss integral point of each blade element at the current time.

[0072] It should be noted that the fan blade finite element model constructed based on the above steps, the fluid load acting on the blade is obtained according to the empirical formula or the fluid-structure coupling calculation, the fluid load acting on the blade is applied to the fan blade finite element model, and the explicit finite element analysis is performed on the fan blade finite element model, so that the Von Mises stress value at the Gauss integral point of each blade element at the current time (i.e. the Von Mises stress value at the Gauss integral point of each blade element) is obtained. In the process of finite element analysis, the blade shows strong fluid-structure coupling effect under the action of fluid load. Due to the difference of materials and layup scheme of different parts of fan blade, for example, the materials, number of plies, ply thickness and angle of web and main beam are different, so that the stress distribution is extremely complex, and stress concentration phenomenon is easy to occur. In the stress concentration area, the local stress may be far more than the average stress level of the material, and even reach the yield strength or tensile strength of the material, accelerating the crack generation and propagation of the material.

[0073] Step 103, constructing a target fine grid solid element sub-model according to the fluid load, the comparison result between the Von Mises stress value at the Gauss integral point of each blade element at the current time and the preset stress threshold, and the fan blade finite element model.

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

[0075] Step S31, comparing the Von Mises stress value at the Gauss integral point of each blade element at the current time with the preset stress threshold;

[0076] Step S32, taking the blade element corresponding to the Von Mises stress value at the Gauss integral point at the current time greater than or equal to the preset stress threshold as a marked element;

[0077] Step S33, converting the coarse grid shell element in the fan blade finite element model into a fine grid solid element based on the airfoil section where the marked element is located, to generate an initial fine grid solid element sub-model;

[0078] Step S34, taking the displacement of the fan blade finite element model as the boundary condition of the initial fine mesh solid element sub-model, applying the fluid load as the external load on the surface of the initial fine mesh solid element sub-model, transferring the stress value at the Gauss integral point in the corresponding area of the initial fine mesh solid element sub-model at the current time to the initial fine mesh solid element sub-model based on linear interpolation, and performing composite material layering on the initial fine mesh solid element sub-model to generate the target fine mesh solid element sub-model.

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

[0080] It should be noted that, in order to identify the potential damage risk of the structure in advance, prevent the structure from being damaged accidentally before reaching its ultimate strength, and improve the calculation efficiency, the present application does not introduce a damage model in the finite element analysis of the fan blade global model (fan blade finite element model), but uses whether the Von Mises stress value at the Gauss integral point at the current time reaches or exceeds 60% of the tensile strength or yield strength of the material as the standard for possible structural damage. When the stress level (the Von Mises stress value at the Gauss integral point at the current time) reaches or exceeds this threshold, irreversible damage accumulation may occur inside the material, and these damages may expand over time or with stress cycles, eventually leading to the formation of macroscopic cracks and the failure of the structure. In addition, in order to realize automatic identification and automatic construction during the process of global model to sub-model, the following operations are taken: during the finite element analysis process, the Von Mises stress value at the Gauss integral point at the current time of all blade elements of the fan blade global model is calculated (the current time is recorded once), and it is judged whether the Von Mises stress value at the Gauss integral point at the current time of the blade element is greater than or equal to 60% of the tensile strength or compressive strength of the material (the preset stress threshold), which is used as the standard for possible structural damage.

[0081] Further, when it is identified that the Von Mises stress at the Gauss integral point at the current time of a certain blade element does not exceed 60% of the tensile strength or compressive strength of the material, it is determined that structural damage is not possible at this location, and the next time step is entered to continue the finite element analysis of the fan blade global model; when it is identified that the Von Mises stress at the Gauss integral point at the current time of a certain blade element is greater than or equal to 60% of the tensile strength or compressive strength of the material, it is determined that this place is a key position (marked element) where structural damage is possible, that is, any blade element corresponding to the Von Mises stress value at the Gauss integral point at the current time greater than or equal to the preset stress threshold is taken as a marked element.

[0082] Further, since the fan blade is mainly composed of multiple airfoil segments, then a submodel is automatically constructed based on one airfoil segment near the marked unit. In order to improve the calculation accuracy, the submodel is converted from the coarse mesh shell element to the fine mesh solid element, and the composite material layup is also performed to accurately simulate the structural characteristics of the fan blade. Specifically, based on the airfoil segment where the marked unit is located, the coarse mesh shell element in the original global model is converted to the fine mesh solid element, thereby obtaining an initial fine mesh solid element submodel. The displacement of the global model is taken as the driving variable (i.e. the displacement of the global model is set as the boundary condition of the initial fine mesh solid element submodel), the fluid pressure load (fluid load) is applied as the external load on the surface of the initial fine mesh solid element submodel, and the stress value at the current time at the Gauss integration point in the region corresponding to the initial fine mesh solid element submodel is transmitted to the initial fine mesh solid element submodel in real time through linear interpolation, and then the composite material layup is performed on the initial fine mesh solid element submodel to obtain a target fine mesh solid element submodel. The stress value at the current time at the Gauss integration point in the region is the stress (including six degrees of freedom stress components, i.e. normal stress along the x-axis, y-axis and z-axis directions and shear stress acting on the x-y plane, x-z plane and y-z plane) on all Gauss integration points in the corresponding region of the submodel in the global model, which can be obtained by finite element calculation. The corresponding region of the submodel is shown in the red box of the submodel B in FIG. 1. Figure 3

[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 load application position, and the influence far away from the load application area can be ignored, as shown in FIG. 2. Based on this principle, the submodel technology requires that the cutting boundary should be far away from the stress concentration area, so as to ensure the accurate distribution of stress and strain inside the submodel. Figure 2

[0084] Further, according to the Saint-Venant principle, the global model solution can be extrapolated to the submodel, as follows: as shown in FIG. 3, the structure is divided into two different regions - the main region and the secondary region. These regions are identified as the global model A and the fine mesh submodel B respectively. The submodel B is created by refining the mesh of the partitioned global model A. Figure 3

[0085] Further, as shown in FIG. 4, the element J in the global model A contains four nodes, j1, j2, j3, j4. The driving node B1 is located in the element J. According to the interpolation method, the displacement at time t can be expressed as: Figure 3

[0086] ; (1) ​​​​

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

[0088] Further, the displacement of the node j i on element J at time t is denoted as:

[0089] ; (2)

[0090] where, is the displacement of the node j i on element J at time t; and are the displacement components of the node j i in x and y directions, respectively.

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

[0092] ; (3)

[0093] where, is the shape function of element in the global model of the node j i .

[0094] In equation (3), Nj represents the shape function of element in the global model, which is defined as:

[0095] ; (4)

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

[0097] Step 104, using the phase field model and the Lagrangian-cohesion force model to perform structural damage analysis on the target fine mesh entity element sub-model, and generating a target wind turbine blade structural damage analysis result.

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

[0099] Step S41, in-plane damage simulation is performed on the target fine-grid entity element submodel by using the phase field model, and in-plane damage simulation results are output;

[0100] Step S42, interlayer damage simulation is performed on the target fine-grid entity element submodel by using the Lagrange-cohesion model, and interlayer damage simulation results are generated;

[0101] Step S43, based on the coupling effect of the in-plane damage simulation results and the interlayer damage simulation results, wind turbine blade structure damage analysis is performed on the target fine-grid entity element submodel, initial wind turbine blade structure simulation refinement analysis results are generated, and the current time is recorded in real time;

[0102] Step S44, it is judged whether the current time reaches the preset phenomenon time;

[0103] Step S45, if yes, the initial wind turbine blade structure simulation refinement analysis results are taken as the target wind turbine blade structure damage analysis results.

[0104] It should be noted that when the submodel grid is divided, attention should be paid to the fact that the grid size of the airfoil section submodel boundary should match the grid size of the global model. At the same time, the area near the element where damage may occur should be divided into finer grids to ensure that the local stress distribution can be accurately captured. Therefore, in this process, the grid transition problem must be solved to avoid calculation errors caused by sudden changes in grid size. On this basis, the phase field model is introduced to simulate in-plane damage, and the Lagrange-cohesion model is used to simulate interlayer damage, and the coupling effect of the two damages is considered to simulate the refinement analysis of the wind turbine blade structure damage, and the initial wind turbine blade structure simulation refinement analysis results are obtained. Based on the principle of submodel technology, the displacement on the global model is taken as the driving variable and is transmitted to the submodel boundary in real time through linear interpolation, and the fluid load is also applied, so as to carry out refinement analysis on the wind turbine blade airfoil section structure damage. This method makes full use of the advantages of submodel technology, which can effectively improve the analysis accuracy of local area and reduce the overall calculation amount.

[0105] Further, after completing the structure refinement analysis of the wind turbine blade airfoil section, it is judged whether the current time (current time) recorded in real time has reached the preset phenomenon time (preset phenomenon time). If it has reached, the calculation is terminated, and the initial wind turbine blade structure simulation refinement analysis results determined when the current time reaches the preset phenomenon time (preset phenomenon time) are taken as the target wind turbine blade structure damage analysis results. The preset phenomenon time refers to the time interval covered from the beginning to the end of the simulation.

[0106] Optionally, it further comprises:

[0107] If the current time does not reach the preset phenomenon time, the stress value of the current time at the Gauss integral point of each blade element is adopted based on a linear interpolation manner, the displacement, velocity and acceleration of the finite element node corresponding to each blade element are adopted to update the finite element model of the fan blade, and a new finite element model of the fan blade is determined.

[0108] The jump execution is based on a preset fluid load calculation method to calculate the stress of the fan blade finite element model, and the step of determining the current time Mises stress value at the Gauss integral point of the plurality of blade elements in the fan blade finite element model is performed until the current time reaches the preset phenomenon time.

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

[0110] The stress value of the current time at the Gauss integral point of the blade element includes six degrees of freedom stress components, i.e. normal stress along x-axis, y-axis and z-axis, and shear stress acting on x-y plane, x-z plane and y-z plane, and the six degrees of freedom stress components can be obtained by finite element calculation.

[0111] It should be noted that if it is not reached, the next time step is entered, and the fan blade global model element information (i.e. the stress of the current time at the Gauss integral point in each element and the displacement, velocity and acceleration of the finite element node) of the current time step (current time) is transmitted to the submodel corresponding area element by linear interpolation, thereby realizing the update of the global model. Specifically, the stress of the current time at the Gauss integral point of each blade element and the displacement, velocity and acceleration of the finite element node corresponding to each blade element are used to update the finite element model of the fan blade by linear interpolation, and a new finite element model of the fan blade is obtained, and the update process of the global model (the finite element model of the fan blade) is realized. The specific process is as follows: the fan blade global model element information (i.e. the stress of the current time at the Gauss integral point in each element and the displacement, velocity and acceleration of the finite element node) of the current time step is transmitted to the submodel corresponding area element, and after the update of the fan blade finite element model is completed, the above steps are repeated to continue the finite element solution, i.e. the jump execution step 102 is performed until the current time reaches the preset phenomenon time; the initial fan blade structure simulation fine analysis result determined when the current time reaches the preset phenomenon time is taken as the target fan blade structure damage analysis result.

[0112] It is worth mentioning that the displacement vector of the entire structure can be expressed as:

[0113] ; (5)

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

[0115] Further, the present application adopts a phase field-Lagrange-cohesion coupling method to simulate the layer / in-layer damage coupling behavior of a fan blade, and corresponding weak form control equations are as follows:

[0116] ; (6)

[0117] ; (7)

[0118] wherein, is a research object, and in the present application, specifically refers to a solid element submodel (i.e., a target fine mesh solid element submodel) of a profile section of a fan blade; is an interface; represents a binary parameter, and when the value is 0, it indicates that the interface does not have damage, and the displacement continuity is controlled by a Lagrange multiplier, and when the value is 1, it indicates that damage occurs, and subsequent interface mechanical behavior is controlled by a cohesion model; and respectively represent a Lagrange multiplier and a cohesive stress; and respectively represent the density and the volume force of a material; and an acceleration vector , is a partial derivative, is time; is an external load acting on a boundary; is an energy degradation function; is a derivative of the energy degradation function; is an effective crack driving force; is an energy release rate; is a crack area density function; is a stress tensor; is a strain tensor; is a volume; is an area; is a crack opening displacement; is a displacement vector; is a boundary; and d is a damage variable.

[0119] In the simulation of the layer damage of a composite blade, a phase field model is adopted. A crack area density function is introduced to regularize the discrete cracks, and the function is related to a direction. The crack area density function formula is as follows:

[0120] ; (8)

[0121] where, is the crack area density function; is the crack phase field; is the crack phase field gradient; is a constant; is the crack geometry function; is the length scale coefficient; 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 generated by the deformation of the material is divided into two parts, which are the energy density caused by tensile deformation and the energy density caused by compression deformation , the formulas of which are as follows:

[0123] ; (9)

[0124] where different energy density functions are mainly determined by Young's modulus and shear modulus, , , and, are the energy density components of longitudinal tensile, transverse tensile, transverse shear and longitudinal shear, respectively, and the subscript L represents the longitudinal crack; and represent the matrix cracking of mode I and mode II, respectively; , represents the square of the positive value part of the normal stress s1 in the 1 direction (usually the x direction), is the elastic modulus in the x direction; , represents the square of the positive value part of the 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 of the xy plane; , is the square of the shear stress of the material in the y and z directions, is the shear modulus of the yz plane; and are the energy density components of longitudinal compression and transverse compression, respectively; , is the square of the negative positive value part of the normal stress s1 in the x direction; , is the square of the negative positive value part of the normal stress s2 in the y direction; is a part of the energy density caused by compressive deformation, , is the square of the z-direction normal stress s3; represents the non-shear related damage energy density, , is the square of the shear stress in the x and z directions; represents the shear related damage energy density, , is the Poisson's ratio, the subscript 12 represents the ratio of the transverse strain in the 2 direction (usually the y direction) to the longitudinal strain in the 1 direction (usually the x direction) when the 1 direction is subjected to tension or compression, is also the Poisson's ratio, representing the ratio of the transverse strain in the 3 direction (z direction) to the 1 direction strain when the 1 direction (x direction) is subjected to tension or compression, is the normal stress in the x direction, is the normal stress in the y direction, is the normal stress in the z direction. Introduce the energy degradation function to degradation processing, and based on this, derive the phase field driving force F:

[0125] ; (10)

[0126] wherein, 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, and failure mode i includes longitudinal tensile failure mode L, mode I matrix cracking failure mode , mode I matrix cracking failure mode , and longitudinal shear failure mode TL.

[0127] Further, the present application uses a Lagrangian-cohesion model to simulate delamination, debonding and other interlayer damage of a fan blade. The Lagrangian-cohesion model strictly ensures the continuity of the interface displacement by applying Lagrangian constraints before crack occurs, thereby effectively overcoming the artificial numerical defects of the traditional cohesive model. The model can efficiently handle the interface non-matching mesh problem caused by adaptive refinement by constructing master-slave Lagrangian node pairs in real time. At the nth time step, the slave node interface force contributed by the Lagrangian is expressed as:

[0128] ; (11)

[0129] wherein, is the slave node interface force contributed by the Lagrangian; is the shape function of the Lagrangian domain. and is the displacement of the given slave node corresponding to the i-th node on the master surface and the predicted displacement of the slave node at the n-th time step, respectively; is the total number of nodes on the master surface corresponding to the given slave node; is the nodal force contributed by the neighboring node pair at the (n-1)-th time step; and are the mass of the i-th node on the master surface and the corresponding slave node, respectively; is the time step.

[0130] On this basis, the cohesive model adopts a biased bilinear stress-separation curve to represent the progressive interlaminar damage mechanical behavior of the composite material, as shown in Figure 4 . The curve uses a quadratic stress criterion to calculate the initial effective opening of the crack :

[0131] ; (12)

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

[0133] Through the power criterion, the formula of the maximum effective opening displacement of the crack is as follows, which may mean crack propagation beyond this value:

[0134] ; (13)

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

[0136] The normal cohesive force :

[0137] ; (14)

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

[0139] The tangential cohesive force :

[0140] ; (15)

[0141] wherein, The normalized tangential displacement, , The tangential displacement, The normalized tangential initial displacement.

[0142] For the composite inter / intra-laminar crack coupling behavior, the present application realizes coupling through a constitutive relation capable of describing a cohesive force model dependent on a fracture phase field. The specific implementation method is: introducing an energy degradation function dependent on a fracture phase field into the original offset bilinear stress-separation quantity criterion, then the interface energy density Can be expressed as:

[0143] ; (16)

[0144] wherein, The energy degradation function defined in the stress-separation quantity criterion of the cohesive force model; The energy degradation function dependent on the crack opening d; The energy density corresponding to the failure modes I and II; The compression energy density.

[0145] As a comparison of technical effects, the prior art can be referred to. The submodel technology is an effective numerical analysis method, which can significantly reduce the consumption of computing resources without reducing the accuracy of the overall analysis by dividing the complex overall structure into several substructures and modeling and analyzing each substructure individually. In the research of fan blade structure damage, the submodel technology can establish a detailed local model for the key structure parts of the blade, so as to perform local fine analysis on the fan blade under complex working conditions. In addition, the submodel technology can also conveniently introduce different damage models and material properties, thereby providing strong support for the research of blade damage mechanism and the optimization of structure design.

[0146] Currently, there are few studies on the fine analysis of fan blade structural damage based on sub-models at home and abroad, but the studies of scholars on other structures and sub-models have certain enlightenment and reference significance for the present application. For example, Liu et al. proposed a fatigue analysis method based on the finite element sub-model method for studying the local fatigue behavior of the rear edge adhesive joint of a composite wind turbine blade. Chen Qian et al. proposed an accurate and fast floating wind turbine foundation model finite element analysis method and device using sub-model technology. Dong Lei et al. proposed a fatigue crack propagation prediction method and system for the key parts of the fatigue damage of an aircraft based on sub-model technology and principal component analysis dimension reduction, which can quickly and accurately predict the crack front stress intensity factor under complex load and effectively balance the calculation accuracy and efficiency.

[0147] Scholars at home and abroad have carried out certain research on the fatigue damage of fan blades and other structures and sub-model technology. However, in the research of Liu et al., although they used sub-models to study fan blades, it was limited to the fatigue behavior of the rear edge adhesive joint of the blade, and other structures of the blade and their damage were not considered. In the research of Chen Qian et al., the research object was the foundation of the floating wind turbine, and damage was not considered. In addition, although Dong Lei et al. used sub-model methods to study the damage of structures, they studied fatigue damage and the research object was an aircraft. The sub-models used in the existing research are constructed based on the entire phenomenon time range, and even at a low stress level, a complete calculation process is still required. Therefore, the efficiency of this calculation method is relatively low.

[0148] To solve the above problems, the present application proposes a fan blade structural damage analysis method based on sub-models, which can identify the key positions where structural damage may occur in real time during the finite element calculation process of the fan blade in the wind power field, automatically construct a airfoil segment sub-model at a high stress level stage, and analyze the interlaminar and interlaminar damage of the airfoil segment, thereby improving the calculation efficiency while ensuring the calculation accuracy. Specifically, please refer to Figure 5 In the process of finite element analysis of the global model of the coarse mesh shell element fan blade, the key positions where the blade may be damaged are identified in real time, a fine mesh solid element sub-model is automatically constructed based on the airfoil segment near the element at a high stress level stage, a phase field model is introduced to simulate interlaminar damage, a Lagrangian-cohesion model is introduced to simulate interlaminar damage, and the coupling effect of the two cracks is considered.

[0149] In summary, the existing fan blade submodel research is mainly aimed at the fatigue behavior of the blade, and the submodel adopted in most studies is constructed based on the entire phenomenon time range, that is, even under a low stress level, a complete calculation process is still required. This process often requires additional time and has low calculation efficiency. Compared with the prior art, the present application can improve the calculation efficiency while ensuring the calculation accuracy. The method can identify the key positions where damage may occur in the blade in real time in the process of finite element analysis of the global model of the coarse mesh shell element fan blade, automatically construct a fine mesh solid element submodel based on the airfoil segment near the element in the high stress level stage, introduce a phase field model to simulate the intralaminar damage, a Lagrangian-cohesion model to simulate the interlaminar damage, and consider the coupling effect of the two cracks. The technical scheme of the present application can enrich the theoretical connotation of the structural damage of the fan blade, and provide support for the structural optimization design and performance improvement thereof.

[0150] In the embodiment of the present application, a submodel-based fan blade structural damage analysis method is provided. First, the fan blade design parameters are obtained, and a fan blade finite element model is constructed according to the fan blade design parameters. Then, the stress calculation of the fan blade finite element model is performed based on a preset fluid load calculation method to determine the fluid load and the Mises stress value at the current time of the Gauss integral points of the plurality of blade elements in the fan blade finite element model. A target fine mesh solid element submodel is constructed according to the comparison results between the fluid load, the Mises stress value at the current time of the Gauss integral points of each blade element and the preset stress threshold value, and the fan blade finite element model. Finally, the phase field model and the Lagrangian-cohesion model are used to perform structural damage analysis on the target fine mesh solid element submodel to generate a target fan blade structural damage analysis result. Based on the above scheme, by comparing the Mises stress value at the current time of the Gauss integral points of the blade elements with the preset stress threshold value, the key positions (i.e., the marked elements) where damage may occur in the blade can be identified in real time, the target fine mesh solid element submodel can be automatically constructed in the high stress level stage, and the phase field model and the Lagrangian-cohesion model can be used for structural damage analysis, which can improve the fan blade structural damage and submodel analysis efficiency while ensuring the calculation accuracy.

[0151] Please refer to Figure 6 , Figure 6 A structural block diagram of a submodel-based fan blade structural damage analysis device according to Embodiment Two of the present application is provided.

[0152] The submodel-based fan blade structural damage analysis device provided by the present application comprises:

[0153] The obtaining module 601 is configured to obtain fan blade design parameters, and construct a fan blade finite element model according to the fan blade design parameters.

[0154] a stress output module 602, configured to perform stress calculation on the fan blade finite element model based on a preset fluid load calculation method, to determine a fluid load and a current time Mises stress value at a Gaussian integral point of each blade element in the fan blade finite element model;

[0155] a submodel construction module 603, configured to construct a target fine-grid solid element submodel according to the fluid load, a comparison result between the current time Mises stress value at the Gaussian integral point of each blade element and a preset stress threshold, and the fan blade finite element model;

[0156] an analysis module 604, configured to perform structural damage analysis on the target fine-grid solid element submodel by using a phase field model and a Lagrangian-cohesion model, to generate a target fan blade structural damage analysis result.

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

[0158] determine section discrete point coordinates of a plurality of blade airfoils based on fan blade design parameters;

[0159] determine section curves of the plurality of blade airfoils according to the section discrete point coordinates of the plurality of blade airfoils;

[0160] perform translation and rotation on the section curves of the plurality of blade airfoils, and output section curves of a plurality of adjusted blade airfoils;

[0161] construct a fan blade CAD model according to the section curves of the plurality of adjusted blade airfoils;

[0162] perform mesh division on the fan blade CAD model, to determine a mesh-divided fan blade CAD model;

[0163] perform composite material layering on the mesh-divided fan blade CAD model, to output a fan blade finite element model.

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

[0165] perform fluid load calculation on the fan blade finite element model based on the empirical formula or the fluid-structure coupling calculation method, to determine the fluid load;

[0166] apply the fluid load on the fan blade finite element model and perform explicit finite element analysis, to determine the current time Mises stress value at the Gaussian integral point of each blade element in the fan blade finite element model.

[0167] Further, the submodel construction module 603 is specifically configured to:

[0168] compare the Mises stress value of the current time at the Gaussian integral point of each blade unit with a preset stress threshold value;

[0169] mark the blade unit corresponding to the Mises stress value of the current time at the Gaussian integral point greater than or equal to the preset stress threshold value as a marked unit;

[0170] convert the coarse mesh shell element in the finite element model of the fan blade into a fine mesh solid element based on the airfoil section where the marked unit is located, to generate an initial fine mesh solid element submodel;

[0171] use the displacement of the fan blade finite element model as the boundary condition of the initial fine mesh solid element submodel, apply the fluid load as an external load on the surface of the initial fine mesh solid element submodel, transfer the stress value of the current time at the Gaussian integral point in the region corresponding to the initial fine mesh solid element submodel to the initial fine mesh solid element submodel in a linear interpolation manner, and perform composite material layering on the initial fine mesh solid element submodel to generate a target fine mesh solid element submodel.

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

[0173] perform in-layer damage simulation on the target fine mesh solid element submodel using the phase field model, and output the in-layer damage simulation result;

[0174] perform inter-layer damage simulation on the target fine mesh solid element submodel using the Lagrangian-cohesion model, to generate an inter-layer damage simulation result;

[0175] perform fan blade structure damage analysis on the target fine mesh solid element submodel based on the coupling effect of the in-layer damage simulation result and the inter-layer damage simulation result, to generate an initial fan blade structure simulation refined analysis result, and record the current time in real time;

[0176] determine whether the current time reaches a preset phenomenon time;

[0177] if yes, use the initial fan blade structure simulation refined analysis result as a target fan blade structure damage analysis result.

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

[0179] The first module is configured to, if the current time does not reach the preset phenomenon time, update the fan blade finite element model based on the stress value of the current time at the Gaussian integral point of each blade unit, the displacement, velocity and acceleration of the finite element node corresponding to each blade unit, to determine a new fan blade finite element model in a linear interpolation manner;

[0180] The second module is configured to jump to perform a preset fluid load calculation method-based stress calculation on the fan blade finite element model to determine the Mises stress value at the Gauss integral point of each blade unit in the fan blade finite element model at the current time until the current time reaches the preset phenomenon time.

[0181] The third module is configured to take 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 can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described device and module can refer to the corresponding process in the foregoing method embodiments, which will not be described herein.

[0183] The embodiment of the application further provides a computer device, including a memory and a processor, the memory stores a computer program; the computer program is executed by the processor, so that the processor executes the steps of the fan blade structure damage analysis method based on the submodel as in any one of the foregoing embodiments.

[0184] The embodiment of the application further provides a computer readable storage medium, which stores a computer program / instruction, and the computer program / instruction is executed by a processor to implement the steps of the fan blade structure damage analysis method based on the submodel as in any one of the foregoing embodiments.

[0185] The embodiment of the application further provides a computer program product, which includes a computer program / instruction, and the computer program / instruction is executed by a processor to implement the steps of the fan blade structure damage analysis method based on the submodel as in any one of the foregoing embodiments.

[0186] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other manners. For example, the above-described device embodiments are merely illustrative, and the division of units is merely a logical function division, and there can be another division manner in actual implementation, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0187] The units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0188] The above-described embodiments are only used to illustrate the technical solutions of the present application, but not to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for analyzing wind turbine blade structural damage based on a sub-model, characterized in that, The method comprises the following steps: acquiring fan blade design parameters and constructing a fan blade finite element model according to the fan blade design parameters; calculating stress of the fan blade finite element model based on a preset fluid load calculation method, determining a fluid load and a current time Mises stress value at a Gauss integral point of each blade element in the fan blade finite element model; constructing a target fine grid solid element submodel according to the fluid load, a comparison result between the current time Mises stress value at the Gauss integral point of each blade element and a preset stress threshold value, and the fan blade finite element model; performing structural damage analysis on the target fine grid solid element submodel by using a phase field model and a Lagrange-cohesion model to generate a target fan blade structural damage analysis result; the step of constructing a target fine grid solid element submodel according to the fluid load, a comparison result between the current time Mises stress value at the Gauss integral point of each blade element and a preset stress threshold value, and the fan blade finite element model comprises the following steps: comparing the current time Mises stress value at the Gauss integral point of each blade element with the preset stress threshold value; regarding a blade element corresponding to any current time Mises stress value at the Gauss integral point greater than or equal to the preset stress threshold value as a marked element; based on a wing profile section where the marked element is located, converting a coarse grid shell element in the fan blade finite element model into a fine grid solid element to generate an initial fine grid solid element submodel; applying the displacement of the fan blade finite element model as a boundary condition of the initial fine grid solid element submodel, applying the fluid load as an external load on the surface of the initial fine grid solid element submodel, transferring the current time stress value at the Gauss integral point in the region corresponding to the initial fine grid solid element submodel to the initial fine grid solid element submodel in a linear interpolation manner, and performing composite material layering on the initial fine grid solid element submodel to generate a target fine grid solid element submodel.

2. The submodel-based fan blade structure damage analysis method of claim 1, wherein, the step of constructing a fan blade finite element model according to the fan blade design parameters comprises the following steps: determining the coordinates of the cross-sectional discrete points of a plurality of blade airfoils based on the fan blade design parameters; determining the 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; performing translation and rotation on the cross-sectional curves of the plurality of blade airfoils to output the cross-sectional curves of the plurality of adjusted blade airfoils; constructing a fan blade CAD model according to the cross-sectional curves of the plurality of adjusted blade airfoils; dividing the grid of the fan blade CAD model to determine a grid-divided fan blade CAD model; performing composite material layering on the grid-divided fan blade CAD model to output a fan blade finite element model.

3. The submodel-based fan blade structure damage analysis method of claim 1, wherein, The preset fluid load calculation method includes an empirical formula and a fluid-structure coupling calculation method; based on the preset fluid load calculation method, stress calculation is performed on the fan blade finite element model to determine the fluid load and the Mises stress value at the current time at the Gaussian integral points of the plurality of blade elements in the fan blade finite element model, including: performing fluid load calculation on the fan blade finite element model based on an empirical formula or a fluid-structure coupling calculation method to determine the fluid load; applying the fluid load to the fan blade finite element model and performing explicit finite element analysis to determine the Mises stress value at the current time at the Gaussian integral points of the plurality of blade elements in the fan blade finite element model.

4. The submodel-based fan blade structure damage analysis method of claim 1, wherein, performing structural damage analysis on the target fine-grid entity element sub-model using a phase field model and a Lagrangian-cohesion force model to generate target fan blade structural damage analysis results, including: performing intralayer damage simulation on the target fine-grid entity element sub-model using a phase field model to output intralayer damage simulation results; performing interlayer damage simulation on the target fine-grid entity element sub-model using a Lagrangian-cohesion force model to generate interlayer damage simulation results; based on the coupling effect of the intralayer damage simulation results and the interlayer damage simulation results, performing fan blade structural damage analysis on the target fine-grid entity element sub-model to generate initial fan blade structural simulation refinement analysis results and record the current time in real time; determining whether the current time reaches a preset phenomenon time; if yes, the initial fan blade structural simulation refinement analysis results are taken as the target fan blade structural damage analysis results.

5. The submodel-based fan blade structure damage analysis method according to claim 4, characterized by, Further comprising: if the current time does not reach the preset phenomenon time, based on a linear interpolation method, the stress value at the current time at the Gaussian integral points of each blade element, the displacement, velocity and acceleration of the corresponding finite element nodes of each blade element are used to update the fan blade finite element model to determine a new fan blade finite element model; jumping to the step of performing stress calculation on the fan blade finite element model based on the preset fluid load calculation method to determine the Mises stress value at the current time at the Gaussian integral points of the plurality of blade elements in the fan blade finite element model until the current time reaches the preset phenomenon time; taking the initial fan blade structural simulation refinement analysis results determined when the current time reaches the preset phenomenon time as the target fan blade structural damage analysis results. 6.A sub-model based fan blade structure damage analysis device applied to the sub-model based fan blade structure damage analysis method of claim 1, characterized in that, including: an acquisition module configured to acquire fan blade design parameters and construct a fan blade finite element model based on the fan blade design parameters; a stress output module configured to perform stress calculation on the fan blade finite element model based on a preset fluid load calculation method to determine the fluid load and the Mises stress value at the current time at the Gaussian integral points of the plurality of blade elements in the fan blade finite element model; a sub-model construction module, configured to construct a target fine-grid solid element sub-model according to the fluid load, a comparison result between a current time Mises stress value at a Gauss integral point of each of the blade units and a preset stress threshold value, and the fan blade finite element model; an analysis module, configured to perform structural damage analysis on the target fine-grid solid element sub-model by using a phase field model and a Lagrange-cohesion model, and generate a target fan blade structural damage analysis result.

7. A computer device, comprising: A computer program product includes a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, wherein when the program instructions are executed by a computer, the computer performs the sub-model-based fan blade structural damage analysis method according to any one of claims 1-5.

8. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed to implement the sub-model-based fan blade structural damage analysis method according to any one of claims 1-5.

9. A computer program product, characterised in that, The computer program product includes a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, wherein when the program instructions are executed by a computer, the computer performs the sub-model-based fan blade structural damage analysis method according to any one of claims 1-5.

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