Design method of blade root prefabricated part of wind driven generator blade

Abstract

The invention discloses a design method of a blade root prefabricated part of a wind driven generator blade, and the method comprises the steps: firstly, creating a subpart analysis model of the blade root prefabricated part, the subpart analysis model comprises a model used for simulating at least two of a pre-embedded screw sleeve, a flexible part surrounding the periphery of the pre-embedded screw sleeve, a glass fiber reinforced plastic paving layer and a UD strip; a cohesion failure unit is introduced into a specified interface of the subcomponent analysis model, a load displacement boundary condition is applied to the subcomponent analysis model, and interface parameters representing the performance of the specified interface in the current state are obtained; under the condition that interface parameters of a specified interface meet design requirements, design parameters of structural parts in the sub-part analysis model are adjusted, the method can play a guiding role in optimization of design of blade root prefabricated parts such as pre-embedded thread sleeves and glass fiber reinforced plastic laying layers, then good working performance of the blade roots can be obtained, and the method is simple and easy to implement. And the consumed manpower and material resource cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of wind power generation, and in particular to a design method for a blade root prefabricated part of a wind generator blade. Background Art

[0002] As wind turbine blades become larger, the load on the blade root is also increasing. The embedded screw sleeve design gradually replaces the T-bolt connection and becomes the mainstream blade root connection method. Figure 1 , Figure 2 As shown, due to the weak interface bonding ability between metal and composite materials, a wavy or toothed concave-convex groove structure is generally processed on the outer surface of the embedded screw sleeve 1, and a glass fiber bundle is circumferentially wound to fill the surface groove of the bolt sleeve, which is then assembled with the UD strips 7 distributed along the circumferential direction of the pitch circle and the first fiberglass 4 and the second fiberglass 2 inside and outside the shell. The wedge-shaped area behind the bolt sleeve is filled with a core material strip 3 to provide structural rigidity while reducing weight.

[0003] Due to the complex structural composition and load-bearing mode of the embedded blade root, it is difficult to effectively evaluate the blade root as a whole at this stage. At the same time, in order to save testing costs, single or three embedded screw sleeves are usually selected as samples for extreme pull-out and pull-pull fatigue tests. Existing test results show that, under the premise of ensuring the safety of the bolts, the failure of the sample mainly occurs at the interface on both sides of the winding yarn, that is, the heterogeneous interface between the screw sleeve and the yarn, and the yarn and the fiberglass (or UD strip). At the same time, the test results show that changing the outer contour of the screw sleeve will greatly affect the interface performance between the winding yarn and the screw sleeve. Due to the poor interface bonding strength between metal and composite materials, if the outer contour of the screw sleeve does not have any structural design (flat straight line), the failure mode will occur at the winding yarn-screw sleeve interface.

[0004] The influence of the shape of the screw sleeve on the interface performance is usually qualitatively judged based on the contact area between the screw sleeve and the yarn. However, it is difficult to directly observe the failure form and internal damage evolution of the failed test sample from the outer surface in the prior art, and the failed sample often needs to be cut open to identify its internal change characteristics. In this way, the failure form at the cut fracture in the prior art cannot be judged whether it is caused by the test or the subsequent cutting process, which limits the further exploration of the structural type of the embedded screw sleeve by engineering designers.

[0005] Therefore, how to provide a method that can reliably guide the design of the embedded screw sleeve is a technical problem that needs to be solved urgently by technicians in this field. Summary of the invention

[0006] The object of the present invention is to provide a design method which can provide reliable guidance for the design of a blade root prefabricated part.

[0007] The present invention provides a design method for a blade root prefabricated part of a wind turbine blade, characterized in that the design method comprises:

[0008] Model creation step: creating a subcomponent analysis model of the blade root preform, wherein the subcomponent analysis model at least includes models for simulating at least two of the embedded screw sleeve, the flexible member wound around the circumference of the embedded screw sleeve, the fiberglass ply, and the UD strip;

[0009] Loading simulation step: introducing a cohesive failure unit to a designated interface of the subcomponent analysis model, and applying a load-displacement boundary condition to the subcomponent analysis model to obtain interface parameters characterizing the performance of the designated interface in a current state; wherein the load-displacement boundary condition can envelop the real load of the blade root in an actual operating condition;

[0010] Adjustment step: adjusting the design parameters of the structural member in the sub-component analysis model on the condition that the interface parameters of the designated interface meet the design requirements.

[0011] In the present invention, a sub-component analysis model located at the blade root prefabricated part is pre-established, and after a cohesive failure unit is introduced into a designated interface, a load-displacement boundary condition is applied to the sub-component analysis model to obtain interface parameters characterizing the performance of the designated interface in the current state, and whether the current state of the designated interface meets the design requirements is determined based on the interface parameters. If the design requirements are not met, the design parameters of at least one structural component in the prefabricated part are adjusted, so that the designated interface parameters finally meet the design requirements.

[0012] The present invention can obtain the rules between the specified interface strengths through the cohesive failure unit, which plays a guiding role in optimizing the design parameters of each structural member in the prefabricated part, and further can also obtain better working performance of the blade root. Moreover, the method is simple and the manpower and material costs are low.

[0013] Optionally, the input parameters of the cohesion failure unit are obtained by: conducting material-level tests on the specified interface performance according to the test standard to directly or indirectly fit and obtain the input parameters of the cohesion failure unit; the input parameters of the cohesion failure unit include: G IC , G IIC , G IIIC , η, where G IC , G IIC , G IIIC They represent the critical energy release rates of type I, type II, and type III crack extension, respectively. They represent the ultimate strength in the directions of crack extension of type I, type II, and type III respectively, and η represents the mixing ratio.

[0014] Optionally, the test standard includes ASTM D5528, ASTM D7905 or ASTM D6671.

[0015] Optionally, the cohesion failure unit is a cohesion unit having a predetermined thickness at the designated interface.

[0016] Alternatively, the cohesive failure unit is a cohesive unit with zero thickness at the designated interface.

[0017] Alternatively, the cohesive failure unit is a cohesive contact property of the designated interface.

[0018] Optionally, the subcomponent analysis model is a finite element model. In the loading simulation step, at least one of the mesh density, analysis step length, and viscosity regularization coefficient of the finite element model is adjusted to balance the computational iteration convergence and computational efficiency.

[0019] Optionally, the load in the load-displacement boundary condition includes at least one of a displacement load or a force load.

[0020] Optionally, the design parameters of the structural component in the sub-component analysis model include one or more of the outer contour parameters of the embedded screw sleeve, the winding method of the flexible component, the FRP ply structure shape, or the UD strip structure shape.

[0021] Optionally, the sub-component analysis model is a two-dimensional diagram, and the sub-component analysis model is an end view passing through the central axis of the embedded screw sleeve;

[0022] Alternatively, the subcomponent analysis model is a three-dimensional structure diagram.

[0023] Optionally, the cohesion failure unit uses a quadratic nominal stress criterion as a basis for judging the interface failure, and the quadratic nominal stress criterion formula is specifically:

[0024]

[0025] Among them, σ n ,σ s ,σ t Represents the stress components under the three crack extension directions of type I, type II, and type III respectively They represent the ultimate strength in the crack extension directions of type I, type II, and type III respectively;

[0026] Alternatively, the cohesion failure unit uses the BK failure criterion as the basis for judging the interface failure, and the BK failure criterion formula is specifically:

[0027]

[0028] Among them, GequtvC is the equivalent critical energy release rate in the mixed mode, G IC , G IIC , G IIIC They represent the critical energy release rates of type I, type II, and type III crack extension, respectively. I ,G II ,G III It represents the calculated energy release rate of the actual crack propagation directions of type I, type II, and type III near the crack tip, and η represents the mixing ratio.

[0029] Optionally, an extended finite element method is also included. In the loading simulation step, the crack propagation information inside the structural component forming the specified interface is obtained by the extended finite element method, and the design parameters of the structural component in the sub-component analysis model are comprehensively adjusted according to the specified interface parameters and the crack propagation information, so that the specified interface performance and the crack propagation information meet the design requirements.

[0030] Optionally, the designated interface is a screw sleeve-flexible member interface formed between the embedded screw sleeve and the flexible member, or a flexible member-glass fiber reinforced plastic interface formed between the flexible member and the glass fiber reinforced plastic ply. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the cross-sectional structure of a blade root prefabricated part in the current technology;

[0032] Figure 2 for Figure 1 Schematic diagram of the structure shown in FIG.

[0033] Figure 3 A flow chart of a method for designing a blade root prefabricated component of a wind turbine blade in one embodiment of the present invention;

[0034] Figure 4 A schematic diagram of a 2D model of a pre-embedded screw sleeve and a winding flexible component of a blade root of a wind turbine blade in an embodiment of the present invention;

[0035] Figure 5 It is a schematic diagram of a tension-displacement curve of a bilinear cohesion criterion under a uniaxial state of the present invention;

[0036] Figure 6 It is a schematic diagram of a 3D model of a structural component of a blade root prefabricated part of a wind turbine blade in another embodiment of the present invention.

[0037] in, Figure 1 , Figure 2 , Figure 4 and Figure 6 middle:

[0038] 1 embedded screw sleeve; 11 screw sleeve-flexible component interface; 2 first FRP; 3 core material strip; 4 second FRP; 5 flexible component; 6 FRP ply; 12 first contour line; 51 second contour line. DETAILED DESCRIPTION

[0039] Aiming at the technical problem that the existing pre-embedded screw sleeve 1 test in the background technology has poor guidance for the design of the pre-embedded screw sleeve 1, the present invention has conducted in-depth research, and on the basis of a large amount of research, has proposed a technical solution that can guide the design of the blade root prefabricated part. Although the present invention is proposed on the basis of the defects of the pre-embedded screw sleeve 1, the design method provided by the present invention can not only guide the design of the pre-embedded screw sleeve 1, but also guide the design of other structural parts in the blade root prefabricated part except the pre-embedded screw sleeve 1.

[0040] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0041] Please refer to Figure 3 and Figure 4 , Figure 3 A flow chart of a method for designing a blade root prefabricated component of a wind turbine blade in one embodiment of the present invention; Figure 4 The figure is a schematic diagram of a 2D model of a pre-embedded screw sleeve and a winding flexible component of a blade root of a wind turbine blade in one embodiment of the present invention. Figure 4 Where M1 represents the load application position, and P1 and P2 represent the two end points of the displacement fixed constraint.

[0042] The present invention provides a design method for a blade root prefabricated part of a wind turbine blade, the design method comprising:

[0043] Model creation step: create a subcomponent analysis model of the blade root preform, wherein the subcomponent analysis model includes a model for simulating at least two of the embedded screw sleeve 1, the flexible member 5 wound around the embedded screw sleeve 1, the fiberglass ply 6, and the UD bar (uni-directional pultruded composite bar, UD bar in Chinese), and has at least one interface. For example, the subcomponent analysis model can be a model including the embedded screw sleeve 1 and the flexible member 5 wound around the circumference of the embedded bolt 1 sleeve. Usually, the flexible member 5 can be a member that can be wound with glass fiber, yarn, etc. Of course, the subcomponent analysis model can also be a model including the embedded screw sleeve 1, the flexible member 5, the fiberglass ply 6 and the UD bar (not shown). The subcomponent analysis model is not limited to what is shown in this article, and can be a model of two or more components in the blade root preform.

[0044] Loading simulation steps: introducing a cohesive failure unit to the specified interface of the subcomponent analysis model, and applying load-displacement boundary conditions to the subcomponent analysis model to obtain interface parameters that characterize the performance of the specified interface in the current state; wherein the load-displacement boundary conditions can envelop the real load of the blade root in the actual operating condition;

[0045] Adjustment step: adjusting the design parameters of at least one structural member in the sub-component analysis model on the condition that the interface parameters of the specified interface meet the design requirements.

[0046] That is to say, when the interface parameters of the specified interface obtained do not meet the design requirements, the operator can adjust the design parameters of the structural parts in the sub-component analysis model, so as to finally make the interface parameters of the specified interface meet the design requirements. In this step, the design parameters of one structural part can be adjusted, and of course, the design parameters of several structural parts can also be adjusted to achieve that the interface parameters of the specified interface meet the design requirements.

[0047] For example, when the designated interface is the thread sleeve-flexible member 5 interface formed between the embedded thread sleeve 1 and the flexible member 5, the interface parameters of the thread sleeve-flexible member 5 interface can meet the design requirements by adjusting the external thread form of the embedded thread sleeve 1, and of course, by adjusting the winding method of the flexible member 5. Furthermore, when the designated interface is the flexible member 5-glass fiber reinforced plastic interface formed between the flexible member 5 and the glass fiber reinforced plastic layer 6, the parameters of the flexible member 5-glass fiber reinforced plastic interface can also be adjusted by adjusting the external thread form of the embedded thread sleeve 1, or the structure of the glass fiber reinforced plastic layer 6, or the winding method of the flexible member 5.

[0048] Among them, the cohesive zone model (CZM) is a phenomenological model used to simulate the debonding of the two-phase interface or the crack propagation inside the structure. The input parameters of the cohesive zone model include: G IC , G IIC , G IIIC , η, where G IC , G IIC , G IIIC They represent the critical energy release rates of type I, type II, and type III crack extension, respectively. Then they represent the ultimate strength in the direction of crack propagation of type I, type II, and type III, respectively, and η represents the mixing ratio. The input parameters of the cohesive failure unit are obtained by: conducting material-level tests on the specified interface properties through test standards to directly or indirectly fit the input parameters of the cohesive failure unit; wherein the test standards include ASTMD5528, ASTMD7905 or ASTMD6671.

[0049] The above method for obtaining the input parameters of the cohesive failure unit is simple and reliable.

[0050] The cohesion failure unit can use the bilinear cohesion criterion to determine whether the interface fails. Figure 5 The figure shows the typical tension-displacement curve of the bilinear cohesion criterion under the uniaxial state. The horizontal axis is the opening displacement δ and the vertical axis is the stress σ. It describes the phenomenon that the stress of the bonding layer increases first and then decreases with the opening displacement when subjected to external load. Before the stress peak, the material is in the linear elastic stage. After reaching the ultimate strength, damage begins to initiate and the stiffness softens. After that, the stress value decreases with the increase of displacement, the material bearing capacity decreases, and the damage gradually accumulates. When the final failure displacement is reached, the stress decreases to zero, the crack is fully extended, and the interface cracks and fails. The area enclosed by the tension-displacement curve and the coordinate axis is the fracture toughness of the interface, which represents the energy dissipation of the material crack surface opening process, that is, the critical energy release rate. The tension-displacement curve of the cohesion failure unit can be determined by the three parameters of the elastic section stiffness, ultimate strength and fracture toughness Gc (or final failure displacement).

[0051] Cohesive failure elements with bilinear cohesion criterion have a relatively fast simulation speed.

[0052] Of course, in fracture mechanics, cracks are divided into three types according to their stress and crack propagation path, namely type I, type II, and type III cracks. Accordingly, the cohesive failure unit of the present invention uses the secondary nominal stress criterion as the basis for judging interface failure. The secondary nominal stress criterion formula is specifically:

[0053]

[0054] Among them, σ n ,σ s ,σ t Represents the stress components under the three crack extension directions of type I, type II, and type III respectively They represent the ultimate strength in the direction of crack extension of type I, type II, and type III respectively. The maximum nominal stress (strain) or secondary nominal strain can also be used as the damage criterion according to actual needs.

[0055] The simulation accuracy of the cohesive failure unit with the quadratic nominal stress criterion is relatively high, which is close to the changes in the interface performance of the components in actual work, and the simulation reliability is relatively high.

[0056] In another specific embodiment, the cohesion failure unit can also use the BK failure criterion as a basis for judging interface failure. The BK failure criterion formula is specifically:

[0057]

[0058] Among them, GequtvC is the equivalent critical energy release rate in the mixed mode, G IC , G IIC , G IIIC Respectively represent the critical energy release rate of type I, type II, and type III crack growth, usually G IIIC =G IIc ; G I ,G II ,G III It represents the calculated energy release rate of the actual type I, type II, and type III crack propagation directions near the crack tip. η represents the mixing ratio, which is an intrinsic parameter of the material and can be obtained through test fitting.

[0059] The simulation accuracy of this judgment criterion is relatively high.

[0060] Of course, in another specific embodiment, the cohesive failure unit may also select other damage evolution criteria as needed, such as the Power-law criterion or the displacement-based failure criterion to determine the interface failure criterion.

[0061] The interface failure criteria for the cohesive failure unit are different, and the parameters that need to be input may be slightly different. The input parameters can be obtained based on material properties or material tests or fitting of the test experiments.

[0062] In the present invention, a sub-component analysis model located at the blade root prefabricated part is pre-established, and after a cohesive failure unit is introduced into a designated interface, a load-displacement boundary condition is applied to the sub-component analysis model to obtain interface parameters characterizing the performance of the designated interface in the current state, and whether the current state of the designated interface meets the design requirements is determined based on the interface parameters. If the design requirements are not met, the design parameters of at least one structural component in the prefabricated part are adjusted, so that the designated interface parameters finally meet the design requirements.

[0063] The present invention can obtain the rules between the specified interface strengths through the cohesive failure unit, which plays a guiding role in optimizing the design parameters of each structural member in the prefabricated part, and further can also obtain better working performance of the blade root. Moreover, the method is simple and the manpower and material costs are low.

[0064] In the above embodiments, the cohesive failure unit is a cohesive unit with a predetermined thickness at the interface (common node or binding constraint), or the cohesive failure unit is a cohesive unit with zero thickness at the interface, or the cohesive failure unit is the cohesive contact property of the specified interface, which can be reasonably set according to the simulated product to meet the simulation requirements.

[0065] The subcomponent analysis model in the present invention is a finite element model. In the loading simulation step, at least one of the mesh density, analysis step length, and viscosity regularization coefficient of the finite element model is adjusted to balance the calculation iteration convergence and calculation efficiency.

[0066] The load in the load-displacement boundary condition in the present invention includes at least one of a displacement load or a force load. For example, taking the load as a displacement load, that is, a loading-displacement boundary condition, the interface parameter characterizing the interface performance can be the peak support reaction force at the loading point, and the peak support reaction force can characterize the interface strength.

[0067] In one example, the subcomponent analysis model is a two-dimensional diagram, and the simulation speed can be improved by using a small number of grids in the two-dimensional diagram compared to the three-dimensional structural model. Figure 4 As shown, the sub-component analysis model includes a first contour line 12 and a second contour line 51. The first contour line 12 is the hole wall line of the embedded screw sleeve 1, and the second contour line 51 is the outer wall line of the flexible member 5. In the loading simulation step, the load can be applied to the midpoint position M of the second contour line 51 through multi-point coupling constraints, and the P1-P2 interval of the first contour line 12 is in a fixed constraint state. Of course, the sub-component analysis model can also be a three-dimensional graph, such as Figure 6 shown.

[0068] In the above embodiments, the external thread form of the embedded screw sleeve 1 includes one or more of the profile type, amplitude, wavelength, etc. For example, the profile type can be a close pitch thread, a circular arc segment or a multi-segment line chamfer structure.

[0069] In an embodiment of the present invention, the design method of the blade root preform of the wind turbine blade may further include an extended finite element method. In the loading simulation step, the crack propagation information inside the structural component forming the specified interface is obtained by the extended finite element method, and the design parameters of the connector in the sub-component analysis model are comprehensively adjusted according to the interface parameters of the specified interface and the crack propagation information, so that the specified interface performance and the crack propagation information meet the design requirements.

[0070] For better understanding, taking the designated interface as the screw sleeve-flexible part 5 interface 11 as an example, in the loading simulation step, the crack propagation information inside the flexible part 5 is also obtained by the extended finite element method, and the external thread parameters of the embedded screw sleeve 1 are comprehensively adjusted according to the interface parameters of the screw sleeve-flexible part 5 interface 11 and the crack propagation information, so that the interface performance and crack propagation information of the screw sleeve-flexible part 5 interface 11 meet the design requirements.

[0071] This embodiment combines the cohesive failure element and the extended finite element method, and the simulation takes more factors into consideration, so the authenticity of the simulated structure is relatively high.

[0072] In an embodiment of the present invention, the designated interface may be one interface or two or more interfaces. For example, the interface parameters of the screw sleeve-flexible part 5 interface and the interface parameters of the flexible part 5-glass fiber reinforced plastic interface are comprehensively considered to adjust the external thread parameters of the embedded screw sleeve 1 so that the interface performance of the screw sleeve-flexible part 5 and the interface performance of the flexible part 5-glass fiber reinforced plastic meet the design requirements.

[0073] Please refer again Figure 3 Based on the above disclosure, the present invention provides a specific implementation method of a design method for a blade root prefabricated part of a wind turbine blade:

[0074] S1. Create a subcomponent analysis model of a blade root preform, wherein the subcomponent analysis model includes a model for simulating at least two of the embedded screw sleeve 1, the flexible member 5 wound around the embedded screw sleeve 1, the fiberglass ply 6, and the UD strip;

[0075] S2. Select appropriate test standards to conduct material-level tests on specified interface properties to obtain the input parameters required for the cohesive failure unit;

[0076] S3, introducing a cohesive failure unit into a designated interface of the subcomponent analysis model, and inputting the input parameters obtained in step S2;

[0077] S4, applying load-displacement boundary conditions to the subcomponent analysis model, balancing the computational iteration convergence and computational efficiency by adjusting simulation settings such as the mesh density, analysis step length, and viscosity regularization coefficient of the subcomponent analysis model, so as to obtain interface parameters characterizing the specified interface performance in the current state;

[0078] According to the requirements of industry standards such as DNV-0376, appropriate load-displacement boundary conditions can be applied to the sub-component analysis model to try to envelop the actual load of the blade root in actual operation, so that the selected simulation conditions can conservatively predict the interface strength of the specified interface.

[0079] S5. Adjust design parameters of at least one structural component in the subcomponent analysis model according to the obtained interface parameters, so that the interface parameters of the specified interface performance meet the design requirements.

[0080] The adjustment of the design parameters of the structural parts in the sub-component analysis model in step S5 can be manually adjusted by the designer or automatically adjusted by the simulation program.

[0081] The above is a detailed introduction to the design method of the blade root preform of a wind turbine blade provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for designing a blade root prefabricated part of a wind turbine blade, characterized in that: The design method comprises: Model creation step: creating a subcomponent analysis model of the blade root preform, wherein the subcomponent analysis model includes a model for simulating at least two of the embedded screw sleeve, a flexible member wound around the circumference of the embedded screw sleeve, a fiberglass ply, and a UD strip; Loading simulation step: introducing a cohesive failure unit to a designated interface of the subcomponent analysis model, and applying a load-displacement boundary condition to the subcomponent analysis model to obtain interface parameters characterizing the performance of the designated interface in a current state; wherein the load-displacement boundary condition can envelop the real load of the blade root in an actual operating condition; Adjustment step: adjusting the design parameters of at least one structural component in the sub-component analysis model on the condition that the interface parameters of the designated interface meet the design requirements.

2. The method for designing a blade root prefabricated part of a wind turbine blade according to claim 1, characterized in that: The input parameters of the cohesion failure unit are obtained by: conducting material-level tests on the specified interface performance according to the test standard to directly or indirectly fit and obtain the input parameters of the cohesion failure unit; The input parameters of the cohesive failure unit include: G IC , G IIC , G IIIC , η, where G IC , G IIC , G IIIC They represent the critical energy release rates of type I, type II, and type III crack extension, respectively. They represent the ultimate strength in type I, type II, and type III expansion directions respectively, and η represents the mixing ratio.

3. The method for designing a blade root prefabricated part of a wind turbine blade according to claim 2, characterized in that: The test standards include ASTM D5528, ASTM D7905 or ASTM D6671.

4. The method for designing a blade root prefabricated part of a wind turbine blade according to claim 1, characterized in that: The cohesive failure unit is a cohesive unit having a predetermined thickness at the designated interface. Alternatively, the cohesive failure unit is a cohesive unit with zero thickness at the specified interface, Alternatively, the cohesive failure unit is a cohesive contact property of the designated interface.

5. The method for designing a blade root prefabricated part of a wind turbine blade according to claim 1, characterized in that: The subcomponent analysis model is a finite element model. In the loading simulation step, at least one of the mesh density, analysis step length, and viscosity regularization coefficient of the finite element model is adjusted to balance the computational iteration convergence and computational efficiency.

6. The method for designing a blade root prefabricated part of a wind turbine blade according to claim 1, characterized in that: The load in the load-displacement boundary condition includes at least one of a displacement load or a force load.

7. The method for designing a blade root prefabricated part of a wind turbine blade according to claim 1, characterized in that: The design parameters of the structural parts in the sub-component analysis model include one or more of the outer contour parameters of the embedded screw sleeve, the winding method of the flexible part, the FRP ply structure shape, or the UD strip structure shape.

8. The method for designing a blade root prefabricated part of a wind turbine blade according to claim 1, characterized in that: The subcomponent analysis model is a two-dimensional graph; Alternatively, the subcomponent analysis model is a three-dimensional structure diagram.

9. The method for designing a blade root prefabricated part of a wind turbine blade according to claim 1, characterized in that: The cohesion failure unit uses the quadratic nominal stress criterion as the basis for judging the interface failure. The quadratic nominal stress criterion formula is specifically: Among them, σ n ,σ s ,σ t They represent the stress components under the three crack extension directions of type I, type II, and type III, respectively. They represent the ultimate strength in the crack extension directions of type I, type II, and type III respectively; Alternatively, the cohesion failure unit uses the BK failure criterion as the basis for judging the interface failure, and the BK failure criterion formula is specifically: Among them, G equtvC is the equivalent critical energy release rate in the mixed mode, G IC , G IIC , G IIIC They represent the critical energy release rates of type I, type II, and type III crack extension, respectively. I ,G II ,G III It represents the calculated energy release rate of the actual type I, type II, and type III crack extension near the crack tip, and η represents the mixing ratio.

10. The method for designing a blade root prefabricated part of a wind turbine blade according to claim 1, characterized in that: It also includes an extended finite element method. In the loading simulation step, the crack propagation information inside the structural component forming the specified interface is obtained by the extended finite element method, and the design parameters of the structural component in the sub-component analysis model are comprehensively adjusted according to the specified interface parameters and the crack propagation information, so that the specified interface performance and the crack propagation information meet the design requirements.

11. The method for designing a blade root prefabricated part of a wind turbine blade according to any one of claims 1 to 9, characterized in that: The designated interface is a screw sleeve-flexible member interface formed between the embedded screw sleeve and the flexible member, or a flexible member-glass fiber reinforced plastic interface formed between the flexible member and the glass fiber reinforced plastic layer.

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