A wind power blade main beam layered damage failure analysis method based on body shell coupling

Abstract

The application provides a wind turbine blade main beam layered damage failure analysis method based on body-shell coupling, comprising the following steps: establishing a full-size blade geometric model and a full-size blade shell finite element analysis model; selecting the full-size blade from the blade root joint circle to the 1 / 3 blade length section as the shell analysis model; embedding a prefabricated layered defect into the full-size blade main beam region by using a body-shell coupling method to obtain a body-shell coupling model for the blade main beam damage failure analysis; using a blade root fixed constraint, applying an equivalent fatigue load on the end of the shell analysis model by using a multi-point constraint method, extracting the out-of-plane displacement of the center points on the upper surface and the lower surface of the sub-plate, and the layered expansion failure history with the load action time; and conducting layered failure research on the full-size blade layered damage. The application can solve the problem that there is no effective analysis method for the layered failure mode and expansion path of the wind turbine blade main beam.

Description

Technical Field

[0001] This invention relates to wind turbine blade main beam damage identification technology, specifically to a method for analyzing layered damage failure of wind turbine blade main beams based on body-shell coupling. Background Technology

[0002] With the continuous growth of global energy demand and the increasing awareness of environmental protection, wind energy, as a clean, renewable, and pollution-free energy source, has received widespread attention. Wind power generation, as one of the main methods of wind energy utilization, has seen its technological development and application scale continuously expand. The performance, reliability, and safety of wind turbine generators directly affect the operating efficiency and economic benefits of the entire wind farm. However, wind turbine generators are exposed to a complex and ever-changing natural environment for extended periods, enduring various loads, especially the blades, which directly face the challenges of wind and other environmental factors. Therefore, predicting the delamination failure of the main beam of wind turbine blades is particularly important.

[0003] Wind turbine blades are one of the core components of wind turbine generators, with complex structures composed of various materials. The blade main spars, as the primary load-bearing component, have a decisive impact on the blade's performance and lifespan due to their structural design and material selection. Blade main spars are typically made of composite materials, which offer advantages such as high strength, high modulus, and light weight. However, they also possess some potential defects, such as delamination, insufficient bonding, and wrinkles. These defects accumulate and develop under long-term loads, eventually leading to damage and failure of the blade main spars structure. Delamination failure is one of the common failure modes of wind turbine blade main spars. It is mainly caused by insufficient interlayer bonding strength of the composite material or excessive shear load. Delamination failure reduces the overall stiffness and strength of the blade main spars structure, thus affecting the blade's vibration characteristics and aerodynamic performance. In severe cases, delamination failure can even lead to blade breakage or detachment, posing a serious threat to the normal operation and safety of the wind turbine generator. Therefore, to effectively predict delamination failure of wind turbine blade main spars, this invention proposes a delamination damage failure analysis method for wind turbine blade main spars based on body-shell coupling. Summary of the Invention

[0004] To address the lack of effective analytical methods for the layered failure modes and propagation paths of wind turbine blade main beams in existing research, this invention proposes a layered damage failure analysis method for wind turbine blade main beams based on body-shell coupling.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for analyzing layered damage failure of the main beam of a wind turbine blade based on body-shell coupling, the method comprising the following steps:

[0007] Step 1: Perform geometric modeling on the shape of the blade shell coupling structure to be analyzed. The aerodynamic centers of all airfoil sections of the full-size blade geometric model are located on the same straight line, and all aerodynamic centers are located at 1 / 3 of the blade chord length. Perform three-dimensional coordinate transformation on the blade airfoil data according to the aerodynamic shape.

[0008] Step 2: Create a finite element analysis model of the full-size blade shell based on the full-size blade geometry model;

[0009] Step 3: Based on the finite element analysis model of the full-size blade shell, the full-size blade from the root pitch circle to 1 / 3 of the blade length is selected as the shell analysis model, and the ply thickness of the main beam increases from 0 to the maximum thickness; a prefabricated delaminated body model is created based on the laminated plate theory and cohesion model, and the prefabricated delaminated defects are embedded into the main beam region of the full-size blade using the body-shell coupling method to obtain the body-shell coupling model for damage and failure analysis of the blade main beam;

[0010] Step 4: Based on the shell-body coupling model, using leaf root fixed constraints, an equivalent fatigue load is applied to the end of the shell analysis model using a multi-point constraint method. The out-of-plane displacements of the center points of the upper and lower surfaces of the sub-plates are extracted, as well as the layered expansion failure history with the load application time. The distribution trends of the out-of-plane displacements of the upper and lower sub-plates and the damage factor cloud maps for different load application times are obtained respectively.

[0011] Step 5: Based on the distribution trend of the out-of-plane displacement of the upper and lower sub-plates, determine whether the failure mode of delamination damage is local buckling, global buckling, or mixed buckling;

[0012] Step 6: Based on the damage factor cloud map of different load application times, analyze the propagation path of stratified failure under continuous loading.

[0013] Furthermore, in step 1, the process of performing three-dimensional coordinate transformation on the blade airfoil data based on the aerodynamic shape includes the following steps:

[0014] Retrieve the original two-dimensional plane coordinates (X,Y) of the airfoil and solve for the two-dimensional coordinates (X,Y) of the airfoil with the aerodynamic center as the origin and the line connecting the leading and trailing edges of the airfoil as the axis. 1, Y1):

[0015] (X1,Y1)=(X,Y-X0,Y0)

[0016] In the formula, (X0, Y0) are the coordinates of the aerodynamic center; the coordinates of each blade element are calculated in conjunction with the chord length:

[0017] (X2,Y2)=C(X1,Y1)

[0018] In the formula, C is the chord length of the cross section;

[0019] Rotating the leaf element yields the actual spatial coordinates:

[0020]

[0021] In the formula, θ is the twist angle, and r is the position of the airfoil section; combining the two formulas above, we get:

[0022]

[0023] Step 2 further includes:

[0024] The full-size blade geometry model was imported into the commercial finite element software ABAQUS as a STEP file. Based on the structural layout, ply design, and material selection, the chordal and spanwise structural partitions and ply planning were performed to create a full-size blade shell finite element analysis model.

[0025] Furthermore, in step 3, a full-size blade from the root node circle to 1 / 3 of the blade length is selected as the shell analysis model, and layering defects are preset at different main beam thickness positions in the blade segment;

[0026] In the blade segment geometric model, the main beam partition adopts a design of equal width but unequal thickness, and the inner width of the double web edge strip is used as the width of the main beam layer failure model. The blade segment mesh with the pre-embedded layer size is divided into three regions: the first region is the blade shell part, using four-node S4R elements; the second region is the main beam region, using eight-node continuous elements SC8R; the third region is the pre-embedded layer region and the layer perimeter extension region, using three-dimensional cohesive elements COH3D8. The SC4R elements in the first region and the SC8R elements in the second region are connected by a body-shell coupling method, and contact constraints are set to avoid mutual penetration between elements.

[0027] Furthermore, in step 3, the process of connecting the SC4R element in the first region and the SC8R element in the second region using a body-shell coupling method includes the following steps:

[0028] An internal distributed coupling constraint set is created using reference nodes at the shell edge and coupled nodes on the solid surface to ensure compatibility of SC4R and SC8R elements in terms of displacement and stress balance at the connection point; specifically, the nodal displacement of the shell element at the connection point is equal to the displacement of the corresponding node in the thickness direction of the solid element.

[0029]

[0030] In the formula, w i Based on multi-point constraint type and node location, Let u be the displacement of the i-th multi-point constraint node, n be the total number of multi-point constraint nodes, and u be the displacement of the i-th multi-point constraint node. xFor the displacement of the solid node; the rotational degrees of freedom of the shell element nodes at the connection are consistent with those of the nodes in the thickness direction of the solid element. It is assumed that the nodes on the solid remain on a straight line, represented by the normalized direction N of the undeformed configuration and the normalized direction m of the deformed configuration. The rotation of the nodes is represented by the finite rotation vector Φ, and the rotation constraint formula is:

[0031] A·N=m

[0032] in, It is a skew-symmetric matrix of Φ.

[0033] Step 4 further includes:

[0034] Based on the body-shell coupling model, a fixed constraint is set at the root of the blade to restrict all degrees of freedom (U1, U2, U3, UR1, UR2, UR3), where U1, U2, and U3 are the translational degrees of freedom along the x, y, and z coordinate axes, respectively, and UR1, UR2, and UR3 are the rotational degrees of freedom along the x, y, and z coordinate axes, respectively, so that the degrees of freedom of each node at the root section in each direction is 0.

[0035] MPC multi-point constraints are set at the end of the analysis model to couple the motion of the main beam nodes to a reference node, which is used to load the equivalent fatigue load. Different load coefficients are selected for loading.

[0036] The buckling modes of the main beam are distinguished by the center nodes on the upper and lower sub-plate surfaces where the layers are located. A set of nodes is defined at the center point L on the upper surface of the sub-plate and the center point U on the lower surface of the sub-plate, and the out-of-plane displacements of each key point in the set of nodes are extracted.

[0037] Step 5 further includes:

[0038] When the displacement paths of the two nodes are the same and the upper and lower subplates move in the same direction, the delamination gap closes, and the failure mode of delamination damage is determined to be global buckling. When the lower subplate node where the delamination is located remains horizontally stationary and the center node of the upper subplate moves upward, causing the delamination gap to open, the failure mode of delamination damage is determined to be local buckling. When the center nodes of both the upper and lower subplates move away from the initial position to different degrees and the delamination gap is open, the failure mode of delamination damage is determined to be mixed buckling mode.

[0039] Step 6 further includes:

[0040] Extract the damage factors from the layered interface, make the output step and the loading step consistent, and draw the damage factor cloud map;

[0041] At different load application time points, observe and record the changes in the damage factor cloud map, analyze the distribution and changing trend of damage factors in the damage factor cloud map, and determine the propagation path of stratified failure based on the accumulation and expansion of damage factors in the damage factor cloud map.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0043] The method for analyzing the delamination damage failure of the main beam of wind turbine blades based on body-shell coupling proposed in this invention can systematically analyze and judge the delamination propagation failure process of wind turbine blade models containing prefabricated delamination defects under equivalent fatigue loads. This provides a scientific basis for the structural design and maintenance of wind turbine blades and is of great significance for reducing the operation and maintenance costs of wind turbine blades and ensuring the healthy and stable operation of wind turbine blades. Attached Figure Description

[0044] Figure 1 This is a flowchart of the layered damage failure analysis method for the main beam of a wind turbine blade based on body-shell coupling, according to an embodiment of the present invention.

[0045] Figure 2 A schematic diagram of layered damage on the main beam of a wind turbine blade;

[0046] Figure 3 This is a diagram showing the dimensions of the hierarchical analysis model.

[0047] Figure 4 A schematic diagram of a full-size blade shell model and a volumetric model of layered damage;

[0048] Figure 5 This is a schematic diagram of the shell coupling segment;

[0049] Figure 6 This is an equivalent fatigue load distribution diagram;

[0050] Figure 7 The diagram shows the equivalent fatigue load applied to the leaf segment.

[0051] Figure 8 This is a schematic diagram of out-of-plane displacement.

[0052] Figure 9 This is a schematic diagram for determining failure modes;

[0053] Figure 10 This is a cloud map of damage factors. Detailed Implementation

[0054] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0055] This invention discloses a method for analyzing layered damage failure of the main beam of a wind turbine blade based on body-shell coupling (the specific process is as follows). Figure 1 As shown), the specific steps include:

[0056] Step 1: Using SolidWorks software, geometrically model the shape of the blade shell coupling structure to be analyzed. Based on the aerodynamic shape, perform a three-dimensional coordinate transformation on the blade airfoil data to obtain a solid model of the pre-fabricated layered defects and a full-size blade shell model; specifically including:

[0057] During geometric modeling, a blade geometric model is created in SolidWorks software. The aerodynamic centers of all airfoil sections of the blade geometric model are located on the same straight line, and these aerodynamic centers are located at 1 / 3 of the blade chord length. The blade airfoil data is then transformed into three-dimensional coordinates based on the aerodynamic shape.

[0058] Retrieve the original two-dimensional plane coordinates (X,Y) of the airfoil and solve for the two-dimensional coordinates (X,Y) of the airfoil with the aerodynamic center as the origin and the line connecting the leading and trailing edges of the airfoil as the axis. 1, Y1). Let the aerodynamic center coordinates be (X0, Y0), C be the chord length of the section, θ be the twist angle, and r be the position of the airfoil section.

[0059] (X1,Y1)=(X,Y-X0,Y0)

[0060] Calculate the coordinates of each leaf element based on the chord length:

[0061] (X2,Y2)=C(X1,Y2)

[0062] Rotating the leaf element yields the actual spatial coordinates:

[0063]

[0064] Combining the two formulas above, we get:

[0065]

[0066] Step 2: Based on the full-size blade geometry model, create a full-size blade shell finite element analysis model; specifically including:

[0067] The full-size blade geometry model was imported into the commercial finite element software ABAQUS as a STEP file. Based on the structural layout, ply design, and material selection, the chordal and spanwise structural partitions and ply planning were performed to create a full-size blade shell finite element analysis model.

[0068] Step 3: Select the full-size blade, from the root pitch circle to 1 / 3 of the blade length, as the shell analysis model. At this point, the main beam ply thickness rapidly increases from 0 to its maximum thickness. Based on laminated plate theory and cohesion model, a prefabricated layered body model is created. A body-shell coupling method is used to embed the prefabricated layers into the main beam region of the full-size blade, thus realizing a body-shell coupling model for damage and failure analysis of the blade's main beam. Specifically, this includes:

[0069] In this embodiment, a full-size blade from the root node circle to 1 / 3 of the blade length is selected as the shell analysis model (e.g., ...). Figure 2 As shown), layered defects are preset at different main beam thickness locations on the leaf segment, and the layered analysis model size is 80*60mm (as shown). Figure 3 (As shown). A prefabricated layered body model was created based on laminate theory and cohesion model (e.g., Figure 4 (As shown).

[0070] In this embodiment, the main beam in the leaf segment geometric model adopts a design of equal width but unequal thickness. The main beam with the same thickness has a span of about 1600mm and a width of 400mm. The width of the inner side of the double web edge strip is 130mm as the width of the main beam layered failure model.

[0071] The pre-embedded, layered blade segment mesh was divided into three regions. Region 1, the blade shell portion, used four-node S4R elements suitable for thick shell elements, with a mesh element size of 50mm × 50mm, resulting in approximately 35,000 shell elements per segment. Region 2, the main beam region, used eight-node continuous elements SC8R, capable of representing triaxial stress states, with a mesh size of 5mm × 5mm. Region 3, the pre-embedded layered region and its surrounding extension region, used three-dimensional cohesive elements COH3D8, with a mesh size of 5mm × 5mm. The analysis model comprised a total of 754 cohesive elements.

[0072] Among them, the SC4R elements in region one and the SC8R elements in the main beam region of region two are connected by a body-shell coupling method (e.g., Figure 5 (as shown), and contact constraints are set to prevent mutual penetration between units.

[0073] Preferably, in the body-shell coupling method, an internal distributed coupling constraint set is created through reference nodes at the shell edge and coupling nodes on the solid surface to achieve compatibility of displacement and stress balance at the connection between the two element types. The nodal displacement of the shell element at the connection is equal to the displacement of the corresponding node in the thickness direction of the solid element, as shown in the equation:

[0074]

[0075] Among them, w i Based on multi-point constraint type and node location, Let u be the displacement of the i-th multi-point constraint node, n be the total number of multi-point constraint nodes, and u be the displacement of the i-th multi-point constraint node. x This represents the displacement of the entity nodes.

[0076] Simultaneously, the rotational degrees of freedom of the shell element nodes at the connection points must be consistent with those of the nodes in the thickness direction of the solid element. Assuming that the nodes on the solid remain on a straight line, this straight line is represented by the normalized direction N of the undeformed configuration and the normalized direction m of the deformed configuration. The rotation of the nodes is represented by the finite rotation vector Φ, and the rotation constraint formula is:

[0077] A·N=m

[0078] in, It is a skew-symmetric matrix of Φ.

[0079] Step 4: Based on the shell-body coupling model, using leaf root fixed constraints, apply equivalent fatigue loads at the ends of the analysis model using a multi-point constraint method. Extract the out-of-plane displacements of the center points of the upper and lower surfaces of the sub-plates of the sub-model containing pre-fabricated delamination defects, as well as the delamination propagation failure history over time; specifically including:

[0080] Based on the shell-body coupled model, fixed constraints are set at the blade root to restrict all degrees of freedom (U1, U2, U3, UR1, UR2, UR3), where U1, U2, and U3 are translational degrees of freedom along the x, y, and z axes, respectively, and UR1, UR2, and UR3 are rotational degrees of freedom along the x, y, and z axes, respectively, making the degrees of freedom of each node at the root section zero in all directions. MPC multi-point constraints are set at the ends of the analysis model to couple the motion of the main beam nodes to a reference node, which is used to apply equivalent fatigue loads (such as...). Figure 6 and Figure 7 As shown in the figure, different load factors can be selected for loading.

[0081] The buckling mode of the main beam is distinguished by the center nodes of the upper and lower sub-slab surfaces where the layers are located. L and U represent the center nodes of the upper and lower sub-slab surfaces, respectively. Node sets are defined at the center point L on the upper surface of the sub-slab and the center point U on the lower surface of the sub-slab. Output requests are set in Abaqus to extract the out-of-plane displacements of these key points (e.g., ...). Figure 8 As shown in the figure, and the stratified expansion failure process with the duration of load application.

[0082] Step 5: Based on the distribution trend of the out-of-plane displacement of the upper and lower sub-plates, determine whether the failure mode of delamination damage is local buckling, global buckling, or mixed buckling; the specific determination process is as follows:

[0083] When the displacement paths of the two nodes are the same and the upper and lower sub-plates move in the same direction, the delamination gap closes, which is global buckling. When the lower sub-plate node containing the delamination remains horizontally stationary while the center node of the upper sub-plate moves upward, causing the delamination gap to open, the buckling mode in this state is local buckling. The mixed buckling mode occurs when the center nodes of both the upper and lower sub-plates move away from their initial positions to varying degrees, while the delamination gap remains open (e.g., ...). Figure 9 (As shown).

[0084] Step 6: Based on the damage factor cloud maps of different load application times, determine the propagation path of delamination failure with continuous loading, thereby realizing the delamination failure study of full-size blade delamination damage based on body-shell coupling; the specific analysis process is as follows:

[0085] Extract the damage factors from the layered interface, ensuring consistency between the output step and the loading step, and use Abaqus post-processing to plot the damage factor contour map (e.g., Figure 10 (As shown); At different load application time points, observe and record the changes in the damage factor cloud map, analyze the distribution and changing trend of damage factors in the damage factor cloud map, especially the damage degree of the layered interface, and determine the propagation path of layered failure based on the accumulation and expansion of damage factors in the cloud map.

[0086] This invention addresses the lack of effective analysis methods for the layered failure modes and propagation paths of wind turbine blades, clarifies the evolution mechanism of layered failure in wind turbine blades, and is of great significance for reducing the operation and maintenance costs of wind turbine blades and ensuring their healthy and stable operation.

[0087] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0088] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, produce instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0089] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0090] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment, causing a series of operational steps to be executed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that run on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0091] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0092] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for analyzing the layered damage failure of a wind turbine blade spar based on body-shell coupling, characterized in that, The method includes the following steps: Step 1: Perform geometric modeling on the shape of the blade shell coupling structure to be analyzed. The aerodynamic centers of all airfoil sections of the full-size blade geometric model are located on the same straight line, and all aerodynamic centers are located at 1 / 3 of the blade chord length. Perform three-dimensional coordinate transformation on the blade airfoil data according to the aerodynamic shape. Step 2: Create a finite element analysis model of the full-size blade shell based on the full-size blade geometry model; Step 3: Based on the finite element analysis model of the full-size blade shell, the full-size blade from the root pitch circle to 1 / 3 of the blade length is selected as the shell analysis model, and the ply thickness of the main beam increases from 0 to the maximum thickness; a prefabricated delaminated body model is created based on the laminated plate theory and cohesion model, and the prefabricated delaminated defects are embedded into the main beam region of the full-size blade using the body-shell coupling method to obtain the body-shell coupling model for damage and failure analysis of the blade main beam; Step 4: Based on the shell-body coupling model, using leaf root fixed constraints, an equivalent fatigue load is applied to the end of the shell analysis model using a multi-point constraint method. The out-of-plane displacements of the center points of the upper and lower surfaces of the sub-plates are extracted, as well as the layered expansion failure history with the load application time. The distribution trends of the out-of-plane displacements of the upper and lower sub-plates and the damage factor cloud maps for different load application times are obtained respectively. Step 5: Based on the distribution trend of the out-of-plane displacement of the upper and lower sub-plates, determine whether the failure mode of delamination damage is local buckling, global buckling, or mixed buckling; Step 6: Based on the damage factor cloud map of different load application times, analyze the propagation path of stratified failure under continuous loading.

2. The method of claim 1, wherein, Step 1, the process of performing three-dimensional coordinate transformation on the blade airfoil data based on the aerodynamic shape, includes the following steps: The original two-dimensional coordinate (X, Y) of the blade element airfoil is called, and the two-dimensional coordinate (X, Y) of the airfoil with the aerodynamic center as the origin and the connecting line of the leading edge and the trailing edge as the axis is solved 1, Y1): (X1,Y1)=(X,Y-X0,Y0) In the formula, (X0,Y0) are the coordinates of the aerodynamic center; Calculate the coordinates of each leaf element based on the chord length: (X2,Y2)=C(X1,Y1) In the formula, C is the chord length of the cross section; Rotating the leaf element yields the actual spatial coordinates: In the formula, θ is the twist angle, and r is the position of the airfoil section; Combining the two formulas above, we get:

3. The method of claim 1, wherein, Step 2 further includes: The full-size blade geometry model was imported into the commercial finite element software ABAQUS as a STEP file. Based on the structural layout, ply design, and material selection, the chordal and spanwise structural partitions and ply planning were performed to create a full-size blade shell finite element analysis model.

4. The method of claim 1, wherein, In step 3, a full-size blade from the root node circle to 1 / 3 of the blade length is selected as the shell analysis model, and layering defects are preset at different main beam thicknesses in the blade segment; In the blade segment geometric model, the main beam partition adopts a design of equal width but unequal thickness, and the inner width of the double web edge strip is used as the width of the main beam layer failure model. The blade segment mesh with the pre-embedded layer size is divided into three regions: the first region is the blade shell part, using four-node S4R elements; the second region is the main beam region, using eight-node continuous elements SC8R; the third region is the pre-embedded layer region and the layer perimeter extension region, using three-dimensional cohesive elements COH3D8. The SC4R elements in the first region and the SC8R elements in the second region are connected by a body-shell coupling method, and contact constraints are set to avoid mutual penetration between elements.

5. The method of claim 4, wherein, Step 3, the process of connecting the SC4R element in the first region and the SC8R element in the second region using a body-shell coupling method includes the following steps: An internal distributed coupling constraint set is created using reference nodes at the shell edge and coupled nodes on the solid surface to ensure compatibility of SC4R and SC8R elements in terms of displacement and stress balance at the connection point; specifically, the nodal displacement of the shell element at the connection point is equal to the displacement of the corresponding node in the thickness direction of the solid element. where w i is based on the type of multi-point constraint and the position of the node, is the displacement of the i-th multi-point constraint node, n is the total number of multi-point constraint nodes, u x is the displacement of the solid node; the rotational freedom of the joint shell element node is consistent with the node in the thickness direction of the solid element. It is assumed that the nodes on the solid remain in a straight line, which is represented by the normalized direction N in the undeformed configuration and the normalized direction m in the deformed configuration. The rotation of the node is represented by the finite rotation vector Φ, and the rotational constraint formula is: A·N=m wherein is a skew-symmetric matrix form of Φ.

6. The method of claim 1, wherein, Step 4 further includes: Based on the body-shell coupling model, a fixed constraint is set at the root of the blade to restrict all degrees of freedom (U1, U2, U3, UR1, UR2, UR3), where U1, U2, and U3 are the translational degrees of freedom along the x, y, and z coordinate axes, respectively, and UR1, UR2, and UR3 are the rotational degrees of freedom along the x, y, and z coordinate axes, respectively, so that the degrees of freedom of each node at the root section in each direction is 0. MPC multi-point constraints are set at the end of the analysis model to couple the motion of the main beam nodes to a reference node, which is used to load the equivalent fatigue load. Different load coefficients are selected for loading. The buckling modes of the main beam are distinguished by the center nodes on the upper and lower sub-plate surfaces where the layers are located. A set of nodes is defined at the center point L on the upper surface of the sub-plate and the center point U on the lower surface of the sub-plate, and the out-of-plane displacements of each key point in the set of nodes are extracted.

7. The method of claim 1, wherein, Step 5 further includes: When the displacement paths of the two nodes are the same and the upper and lower subplates move in the same direction, the delamination gap closes, and the failure mode of delamination damage is determined to be global buckling. When the lower subplate node where the delamination is located remains horizontally stationary and the center node of the upper subplate moves upward, causing the delamination gap to open, the failure mode of delamination damage is determined to be local buckling. When the center nodes of both the upper and lower subplates move away from the initial position to different degrees and the delamination gap is open, the failure mode of delamination damage is determined to be mixed buckling mode.

8. The method for analyzing layered damage failure of wind turbine blade main beam based on body-shell coupling according to claim 1, characterized in that, Step 6 further includes: Extract the damage factors from the layered interface, make the output step and the loading step consistent, and draw the damage factor cloud map; At different load application time points, observe and record the changes in the damage factor cloud map, analyze the distribution and changing trend of the damage factors, and determine the propagation path of stratified failure based on the accumulation and expansion of the damage factors in the damage factor cloud map.

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