A wind turbine hub rapid force analysis method

Abstract

The present application belongs to the field of wind power generation equipment structure design and finite element simulation technology, and particularly relates to a wind turbine hub rapid stress analysis method. The method of the present application firstly constructs a full assembly finite element model containing a hub, a blade prosthesis, a variable pitch bearing, a rotating shaft and connecting bolts, and performs loading and solving; then extracts the node force at the connection between the hub and the three-blade root flange and the three-connection flange, forms a distributed force data set and saves it as a standardized load file; when the hub structure is optimized, a simplified finite element model is constructed based on the optimized hub body, and the distributed force load is accurately loaded to the corresponding flange surface for solving. The present application replaces the mechanical action of the surrounding components with distributed force equivalent, simplifies the complex nonlinear assembly model into a linear hub model, significantly improves the analysis efficiency under the premise of ensuring the calculation accuracy, and is suitable for rapid design and iterative optimization of the hub structure.

Description

Technical Field

[0001] This invention belongs to the field of wind power equipment structural design and finite element simulation technology, specifically involving a method for rapid stress analysis of wind turbine hubs. Background Technology

[0002] The hub is a critical load-bearing component in a wind turbine generator, connecting the blades to the main shaft system. Its function is to bear and transmit complex loads from the blades, including aerodynamic thrust, torque, bending moment, gyroscopic moment, and dynamic loads generated during yaw, start-stop, and pitch control. These loads are transmitted through the blade roots to the pitch bearings, then act on the hub, and finally are transmitted to the main shaft system, converting mechanical energy into electrical energy. Therefore, the structural strength and fatigue life of the hub directly affect the reliability and operational safety of the entire wind turbine generator.

[0003] Currently, the mechanical analysis of wheel hubs mainly employs simulations using an overall assembly model based on the finite element method. For example... Figure 1 As shown, a typical finite element model of a wheel hub includes the hub body, blade spurs, pitch bearings, shaft, and numerous connecting bolts. In this model, external loads are typically applied by setting a loading point at the center of the blade spur, and the shaft is constrained to simulate actual support conditions, thereby evaluating the stress and deformation state of the hub under various operating conditions.

[0004] However, while this traditional holistic modeling method is widely used in engineering practice and, due to its model integrity, ensures the reliability of analysis results to a certain extent, it is always accompanied by a series of long-standing technical limitations. First, because the model involves multiple connecting components (such as three pitch bearings, blade spurs, shafts, and various connecting bolts), the modeling process is complex, cumbersome, and time-consuming. Second, the model contains numerous unavoidable nonlinear factors, including the stiffness nonlinearity of the pitch bearings, the nonlinear preload effect of bolt connections, and the nonlinear behavior of frictional contact between components. These factors collectively lead to a large computational model size, difficulty in nonlinear iterative convergence, extreme sensitivity to parameter settings in the solution process, heavy reliance on the engineering experience of the analysts, low overall computational efficiency, and difficulty in adapting to the rapid design and multi-round iterative development pace.

[0005] Furthermore, during the design and optimization of wheel hub structures, it is often necessary to repeatedly adjust and verify local areas (such as internal chamfers and bosses). If the entire process simulation is continuously performed using the overall assembly model, it will inevitably face problems such as frequent model reconstruction, high computational resource consumption, and lengthy analysis cycles, severely restricting product development efficiency and design flexibility. Although the industry is aware of these issues, under the current technological framework, there is still a lack of a reliable alternative that can maintain the accuracy of the entire model while significantly improving analysis efficiency. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for rapid stress analysis of wind turbine hubs.

[0007] The purpose of this invention is to provide a rapid stress analysis method for wind turbine hubs that can both ensure calculation accuracy and significantly improve analysis efficiency, thereby overcoming the problems of complex modeling, low calculation efficiency, and difficulty in nonlinear convergence in the prior art, and providing effective technical support for the optimized design of wind turbine hubs.

[0008] This invention provides a method for rapid stress analysis of the hub of a wind turbine generator set, comprising the following steps: Step 1: Construct the fully assembled finite element model Based on the finite element calculation standard for wind turbine hubs, the initial hub model and input parameters, a fully assembled finite element model including the hub, three blade spurs, three pitch bearings, the shaft and connecting bolts was built. Step 2: Applying and solving loads on the fully assembled model Constraints and loads are applied to the fully assembled finite element model. Constraints are applied to the connection surface between the rotating shaft and the fixed shaft to restrict the degree of freedom of the rotating shaft. Loads are applied to the center loading points of the three blade root flanges. Working loads are applied in the blade root coordinate system, and finite element solutions are performed to obtain a result file containing the stress and deformation results of all components. Step 3: Extraction and preservation of force distribution on flange face Based on the results file, the nodal forces at the connection between the hub and the three-lobe root flange and the three-connection flange are extracted by finite element software post-processing to form a flange surface force distribution dataset, which is then classified and saved as a standardized load file according to the flange surface type. Step 4: Construct a simplified finite element model of the wheel hub After the hub structure is optimized, a simplified finite element model is constructed based on the optimized hub model. The simplified model only contains the hub body, and the elements corresponding to the three-lobed root flange and the three-connection flange are marked. Step 5: Simplify the load application and result solution of the model The standardized load file is loaded onto the flange surface of the simplified model according to the markings, and finite element analysis is performed to obtain the stress distribution and deformation results of the hub body.

[0009] As a further optimization of the rapid stress analysis method for wind turbine hubs, in step 1, the fully assembled finite element model connects the components with bolts to form a mechanical transmission system consistent with the actual working conditions.

[0010] As a further optimization of the rapid stress analysis method for wind turbine hubs, in step 2, the result file is in rst format and contains stress distribution data and deformation data of the hub, blade spur, pitch bearing, shaft, and bolts.

[0011] As a further optimization of the rapid stress analysis method for wind turbine hubs, in step 3, the mesh structure at the connection between the hub and the flange surface remains unchanged when extracting nodal forces, so as to ensure the accuracy of nodal force extraction.

[0012] As a further optimization of the rapid stress analysis method for wind turbine hubs, step 4 involves optimizing the hub structure by making local improvements to the internal chamfer and boss structures, while keeping the core load-bearing structure unchanged.

[0013] As a further optimization of the rapid stress analysis method for wind turbine hubs, in step 4, when constructing the simplified finite element model, the hub body is meshed and assigned the same material element properties as the original model.

[0014] As a further optimization of the rapid stress analysis method for wind turbine hubs, in step 5, the load is accurately mapped onto the flange surface by element marking when applying the distributed force.

[0015] As a further optimization of the rapid stress analysis method for wind turbine hubs, this method is used for rapid iteration in the hub structure optimization design stage. When the local structure of the hub needs to be improved, the optimization effect can be quickly evaluated by reusing the standardized load file and solving the updated hub body model.

[0016] Beneficial effects Compared with existing technologies, the rapid stress analysis method for wind turbine hubs provided by this invention simplifies the complex fully assembled nonlinear model into a linear model containing only the hub body by "extracting the distributed forces on the flange surfaces connected to the hub" to equivalently replace the effects of surrounding components. This is combined with key steps such as "keeping the flange mesh unchanged to accurately extract nodal forces" and "marking flange elements to achieve precise load mapping." This fundamentally avoids the computational challenges caused by nonlinearities in pitch bearings, bolt connections, and frictional contact. Thus, while ensuring that the stress and deformation analysis accuracy of key hub areas (such as internal chamfers and bosses) is highly consistent with the fully assembled model, it significantly reduces modeling complexity, decreases the number of computational iterations, and significantly shortens the solution time, providing an efficient and reliable analysis method for the rapid design and iterative optimization of hub structures. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the finite element model of the wheel hub.

[0018] Figure 2 This is a schematic cross-sectional view of the finite element model of the wheel hub.

[0019] Figure 3 This is a structural diagram of the hub three-lobe root flange and the shaft connection flange.

[0020] Figure 4 The diagram shows a comparison between the simplified calculation method of this invention and the calculation results of the fully assembled model. In this diagram, (a) is the stress distribution diagram calculated by this invention, and (b) is the stress distribution diagram calculated using the fully assembled finite element model.

[0021] In the diagram, 1 is the hub; 2 is the blade prosthesis; 3 is the shaft; 4 is the pitch bearing; 5 is the bolt; 6 is the triple connecting flange; and 7 is the three-lobe root flange. Detailed Implementation

[0022] The present invention is further illustrated below with specific embodiments. These embodiments are exemplary and intended to illustrate the problem and explain the present invention, and are not intended to be limiting.

[0023] This invention discloses a rapid stress analysis method for wind turbine hubs. By extracting the distributed forces on the flange surfaces connected to the hub, the analysis model is simplified, reducing the computational scale and improving analysis efficiency while ensuring computational accuracy. The hub structure is as follows: Figures 1 to 3 As shown, the specific implementation steps are as follows.

[0024] Step 1: Construct the fully assembled finite element model Based on the existing finite element calculation standard for wind turbine hub 1, the initial model of hub 1 and the preset input parameters, a fully assembled finite element model containing complete related components is built. The model specifically includes hub 1, three blade dummy bodies 2, three pitch bearings 4, shaft 3 and bolts 5 for connecting the components. The components are assembled and fixed by bolts 5 to form a mechanical transmission system consistent with the actual working conditions.

[0025] Step 2: Applying and solving loads on the fully assembled model Constraints and loads are applied to the fully assembled finite element model constructed in step 1. Constraints are applied at the connection surface between the rotating shaft 3 and the fixed shaft to limit the degree of freedom of the rotating shaft 3, so that the model conforms to the actual installation conditions. Then, with the center of the three-leaf root flange 7 as the loading point, loads corresponding to the working conditions are applied to the three loading points in the blade root coordinate system. Subsequently, the finite element solution operation is started to obtain the calculation result file covering all working conditions. The file format is rst and contains stress distribution data and deformation data of hub 1, blade spur 2, pitch bearing 4, rotating shaft 3, and bolt 5.

[0026] Step 3: Extraction and preservation of force distribution on flange face Based on the RST file obtained in step 2, the target distributed force is extracted using the post-processing module of ANSYS software. During the process, the mesh structure at the connection between hub 1 and the three-lobed root flange 7 and the three-connected flange 6 remains unchanged to ensure the accuracy of nodal force extraction. Then, the nodal forces of each node of the three-lobed root flange 7 and the three-connected flange 6 are extracted one by one to form a complete flange surface distributed force dataset. The distributed force data is then classified and organized according to the categories of the three-lobed root flange 7 and the three-connected flange 6, and finally saved as a standardized load file for subsequent simplified model loading.

[0027] Step 4: Construct a simplified finite element model of the wheel hub When the strength of the weak area of ​​hub 1 (specifically the internal chamfer and boss structure) does not meet the design requirements, the optimized hub 1 model provided by the product team is obtained. This model only modifies the chamfer and boss structure, while the core load-bearing structure remains unchanged. When constructing a simplified finite element model based on this optimized model, only the hub 1 body is retained, and the blade spur 2, pitch bearing 4, shaft 3, and bolt 5 are removed. Then, the hub 1 body is meshed with finite element mesh and assigned the same material element properties as the original model. Finally, the elements corresponding to the three-leaf root flange 7 and the three-connection flange 6 on hub 1 are marked for accurate positioning of subsequent load loading.

[0028] Step 5: Simplify the load application and result solution of the model The standardized load file obtained in step 3 is loaded onto the three-leaf root flange 7 and the three-connecting flange 6 of the simplified model constructed in step 4 according to the marking correspondence. Then, the finite element solution operation is started. After the solution is completed, the stress distribution and deformation results of the optimized hub 1 body are obtained.

[0029] The result calculated using the above method is as follows: Figure 4 As shown in (a), the calculation results of the fully assembled model according to step 2 are as follows: Figure 4 As shown in (b), the comparison reveals a high degree of consistency in stress distribution and deformation trends between the two methods. This is particularly evident in the critical load-bearing areas of hub 1, such as the internal chamfers and bosses, where the stress concentration phenomena and numerical ranges are highly similar. This result verifies the reliability and accuracy of the simplified calculation method provided by this invention.

[0030] This invention extracts the distributed forces from the three-lobe root flange 7 and the three-connecting flange 6 in the fully assembled model to equivalently replace the effects of surrounding components (such as blade spurs 2, pitch bearings 4, bolts 5, etc.) on the hub 1. Since the mechanical interaction between the hub 1 and the surrounding components is entirely transmitted through the flange surface, the distributed forces can fully characterize the influence of external loads on the hub 1. During the extraction process, by keeping the flange surface mesh unchanged and extracting nodal forces, the accuracy of the distributed force data is ensured, thereby achieving mechanical boundary conditions consistent with the fully assembled model in the simplified model.

[0031] The fully assembled model involves complex factors such as the nonlinearity of the pitch bearing 4, the nonlinear connection of the bolts 5, and the nonlinear contact of friction, resulting in a large computational scale and poor iterative convergence. However, this invention transforms the problem into a linear calculation by applying distributed force, avoiding these nonlinear elements, significantly reducing computation time and modeling complexity. At the same time, since the extracted distributed force already implies the stiffness and nonlinear effects of the surrounding components, the calculation results can still reflect the real working conditions.

[0032] This invention is particularly suitable for rapid iteration in the structural optimization design phase of hub 1. When local details of hub 1 (such as chamfers and bosses) need improvement, it is not necessary to repeatedly build a fully assembled model including blade spurs 2, pitch bearings 4, shafts 3, and bolts 5. Instead, only the hub 1 body model needs to be updated and pre-extracted distributed force loads reused to quickly evaluate the optimization effect. This not only improves analysis efficiency but also reduces reliance on engineering analysis experience, allowing designers to focus more on structural improvements rather than complex calculation settings.

[0033] Through the above implementation steps and analysis, the present invention successfully simplifies the original fully assembled complex model into a simplified model containing only the hub 1 body. While ensuring the accuracy of the analysis, it significantly shortens the modeling cycle and calculation time, and is suitable for rapid stress analysis and structural optimization design of wind turbine hub 1.

[0034] The above embodiments are exemplary and are intended to illustrate the technical concept and features of the present invention, so that those skilled in the art can understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for rapid stress analysis of the hub of a wind turbine generator set, characterized in that, Includes the following steps: Step 1: Construct the fully assembled finite element model Based on the finite element calculation standard for wind turbine hubs, the initial hub model and input parameters, a fully assembled finite element model including the hub, three blade spurs, three pitch bearings, the shaft and connecting bolts was built. Step 2: Applying and solving loads on the fully assembled model Constraints and loads are applied to the fully assembled finite element model. Constraints are applied to the connection surface between the rotating shaft and the fixed shaft to restrict the degree of freedom of the rotating shaft. Loads are applied to the center loading points of the three blade root flanges. Working loads are applied in the blade root coordinate system, and finite element solutions are performed to obtain a result file containing the stress and deformation results of all components. Step 3: Extraction and preservation of force distribution on flange face Based on the results file, the nodal forces at the connection between the hub and the three-lobe root flange and the three-connection flange are extracted by finite element software post-processing to form a flange surface force distribution dataset, which is then classified and saved as a standardized load file according to the flange surface type. Step 4: Construct a simplified finite element model of the wheel hub After the hub structure is optimized, a simplified finite element model is constructed based on the optimized hub model. The simplified finite element model only contains the hub body, and the elements corresponding to the three-leaf root flange and the three-connection flange are marked. Step 5: Simplify the load application and result solution of the model The standardized load file is loaded onto the flange surface of the simplified model according to the markings, and finite element analysis is performed to obtain the stress distribution and deformation results of the hub body. In step 3, the mesh structure at the connection between the hub and the flange surface remains unchanged when extracting nodal forces to ensure the accuracy of nodal force extraction; In step 4, the optimization of the wheel hub structure is a localized improvement to the internal chamfer and boss structure, while the core load-bearing structure remains unchanged.

2. The method for rapid stress analysis of wind turbine hubs according to claim 1, characterized in that, In step 1, the fully assembled finite element model connects the components with bolts to form a mechanical transmission system consistent with the actual working conditions.

3. The method for rapid stress analysis of wind turbine hubs according to claim 1, characterized in that, In step 2, the result file is in rst format and contains stress distribution data and deformation data of the hub, blade spur, pitch bearing, shaft and bolts.

4. The method for rapid stress analysis of wind turbine hubs according to claim 1, characterized in that, In step 4, when constructing the simplified finite element model, the hub body is meshed and assigned the same material element properties as the original model.

5. The method for rapid stress analysis of wind turbine hubs according to claim 1, characterized in that, In step 5, when applying the distributed force, the load is accurately mapped onto the flange surface through element marking.

6. The method for rapid stress analysis of the hub of a wind turbine generator set according to any one of claims 1-5, characterized in that, The method is used for rapid iteration in the wheel hub structure optimization design stage; when the local structure of the wheel hub needs to be improved, the optimization effect can be quickly evaluated by reusing the standardized load file and solving the updated wheel hub body model.

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