Crack propagation analysis method and device for fan blade considering real environment of sea

Abstract

The present application relates to the field of ocean engineering and mechanical engineering technology, in particular to a fan blade crack propagation analysis method and device considering real marine environment. The method considers real marine environment working conditions, performs dynamic simulation analysis on the fan blade, determines the load distribution information borne by the fan blade and loads it on the finite element model of the fan blade, determines the fatigue hot spot area according to the finite element fatigue damage analysis result and performs crack arrangement. Through the finite element simulation result, the stress intensity factor of the crack tip is calculated and crack propagation simulation is performed to evaluate the fracture failure risk of the fan blade under real marine environment. The fan blade crack propagation analysis idea under complex stress conditions is proposed, which can prevent equipment failure and risk caused by blade fracture, provide a scientific basis for fan maintenance and operation, and thus reduce economic losses caused by fan blade failure.

Description

Technical Field

[0001] This invention relates to the fields of marine engineering and mechanical engineering, specifically to a method and apparatus for analyzing crack propagation in wind turbine blades that takes into account the real marine environment. Background Technology

[0002] Floating offshore wind turbine blades operating in the marine environment are subjected to a combination of complex mechanical and environmental factors. These factors include wind load, gravity load, wave impact, temperature changes, and salt spray corrosion. These forces and environmental conditions can cause the blade materials to gradually fatigue and age, potentially leading to fracture. To ensure the safety and reliability of the blades, their fracture behavior must be thoroughly analyzed and studied.

[0003] Excellent mechanical properties and reliable quality of blades are crucial for ensuring the continuous and stable operation of wind turbine generators. Given the harsh operating environment of wind turbines, blades must possess high fracture resistance and excellent mechanical properties to withstand continuously changing random loads and sudden extreme conditions (such as the impact of extreme weather phenomena like tornadoes). Crack propagation behavior, specifically the crack propagation rate, is typically defined as a function of the crack tip fracture parameters, with the stress intensity factor K being a function of the crack tip fracture parameters. Therefore, analyzing the crack tip fracture parameters of blades is of great significance and can provide important reference value for the design, manufacturing, optimization, and reliability assessment of wind turbine blades. Summary of the Invention

[0004] In view of this, the present invention provides a method and apparatus for analyzing crack propagation of wind turbine blades that takes into account the real marine environment, so as to solve the problem that the existing technology cannot accurately assess the crack propagation situation, resulting in deviations in the prediction results of blade fracture and failure risks.

[0005] In a first aspect, the present invention provides a method for analyzing crack propagation in wind turbine blades considering the real marine environment. The method includes: performing dynamic simulation of the wind turbine blades based on real marine environmental parameters under different marine environmental conditions to determine the load distribution information borne by the wind turbine blades; loading the load distribution information onto the finite element model of the blades to simulate the fatigue damage process of the blades and obtain simulation results; determining the fatigue hotspot areas of the blades throughout their entire life cycle based on the fatigue damage distribution map in the simulation results, and arranging cracks in the finite element model based on the fatigue hotspot areas; resetting a typical operating condition as a new operating condition for wind turbine simulation and load calculation, loading the load distribution information of the new operating condition onto the finite element model with cracks arranged, resimulating the fatigue damage stress loading process of the blades, and obtaining new simulation results; calculating the fracture parameters at the crack tip of the wind turbine blades based on the new simulation results, and then analyzing crack propagation.

[0006] In this invention, the method considers real marine environmental conditions, performs dynamic simulation analysis on wind turbine blades, determines the load distribution information borne by the blades and applies it to the finite element model of the blades. Based on the finite element fatigue damage analysis results, fatigue hotspot regions are identified and crack arrangements are made. Using the finite element simulation results, the stress intensity factor at the crack tip is calculated and crack propagation simulation is performed to assess the risk of wind turbine blade fracture in a real marine environment. This invention proposes a crack propagation analysis approach for wind turbine blades under complex stress conditions, which can prevent equipment failures and risks caused by blade fracture, provide a scientific basis for wind turbine overhaul and maintenance, and thus reduce economic losses caused by wind turbine blade failure.

[0007] In one optional implementation, dynamic simulation of the wind turbine blades is performed based on real marine environmental parameters under different marine environmental conditions to determine the load distribution information borne by the wind turbine blades. This includes: determining the wind speed range of the wind turbine based on the wind speed-power curve of the wind turbine, and dividing the wind speed range into a preset number of wind speed intervals; calibrating turbulence intensity parameters and wave parameters based on real marine environmental conditions under different marine environmental conditions, and determining the wind field parameters for each wind speed interval based on the wave parameters and the wind speed parameters determined by the turbulence intensity parameters; generating a wind field file based on the wind field parameters for each wind speed interval and the wind turbine model parameters; and performing dynamic simulation and load calculation based on the wind field file and environmental parameters to obtain the load information of the wind turbine blades.

[0008] In this invention, the wind speed range of the wind turbine is determined and divided into multiple wind speed intervals. Each wind speed interval can then be defined as a calculation condition for wind turbine simulation. Simultaneously, a wind field file is generated based on the wind field parameters and wind turbine model parameters for each wind speed interval, providing a data foundation for load calculation. Furthermore, when performing load calculations, environmental parameters are considered in addition to the wind field file, making the load determination more consistent with actual conditions.

[0009] In one optional implementation, dynamic simulation and load calculation are performed based on wind field files and environmental parameters to obtain the load information of the wind turbine blades, including: simulating the overall operating response of the wind turbine based on wind field files and environmental parameters to obtain simulation results; determining the load distribution and time history of the wind turbine blades based on blade element momentum theory, beam model and simulation results; and converting the load distribution and time history into equivalent cyclic loads to obtain the load information of the wind turbine blades.

[0010] In one optional implementation, fatigue hotspot regions throughout the blade's life cycle are determined based on the fatigue damage distribution map in the simulation results, and crack layout of the finite element model is performed based on the fatigue hotspot regions. This includes: using finite element software to obtain fatigue damage distribution maps in the simulation results under different marine environmental conditions, determining fatigue hotspot regions throughout the blade's life cycle; and performing crack layout of the finite element model in the fatigue hotspot regions.

[0011] In one alternative implementation, the finite element model comprises multiple elements, and the cracks are arranged in the following manner: at the intersection of elements, new nodes with the same geometric position as the original nodes are generated; the elements adjacent to the new nodes are redefined with the new nodes to generate cracks.

[0012] In this invention, by generating cracks in this manner, the lower node of the upper element and the upper node of the lower element are spatially coincident in adjacent elements, but geometrically and mesh-wise discontinuous. This ensures the realism of the crack setup.

[0013] In one optional implementation, the analysis of crack propagation of the wind turbine blade based on the new simulation results includes: analyzing the blade fracture parameters based on the new simulation results to obtain a first analysis result, wherein the blade fracture parameters include a stress intensity factor; analyzing the blade crack propagation behavior based on the first analysis result to obtain a second analysis result; and performing simulation analysis on the blade crack propagation based on the first and second analysis results.

[0014] In one optional implementation, the stress intensity factor is determined based on the strain energy release rate and elastic modulus under different wind speed ranges; the second analysis result includes the crack propagation rate and stress intensity range; the blade crack propagation is simulated based on the first and second analysis results, including: arranging spring elements with variable stiffness between adjacent elements at the crack tip according to a preset crack propagation path; and performing multiple cyclic simulations by adjusting the stiffness of the spring elements based on the stress intensity factor, crack propagation rate, and stress intensity range to obtain the crack propagation analysis results on the finite element model.

[0015] Secondly, this invention provides a crack propagation analysis device for wind turbine blades considering the real marine environment. The device includes: a load distribution determination module, used to perform dynamic simulation of the wind turbine blade based on real marine environmental parameters under different marine environmental conditions, and determine the load distribution information borne by the wind turbine blade; a loading simulation module, used to load the load distribution information onto the finite element model of the blade, simulate the fatigue damage process of the blade, and obtain simulation results; a crack arrangement module, used to determine the fatigue hotspot area of ​​the blade throughout its entire life cycle based on the fatigue damage distribution diagram in the simulation results, and arrange cracks in the finite element model based on the fatigue hotspot area; a new operating condition simulation module, used to reset the typical operating condition as a new operating condition for wind turbine simulation and load calculation, load the load distribution information of the new operating condition onto the finite element model with arranged cracks, re-simulate the fatigue damage process of the blade, and obtain new simulation results; and an extension analysis module, used to analyze the crack propagation of the wind turbine blade based on the new simulation results.

[0016] Thirdly, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the crack propagation analysis method for wind turbine blades considering the real marine environment described in the first aspect or any corresponding embodiment.

[0017] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the crack propagation analysis method for wind turbine blades considering a real marine environment as described in the first aspect or any corresponding embodiment above.

[0018] Fifthly, the present invention provides a computer program product, including computer instructions for causing a computer to execute the crack propagation analysis method for wind turbine blades considering a real marine environment as described in the first aspect or any corresponding embodiment. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a flowchart illustrating a method for analyzing crack propagation in wind turbine blades considering a real marine environment, according to an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram showing the coupling of all nodes in the cross section with a reference point of the aerodynamic center of the cross section according to an embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of load application in a finite element model according to an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the crack configuration according to an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of crack propagation with cyclic propagation according to an embodiment of the present invention;

[0025] Figures 6(a), 6(b), and 6(c) are schematic diagrams of cracks of different lengths according to embodiments of the present invention;

[0026] Figure 7 This is a flowchart illustrating another method for analyzing crack propagation in wind turbine blades that considers a real marine environment, according to an embodiment of the present invention.

[0027] Figure 8 This is a structural block diagram of a crack propagation analysis device for wind turbine blades that takes into account the real marine environment according to an embodiment of the present invention.

[0028] Figure 9 This is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] According to an embodiment of the present invention, a method for analyzing crack propagation of wind turbine blades considering a real marine environment is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0031] This embodiment provides a crack propagation analysis method for wind turbine blades that considers the real marine environment, which can be used in electronic devices such as computers, mobile phones, and tablets. Figure 1 This is a flowchart of a crack propagation analysis method for wind turbine blades considering a real marine environment, according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0032] Step S101 involves performing dynamic simulations on the wind turbine blades based on real marine environmental parameters under different marine environmental conditions to determine the load distribution information borne by the wind turbine blades. Specifically, the dynamic simulation of the wind turbine blades can be achieved using a wind turbine simulation program. This program, based on the momentum cloud method and the law of conservation of momentum, is used to calculate the translational and rotational motion of a floating wind turbine under combined wind and wave loads. During the simulation, relevant parameters of the wind turbine can be obtained first based on real marine environmental conditions under different marine environmental conditions. Then, the simulation scenario of the wind turbine can be configured. Subsequently, relevant functional modules within the wind turbine can be used for dynamic simulation analysis to determine the load distribution information borne by the wind turbine blades.

[0033] Step S102: Load the load distribution information into the finite element model of the blade, simulate the fatigue damage process of the blade, and obtain the simulation results. Before loading the load distribution information, finite element modeling of the blade can be performed first. For example, a 3D model of the blade can be constructed first, and then imported into finite element modeling software for finite element modeling. In this embodiment, shell elements are used to model the wind turbine blade to improve computational efficiency while maintaining high accuracy. Furthermore, the mesh size is selected to be 0.1m during modeling. In addition, the blade skin material parameters need to be set before modeling. In this embodiment, the blade skin material parameters are selected from commonly used industrial fiberglass (e.g., FRP material with an elastic modulus of 20GPa, Poisson's ratio of 0.15, and density of 2000kg / m³), and the web is usually made of carbon fiber (e.g., T700 carbon fiber material with an elastic modulus of 250GPa, Poisson's ratio of 0.3, and density of 1800kg / m³).

[0034] After constructing the finite element model of the blade, the root nodes of the blade finite element model are fully constrained based on the rigid connection between the blade root and the hub. Starting from the blade root, the blade is divided into m airfoil sections every 2 meters (m is determined by the blade length). All nodes in each section are coupled to a reference point at the aerodynamic center of the section, such as... Figure 2 As shown (including reference points RP-5, RP-6, and RP-7), this coupling allows for relative deformation between the cross-sectional nodes.

[0035] Therefore, when loading load information, such as Figure 3 As shown, load distribution information can be loaded onto m airfoil sections in finite element analysis software (such as ABAQUS, ANASYS, etc.) and finite element analysis calculations can be performed to simulate the stress loading process of the blade in the real working environment.

[0036] Step S103: Based on the fatigue damage distribution map in the simulation results, determine the fatigue hotspot regions throughout the blade's entire life cycle, and arrange the cracks in the finite element model based on these fatigue hotspot regions. Specifically, since the fatigue damage process of the blade is simulated in the finite element software, the stress concentration regions of the blade can be determined through the simulation results of the finite element analysis, and the fatigue damage distribution and fatigue damage region map can be further determined. Assuming that the earliest cracks caused by structural fatigue appear in the fatigue damage region, the crack arrangement in the finite element model can be based on the fatigue damage region. When arranging cracks, crack settings can also be made in the constructed finite element model according to the element structure in the model. Furthermore, since the simulation results are obtained from different marine environmental conditions, by setting conditions covering the entire life cycle of the blade, the fatigue hotspot regions throughout the blade's entire life cycle can be determined through the simulation results.

[0037] Step S104: The typical operating condition is reset as a new operating condition for wind turbine simulation and load calculation. The load distribution information of the new operating condition is loaded onto the finite element model with cracks, and the fatigue damage stress loading process of the blade is re-simulated to obtain new simulation results. Specifically, after cracks are placed in the finite element model of the blade, the typical operating condition can be reset as a new operating condition for wind turbine simulation and load calculation. This calculation process is the same as that in step S101 above. The load distribution information of the new operating condition is loaded onto the finite element model with cracks, and the fatigue damage process of the blade is re-simulated to obtain new simulation results. It should be noted that this typical operating condition and the marine environment condition in step S101 can be the same or different.

[0038] Step S105: Analyze the crack propagation of the wind turbine blade based on the new simulation results. Specifically, since the simulation results are obtained by simulating the fatigue damage process of the blade, the fatigue damage of the blade can be analyzed using the new simulation results. The crack tip stress intensity factor is a key parameter in fracture mechanics, used to describe the stress concentration at the crack tip and determine whether the crack will propagate. Therefore, this embodiment mainly analyzes the crack tip fracture and crack propagation when analyzing the crack propagation of the wind turbine blade.

[0039] This invention provides a method for crack propagation analysis of wind turbine blades considering real marine environments. Taking into account actual marine conditions, the method performs dynamic simulation analysis on the wind turbine blades to determine the load distribution information and applies it to the finite element model of the blades. Based on the finite element fatigue damage analysis results, fatigue hotspot regions are identified and cracks are arranged. Using the finite element simulation results, the stress intensity factor at the crack tip is calculated, and crack propagation simulation is performed to assess the risk of wind turbine blade fracture in a real marine environment. This invention proposes a crack propagation analysis approach for wind turbine blades under complex stress conditions, which can prevent equipment failures and risks caused by blade fracture, providing a scientific basis for wind turbine overhaul and maintenance, thereby reducing economic losses caused by wind turbine blade failure.

[0040] This embodiment provides a method for crack propagation analysis of wind turbine blades considering the real marine environment. The process includes the following steps:

[0041] Step S201: Perform dynamic simulation of the wind turbine blades based on real marine environmental parameters under different marine environmental conditions to determine the load distribution information borne by the wind turbine blades.

[0042] Specifically, step S201 includes:

[0043] Step S2011: Determine the wind speed range of the wind turbine based on its wind speed-power curve, and divide the wind speed range into a preset number of wind speed intervals. The wind speed-power curve describes the relationship between wind speed and power; this curve can be obtained through theoretical calculations, simulations, field measurements, or product specifications. After determining the wind speed-power curve, the wind speed range for the wind turbine simulation calculation can be reasonably set based on the cut-in speed and cut-out speed at the turbine hub height. For example, the lower limit of the wind speed range can be determined by subtracting 5% to 10% of the cut-in speed from the cut-in speed, and by adding 5% to 10% of the cut-out speed to the cut-out speed.

[0044] Before dividing the wind speed ranges, the number of wind speed ranges to be divided must be determined first. Since each wind speed range needs to be analyzed as a calculation condition for wind turbine simulation after division, the number of wind speed ranges can be determined by considering the computational resources and simulation time required for simulation. After determining the number of wind speed ranges, the wind speed range can be divided by the number of wind speed ranges to determine the upper and lower limits of each wind speed range. Then, the wind speed ranges are divided according to the upper and lower limits of each wind speed range.

[0045] Step S2012: Based on the real marine environment under different marine environmental conditions, turbulence intensity parameters and wave parameters are calibrated, and wind field parameters for each wind speed range are determined based on wave parameters and wind speed parameters determined by turbulence intensity parameters.

[0046] The wind field parameters for each wind speed range include the average wind speed and the standard deviation of the wind speed. Specifically, the average wind speed of a wind speed range can be determined by averaging the upper and lower limits of the range. Therefore, based on the upper and lower limits of each wind speed range, the average wind speeds μ1, μ2, ..., μ1 representing that range can be determined one by one. k (k represents the number of wind speed ranges). The wind speed standard deviation can be determined using turbulence model calculation formulas recommended by IEC (International Electrotechnical Commission) standards (e.g., the NTM turbulence model), representing the standard deviation σ1, σ2, ..., σ of that wind speed range. k For example, if the NTM turbulence model recommended by the IEC standard is selected, the standard deviation of wind speed is calculated according to the following formula:

[0047] σ=I ref (0.75μ+5.6) Formula 1

[0048] Where μ represents the average wind speed and I represents the turbulence intensity parameter. refThe value can be selected by referring to the recommended values ​​given in Models A, B, and C of the IEC standard.

[0049] In offshore areas where IEC standards are not applicable, buoy data can be used as a calculation reference, such as buoy data provided in relevant technical documents. By analyzing buoy data, the average wind speed μ for each wind speed range can be calculated. i With the standard deviation of wind speed σ i The linear relationship between them, for the turbulence intensity parameter I ref The values ​​were recalibrated to conform to real marine environmental conditions.

[0050] Similarly, the wave parameters corresponding to each wind speed range can be obtained by analyzing buoy data, or estimated using the wind-wave coupling method in fully developed sea areas.

[0051] Step S2013: Generate wind field files based on wind field parameters and wind turbine model parameters for each wind speed range;

[0052] Specifically, the wind turbine model parameters can be determined based on the wind turbine type. For example, for a floating wind turbine model, hub height and blade length are selected as wind turbine model parameters. After determining the wind field parameters and wind turbine model parameters, wind field simulation software, such as TurbSim, can be used to generate Gaussian wind field files for the corresponding wind speed range. It is generally assumed that the short-term wind speed distribution follows a stationary stochastic process; therefore, the duration of the wind field file and the wind turbine simulation time should generally not exceed 20 minutes.

[0053] Step S2014 involves performing dynamic simulation and load calculations based on the wind field file and environmental parameters to obtain the load information for the wind turbine blades. Before performing load calculations, it is necessary to determine the environmental parameters of the wind turbine's location. For example, in this embodiment, if the wind turbine is a floating offshore wind turbine, the environmental parameters include wave parameters. These wave parameters include the significant wave height and mean peak period. Specifically, the wave parameters corresponding to the wind speed range, i.e., the significant wave height H, can be determined using the fully developed sea state calculation formula or other methods. s (Significant Wave Height) and Peak Period T p The value of (Peak Period). For example, if the fully developed sea state calculation formula is selected, the hub height average wind speed is first converted to a reference height of 19.5 meters, and then the meaningful wave height and average peak period are calculated according to the relevant formula.

[0054] Specifically, step S2014 above includes:

[0055] Step a1: Simulate the overall operating response of the wind turbine based on the wind field file and environmental parameters to obtain simulation results. Specifically, the wind field file and environmental parameters for each wind speed range can be input into the wind turbine simulation program, such as the FAST program, to solve the overall operating response of the wind turbine and obtain the simulation results of the displacement, velocity and acceleration of each component of the wind turbine in each wind speed range.

[0056] Step a2 determines the load distribution and time history of the wind turbine blades based on blade element momentum theory, beam model, and simulation results. Blade element momentum theory calculates the theoretical lift and drag of the blades at different wind speeds. The calculation involves dividing the blade into multiple blade element segments, each considered a small lifting body. The aerodynamic load on each blade element is calculated by considering factors such as wind speed and angle of attack. The beam model treats the blade as a beam, applying beam theory (such as Euler-Bernoulli beam theory or Timoshenko beam theory) to analyze the structural response. When establishing the beam model, factors such as the blade's mass distribution, stiffness distribution, and boundary conditions must be considered to establish a set of dynamic equations.

[0057] Therefore, when determining the load distribution and time history, the aerodynamic loads calculated by the blade element momentum theory can be applied to the beam model, and coupled aeroelastic dynamics analysis can be performed using simulation software and combined with the simulation results. After the simulation is completed, the load distribution (such as the distribution of bending moment, shear force, and torque along the blade length) and time history of the blade can be extracted from the output results.

[0058] Step a3 involves converting the load distribution and time history into equivalent cyclic loads to obtain the load information for the wind turbine blades. Specifically, this conversion requires first classifying the loads into forward and reverse categories based on the load distribution and time history. Then, a rainflow counting algorithm is used to analyze the time history of each load category to identify all load cycles. Finally, the equivalent load spectrum method is used to convert these cycles into equivalent cyclic loads, thereby obtaining the load information for the wind turbine blades.

[0059] Step S202: Load the load distribution information into the finite element model of the blade, simulate the blade fatigue damage process, and obtain the simulation results. For details, please refer to... Figure 1 Step S103 of the illustrated embodiment will not be described again here.

[0060] Step S203: Based on the fatigue damage distribution map in the simulation results, determine the fatigue hot spot area of ​​the blade throughout its entire life cycle, and arrange the cracks in the finite element model based on the fatigue hot spot area.

[0061] Specifically, step S203 includes:

[0062] Step S2031 involves using finite element analysis (FEM) software to obtain fatigue damage distribution maps from simulation results under different marine environmental conditions, thereby identifying fatigue hotspot areas throughout the blade's life cycle. Specifically, FEM analysis can be used to solve for the stress distribution of the blade in various wind speed ranges. After determining the stress distribution, a Mises stress cloud map can be generated in the post-processing module of the FEM software, which visually displays the stress distribution inside the blade in each wind speed range. Furthermore, FEM analysis can be used to determine the fatigue damage distribution map and the fatigue hotspot areas throughout the blade's life cycle.

[0063] Step S2032 involves arranging cracks in the fatigue hotspot region using a finite element model. Besides arranging cracks in the fatigue hotspot region, cracks can also be arranged in some predetermined areas. These predetermined areas include regions bearing the most concentrated loads (tip, leading edge), transition regions (e.g., the transition region from a cylinder to an airfoil and a droplet), and dissimilar regions containing interfaces (with adhesive layers, such as the trailing edge). In this embodiment, the determined locations for arranging cracks include the blade root, 1 / 3 and 2 / 3 of the span direction from the blade root, the maximum chord length and the upper wing spars cap, and the high-pressure side trailing and leading edges.

[0064] In one alternative implementation, when arranging cracks, a new node with the exact same geometric position as the original node can be generated at the intersection of elements; the elements adjacent to the new node are redefined with the new node to generate cracks.

[0065] Specifically, to simulate structural damage under real-world operating conditions, transverse cracks of length *a* are introduced into the crack region. This allows for further evaluation of the impact of these cracks on the overall strength and lifespan of the blade, thus providing a reliable basis for wind turbine blade design optimization. The specific process for setting up the cracks includes: Figure 4 As shown, at the n nodes where elements intersect, n new nodes with the same geometric positions as the original nodes are generated. The n+1 adjacent upper (or lower) elements are then redefined using these newly generated n nodes, thus generating cracks. Using this method, in the set of adjacent upper and lower elements, the lower node of the upper element and the upper node of the lower element coincide in spatial position, but are discontinuous geometrically and in the mesh.

[0066] Step S204: Reset the typical operating condition as a new operating condition for wind turbine simulation and load calculation. Load distribution information of the new operating condition is loaded onto the finite element model with cracks, and the fatigue damage stress loading process of the blades is re-simulated to obtain new simulation results. For details, please refer to [link to relevant documentation]. Figure 1 Step S104 of the illustrated embodiment will not be described again here.

[0067] Step S205: Analyze the crack propagation of the wind turbine blades based on the new simulation results.

[0068] Specifically, step S205 includes:

[0069] Step S2051: Based on the new simulation results, analyze the blade fracture parameters to obtain the first analysis result. The blade fracture parameters include the stress intensity factor. The stress intensity factor is determined based on the strain energy release rate and elastic modulus under different wind speed ranges.

[0070] Specifically, the crack tip stress intensity factor is a key parameter in fracture mechanics, used to describe the stress concentration at the crack tip and determine whether the crack will propagate. The load calculated in the wind turbine simulation is reapplied to the finite element model of the wind turbine blade with a pre-set crack. The strain energy release rate G of the wind speed model in different wind speed ranges is calculated according to Equation 2. I (Taking a type I crack as an example), and then converting it into the stress intensity factor K. I (Formula 3), and obtain its changing trend and maximum value K over time. max and minimum value K min .

[0071]

[0072] In the formula, G I F represents the strain energy release rate. yI Δv represents the nodal force at the crack tip. 3,4 Δa represents the displacement of the element node at the crack tip, B represents the thickness, and Δa represents the crack propagation amount.

[0073]

[0074] In the formula, E represents the elastic modulus, and K I This represents the stress intensity factor.

[0075] Step S2052: Based on the first analysis result, the crack propagation behavior of the blade is analyzed to obtain the second analysis result. Specifically, according to the above-mentioned stress intensity factor calculation method, its variation trend over time and its maximum value K can be obtained. max and minimum value K min Then, based on the maximum value K... max and minimum value K min The difference ΔK yields the stress intensity range. Crack propagation behavior can be described based on the relationship between crack propagation rate and stress intensity range. Therefore, after obtaining the stress intensity range, the crack propagation rate can be determined based on this relationship, and then the crack propagation behavior can be analyzed.

[0076] The crack propagation rate da / dN can be determined by Paris's theorem, that is, the crack propagation rate da / dN is calculated using the following formula:

[0077]

[0078] In addition, the crack propagation rate can also be calculated based on the Forman formula, which is a generalization of the Paris formula and describes three regions simultaneously. The Forman formula can be expressed as follows:

[0079]

[0080] In the formula: C, n, p, and q are material constants determined experimentally; f depends on the stress ratio R; ΔK th K is the threshold value. IC This is the critical stress intensity factor.

[0081] Step S2053: Based on the first and second analysis results, a simulation analysis of blade crack propagation is performed. This simulation analysis process includes: arranging spring elements with variable stiffness between adjacent elements at the crack tip along a preset crack propagation path; and performing multiple cyclic simulations by adjusting the stiffness of the spring elements based on the stress intensity factor, crack propagation rate, and stress intensity range to obtain the crack propagation analysis results on the finite element model.

[0082] Specifically, considering the crack propagation direction, spring elements with variable stiffness are arranged between adjacent elements at the crack tip according to the predicted crack propagation path, such as... Figure 5 As shown, with the increase of the number of cycles, the stiffness coefficient of the spring element continuously decreases. When the amplitude of the stress intensity factor ΔK at the crack tip is greater than the fracture threshold value K... th When the spring element stiffness drops to 0, the spring breaks, and the crack extends along a predetermined direction by one finite element mesh element. This process repeats, and the crack length continuously increases, as shown in Figures 6(a), 6(b), and 6(c).

[0083] As a specific application embodiment of the present invention, such as Figure 7 As shown, the crack propagation analysis method for wind turbine blades considering the real marine environment can be implemented using the following process:

[0084] 1. Configure the calculation conditions.

[0085] 1.1 Divide the calculation conditions.

[0086] Based on the cut-in speed and cut-out speed at the turbine hub height shown in the wind power curve of the wind turbine generator set, the wind speed range for the wind turbine simulation calculation conditions is reasonably set. Taking into account computational resources and simulation time, the wind speed range at the hub height covered by the wind turbine simulation analysis is divided into k wind speed intervals, each wind speed interval corresponding to a calculation condition for a wind turbine simulation.

[0087] 1.2 Estimate marine environmental parameters.

[0088] Based on the upper and lower limits of each wind speed range, determine the average wind speed μ1, μ2, ..., μ3 representing that wind speed range. k The standard deviations of wind speeds σ1, σ2, ..., σ2, representing this wind speed range, are determined using the turbulence model calculation formulas recommended by IEC standards (e.g., the NTM turbulence model). k For example, if the NTM turbulence model recommended by the IEC standard is selected, the standard deviation of wind speed is calculated according to Formula 1.

[0089] σ=I ref (0.75μ+5.6) (Formula 1)

[0090] Among them, the turbulence intensity parameter I ref The value can be selected by referring to the recommended values ​​given in Models A, B, and C of the IEC standard.

[0091] In offshore areas where IEC standards are not applicable, buoy data can be used as a calculation reference, such as buoy data provided by relevant technologies. By analyzing buoy data, the average wind speed μ for each wind speed range can be calculated. i With the standard deviation of wind speed σ i The previous linear relationship, for the turbulence intensity parameter I ref The values ​​were recalibrated to conform to the actual marine environment control.

[0092] Similarly, the wave parameters corresponding to each wind speed range can be obtained by analyzing buoy data, or estimated using the wind-wave coupling method in fully developed sea areas.

[0093] 1.3, Configure the wind farm file.

[0094] For each wind speed range, the wind field model parameters, i.e., the average wind speed μ, are considered. i and wind speed standard deviation σ i The parameters of the floating wind turbine model, such as hub height and blade length, are used to generate Gaussian wind field files for the corresponding wind speed range using wind field simulation software, such as TurbSim. It is generally assumed that short-term wind speed distribution follows a stationary stochastic process; therefore, the duration of the wind field file and the simulation time for the wind turbine are generally limited to no more than 20 minutes.

[0095] 2. Finite element modeling of blades: Finite element modeling of blades includes blade structure modeling, blade material settings, and blade mesh generation.

[0096] The blade skin material parameters are selected from commonly used industrial fiberglass (e.g., FRP material with an elastic modulus of 20 GPa, Poisson's ratio of 0.15, and density of 2000 kg / m³), while the web is typically made of carbon fiber (e.g., T700 carbon fiber material with an elastic modulus of 250 GPa, Poisson's ratio of 0.3, and density of 1800 kg / m³). Compared to solid elements, shell elements can significantly improve computational efficiency while maintaining high accuracy; therefore, shell elements are chosen to model the wind turbine blade, with each mesh size divided at 0.1 m. Based on the rigid connection between the blade root and the hub, the root nodes of the blade finite element model are fully constrained. Starting from the blade root, the blade is divided into m airfoil sections every 2 meters (m is determined by the blade length). All nodes in each section are coupled to a reference point at the aerodynamic center of the section; this coupling allows for relative deformation between the section nodes.

[0097] 3. Wind turbine dynamics simulation. Wind turbine dynamics simulation includes solving the overall motion response of the wind turbine, deriving the time history of blade interface loads, and calculating blade deformation and stress.

[0098] Substituting the wind field file and wave parameters from step 1.3 into the wind turbine simulation program, the overall motion response of the wind turbine is solved, yielding simulation results for the displacement, velocity, and acceleration of each component. Using the Blade Element Method and Beam Model, combined with the simulation results, the load distribution and time history of the wind turbine blades are calculated. The calculated load time histories for each section are converted into equivalent cyclic loads. These processed loads are then applied to m airfoil sections using finite element analysis software (e.g., ABAQUS, ANASYS), and finite element analysis is performed to simulate the blade's stress loading process in a real working environment.

[0099] 4. Blade Crack Layout. Blade crack layout includes calculating blade fatigue damage, identifying fatigue hotspot regions, and the crack layout in the finite element model.

[0100] It is generally believed that fatigue damage, leading to fracture, is prone to occur at the blade root, approximately 1 / 3 and 2 / 3 of the span from the blade root, the maximum chord length, the upper wing spar cap, and the trailing and leading edges on the high-pressure side. Through finite element analysis of wind turbine blades, and by comprehensively considering the distribution of fatigue losses under different operating conditions, the crack distribution areas were determined.

[0101] To simulate structural damage under real-world conditions, transverse cracks of length *a* are introduced into the crack region. This design is used to further evaluate the impact of these cracks on the overall strength and lifespan of the blades, thus providing a reliable basis for wind turbine blade design optimization. The specific process is as follows: at the *n* nodes where elements intersect, *n* new nodes with the same geometric positions as the original nodes are generated. The adjacent *n+1* upper (or lower) elements are then redefined using these newly generated *n* nodes, generating cracks. Through this method, in the set of adjacent upper and lower elements, the lower nodes of the upper element and the upper nodes of the lower element coincide in spatial position, but are discontinuous geometrically and in the mesh.

[0102] 5. Crack propagation analysis. Crack propagation analysis includes finite element simulation analysis of the crack tip, calculation of fracture parameters at the crack tip, and crack propagation rate.

[0103] The crack tip stress intensity factor is a key parameter in fracture mechanics, used to describe the stress concentration at the crack tip and determine whether the crack will propagate. The loads calculated in the wind turbine simulation under new operating conditions are reapplied to the finite element model of the wind turbine blade with a pre-set crack. The strain energy release rate G is calculated at different wind speed ranges. I (Taking a type I crack as an example), and then converting it into the stress intensity factor K. I (Formula 3), and obtain its changing trend and maximum value K over time. max and minimum value K min .

[0104] Crack propagation behavior can be described by the relationship between the cyclic crack propagation rate da / dN and the stress intensity range ΔK. When the intensity factor ΔK is less than its critical value K... IC When the crack propagation rate da / dN is given, it can be determined by Paris's theorem. The Forman formula is a generalization of Paris's formula, describing all three regions simultaneously, meaning that the Forman formula can be used to analyze crack propagation behavior in other regions.

[0105] Considering the crack propagation direction, spring elements with variable stiffness are arranged between adjacent elements at the crack tip according to the predicted crack propagation path. As the number of cycles increases, the stiffness coefficient of the spring elements continuously decreases. When the stress intensity factor amplitude ΔK at the crack tip exceeds the fracture threshold value K... th When the spring element stiffness drops to 0, the spring breaks, and the crack extends along a predetermined direction through a finite element mesh element. This process repeats, and the crack length continuously increases.

[0106] This embodiment also provides a crack propagation analysis device for wind turbine blades that considers the real marine environment. This device is used to implement the above embodiments and preferred embodiments, and details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0107] This embodiment provides a crack propagation analysis device for wind turbine blades that takes into account the real marine environment, such as... Figure 8 As shown, it includes:

[0108] The load determination module 81 is used to perform dynamic simulation of wind turbine blades based on real marine environmental parameters under different marine environmental conditions, and to determine the load distribution information borne by the wind turbine blades.

[0109] Simulation module 82 is used to load load distribution information into the finite element model of the blade, simulate the fatigue damage process of the blade, and obtain simulation results.

[0110] The crack layout module 83 is used to determine the fatigue hotspot region of the blade throughout its entire life cycle based on the fatigue damage distribution map in the simulation results, and to lay out the cracks in the finite element model based on the fatigue hotspot region.

[0111] The re-simulation module 84 is used to reset the typical operating conditions as new operating conditions for wind turbine simulation and load calculation. The load distribution information of the new operating conditions is loaded into the finite element model with cracks, and the fatigue damage process of the blades is re-simulated to obtain new simulation results.

[0112] Extended analysis module 85 is used to analyze crack propagation in wind turbine blades based on new simulation results.

[0113] In one optional implementation, the load determination module includes: a wind speed division module, used to determine the wind speed range of the wind turbine based on the wind speed-power curve of the wind turbine, and divide the wind speed range into a preset number of wind speed intervals; a wind field parameter determination module, used to calibrate the turbulence intensity parameters and wave parameters based on the real marine environment under different marine environmental conditions, and to determine the wind field parameters of each wind speed interval based on the wave parameters and the wind speed parameters determined by the turbulence intensity parameters; a wind field file generation module, used to generate a wind field file based on the wind field parameters of each wind speed interval and the wind turbine model parameters; and a load determination submodule, used to perform dynamic simulation and load calculation based on the wind field file and environmental parameters to obtain the load distribution information of the wind turbine blades.

[0114] In one optional implementation, the load determination submodule is specifically used for: simulating the overall operating response of the wind turbine based on wind field files and environmental parameters to obtain simulation results; determining the load distribution and time history of the wind turbine blades based on blade element momentum theory, beam model, and simulation results; and converting the load distribution and time history into equivalent cyclic loads to obtain the load information of the wind turbine blades.

[0115] In one optional implementation, the crack arrangement module is specifically used to obtain fatigue damage distribution maps from simulation results under different marine environmental conditions using finite element software, determine fatigue hotspot areas throughout the blade's life cycle, and arrange cracks in the finite element model within the fatigue hotspot areas.

[0116] In one alternative implementation, the finite element model comprises multiple elements, and the cracks are arranged in the following manner: at the intersection of elements, new nodes with the same geometric position as the original nodes are generated; the elements adjacent to the new nodes are redefined with the new nodes to generate cracks.

[0117] In one optional implementation, the extended analysis module includes: a first molecular module for analyzing blade fracture parameters based on new simulation results to obtain a first analysis result, wherein the blade fracture parameters include a stress intensity factor; a second analysis module for analyzing blade crack propagation behavior based on the first analysis result to obtain a second analysis result; and a simulation analysis module for performing simulation analysis on blade crack propagation based on the first and second analysis results.

[0118] In one optional implementation, the stress intensity factor is determined based on the strain energy release rate and elastic modulus under different wind speed ranges; the second analysis result includes the crack propagation rate and stress intensity range; the simulation analysis module is specifically used to arrange spring elements with variable stiffness between adjacent elements at the crack tip according to the preset crack propagation path; based on the stress intensity factor, crack propagation rate and stress intensity range, the stiffness of the spring elements is adjusted to perform multiple cyclic simulations to obtain the crack propagation analysis results on the finite element model.

[0119] Further functional descriptions of the above modules are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0120] This invention also provides a computer device having the above-described features. Figure 8 The device shown is for analyzing the crack propagation of wind turbine blades in a real marine environment.

[0121] Please see Figure 9 , Figure 9 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 9As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 9 Take a processor 10 as an example.

[0122] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GPA), or any combination thereof.

[0123] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0124] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device as shown by a landing page for an app. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, which can be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0125] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0126] The computer device also includes a communication interface 30 for communicating with other devices or communication networks.

[0127] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0128] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0129] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method of crack propagation analysis of a wind turbine blade considering a real environment of the sea, characterized by, The method comprises: Performing dynamic simulation on the wind turbine blade based on real marine environment parameters under different marine environment conditions to determine load distribution information borne by the wind turbine blade; Loading the load distribution information to a finite element model of the blade to simulate a fatigue damage process of the blade and obtain a simulation result; Determining a fatigue hot spot area of the blade in a whole life cycle according to a fatigue damage distribution map in the simulation result, and arranging a crack in the finite element model based on the fatigue hot spot area; Re-setting a typical condition as a new condition to perform wind turbine simulation and load calculation, loading load distribution information of the new condition to the finite element model with the arranged crack, re-simulating the fatigue damage process of the blade, and obtaining a new simulation result; Analyzing crack propagation of the wind turbine blade according to the new simulation result.

2. The method of claim 1, wherein, Performing dynamic simulation on the wind turbine blade based on real marine environment parameters under different marine environment conditions to determine load distribution information borne by the wind turbine blade, comprising: Determining a wind speed range of the wind turbine according to a wind speed-power curve of the wind turbine, and dividing the wind speed range into a preset number of wind speed intervals; Calibrating a turbulence intensity parameter and a wave parameter based on real marine environment under different marine environment conditions, and determining wind field parameters of each wind speed interval based on the wave parameter and a wind speed parameter determined by the turbulence intensity parameter; Generating a wind field file based on the wind field parameters of each wind speed interval and wind turbine model parameters; Performing dynamic simulation and load calculation according to the wind field file and environment parameters to obtain load information of the wind turbine blade.

3. The method of claim 2, wherein, Performing dynamic simulation and load calculation according to the wind field file and environment parameters to obtain load information of the wind turbine blade, comprising: Simulating overall operation response of the wind turbine based on the wind field file and environment parameters to obtain a simulation result; Determining load distribution and time history of the wind turbine blade based on the simulation result, a blade element momentum theory and a beam model; Converting the load distribution and time history into equivalent cyclic load to obtain the load information of the wind turbine blade.

4. The method of claim 2, wherein, Determining a fatigue hot spot area of the blade in a whole life cycle according to a fatigue damage distribution map in the simulation result, and arranging a crack in the finite element model based on the fatigue hot spot area, comprising: Obtaining the fatigue damage distribution map in the simulation result under different marine environment conditions by using a finite element software to determine the fatigue hot spot area of the blade in the whole life cycle; Arranging the crack in the finite element model in the fatigue hot spot area.

5. The method of claim 4, wherein, The finite element model comprises a plurality of elements, and the crack is arranged by using the following process: Generating a new node having a same geometric position as an original node at an intersection of elements; Re-defining elements adjacent to the new node by the new node to generate the crack.

6. The method of claim 1, wherein, Analyzing crack propagation of the wind turbine blade according to the new simulation result, comprising: Analyzing blade fracture parameters according to the new simulation result to obtain a first analysis result, wherein the blade fracture parameters comprise a stress intensity factor; Analyzing crack propagation behavior of the blade based on the first analysis result to obtain a second analysis result; Simulating and analyzing crack propagation of the blade based on the first analysis result and the second analysis result.

7. The method of claim 6, wherein, The stress intensity factor is determined based on strain energy release rate and elastic modulus under different wind speed intervals; and the second analysis result includes crack propagation rate and stress intensity range. Based on the first analysis result and the second analysis result, simulation analysis is performed on the crack propagation of the blade, including: A spring unit with variable stiffness is arranged between the adjacent units at the crack tip according to a preset crack propagation path; Based on the stress intensity factor, the crack propagation rate and the stress intensity range, the stiffness of the spring unit is adjusted for multiple cycles of simulation to obtain the crack propagation analysis result on the finite element model.

8. An apparatus for analyzing crack propagation of a wind turbine blade considering a real environment of the sea, characterized by, The device comprises: A load distribution determination module for determining the load distribution information borne by the fan blade based on dynamic simulation of the fan blade under different marine environmental conditions according to marine real environment parameters; A load simulation module for loading the load distribution information to the finite element model of the blade to simulate the fatigue damage process of the blade and obtain a simulation result; A crack arrangement module for determining the fatigue hot spot area of the blade in the whole life cycle according to the fatigue damage distribution map in the simulation result, and arranging the crack of the finite element model based on the fatigue hot spot area; A new condition simulation module for resetting the typical condition as a new condition to perform fan simulation and load calculation, loading the load distribution information of the new condition to the finite element model with the arranged crack, re-simulating the fatigue damage process of the blade, and obtaining a new simulation result; An expansion analysis module for analyzing the crack propagation of the fan blade according to the new simulation result.

9. A computer device, comprising: It comprises: A memory and a processor, which are communicatively connected, the memory stores computer instructions, and the processor executes the computer instructions to perform the crack propagation analysis method of the fan blade considering the real marine environment according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer instructions for making the computer execute the crack propagation analysis method of the fan blade considering the real marine environment according to any one of claims 1 to 7.

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