A quantitative repair decision-making method for delamination damage of wind turbine blade main beam

Abstract

The present invention belongs to the technical field of wind turbine blades, and in particular relates to a quantitative repair decision-making method for delamination damage of the main beam of a wind turbine blade. It solves the gap in the existing technology and breaks through the technical difficulties in implementing repair decisions for the main beam of a wind turbine blade. It comprises: step 1, for delamination damage of the main beam of a wind turbine blade, establishing a rectangular unit of the blade cross-section ply structure and calculating structural characteristics such as cross-section stiffness; step 2, establishing a quantitative calculation method for the degree of influence of delamination damage of the blade main beam on the deformation of the full-size blade tip; step 3, establishing an experimental research method for quantitative matching of multiple repair parameters and calculating the repair cost; step 4, establishing a repair decision piecewise function expression model and determining four quantitative methods for repair decisions.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind turbine blades, and in particular relates to a quantitative repair decision-making method for delamination damage of a main beam of a wind turbine blade. Background Art

[0002] The wind power R&D team studied the probability of wind power system failures, downtime caused by failures, and structural damage and operation and maintenance technologies. The research revealed that blades are the critical load-bearing structures of wind turbines, receiving the most significant investment in maintenance and overhaul. Therefore, wind turbine blades are considered a key milestone component of wind power generation systems. The main beam, as the primary load-bearing member of the blade structure, maintains excellent structural properties, crucial for ensuring safe blade operation. Currently, the main beams of in-service wind turbine blades are typically vacuum infused, with dozens of layers. Due to process factors such as resin properties and flow path layout, these defects are prone to developing primary defects such as wrinkles and voids. As blades age, these diffusely distributed primary defects within the main beams, under coupled loads, cause localized stress concentrations and gradually evolve into delamination. This delamination damage significantly reduces the local strength and stiffness of the blade and can even lead to catastrophic failure of the entire blade. Therefore, research is imperative on decision-making methods for repairing delamination damage in wind turbine blade main beams.

[0003] Faced with the enormous wind turbine operation and maintenance market and the inevitable delamination caused by inherent defects in blade main beams, damage repair technology has become a crucial support method for ensuring the safe service life of blades throughout their entire service lifecycle. Poor delamination repair cannot effectively restore the blade's sustained load-bearing capacity and may conceal the primary cause of delamination damage, rendering the repair technology a "symptom-treating" approach. This is the primary reason for the low efficiency of delamination repair. Furthermore, ineffective repair not only makes repair costs uncontrollable, but also leads to improper repair parameter design due to the deliberate pursuit of cost reduction. This can cause the repaired area to become the weakest structural area of ​​the in-service blade. This can lead to recurrence of damage after a short period of service, necessitating secondary repairs, resulting in an unlimited increase in repair costs and even greater risk of blade fracture after main beam repair, resulting in even greater economic losses. The lack of a quantitative repair decision-making model based on repair cost to directly guide project implementation has led to the current state of wind turbine blade delamination repair technology in my country, with its empirically based parameters and ambiguous repair costs, a major concern for the blade operation and maintenance industry. Therefore, an expression model for a quantitative repair decision-making method that can accurately calculate the repair cost of blade main beam delamination damage is proposed. This can alleviate the stubborn problems of low blade operation and maintenance efficiency and high maintenance costs to a certain extent, and has great engineering application value in ensuring that repair decisions strike a balance between maximizing safety margins and minimizing economic costs. Summary of the Invention

[0004] The present invention addresses the shortcomings of the existing technology and provides a quantitative repair decision-making method for delamination damage of wind turbine blade main beams. It solves the gap in the existing technology and overcomes the technical difficulties in implementing wind turbine blade main beam repair decision-making.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions: a quantitative repair decision-making method for delamination damage of a wind turbine blade main beam, comprising:

[0006] Step 1: For the delamination damage of the main beam of the wind turbine blade, a rectangular unit of the blade cross-section ply structure is established to calculate the structural characteristics such as the cross-section stiffness;

[0007] Step 2: Establish a quantitative calculation method for the influence of blade main beam delamination damage on the deformation of the full-size blade tip;

[0008] Step 3: Establish a test research method for quantitative matching of multiple restoration parameters and calculate the restoration cost;

[0009] Step 4: Establish a piecewise function expression model for repair decision-making and determine the quantitative methods of four repair decisions.

[0010] Furthermore, the delamination of the wind turbine blade main beam delamination damage is located between or on the surface of the blade main beam laminate. The geometric characteristics of the delamination are defined as the delamination span position, delamination width and delamination depth (number of delamination layers). The plies in the delamination area do not participate in the calculation of structural characteristics.

[0011] Furthermore, the calculation of structural properties such as section stiffness (in step 1) includes:

[0012] Step 1.1: The blade structure cross-section is an airfoil shape. The airfoil geometry is discretized into 200 coordinate points using the equal division method to calculate the ply stiffness characteristics.

[0013] Step 1.2: Use two adjacent geometric coordinate points of the airfoil section as the length of the rectangular unit, use h1 to represent the thickness of the first skin layer and define it as the i-th rectangular unit, i = 1, 2...N, N is defined as the maximum number of units in the section, divide the airfoil section into 200 coordinate points, and sample N = 199 rectangular units. Define the angle θ between the long side of the rectangular unit and the chord length direction of the section;

[0014] At this time, the coordinates of the point ABCD of the i-th rectangular unit are D(Z[i],Y[i]),C(Z[i+1],Y[i+1]),A(Z'[i],Y'[i]),B(Z'[i+1],Y'[i+1]);

[0015] Among them, the coordinates of vertices C and D are directly extracted from the geometric shape of the airfoil section;

[0016] The coordinates of the vertex A of the rectangular unit are calculated as Z'[i]=Z[i]-h1*cosθ, Y'[i]=Y[i]+h1*sinθ,

[0017] The coordinates of vertex B are calculated as Z'[i+1]=Z[i+1]-h1*cosθ, Y'[i+1]=Y[i+1]+h1*sinθ;

[0018] Step 1.3, calculate the second-order moment of inertia of the rectangular element with respect to the flapping coordinate system:

[0019]

[0020]

[0021] Where, ΔZ'=h1*cosθ, ΔY'=h1*sinθ;

[0022] Step 1.4, (weighted sum of each rectangular unit of the blade section) calculate the second-order moment of inertia of the first skin layer as

[0023] The algorithms for the rectangular elements of the other layers are the same as those for the first skin layer. (Therefore, the algorithms for the other inherent properties are the same as those for the skin layer. Also, the algorithms for the rectangular elements of layer N are the same as those for the first skin layer. Therefore, the algorithms for the inherent properties of layer N are the same as those for the skin layer.)

[0024] Step 1.5: Calculate the structural stiffness EI of the blade section ZZ =∑(E j I ZZj ), EI YY =∑(E j I YYj ), where j represents the jth material in the blade structure, j = 1, 2…M, and M is defined as the maximum number of materials selected for the section; E j is the elastic modulus of the j material in the fiber direction, such as epoxy 0° unidirectional fabric E = 40 GPa, ±45 / 0° epoxy triaxial fabric E = 28 GPa, ±45° epoxy biaxial fabric E = 14 GPa; EI ZZ represents the section flapping stiffness, EI YY Represents the section shimmy stiffness.

[0025] Specifically, each blade section consists of multiple plies, each with different material properties and individual thicknesses. The structural stiffness of the blade section is derived by taking a weighted sum of the ply materials. After calculating the stiffness characteristics of each blade structural section using rectangular elements, the blade section is discretized into multiple sections along the span from root to tip using an equidistant method. The stiffness is represented using logarithmic coordinates, and scattered point fitting is used to determine the spanwise distribution of flapping and shimmying stiffness.

[0026] Furthermore, (in step 2) establishing a quantitative calculation method for the influence of blade main beam delamination damage on full-size blade tip deformation includes:

[0027] Step 2.1, calculate the curvature of the sth section based on the section bending moment, flapping stiffness, and shimmy stiffness: s=1,2…L,L is defined as the maximum number of discrete sections along the blade span direction; where M y is the flapping bending moment around the y-axis of the flapping vibration coordinate system, M z is the shimmying bending moment about the z-axis of the flapping shimmying coordinate system;

[0028] Step 2.2, calculate the curvature of the sth section:

[0029]

[0030]

[0031] Where β is the twist angle of the section chord length relative to the blade tip chord length;

[0032] Step 2.3, the cumulative rotation angle of the blade section is calculated as:

[0033]

[0034]

[0035] Where, the first blade root section and x is the discrete cross-sectional length of the blade, x s is the length of the sth blade section, x L is the total span length of the blade;

[0036] In step 2.4, the cumulative deformation of the blade section is calculated as:

[0037]

[0038]

[0039] Where, the first blade root section and

[0040] The blade section is discretized into multiple sections from the blade root to the blade tip along the span direction according to the equidistance method. The tip deformation in the flapping direction and the shimmy direction distributed along the blade span direction are obtained by scatter point fitting.

[0041] Furthermore, in step 3, a test research method for quantitative matching of multiple repair parameters is established, and the calculation of the repair cost includes:

[0042] Step 3.1: Prepare multiple sets of one-way slab repair specimens with a specimen length of 420-600 mm, a specimen width of 50 mm, a lap width of 80 mm and 100 mm, a number of lap surfaces of 1, 2, and 3, a number of reinforcement layers of 0, 1, and 2, a lap method of double lap and single lap, and a reinforcement method of single-sided and double-sided. The specimen specifications are as follows:

[0043]

[0044] Step 3.2: Tensile tests were conducted on all specimens. Strain gauges were placed in the stepped overlap area, the motherboard, and the patch location according to the different specimen specifications. The tensile test performance of the repaired specimens was statistically analyzed to verify the influence of the quantitative combination of multiple repair parameters on the overall failure load of the specimens, which was determined by the experiments.

[0045] Step 3.3, the tensile stress-strain curve of the specimen obtained by the test is used to obtain the influence of the multi-repair parameter quantitative matching scheme on the repair stiffness turning point, and the repair cost C is calculated by the multi-repair parameter quantitative matching scheme. rep :

[0046] C rep =C m +C r +C0

[0047] Where C m is the cost of repair materials, C r is the repair labor cost, C0 is the scheduling cost;

[0048] Repair costs p=1,2…D, D is the total number of types of restoration materials used, M p is the amount of material p, Q p is the unit price of the p-th material;

[0049] Assume that the repair method is A = [1, 2], where A = 1 represents the repair on the tower, and A = 2 represents the repair below the tower; the repair labor cost C r =T*F*H, where T is the maximum number of hours for repair, F is the number of repair workers, and H is the labor cost for repair; when A=1, T=48, F=2, H=200; when A=2, T=120, F=6, H=800;

[0050] Scheduling cost C0=C1+C2, when A=1, C1=2000, C2=2000, when A=2, C1=100000, C2=20000.

[0051] Furthermore, the step 4, establishing a piecewise function expression model for repair decision making, and determining the quantitative methods of the four repair decisions include:

[0052] Step 4.1, define the four repair decisions for blade main beam delamination damage as no repair, repair on the tower, repair below the tower, and scrapping;

[0053] Step 4.2: Define the repair decision model using piecewise function expression. Let piecewise function F = f(k′), where Where C blade is the manufacturing cost of the blade, which is a fixed value according to the blade model;

[0054] Step 4.3, when 0≤k′<0.5%, F=0; when 0.5%≤k′<10%, When 10%≤k′<20%, ​​F=0.5(K-10%)+10%; when k′≥20%, F=2(k-20%)+30%;

[0055] In step 4.4, a piecewise function method is used to establish a quantitative repair decision model.

[0056] Compared with the prior art, the present invention has beneficial effects.

[0057] The present invention can accurately and efficiently calculate the stiffness characteristics of the blade section: based on the blade section rectangular unit sampling method, the stiffness characteristics of the ply are calculated. When the width and depth of the delamination damage are determined, the numerical results of the stiffness characteristic changes caused by delamination can be accurately calculated, thereby accurately and quickly capturing the impact of delamination damage on stiffness.

[0058] The present invention accurately calculates the degree of influence of delamination damage on the deformation of the full-size blade tip: based on the discrete cross-sectional structural characteristics of the blade and the deformation calculation method, the full-size blade is discretized and the cross-sectional rotation angle and deformation are linearly superimposed to achieve accurate calculation of the deformation of the full-size blade tip.

[0059] The present invention realizes quantitative calculation of repair cost by quantitatively matching repair parameters: based on the tensile test of series specimens with quantitative matching of multiple repair parameters, the repair cost including the repair material cost, repair labor cost and scheduling cost is calculated to realize quantitative calculation of repair cost.

[0060] The present invention adopts a piecewise function repair decision expression model to realize the quantitative selection of four repair decisions: based on the numerical value of the influence of blade main beam delamination on the deformation of blade tip flapping direction and the quantitative distribution of repair cost, four repair decisions are determined to realize the quantitative decision-making method of repair stratification. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The present invention is further described below with reference to the accompanying drawings and specific embodiments. The scope of protection of the present invention is not limited to the following description.

[0062] Figure 1 Flowchart of the calculation method.

[0063] Figure 2 Schematic diagram of the blade main beam layering.

[0064] Figure 3 Schematic diagram of the main beam layering characteristics.

[0065] Figure 4 Coordinate system for calculating blade cross-section structural characteristics.

[0066] Figure 5 Schematic diagram of the principle of calculating section stiffness characteristics using the rectangular element sampling method.

[0067] Figure 6 Full-scale blade stiffness distribution diagram.

[0068] Figure 7 Schematic diagram of a full-scale blade discrete cross-section.

[0069] Figure 8 Full-scale blade deformation distribution diagram.

[0070] Figure 9 Schematic diagram of repair parameters for main beam repair using stepped overlapped excavation and patching.

[0071] Figure 10 Strain gauge arrangement position for repair test.

[0072] Figure 11 Multiple repair parameters were quantified to match the tensile stress-strain curves of the specimens.

[0073] Figure 12 A piecewise function expression model for quantitative repair decision-making. DETAILED DESCRIPTION

[0074] Decision-making method of the present invention:

[0075] First, based on the blade section rectangular unit sampling method, the stiffness characteristics of the blade section ply are calculated. When the width and depth of the delamination damage are determined, the numerical results of the stiffness characteristic changes caused by delamination can be accurately calculated, thereby accurately and quickly capturing the impact of delamination damage on stiffness.

[0076] Secondly, based on the discretized blade profile structural characteristics and deformation calculation method, the profile rotation angle and deformation are linearly superimposed to achieve accurate calculation of the full-size blade tip deformation.

[0077] Furthermore, based on the tensile test of a series of specimens with quantitative matching of multiple repair parameters, the repair cost including the repair material cost, repair labor cost and scheduling cost is calculated to achieve quantitative calculation of the repair cost.

[0078] Finally, a repair decision expression model based on piecewise functions is used to realize the quantitative selection of four repair decisions: based on the numerical value of the impact of blade main beam delamination on the deformation of the blade tip in the flapping direction and the quantitative distribution of repair costs, four repair decisions are determined to realize a quantitative decision-making method for repair stratification.

[0079] The examples are as follows:

[0080] like Figure 1 As shown, the overall process of the present invention includes 4 parts.

[0081] like Figure 2 As shown, the main beam is a very important load-bearing structural component of the wind turbine blade, running through the entire span length of the blade. Its delamination damage needs to be clearly located in the span position and cross-sectional position. Delamination often occurs between the layers of the blade main beam thickness, significantly affecting the stiffness characteristics of the blade, and needs to be repaired as soon as possible to restore the blade's safe operation capability.

[0082] like Figure 3 As shown in the figure, the characteristic description of the main beam layering is the layer width and the number of layers, which realizes the geometric characteristic characterization of the layering. The main beam unit representing this area at the layering does not participate in the calculation of the blade structural characteristics.

[0083] like Figure 4 As shown in Figure 1, the flapping coordinate system for calculating the blade profile structural characteristics has a coordinate origin of the profile pitch axis, the y-axis is the profile chord length direction, the z-axis is perpendicular to the profile chord length, and the angle β is the torsion angle of the profile chord length relative to the blade tip chord length.

[0084] like Figure 5 As shown in the figure, based on the geometric coordinate points of the blade airfoil section, two adjacent coordinate points are taken as the length segment of the rectangular unit, h1 is used to represent the thickness of the first skin layer and then defined as the i-th rectangular unit, i = 1, 2...N, N is defined as the maximum number of units in the section, and after the airfoil section is divided into 200 coordinate points, N = 199 rectangular units will be sampled out, and the angle θ between the long side of the rectangular unit and the chord length direction of the section is defined.

[0085] The coordinates of the ABCD points of the i-th rectangular unit are D(Z[i],Y[i]),C(Z[i+1],Y[i+1]),A(Z'[i],Y'[i]),B(Z'[i+1],Y'[i+1]); among them, the coordinates of vertices C and D are directly extracted from the geometric shape of the airfoil section, the coordinates of the vertex A of the rectangular unit are calculated as Z'[i]=Z[i]-h1*cosθ, Y'[i]=Y[i]+h1*sinθ, and the coordinates of the vertex B are calculated as Z'[i+1]=Z[i+1]-h1*cosθ, Y'[i+1]=Y[i+1]+h1*sinθ.

[0086] Next, calculate the second moment of inertia of the rectangular element with respect to the flapping coordinate system:

[0087]

[0088]

[0089] Where, ΔZ'=h1*cosθ, ΔY'=h1*sinθ.

[0090] Calculate the second-order moment of inertia of the first skin layer as follows:

[0091] To calculate the structural properties of other plies in the cross section, the algorithm for the rectangular elements of ply 2 is the same as that for the rectangular elements of the first skin ply, so the algorithm for the inherent properties of ply 2 is the same as that for the skin ply. Furthermore, the algorithm for the rectangular elements of ply N is the same as that for the rectangular elements of the first skin ply, so the algorithm for the inherent properties of ply N is the same as that for the skin ply.

[0092] The cross-sectional structural characteristics are calculated based on the structural characteristics of all plies in the blade section. Each section of the blade contains multiple plies, and each ply has different material properties and single-layer thickness. The weighted sum of the materials of each ply gives the structural stiffness of the blade section:

[0093] EI ZZ =∑(E j I ZZj )

[0094] EI YY =∑(E j I YYj )

[0095] Where j represents the jth material in the blade structure, j = 1, 2…M, MM, M is defined as the maximum number of selected materials in the section; E jis the elastic modulus of the j material in the fiber direction, such as epoxy 0° unidirectional fabric E = 40 GPa, ±45 / 0° epoxy triaxial fabric E = 28 GPa, ±45° epoxy biaxial fabric E = 14 GPa; EI ZZ represents the section flapping stiffness, EI YY Represents the section shimmy stiffness.

[0096] like Figure 6 As shown in the figure, after the stiffness characteristics of each structural section of the blade are calculated according to the rectangular unit, the blade section is discretized into multiple section segments from the blade root to the blade tip along the span direction according to the equidistant method. The stiffness is represented in the form of logarithmic coordinates, and the flapping stiffness and shimmy stiffness distributed along the blade span direction are obtained by scatter point fitting.

[0097] like Figure 7 As shown, the full-size blade is simplified into discrete sections, and the curvature of the s-th section is calculated based on the section bending moment, flapping stiffness, and shimmy stiffness. s=1,2…L,L is defined as the maximum number of discrete sections along the blade span direction; where M y is the flapping bending moment around the y-axis of the flapping vibration coordinate system, M z is the shimmying bending moment about the z-axis of the flapping shimmying coordinate system.

[0098] Calculate the curvature of the sth section and

[0099] By integrating the rotation angle and deformation equations of the discrete blade section, we can obtain the numerical algorithm for deformation. The specific algorithm is as follows:

[0100] (1) The boundary condition is defined as the first blade root section as well as The cumulative rotation angle of the blade section is calculated as: and Where x is the discrete cross-sectional length of the blade, x s is the length of the sth blade section, x L is the total span length of the blade.

[0101] (2) The boundary condition is defined as the first blade root section and The cumulative deformation of the blade section is calculated as and

[0102] like Figure 8 As shown in the figure, the blade section is discretized into multiple section segments from the blade root to the blade tip along the span direction according to the equidistance method, and the tip deformation in the flapping direction and the tip deformation in the swing direction along the blade span direction are obtained by scatter point fitting.

[0103] like Figure 9As shown in the figure, a series of repair specimens were prepared in the laboratory, and multiple repair parameters were defined as overlap width, number of overlap surfaces, number of reinforcement layers, and overlap method. The specimens were unidirectional boards, and the fiber reinforcement material selected was China Taishan CTG-EUL1200(0), and the matrix was HEXION epoxy resin LR235. Rectangular specimens were prepared by vacuum bagging according to ISO 527-5. Considering the discreteness of the data, the number of valid specimens in each test specimen group was at least 3.

[0104] Next, the specimens were one-way boards. The fiber reinforcement material selected was China Taishan CTG-EUL1200(0), and the matrix was HEXION epoxy resin LR235. Rectangular specimens were prepared using the vacuum bagging method according to ISO 527-5. The prepared specimens were 420-600 mm in length, 50 mm in width, 80 mm and 100 mm in overlap width, 1, 2 and 3 overlap surfaces, 0, 1 and 2 reinforcement layers, double overlap and single overlap, and single-sided and double-sided reinforcement methods. The specimen specifications were as follows:

[0105] Table 1 Design, repair and configuration parameters of repair specimens

[0106]

[0107] like Figure 10 As shown, all specimens underwent tensile testing using an MTS809 electro-hydraulic servo materials testing machine with an axial testing range of ±25 tons and an axial dynamic displacement of ±100 mm. Displacement-controlled quasi-static loading was employed during the test, with the end grip moving at a speed of 1 mm / min and applying axial tensile load uniformly until the specimen failed. Data acquisition was performed using BE120-3AA strain gauges manufactured by AVIC Electro-Mechanical and a JM3840 dynamic and static strain measurement system manufactured by Yangzhou Jingming Technology Co., Ltd., which includes eight acquisition channels and a continuous sampling rate of 100 Hz / channel. Prior to the actual testing, the strain sensors were calibrated on the materials testing machine to ensure accuracy. Strain gauges were placed in the stepped overlap area, the motherboard, and the patch locations, depending on the specimen specifications.

[0108] By statistically analyzing the tensile test performance of the repaired specimens, the influence of the quantitative combination of multiple repair parameters on the overall failure load of the specimens was verified. The test results are detailed in Table 2. The values ​​given in the table are the average values ​​of each group of valid specimens.

[0109] Table 2 Tensile test strength properties of repaired specimens

[0110]

[0111] like Figure 11According to the test process, the tensile stress-strain curves of the specimens obtained from different test schemes were drawn, and the influence of the quantitative matching scheme of multiple repair parameters on the turning point of the repair stiffness was obtained.

[0112] Next, the repair cost C is calculated based on the quantitative combination of multiple repair parameters. rep , C rep =C m +C r +C0, where C m is the cost of repair materials, C r C0 is the labor cost for repair and the scheduling cost. These costs are realized as follows:

[0113] (1) Repair costs p=1,2…D, D is the total number of types of restoration materials used, M p is the amount of material p, Q p is the unit price of the pth material.

[0114] (2) Calculate the repair labor cost C based on the repair method (repair on the tower, repair below the tower), the number of repair labor hours, and the cost per repair laborer per hour. r =T*F*H, see Table 3 for calculation method.

[0115] Table 3 Calculation method of repair labor cost

[0116]

[0117] (3) Define the dispatch cost C0=C1+C2 in a repair manner. The calculation method is shown in Table 4;

[0118] Table 4 Repair scheduling costs and other costs

[0119]

[0120] Next, calculate the ratio of repair cost to blade manufacturing cost Where C blade The manufacturing cost of the blade.

[0121] like Figure 12 As shown in the figure, the four repair decisions for blade main beam delamination damage are defined as no repair, repair on the tower, repair below the tower, and scrapping.

[0122] The repair decision model is defined by piecewise function expression, and the piecewise function F = f(k′) is defined as follows: Where C blade is the manufacturing cost of the blade, which is a fixed value according to the blade model.

[0123] When 0≤k′<0.5%, F=0; when 0.5%≤k′<10%, When 10%≤k′<20%, ​​F=0.5(k-10%)+10%; when k′≥20%, F=2(k-20%)+30%.

[0124] Finally, a piecewise function method is used to establish a quantitative repair decision model.

[0125] The present invention:

[0126] 1. In view of the current lack of evaluation on the impact of wind turbine blade main beam delamination on the blade section stiffness structural characteristics, a method for calculating the section flapping stiffness and shimmy stiffness by layer-by-layer rectangular unit sampling of the blade section is proposed to achieve a quantitative description of the impact of main beam delamination on stiffness.

[0127] 2. In view of the lack of quantitative judgment basis for the severity of the impact of main beam delamination damage on blades in the current repair decision expression model, a quantitative calculation method for the deformation of the full-size blade tip caused by main beam delamination damage is proposed to achieve accurate calculation of the severity of main beam delamination.

[0128] 3. In view of the fact that the current repair decision expression model cannot accurately and quantitatively calculate the repair cost, the repair cycle and the total amount of repair materials are intuitively evaluated based on the quantitative combination of repair parameters. A repair cost calculation method based on the repair material cost, repair labor cost and scheduling cost is proposed to achieve quantitative calculation of the repair cost.

[0129] 4. The current repair decision-making method for wind turbine blade main beam delamination damage ignores the impact of delamination-induced stiffness degradation on blade tip deformation and the quantitative repair cost calculation method, resulting in a lack of guidance for the implementation of main beam delamination damage repair. An algorithm is proposed to establish a quantitative piecewise function expression model of the coupling relationship between the blade tip deformation caused by blade main beam delamination damage and the repair cost, thereby reducing the wind power operation and maintenance cost and providing guidance for the repair of blade main beam delamination damage.

[0130] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effects; as long as the use requirements are met, they are within the scope of protection of the present invention.

Claims

1. A quantitative repair decision-making method for delamination damage of a wind turbine blade main beam, characterized by: include: Step 1: For the delamination damage of the main beam of the wind turbine blade, a rectangular unit of the blade cross-section ply structure is established to calculate the cross-section stiffness structural characteristics; Step 2: Establish a quantitative calculation method for the influence of blade main beam delamination damage on the deformation of the full-size blade tip; Step 3: Establish a test research method for quantitative matching of multiple restoration parameters and calculate the restoration cost; Step 4: Establish a piecewise function expression model for restoration decision-making and determine four quantitative methods for restoration decision-making; The quantitative calculation method for establishing the influence of blade main beam delamination damage on the deformation of full-scale blade tip includes: Step 2.1, calculate the curvature of the sth section based on the section bending moment, flapping stiffness, and shimmy stiffness: It is defined as the maximum number of discrete sections along the blade span direction; where M y is the flapping bending moment around the y-axis of the flapping vibration coordinate system, M z is the shimmying bending moment about the z-axis of the flapping shimmying coordinate system; Step 2.2, calculate the curvature of the sth section: Where β is the twist angle of the section chord length relative to the blade tip chord length; Step 2.3, the cumulative rotation angle of the blade section is calculated as: Where, the first blade root section and x is the discrete cross-sectional length of the blade, x s is the length of the sth blade section, x L is the total span length of the blade; In step 2.4, the cumulative deformation of the blade section is calculated as: Where, the first blade root section and The step 3 includes: Step 3.1: Prepare multiple sets of one-way slab repair specimens with a specimen length of 420-600 mm, a specimen width of 50 mm, a lap width of 80 mm and 100 mm, a number of lap surfaces of 1, 2, and 3, a number of reinforcement layers of 0, 1, and 2, a lap method of double lap and single lap, and a reinforcement method of single-sided and double-sided. The specimen specifications are as follows: Step 3.2: Tensile tests were conducted on all specimens. Strain gauges were placed in the stepped overlap area, the motherboard, and the patch location according to the different specimen specifications. The tensile test performance of the repaired specimens was statistically analyzed to verify the influence of the quantitative combination of multiple repair parameters on the overall failure load of the specimens, which was determined by the experiments. Step 3.3, the tensile stress-strain curve of the specimen obtained by the test is used to obtain the influence of the multi-repair parameter quantitative matching scheme on the repair stiffness turning point, and the repair cost C is calculated by the multi-repair parameter quantitative matching scheme. rep : C rep =C m +C r +C0 Where C m is the cost of repair materials, C r is the repair labor cost, C0 is the scheduling cost; Repair costs D is the total number of types of repair materials used, M p is the amount of material p, Q p is the unit price of the pth material; Assume that the repair method is A = [1, 2], where A = 1 represents the repair on the tower, and A = 2 represents the repair below the tower; the repair labor cost C r =T*F*H, where T is the maximum number of hours for repair, F is the number of repair workers, and H is the labor cost for repair; when A=1, T=48, F=2, H=200; when A=2, T=120, F=6, H=800; Scheduling cost C0 = C1 + C2, when A = 1, C1 = 2000, C2 = 2000, when A = 2, C1 = 100000, C2 = 20000; The step 4 comprises: Step 4.1, define the four repair decisions for blade main beam delamination damage as no repair, repair on the tower, repair below the tower, and scrapping; Step 4.2: Define the repair decision model using piecewise function expression. Let piecewise function F = f(k′), where Where C blade is the manufacturing cost of the blade, which is a fixed value according to the blade model; Step 4.3, when 0≤k′<0.5%, F=0; when 0.5%≤k′<10%, When 10%≤k′<20%, F=0.5(k-10%)+10%; when k′≥20%, F=2(k-20%)+30%; Step 4.4: Use piecewise function method to establish a quantitative repair decision model.

2. The method according to claim 1, wherein: The delamination of the wind turbine blade main beam delamination damage is located between or on the surface of the blade main beam laminate. The geometric characteristics of the delamination are defined as the delamination span position, delamination width and delamination depth. The plies in the delamination area do not participate in the calculation of structural characteristics.

3. The method according to claim 1, wherein: The calculated section stiffness structural characteristics include: Step 1.1: The blade structure cross-section is an airfoil shape. The airfoil geometry is discretized into 200 coordinate points using the equal division method to calculate the ply stiffness characteristics. Step 1.2: Use two adjacent geometric coordinate points of the airfoil section as the length of the rectangular unit, use h1 to represent the thickness of the first skin layer and define it as the i-th rectangular unit, i = 1, 2...N, N is defined as the maximum number of units in the section, divide the airfoil section into 200 coordinate points, and sample N = 199 rectangular units. Define the angle θ between the long side of the rectangular unit and the chord length direction of the section; At this time, the coordinates of the point ABCD of the i-th rectangular unit are D(Z[i],Y[i]),C(Z[i+1],Y[i+1]),A(Z'[i],Y'[i]),B(Z'[i+1],Y'[i+1]); Among them, the coordinates of vertices C and D are directly extracted from the geometric shape of the airfoil section; The coordinates of the vertex A of the rectangular unit are calculated as Z'[i]=Z[i]-h1*cosθ, Y'[i]=Y[i]+h1*sinθ, The coordinates of vertex B are calculated as Z'[i+1]=Z[i+1]-h1*cosθ, Y'[i+1]=Y[i+1]+h1*sinθ; Step 1.3, calculate the second-order moment of inertia of the rectangular element with respect to the flapping coordinate system: Where, ΔZ'=h1*cosθ, ΔY'=h1*sinθ; Step 1.4: Calculate the second-order moment of inertia of the first skin layer: The algorithm for the rectangular elements of other layers is the same as that for the first layer of skin. Step 1.5: Calculate the structural stiffness EI of the blade section ZZ =∑(E j I ZZj ), EI YY =∑(E j I YYj ), where j represents the jth material in the blade structure, j = 1, 2…M, and M is defined as the maximum number of materials selected for the section; E j is the elastic modulus of the j material in the fiber direction, such as epoxy 0° unidirectional fabric E = 40 GPa, ±45 / 0° epoxy triaxial fabric E = 28 GPa, ±45° epoxy biaxial fabric E = 14 GPa; EI ZZ represents the section flapping stiffness, EI YY Represents the section shimmy stiffness.

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