Honeycomb structure and wind turbine blade

Abstract

The utility model relates to a honeycomb structure body and wind power blade, the honeycomb structure body comprises a honeycomb wall, the honeycomb wall comprises a first fiber and a second fiber, an included angle theta is formed between the first fiber and the thickness direction of the honeycomb structure body, an included angle-theta is formed between the second fiber and the thickness direction of the honeycomb structure body, and theta is larger than 0 degree and smaller than 90 degrees. The wind power blade comprises the honeycomb structure body. The honeycomb structure disclosed by the utility model has excellent shear modulus and very light specific gravity, and can be used as a core material of a large-sized wind power blade, so that the large-sized wind power blade with high spanwise shear strength and excellent bending resistance can be manufactured.

Description

Technical Field

[0001] The utility model relates to a honeycomb structure and a wind power blade. Background Art

[0002] As a clean energy with huge energy, wind energy is increasingly valued by countries around the world. Wind turbines are the main equipment for generating electricity using wind energy. Their structure includes an impeller composed of several wind turbine blades. When the wind blows towards the wind turbine blades, the wind turbine blades drive the impeller to rotate and prompt the generator to generate electricity. In order to increase the "wind-catching ability" of the blades, increase the power of the generator and reduce costs, the development trend of "large-scale" blades is becoming increasingly clear. Data show that in 2020, the average unit capacity of onshore wind turbines used in China's newly installed capacity was only about 2.6 megawatts, and the average unit capacity of offshore wind turbines was about 4.8 megawatts. In the newly installed capacity in 2022, the average unit capacity of onshore wind turbines has reached 4.2 megawatts, and the average unit capacity of offshore wind turbines has exceeded 7.4 megawatts, with a year-on-year increase of more than 30%. In terms of offshore wind power, units with a unit capacity of 15 megawatts or more are common. In terms of impeller diameter, the maximum impeller diameter of offshore wind turbines has reached 280 meters. However, the process of scaling up wind turbine blades is currently constrained by both materials and costs.

[0003] In terms of materials, the materials used to make wind turbine blades need to be light and have good structural rigidity and strength. This is mainly because when the wind turbine is working, the wind turbine blades need to withstand the pressure generated by the wind load on the one hand, which mainly acts on the front of the wind turbine blades and forces the wind turbine blades to deform in the span direction; on the other hand, the wind turbine blades also need to withstand the stress generated by their own weight, especially when the wind turbine blades rotate clockwise after 6 points, the trailing edge sandwich structure close to the root is significantly increased in spanwise compression stress, which is prone to local instability and causes the blades to buckle and fail.

[0004] In order to reduce the weight as much as possible while ensuring the mechanical strength, a sandwich structure is generally used at the leading edge 110, the trailing edge 120 and the shear rib 130 of the blade (see Figure 6 ). The sandwich structure is mainly composed of plies and lightweight core materials between the plies. As the length of the blade increases, the overall weight increases, and the lightweight core material becomes particularly important. The core materials currently used are generally balsa, PVC foam and PET foam. The mechanical properties that can be achieved can be referred to the following table:

[0005] Test items PVC60 PET100 PET150 Basa wood <![CDATA[Density (kg / m 3 )]]> 60 95-120 140-160 135-170 Compression strength(MPa) 0.6 1.2 2.2 6 Compression modulus (MPa) 55 65 85 2000 Shear strength(MPa) 0.6 0.6 0.6 1.8 Shear modulus (MPa) 20 26 28 160

[0006] As the size of wind turbine blades increases, the performance of the above materials becomes inadequate.

[0007] On the other hand, in terms of cost, wind turbine blades are products that are highly dependent on raw materials, and the cost of raw materials accounts for about 80% of the production cost of blades. The cost of core materials accounts for about 10-20% of the material cost of wind turbine blades, which is the main expenditure part of the blade cost. The thickness of the core material gradually decreases from the root of the blade to the tip of the blade. Light wood with relatively high shear strength and modulus is usually used to bear the larger load near the root of the blade, and foam core material is used to bear the relatively smaller load near the tip of the blade. As the length of the blade continues to increase, the proportion of light wood in the core material of the entire blade structure has gradually increased from the original 30% to 50%, and the proportion of light wood in blades with a length of more than 100 meters has exceeded 75%.

[0008] Balsa is a natural wood of the Bombax family. It usually takes 4-5 years for mature trees to mature, and its production is limited worldwide. As a natural product, the mechanical properties of balsa are easily affected by the growth environment, and there are large differences between individuals. The structural core material of balsa wood used for wind turbine blades must be strictly screened and go through multiple processes such as drying, sterilization, splicing, slicing and surface treatment, which further reduces the actual output of wind turbine blade core materials made of balsa wood. In 2018, the average price of balsa wood was around 5,800 yuan per cubic meter; in 2019, it rose to around 7,800 yuan per cubic meter; in 2020, with the booming wind power industry, balsa wood is comparable to gold, and its price has doubled to 15,000-16,000 yuan per cubic meter.

[0009] It can be seen that the mechanical properties and cost of the material seriously affect the pace of blade size expansion.

[0010] Honeycomb materials, as a low-density composite material, have been widely used in the aerospace industry. They have the advantages of low density and stable pressure resistance, but their performance cannot meet the requirements of wind turbine blades. Traditional honeycomb technology can only increase the mechanical properties of the honeycomb by reducing the honeycomb diameter. Obviously, this approach will increase the weight of the honeycomb material and cannot meet the lightweight requirements of the blade core material. In addition, during the process of vacuum resin introduction into wind turbine blades, the gap between the honeycomb and the filler and the porous nature of the filler itself will absorb more resin, further increasing the weight of the blade. Utility Model Content

[0011] One of the main purposes of the utility model is to provide a honeycomb structure with excellent mechanical strength.

[0012] The second main purpose of the utility model is to provide a honeycomb structure with excellent spanwise shear strength and effective chordwise conformability, so as to replace the existing balsa wood as the core material of the wind blade.

[0013] In order to achieve at least one of the above purposes, the first aspect of the utility model provides a honeycomb structure, including a honeycomb wall, wherein the honeycomb wall comprises first fibers forming an angle θ with the thickness direction of the honeycomb structure, and second fibers forming an angle -θ, wherein θ is greater than 0° and less than 90°.

[0014] In some embodiments of the first aspect of the present invention, the angle θ is 45°.

[0015] In some embodiments of the first aspect of the present invention, the housing further comprises a housing hole, wherein the housing hole is filled with a filling body of a hard elastic closed-cell foam material.

[0016] In some embodiments of the first aspect of the present invention, the rigid elastic closed-cell foam material is a closed-cell polyurethane foam or a closed-cell PET foam.

[0017] In some embodiments of the first aspect of the present invention, the honeycomb wall comprises a first sub-honeycomb wall of a corrugated structure and a second sub-honeycomb wall of a planar structure, and the first sub-honeycomb wall and the second sub-honeycomb wall are alternately stacked to form the honeycomb wall.

[0018] In some embodiments of the first aspect of the present invention, at least the first sub-honeycomb wall contains the first fibers and the second fibers.

[0019] In some embodiments of the first aspect of the present invention, the corrugated structure of the first sub-honeycomb wall is isosceles trapezoidal grooves that are alternately opposed, and isosceles trapezoidal cells are formed between the first sub-honeycomb wall and the second sub-honeycomb wall.

[0020] In some embodiments of the first aspect of the present invention, the base angle of the isosceles trapezoid is less than 85°, and the length of the upper base is greater than 10 mm.

[0021] In some embodiments of the first aspect of the present invention, the honeycomb wall is formed by curing a fiber cloth impregnated with a resin system.

[0022] In some embodiments of the first aspect of the present invention, the fiber cloth is a biaxial fiber cloth with a [45° / -45°] ply or a triaxial fiber cloth with a [0° / 45° / -45°] ply.

[0023] In some embodiments of the first aspect of the present invention, the first fiber and the second fiber are respectively selected from carbon fiber, graphite fiber, glass fiber or basalt fiber.

[0024] A second aspect of the utility model relates to a wind turbine blade, comprising any of the honeycomb structures described above.

[0025] In some embodiments of the second aspect of the present invention, the honeycomb structure is used for the sandwich structure of the leading edge, trailing edge and / or shear rib of a wind turbine blade.

[0026] The honeycomb structure of the utility model has excellent shear modulus and very light specific gravity, and can be used as the core material of large wind blades, making it possible to manufacture large-sized wind blades with high spanwise shear strength and excellent anti-bending performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the fiber direction of the triaxial fiber cloth.

[0028] Figure 2 It is a schematic diagram of the three-dimensional structure of the first sub-honeycomb wall made of triaxial fiber cloth.

[0029] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure of the first sub-honeycomb wall.

[0030] Figure 4 Schematic diagram of the cross-sectional structure of a honeycomb structural unit.

[0031] Figure 5 Schematic diagram of the manufacturing process of the honeycomb structure.

[0032] Figure 6 Schematic diagram of the cross-sectional structure of a wind turbine blade.

[0033] Figure 7 It is a schematic diagram of the structure of an existing honeycomb structure.

[0034] Figure 8 Schematic diagram of the structure of the honeycomb structure in the embodiment.

[0035] In the figure: 1-first fiber, 2-second fiber, 3-third fiber, 10-first sub-honeycomb wall, 11 and 12 are two trapezoidal grooves arranged alternately opposite to each other, 20-second sub-honeycomb wall, 30-filling body, 31-upper bottom, 32-lower bottom, 40-cell hole, a represents the length of the upper bottom of the trapezoid, b represents the length of the lower bottom of the trapezoid, h represents the height of the trapezoid, and w represents the thickness of the honeycomb. DETAILED DESCRIPTION

[0036] Unless otherwise defined, the technical and scientific terms used herein have the same meanings as those commonly understood by one of ordinary skill in the art. In the event of a conflict, the descriptions and definitions herein shall prevail.

[0037] In the related embodiments of the prior art, the honeycomb structure includes a series of regular hexagonal and quadrilateral cells formed by honeycomb walls. Figure 7The regular hexagonal pores 40 are closely arranged and extend in the thickness direction w of the honeycomb structure. The honeycomb wall 10 contains composite reinforcing fibers interwoven at 90° and 0° with the thickness direction w. The honeycomb structure formed by such a honeycomb wall has a low shear modulus. When the shear modulus needs to be increased, the pore diameter needs to be reduced, but at this time the lightweight advantage of the honeycomb structure itself will be lost and it cannot be used as a manufacturing material for wind turbine blades.

[0038] In view of the defects in the above-mentioned embodiments, the utility model provides a honeycomb structure to further improve the shear modulus of the honeycomb structure. The honeycomb wall in the honeycomb structure contains a first fiber at an angle θ with the thickness direction of the honeycomb structure, and a second fiber at an angle -θ, wherein θ is greater than 0° and less than 90°. The utility model has found that when there are fibers in the honeycomb wall that obliquely intersect with the thickness direction of the honeycomb structure, the shear modulus of the honeycomb structure can be improved. The inventor believes that this is because under pure shear conditions, tensile and compressive stresses in the direction of 45° / -45° will appear inside the honeycomb structure, so the closer the inclination angle is to 45°, the more obvious the increase in shear modulus. This avoids the need for the prior art to adjust the shear modulus of the honeycomb structure by reducing the aperture of the room pores, so that the honeycomb structure can improve its own shear modulus without reducing the aperture, or even by expanding the aperture, thereby reducing the weight of the honeycomb structure, so that the honeycomb structure can be used as the core material of wind turbine blades.

[0039] The method for manufacturing the honeycomb wall containing the above-mentioned fibers can be to form the honeycomb wall by adding the above-mentioned fibers into the resin at a required angle and then curing it, or directly using the fiber cloth manufactured at the required fiber angle, impregnating the fiber cloth with resin and then curing it to form the honeycomb wall.

[0040] Furthermore, the present invention has found that when the angle θ reaches 45°, that is, when the first fiber and the second fiber are at an angle of 45° and -45° with the thickness direction of the honeycomb structure, the shear modulus of the honeycomb structure can be maximized. This is because under pure shear conditions, tensile and compressive stresses in the direction of 45 / -45 degrees will appear inside the honeycomb structure, so the closer the inclination angle is to 45 degrees, the more obvious the increase in shear modulus.

[0041] The cells in the honeycomb structure are also filled with a filling body of a hard elastic closed-cell foam material, and the hard elastic closed-cell foam material has a compressibility of more than 5%. The hard elastic closed-cell foam has a compressibility of more than 5%, and can effectively fill the gaps in the cells through interference filling. The closed-cell foam material is used to ensure that the vacuum resin introduction process in the manufacture of wind turbine blades will not cause the problem of excessive weight due to excessive resin absorption by the foam holes when used as the core material of wind turbine blades. According to the requirements of the utility model for compression capacity, various hard elastic closed-cell foam materials that meet the requirements can be selected as needed, and the closed-cell process is known to technicians in the field. The utility model preferably uses closed-cell polyurethane foam or closed-cell PET foam. The closed-cell polyurethane foam or closed-cell PET foam can better cooperate with the honeycomb wall structure of the utility model to improve the overall mechanical properties of the honeycomb structure. In addition, the closed-cell polyurethane foam or closed-cell PET foam can also withstand the model temperature in the wind turbine blade molding process.

[0042] The honeycomb wall includes a first sub-honeycomb wall of a corrugated structure and a second sub-honeycomb wall of a plane structure, and the first sub-honeycomb wall and the second sub-honeycomb wall are alternately stacked. In one specific structure, the corrugated structure of the first sub-honeycomb wall is a plane that alternates on both sides of the extension direction and an inclined plane that transitions between adjacent planes on both sides. The planes on both sides and the inclined planes connected thereto form a groove structure, and the groove structure is covered by the second sub-honeycomb to form a complete cell. The method of alternately stacking the first and second sub-honeycomb walls can effectively simplify the production process. On the other hand, this stacking structure can realize unitized production and ultimately improve production efficiency. The above production method can produce most of the honeycomb structures and cell structures. For example, when it is necessary to produce a honeycomb structure with regular hexagonal cells, it can also be achieved by splicing two isosceles trapezoidal cell structures. Functionally, the second sub-honeycomb wall plays the role of bonding the first sub-honeycomb wall on the one hand, and on the other hand, it can also improve the strength of the honeycomb structure.

[0043] The corrugated structure of the first sub-honeycomb wall is preferably isosceles trapezoidal grooves that are alternately opposed. Figures 2 to 4 As shown, there are isosceles trapezoidal grooves 11 and 12 on both sides of the first sub-honeycomb wall 10, and then isosceles trapezoidal cells are formed between the first sub-honeycomb wall and the second sub-honeycomb wall. The base angle of the isosceles trapezoid is preferably less than 85°. When the honeycomb structure is subjected to vertical (reference Figure 4When the honeycomb corrugated sheet is compressed vertically, sufficient restraining force can be generated in the horizontal direction to keep the side wall of the honeycomb corrugated sheet and the filling body in close contact. Any gap between the honeycomb side wall and the hard elastic closed-cell foam will affect the amount of glue absorbed by the wind turbine blade during the vacuum resin introduction molding process. Honeycombs with inconsistent glue absorption may also cause inconsistent weights of multiple blades of a single wind turbine and lead to eccentricity. Furthermore, the length of the trapezoidal upper base a is preferably greater than 10 mm, which is convenient for selecting large-sized foam and reducing the number of times the foam is laid.

[0044] The honeycomb wall is formed by curing a fiber cloth impregnated with a resin system. The fiber cloth is a biaxial fiber cloth with a [45° / -45°] ply or a triaxial fiber cloth with a [0° / 45° / -45°] ply. The triaxial fiber cloth has a surface weight of ≥600g / m 2 , biaxial fiber cloth surface weight ≥450g / m 2 , in order to further improve the strength of the honeycomb structure. The distribution of each fiber in the triaxial fiber cloth can be referred to Figure 1 The triaxial fiber cloth used to manufacture the first sub-honeycomb wall is formed by three-way interweaving of the first fiber 1 at an angle of 45° to the thickness direction of the honeycomb structure, the second fiber 2 at an angle of -45°, and the third fiber 3 at an angle of 0° (i.e. parallel to the thickness direction). The biaxial fiber cloth can be formed by bidirectional interweaving of the first fiber at 45° and the second fiber at -45°. The fiber cloth used to manufacture the second sub-honeycomb wall can also be formed by bidirectional interweaving of 0° and 90°.

[0045] Preferably, the curing temperature of the resin system is 45 to 110°C. The operation of epoxy resin with a curing temperature higher than 110°C is somewhat difficult. On the one hand, most foams are easy to melt or decompose at this temperature. On the other hand, since the foam material is a poor conductor of heat, the temperature rise inside the honeycomb product is limited. Too high a curing temperature will result in incomplete curing of the product. Any usable resin system can be selected according to the curing temperature. The utility model preferably contains an imidazole curing agent and a volatile solvent resin system. The selected resin includes but is not limited to unsaturated resins, vinyl resins, epoxy resins or benzoxazine resins. The volatile solvent can be completely volatilized at the curing temperature, and many tiny openings connected in series will be generated inside the epoxy resin; when the vacuum resin introduction process of the entire blade is formed, these small holes can allow other types of epoxy resins to enter the micropores at atmospheric pressure, thereby increasing the bonding compatibility. The resin system preferably contains imidazole, anhydrous alcohol and bisphenol A epoxy resin. In one specific ratio, the ratio of imidazole to anhydrous alcohol is less than 1:1, the ratio of imidazole to bisphenol A epoxy resin is between 1:100 and 5:100, and the ratio of anhydrous alcohol to bisphenol A epoxy resin is above 1:10. The curing time of the resin system is 3 hours at 50°C, which can be shortened to 15 minutes at 110°C, but the operating time at room temperature of 25°C can be as long as more than 24 hours. This epoxy resin system is compatible with various foams such as polystyrene foam, polyurethane foam, PVDF, etc., does not react or dissolve, and has good bonding ability with each other after curing. When anhydrous alcohol is used as a volatile solvent, the honeycomb structure can also be produced without odor. When the alcohol solvent is completely volatilized during curing, many tiny openings connected in series will be generated inside the epoxy resin; when the vacuum resin introduction process of the integral blade is formed, these small holes can allow various other types of epoxy resins to enter the micropores under atmospheric pressure, thereby increasing the bonding compatibility.

[0046] The first and second fibers are continuous fiber reinforced composite materials, including but not limited to carbon fiber, graphite fiber, glass fiber, and basalt fiber.

[0047] In addition, the utility model also provides a method for manufacturing a honeycomb structure, including the steps of making a honeycomb wall, wherein the honeycomb wall comprises a first fiber at an angle θ with the thickness direction of the honeycomb structure and a second fiber at an angle -θ, wherein θ is greater than 0° and less than 90°. Similar to the above, when the first fiber that is not oblique to the thickness direction of the honeycomb structure exists in the preparation of the honeycomb wall, the shear modulus of the honeycomb structure can be improved. When the θ is 45°, the shear modulus of the honeycomb structure can be maximized.

[0048] The honeycomb wall includes a first sub-honeycomb wall of a corrugated structure and a second sub-honeycomb wall of a plane structure, and the first sub-honeycomb wall and the second sub-honeycomb wall are alternately superimposed to form the honeycomb wall and the cell. In one specific structure, the corrugated structure of the first sub-honeycomb wall is a plane that alternates on both sides of the extension direction and an inclined plane that transitions between adjacent planes on both sides. The planes on both sides and the inclined planes connected thereto form a groove structure, and the groove structure is covered by the second sub-honeycomb to form a complete cell. The method of alternately superimposing the first and second sub-honeycomb walls can effectively simplify the production process. On the other hand, this superimposed structure can realize unitized production and ultimately improve production efficiency. The above production method can produce most of the honeycomb structures and cell structures. For example, when it is necessary to produce a honeycomb structure with regular hexagonal cells, it can also be achieved by splicing two isosceles trapezoidal cell structures. The second sub-honeycomb wall, on the one hand, plays a role in bonding the first sub-honeycomb wall, and on the other hand, it can also improve the strength of the honeycomb structure. Specifically, it may include the steps of: dip-coating a resin system on the surface of a plurality of first fiber cloths and second fiber cloths, and the first fiber cloths contain the first fibers and the second fibers. A plurality of fillers are manufactured according to the shape of the cell pores, and the fillers are alternately bonded to both sides of the first fiber cloth to manufacture a honeycomb structure unit, and the first fiber cloth is bent along the contour of the filler to form a corrugated structure. A plurality of honeycomb structure units are alternately stacked with a second fiber cloth dipped in a resin system to obtain a honeycomb structure precursor. The honeycomb structure precursor is cured to obtain a honeycomb structure.

[0049] In the above preparation process, the first sub-honeycomb wall or the second sub-honeycomb wall is not separately made by resin curing, but the precursor of the sub-honeycomb wall to be cured is made by dipping resin, and these precursors are superimposed and finally formed into a honeycomb wall containing the first and second sub-honeycomb walls by heating and curing together. Compared with the method of separately making and curing them, or making them into honeycomb unit structures and then bonding and curing them for the second time, the co-curing of the utility model can significantly reduce the amount of resin system used, thereby further reducing the gram weight of the honeycomb structure.

[0050] The corrugated structure of the first sub-honeycomb wall is an isosceles trapezoidal groove that alternates in opposite directions. Figure 2 As shown, an isosceles trapezoidal cell is formed between the first sub-honeycomb wall and the second sub-honeycomb wall. The bottom angle of the isosceles trapezoid is preferably less than 85°, so that sufficient lateral restraint can be generated during vertical compression, so that the side wall of the honeycomb corrugated sheet and the foam are in closer contact. The upper bottom length is preferably greater than 10 mm, which is convenient for selecting large-sized foam, reducing the number of foam laying times, and increasing production efficiency.

[0051] The honeycomb wall is a fiber cloth covered with a cured resin. The fiber cloth used is a biaxial fiber cloth with a [45° / -45°] layer or a triaxial fiber cloth with a [0° / 45° / -45°] layer. The triaxial fiber cloth has a surface weight of ≥600g / m 2 , biaxial fiber cloth surface weight ≥450g / m 2 , to further improve the strength of the honeycomb arm.

[0052] Preferably, the curing temperature of the resin system is 50-110°C. Any usable resin system can be selected according to the curing temperature. The utility model preferably contains a resin system containing an imidazole curing agent and a volatile solvent. The selected resin includes but is not limited to an unsaturated resin, a vinyl resin, an epoxy resin or a benzoxazine resin. The volatile solvent can be completely volatilized at the curing temperature, and many tiny openings connected in series will be generated inside the epoxy resin; when the vacuum resin introduction process of the whole blade is formed, these small holes can allow other types of epoxy resins to enter the micropores under atmospheric pressure, thereby increasing the bonding compatibility. The resin system contains imidazole, anhydrous alcohol and bisphenol A epoxy resin. In one specific ratio, the ratio of imidazole: anhydrous alcohol is less than 1:1, the ratio of imidazole: bisphenol A epoxy resin is between 1:100 and 5:100, and the ratio of anhydrous alcohol: bisphenol A epoxy resin is above 1:10. The resin curing time of this resin system is 3 hours at 50°C, which can be shortened to 15 minutes at 110°C, but the operating time at room temperature of 25°C can be as long as more than 24 hours. This epoxy resin system is compatible with various foams such as polystyrene foam, polyurethane foam, PVDF, etc., does not react or dissolve with each other, and has good bonding ability with each other after curing. Since anhydrous alcohol is used as a solvent, honeycomb production is environmentally friendly and odorless. When the alcohol solvent is completely volatilized during curing, many tiny openings connected in series will be generated inside the epoxy resin; when the vacuum resin introduction process of the entire blade is formed, these small holes can allow various other types of epoxy resins to enter the micropores under atmospheric pressure, thereby increasing bonding compatibility.

[0053] The first fiber and the second fiber are continuous fiber reinforced composite materials, including but not limited to one or more of carbon fiber, graphite fiber, glass fiber, and basalt fiber.

[0054] The filler in the honeycomb structure is a hard elastic closed-cell foam material, and the hard elastic closed-cell foam material has a compressibility of more than 5%. Through interference filling, the gaps in the pores can be effectively filled. The closed-cell foam material is used to ensure that the vacuum resin introduction process in the manufacture of wind turbine blades will not cause the problem of excessive weight due to excessive resin absorption by the foam holes when used as the core material of wind turbine blades. According to the requirements of the present invention for compression capacity, various hard elastic closed-cell foam materials that meet the requirements can be selected as needed, and the closed-cell process is known to technicians in this field. The present invention preferably uses closed-cell polyurethane foam or closed-cell PET foam. Closed-cell polyurethane foam or closed-cell PET foam can better cooperate with the honeycomb wall structure of the present invention to improve the overall mechanical properties of the honeycomb structure. In addition, closed-cell polyurethane foam or closed-cell PET foam can also withstand the model temperature in the wind turbine blade molding process.

[0055] Finally, the utility model also relates to a wind turbine blade, the interlayer of which adopts the aforementioned honeycomb structure, or adopts the honeycomb structure manufactured by the aforementioned manufacturing method. Preferably, the honeycomb structure is used for the interlayer structure of the leading edge, trailing edge and / or shear rib of the wind turbine blade. The manufactured wind turbine blade has the advantages of lighter weight and better mechanical properties.

[0056] The present invention is further described below in conjunction with specific embodiments.

[0057] Example 1 Preparation of a medium temperature curing resin system

[0058] Mix solid imidazole and anhydrous alcohol in a ratio of less than 1:1, and stir thoroughly at 10-30°C to completely dissolve the solid imidazole in the anhydrous alcohol.

[0059] Heat bisphenol A epoxy resin to 30-45°C.

[0060] The anhydrous alcohol dissolved with imidazole and the bisphenol A epoxy resin are fully mixed at 30-45°C, and the ratio of imidazole to bisphenol A epoxy is controlled between 1:100 and 5:100; the ratio of anhydrous alcohol to epoxy resin is controlled to be above 1:10.

[0061] The curing temperature of the prepared resin system is between 50 and 110°C.

[0062] Examples 2 to 4: Manufacturing of Honeycomb Structures

[0063]

[0064] Reference Figure 5 The steps in the figure are shown to manufacture a honeycomb structure:

[0065] Step i, provide a first fiber cloth and a second fiber cloth according to the above table, and dip-coat the surfaces of the first and second fiber cloths with the resin system prepared in Example 1. Excess resin system is removed by squeezing the fiber cloth dipped with the resin system through a pressing roller to control the dip-coating amount of the resin system.

[0066] Step ii, provide a filling body of a rigid closed-cell polyurethane foam material according to the dimensions in the table above. Alternately bond the filling body to both sides of the first fiber cloth to form Figure 5 -ii honeycomb structural unit, the first fiber cloth is bent along the contour of the filling body to form a corrugated structure.

[0067] Steps iii to vii: alternately stacking a plurality of honeycomb structure units and a second fiber cloth dipped in a resin system to obtain a honeycomb structure precursor.

[0068] Step viii, curing the honeycomb structure precursor at 50°C to obtain Figure 8 The honeycomb structure shown.

[0069] As shown in the table above, the molding density of the manufactured honeycomb structure is lighter than that of balsa wood. The prepared honeycomb structure is introduced into the leading edge, trailing edge and shear rib sandwich structure of the wind turbine blade made by the vacuum resin introduction process and the ply, and the mechanical properties of the wind turbine blade sandwich structure made by each honeycomb structure are also referred to the table above. The lowest shear modulus of the obtained wind turbine blade sandwich structure in the span direction is also 211MPa, which has exceeded the shear modulus (160MPa) of balsa wood. The reason why the shear modulus is lower than that of other embodiments 2 and 4 is speculated to be that the fiber direction in the second fiber cloth is parallel or perpendicular to the thickness direction. When the fiber direction in the second fiber cloth is at an angle of 0° / 45° / -45° with the thickness direction, the shear modulus of the wind turbine blade in the span direction is higher, which is several times higher than the shear modulus (160MPa) of balsa wood.

[0070] The embodiments of the present invention are only used to illustrate the present invention and do not constitute a limitation on the scope of the claims. Other substantially equivalent alternatives that can be thought of by those skilled in the art are all within the protection scope of the present invention.

Claims

1. Honeycomb structure, Features The honeycomb wall comprises first fibers which form an angle θ with the thickness direction of the honeycomb structure, and second fibers which form an angle -θ, wherein θ is greater than 0° and less than 90°.

2. The honeycomb structure according to claim 1, Features The angle θ is 45°.

3. The honeycomb structure according to claim 1, Features It also includes a housing hole, in which a filling body made of a hard elastic closed-cell foam material is filled.

4. The honeycomb structure according to claim 3, Features The hard elastic closed-cell foam material is closed-cell polyurethane foam or closed-cell PET foam.

5. The honeycomb structure according to claim 3, Features The honeycomb wall comprises a first sub-honeycomb wall of a corrugated structure and a second sub-honeycomb wall of a planar structure. The first sub-honeycomb wall and the second sub-honeycomb wall are alternately stacked to form the honeycomb wall.

6. The honeycomb structure according to claim 5, Features At least the first sub-cell wall contains the first fibers and the second fibers.

7. The honeycomb structure according to claim 5, Features The corrugated structure of the first sub-honeycomb wall is isosceles trapezoidal grooves that are alternately opposed, and isosceles trapezoidal cells are formed between the first sub-honeycomb wall and the second sub-honeycomb wall.

8. The honeycomb structure according to claim 7, Features The base angle of the isosceles trapezoid is less than 85°, and the length of the upper base is greater than 10 mm.

9. The honeycomb structure according to claim 1, Features The honeycomb wall is formed by curing the fiber cloth impregnated with the resin system.

10. The honeycomb structure according to claim 9, Features The fiber cloth is a biaxial fiber cloth with a 45° / -45° ply or a triaxial fiber cloth with a 0° / 45° / -45° ply.

11. The honeycomb structure according to claim 1, Features The first fiber and the second fiber are respectively selected from carbon fiber, graphite fiber, glass fiber or basalt fiber.

12. Wind turbine blades, Features A honeycomb structure comprising any one of claims 1 to 11.

13. The wind turbine blade according to claim 12, Features The honeycomb structure is used for the sandwich structure of the leading edge, the trailing edge and / or the shear rib of a wind turbine blade.

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