Distribution network for composite material elements and method of manufacture

Abstract

The invention relates to a distribution network (20) for producing a composite material element, in which the distribution network (20) comprises a distribution material (21) comprising at least one epoxy-compatible group and / or a group reactive to epoxy groups.

Description

Field of the Invention

[0001] The present invention relates to a distribution net for manufacturing composite material elements and a composite material element including the distribution net. In addition, the present invention relates to a wind turbine including at least one composite material element having the distribution net. In addition, the present invention relates to a method for manufacturing a composite material element including the alternative net.

[0002] Therefore, the present invention may relate to the technical field of manufacturing composite material elements, particularly composite material elements for wind turbines. Background Art

[0003] Composite material elements are used in the manufacturing and assembly of finished products. A specific manufacturing method, namely vacuum infusion, is described below in the context of composite material elements for wind turbines.

[0004] The method for manufacturing a composite material element includes the following steps: i) placing a composite material stack on the composite part to be constructed; and ii) placing a release fabric on top of the composite material and on top of the composite material stack. Preferably, a distribution net is applied on the composite material stack. Thereby, the flow of the resin forming the composite material element in the composite material stack can be improved.

[0005] Then, a vacuum bag including the composite material stack, the release fabric, and the distribution net is formed using a vacuum foil sealed with a sealing tape. A vacuum is applied at an outlet of the vacuum foil, so that the uncured resin flows into the interior of the vacuum bag from the flow inlet.

[0006] Once the uncured resin flows into the vacuum bag, it will be distributed (uniformly) by the distribution net.

[0007] After the resin is cured, the release fabric is peeled off, thereby removing the vacuum foil and obtaining the finished composite material element.

[0008] In Figure 4 a simplified vacuum infusion configuration for manufacturing a composite material element according to the prior art is shown. In this case, after the resin for manufacturing the composite material element is cured, a removal foil 41 is required to remove the distribution net 40.

[0009] However, this manufacturing method may have disadvantages because it requires additional work to place the release fabric and the distribution net. In addition, the release fabric and the distribution net must be removed as additional waste, and these wastes are usually not reused. Therefore, the above method may be considered particularly costly and environmentally unfriendly.

[0010] Another method of manufacturing a composite component has been proposed. The method involves using a distribution mesh made of glass fibers and then integrating it into the finished composite component. In this way, there is no need to remove the mesh after manufacturing the composite component. However, when weight reduction (glass fibers may cause weight gain) and material savings are required, this method is not suitable. Summary of the Invention There is a need to manufacture composite components, especially for wind turbines, in an (cost) efficient and environmentally friendly manner.

[0012] A distribution mesh, a composite component, a wind turbine and a manufacturing method are described.

[0013] According to a first aspect of the present invention, a distribution mesh for manufacturing a composite component is described, wherein the distribution mesh comprises a distribution material which contains at least one epoxy compatibility group and / or a group reactive to epoxy.

[0014] According to a second aspect of the present invention, a composite component is described which comprises at least one distribution mesh, especially a distribution mesh according to the first aspect of the present invention.

[0015] According to a third aspect of the present invention, a wind turbine having at least one composite component, especially a composite component according to the second aspect of the present invention, is described.

[0016] According to a fourth aspect of the present invention, a method of manufacturing a composite component is provided. The method comprises: i) providing a composite material, especially dry textile layers forming a stack, ii) providing a distribution mesh containing at least one additional epoxy compatibility group and / or a group reactive to epoxy, and iii) manufacturing the composite component by embedding (encapsulating) the distribution mesh inside the composite material and by infusing the composite material and the distribution mesh with a thermosetting material (especially a resin).

[0017] According to a fifth aspect of the present invention, the use (method of use) of a distribution mesh for manufacturing a composite component is described, the distribution mesh containing at least one epoxy compatibility group and / or a group reactive to epoxy.

[0018] In the context here, the term "distribution material" (which may also be referred to as a flow medium) can be regarded as the material / part of the distribution mesh. The "distribution mesh" can be adapted to evenly distribute the resin throughout the composite material during the manufacturing process.

[0019] Such distribution materials can be in different forms in their actual applications. For example, they can be in the form of a (distribution) net in a rectangular matrix. However, this form is not mandatory, and other forms of distribution nets can also be envisaged.

[0020] In addition, the distribution materials can be made of or include different materials. Preferably, the distribution materials are thermoplastic materials so that procedures known in the prior art can be used with the said distribution net.

[0021] According to an exemplary embodiment, the present invention can be based on the idea that when a distribution net containing at least one epoxy-compatible group and / or a group reactive to epoxy is applied during the manufacturing process, composite material elements, especially those for wind turbines, can be manufactured in a (cost) efficient and environmentally friendly manner.

[0022] In the context of the present application, an "epoxy-compatible group" refers to a chemical group that does not react with epoxy resin but can be assimilated within the epoxy resin matrix.

[0023] On the other hand, a "group reactive to epoxy" refers to a group that can undergo a chemical reaction with epoxy resin to form a chemical bond.

[0024] By including at least one epoxy-compatible group and / or a group reactive to epoxy in the distribution material of the distribution net, the resin used to manufacture the composite material element can have a better bond with the distribution material of the distribution net during the curing process of the resin. Thereby, the quality of the finished product and the manufacturing method are improved.

[0025] Traditionally, the distribution net has to be removed after the resin is applied. This is because the compatibility between the net and the resin is low, resulting in poor product quality.

[0026] However, surprisingly, the inventors have found that when the distribution material contains at least one epoxy-compatible group and / or a group reactive to epoxy, excellent compatibility can be achieved. By providing such high compatibility, effectively retaining the distribution net in the resin of the composite material part is realized.

[0027] In particular, the use of epoxy-compatible groups and / or groups reactive to epoxy helps to overcome the incompatibility between the distribution material (preferably thermoplastic material) and the resin (usually thermosetting material). This difference can lead to microcracks in the finished product, thereby shortening the service life of the composite material itself.

[0028] On the contrary, by using epoxy-compatible groups and / or groups reactive to epoxy, a strong bond can be formed between the distribution material and the resin forming the composite material element, and the number of microcracks at the boundary between the distribution net and the resin can be minimized.

[0029] Without wishing to be bound by a particular theory, it is currently hypothesized that during the resin curing process, epoxy-compatible groups and / or groups reactive to epoxy play a promoting role at least in the yarn portion, thereby causing the yarn to dissolve and / or react with the resin matrix.

[0030] When compared with composite material elements known in the prior art, the resulting composite material is expected to have improved mechanical properties and a longer service life.

[0031] Furthermore, by avoiding the use of glass fibers to form the distribution network, the weight of the composite material element can be reduced in such a way.

[0032] Another advantage is the reduction of man-hours and costs, because as described above, the distribution network can be integrated or embedded into the composite material element. Therefore, the time required to manufacture the composite material element is reduced.

[0033] In addition, when the distribution network is integrated or embedded within the composite material element, material waste can be significantly reduced, making it more environmentally friendly.

[0034] Therefore, through the present invention, a distribution network that exhibits a higher affinity for the resin for forming a composite material element (especially a composite material element for a wind turbine) can be used, which benefits from epoxy compatibility and / or epoxy-reactive groups.

[0035] Exemplary Embodiments The distribution material containing at least one epoxy-compatible group and / or a group reactive to epoxy may include fibers.

[0036] The fibers can be monofilament fibers or multifilament fibers.

[0037] The fibers can be arranged in such a way that they form a network structure with variable angles and distances at the top, inside, or bottom of a non-crimp fabric (NCF). The NCF is defined as a fabric having two or more fiber layers that are stacked on top of each other and are not woven together but are held together by yarns.

[0038] The NCF can be made of glass fibers, carbon fibers, basalt fibers, natural fibers, or synthetic fibers, so NCFs including different materials are also included within the scope of the present invention.

[0039] It is also possible to combine the NCF containing at least one epoxy-compatible group and / or a group reactive to epoxy with other textiles (such as woven and non-woven textiles, such as glass yarns) to use them as distribution materials.

[0040] According to an embodiment of the present invention, the fibers forming the distribution material can be arranged in a unidirectional, bidirectional or multidirectional layer. When all the fibers are arranged along one main extension direction, the layer is unidirectional. When the fibers are arranged along two main extension directions, the layer is bidirectional. When the fibers are arranged along three or more extension directions, the layer is multidirectional.

[0041] Thus, according to an embodiment of the present invention, the distribution material can be arranged as a mesh having a rectangular or square mesh structure. Other mesh structures are also encompassed by the present invention.

[0042] According to an embodiment of the present invention, the angle between the first direction and the second direction is between 0° and 90°.

[0043] According to another embodiment of the present invention, wherein the first fiber and the second fiber define a mesh, and wherein the mesh has a mesh size between 1 and 30 mm.

[0044] According to an embodiment of the present invention, the distribution mesh further comprises a first reinforcing fiber layer structure, wherein the distribution material is arranged within or on the first reinforcing fiber layer structure. By using the first reinforcing fiber layer, the stiffness of the distribution mesh can be increased.

[0045] The first reinforcing fiber layer must be permeable to the resin so that the resin can be distributed into the composite stack.

[0046] The distribution material can be arranged on the top surface or the bottom surface of the first reinforcing fiber layer structure.

[0047] It can also be the case that the distribution material is at least partially embedded or integrated in the first reinforcing fiber layer structure.

[0048] According to an embodiment of the present invention, the first reinforcing fiber layer structure comprises or consists of at least one of the following reinforcing fibers: glass fiber, carbon fiber, basalt fiber, natural fiber or synthetic fiber.

[0049] Such fibers are commonly used in the manufacturing methods of composite elements, thus allowing the use of well-known fibers and materials in the production of composite elements according to the present invention.

[0050] As the distribution material, the first reinforcing fiber layer structure can also be unidirectional, bidirectional or multidirectional. A bidirectional reinforcing fiber layer is particularly advantageous because it can provide enhanced mechanical properties in two directions.

[0051] According to an embodiment of the present invention, the angle between the first direction of the first reinforcing fiber layer structure and the distribution material is between -60° and +60°. This angle is particularly beneficial for improving the distribution of the resin in the composite stack.

[0052] In particular, it has been found that an angle between -60° and +60° is optimal for the distribution of the resin through the distribution stack to the composite stack.

[0053] According to another embodiment of the present invention, the distribution net further comprises a second reinforcing fiber layer structure. This second reinforcing fiber layer structure further improves the structural stability of the distribution net. Additional fiber layers can be added when required for the structural properties of the composite part to be constructed.

[0054] According to one embodiment, the distribution material is arranged, in particular sandwiched between the first reinforcing fiber layer structure and the second reinforcing fiber layer structure.

[0055] In this way, the distribution material is fully supported by the reinforcing fiber layer structures on both sides.

[0056] When this is beneficial for producing the net structure in combination with the support fiber structure, the net structure can also be applied on or under the textile structure.

[0057] Therefore, the composite element has the advantages of reducing manufacturing costs and reducing labor and material requirements.

[0058] In particular, such composite elements can be elements of a wind turbine blade. Wind turbine blades need to have high standards in terms of their mechanical properties while also being lightweight. Turbine blades comprising at least one composite element according to the second aspect of the present invention are particularly advantageous as they can reduce the total labor and material costs of manufacturing the turbine blade while still improving the mechanical properties.

[0059] According to one embodiment of the present invention, it is proposed to embed the distribution net into the composite element. In this way, the distribution net can be fully integrated into the composite element, thus eliminating the need to remove the distribution net after the manufacturing process is completed.

[0060] According to another embodiment, the composite element comprises a composite material having at least one epoxy-compatible group and / or a group reactive to epoxy. In this way, an interaction (reciprocity) can occur between the distribution net comprising the epoxy-compatible group and / or the group reactive to epoxy and the resin used to make the composite material, thereby improving the performance of the composite element.

[0061] Therefore, according to the fourth aspect of the present invention, a composite material having a distribution net can be manufactured, which comprises at least one epoxy-compatible group and / or a group reactive to epoxy and has the above-mentioned advantages.

[0062] Preferably, the manufacturing method is a vacuum bag manufacturing method, in which a composite material in the form of a composite material stack and a distribution mesh are placed in a vacuum bag, and a vacuum is applied to the vacuum bag to cause the resin to flow into the vacuum bag. After the resin has flowed into the vacuum bag, the resin is cured to obtain a composite material element. In the last step, the vacuum bag is removed to obtain the finished composite material element.

[0063] The present invention is applicable not only to vacuum infusion under a vacuum bag, but also to all types of vacuum-RTM (resin transfer molding) under a high-pressure infusion process.

[0064] The above and other aspects of the present invention will be apparent from the examples of the embodiments described below and will be described with reference to the examples of the embodiments. The present invention will be described in more detail below with reference to the examples of the embodiments, but the present invention is not limited thereto. Brief Description of the Drawings Figure 1 A schematic cross-sectional view of a wind turbine according to an exemplary embodiment of the present invention is shown.

[0066] Figure 2 A distribution mesh according to an exemplary embodiment of the present invention is shown.

[0067] Figure 3 A simplified vacuum infusion configuration for manufacturing a composite material element according to an exemplary embodiment of the present invention is shown.

[0068] Figure 4 A simplified vacuum infusion configuration for manufacturing a composite material element according to the prior art is shown.

[0069] Figure 5 A simplified diagram of manufacturing a composite material element according to an exemplary embodiment of the present invention is shown.

[0070] Detailed Description of the Drawings What is shown in the figures is only schematic. It should be noted that in different figures, similar or identical elements or features are provided with the same reference numerals, or with reference numerals that differ only in the first digit from the corresponding reference numerals. In order to avoid unnecessary repetition, elements or features that have been elucidated with respect to the previously described embodiments will not be repeated in the subsequent parts of the specification.

[0071] In addition, spatial relative terms such as "front" and "rear", "upper" and "lower", "left" and "right", etc. are used to describe the relationship between the elements shown in the figures and another element. Therefore, these spatial relative terms can be applicable to usage directions different from the directions shown in the figures. Obviously, all these spatial relative terms only refer to the directions shown in the figures for the sake of description and are not necessarily restrictive, because the device according to the embodiments of the present invention can adopt directions different from those shown in the figures when in use.

[0072] Figure 1 A wind turbine 1 is shown. The wind turbine 1 includes a tower 2 which is mounted on a base not shown in the figures. A nacelle 3 is arranged at the top of the tower 2. The wind turbine 1 further includes a rotor 4 which has two, three or more blades 5 (in Figure 1 the perspective shown, only two blades 5 are visible). The rotor 4 is rotatable about a longitudinal rotation axis Y which coincides with the axial direction (also referred to as Y). Unless otherwise specified, the terms "axial", "radial" and "circumferential" hereinafter are all based on the longitudinal axis Y. The blades 5 extend radially relative to the rotation axis Y in the radial direction R. The wind turbine 1 includes a permanent magnet generator 6. According to other feasible embodiments of the present invention (not shown in the drawings), the present invention can be applied to other types of motor designs, such as induction motors, synchronous motors, etc. The rotor 4 is rotationally coupled to the permanent magnet generator 6 through a rotatable main shaft 7. The rotatable main shaft 7 extends along the rotation axis Y. The rotor 4 can also be directly rotationally coupled to the permanent magnet generator 6 (direct drive generator configuration). The permanent magnet generator 6 includes a stator 8 and a rotor 9. The rotor 9 is rotatable relative to the stator 8 about the rotation axis Y. The rotor 9 is located radially outside the stator 8 and is rotatable about the rotation axis Y. However, the present invention can also include embodiments not shown, in which the rotor 9 is located radially inside the stator 8. A circumferential air gap 10 is provided between the stator 8 and the rotor 9. Each of the three or more blades 5 includes a composite material element having an embedded distribution network 20. The manufacture of the composite material element will be described in detail below.

[0073] Figure 2 A distribution network 20 according to an exemplary embodiment of the present invention is shown. The distribution network 20 includes a distribution material 21 which, in this example, is composed of a bidirectional distribution material having first fibers 22 arranged in a first direction and second fibers 23 arranged in a second direction. Therefore, the first fibers 22 and the second fibers 23 form a network 24.

[0074] The first fibers 22 and the second fibers 23 are arranged perpendicular to each other, that is, the angle between the first direction of the first fibers 22 and the second direction of the second fibers 23 is 90°. Therefore, the network 24 has a matrix unit 25 in the shape of a rectangle (especially a square).

[0075] The distribution material 21 is sandwiched between the first reinforcing fiber layer structure 26 and the second reinforcing fiber layer structure 27. The first reinforcing fiber layer structure 26 and the second reinforcing fiber layer structure 27 provide improved mechanical stability to the distribution mesh 20.

[0076] Both the first reinforcing fiber layer structure 26 and the second reinforcing fiber layer structure 27 are unidirectional and include glass fibers in this example. However, they may also include fibers of different materials, such as carbon fibers, basalt fibers, natural fibers, or synthetic fibers.

[0077] The first reinforcing fiber layer structure 26 and the second reinforcing fiber layer structure 27 are at an angle with respect to the first fiber 22 and the second fiber 23. In particular, the angle is between -60° and +60° to optimize the flow of resin through the distribution mesh 20.

[0078] Figure 3 A simplified vacuum infusion configuration for manufacturing a composite element according to an exemplary embodiment of the present invention is shown.

[0079] In Figure 3 , the composite stack 31 is placed on the mold 32. Then the distribution mesh 20 as described above is placed on top of the composite stack 31.

[0080] A vacuum bag 33 including a vacuum foil 34 and a sealing tape 35 is used to seal the distribution mesh 20, the composite stack 31, and the mold 32.

[0081] The vacuum foil 34 has a vacuum plug 37 and a resin inlet 36, and the vacuum plug 37 is configured to be connected to a vacuum pump (not shown). When a vacuum is applied to the vacuum plug 37, resin flows into the vacuum bag 33 from the resin inlet 36. The resin is distributed evenly on the composite stack 31 through the distribution mesh 20.

[0082] When the required amount of resin has flowed in and the composite stack 31 is sufficiently impregnated with resin, the resin is cured to obtain a composite element. The distribution mesh 20 is embedded in the composite element and thus becomes part of the composite element.

[0083] Therefore, there is no need to remove the distribution mesh 20 after curing as in the case of the prior art. Thus, according to the present invention, a significant amount of time, materials, and resources are saved by manufacturing a composite element with a distribution mesh.

[0084] In Figure 5 , a simplified diagram of manufacturing a composite element according to an exemplary embodiment of the present invention is shown. The reference numerals may refer to the above-mentioned drawings.

[0085] In a first step S1, a composite material is provided, in particular dry textile layers. These dry textile layers form a textile stack 31 which will be infused with a thermosetting resin in a subsequent step.

[0086] In a second step S2, a distribution mesh 20 is provided which comprises at least one epoxy-compatible group and / or a group reactive towards epoxy.

[0087] In step S3, a composite material element is manufactured such that the distribution mesh is embedded within the composite material element.

[0088] Step S3 may include additional steps.

[0089] For example, step S31 may be provided for arranging the distribution mesh 20 at the top, bottom or in the middle of the composite material stack 31.

[0090] An additional optional step S32 is to enclose the composite material stack 31 and the distribution mesh 20 in a vacuum bag 33 with a vacuum foil 34 and a sealing tape 35.

[0091] It should also be mentioned that a VAP-film (semi-permeable film) can be used at the top of the stack 31 and the distribution mesh 20 can be used to ensure a stable infusion process.

[0092] In particular, the vacuum foil 34 may include a vacuum plug 37 and a resin inlet 36. The vacuum plug 37 is configured to be connected to a vacuum pump (not shown) to apply a vacuum to the vacuum 33.

[0093] When a vacuum is applied (step S33), the resin flows in through the resin inlet 36 and is distributed through the distribution mesh to the composite material stack 31.

[0094] In step S34, the resin is cured to form a composite material element with the embedded distribution mesh 20.

[0095] In a final step S35, the vacuum bag 33 is removed to obtain the finished composite material element.

Claims

1. A distribution network (20) for manufacturing a composite element, wherein the distribution network (20) comprises a distribution material (21), and the distribution material (21) comprises at least one epoxy-compatible group and / or a group reactive to epoxy.

2. The distribution network (20) according to claim 1, wherein the distribution material (21) is formed as fibers (22, 23).

3. The distribution network (20) according to claim 2, wherein the fibers (22, 23) are monofilament fibers or multifilament fibers.

4. The distribution network (20) according to claim 3, wherein the distribution material (21) comprises a first fiber (22) arranged in a first direction and a second fiber (23) arranged in a second direction, and wherein: the angle between the first direction and the second direction is between 0° and 90°; and / or wherein the first fiber (22) and the second fiber (23) define a network (24), and wherein the network (24) has a mesh size between 1 and 30 mm.

5. The distribution network (20) according to any one of claims 1 to 4, wherein the distribution network (20) further comprises a first reinforcing fiber layer structure (26); and wherein the distribution material (21) is arranged in or on the first reinforcing fiber layer structure (26).

6. The distribution network (20) according to claim 5, wherein the first reinforcing fiber layer structure (26) comprises or consists of at least one of the following reinforcing fibers: Glass fiber, carbon fiber, basalt fiber, natural fiber and synthetic fiber.

7. The distribution network (20) according to any one of claims 5 and 6, wherein the first reinforcing fiber layer structure (26) is configured to be unidirectional, bidirectional or multi-axial.

8. The distribution network (20) according to any one of claims 5 to 7, wherein the angle between the first direction of the first reinforcing fiber layer structure (26) and the distribution material (21) is between -60° and +60°, preferably between -30° and +30°.

9. The distribution network (20) according to any one of claims 5 to 8, wherein the distribution network (21) further comprises a second reinforcing fiber layer structure (27), and wherein the distribution material (21) is arranged, in particular sandwiched, between the first reinforcing fiber layer structure (26) and the second reinforcing fiber layer structure (27).

10. A composite element, comprising at least one distribution network (20) according to any one of claims 1 to 9.

11. The composite element according to claim 10, wherein the distribution network (20) is embedded in the composite element.

12. The composite element according to claim 10 or 11, wherein the composite element is an element of a wind turbine blade (5).

13. A wind turbine (1), comprising at least one composite element according to any one of claims 10 to 12.

14. A method for manufacturing a composite element, the method comprising: providing a composite material (31), in particular a dry textile layer forming a stack; providing a distribution network (20) comprising at least one epoxy-compatible group and / or a group reactive to epoxy; and A composite material element is manufactured by embedding the distribution network (20) inside the composite material (31) and by infusing the composite material (31) and the distribution network (20) with a thermosetting material, in particular a resin.

15. Use of a distribution network (20) for manufacturing a composite material element, said distribution network comprising at least one epoxy-compatible group and / or a group reactive towards epoxy groups.

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