Fiber-reinforced composite, a component and a method

Abstract

A fiber reinforced composite, a component for a wind turbine and a method for manufacturing a component for a wind turbine are provided. The fiber reinforced composite includes a plurality of first fibers, the first fibers being arranged in a unidirectional or biax-configuration, a plurality of second fibers, the second fibers being arranged perpendicularly with respect to a lengthwise direction of the first fibers, and a resin impregnating the first and second fibers, wherein a E-modulus of the resin equals an E-modulus of the second fibers. Since the E-modulus of the resin and the E-modulus of the second fibers are equal, an early initiation of fatigue cracks is avoided.

Claims

1. A fiber reinforced composite for manufacturing a component for a wind turbine, comprising a plurality of first fibers, the fibers being arranged in an unidirectional or biax-configuration, a plurality of second fibers, the second fibers being arranged perpendicularly with respect to a lengthwise direction of the first fibers, and a resin impregnating the first and second fibers such that the first and second fibers are embedded in the resin, wherein a Young's modulus of the resin equals a Young's modulus of the second fibers, wherein the Young's modulus of the resin and the second fibers is smaller than the Young's modulus of the first fibers.

2. The fiber reinforced composite of claim 1, wherein the Young's modulus of the second fibers and the resin is in the range of 1 to 6 GPa and wherein a Young's modulus of the first fibers is at least 70 GPa.

3. The fiber reinforced composite of claim 1, wherein the plurality of first fibers are arranged in the biax-configuration such that an angle between the plurality of first fibers and the lengthwise direction is 45 degrees.

4. The fiber reinforced composite of claim 1, wherein the plurality of second fibers are arranged perpendicularly such that an angle between the plurality of second fibers and the lengthwise direction is in a range of 90±20 degrees.

5. A method for manufacturing a component for a wind turbine using the fiber reinforced composite of claim 1, comprising a) providing a fiber material comprising the plurality of first fibers and the plurality of second fibers, b) laying the fiber material onto a mold surface, and c) curing the resin impregnating the first and second fibers to form the component.

6. A fiber reinforced composite for manufacturing a component for a wind turbine, comprising a plurality of first fibers, the fibers being arranged in an unidirectional or biax-configuration, a plurality of second fibers, the second fibers being arranged perpendicularly with respect to a lengthwise direction of the first fibers, and a resin impregnating the first and second fibers such that the first and second fibers are embedded in the resin, wherein a Young's modulus of the resin equals a Young's modulus of the second fibers, wherein the second fibers are made of a thermoplastic material and/or a resin.

7. The fiber reinforced composite of claim 6, wherein the second fibers are made of epoxy resin, PET, polyester, acrylic, polycarbonate, polyimide, ABS and/or polypropylene.

8. A fiber reinforced composite for manufacturing a component for a wind turbine, comprising a plurality of first fibers, the fibers being arranged in an unidirectional or biax-configuration, a plurality of second fibers, the second fibers being arranged perpendicularly with respect to a lengthwise direction of the first fibers, and a resin impregnating the first and second fibers such that the first and second fibers are embedded in the resin, wherein a Young's modulus of the resin equals a Young's modulus of the second fibers, wherein the second fibers each comprise multiple filaments.

9. The fiber reinforced composite of claim 8, wherein each filament has a diameter ranging from 2 to 20 μm.

10. A fiber reinforced composite for manufacturing a component for a wind turbine, comprising a plurality of first fibers, the fibers being arranged in an unidirectional or biax-configuration, a plurality of second fibers, the second fibers being arranged perpendicularly with respect to a lengthwise direction of the first fibers, and a resin impregnating the first and second fibers such that the first and second fibers are embedded in the resin, wherein a Young's modulus of the resin equals a Young's modulus of the second fibers, wherein the second fibers are each formed as a single fiber.

11. The fiber reinforced composite of claim 10, wherein the diameter of a respective single fiber ranges from 50 to 500 μm.

12. A fiber reinforced composite for manufacturing a component for a wind turbine, comprising a plurality of first fibers, the fibers being arranged in an unidirectional or biax-configuration, a plurality of second fibers, the second fibers being arranged perpendicularly with respect to a lengthwise direction of the first fibers, and a resin impregnating the first and second fibers such that the first and second fibers are embedded in the resin, wherein a Young's modulus of the resin equals a Young's modulus of the second fibers, wherein the second fibers are attached to the first fibers by means of a stitching yarn.

13. A fiber reinforced composite for manufacturing a component for a wind turbine, comprising a plurality of first fibers, the fibers being arranged in an unidirectional or biax-configuration, a plurality of second fibers, the second fibers being arranged perpendicularly with respect to a lengthwise direction of the first fibers, and a resin impregnating the first and second fibers such that the first and second fibers are embedded in the resin, wherein a Young's modulus of the resin equals a Young's modulus of the second fibers, wherein the second fibers are treated with a coupling agent to improve a mechanical connection at an interface between the second fibers and the resin.

14. A fiber reinforced composite for manufacturing a component for a wind turbine, comprising a plurality of first fibers, the fibers being arranged in an unidirectional or biax-configuration, a plurality of second fibers, the second fibers being arranged perpendicularly with respect to a lengthwise direction of the first fibers, and a resin impregnating the first and second fibers such that the first and second fibers are embedded in the resin, wherein a Young's modulus of the resin equals a Young's modulus of the second fibers, wherein the resin is cured such that the fiber reinforced composite takes the form of the component for the wind turbine.

15. The fiber reinforced composite of claim 14, wherein the component comprises a rotor blade.

16. A fiber reinforced composite for manufacturing a component for a wind turbine, comprising a plurality of first fibers, the fibers being arranged in an unidirectional or biax-configuration, a plurality of second fibers, the second fibers being arranged with an angle between the plurality of second fibers and a lengthwise direction of the first fibers, said angle in a range between 45 and 90 degrees, a resin impregnating the first and second fibers such that the first and second fibers are embedded in the resin, wherein a Young's modulus of the resin is substantially equal to a Young's modulus of the second fibers; and a stitching yarn, wherein the second fibers are attached to the first fibers with the stitching yarn.

17. The fiber reinforced composite of claim 16, wherein the Young's modulus of the second fibers is greater than the Young's modulus of the resin and wherein the Young's modulus of the second fibers is up to 5 times the Young's modulus of the resin.

18. The fiber reinforced composite of claim 16, wherein the plurality of second fibers are arranged in a zigzag configuration such that the angle between the plurality of second fibers and the lengthwise direction is 45 degrees.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further objects, features and advantages of the present invention become apparent from the subsequent description and depending claims, taken in conjunction with the accompanying drawings, in which

(2) FIG. 1 is a perspective view of a wind turbine according to an embodiment;

(3) FIG. 2A shows a top view of a fiber-reinforced composite according to an embodiment;

(4) FIG. 2B shows an enlarged view from FIG. 2A according to an embodiment;

(5) FIG. 2C shows an enlarged view from FIG. 2A according to a further embodiment;

(6) FIG. 3 shows a top view of a fiber-reinforced composite according to a further embodiment;

(7) FIG. 4 shows a top view of a fiber-reinforced composite according to a further embodiment;

(8) FIG. 5 shows a section view from a VARTM-process according to a method for manufacturing the rotor blade of FIG. 1; and

(9) FIG. 6 shows a flowchart in accordance with an embodiment of a method for manufacturing a component for a wind turbine.

(10) In the Figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated.

DETAILED DESCRIPTION OF INVENTION

(11) FIG. 1 shows a wind turbine 1 according to an embodiment.

(12) The wind turbine 1 comprises a rotor 2, connected to a generator (not shown) arranged inside a nacelle 3. The nacelle 3 is arranged at the upper end of a tower 4 of the wind turbine 1.

(13) The rotor 2 comprises three blades 5. Rotors 2 of this kind may have diameters ranging from, for example, 30 to 160 meters. The blades 5 are subjected to high wind loads. At the same time, the blades 5 need to be lightweight. For these reasons, the blades 5 in modern wind turbines 1 are manufactured from fiber-reinforced composite material. Therein, glass fibers are generally preferred over carbon fibers for cost reasons. In addition, the blades 5 may each comprise one or more core members made of a lightweight material to reduce the weight of the blades 5.

(14) FIG. 2A shows in a top view a fiber-reinforced composite 6 according to an embodiment.

(15) The fiber-reinforced composite 6 comprises a plurality of first fibers 7. The first fibers 7 are configured as rovings, but may also take a different form. The first fibers 7 are arranged in a unidirectional configuration, i.e. all fibers 7 extend in the same direction 8 hereinafter referred to as the “lengthwise direction” of the first fibers 7.

(16) Further, the fiber reinforced composite 6 comprises second fibers 9. The second fibers 9 may be configured as fibers, yarns, rovings, beads of adhesive, strings or bands of material.

(17) The second fibers may be made of (partially or fully) epoxy resin, PETP, PET, polyester, acrylic, polycarbonate, polyimide, ABS, polypropylene or combinations thereof. Epoxy resin, PETP, PET, polyester may be preferred.

(18) These materials used for making the second fibers are also given in the table below including corresponding E-modulus values (also called Young's modulus). However, the E-modulus values given are not to be understood in a limiting sense. Rather, these values correspond to preferred values.

(19) TABLE-US-00001 TABLE Material Youngs modulus/E-modulus [GPa] Epoxy resin 3 PET, Polyester   2-2.7 Acrylic 3.2 Poly Carbonate 2.6 Poly imid 2.5 ABS 2.3 Poly propylene 1.5-2  

(20) Now returning to FIG. 2A, the first and second fibers 7, 9 are embedded in a cured resin 10. FIG. 2A only shows a portion of the resin 10 for reasons of clarity. The resin 10 may comprise an epoxy resin, for example. As indicated in the table above, the epoxy resin has an E-modulus of 3 and is thus very similar to the E-modulus of the material of the second fibers 9.

(21) Now considering the E-modulus of the first fibers, which may be made of glass fibers and/or carbon fibers having an E-modulus of 75 GPa and 240 GPa, respectively, the E-moduli of the resin 10 and the second fibers 9 are considered equal.

(22) An individual fiber 9 as shown in FIG. 2A may be configured has illustrated in FIG. 2B or 2C, for example.

(23) According to the embodiment of FIG. 2B, the fiber 9 comprises multiple filaments 11. Each filament 11 may have a diameter D ranging from 2 to 20 μm, for example.

(24) In the embodiment according to FIG. 2C, the fiber 9 is configured as a single fiber. The fiber 9 has a diameter D ranging from 50 to 500 μm, for example.

(25) Now returning to FIG. 2A, it is shown that the second fibers 9 may be attached to the first fibers 7 by means of a stitching yarn 12.

(26) Further, FIG. 2A illustrates that the second fibers 9 may extend at an angle α of 90° with respect to the lengthwise direction 8.

(27) FIG. 3 shows a top view of a composite 6 according to a further embodiment.

(28) The embodiment of FIG. 3 differs from the embodiment of FIG. 2A in that the second fibers 9 are arranged at an angle α of 45° with respect to the lengthwise direction 8. The second fibers 9 are thus arranged in a zigzag configuration. In other embodiments, the angle may range between 45° and 90°, or between 70° and 90°.

(29) FIG. 4 shows a top view of a composite 6 according to a further embodiment.

(30) The embodiment of FIG. 4 differs from the embodiment of FIG. 2A in that the first fibers 7 are arranged in a biax configuration. In other words, the first fibers 7 are arranged at angles of +/−45° with respect to the lengthwise direction 8.

(31) FIG. 5 illustrates a section view from a VARTM-process in accordance of an embodiment of the present invention. Reference is also made to FIG. 6 illustrating a low diagram of a method for manufacturing a rotor blade 5 as shown in FIG. 1, for example.

(32) In step S1 an (optional) vacuum distribution layer 13 is arranged on a mold surface 14 of a mold 15.

(33) In a step S2, a fiber material 16 is provided. The fiber material 16 comprises first and second fibers 7, 9 as shown in FIGS. 2A to 4 above. The fibers 7, 9 may at this point be fastened together by a stitching yarn 12 to improve handling of the fibers 7, 9.

(34) In a step S3, the fiber material 16 is arranged on top of the vacuum distribution layer 13, or directly on the mold surface 14 when no vacuum distribution layer 13 is provided.

(35) In a step S4, the fiber material 16 is covered with a vacuum bag 17. Then vacuum is applied to the space between the vacuum bag 17 and the mold surface 14 by a vacuum pump 18.

(36) In a further embodiment, the vacuum distribution layer 13 is arranged on top of the fiber material 16. Then, the vacuum bag 17 is arranged on top of the vacuum distribution layer 13.

(37) In a step S5, a resin, in particular an epoxy resin, is injected into said space. The second fibers 9 may be treated with a coupling agent (not shown) before injecting the resin 10 in step S5.

(38) In a step S6 external heat is applied to the mold 15 curing the epoxy resin.

(39) After removing the vacuum bag 17 and/or opening the mold 18 (in the case of closed mold), the finished blade 5 may be removed from the mold in a step S7.

(40) Of course, the steps S1 to S7 may be modified to include the positioning of a mold core (not shown) and/or a web (not shown) in the mold 15 to provide a blade of 5 reinforced by a web or balsa wood and/or foam core, for example.

(41) Although the present invention has been described in accordance with preferred embodiments, it is obvious for a person skilled in the art that modifications are possible in all embodiments.