Wind turbine blade comprising metal filaments and carbon fibres and a method of manufacturing thereof

Abstract

Wind turbine blade has a longitudinal direction and includes a shell structure made of a fiber-reinforced polymer material including a polymer matrix and reinforcement material comprising a plurality of carbon fiber layers embedded in the polymer matrix. At least a portion of the shell structure is formed of a laminate 6 comprising at least one metal filament layer 15, 18 comprising metal filaments and being sandwiched between two carbon fiber layers 16, 16; 17, 18 comprising carbon fibers only. The carbon fiber layers are arranged contiguously with the metal filament layer.

Claims

1. A wind turbine blade having a longitudinal direction and including a shell structure made of a fibre-reinforced polymer material including a polymer matrix and reinforcement material comprising a plurality of carbon fibre layers embedded in the polymer matrix characterised in that at least a portion of the shell structure is formed of a laminate comprising: at least one metal filament layer comprising metal filaments, a first side, and a second opposite side; and a plurality of carbon fibre layers, each carbon fibre layer comprising carbon fibres only and the carbon fibre layers being arranged on top of each other, wherein the carbon fibre layers abutting the metal filament layer are positioned on the first side of the metal filament layer and on the opposite second side of the metal filament layer.

2. The blade according to claim 1, wherein the metal filament layer is a reinforcement layer.

3. The blade according to claim 1, wherein the metal filaments are arranged substantially unidirectional.

4. The blade according to claim 1, wherein the metal filaments are arranged substantially in the longitudinal direction of the wind turbine blade.

5. The blade according to claim 1, wherein the carbon fibres constitute at least 70%, 75%, 80%, 85%, or 90% by volume of the reinforcement material of the laminate.

6. The blade according to claim 1, wherein the laminate comprises two or more mutually interspaced metal filament layers.

7. The blade according to claim 1, wherein the at least one metal filament layer comprises metal filaments only.

8. The blade according to claim 1, wherein the at least one metal filament layer comprises both metal filaments and non-metal fibres.

9. The blade according to claim 1, wherein the metal filament layer comprises at least one metal filament mat.

10. The blade according to claim 9, wherein the metal filaments of the metal filament mat are arranged in bundles.

11. The blade according to claim 10, wherein the metal filaments of the metal filament mat are arranged in bundles, comprising at least three filaments.

12. The blade according to claim 11, wherein the metal filaments of the metal filament mat are arranged in bundles, comprising at least 7, 12, 24 or 36 filaments.

13. The blade according to claim 1, wherein at least 50%, 60%, 70%, 80%, 90% or 100% of the metal filaments are arranged substantially parallel to each other.

14. The blade according to claim 1, wherein the portion of the shell structure formed by the laminate is a longitudinally extending reinforcement section comprising a plurality of non-metal fibre layers.

15. The blade according to claim 1, wherein 50%, 60%, 70%, 80%, 90% or 100% of the metal filaments of the laminate are arranged substantially in the longitudinal direction of the blade.

16. A method of manufacturing a shell structure part of a wind turbine blade, the shell structure part being made of a fibre-reinforced polymer material including a polymer matrix and a fibre-reinforcement material comprising a plurality of carbon fibre layer embedded in the polymer matrix, the method comprising the steps of: A providing a first mould part having a longitudinal direction and comprising a first forming surface with a contour defining at least a portion of an outer surface of the shell structure part; B arranging the fibre-reinforcement material in the first mould part so that at least in a longitudinal portion thereof at least one metal filament layer comprising metal filaments is sandwiched between carbon fibre layers comprising only carbon fibres, the carbon fibre layers abutting the metal filament layer; C providing a second mould part and sealing the second mould part to the first mould part so as to provide a mould cavity between the first and the second mould part; D providing resin in the mould cavity simultaneously with step B, and/or subsequently to step C; and E curing or allowing the resin to cure in order to form the shell structure part.

17. The method according to claim 16, wherein the at least one metal filament layer comprises only metal filaments, the metal filament preferably being arranged in a metal filament mat.

18. The method of claim 16, further comprising evacuating the mould cavity after step C and before step D.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in detail below with reference to the drawing(s), in which

(2) FIG. 1 shows a schematic cross section of an embodiment of a mould part with fibre material arranged in the mould part and thereby in principle also discloses a cross-sectional view of a shell half of a wind turbine blade, said shell half defining the pressure side of the blade and is to be glued to a second shell half defining the suction side of the blade along the trailing and leading edge of the blade;

(3) FIG. 2 is a cross-sectional view of a reinforcement section in the wind turbine blade;

(4) FIG. 3 shows a unidirectional metal filament mat;

(5) FIG. 4 shows a hybrid mat comprising both metal filaments and non-metal fibres;

(6) FIG. 5 is a cross-sectional view of a unidirectional metal filament mat comprising monofilaments mutually interspaced by means of weft yarns;

(7) FIG. 6 is a cross-sectional view of a unidirectional mat of monofilaments arranged in bundles, the bundles being formed of monofilaments arranged in a plane and being mutually interspaced by means of weft yarns.

(8) FIG. 7 is a cross-sectional view of a unidirectional mat formed of densely packed monofilaments arranged in bundles, each bundle comprising three monofilaments and being mutually interspaced by means of weft yarns.

(9) FIG. 8 is a cross-sectional view of a unidirectional mat comprising monofilaments densely packed in a bundle comprising seven monofilaments, the bundles being mutually interspaced by means of weft yarns.

(10) FIG. 9 shows a mat of monofilaments arranged mutually parallel and mutually interspaced and being arranged on a scrim.

DETAILED DESCRIPTION OF THE INVENTION

(11) FIG. 1 is a cross-sectional view through an embodiment of a first mould part 1 for use in VARTM process. The first mould part 1 is a rigid mould part and has an upwardly facing forming surface 2. A second mould part 3 being a so-called vacuum bag is sealed to the first mould part 1, whereby a mould cavity is formed between the first mould part 1 and the vacuum bag 3. A number of fibre layers, core parts and reinforcement sections are placed in the mould cavity, said parts being included in a finished wind turbine blade shell part, in the present example the shell half defining the pressure side of the blade.

(12) The blade shell part comprises one or more lower fibre layers 4 impregnated with resin and optionally coated with gelcoat defining the exterior surface of the shell part, and one or more upper fibre layers 5 impregnated with resin and defining the interior surface of the shell part. The upper and lower fibre layers 5, 4 may be formed of mats comprising any fibre materials, such as glass fibres, carbon fibres and/or metal filaments or a combination thereof. Between the lower and upper fibre layers 4, 5, a longitudinally extending reinforcement section, also called a main laminate 6, is arranged. The reinforcement section 6 comprises a plurality of fibre layers impregnated with resin.

(13) Arranged between the lower and upper fibre layers 4, 5 are additionally a first core part 7 and a second core part 8 as well as a trailing edge fibre-reinforcement 9 at the trailing edge 10 of the shell part and a leading edge fibre-reinforcement 11 at the leading edge 12 of the shell part.

(14) Longitudinally extending inlet channels 13also called distribution channelsare arranged on top of the upper fibre layers 5 and below the vacuum bag 3. Resin is supplied to the mould cavity through the inlet channels 13. Vacuum outlets 14 are provided at a first rim and a second rim of the first mould 1, viz. at the leading edge 12 and the trailing edge 10 of the wind turbine shell part. The mould cavity is evacuated through these vacuum outlets 14.

(15) As shown in FIG. 2, the main laminate 6 comprises the following layers: one or two centrally arranged metal filament layers 15 sandwiched between two first intermediate carbon fibre layers 16 only comprising carbon fibres and being contiguous with the respective centrally arranged metal filament layer 15; and two second intermediate carbon fibre layers 17 only comprising carbon fibres and contiguous with the respective first intermediate carbon fibre layer 16.

(16) The main laminate 6 further comprises first intermediate metal filament layers 18 being contiguous with the respective second intermediate carbon fibre layer 17, and outer carbon fibre layers 19 being contiguous with the respective first intermediate metal filament layer 18.

(17) As can be seen, the main laminate 6 may comprise two or more metal filament layers 15, 18 for flow enhancement during the infusion process. However, it should be noted that the figure is for illustrative purposes only and is drawn out of scale, since the metal filament layers typically will be sandwiched between a plurality of carbon fibre layers.

(18) As an example, the main laminate may be constructed with carbon fibre layer sections with e.g. twenty carbon fibre layers and intermediate metal filament layers for the flow enhancement, i.e. as an example twenty carbon fibre layers, one metal filament layer, twenty carbon fibre layers, one metal filament layer and finally twenty carbon fibre layers.

(19) The wind turbine shell half is manufactured as follows:

(20) The lower fibre layers 4 are arranged on the upwardly facing forming surface 2 of the first rigid mould part 1. Then the layers of the main laminate 6, the core parts 7 and 8 and the trailing edge fibre-reinforcement 10 and the leading edge fibre-reinforcement 11 are arranged on top of the lower fibre layers 4. The upper fibre layers 5 are then arranged and on top thereof the longitudinally extending inlet channels 13. Finally, the vacuum outlets 14 arranged and the vacuum bag 3 is sealed to the first rigid mould part 1 to form the mould cavity. The mould cavity is then evacuated through vacuum outlets 14 and resin is supplied to the mould cavity through inlet channels 13.

(21) Resin is subsequently supplied to the inlet channels 13 so as to provide a resin flow front gradually moving towards the vacuum outlets 14 in the transverse direction of the mould. The central metal filament layers 15 sandwiched between the first intermediate carbon fibre layers 16, 16 and the first intermediate metal filament layers 18 sandwiched between the outer carbon fibre layer 19 and the second intermediate carbon fibre layer 17 function as distribution layers. As a result, the metal filament layers allow for distribution of resin to the adjacent carbon fibre layers so that these layers are impregnated with resin without dry spots being formed. In addition, the metal filaments function as a reinforcement layer in the blade shell increasing the stiffness of the blade. The metal filaments may advantageously be arranged substantially unidirectional in the longitudinal direction of the blade shell.

(22) After resin impregnation of all of the fibre layers, the resin is allowed to cure, whereafter the moulded shell half is removed from the mould.

(23) The metal filaments of the metal filament layers are preferably steel fibres and preferably arranged in metal filament mats. The metal filament mats may be unidirectional mats comprising primarily filaments extending in the longitudinal direction or multidirectional mats. Further they may be mats comprising only metal filaments or be so-called hybrid mats comprising both metal filaments and non-metal fibres such as carbon fibres.

(24) FIG. 3 shows a portion of a metal filament mat being a unidirectional mat comprising a number of mutually parallel metal filaments. The metal filaments 20 are mutually interspaced by means of weft yarns 21, 22 extending transversely of the longitudinal direction of the metal filaments 20. The metal filaments 20 shown in FIG. 3 may be monofilaments or bundles of filaments as explained below.

(25) FIG. 4 shows a portion of hybrid mat 23 comprising steel filaments 24 and non-metal fibres 25, such as carbon fibres which woven together. In FIG. 4 the non-metal fibres 25 may be multi-strand carbon fibres, where the individual fibres have a diameter being substantially smaller than that of the steel filaments. The steel filaments 24 may be monofilaments or bundles of filaments, as explained below.

(26) Both the unidirectional mat 26 shown in FIG. 3 and the hybrid mat 23 shown in FIG. 4 may be used as metal filament mats in the main laminate 6 shown in FIGS. 1 and 2.

(27) FIG. 5 is a sectional view of a part of a metal filament mat 41 comprising mutually parallel and mutually interspaced monofilaments 30 of metal, the monofilament being interspaced by means of the weft yarns 31, 32.

(28) FIG. 6 is a sectional view of part of a metal filament mat 26 comprising bundles of metal filaments 27 and wherein the bundles comprise five metal filaments 27 arranged in a common plane, and wherein the bundles of metal filaments 27 are separated by means of crossing weft yarns 28, 29.

(29) FIG. 7 is a sectional view of a portion of a metal filament mat 42 comprising bundles of three metal filaments 33, the bundles being interspaced by means of weft yarns 34, 35.

(30) FIG. 8 is a sectional view of a portion of a metal filament mat 43 comprising bundles of seven metal filaments 36 being closely packed and wherein the bundles of metal filaments 36 are mutually interspaced by means of weft yarns 37, 38.

(31) The filaments of the bundles may be twisted in the longitudinal direction with a relatively high pitch length. However, it is preferred that that the individual filaments are non-twisted as this yields a better compression strength and also a better wetting of the carbon fibres.

(32) FIG. 9 is a sectional view of a portion of a metal filament mat 44 comprising mutually parallel and interspaced monofilaments 39 arranged in a common plane. The monofilaments 39 are arranged on a backing sheet or scrim 40 having an open structure, such as a weakened or knitted structure allowing easy passage of resin through said scrim.

(33) The invention has been described with reference to advantageous embodiments. However, the scope of the invention is not limited to the illustrated embodiment, and alterations and modifications may be carried out without deviating from the scope of the invention.

LIST OF REFERENCE NUMERALS

(34) 1 First rigid mould part 2 Upwardly facing forming surface 3 Second mould part (vacuum bag) 4 Lower fibre layers 5 Upper fibre layers 6 Reinforcement section (main laminate) 7 First core part 8 Second core part 9 Trailing edge fibre-reinforcement 10 Trailing edge of the shell part 11 Leading edge fibre-reinforcement 12 Leading edge of the shell part 13 Inlet channels 14 Vacuum outlets 15 Centrally arranged metal filament layer 16 First intermediate carbon fibre layer 17 Second intermediate carbon fibre layer 18 First Intermediate metal filament layer 19 Outer carbon fibre layers 20 Metal filaments 21, 22 Weft yarns 23 Hybrid mat 24 Steel filaments 25 Non-metal fibres 26 Metal filament mat 27 Metal filaments 28, 29 Weft yarns 30 Monofilaments 31, 32 Weft yarns 33 Metal filaments 34, 35 Weft yarns 36 Metal filaments 37, 38 Weft yarns 39 Monofilaments 40 Scrim 41 Metal filament mat 42 Metal filament mat 43 Metal filament mat 44 Metal filament mat