EP3679244A1

EP3679244A1 - A shear web element for a wind turbine blade

Info

Publication number: EP3679244A1
Application number: EP18766217.6A
Authority: EP
Inventors: Lars Tilsted Lilleheden
Original assignee: Fiberline Composites AS
Current assignee: Fiberline Composites AS
Priority date: 2017-09-07
Filing date: 2018-09-06
Publication date: 2020-07-15
Also published as: WO2019048535A1

Abstract

A kit-of-parts for manufacturing a shear web (14) for a wind turbine blade (12). The kit comprises a base (16) being rolled up into a first roll, and a connecting element, being rolled up into a second roll. The base (16) and the connecting element constitutes a web-joint element (10). The base (16) defines a flange of said web-joint element (10), and comprises a bottom surface (20) for adhering to an internal surface of the wind turbine blade (12), and a base joint part (24) on the opposite side of the bottom surface (20). The connecting element (18) defines a web (14) of the web-joint element (10), and comprises a bearing end (28), having a connecting joint part (25) for cooperating with the base joint part (24) thereby providing a joint. A web-joint element (10) and a method for manufacturing a shear web for a wind turbine blade are also described.

Description

A shear web element for a wind turbine blade

DESCRIPTION The present invention relates to a shear web for a wind turbine blade, and to a method of manufacturing a shear web for a wind turbine blade.

Typically, the structural rigidity of a wind turbine blade is enhanced with panels placed on parts or areas of the interior surface of the wind turbine blade. Additionally, spar caps running span wise along an interior surface may also be used to enhance the structural rigidity.

In this context span wise refers to the direction from the hub end to the tip end of the wind turbine blade. The hub end is fixed to the rotor hub of the wind turbine.

Furthermore, a number of shear webs may be placed in the interior space of the blade between the two half-parts of the blade.

An example of a method of enhancing the structural rigidity of a wind turbine blade is disclosed in WO 17/016566, which disclosure is incorporated in the present application by reference. As can be seen on fig. 3a of WO 17/016566 two shear webs are placed in the interior space of the wind turbine blade. The shear webs provide additional structural rigidity compared to a wind turbine blade without shear webs. Modern wind turbines with a MW output, such as more than 5 MW, have blades, which approach a span of up to 100 m, and it is contemplated that the blades will have an even greater span in the future, possibly with the aid of the present invention.

Thus, a wind turbine blade is a relative long structure, which makes the logistics involved in transporting parts for the wind turbine relatively complicated. Furthermore, the profile of the blade varies along the span of the blade, i.e. the circumference of the blade becomes smaller towards a tip end of the blade, and the shape of the profile also varies along the span. It is an object of the present invention to provide a shear web, which may extend uninterrupted over a major part of the span of the blade, i.e. without having to assemble the shear web from a number of short shear webs, which are placed in extension of each, which means that the structure has partitions or separations.

With the present invention it is possible to enhance the structural rigidity of the wind turbine blade such that the blade becomes more stable and can operate under higher stress, i.e. such that the blade can operate with a higher load or a higher pressure difference between a suction and pressure side of the blade or simply rotate at a higher frequency. In particular, it is an object of the present invention to make the manufacturing of the shear web as well as the wind turbine blade more effective.

The above object and advantages together with numerous other objects and advantages, which will be evident from the description of the present invention, are ac- cording to a first aspect of the present invention obtained by:

A kit-of-parts for manufacturing a shear web for a wind turbine blade, said kit-of-parts comprising

a base being rolled up into a first roll, and a connecting element, being rolled up into a second roll,

said base, and said connecting element constituting a web-joint element, said base defining a flange of said web-joint element, and comprising a bottom surface for adhering to an internal surface of said wind turbine blade, and

a base joint part on the opposite side of said bottom surface, said connecting element defining a web of said web-joint element, and comprising a bearing end, having a connecting joint part for cooperating with said base joint part for providing a joint.

A joint may comprise a bearing for providing free movement of a moving part.

Said kit-of-parts may further comprise a pair of wind turbine blade shells for constituting a wind turbine blade when the pair of shells being put together. The connecting element may be manufactured in a pultrusion process, and be made of a fiber reinforced polymer such as a glass fiber polymer. Alternatively, the connecting element may be extruded in a thermos-plastic or be made of wood or foam. According to a second aspect of the present invention, the above objects and advantages are obtained by:

A method of manufacturing a shear web for a wind turbine blade, said method comprising:

providing a first web joint element encompassing

a first base with a first base joint part, and

a first connecting element with a first connecting joint part for cooperating with said first base joint part for providing a first joint,

said first base and said first connecting element being connected by means of said first joint,

providing a second web joint element encompassing

a second base with a second base joint part, and

a second connecting element with a second connecting joint part for cooperating with said second base joint part for providing a second joint,

said second base and said second connecting element being connected by means of said second joint,

providing a mold with a mold surface for shaping said shear web, said mold having a first edge area for imparting a first angle to said first joint, and a second edge area for imparting a second angle to said second joint, said second edge area being opposite said first edge area,

providing in said mold an assembly comprising

- a first fabric on said mold surface,

- said first web joint element placed on said first fabric at said first edge area, and said second web joint element placed on said first fabric at said second edge area such that said first joint being pivoted to said first angle, and said second joint being pivoted to said second angle with said first connector facing said second connector,

- a web placed on said first fabric between said first web joint element and said second web joint element,

- a second fabric placed on said first web joint element, said web, and said second web joint element such that said first web joint element, said web, and said second web joint element being sandwiched between said first fabric and said second fabric, providing a curable infusion material in fluid form, and infusing said curable infusion material in said assembly, and curing said curable infusion material.

The first fabric and/or the second fabric may be a pre-impregnated composite fiber, where a thermoset polymer matrix material, such as epoxy, is already present.

When the curable infusion material has cured, the shear web has been assembled into its final form. It may then be removed from the mold, and placed in a blade. Any excess infusion material may be removed from the shear web.

The mold is shaped according to the dimensions of a specific blade, which the shear web is to be installed in. The shear web is to be a continuous element extending over a major part of the span of the blade. The shear web may have a length of more than 50 m. The web may be a block of foam or porous material. The web may also have wood as a sandwich structure.

An edge area means an area that extends on both of the surfaces, which meet at the edge, i.e. an upper surface and a side surface meet at the edge. On the upper surface, the edge area extends from the edge and a distance over the upper surface towards the opposite edge - the distance corresponding to the height of the connecting element.

On the side surface, the edge area extends from the edge and a distance over the side surface - the distance corresponding to half the width of the base.

A web joint element provides for a standard part, which can be used with a multitude of different wind turbine blades in order to manufacture a shear web in an efficient manner. This alleviates a need for the production of customized parts.

Each base as well as each connecting element may be made from a composite material such as a fiber reinforced polymer, which is a composite material made of a polymer matrix reinforced with fibers. The fibers may be glass, carbon, aramid, basalt or wood. The polymer may be an epoxy, vinylester, or polyester thermosetting plastic. Such a polymer may also be used as the curable infusion material. Each connecting element may alternatively be made from a foam or porous material.

The first fabric and/or the second fabric may be a sheet of woven fibers such as glass fibers.

A major part of the span of the wind turbine blade may be 90 % of the length from a tip end of the blade to the hub end of the blade, alternatively 80 % or lower such as 70 %, 60 % or 50 %. A base and/or a connecting element may be pultruded in an pultrusion process. Alternatively, it may be manufactured in an extrusion process where a die provides the negative space of a spar cap, and the material used is pressed through the die. It may also be molded in a casting process or an infusion process. A single base may be produced and afterwards divided into a plurality of bases with the needed lengths for a particular blade. Such a single base has a length greater than a wind turbine blade, i.e. such as a length of more than 25 m, such as more than 30 m, 45 m, 60 m, 75 m, or 90 m. The length of a base is measured from a tip end of the base to a (opposite placed) hub end of the base.

After a base has been produced or during production it may be rolled up for transport. A single connecting element may be produced and afterwards divided into a plurality of connecting elements with the needed lengths for a particular blade. Such a single connecting element has a length greater than a wind turbine blade, i.e. such as a length of more than 25 m, such as more than 30 m, 45 m, 60 m, 75 m, or 90 m. After a connecting element has been produced or during production it may be rolled up for transport, or divided into a plurality of connecting elements having a length suitable for transport such as 4 to 6 meters. Said length being measured from a tip end of the connecting element to a (opposite placed) hub end of the connecting element. According to a third aspect of the present invention, the above objects and advantages are obtained by: A shear web for a wind turbine blade, said shear web comprising:

a first web joint element encompassing

a first base with a first base joint part, and

a second web joint element encompassing

a second base with a second base joint part, and

said first connecting element facing said second connecting element,

said shear web further comprising

a web between said first connecting element and said second connecting element,

said first web joint element, said second web joint element and said web being sandwiched between a first fiber reinforced polymer and a second fiber reinforced polymer,

said first fabric, said second fabric, said first web joint element, said second web joint element, and said web being fixed to each other by means of an infusion material. According to a fourth aspect of the present invention, the above objects and advantages are obtained by:

A web joint element for joining a shear web of a wind turbine blade to an internal surface of said wind turbine blade, said web joint element comprising

a base, and

a connecting element,

said base constituting a flange with respect to said connecting element, and encompassing a bottom surface for adhering to said internal surface of said wind turbine blade, and

a base joint part on the opposite side of said bottom surface, said connecting element constituting a web with respect to said spar cap, and encompassing a bearing end, said bearing end having a connecting joint part for cooperating with said base joint part for providing a joint,

said web joint element comprising an adhesive material between said spar joint part and said connecting joint part.

The invention will now be explained in more detail below by means of examples of embodiments with reference to the very schematic drawing, in which Fig. 1A shows an exploded view of a web joint element.

Fig. 1 B shows a rolled up connecting element and a rolled up base.

Fig. 2 shows a web joint element.

Fig. 3A-3E shows an assembly of a shear web in a mold. Fig. 3F shows a shear web. Fig. 4 shows a wind turbine blade.

Fig. 5A shows the cross section AA' of the blade in fig. 4. Fig. 5B shows the cross section BB' of the blade in fig. 4.

Fig. 5C shows the cross section CC of the blade in fig. 4. Fig. 6 shows a blade cross section of a wind turbine blade. The present invention will now be described more fully hereinafter with reference to the accompanying drawing, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout, thus, like elements will not be described in detail with respect to the description of each figure.

Fig. 1A shows an exploded view of a web joint element 10 for manufacturing a shear web 1 1 for a wind turbine blade 12.

The web joint element comprises a base 16 and a connecting element 18.

The base has a bottom surface 20 for placing on an interior surface 22 of the wind tur- bine blade. A typical bonding is used as joining method.

The base is to function as a flange with respect to the connecting element, which is to be placed with an angle φ of about 90°±30° with respect to the flange, and thereby establish a T-profile, i.e. a profile having a cross section in the shape of the letter T. The angle may alternatively be ranging in the range 90°±20° or 90°±10°.

Opposite the bottom surface, the base has a base joint part 24 with a bearing having a U-shaped cross section. The base joint part defines a cavity for accommodating the connecting element.

In the present context, any mentioning of a cross section of an element will refer to a cross section in a plane orthogonal to the longitudinal extent of the element.

The connecting element have a planar geometry (generally meaning that a width is small compared to both height and length). It has a cross section with a shape in the form of a wedge.

The connecting element comprises a tapered end 26 and a bearing end 28 opposite the tapered end. The width of the connecting element at the bearing end is greater than the width of the connecting element at the tapered end. The height of the connecting element measured from the tapered end to the bearing end is smaller than the length of the connecting element.

The connecting element has a first side wall 30 and an opposite second side wall 32 between the bearing end and the tapered end - the two side walls coming closer together approaching the tapered end. The bearing end is rounded (as seen in its cross section), and has a shape matching the bearing of the base thereby constituting a connecting joint part 25 for cooperating with the base joint part and providing a joint. The joint has a rotation axis parallel with the lengthwise direction of the web joint.

The U-shaped bearing has an opening (defined by the space between the ends of the two legs of the U), and surrounds the bearing end for 180°. The U-shaped bearing may alternatively be C-shaped and thereby surround the bearing end for more than 180°.

Both the spar cap and the connecting element has a constant cross section along the length of the two. Thus, a cylindrical joint is established in which the connecting element may rotate or pivot around the joint (rotation axis).

The base joint part has a protrusion 21 (in fig. 1 A three protrusions can be seen). The protrusion provides a gap or space between the base joint part and the connecting joint part, i.e. the connecting joint part has an even surface so that the connecting joint part contacts the protrusion when the joint parts are joined

It is contemplated that the connecting joint part may have a protrusion instead of the base joint part.

Fig. 1 B shows a connecting element and a base, both of which have been rolled into rolls, i.e. the base is rolled up lengthwise with the bottom surface facing downwards and by folding a tip end 64 360°, and continuing turning until the entire base has been rolled up. The connecting element is rolled flat up such that the side wall becomes par- allel in respective turns of the roll.

The tip end of the base is intended to be towards the tip end 40 of the blade 12, and a hub end 66 of the base is intended to be towards the hub end 38 of the blade.

A tip end 60 of the connecting element is intended to be towards the tip end 40 of the blade 12, and a hub end 62 of the connecting element is intended to be towards the hub end 38 of the blade. Both the base and the connecting element may be manufactured in a molded process, an extrusion process or a pultrusion process. They may be made as a fiber reinforced polymer material. The base and the connecting element may be produced with lengths of more than 50 m, such as more than 75 m or 100 m, and cut into lengths matching a specific blade.

Fig. 2 shows a web joint element similar to the one shown in fig. 1 A, but with the joint parts interchanged, i.e. in this case the bearing end of the connecting element has a connecting joint part in the form of a inverse U-shaped bearing defining a cavity for accommodating the base, and the base has a base joint part which protrudes from the spar cap and is rounded for matching the U-shaped bearing. The base and the connecting element constitute a kit-of-parts, meaning that they are standard components manufactured without prior knowledge of a specific blade. The joint constituted by the base joint part and the connecting joint part makes the web joint element flexible in that the joint can be pivoted to a specific angle for matching a specific blade. The joint angle is to be understood as the angle φ between the base and the connecting element.

Figs. 3A to 3E show the manufacturing of the shear web using the kit-of-parts, i.e. the web-joint element. Specifically, two web-joint elements are used to manufacture the shear web. Fig. 3F shows a manufactured shear web, which is to be placed in a blade.

The shear web is manufactured using an assembly comprising the two web-joint elements 53,55, two sheets of fabric 68,70, and a web 14 constituted by a block of foam material. The parts are to be fixed together and reinforced with an epoxy material. In fig. 3A a mold 78 is provided. Fig. 3A shows the cross section of the mold. The purpose of the mold is to aid in assembling the assembly and make the shear web match a specific blade.

The mold is a block defining a positive mold that the assembly aligns itself after, which will be explained in more detail in the following. The mold has an upper surface between a first edge 74, and a second edge 76, (which is opposite the first edge). The upper surface is horizontal.

Adjoining the first edge is a first side surface, and adjoining the second edge is a sec- ond side surface.

The first side surface has a first inclination, and the second side surface has a second inclination. The dimension and shape of the mold is determined by the specific blade, which the shear web is to be placed in.

The mold has a hub end defining the shape of the shear web, which is to be closest to the hub end of the blade. The mold has a tip end defining the shape of the shear web which is to be closest to the tip end of the blade.

The length of the mold is the distance between the hub end and the tip end of the mold. A mold for a shear web for a blade with a span of 100 m will have a length of 90 m if the shear web is to extend over 90 % of the blade.

The width of the mold corresponds to the height of the shear web. The width of the mold is defined as the distance between the first edge and the second edge. The width varies with the length of the mold. The mold is wider at the hub end than at the tip end. The mold has been made so that the width as a function of the length matches the internal height of the blade as at varies along the span of the blade.

A first fabric 68 is placed over the mold. The fabric covers the upper surface, and is folded down to cover part of the first side surface. It is also folded down to cover part of the second side surface. The first fabric is a glass fiber sheet, i.e. a sheet woven with threads of glass fiber.

In fig. 3B the first web-joint element 53 is placed on the first fabric at the first edge area. The first web-joint element has a first base, and a first connecting element. The first web-joint element is placed so that part of the first base is up against the first side surface (with part of the first fabric between the first base and the first side surface). This makes the first base parallel with the first side surface.

The first base and the first connecting element are joined by means of a first joint. The first joint is pivoted so that the first connecting element is parallel with the upper surface and rests against part of the first fabric on the upper surface.

Thus, the inclination of the first side surface and the horizontal upper surface defines a first angle, which the first joint will pivot to when the first web-joint element is placed at the first edge area.

Similarly, the second web-joint element 55 is placed on the first fabric at the second edge area. The second web-joint element has a second base, and a second connecting element. The second web-joint element is placed so that part of the second base is up against the second side surface (with part of the first fabric between the second base and the second side surface). This makes the second base parallel with the second side surface.

The second base and the second connecting element are joined by means of a sec- ond joint. The second joint is pivoted so that the second connecting element is parallel with the upper surface and rests against part of the first fabric on the upper surface.

Thus, the inclination of the second side surface and the horizontal upper surface defines a second angle, which the second joint will pivot to when the second web-joint el- ement is placed at the second edge area.

The two connecting elements face each other meaning that the tapered end of the first connecting element, and the tapered end of the second connecting element are closer to each other than other parts of the two connecting elements.

In fig. 3C a web constituted by a block of foam is placed in the mold on the first fabric. The web is between the tapered end of the first connecting element, and the tapered end of the second connecting element. In fig. 3D a second fabric 70 is placed on the first web-joint element, the web, and the second web-joint element. The assembly is assembled such that the first web-joint element, the web, and the second web-joint element are sandwiched between the first fabric and the second fabric. Thus, each side of the first connecting element is provided with fabric, and the part of the first base (which is opposite the bottom surface of the first base) is also provided with fabric. Similarly, each side of the second connecting element is provided with fabric, and the part of the second base, (which is opposite the bottom surface of the second base) is also provided with fabric. The assembly is now to be arranged into an interconnected structure constituting the shear web. This is done with a curable infusion material in a vacuum assisted infusion process, which is explained in connection with fig. 3E

The curable infusion material may be a polymer such as an epoxy resin.

In fig. 3E, a vacuum bag 80 is placed over the assembly. The vacuum bag has an edge, which may be connected to the side surfaces of the mold with tape.

A vacuum is established in the bag so that the bag follows the contour of the assem- bly. The vacuum may be established by cutting a hole in the bag at the tip end of the mold, and sucking the air out of the hole using a tube connected to a vacuum pump.

Another hole may be made in the bag at the hub end of the mold in order to let the curable infusion material into the bag. The infusion material is in fluid state and is sucked into the bag with the vacuum pump. The infusion material flows into the fabric and in any gaps between parts of the assembly, for example due to the protrusion in the base joint part there is a gap between the base joint part and the connecting joint part. This gap will also be filled with infusion material. The infusion material is set to cure. This may take a number of hours, such as 24 hours at room temperature. Each of the first fabric and the second fabric are in the curing process turned into glass fiber reinforced polymer.

When the infusion material has cured, any excess glass fiber reinforced polymer may be separated for example by cutting. Fig. 3F shows the shear web, which has been removed from the mold. The first joint angle as well as the second joint angle varies along the length of the shear web. Also the height of the shear web varies along the length of the shear web. The shear web is placed on a first half shell of the blade by adhering the bottom surface of the first base to the interior surface of the blade shell. An adhesive material is placed on the bottom surface of the second base, and the two half shells are put together. In the following, the position of the shear web in the blade is explained in more detail.

Fig. 4 shows a wind turbine blade 12 mounted on a rotor hub 36 of a wind turbine (the tower and nacelle of the wind turbine is not shown in fig. 4). Part of two other wind turbine blades mounted on the rotor hub are also visible in fig. 4. The wind turbine blade has a hub end 38, which is proximal to the hub and comprises fixtures for connecting the blade to the hub. The blade has a tip end 40 opposite the hub end.

The blade span is from the hub end to the tip end, i.e. the blade axis extends in a span wise direction through the hub end and the tip end.

The blade rotates in a clockwise direction and has a leading edge 42, which is rounded, i.e. the curve defining the shape of the leading edge in the blade cross section is differentiate. Opposite the leading edge is a trailing edge 44, which has an acute internal angle smaller than that of the leading edge.

The cross section AA' is closer to the tip end than the two other cross sections BB' and CC. The cross section CC is closer to the hub end than the two other cross section AA' and BB'. The cross section is between the cross sections AA' and CC and located approximate the middle of the blade.

The blade has two shear webs (46,48) placed in the interior for providing structural stability to the blade (not shown in fig. 4). The two shear webs extend substantially parallel to each other along a major part of the blade span, i.e. they do not extend all the way to the tip end and also not all the way to the hub end. The two shear webs extend approximately 90 % of the blade span. Fig. 5A shows the cross section AA' of the blade in fig. 4. The cross section is in a plane orthogonal to the span of the blade, i.e. it is a blade cross section. The blade is made from two half shells made in two molds.

The first half shell has a first edge defining a blade plane 50, and the second half shell has a second edge - the two half shells are put together by placing the two edges in contact with each other. An adhesive material is used to adhere the shells together. The blade plane is shown as a dotted line.

The shells define a hollow interior space. The blade does not have any panels, spar caps or shear webs in the interior where the cross section AA' is taken.

The path from the leading edge to the trailing along the upper outer side of the blade is shorter than the path from the leading edge to the trailing along the lower outer side of the blade.

Thus, air traveling along the upper side travels at a lower speed than the air traveling along the lower side, and there is a higher pressure on the upper side than on the lower side. The upper side is termed the pressure side 47, and the lower side is termed the suction side 49.

Fig. 5B shows the cross section BB' of the blade in fig. 4. The cross section is in a plane orthogonal to the span of the blade, i.e. it is a blade cross section. In the cross section, the two shear webs can be seen.

A total of four web joints are used to attach the two shear webs to the blade and provides an assembly, which enhances the structural rigidity compared to a situation without such an assembly. A close up of a first web joint with a first base 52 and a first connecting element 56 is also shown.

The shear web closest to the leading edge is termed the leading shear web 46, and the shear web closest to the trailing edge is termed the trailing shear web 48.

Fig. 5C shows the cross section CC of the blade in fig. 4. The cross section is in a plane orthogonal to the span of the blade, i.e. it is a blade cross section. In the cross section, the two shear webs also shown in fig. 5B can be seen. Again a close up of the first web joint in the CC cross section is also shown.

As mentioned, large wind turbines comprise blades with spans of up to 100 m, and the two shear webs extend along a major part of the span, which is why both shear webs can be seen in both the cross section BB' and CC.

Since the blade profile (the shape of the blade cross section) or at least the dimension of the blade varies along the span of the blade, and the assembly extends along a major part of the span, the assembly has to adapt to the varying blade profile while enhancing the structural stability.

In cross section BB' the height of both shear webs is smaller than the height of the shear web in cross section CC.

A first base 52 is placed with the bottom surface facing a first inner side of the interior surface of blade (the inner side defined by the upper/pressure half shell of the blade). An adhesive material is sandwiched between the bottom surface and the interior surface for adhering the first base to the interior surface.

The first base extends along a major part of the span of the blade. Since the blade profile varies, the bottom surface of the first base has a first angle in cross section BB' and a second angle in cross section CC - the two angles being different. In cross section BB' the first base is more horizontal than in cross section CC, where it has an inclination.

A second base 54 is placed with the bottom surface facing a second inner side of the interior surface of blade (the inner side defined by the lower/suction half shell of the blade). An adhesive material is sandwiched between the bottom surface and the interior surface for adhering the second spar cap to the interior surface.

The projection with the two striped lines in fig. 5B shows that the second base is placed so that at least part of the second base overlaps a part of a mirror projection (in the blade plane) of the first base onto the suction half shell. A first connecting joint part of a first connecting element is placed in a first base joint part of the first base. In fig. 5B, the rounded bearing end of the first connecting element is placed in the U-shaped bearing of the first base. A second connecting joint part of a second connecting element is placed in a second base joint part of the second base. In fig. 5B, the rounded bearing end of the second connecting element is placed in the U-shaped bearing of the second spar cap.

The tapered end of the first connecting element faces the tapered end of the second connecting element, i.e. the two connecting elements are aligned so that that there is the shortest possible distance between the tapered end of the first connecting element and the tapered end of the second connecting element.

Fig. 6 shows a blade cross section of a wind turbine blade, which only comprises a single shear web. As with the blade mentioned in connection with fig. 4, the shear web of the blade of fig. 6 is also attached to the blade using a number of web joints elements.

In the following is given a list of reference signs that are used in the detailed description of the invention and the drawing referred to in the detailed description of the invention.

10 Web joint element

1 1 Shear web

12 Wind turbine blade

14 Web

16 Base

18 Connecting element

20 Bottom surface

21 Protrusion

22 Interior surface

24 Base joint part

25 Connecting joint part

26 Tapered end

28 Bearing end

30 First side wall

32 Second side wall

34 First web end

36 Rotor hub

38 Hub end

40 Tip end

42 Leading edge

44 Trailing edge

46 Leading shear web

47 Pressure side

48 Trailing web

49 Suction side

50 Blade plane

52 First base

53 First web joint element

54 Second base

55 Second web joint element

56 First connecting element

58 Second connecting element Tip end of connecting element

Hub end of connecting element

Tip end of base

Hub end of base

First fabric

Second fabric

Vacuum bag

First edge

Second edge

Claims

1. A kit-of-parts for manufacturing a shear web for a wind turbine blade, said kit-of-parts comprising

2. The kit-of-parts according to claim 1 , comprising pultruding or extruding said base in a pultrusion or extrusion process respectively.

3. The kit-of-parts according to any of the preceding claims, comprising pultruding or extruding said connecting element in a pultrusion or extrusion process respectively.

4. The kit-of-parts according to any of the preceding claims, said base and/or said connecting element being manufactured from a fiber reinforced plastic.

5. The kit-of-parts according to any of the preceding claims, said joint being a cylindrical joint.

6. The kit-of-parts according to any of the preceding claims, said base joint part being U-shaped in a cross section orthogonal to a longitudinal axis of said base.

7. The kit-of-parts according to any of claims 1-5, said connecting joint part being U- shaped in a cross section orthogonal to a longitudinal axis of said connecting element.

8. A web joint element for joining a shear web of a wind turbine blade to an internal surface of said wind turbine blade, said web joint element comprising a base, and a connecting element, said base constituting a flange of web-joint element, and comprising a bottom surface for adhering to said internal surface of said wind turbine blade, and

a base joint part on the opposite side of said bottom surface, said connecting element constituting a web of said connecting element, and comprising a bearing end, said bearing end having a connecting joint part for cooperating with said base joint part for providing a joint.

9. A method of manufacturing a shear web for a wind turbine blade, said method comprising:

providing a first web joint element encompassing

a first base with a first base joint part, and

providing a second web joint element encompassing

a second base with a second base joint part, and

providing in said mold an assembly comprising

- a first fabric on said mold surface,

- a web placed on said first fabric between said first web joint element and said second web joint element, - a second fabric placed on said first web joint element, said web, and said second web joint element such that said first web joint element, said web, and said second web joint element being sandwiched between said first fabric and said second fabric, providing a curable infusion material in fluid form, and infusing said curable infu- sion material in said assembly, and curing said curable infusion material.

10. The method according to claim 9, said first fabric and/or said second fabric being a pre-impregnated composite fiber.

1 1 . The method according to claim 9, comprising rolling said first base up in a first roll.

12. The method according to claim 9, comprising rolling said first connecting element up in a second roll.

13. A shear web for a wind turbine blade, said shear web comprising:

a first web joint element encompassing

a first base with a first base joint part, and

a second web joint element encompassing

a second base with a second base joint part, and

said first connecting element facing said second connecting element,

said shear web further comprising

a web between said first connecting element and said second connecting element,

said first fabric, said second fabric, said first web joint element, said second web joint element, and said web being fixed to each other by means of an infusion material.