MALE SPAR BEAM FOR A SEGMENTED WIND TURBINE BLADE

Abstract

A male spar beam for mutually attaching a segmented wind turbine blade and, comprising: a leading-edge part comprising a second upper wall, a second lower wall, and a second shear wall connecting the second upper wall with the second lower wall, the leading-edge part; and a trailing-edge part comprising a first upper wall, a first lower wall, and a first shear wall connecting the first upper wall with the first lower wall. The leading-edge and trailing-edge parts being separately formed integrally in one piece, respectively. An end of the first lower wall is attached to an end of the second lower wall so that the first lower wall and the second lower wall form a lower spar cap of the male spar beam, and an end of the first upper wall is attached to an end of the second upper wall so that the first upper wall and the second upper wall form an upper spar cap of the male spar beam.

Claims

1. A male spar beam for engaging with a female receiving section of a first blade segment of a segmented wind turbine blade and for attachment to a second blade segment of the segmented wind turbine blade and, the segmented wind turbine blade having a profiled contour including a pressure side and a suction side, and a leading edge and a trailing edge with a chordwise direction extending therebetween, the segmented wind turbine blade extending in a longitudinal direction from a root end to a tip end thereof, wherein the male spar beam extends in a longitudinal direction extending from a first end to a second end thereof, the second end being configured for engaging with the female receiving section of the segmented wind turbine blade, and wherein the male spar beam comprises: an upper spar cap extending in the longitudinal direction, having a width bounded by a left upper boundary and a right upper boundary, and having an upper joint arranged between the left upper boundary and the right upper boundary, and being configured for facing one of the pressure side and the suction side of the segmented wind turbine blade; a lower spar cap extending in the longitudinal direction, and having a width bounded by a left lower boundary and a right lower boundary, having a lower joint arranged between the left lower boundary and the right lower boundary, and being configured for facing the other one of the pressure side and the suction side of the segmented wind turbine blade, the lower spar cap being positioned opposite of and extending in parallel to the upper spar cap; a leading-edge part comprising a first upper wall, a first lower wall, and a first shear wall connecting the first upper wall with the first lower wall, the leading-edge part being formed integrally in one piece and preferably comprising a fibre-reinforced laminate material, such as a carbon or glass fibre-reinforced laminate material; and a trailing-edge part comprising a second upper wall, a second lower wall, and a second shear wall connecting the second upper wall with the second lower wall, the trailing-edge part being formed integrally in one piece separately from the leading-edge part and preferably comprises a fibre-reinforced laminate material, such as a carbon or glass fibre-reinforced laminate material; wherein an end of the first lower wall of the leading-edge part is attached, preferably adhesively, to an end of the second lower wall of the trailing-edge part to form the lower joint so that the first lower wall and the second lower wall form the lower spar cap of the male spar beam, and wherein an end of the first upper wall of the leading-edge part is attached, preferably adhesively, to an end of the second upper wall of the trailing-edge part to form the upper joint so that the first upper wall and the second upper wall form the upper spar cap of the male spar beam.

2. A male spar beam according to claim 1, wherein the upper joint and/or the lower joint is positioned at a position in the range of 5%-95% of the width of the upper spar cap and/or the lower spar cap, respectively, preferably in the range of 10%-90%, more preferably in the range of 20%-80%, even more preferably in the range of 30%-70%, or most preferably in the range of 40%-60% of the width of the upper spar cap and/or the lower spar cap.

3. A male spar beam according to claim 1 further comprising an upper interior strip and/or a lower interior strip, the interior strip(s) preferably being manufactured separately from the leading-edge part and the trailing-edge part, wherein the upper interior strip is attached, preferably by an adhesive, to and overlaps an interior surface of the first upper wall of the leading-edge part and an interior surface of the second upper wall of the trailing-edge part, and/or wherein the lower interior strip is attached, preferably by an adhesive, to and overlaps an interior surface of the first lower wall of the leading-edge part and an interior surface of the second lower wall of the trailing-edge part.

4. A male spar beam according to claim 1 further comprising a first shear web part having a third shear wall attaching, preferably adhesively, the upper interior strip to the lower interior strip, the first shear web part being manufactured separately from the leading-edge part and the trailing-edge part, and the third shear wall is preferably formed integrally in one piece with the upper interior strip and the lower interior strip.

5. A male spar beam according to claim 1 further comprising an upper exterior strip and/or a lower exterior strip, the exterior strips preferably being manufactured separately from the leading-edge part and the trailing-edge part, wherein the upper exterior strip is attached, preferably adhesively, to and overlaps an exterior face of the first upper wall of the leading-edge part and an exterior face of the second upper wall of the trailing-edge part, and/or wherein the lower exterior strip is attached, preferably adhesively, to and overlaps an exterior face of the first lower wall of the leading-edge part and an exterior face of the second lower wall of the trailing-edge part.

6. A male spar beam according to claim 1 further comprising an engagement member, such as a bolt or pin, protruding from the second end of the male spar beam, the engagement member being configured for being inserted into and engaging with the female receiving section of the segmented wind turbine blade.

7. A male spar beam according to claim 1, wherein the first shear wall of the leading-edge part comprises an at least partially embedded first reinforcement structure, such as a ring, including a first receiving portion, such as a hole or cut-out, and preferably the second shear wall of the trailing-edge part comprises an at least partially embedded second reinforcement structure, such as a ring, including a second receiving portion, such as a hole or cut-out, preferably being aligned with the first receiving portion, wherein the first reinforcement structure and/or the second reinforcement structure comprise a metal, and the first receiving portion and/or the second receiving portion forming part of a locking arrangement of the segmented wind turbine blade and being configured for receiving an engagement element of the locking arrangement, such as a pin, thereby mutually locking the segmented wind turbine blade.

8. A segmented wind turbine blade having a profiled contour including a pressure side and a suction side, and a leading edge and a trailing edge with a chord extending therebetween, the segmented wind turbine blade extending in a longitudinal direction between a root end and a tip end, the segmented wind turbine blade comprising a first blade segment having a female receiving section, and a second blade segment having a male spar beam according to any one of the previous claims configured for insertion into and engaging with the female receiving section of the first blade segment.

9. A segmented wind turbine blade according to claim 8, wherein the female receiving section defines an inner cavity and has a longitudinal inner end and an opposite longitudinal open end at an end face of the first blade segment, wherein the second blade segment is connected to the first blade segment at a chord-wise joint, the male spar beam protruding at the chord-wise joint from an end face of the second blade segment and extending through the longitudinal open end of and into the cavity of the female receiving section to be received therein, thereby attaching the first blade segment to the second blade segment, the segmented wind turbine blade additionally comprises locking arrangement mutually locking the female receiving section and the male spar beam and thereby the first and second blade segment.

10. A method of manufacturing a male spar beam for a wind turbine blade, comprising the steps of: providing a pre-cured trailing-edge part comprising a first upper wall, a first lower wall, and a first shear wall connecting the first upper wall with the first lower wall; providing a pre-cured leading-edge part comprising a second shear wall, a second upper wall and a second lower wall, wherein the cured leading-edge part is provided separately from the cured trailing-edge part; and forming the male spar beam by attaching, preferably adhesively, the first upper wall of the leading-edge part to the second upper wall of the trailing-edge part via an upper joint to form an upper spar cap of the male spar beam, and attaching, preferably adhesively, the first lower wall of the leading-edge part to the second lower wall of the trailing-edge part via a lower joint to form a lower spar cap of the male spar beam.

11. A method according to claim 10, wherein the step of providing the pre-cured trailing-edge part comprises a sub-method of manufacturing the leading-edge part including the steps of: providing a first fibre material, such as glass or carbon fibres, and preferably one or more first elongated fibre-reinforced elements, and a first female mould with a first mould surface having a first left wall face, a first floor face, and a first right wall face arranged opposite of the first left wall face, the first wall faces extending upwards from the first floor face; arranging the first fibre material and preferably the one or more first elongated fibre-reinforced elements on the first mould surface of the first mould; preferably infusing the first fibre material, and preferably co-infusing the one or more first elongated fibre-reinforced elements, with a first resin material, such as an epoxy or a polyester, preferably by a vacuum assisted resin infusion process; and curing the first fibre material, and preferably the one or more first elongated fibre-reinforced elements, to provide the pre-cured leading-edge part in one piece; and/or wherein the step of providing a pre-cured trailing-edge part comprises a sub-method of manufacturing the trailing-edge part including the steps of: providing a second fibre material, such as glass or carbon fibres, and preferably one or more second elongated fibre-reinforced elements, and a second female mould with a second mould surface having a second left wall face, a second floor face, and a second right wall face arranged opposite of the second left wall face, the second wall faces extending upwards from the second floor face; arranging the second fibre material and preferably the one or more second elongated fibre-reinforced elements on the second mould surface of the second mould; preferably infusing the second fibre material, and preferably co-infusing the one or more second elongated fibre-reinforced elements, with a second resin material, such as an epoxy or a polyester, preferably by a vacuum assisted resin infusion process; and curing the second fibre material, and preferably the one or more second elongated fibre-reinforced elements, to provide the pre-cured trailing-edge part in one piece; wherein the first fibre material, the one or more first elongated fibre-reinforced elements, and the first mould are different from the second fibre material, the one or more second elongated fibre-reinforced elements, and the second mould, respectively.

12. A method according to claim 10, wherein the step of providing the pre-cured leading-edge part comprises arranging a first reinforcement structure, such as one or more first disks or rings, in the first fibre material on the first lower face of the first mould and wherein the step of infusing the first fibre material comprises co-infusing the first reinforcement structure, and/or wherein the step of providing the pre-cured trailing-edge part comprises arranging a second reinforcement structure, such as one or more second disks or rings, in the second fibre material on the second lower face of the second mould and wherein the step of infusing the second fibre material comprises co-infusing the second reinforcement structure, and wherein the method preferably further comprises a step of providing a first receiving portion, such as a hole or a cut-out, in the first reinforcement structure and/or a step of providing a second receiving portion, such as a hole or a cut-out, in the second reinforcement structure, the second receiving portion preferably being aligned with the first receiving portion, the first receiving section and/or the second receiving section forming part of a locking arrangement of the segmented wind turbine blade and being configured for receiving an engagement element of the locking arrangement, such as a pin, thereby mutually locking the segmented wind turbine blade.

13. A method according to claim 10 further comprising a step of: providing an upper exterior strip and/or a lower exterior strip, the exterior strips preferably being manufactured separately from the leading-edge part and the trailing-edge part, the first exterior strip and/or the second exterior strip preferably comprising a fibre laminate, optionally being either cured or uncured, and wherein the method further comprising a step of: overlapping and attaching, preferably adhesively, the first exterior strip to an exterior face of the first upper wall of the leading-edge part and an exterior face of the second upper wall of the trailing-edge part, and/or overlapping and attaching, preferably adhesively, the second exterior strip to an exterior face of the first lower wall of the leading-edge part and an exterior face of the second lower wall of the trailing-edge part.

14. A method according to claim 10 further comprising the steps of: providing an upper interior strip and/or a lower interior strip, the interior strip(s) preferably being manufactured separately from the leading-edge part and the trailing-edge part, the exterior strip(s) preferably comprise(s) a cured or uncured fibre laminate, and overlapping and attaching, preferably adhesively, the upper interior strip to an interior surface of the first upper wall of the leading-edge part and an interior surface of the second upper wall of the trailing-edge part, and/or overlapping and attaching, preferably adhesively, the lower interior strip to an interior surface of the first lower wall of the leading-edge part and an interior surface of the second lower wall of the trailing-edge part.

15. A method according to the claim 14, wherein the step of providing the upper interior strip and the lower interior strip further comprises providing a first shear web part having a third shear wall attaching, preferably adhesively, the upper interior strip to the lower interior strip, preferably the third shear wall being formed integrally with the upper interior strip and the lower interior strip in one piece.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Embodiments of this disclosure will be described in more detail in the following with regard to the accompanying figures. The figures show one way of implementing the present invention and are not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

[0092] FIG. 1 is a schematic perspective view of a wind turbine.

[0093] FIG. 2 is a schematic perspective view of a segmented wind turbine blade.

[0094] FIG. 3a is a schematic side view of a segmented wind turbine blade.

[0095] FIG. 3b is a schematic view of a tip segment for a segmented wind turbine blade.

[0096] FIG. 3c is a schematic view of a root segment for a segmented wind turbine blade.

[0097] FIG. 4a is a schematic view of a male spar beam for a pin joint in a segmented wind turbine blade.

[0098] FIG. 4b is a schematic view of a female receiving section for a pin joint in a segmented wind turbine blade.

[0099] FIG. 4c is a schematic view of a pin joint female receiving section mated with a corresponding pin joint spar beam.

[0100] FIG. 5a is a schematic cross-sectional view of a male spar beam incorporated in a blade segment.

[0101] FIG. 5b is a schematic cross-sectional view of a female mould for moulding a leading-edge part or trailing edge-part of the male spar beam.

[0102] FIG. 6a is a schematic side view of a reinforcement arrangement for use in moulding of the male spar beam.

[0103] FIG. 6b is a schematic view of a step of arranging elongated fibre-reinforced elements and fibre material in the female mould.

[0104] FIG. 7a is a schematic perspective view of a step of incorporating a reinforcement structure in a shear wall during manufacture of the male spar beam.

[0105] FIG. 7b is a schematic cross-sectional view of FIG. 7a

[0106] FIG. 8a is a schematic view of a step of infusing the leading-edge part by a vacuum assisted resin transfer process.

[0107] FIG. 8b is a schematic view of a step of removing the leading-edge part from the first mould after curing thereof.

[0108] FIG. 9a is a schematic cross-sectional view of a third female mould for moulding a first shear web part.

[0109] FIG. 9b is a schematic cross-sectional view of a step of attaching the first shear web part to the leading-edge part.

[0110] FIG. 10a is a schematic cross-sectional view of the male spar beam after assembly.

[0111] FIG. 10b is a schematic cross-sectional view of the male spar beam illustrating the distribution of shear stresses on the male spar beam.

[0112] FIG. 11 is a schematic cross-sectional view of the male spar beam with additional shear web parts and walls incorporated therein.

DETAILED DESCRIPTION OF THE INVENTION

[0113] FIG. 1 illustrates a conventional modern upwind wind turbine 2 according to the so-called “Danish concept” with a tower 4, a nacelle 6 and a rotor with a substantially horizontal rotor shaft. The rotor includes a hub 8 and three blades 10 extending radially from the hub 8, each having a blade root 16 nearest the hub and a blade tip 14 farthest from the hub 8.

[0114] FIG. 2 shows a schematic view of a wind turbine blade 10. The wind turbine blade 10 has the shape of a conventional wind turbine blade and comprises a root region 12 closest to the hub, a profiled or an airfoil region 11 farthest away from the hub and a transition region 13 between the root region 12 and the airfoil region 11. The blade 10 comprises a leading edge 18 facing the direction of rotation of the blade 10, when the blade is mounted on the hub, and a trailing edge 20 facing the opposite direction of the leading edge 18. The outermost point of the blade 10 is the tip end 15.

[0115] The airfoil region 11 (also called the profiled region) has an ideal or almost ideal blade shape with respect to generating lift, whereas the root region 12 due to structural considerations has a substantially circular or elliptical cross-section, which for instance makes it easier and safer to mount the blade 10 to the hub. The diameter (or the chord) of the root region 12 may be constant along the entire root area. The transition region 13 has a transitional profile gradually changing from the circular or elliptical shape of the root region 12 to the airfoil profile of the airfoil region 11. The chord length of the transition region 13 typically increases with increasing distance r from the hub. The airfoil region 11 has an airfoil profile with a chord extending between the leading edge 18 and the trailing edge 20 of the blade 10. The width of the chord decreases with increasing distance r from the hub 8.

[0116] A shoulder 26 of the blade 10 is defined as the position where the blade 10 has its largest chord length. The shoulder 26 is typically provided at the boundary between the transition region 13 and the airfoil region 11. The outermost third of the airfoil region 11 is typically referred to as the tip region 11′. FIG. 2 also illustrates the longitudinal direction L defining longitudinal extent of the blade.

[0117] FIG. 3a schematically illustrates a segmented wind turbine blade 10. It is made up at least of a root segment 27 and a tip segment 29 divided at a chordwise joint. To allow joining of the root segment 27 with the tip segment 29, the two segments 27, 29 may comprise a female receiving section 28 and a mating male spar beam 30 inserted into and engaging with the female receiving section 28. The female receiving section 28 and the male spar beam 30 are fixed together via a locking arrangement, see FIGS. 4a-4c, at the chordwise joint with a pin.

[0118] FIG. 3b illustrates the tip segment 29 of the segmented blade 10 shown in the previous figures. Aside from the shell that forms the aerodynamic profile of the blade 10, the tip segment 29 further comprises the male spar beam 30 as described above. The male spar beam 30 of the tip segment protrudes beyond (outside) the tip segment shell at the chordwise joint to allow the male spar beam to engage with a corresponding female receiving section 28 arranged in the root segment 27.

[0119] FIG. 3c illustrates the root segment 27 of the segmented blade 10. As described above, the root segment 27 comprises a female receiving section 28 for receiving the male spar beam 30 of the tip segment 29 in order to allow the root segment 27 and the tip segment 29 to be securely joined together. The final blade is obtained by mating the male spar beam 30 with the female receiving section 28, securing the two together at the chordwise joint, sealing the region where the blade segments 27, 29 meet, and providing any finishing touches to the blade.

[0120] FIG. 4a is a schematic illustration of a male spar beam 30 for a pin joint for a segmented wind turbine blade 10. In addition to the beam as such, the male spar beam has reinforcement structures each having a receiving portion 94, 98 in the form of holes for receiving a pin. Furthermore, this spar beam 30 has an engagement member 38 in the form of a bolt that will engage with a receiving portion 28b in the form of a slot in the female receiving section 28 to improve stability, see FIGS. 4b-4c. This contributes to reducing unwanted motion between the male spar beam 30 and the female receiving section 28 during use.

[0121] FIG. 4b is a schematic illustration of a female receiving section 28 for engaging with the male spar beam 30 shown in FIG. 4a. The female receiving section 28 defines an inner cavity and has a longitudinal inner end 28a and an opposite longitudinal open end 28c at an end face of the first blade segment 27. Like the male spar beam 30, the female receiving section 28 comprises receiving portions 28d, 28e in the form of holes for receiving a pin. The inner end 28a is provided in the form of a plate with a slot 28b configured to fit tightly with the engagement member 38 of the male spar beam 30. When the engagement member 38 is engaged with the slot 28b, chordwise movement of the male spar beam relative to the female receiving section 28 is inhibited. The position of slot 28b, receiving portions 28d, 28e, 94, 98, and the shape and size of the male spar beam 30 and the female receiving section 28 are not essential for the present invention.

[0122] FIG. 4c shows the female receiving section 28 and male spar beam 30 engaged, with the male spar beam 30 inserted through the longitudinal open end 28c of and into the cavity of the female receiving section 28 to be received therein. The engagement member 38 is engaged with the receiving portion 28b of the female receiving section 28 to prevent chordwise movements. An engagement element 99 is shown engaging with receiving portions 28d, 28e, 94, 98 to mutually lock the tip segment 27 and the root segment 29 and maintaining joint connection under centrifugal/centripetal forces.

[0123] FIG. 5a illustrates the male spar beam 30 incorporated into the segmented wind turbine blade 10 in a cross-sectional view. The male spar beam 30 is arranged in the interior cavity of the segmented wind turbine blade. The male spar beam extends in three mutually perpendicular directions: a longitudinal direction (extending in and out of plane on FIG. 5a), a lateral direction (extending from left-right on FIG. 5a) and a thickness direction (extending up-down on FIG. 5a). The longitudinal direction of the male spar beam is parallel to the longitudinal direction of the segmented wind turbine blade 10. The lateral direction is parallel to the chordwise direction of the segmented wind turbine blade 10. The thickness direction is parallel to a thickness direction of the segmented wind turbine blade 10 extending between the suction side and the pressure side of the segmented wind turbine blade 10.

[0124] Furthermore, the male spar beam 30 comprises an upper spar cap 40 adjacent to the suction side 24 and extending in the longitudinal direction. The upper spar cap 40 has a width bounded by a left upper boundary 42 and a right upper boundary 44 thereof. The upper spar cap 40 has an upper joint 34 connecting two halves of the upper spar cap 40. The upper joint 34 is arranged between the upper boundaries 42, 44. The male spar beam 30 further comprises a lower spar cap 46 adjacent to the pressure side 22 and is positioned opposite of and extending in parallel to the upper spar cap 40. The lower spar cap 46 has a width bounded by a left lower boundary 48 and a right lower boundary 49 thereof. The lower spar cap 46 has a lower joint 35 arranged between the left lower boundary 48 and the right lower boundary 49. The wind turbine blade 10 may typically, in addition to the male spar beam 30, comprise additional spar caps (often embedded in the shells) with one or more connecting shear webs. There may be some overlap between these additional spar caps embedded in the shells and the spar caps of the male spar beam 30.

[0125] In the present embodiment, the male spar beam 30 is made of three separately manufactured fibre-reinforced laminate composite parts: a leading-edge part 50, a trailing-edge part 60, and a first shear web part 70. An example of a method of manufacturing such a male spar beam is now described in more detail.

[0126] FIG. 5b schematically illustrates a female mould 100 with a mould surface 101 having a left wall face 102 for forming a part of a spar cap, a floor face 103 for forming a shear wall, a right wall face 104 for forming a part of a different spar cap, a left flange face 105 adjacent to the first left wall face 102, and a right flange face 106 adjacent to the first right wall face 104. The right wall face 104 is arranged opposite of the left wall face 102. The wall faces 102, 104 extend upwards from the floor face 103. The wall faces 102, 104 may have a slight positive draft angle to ease removal of the moulded part. The female moulds 100 for the leading-edge part 50 and the trailing-edge part 60 is in this case substantially the same with some dimensional differences to fit to the specific segmented blade 10.

[0127] FIG. 6a schematically illustrates a reinforcement arrangement 200 provided to form the main load-carrying structure of the spar caps. The reinforcement arrangement 200 comprises a plurality of elongated fibre-reinforced elements in the form of pultrusions 201 and a plurality of threads 202 suspending the pultrusions 201 in a parallel orientation from an end 203 of each thread 202 as shown.

[0128] Both of the leading-edge part 50 and the trailing-edge part 60 can be separately moulded in the following way. As best seen in FIG. 6a, a fibre material 300, e.g. a glass fibre sheet, is laid up to cover the left wall face 102, the floor face 103, and the right wall face 104 of the female mould 100. Then a reinforcement arrangement 200 as previously shown is lowered into the female mould 100 and the ends 203 of the threads 202 are attached to the left flange face 105 of the female mould 100 to hang the pultrusions 201 along the fibre material 300 laid against the left wall face 102 of the female mould 100. This is repeated with another reinforcement arrangement 200 which is hung from the right flange face 106 against the fibre material laid against the right wall face 104.

[0129] If reinforcement structures are desired in the male spar beam 30, then such a reinforcement structure 92 may be incorporated as shown in FIGS. 7a-7b. A reinforcement structure 92 in the form of a disk or ring may be arranged on the fibre material 300 (shown transparent in FIG. 7a to allow other elements to be seen) laid against the floor face 103 of the female mould 100. Such a reinforcement structure 92 may comprise a receiving portion for a pin or bolt or such a receiving portion, as in this case, may be provided, e.g. cut, after moulding of the respective part 50, 60.

[0130] The reinforcement arrangements 200 previously placed, and any reinforcement structures, may then be covered by additional fibre material 300, e.g. glass fibre sheets. Additional reinforcement arrangements 200 may be placed in the female mould 100 in the same way as previously described and then covered by additional fibre material 300. Preferably, there is at least one layer of fibre material 300 between adjacent reinforcement arrangements 200. This arrangement is best schematically seen in FIG. 8a. If the fibre material 300 is not pre-impregnated, a bag 107 may instead seal the female mould 100 and is connected to a vacuum source 108, e.g. a pump. The respective part 50, 60 is then infused using a vacuum assisted resin transfer infusion process. If the fibre material is pre-impregnated, it may be cured in an oven or an autoclave.

[0131] After curing, the part can be removed from the female mould 100. FIG. 8b illustrates this after curing of the leading-edge part 50 in the respective female mould 100. The step is substantially the same for removing the trailing-edge part 60 from its female mould. As seen, leading-edge part 50 is C-shaped or [-shaped in a cross-section perpendicular to the longitudinal direction as illustrated in FIG. 8b. After removal, the leading-edge part 50 and correspondingly the trailing-edge part 60 can be separately inspected for e.g. quality defects, and further components can be installed in the interior space, e.g. on the interior surface 56.

[0132] The first shear web part 70 is manufactured in a third female mould 100c as shown in FIG. 9a separately from the leading-edge part 50 and the trailing-edge part 60. The third female mould 100c is of the same type as the previously described female mould 100 only differing in dimensions, i.e. being shorter in height and width and having a neutral draft angle. The process of moulding the first shear web part 70 is the same as for the leading-edge part 50 and trailing-edge part 60. The first shear web part 70 is integrally moulded in one piece to comprise an upper interior strip 71, lower interior strip 72, and a third shear wall 73 connecting the upper interior strip 71 and the lower interior strip 72. The upper interior strip 71 moulded against the left wall face 102c of the third female mould 100c. The lower interior strip 72 is moulded against the right wall face 104c of the third female mould 100c. The third shear wall 73 is moulded against the floor face 103c of the third female mould 100c. In some cases, the interior strips 71, 72 and third shear wall 73 may be moulded separately but in this case, the first shear web part 70 is a composite laminate structure, e.g. consisting substantially of glass fibres and polyester resin, but may in other cases comprise carbon fibres and/or pultrusions. After moulding, the first shear web part 70 can be separately inspected for e.g. quality defects.

[0133] The first shear web part 70 can now be attached to the leading-edge part 50 or the trailing edge-part 60. The case of attaching to the leading-edge part 50 is illustrated in FIG. 9b, but the case of attaching to the trailing-edge part 60 is substantially the same. As shown in FIG. 9b, the first shear wall 53 of the leading-edge part 50 is arranged to rest on a work surface (not shown) so that the leading-edge part forms a U-shape as shown. An adhesive 37 is then applied to the interior surface 56 adjacent to the end 54 of the first upper wall 51 and adjacent to the end 55 of the first lower wall 52. The first shear web part 70 is then lowered with its shear wall 73 first into the leading-edge part 50 between the ends 54, 55 of the first walls 51, 52 so that the upper interior strip 71 partially overlaps with the first upper wall 51 and the lower interior strip 72 partially overlaps with the first lower wall 52. The shear web part is then brought into contact with the adhesive 37 to adhere the upper interior strip 71 to the first upper wall 51 and the lower interior strip 72 to the first lower wall 52, thereby adhering the first shear web part 70 to the leading-edge part 50 to form a sub-assembly. When the sub-assembly of the leading-edge part 50 and first shear web part 70 have passed inspection, the trailing-edge part 60 can be gathered.

[0134] As illustrated in FIG. 10a, an adhesive, optionally different from the previously used, is then applied to the ends 54, 55 of the first walls 51, 52, and optionally to the free ends of the interior strips 71, 72. Ends 64, 65 of the second walls 61, 62 of the trailing-edge part 60 are then brought into contact with said adhesive on the ends 54, 55 of the first walls 51, 52 of the leading-edge part 50 to form an upper adhesive butt joint 34 and a lower adhesive butt joint 35 thereby attaching the trailing-edge part 60 to the sub-assembly having the leading-edge part 50 and the first shear web part 70. Thus, the first upper wall 51 and the second upper wall 61 connected by the upper joint 34 form an upper spar cap 40 of the male spar beam 30, and the first lower wall 52 and the second lower wall 62 connected by the lower joint 35 form a lower spar cap 46 of the male spar beam 30. Prior to assembly with the leading-edge part 50, a lightning protection component 36 in the form of a down conductor was installed in the trailing-edge part 60. In this case, the upper joint 34 and the lower joint 35 are positioned at about half the width of the respective spar caps 40, 46 between their respective upper boundaries 42, 44 and lower boundaries 48, 49.

[0135] It should be noted that the order of manufacturing the leading-edge part 50 and the trailing-edge part 60 is not essential. Thus, the above described method of manufacturing could instead be the trailing-edge part 60 being manufactured first and the first shear web part 70 being attached thereto and the leading-edge part 50 being attached at the final steps to form the male spar beam 30.

[0136] To form the male spar beam 30, an upper exterior strip 81 is arranged to cover the exterior of the upper joint 34 and adhered exteriorly on the upper walls 51, 61 and a lower exterior strip 82 is arranged to cover the exterior of the lower joint 35 and adhered exteriorly on the lower walls 52, 62 thus arriving at the arrangement shown in FIG. 10a where the upper elements 51, 61, 71 are arranged upwards and the lower elements 52, 62, 72 are arranged downwards.

[0137] FIG. 10b illustrates the distribution of shear stress experienced by the male spar beam 30 during primary flapwise loading. As seen, the shear stress 39a is highest in the first shear wall 53 and second shear wall 63 while the shear stress 39b experienced by the spar caps 40, 46 tapers from the respective boundaries 42, 44, 48, 49 towards a midpoint between the respective boundaries 42, 44, 48, 49 of the spar caps 40, 46. As seen, the upper joint 34 and the lower joint 35 is arranged at the position of minimum shear stress to reduce the loading experienced by the joints 34, 35 (which is typically weaker than the remaining parts of the spar caps).

[0138] FIG. 11 illustrates another embodiment of a male spar beam 30 corresponding to the spar beam 30 previously described but differing in that the first shear web part 70 comprises a fourth shear wall 74 arranged opposite of the third shear wall 73 closing off the first shear web part 70 to define a box shape. This embodiment, further has an additional shear web part: a second shear web part 75 adhesively attaching the interior surface of the second upper wall 61 and the second lower wall 62 to provide additional shear stiffness and/or buckling strength, and a third shear web part 77 adhesively attaching the interior surface of the first upper wall 51 and the first lower wall 52 to provide additional shear stiffness and/or buckling strength. These additional shear web parts 75, 77 can be incorporated into the respective trailing-edge part 60 and the leading-edge part 50 prior to final assembly of the male spar beam 30 and is thus easy to incorporate.

TABLE-US-00001 LIST OF REFERENCES  2 wind turbine  4 tower  6 nacelle  8 hub  10 segmented wind   turbine blade  11 airfoil region  11′ tip region  12 root region  13 transition region  14 blade tip  15 tip end  16 blade root  17 root end  18 leading edge  20 trailing edge  21 chordwise joint  22 pressure side  24 suction side  26 shoulder  27 root segment  28 female receiving section  28a inner end  28b receiving portion  28c open end  28d first receiving portion  28e second receiving portion  29 tip segment  30 male spar beam  32 first end  33 second end  34 upper joint  35 lower joint  36 lightning protection   component  37 adhesive  38 engagement   member  39 shear stress  40 upper spar cap  42 left upper boundary  44 right upper boundary  46 lower spar cap  48 left lower boundary  49 right lower boundary  50 leading-edge part  51 first upper wall  52 first lower wall  53 first shear wall  54 first upper wall end  55 first lower wall end  56 interior surface  60 trailing-edge part  61 second upper wall  62 second lower wall  63 second shear wall  64 second upper wall end  65 second lower wall end  70 first shear web part  71 upper interior strip  72 lower interior strip  73 third shear wall  74 fourth shear wall  75 second shear web part  77 third shear web part  81 upper exterior strip  82 lower exterior strip  90 locking arrangement  92 first reinforcement structure  94 first receiving portion  96 second reinforcement structure  98 second receiving portion  99 engagement element 100 female mould 101 mould surface 102 left wall face 103 floor face 104 right wall face 105 left flange face 106 right flange face 107 bag 108 vacuum source 300 fibre material 200 reinforcement arrangement 201 pultrusion 202 thread 203 end 300 fibre material