Methods for retrofitting or manufacturing a wind turbine blade or wind turbine blade part

Abstract

A wind turbine blade (10) for a horizontal axis wind turbine (2), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16) is disclosed. The wind turbine blade (10) comprises: a plurality of wind turbine blade parts that are assembled to form the wind turbine blade, the plurality of wind turbine blade parts comprising a first wind turbine blade part, wherein the first wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the first wind turbine blade part comprises an edge portion, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to a face of the laminate structure of the first wind turbine blade part and extends along the edge portion of the first wind turbine blade part.

Description

[0001] METHODS FOR RETROFITTING OR MANUFACTURING A WIND TURBINE BLADE OR WIND TURBINE BLADE PART

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a wind turbine blade as well as a wind turbine blade part. It further relates to a shear web for a wind turbine blade as well as a wind turbine blade shell part for a wind turbine blade. In addition to this, the invention relates to a method of fitting or retrofitting a wind turbine blade part with a reinforcement structure. The invention further relates to methods of manufacturing a wind turbine blade, manufacturing a wind turbine blade part, manufacturing a shear web for a wind turbine blade, as well as manufacturing a wind turbine blade shell part.

[0004] BACKGROUND OF THE INVENTION

[0005] Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and a rotor having a rotatable hub with one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.

[0006] The rotor blades generally include a suction side shell part (or downwind shell part) and a pressure side shell part (or upwind shell part) typically formed using molding processes that are bonded together at bond lines along the leading and trailing edges of the blade. Further, the pressure and suction shells are relatively lightweight and have structural properties (e.g., stiffness, buckling resistance and strength) which are not configured to withstand the bending moments and other loads exerted on the rotor blade during operation. Thus, to increase the stiffness, buckling resistance and strength of the rotor blade, the body shell is typically reinforced using one or more structural components (e.g. opposing spar caps with one or more shear web structures configured therebetween) that engage the inner pressure and suction side surfaces of the shell halves. Alternatively, the spar caps may be integrated in the shell parts. The spar caps are typically constructed of various materials, including but not limited to glass fibre laminate composites and / or carbon fibre laminate composites. The shell of the rotor blade is generally built around the spar caps of the blade by stacking layers of fibre fabrics in a shell mold. The layers are then typically infused together, e.g. with a thermosetting resin. Such rotor blades, however, are not without issues. The blade components, such as spar receiving sections, beam structures, shear webs and the like, are conventionally adhered to the shells by bonding pastes, such as adhesives. These bonding pastes would define a typical bonding line on the shell of the wind turbine blade. The bond lines of typical rotor blades are generally formed by applying a suitable bonding paste (i.e. adhesives) or compound along the bond line with a minimum designed bond width between the shell members. These bonding lines are a critical design constraint of the blades as a significant number of turbine blade field failures occur at the bond-line. For instance, the bonding lines concentrate stresses and strains on a portion of the beam structures and / or shear webs. The concentration of such stresses and strains in the regions of structural discontinuities e.g., material-material interfaces or material-air interfaces, is often shown to be an initiation point for structural failure or fracture of the wind turbine blade components, requiring relatively expensive and time-consuming repair operations. Accordingly, improved systems and methods for eliminating crack initiation on the shear web structure and other wind turbine components are desired.

[0007] It is therefore the object of the present disclosure to provide improved methods and systems that at least ameliorate some of the drawbacks found in prior art designs.

[0008] SUMMARY OF THE INVENTION

[0009] Thus, according to a first aspect, there is provided a wind turbine blade for a horizontal axis wind turbine, wherein the wind turbine blade extends in a longitudinal direction parallel to a longitudinal axis and having a tip end and a root end. The wind turbine blade comprises: a plurality of wind turbine blade parts that are assembled to form the wind turbine blade, the plurality of wind turbine blade parts comprising a first wind turbine blade part, wherein the first wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the first wind turbine blade part comprises an edge portion, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to a face of the laminate structure of the first wind turbine blade part and extends along the edge portion of the first wind turbine blade part.

[0010] From the solution, it is clear that the elongated reinforcement element is distinct from the layers and reinforcement fibres of the laminate structure. It is also clear that the reinforcement element is a fibre-based reinforcement structure. Further, it is clear that the reinforcement element is a drapeable reinforcement element that is configured to be draped along the edge of the wind turbine blade part.

[0011] The solution overcomes one or more of the shortcomings of the conventional systems and methods. In particular, the reinforcement structure, which can be co-infused or retrofitted to the wind turbine blade part, provides improvements in relation to the cracks forming in or propagating into the laminate structure of the wind turbine part or in bonds at the edge of the wind turbine part.

[0012] Similarly, according to a second aspect, there is provided a wind turbine blade part for a wind turbine blade for a horizontal axis wind turbine, wherein the wind turbine blade extends in a longitudinal direction parallel to a longitudinal axis and having a tip end and a root end, wherein the wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the first wind turbine blade part comprises an edge portion, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to a face of the laminate structure of the first wind turbine blade part and extends along the edge portion of the wind turbine blade part.

[0013] Similarly and more specifically, according to a third aspect, there is provided a shear web for a wind turbine blade for a horizontal axis wind turbine, wherein the wind turbine blade extends in a longitudinal direction parallel to a longitudinal axis and having a tip end and a root end, wherein the shear web extends between a tip end surface and a root end surface and is configured to be arranged between a pressure side shell part and a suction side shell part of the wind turbine blade such that it extends substantially in the longitudinal direction between a tip end surface facing the tip end and a root end surface facing the root end, wherein the shear web comprises a recess formed in at least one of the tip end surface and the root end surface, and wherein a reinforcement element, preferably an elongated reinforcement element, is secured along the recess to a laminate structure of the shear web.

[0014] Similarly and also more specifically, according to a fourth aspect, there is provided a wind turbine blade shell part for a wind turbine blade for a horizontal axis wind turbine, wherein the wind turbine blade extends in a longitudinal direction parallel to a longitudinal axis and having a tip end and a root end, wherein the wind turbine blade shell part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the laminate structure of the wind turbine blade shell part comprises a first glue surface, which is configured to be adhered to a second glue surface of a second wind turbine shell part, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to the first glue surface and extends along the edge portion of the wind turbine blade shell part. The fourth aspect also covers the general aspect of providing a reinforcement element to a glue surface of a first wind turbine blade part which is adhered to a second glue surface of a second wind turbine blade part. Thus, the aspect covers a wind turbine blade part for a wind turbine blade for a horizontal axis wind turbine, wherein the wind turbine blade extends in a longitudinal direction parallel to a longitudinal axis and having a tip end and a root end, wherein the wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the laminate structure of the wind turbine blade part comprises a first glue surface, which is configured to be adhered to a second glue surface of a second wind turbine part, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to the first glue surface and extends along the edge portion of the wind turbine blade part. The glue joint formed between the first wind turbine blade part and the second wind turbine blade part may for instance be between a blade shell and the web foot flange of a shear web, or as recited above between two blade shell part. In the latter example, the glue joint can be at the leading edge or the trailing edge of the blade.

[0015] According to a fifth aspect, there is provided a method of fitting or retrofitting a wind turbine blade part with a reinforcement structure, wherein the method comprises the steps of: providing a wind turbine blade part for a wind turbine blade for a horizontal axis wind turbine, wherein the wind turbine blade extends in a longitudinal direction parallel to a longitudinal axis and having a tip end and a root end, wherein the wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the first wind turbine blade part comprises an edge portion, securing a reinforcement element, preferably an elongated reinforcement element, to a face of the laminate structure of the first wind turbine blade part such that it extends along an edge portion of the wind turbine blade part.

[0016] Similarly, according to a sixth aspect, there is provided a method of manufacturing a wind turbine blade part, wherein the method comprises the steps of: providing a layup including laying up layers including at least a first fibre-reinforced layer to form a laminate structure; infusing the laminate structure with a resin; curing the resin to form the wind turbine blade part including the laminate structure with the at least first fibre-reinforced layer embedded in a polymer matrix; and securing a reinforcement element, preferably an elongated reinforcement element, to a face of the laminate structure along an edge portion of the wind turbine blade part.

[0017] Similarly and more specifically, according to a seventh aspect, there is provided a method of manufacturing a shear web of a wind turbine blade, wherein the wind turbine blade extends in a longitudinal direction parallel to a longitudinal axis and having a tip end and a root end, wherein the shear web is configured to be arranged between a pressure side shell part and a suction side shell part of the wind turbine blade such that it extends substantially in the longitudinal direction between a tip end surface facing the tip end and a root end surface facing the root end. The method comprises: forming the shear web with a laminate structure comprising at least a first fibre- reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, forming a recess in at least one of the tip end surface and the root end surface, and securing a reinforcement element, preferably an elongated reinforcement element, along the recess to the laminate structure of the shear web.

[0018] Likewise, and also more specifically, according to a eighth aspect, there is provided a method of manufacturing a wind turbine blade shell part for a wind turbine blade for a horizontal axis wind turbine, wherein the wind turbine blade extends in a longitudinal direction parallel to a longitudinal axis and having a tip end and a root end. The method comprises the steps of: forming the wind turbine blade shell part with a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, such that the laminate structure comprises a first glue surface, which is configured to be adhered to a second glue surface of a second wind turbine shell part, and securing a reinforcement element, preferably an elongated reinforcement element, to the first glue surface such that it extends along an edge portion of the wind turbine blade shell part.

[0019] It is seen that the first to eighth aspects all provide improvements in relation to the cracks forming in or propagating into the laminate structure of the wind turbine blade part. This relates both to the described methods and the products obtained.

[0020] In the following, various embodiments are described that are applicable to any of the above- mentioned aspects. The embodiments can be combined with each other.

[0021] According to a preferred embodiment, the reinforcement element is a rope-shaped element comprising a bundle of second reinforcement fibres. In other words, the rope-shaped element is formed as a rope. This also means that the rope-shaped element is an elongated element and can be draped to follow the edge of the wind turbine blade part to reinforce the edge and prevent crack from forming or propagating into the laminate structure of the wind turbine blade part or into a joint at the edge of the wind turbine blade part. In the following, the terms "rope-shaped element" and "rope" are used interchangeably. It should also be clear that the invention may comprise a plurality of such reinforcement elements, e.g. two parallelly arranged reinforcement elements.

[0022] The rope-shaped element preferably comprises a bundle of unidirectionally arranged second reinforcement fibres, or equivalently that the second reinforcement fibres are unidirectionally arranged. Thus, the unidirectionally arranged fibres help to reinforce the edge of the wind turbine blade part and effectively prevent the formation or propagation of cracks in the laminate structure or joint at the edge. The unidirectionally arranged fibres may be substantially parallel to each other, or they may be twisted. However, the unidirectionally arranged fibres must generally be aligned in the longitudinal direction of the rope-shaped element.

[0023] According to preferred embodiments, a diameter of the reinforcement element is at least 5 mm or more preferably at least 8 mm, or even more preferably at least 10 mm. Further, the diameter may be at most 20 mm, or preferably at most 16 mm. As preferred examples, the diameter of the reinforcement element may be 5-20 mm, more preferably 10-16 mm. Accordingly, it is seen that the rope is different from fibre rovings that are found in fibre-reinforcement mats. The rope may advantageously be a 12 mm diameter UD (unidirectional).

[0024] According to a preferred embodiment, the second reinforcement fibres are glass fibres. The individual fibre may for instance have a diameter of 3-20 pirn. Accordingly, it is clear that there is a significant number, i.e. several thousands, of fibres in the rope-shaped element.

[0025] The first fibres are preferably glass fibres, carbon fibres or a combination thereof. It may also be possible to use aramid fibres, nylon fibres, or any other suitable fibres for reinforcing a wind turbine blade part.

[0026] According to a particularly preferable embodiment, as already explained above, the reinforcement element is arranged to prevent the formation of crack and / or prevent cracks from propagating. This can be formation at the laminate structure or going into the laminate structure, or alternatively or in addition to this into a joint at the edge of the wind turbine blade part. In another preferred embodiment, the reinforcement element is secured to the laminate structure via a layer of glass fabric infused with resin, the layer of glass fabric being arranged between the laminate structure and the reinforcement element. This provides an excellent bonding to the laminate structure and further ensures that cracks do not form. As a preferred design, the glass fabric may be a chopped fibre strand material (CSM).

[0027] In yet another preferred embodiment, the reinforcement element is secured to the laminate structure via an over-lamination layer, e.g. a biax layer. This aids in keeping the reinforcement element, i.e. the rope, in place as well as a smooth transition to the laminate structure of the wind turbine blade part. The securing can be achieved by a full coverage or partial coverage along the length of the reinforcement element.

[0028] In a further preferred embodiment, one of the layers is removed from the laminate structure at the position, where the reinforcement element is added due to the fact that the cover layer negatively impacts peel at the bond line. By removing a layer, the number of layers remain substantially constant at the reinforcement element and on either side of the reinforcement element.

[0029] In a preferred embodiment, the reinforcement element is provided with a chamfer at either a first end or a second end thereof. The chamfer may advantageously have an angle of 20-70 degrees, preferably an angle of 30-60 degrees, more preferably an angle of 40-50 degrees, e.g. around 45 degrees. By having a chamfer at one or both ends of the reinforcement element, or rope, there is provided a stiffness transition to the laminate structure of the wind turbine part. Thus, any discontinuities in stiffness are minimised.

[0030] As already recited above, the first wind turbine blade part may be a shear web, which is arranged between a pressure side shell part and a suction side shell part of the wind turbine blade and extends substantially in the longitudinal direction between a tip end surface facing the tip end and a root end surface facing the root end, wherein the shear web comprises a recess formed in at least one of the tip end surface and the root end surface, and wherein the reinforcement element is secured along the recess. The recess extends in a flapwise direction between the pressure side shell part and a suction side shell part. The recess is concave as seen from the end surface at which it is formed. The recess ensures that there is a stiffness transition in the spanwise direction of the shear web at the end of the shear web between the shear web and the spar caps or blade shell. The recess may advantageously be formed as an elliptical, semi-circular, or parabolic contour (or cutout). These shapes provide optimum stiffness transitions. However, the thin laminates that are needed at the very end of the shear web and along the edge of the end are prone to formation of cracks due to stress concentrations at the end. The use of ropes for reinforcing the edge greatly alleviates this potential problem.

[0031] The shear web may comprise a shear web body and a web flange, preferably two web flanges, wherein at least the shear web body comprises a sandwich construction with a core material sandwiched between fibre reinforcement layers comprising the at least first fibre-reinforced layer. The shear web flange or flanges are used for adhering to the inner surfaces of the blade shell parts or spars, whereas the shear web body extends between the web flanges. The core material is preferably made of at least one of a polymer material, preferably a foamed polymer material, and a wooden material, preferably balsawood. The shear web body and flanges may advantageously be formed as an I-shaped or C-shaped shear web.

[0032] As already indicated above, the recess may be formed in the shear web body and thus extend between the two web flanges. In use, the recess in the shear web body extends in the flapwise direction of the web. The recess may advantageously extend substantially between the pressure side shell and the suction side shell of the wind turbine blade.

[0033] In a preferred embodiment, the core material is provided with a chamfer at the recess. The sandwich construction is thus tapered and becomes thinner towards the position where the reinforcement element (the rope-shaped reinforcement element) is positioned. Accordingly, the core material may be chamfered such that the thickness of the core material decreases towards the recess, and such that only one or more fibre-reinforcement layers are located in an area proximal to the recess. Thereby, a stiffness transition is provided, and further the reinforcement element is arranged in an area, where only fibre layers are present in the laminate. Accordingly, it is also clear that the reinforcement element is secured to the area proximal to the recess. The chamfer angle of the chamfer of the core material may have an angle in the range 5-20 degrees, preferably in the range 10-16 degrees, e.g. around 14 degrees.

[0034] As further explained above, the first wind turbine blade part may be a first wind turbine blade shell part, which comprises a first glue surface, which is adhered to a second glue surface of a second wind turbine shell part, wherein the reinforcement element is secured to the first glue surface. Thus, the reinforcement element is arranged to be located in a glue joint between the first glue surface of the wind turbine blade shell part and the second glue surface of the second wind turbine blade shell part. Accordingly, the reinforcement element is arranged to stop cracks from propagating in the glue joint. Further, the reinforcement element may also prevent cracks from forming in or propagating into the laminate structure of the wind turbine blade shell part. The second glue surface of the second shell part may also have reinforcement elements secured to it.

[0035] It should of course be noted that the wind turbine blade may comprise both shell parts and shear webs and that the reinforcement elements, or ropes, may be secured to both the shell parts and the shear web.

[0036] According to a preferred embodiment, a plurality of reinforcement elements is secured to the first glue surface. Thus, if a crack should propagate past one reinforcement element or initiate from an intermediate position, one of the additional reinforcement elements may effectively prevent the crack from propagating in the glue joint.

[0037] According to another preferred embodiment, the wind turbine blade shell part is an upwind shell part (or pressure side shell part) and the second wind turbine blade shell part is a downwind shell part (or suction side shell part). The upwind shell part and the downwind shell part may be adhered to each other at a leading edge of the wind turbine blade and at a trailing edge of the wind turbine blade. Accordingly, it is also clear that the first glue surface and second glue surface are located at either the leading edge or the trailing edge of the blade. It is also clear that the shell parts may be adhered to each other via additional glue surfaces at the other of the leading edge or the trailing edge of the blade, and further that these additional glue surfaces may also be provided with reinforcement elements secured to said surfaces.

[0038] In a preferred embodiment, the reinforcement element is secured to the face of the laminate structure by wetting the reinforcement element with a resin and curing the resin. This provides an efficient method of securing the reinforcement element to the laminate structure. The reinforcement element may for instance be co-cured with the laminate structure of the wind turbine blade part. Alternatively, it may be connected to the laminate structure after manufacture of the wind turbine blade part. Accordingly, according to another preferred embodiment, the wind turbine blade part is premanufactured, and the reinforcement element is secured to the face of the laminate structure by retrofitting. In accordance with another embodiment, the reinforcement element is secured to the laminate layer (74) by covering the reinforcement element with an over-lamination layer, e.g. a biax layer (i.e. a layer with biaxially arranged reinforcement fibres). The over-lamination layer may be infused or pre-wetted with a resin to secure the reinforcement element to the face of the laminate structure. The over-lamination may for instance be made of a glass fibre material, e.g. a material with biaxially arranged glass fibres.

[0039] According to a preferred embodiment, any of the methods comprises grinding a zone on the laminate structure and applying a securing layer of fibre material, such as a chopped fibre strand mat (CSM), over the zone grinded on the laminate structure. The reinforcement element may for instance be wetted with a resin and is secured on the securing layer of fibre material applied over the zone grinded on the laminate structure.

[0040] DETAILED DESCRIPTION OF THE INVENTION

[0041] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0042] Fig. 1 shows a wind turbine,

[0043] Fig. 2 shows a schematic view of a wind turbine blade,

[0044] Fig. 3 shows a schematic view of an airfoil profile of the wind turbine blade,

[0045] Fig. 4 shows a schematic view of the wind turbine blade, seen from above and from the side,

[0046] Figs. 5a-5c illustrate exemplary schematic views of shear webs of a wind turbine blade,

[0047] Fig. 6 shows a schematic view of a cross-section of a wind turbine blade,

[0048] Fig. 7 is a schematic side view of a shear web according to the present invention,

[0049] Fig. 8 is a schematic top view of shear webs that extend along substantially the entire spar caps of a wind turbine blade,

[0050] Fig. 9 is a schematic top view of shear webs that are segmented in the spanwise direction of the wind turbine blade,

[0051] Fig. 10 is a perspective view of an arrangement of shear webs and spar caps,

[0052] Fig. 11 shows a schematic view of a wind turbine blade with blade shell parts adhered to each other, Fig. 12 shows a schematic view of another example of a glue joint between two wind turbine blade shell parts,

[0053] Fig. 13 shows a schematic view of a glue joint provided with reinforcement elements, Fig. 14 illustrates the function of the reinforcement elements in a glue joint, Fig. 15 shows a schematic top view of a first example of a glue joint,

[0054] Fig. 16 shows a schematic top view of a second example of a glue joint, and

[0055] Fig. 17 illustrates steps involved in a method of manufacturing a wind turbine blade part.

[0056] It will be understood that elements common to the different embodiments of the invention have been provided with the same reference numerals in the drawings.

[0057] 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 furthest from the hub 8, the blade extending in a spanwise direction between the root 16 and the tip 14. The rotor has a radius denoted R.

[0058] 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 30 closest to the hub, a profiled or an airfoil region 34 furthest away from the hub and a transition region 32 between the root region 30 and the airfoil region 34. 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. An array of trailing edge serrations is provided along a portion of the trailing edge 20 of the blade. In general, flow of air over the wind turbine blade 10 extends from the leading edge 18 to the trailing edge 20 in a generally transverse or chordwise direction.

[0059] The airfoil region 34 (also called the profiled region) has an ideal or almost ideal blade shape with respect to generating lift, whereas the root region 30 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 30 is typically constant along the entire root area 30. The transition region 32 has a transitional profile 42 gradually changing from the circular or elliptical shape 40 of the root region 30 to the airfoil profile 50 of the airfoil region 34. The chord length of the transition region 32 typically increases substantially linearly with increasing distance / -from the hub.

[0060] The airfoil region 34 has an airfoil profile 50 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 / ■from the hub.

[0061] It should be noted that the chords of different sections of the blade normally do not lie in a common plane, since the blade may be twisted and / or curved (i.e. pre-bent), thus providing the chord plane with a correspondingly twisted and / or curved course, this being most often the case in order to compensate for the local velocity of the blade being dependent on the radius from the hub.

[0062] The wind turbine blade 10 comprises a shell body 45, which is made of a fibre-reinforced polymer material, e.g. a polymer matrix reinforced with glass fibres and / or carbon fibres and is further, as shown in Fig. 2b, provided with a ring-shaped root end flange 55 connected to a root end face 17 of the shell body 45. As shown in Fig. 2a, the shell body 45 is often made of an upwind blade shell part 24 (or pressure side shell part) and a downwind blade shell part 26 (or suction side shell part), which are bonded to each other near the leading edge 18 along a first bond line 28 and the trailing edge 20 of the blade 10 along a second bond line 29. Wind turbine blades are generally formed from fibre-reinforced plastics material, e.g. glass fibres and / or carbon fibres which are arranged in a mould and cured with a resin to form a solid structure. Modern wind turbine blades can often be more than 50 metres, and even more than 100 metres, in length, having blade root diameters of several metres. Wind turbine blades are generally designed for relatively long lifetimes and to withstand considerable structural and dynamic loading.

[0063] Fig. 3 shows a schematic view of an airfoil profile 50 of a typical blade of a wind turbine depicted with the various parameters, which are typically used to define the geometrical shape of an airfoil. The airfoil profile 50 has a pressure side 52 and a suction side 54, which during use - i.e. during rotation of the rotor - normally face towards the windward (or upwind) side and the leeward (or downwind) side, respectively. The airfoil 50 has a chord 60 with a chord length c extending between a leading edge 56 and a trailing edge 58 of the blade. The airfoil 50 has a thickness t, which is defined as the distance between the pressure side 52 and the suction side 54. The thickness t of the airfoil varies along the chord 60. The deviation from a symmetrical profile is given by a camber line 62, which is a median line through the airfoil profile 50. The median line can be found by drawing inscribed circles from the leading edge 56 to the trailing edge 58. The median line follows the centres of these inscribed circles and the deviation or distance from the chord 60 is called the camber f. The asymmetry can also be defined by use of parameters called the upper camber (or suction side camber) and lower camber (or pressure side camber), which are defined as the distances from the chord 60 and the suction side 54 and pressure side 52, respectively.

[0064] Airfoil profiles are often characterised by the following parameters: the chord length c, the maximum camber f, the position <7 / of the maximum camber f, the maximum airfoil thickness t, which is the largest diameter of the inscribed circles along the median camber line 62, the position dt of the maximum thickness t, and a nose radius (not shown). These parameters are typically defined as ratios to the chord length c. Thus, a local relative blade thickness ( / c is given as the ratio between the local maximum thickness (and the local chord length c. Further, the position dPof the maximum pressure side camber may be used as a design parameter, and of course also the position of the maximum suction side camber.

[0065] Fig. 4 shows some other geometric parameters of the blade. The blade has a total blade length L. As shown in Fig. 2, the root end is located at position r= 0, and the tip end is located at r= L. The shoulder 48 of the blade is located at a position r = Ln, and has a shoulder width W, which equals the chord length at the shoulder 48. The diameter of the root is defined as D. Further, the blade is provided with a pre-bend, which is defined as Ay, which corresponds to the out-of-plane deflection from a pitch axis 22 of the blade.

[0066] Fig. 6 shows a schematic view of a cross section of the blade along the line I-I shown in Fig. 2. As previously mentioned, the blade 10 comprises a pressure side shell part 24 and a suction side shell part 26. The pressure side shell part 24 comprises a spar cap 62, also called a main laminate, which constitutes a load bearing part of the pressure side shell part 24. The spar cap 62 comprises a plurality of fibre layers 63 mainly comprising unidirectional fibres aligned along the longitudinal direction of the blade in order to provide stiffness to the blade. The suction side shell part 38 also comprises a spar cap 64 comprising a plurality of fibre layers 65. The pressure side shell part 24 may also comprise a sandwich core material 69 typically made of balsawood or foamed polymer and sandwiched between a number of fibre-reinforced skin layers. The sandwich core material 69 is used to provide stiffness to the shell in order to ensure that the shell substantially maintains its aerodynamic profile during rotation of the blade. Similarly, the suction side shell part 26 may also comprise a sandwich core material 69'. The spar cap 62 of the pressure side shell part 24 and the spar cap 64 of the suction side shell part 26 are connected via a first shear web 66 and a second shear web 66'. The shear webs 66, 66' are in the shown embodiment shaped as substantially I-shaped webs. The first shear web 60 comprises a shear web body and two web foot flanges. The shear web body comprises a sandwich core material 67, such as balsawood or foamed polymer, covered by a number of skin layers 68 made of a number of fibre layers. The second shear web 66' has a similar design with a shear web body and two web foot flanges, the shear web body comprising a sandwich core material 67' covered by a number of skin layers 68' made of a number of fibre layers. The sandwich core material 67, 67' of the two shear webs 66, 66' may be chamfered near the flanges in order to transfer loads from the webs 66, 66' to the main laminates 62, 64 without the risk of failure and fractures in the joints between the shear web body and web foot flange.

[0067] The blade shells 24, 26 may comprise further fibre-reinforcement at the leading edge and the trailing edge. Typically, the shell parts 24, 26 are bonded to each other via glue flanges. Additionally, very long blades may comprise sectional parts with additional spar caps, which are connected via one or more additional shear webs.

[0068] The invention relates to providing a reinforcement element along an edge of one of the wind turbine blade components to lower the risk of formation of cracks or cracks propagating into a laminate structure of the wind turbine blade part or into a glue joint at the laminate structure of the wind turbine blade parts. The invention generally relates to the individual wind turbine blade components, the finished wind turbine blade, as well as methods of manufacturing said parts or retrofitting the wind turbine blade parts with the reinforcement element. For instance, there is provided a wind turbine blade that comprises: a plurality of wind turbine blade parts that are assembled to form the wind turbine blade, the plurality of wind turbine blade parts comprising a first wind turbine blade part, wherein the first wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the first wind turbine blade part comprises an edge portion, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to a face of the laminate structure of the first wind turbine blade part and extends along the edge portion of the first wind turbine blade part. From the solution, it is clear that the elongated reinforcement element is distinct from the layers and reinforcement fibres of the laminate structure. It is also clear that the reinforcement element is a fibre-based reinforcement structure. Further, it is clear that the reinforcement element is a drapeable reinforcement element that is configured to be draped along the edge of the wind turbine blade part. The reinforcement element is preferably a rope-shaped element comprising a bundle of second reinforcement fibres. In other words, the rope-shaped element is formed as a rope. The reinforcement element is thus also seen to be drapeable, such that it can follow the contour of the blade component at the edge portion. The rope may be co-cured with the wind turbine blade part or retrofitted to the wind turbine blade part. Preferably, the rope is fitted to the wind turbine blade part by wetting the rope with a resin and curing the resin, such that it provides a bond to the surface of the wind turbine blade part.

[0069] In the following, exemplary embodiments are described in relation to a shear web and a blade shell part for a wind turbine blade. However, it is understood that variations are possible, and that the reinforcement element may be arranged at edge portions of other wind turbine blade components. In general, the embodiments may have any of the variations described under the summary of the invention above.

[0070] Referring now to Figs. 5a to 5c in conjunction, which illustrate a shear web structure 70 for a wind turbine blade 10. The shear web structure 70 is part of the load bearing structure of the wind turbine blade 10. The shear web structure 70 beam as well as the aerodynamic shell or shell parts may be manufactured separately. The aerodynamic shell is often manufactured as two shell parts, typically as a pressure side shell part 24 and a suction side shell part 26. The two shell parts i.e., the pressure side shell part 24 and the suction side shell part 26 are glued or otherwise connected to the shear web structure 70 and are further glued to each other along a leading edge and trailing edge of the wind turbine blade 10. The shear web structure 70 may be structured to reinforce the wind turbine blade 10 and prevent excessive bending or buckling to take up at least shear forces. In an embodiment, the shear web structures 70 may be formed from beam members having I- or C- shaped cross-sections, and such shear web structures 70 may include a main body with load-bearing flanges (also referred to as the foot flanges) extending therefrom at opposed ends of the main body. Accordingly, it is also clear that the shear web structures 70 described here may correspond to or be similar to the shear web structures 66, 66' described in relation to Fig. 6.

[0071] The web structure comprises a core 72 that may be positioned between the pressure side shell part 24 and a suction side shell part 26 of the wind turbine blade 10. The core 72 may be made of material such as but not limiting to balsawood or foamed polymer. Other feasible materials for manufacturing the core 72 may be contemplated herein without deviating from the scope of the present disclosure. The core 72 may be defined with recess facing towards the tip end or root end of the wind turbine blade. The recess may for instance have an elliptical contour on at least one of a face facing the trailing edge or a leading edge of the wind turbine blade 10. However, the shape may also be substantially parabolic, semi-circular, hyperbolic, or another suitable shape. In an implementation, a peripheral portion of the core 72 may be defined with a chamfer. The chamfer may be defined on a face of the core 72 facing the tip end or root end of the wind turbine blade 10. An angle of the chamfer on the core 72 ranges from about 10° to about 16°, preferably 14°. Further, the core 72 may be sandwiched between or may be covered by a number of laminate layers 74. The laminate layers 74 may also be referred to as the skin layers 72 and used interchangeably.

[0072] The laminate layers 74 may be made of a number of fibre layers. For instance, the laminate layers 74 may be made of glass fabric including biax fibres infused with resin. The said laminate layers 74 may partially extend outwardly from the core 72 in a direction towards the root end and / or the tip end of the wind turbine blade 10 and may be defined with a complementing elliptical profile. In a preferred embodiment, the laminate layer 74 may be extending outwardly and away from the core 72 in the direction towards the root end of the wind turbine blade 10. That is, the laminate layer 74 may cover the entire core 72 with a portion of the laminate layer 74 forming an overhang towards the root end. The overhang formed by the laminate layer 74 may be defined with the elliptical contour (or other shape) complementing the elliptical contour of the core 72. The overhang or the portion extending outwardly in the direction of at least one of the root end and / or the tip end from the core 72 may be reinforced by a reinforcement element 76.

[0073] The reinforcement element 76 may be a unidirectional rope (also called a UD rope). However, any other feasible reinforcement element 76 may be contemplated herein without deviating from the scope of the present disclosure. The reinforcement element 76 may have shear modulus ranging from about 18 GPa to about 25 GPa. In a preferred embodiment, the shear modulus of the reinforcement element 76 may be about 21 GPa. Further, the diameter of the reinforcement element 76 may range from about 10 mm to about 16 mm. In a preferred embodiment, the diameter of the reinforcement element 76 may be about 12 mm. In an implementation, the reinforcement element 76 may be defined with a chamfer at either end. An angle of the chamfer may range from about 40° to about 50°. In a preferred embodiment, the angle of the chamfer at either end of the reinforcement element 76 may be about 45°. The reinforcement element 76 may be secured to the laminate layer 74 along the elliptical contour (or other shaped contour) and may be positioned proximally to a periphery of the core 72. In an embodiment, the reinforcement element 76 may be secured to the laminate layer 74 on at least one face of the laminate layer 74 facing the leading edge and the trailing edge of the blade 10. In an implementation, a length of the reinforcement element 76 may be substantially identical to a length of the elliptical contour defined on the core 72 as shown in Fig. 5b. In another implementation, the length of the reinforcement element 76 may be greater than the length of the elliptical contour defined on the core 72 and may extend beyond the elliptical contour of the core 72 as shown in Fig. 5a without deviating from the scope of the present disclosure.

[0074] In accordance with an embodiment, the reinforcement element 76 may be wetted with resin and may be disposed along the, e.g. elliptical, contour of the laminate layers 74 to secure the reinforcement element 76 with the laminate layer 74. Further, the reinforcement element 76 disposed along the, e.g. elliptical, contour of the laminate layers 74 is secured firmly by a layer of biax fibre. Also, the said layer of biax fibre may be structured to encase / cover the reinforcement element 76. The biax fibre may be a layer of glass fabric infused with resin. Provision of the reinforcement element 76 about the elliptical contour of the laminate layers 74 may eliminate initiation of cracks on the laminate layers as the reinforcement element 76 suitably strengthens / improves the structural characteristics of the laminate layer 74 about the elliptical contour. In an implementation, the reinforcement element 76 may be retrofitted to the existing web structures of the wind turbine blade 10. In the forthcoming paragraphs, the method of manufacturing the web structure 70 of the wind turbine 10 is described.

[0075] In an embodiment of the present disclosure, a method of manufacturing the web structure 70 is described. The method includes providing the core 72 made of material such as but not limiting to balsawood or foamed polymer between the pressure side shell part 24 and the suction side shell part 26 of the wind turbine blade 10. The core 72 may be then sandwiched between the laminate layers 74 such that the laminate layer 74 covers the whole of the core 72 and a portion of the laminate layer 74 partially extends outwardly from the core 72 in a direction towards at least one of the root end and / or the tip end. The core 72 and the laminate layer 74 may be defined with the complementing elliptical contour on at least one of a face facing the trailing edge or the leading edge of the wind turbine blade 10. Further, the reinforcement element 76 may be secured on at least one of a face of the laminate layer 74 along the elliptical contour and may be positioned substantially proximal to the periphery of the core. In an implementation, the reinforcement material may be secured to or may be applied over the laminate layer 74 and may be covered by a cover ply. The reinforcement member 74 may be disposed on at least one face of the laminate layer 74 facing the leading edge and / or the trailing edge. The cover ply may include a layer of biax fibre and a layer of CSM material. In an implementation, the cover ply may include a layer of biax fibre alone without deviating from the scope of the present disclosure. In an embodiment, the method may include grinding a zone of the laminate layer 74 up to a certain depth before securing the reinforcement element 76. Grinding of the zone of the laminate layer 74 up to the certain depth to accommodate the reinforcement member 76 may eliminate impact on the bond line peel. Further, a layer of CSM (chopped strand mat) material may be applied over the zone grinded on the laminate layer. The reinforcement element 76 wetted with a resin is applied onto the CSM material applied over the zone grinded on the laminate layer. Further, the method includes applying the cover ply over the reinforcement element 76. The cover ply may include a layer of biax fibre and a layer of CSM material. In another implementation, the cover ply may include a layer of biax fibre alone without deviating from the scope of the present disclosure.

[0076] In another implementation, the method of manufacturing the web structure 70 includes providing the core 72 made of material such as but not limiting to balsawood or foamed polymer. The laminate layers 74 may be provided on either sides of the core 72 to sandwich the core 72 therebetween. The core 72 maybe sandwiched between the laminate layers 74 such that the laminate layer 74 covers the whole of the core 72 and a portion of the laminate layer 74 partially extends outwardly from the core 72 defining the overhang in the direction towards at least one of the root end and / or the tip end. The core 72 and the laminate layer 74 may be defined with the complementing, e.g. elliptical, contour on at least one of a face facing the trailing edge or the leading edge of the wind turbine blade 10. Further, the reinforcement element 76 may be secured on at least one of the face of the laminate layer 74 along the, e.g. elliptical, contour and may be positioned substantially proximal to the periphery of the core 72. The reinforcement element 76 may be wetted with resin and may be disposed on the at least one face of the laminate layers 74. Further, the method includes applying the cover ply over the reinforcement element 76. The cover ply may include a layer of biax fibre and a layer of CSM material. In another implementation, the cover ply may include a layer of biax fibre alone without deviating from the scope of the present disclosure. The web structure 70 manufactured using the described method may then be disposed between the pressure side shell part 24 and the suction side shell part 26 of the wind turbine blade 10. The shear web structure 70 of the present disclosure efficiently reinforces the, e.g. elliptical, contour of the shear web structure 70 without effecting bond line loads. Also, the configuration of the shear web structure 70 with the reinforcement element 76 eliminates crack initiation at the, e.g. elliptical, contour. The configuration of the shear web structure 70 according to the embodiments of the present disclosure may be retrofittable into existing wind turbine blades.

[0077] Fig. 7 is a schematic side view of a shear web 70 showing the shear web body. The shear web 70 has a side surface 75 extending between an upper edge 77, a lower edge 78, a first end surface 71 and a second end surface 73. When arranged within a blade shell body, the first end surface 71 will typically face towards the root end of the blade, while the second end surface 73 will typically face towards the tip end of the blade.

[0078] The shear web 70 of Fig. 4 comprises a recess at its end surface 71 facing towards the root end of the blade and a recess at its end surface 73 facing towards the tip end of the blade. Both recesses have a parabolic, elliptical, semi-circular or hyperbolic shape which is defined by a base section and opposing tip sections, each tapering towards the end of the shear web. Fig. 7 also illustrates the length L, or spanwise extent, of the shear web, as well as the height Hl at the first end 71 and the height H2 at the second end 73 of the shear web. It is noted that the shear web 70 for instance may extend along substantially the entire length of the spar caps of wind turbine blade, as shown in Fig. 8. However, the shear web 70 may also be segmented into individual segments 70a-70d, e.g. as shown in Fig. 9.

[0079] Fig. 10 is a perspective view of an arrangement of shear webs 70a-70d. The shear webs 70a-d are arranged between spar caps 79a, 79b, which are provided along the respective pressure and suction side shell members (not shown in the previous figures). The arrangement corresponds to that shown in the top view in Fig. 9. It is clear that the arrangement shown in Fig. 8 corresponds to a similar design with shear webs arranging along substantially the entire extent of the spar caps.

[0080] As seen from Figs. 7-10, each shear web 70 or segmented shear web 70a-70d may have a recess formed in one or both ends of the shear web 70 or segmented shear web 70a-70d. Further, it is clear that the edges along the recess may be provided with a reinforcement element 76 as shown in Fig. 5a-5c. In the following, with reference to Figs. 11-16, exemplary embodiments are described in utilising reinforcement elements in glue joints to prevent cracks from propagating in the glue joint or propagating into the parts that are joined at the glue joint. In particular, the examples are related to glue joints for adhering blade shell parts to each other.

[0081] Fig. 11 shows a simple schematic view of a wind turbine blade with a pressure side shell part 24 adhered to a suction side shell part 26 along a first glue joint 80 at a leading edge of the wind turbine blade and along a second glue joint 82 at a trailing edge of the wind turbine blade. Thus, the two shell parts are at each joint adhered to each other via a first glue surface on one of the blade shell parts and a second glue surface on the other one of the blade shell parts.

[0082] In principle, it is sufficient to have the first glue joint 80 directly between the two shell parts 24, 26 at the leading edge as shown in Fig. 11. However, it is also possible to have a glue joint flange 86 extend from one of the two blade shell parts 24, 26, such to form a glue joint 84 with an inner glue surface of one or both of the blade shell parts as shown in Fig. 12.

[0083] In the following, the invention is explained in relation to any of the glue joints 80, 82, 84 described above. For each of the examples, the wind turbine blade shell parts each comprise a laminate structure at a glue surface, and one or more reinforcement elements are secured to at least one of the glue surfaces that are used for the glue joint. It is further seen that the glue surfaces are located along edges of the blade shell part.

[0084] Fig. 13 shows a schematic view of a glue joint provided with reinforcement elements 76. The glue joint is formed between the pressure side shell part 24 and the suction side shell part. In the shown embodiment, a plurality of reinforcement elements 76 are formed as elongated elements with unidirectionally arranged fibres, preferably glass fibres. The reinforcement elements are preferably formed as ropes. Fig. 14 illustrates the function of the reinforcement elements 76 in a glue joint. The formation of a crack in the glue joint is illustrated, and it seen that it propagates within the glue joint until it encounters one of the reinforcement elements 76, which effectively prevents the crack from propagating further in the glue joint or into the laminate structures of one of the wind turbine blade shell parts 24, 26.

[0085] Fig. 15 and 16 show schematic top views of different examples of arranging a plurality of reinforcement elements 76 or ropes in a glue joint. In the example shown in Fig. 15, the reinforcements 76 are arranged along the glue joint substantially in the spanwise direction of the wind turbine blade. In principle, it is also possible to arrange the reinforcement elements 76 in a transverse direction. However, for manufacturing purposes, it is simpler to arrange them in the spanwise direction. In the example shown in Fig. 16, the reinforcement elements are arranged diagonally. For example, reinforcement elements 76 on one of the glue surfaces of the glue joint may be arranged parallel to each other in a first angle (e.g. approximately 30 or 45 degrees relative to a spanwise direction), whereas reinforcement elements 76 on the other of the glue surfaces of the glue joint may be arranged parallel to each other in a second angle (e.g. approximately -30 or - 45 degrees relative to a spanwise direction).

[0086] The disclosure also relates to the manufacture of any of the aforementioned wind turbine blade components and the final wind turbine blade as well as a method of retrofitting a reinforcement element along an edge of a wind turbine blade component. The methods are generally aligned around the steps shown in Fig. 17. The method 100 involves in a first step 110 providing a layup including laying up layers including at least a first fibre-reinforced layer to form a laminate structure. In a second step 120, the laminate structure is infused with a resin. In a third step 130, the resin is cured to form the wind turbine blade part including the laminate structure with the at least first fibre- reinforced layer embedded in a polymer matrix. In a fourth step 140, a reinforcement element, preferably an elongated reinforcement element, is secured to a face of the laminate structure along an edge portion of the wind turbine blade part. It is recognised that the reinforcement element may be co-infused and cured with the laminate structure, or that it can be secured in a subsequent step. It is also recognised that the method may involve removing one or more layers, e.g. by grinding, at the position of securing the reinforcement element prior to securing the reinforcement element as described in the summary of the invention above. It is also recognised that an overlamination layer may be used to securing the reinforcement element to the laminate structure.

[0087] Exemplary embodiments

[0088] Exemplary embodiments of the present disclosure are set out in the following items and clauses:

[0089] Items

[0090] 1. A wind turbine blade (10) for a horizontal axis wind turbine (2), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16), and wherein the wind turbine blade (10) comprises: a plurality of wind turbine blade parts that are assembled to form the wind turbine blade, the plurality of wind turbine blade parts comprising a first wind turbine blade part, wherein the first wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the first wind turbine blade part comprises an edge portion, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to a face of the laminate structure of the first wind turbine blade part and extends along the edge portion of the first wind turbine blade part.

[0091] 2. A wind turbine blade according to item 1, wherein the reinforcement element is a rope-shaped element comprising a bundle of second reinforcement fibres.

[0092] 3. A wind turbine blade according to item 2, wherein the rope-shaped element comprises a bundle of unidirectionally arranged second reinforcement fibres.

[0093] 4. A wind turbine blade according to any of the preceding items, wherein a diameter of the reinforcement element is 5-20 mm, preferably 10-16 mm.

[0094] 5. A wind turbine blade according to any of items 2-4, wherein the second reinforcement fibres are glass fibres.

[0095] 6. A wind turbine blade according to any of the preceding items, wherein the reinforcement element is arranged to prevent the formation of crack and / or prevent cracks from propagating.

[0096] 7. A wind turbine blade according to any of the preceding items, wherein the reinforcement element is secured to the laminate structure via a layer of glass fabric infused with resin, the layer of glass fabric being arranged between the laminate structure and the reinforcement element.

[0097] 8. A wind turbine blade according to item 7, wherein the glass fabric is a chopped fibre strand material.

[0098] 9. A wind turbine blade according to any of the preceding items, wherein the reinforcement element is secured to the laminate structure via an over-lamination layer, e.g. a biax layer.

[0099] 10. A wind turbine blade according to any of the preceding items, wherein the reinforcement element is provided with a chamfer at either a first end or a second end thereof. 11. A wind turbine blade according to item 10, wherein the chamfer has an angle of 20-70 degrees, preferably an angle of 30-60 degrees, more preferably an angle of 40-50 degrees, e.g. around 45 degrees.

[0100] 12. A wind turbine blade according to any of the preceding items, wherein the first wind turbine blade part is a shear web, which is arranged between a pressure side shell part and a suction side shell part of the wind turbine blade and extends substantially in the longitudinal direction between a tip end surface facing the tip end and a root end surface facing the root end, wherein the shear web comprises a recess formed in at least one of the tip end surface and the root end surface, and wherein the reinforcement element is secured along the recess.

[0101] 13. A wind turbine blade according to item 12, wherein the recess is formed as an elliptical, semicircular, or parabolic contour.

[0102] 14. A wind turbine blade according to any of items 12-13, wherein the shear web comprises a shear web body and a web flange, wherein at least the shear web body comprises a sandwich construction with a core material sandwiched between fibre reinforcement layers comprising the at least first fibre-reinforced layer.

[0103] 15. A wind turbine blade according to item 14, wherein the recess is formed in the shear web body.

[0104] 16. A wind turbine blade according to any of items 14-15, wherein the core material is provided with a chamfer at the recess.

[0105] 17. A wind turbine blade according to item 16, wherein the core material is chamfered such that the thickness of the core material decreases towards the recess, and such that only one or more fibre-reinforcement layers are located in an area proximal to the recess.

[0106] 18. A wind turbine blade according to item 17, wherein the reinforcement element is secured to the area proximal to the recess. 19. A wind turbine blade according to any of items 16-18, wherein a chamfer angle of the chamfer of the core material has an angle in the range 5-20 degrees, preferably in the range 10-16 degrees, e.g. around 14 degrees.

[0107] 20. A wind turbine blade according to any of items 1-11, wherein the first wind turbine blade part is a first wind turbine blade shell part, which comprises a first glue surface, which is adhered to a second glue surface of a second wind turbine shell part, and wherein the reinforcement element is secured to the first glue surface.

[0108] 21. A wind turbine blade according to item 20, wherein a plurality of reinforcement elements is secured to the first glue surface.

[0109] 22. A wind turbine blade according to any of items 20-21, wherein the wind turbine blade shell part is an upwind shell part and the second wind turbine blade shell part is a downwind shell part.

[0110] 23. A wind turbine blade according to any of items 20-22, wherein the upwind shell part and the downwind shell part are adhered to each other at a leading edge of the wind turbine blade and at a trailing edge of the wind turbine blade.

[0111] 24. A wind turbine blade part for a wind turbine blade (10) for a horizontal axis wind turbine (2), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16), wherein the wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the first wind turbine blade part comprises an edge portion, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to a face of the laminate structure of the first wind turbine blade part and extends along the edge portion of the wind turbine blade part.

[0112] 25. A wind turbine blade part according to item 24, wherein the reinforcement element is a ropeshaped element comprising a bundle of second reinforcement fibres. 26. A wind turbine blade part according to any of items 24-25, wherein the blade shell part comprises any of the features recited in any of items 3-23, or any combination of the features recited in any of items 3-23.

[0113] 27. A shear web for a wind turbine blade for a horizontal axis wind turbine (2), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16), wherein the shear web extends between a tip end surface and a root end surface and is configured to be arranged between a pressure side shell part and a suction side shell part of the wind turbine blade such that it extends substantially in the longitudinal direction between a tip end surface facing the tip end and a root end surface facing the root end, wherein the shear web comprises a recess formed in at least one of the tip end surface and the root end surface, and wherein a reinforcement element, preferably an elongated reinforcement element, is secured along the recess to a laminate structure of the shear web.

[0114] 28. A shear web according to item 27, wherein the reinforcement element is a rope-shaped element comprising a bundle of second reinforcement fibres.

[0115] 29. A shear web according to any of items 27-28, wherein the shear web comprises any of the features recited in any of items 3-11 or items 13-19, or any combination of the features recited in any of items 3-11 or items 13-19.

[0116] 30. A wind turbine blade shell part for a wind turbine blade for a horizontal axis wind turbine (2), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16), wherein the wind turbine blade shell part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the laminate structure of the wind turbine blade shell part comprises a first glue surface, which is configured to be adhered to a second glue surface of a second wind turbine shell part, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to the first glue surface and extends along the edge portion of the wind turbine blade shell part. 31. A wind turbine blade shell part according to item 30, wherein the reinforcement element is a rope-shaped element comprising a bundle of second reinforcement fibres.

[0117] 32. A wind turbine blade shell part according to any of items 30-31, wherein the shear web comprises any of the features recited in any of items 3-11 or items 21-23, or any combination of the features recited in any of 3-11 or items 21-23.

[0118] 33. A method of fitting or retrofitting a wind turbine blade part with a reinforcement structure, wherein the method comprises the steps of: providing a wind turbine blade part for a wind turbine blade (10) for a horizontal axis wind turbine (2), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16), wherein the wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the first wind turbine blade part comprises an edge portion, securing a reinforcement element, preferably an elongated reinforcement element, to a face of the laminate structure of the first wind turbine blade part such that it extends along an edge portion of the wind turbine blade part.

[0119] 34. A method according to item 33, wherein the reinforcement element is a rope-shaped element comprising a bundle of second reinforcement fibres.

[0120] 35. A method according to any of items 33-34, wherein the reinforcement element is secured to the face of the laminate structure by wetting the reinforcement element with a resin and curing the resin.

[0121] 36. A method according to any of items 33-35, wherein the reinforcement element is co-cured with the laminate structure of the wind turbine blade part.

[0122] 37. A method according to any of items 33-36, wherein the wind turbine blade part is premanufactured, and the reinforcement element is secured to the face of the laminate structure by retrofitting. 1

[0123] 38. A method according to any of items 33-37, wherein the reinforcement element (76) is secured to the laminate layer (74) by covering the reinforcement element with an over-lamination layer, e.g. a biax layer.

[0124] 39. A method according to any of items 33-38, which comprises grinding a zone on the laminate structure and applying a securing layer of fibre material, such as a chopped fibre mat, over the zone grinded on the laminate structure.

[0125] 40. A method according to any of items 33-39, wherein the reinforcement element (76) is wetted with a resin and is secured on the securing layer of fibre material applied over the zone grinded on the laminate structure.

[0126] 41. A method of manufacturing a wind turbine blade part, wherein the method comprises the steps of: providing a layup including laying up layers including at least a first fibre-reinforced layer to form a laminate structure; infusing the laminate structure with a resin; curing the resin to form the wind turbine blade part including the laminate structure with the at least first fibre-reinforced layer embedded in a polymer matrix; and securing a reinforcement element, preferably an elongated reinforcement element, to a face of the laminate structure along an edge portion of the wind turbine blade part.

[0127] 42. A method according to item 41, wherein the reinforcement element is a rope-shaped element comprising a bundle of second reinforcement fibres.

[0128] 43. A method according to any of items 41-42, wherein the reinforcement element is co-cured with the laminate structure.

[0129] 44. A method according to any of items 41-43, wherein the reinforcement element is secured to the laminate structure after the step of curing.

[0130] 45. A method according to any of items 41-44, wherein the method involves any of the steps described in any of items 35-40. 46. A method of manufacturing a shear web of a wind turbine blade (10), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16), wherein the shear web is configured to be arranged between a pressure side shell part and a suction side shell part of the wind turbine blade such that it extends substantially in the longitudinal direction between a tip end surface facing the tip end and a root end surface facing the root end, wherein the method comprises the steps of: forming the shear web with a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, forming a recess in at least one of the tip end surface and the root end surface, and securing a reinforcement element, preferably an elongated reinforcement element, along the recess to the laminate structure of the shear web.

[0131] 47. A method according to item 46, wherein the reinforcement element is a rope-shaped element comprising a bundle of second reinforcement fibres.

[0132] 48. A method according to any of items 46-47, wherein the shear web comprises a shear web body and a web flange, wherein at least the shear web body comprises a sandwich construction with a core material sandwiched between fibre reinforcement layers comprising the at least first fibre-reinforced layer.

[0133] 49. A method according to item 48, wherein the recess is formed in the shear web body.

[0134] 50. A method according to any of items 45-49, wherein the core material is provided with a chamfer at the recess.

[0135] 51. A method according to any of items 45-50, wherein the core material is chamfered such that the thickness of the core material decreases towards the recess, and such that only one or more fibre-reinforcement layers are located in an area proximal to the recess.

[0136] 52. A method according to any of items 45-51, wherein the reinforcement element is secured to the area proximal to the recess. 53. A method according to any of items 45-52, wherein a chamfer angle of the chamfer of the core material has an angle in the range 5-20 degrees, preferably in the range 10-16 degrees, e.g. around 14 degrees.

[0137] 54. A method according to any of items 45-53, wherein the recess is formed as an elliptical, semicircular, or parabolic contour.

[0138] 55. A method according to to any of items 45-54, wherein the reinforcement element (76) is secured to the laminate layer (74) through and covered by a layer of biax fibre.

[0139] 56. A method according to any of items 45-55, which comprises grinding a zone on the laminate layer (74) and applying a layer of CSM material over the zone grinded on the laminate layer (74).

[0140] 57. A method according to any of items 45-56, wherein the reinforcement element (76) is wetted with a resin and is secured on the CSM material applied over the zone grinded on the laminate layer (74).

[0141] 58. A method according to any of items 45-57, which comprises applying a layer of biax fibre including a glass fabric infused with resin on the reinforcement element (76).

[0142] 59. A method of manufacturing a wind turbine blade shell part for a wind turbine blade for a horizontal axis wind turbine (2), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16), wherein the method comprises the steps of: forming the wind turbine blade shell part with a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, such that the laminate structure comprises a first glue surface, which is configured to be adhered to a second glue surface of a second wind turbine shell part, and securing a reinforcement element, preferably an elongated reinforcement element, to the first glue surface such that it extends along an edge portion of the wind turbine blade shell part.

[0143] 60. A method according to item 59, wherein the reinforcement element is a rope-shaped element comprising a bundle of second reinforcement fibres. 61. A method according to any of items 59-60, wherein the method involves any of the steps described in any of items 35-40.

[0144] 62. A wind turbine blade part for a wind turbine blade for a horizontal axis wind turbine (2), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16), wherein the wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the laminate structure of the wind turbine blade part comprises a first glue surface, which is configured to be adhered to a second glue surface of a second wind turbine part, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to the first glue surface and extends along the edge portion of the wind turbine blade shell part.

[0145] 63. A wind turbine blade part according to item 62, wherein the wind turbine blade part comprises any of the features recited in items 1-32.

[0146] Clauses

[0147] Original claim set (clauses with multiple dependencies)

[0148] 1. A web structure (70) of a wind turbine blade (10), the web structure (70) comprising: a core (72) configured to be positioned between a pressure side shell part (24) and a suction side shell part (26) of the wind turbine blade (10) of the wind turbine blade (10); a laminate layer (74) structured to be received on either sides of the core (72) and sandwich the core (72) therebetween, the laminate layer (74) extends partially outwardly from the core (72) in a direction towards at least one of a root end and / or a tip end of the wind turbine blade (10) and being defined with an elliptical contour on at least one of a face facing a trailing edge or a leading edge of the wind turbine blade (10); and a reinforcement element (76) secured to at least one of a face of the laminate layer (74) along the elliptical contour and proximal to a periphery of the core (72).

[0149] 2. The web structure (70) according to clause 1, wherein the reinforcement element (76) is a unidirectional rope. 3. The web structure (70) according to any of clauses 1-2, wherein a diameter of the reinforcement element (76) ranges from about 10 mm to about 16 mm.

[0150] 4. The web structure (70) according to any of clauses 1-3, wherein the reinforcement element (76) is secured to the laminate layer (74) through and covered by a layer of biax fibre.

[0151] 5. The web structure (70) according to any of clauses 1-4, wherein the reinforcement element (76) is secured to the laminate layer (74) through a layer of a glass fabric infused with resin.

[0152] 6. The web structure (70) according to any of clauses 1-5, wherein the reinforcement element (76) is defined with a chamfer at either ends and an angle of chamfer ranges from about 40° to about 50°, preferably 45°.

[0153] 7. The web structure (70) according to any of clauses 1-6, wherein the core (72) is defined with a chamfer about the periphery and the chamfer angle ranges from about 10° to about 16°, preferably 14°.

[0154] 8. A method of manufacturing a web structure (70) of a wind turbine blade (10), the method comprising: providing a core (72) of the web structure (70) between a pressure side shell part (24) and a suction side shell part (26) of the wind turbine blade (10); providing a laminate layer (74) on either sides of the core (72), wherein the laminate layer (74) is structured to sandwich the core (72) therebetween, the laminate layer (74) extends partially outwardly from the core (72) in a direction towards at least one of a root end and / or a tip end of the wind turbine blade (10) and being defined with an elliptical contour on at least one of a face facing a trailing edge or a leading edge of the wind turbine blade (10); securing a reinforcement element (76) on at least one of a face of the laminate layer (74) along the elliptical contour and proximal to a periphery of the core (72).

[0155] 9. The method according to clause 8, wherein the reinforcement element (76) is secured to the laminate layer (74) through and covered by a layer of biax fibre.

[0156] 10. The method according to any of clauses 8-9, which comprises grinding a zone on the laminate layer (74) and applying a layer of CSM material over the zone grinded on the laminate layer (74). 11. The method according to any of clauses 8-10, wherein the reinforcement element (76) is wetted with a resin and is secured on the CSM material applied over the zone grinded on the laminate layer (74).

[0157] 12. The method according to any of clauses 8-11, which comprises applying a layer of biax fibre including a glass fabric infused with resin on the reinforcement element (76). List of reference numerals

Claims

CLAIMS1. A wind turbine blade (10) for a horizontal axis wind turbine (2), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16), and wherein the wind turbine blade (10) comprises: a plurality of wind turbine blade parts that are assembled to form the wind turbine blade, the plurality of wind turbine blade parts comprising a first wind turbine blade part, wherein the first wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the first wind turbine blade part comprises an edge portion, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to a face of the laminate structure of the first wind turbine blade part and extends along the edge portion of the first wind turbine blade part.

2. A wind turbine blade according to claim 1, wherein the reinforcement element is a ropeshaped element comprising a bundle of second reinforcement fibres, e.g. wherein the rope-shaped element comprises a bundle of unidirectionally arranged second reinforcement fibres.

3. A wind turbine blade according to any of the preceding claims, wherein a diameter of the reinforcement element is 5-20 mm, preferably 10-16 mm, and / or wherein the second reinforcement fibres are glass fibres.

4. A wind turbine blade according to any of the preceding claims, wherein the reinforcement element is arranged to prevent the formation of crack and / or prevent cracks from propagating.

5. A wind turbine blade according to any of the preceding claims, wherein the reinforcement element is secured to the laminate structure via a layer of glass fabric infused with resin, the layer of glass fabric being arranged between the laminate structure and the reinforcement element, e.g. wherein the glass fabric is a chopped fibre strand material.

6. A wind turbine blade according to any of the preceding claims, wherein the reinforcement element is secured to the laminate structure via an over-lamination layer, e.g. a biax layer.

7. A wind turbine blade according to any of the preceding claims, wherein the reinforcement element is provided with a chamfer at either a first end or a second end thereof, e.g. wherein the chamfer has an angle of 20-70 degrees, preferably an angle of 30-60 degrees, more preferably an angle of 40-50 degrees, e.g. around 45 degrees.

8. A wind turbine blade according to any of the preceding claims, wherein the first wind turbine blade part is a shear web, which is arranged between a pressure side shell part and a suction side shell part of the wind turbine blade and extends substantially in the longitudinal direction between a tip end surface facing the tip end and a root end surface facing the root end, wherein the shear web comprises a recess formed in at least one of the tip end surface and the root end surface, and wherein the reinforcement element is secured along the recess.

9. A wind turbine blade according to claim 8, wherein the recess is formed as an elliptical, semicircular, or parabolic contour, e.g. wherein the shear web comprises a shear web body and a web flange, wherein at least the shear web body comprises a sandwich construction with a core material sandwiched between fibre reinforcement layers comprising the at least first fibre-reinforced layer, and optionally wherein the recess is formed in the shear web body.

10. A wind turbine blade according to any of claims 8-9, wherein the core material is provided with a chamfer at the recess, e.g. wherein the core material is chamfered such that the thickness of the core material decreases towards the recess, and such that only one or more fibre-reinforcement layers are located in an area proximal to the recess, optionally wherein the reinforcement element is secured to the area proximal to the recess.

11. A wind turbine blade according to claim 10, wherein a chamfer angle of the chamfer of the core material has an angle in the range 5-20 degrees, preferably in the range 10-16 degrees, e.g. around 14 degrees.

12. A wind turbine blade according to any of claims 1-7, wherein the first wind turbine blade part is a first wind turbine blade shell part, which comprises a first glue surface, which is adhered to a second glue surface of a second wind turbine shell part, and wherein the reinforcement element is secured to the first glue surface.

13. A wind turbine blade according to claim 12, wherein a plurality of reinforcement elements is secured to the first glue surface.

14. A wind turbine blade according to any of claims 12-13, wherein the wind turbine blade shell part is an upwind shell part and the second wind turbine blade shell part is a downwind shell part, e.g. wherein the upwind shell part and the downwind shell part are adhered to each other at a leading edge of the wind turbine blade and at a trailing edge of the wind turbine blade.

15. A wind turbine blade part for a wind turbine blade (10) for a horizontal axis wind turbine (2), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16), wherein the wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the first wind turbine blade part comprises an edge portion, wherein a reinforcement element, preferably an elongated reinforcement element, is secured to a face of the laminate structure of the first wind turbine blade part and extends along the edge portion of the wind turbine blade part.

16. A method of fitting or retrofitting a wind turbine blade part with a reinforcement structure, wherein the method comprises the steps of: providing a wind turbine blade part for a wind turbine blade (10) for a horizontal axis wind turbine (2), wherein the wind turbine blade (10) extends in a longitudinal direction parallel to a longitudinal axis and having a tip end (14) and a root end (16), wherein the wind turbine blade part comprises a laminate structure comprising at least a first fibre-reinforced layer comprising first reinforcement fibres embedded in a polymer matrix, and wherein the first wind turbine blade part comprises an edge portion,securing a reinforcement element, preferably an elongated reinforcement element, to a face of the laminate structure of the first wind turbine blade part such that it extends along an edge portion of the wind turbine blade part.

17. A method of manufacturing a wind turbine blade part, wherein the method comprises the steps of: providing a layup including laying up layers including at least a first fibre-reinforced layer to form a laminate structure; infusing the laminate structure with a resin; curing the resin to form the wind turbine blade part including the laminate structure with the at least first fibre-reinforced layer embedded in a polymer matrix; and securing a reinforcement element, preferably an elongated reinforcement element, to a face of the laminate structure along an edge portion of the wind turbine blade part.

18. A method according to any of claims 16-17, wherein the reinforcement element is a ropeshaped element comprising a bundle of second reinforcement fibres, e.g. wherein the rope-shaped element comprises a bundle of unidirectionally arranged second reinforcement fibres.

19. A method according to any of claims 16-18, wherein the reinforcement element is co-cured with the laminate structure of the wind turbine blade part.

20. A method according to any of claims 16-19, wherein the reinforcement element is secured to the laminate structure after the step of curing, e.g. wherein the reinforcement element is secured to the face of the laminate structure by wetting the reinforcement element with a resin and curing the resin.