CN117813448A

CN117813448A - Shear web for wind turbine blades and method of making same

Info

Publication number: CN117813448A
Application number: CN202280055730.4A
Authority: CN
Inventors: S·兰德尔; J·海特
Original assignee: Vestas Wind Systems AS
Current assignee: Vestas Wind Systems AS
Priority date: 2021-06-16
Filing date: 2022-05-20
Publication date: 2024-04-02

Abstract

A shear web (44) for a wind turbine blade (20) includes a lower flange (46), an upper flange (48), and a shear web (44) extending between the lower flange (46) and the upper flange (48). A web structure (50), wherein at least one of the lower flange (46), the upper flange (48) and the web structure (50) includes an open lattice structure (60, 62, 71, 94, 100), the The open lattice structure has multiple elongated fiber composite shafts (64, 66, 68, 70, 72, 74, 96, 98) intersecting at multiple nodes of the structure. Also disclosed is a method of fabricating a shear web (44) using continuous fiber reinforced additive manufacturing methods.

Description

Shear web for wind turbine blade and method of making the same

Technical Field

The present invention relates generally to wind turbines, and more particularly to a shear web for a wind turbine blade having improved strength-weight characteristics. The invention also relates to an improved method of manufacturing a shear web which provides greater design flexibility, which in turn provides improved load distribution and allows the shear web to be more directly adapted to the expected load conditions on the blade during use.

Background

Wind turbine generators are used to produce electrical energy using renewable resources without burning fossil fuels. The wind turbine generator converts kinetic energy from wind into electrical energy and includes a tower, a nacelle mounted atop the tower, a rotor hub rotatably supported by the nacelle, and a plurality of rotor blades attached to the hub. The hub is coupled with a generator housed inside the nacelle. Thus, when wind forces the blades to rotate, the generator produces electrical energy. In recent years wind energy has become a more attractive alternative energy source and the number of wind turbines, wind farms etc. has increased significantly both on land and at sea. Moreover, the size of wind turbines has also increased significantly, with modern wind turbine blades extending between 50 meters and 100 meters in length or more, while in the future the length of wind turbine blades is expected to increase still further.

Modern wind turbine blades have a construction that generally includes a shell and a spar structure located inside the shell. The casing provides an aerodynamic aspect of the blade and includes a profile configured to generate lift from oncoming wind, ultimately rotating the blade. The outer shell typically has a laminated composite construction of a plurality of fibrous layers, one or more core materials embedded within the fibrous layers, and a resin matrix, and includes a windward half shell and a leeward half shell bonded together at the leading and trailing edges of the blade. The beam structure of the interior of the blade provides the load carrying aspect of the blade. In one known arrangement, the spar structure includes a pair of spar caps and one or more shear webs extending therebetween. The spar caps may be arranged in opposing relationship across the height of the blade, with one spar cap being associated with the windward half shell and the other spar cap being associated with the leeward half shell. Liang Gaike to be integrated into the housing such that the beam cover forms part of the housing. Instead, liang Gaike to adhesively adhere to the inner surface of the housing. The spar caps extend longitudinally along a majority of the length of the wind turbine blade, while in one arrangement Liang Gaike is formed from a stack of pultruded carbon fibre reinforced plastic strips.

The shear web is connected between the spar caps and includes a central web and first and second flanges disposed at first and second ends of the central web, respectively. The shear web is thus substantially I-shaped in cross-section and bridges the gap between the windward and leeward sides of the outer shell. The flanges are oriented transversely to the intermediate web when viewed in cross-section and provide a means for mounting the shear web between opposed spar caps. In this regard, the flanges are configured to be bonded to the spar caps with an adhesive. In one known arrangement, the first and second flanges may be formed from a T-shaped pultruded moulding of carbon fibre reinforced plastic and include a foot and a upstand (upstand), wherein the foot forms the flange, the upstand facilitating connection of the foot to the intermediate web. The intermediate web typically has a laminated composite construction consisting of a plurality of fibrous layers, one or more core materials embedded within the fibrous layers, and a resin matrix. Depending on the size of the blade and the expected loads, the spar structure may include more than one shear web extending between opposing spar caps.

The housing is typically made by a molding process using a windward mold half and a leeward mold half. In this regard, fibrous layers (such as fiberglass layers and/or carbon fiber layers) and core materials (such as various foam cores and/or wood cores) may be laid in a mold (with a beam cover when such a beam cover is integrated within a shell) and resin is incorporated into the mold in a vacuum-assisted resin transfer molding process (VARTM). The half-shells are then cured in the corresponding mold halves. Shear webs, and in particular at least their central webs, are also typically made by a moulding process using separate mould tools. In a similar manner, the fibrous layers, core material and T-shaped pultrusions may be laid in a mold tool, with resin being incorporated into the mold during the vacuum assisted resin transfer molding process. The shear web is then cured within the mould. To form the blade, a shear web may be positioned within one of the blade mold halves and one of the flanges of the shear web may be adhesively bonded to the spar caps associated with the respective half shells. The other half shell (which does not have a shear web) may then be juxtaposed with respect to the mold half comprising the shear web. The shell may be adhesively bonded along the leading and trailing edges of the blade, while the other flange of the shear web may be adhesively bonded to the spar cap associated with the other half of the shell.

Although the above-described wind turbine blades and methods of manufacturing wind turbine blades have proven successful, wind turbine blade manufacturers are continually seeking improved designs and manufacturing methods, particularly as the size of wind turbine blades is expected to increase. In this regard, current manufacturing processes have inherent limitations on the design improvements of wind turbine blades. For example, current molding processes rely primarily on laminated composite constructions (e.g., fiber layers, core materials, and resins) to make the shells and shear webs of wind turbine blades. Thus, the manufacturing process itself results in certain design constraints that limit the ability of manufacturers to improve the performance of wind turbine blades.

Furthermore, current molding processes for wind turbine blades lack flexibility, which further limits wind turbine blade design. From a scale perspective, the time and capital investment for producing the windward and leeward halves, and the associated fixtures and equipment for handling the halves (e.g., for flipping the other half of the mold relative to one half) is very high. This slow time scale and significant capital investment inherent in mold manufacturing not only increases the overall cost of providing a product (such as a wind turbine or wind turbine blade), but also limits the ability of manufacturers to make changes to the blade design over the product lifecycle (i.e., the casting mold cannot be easily or cost effectively altered to accommodate the design changes). Thus, manufacturers must fully address a certain blade design over a longer period of time in order to obtain a reasonable return in that investment. The inherent aspect of the molding process, and the inability to make changes over the product lifecycle, often requires that the blade be over-constrained in its design. More specifically, instead of detailed local design configurations such as shells or shear webs based on (anticipated) local loading conditions on the blade, a more comprehensive design configuration is used that satisfies worst-case loading constraints for critical areas of the blade. Thus, a large portion of the blade includes design configurations where the anticipated load constraints in these sections of the blade are excessive. This represents not only an unnecessary increase in the cost of materials (such as fibers, resin and core materials), but also an unnecessary increase in the total weight of the shear web and blade.

Furthermore, loads exerted on the outer shell of the wind turbine blade during use are eventually transferred to the root end of the blade via the internal beam structure. However, most of the load transfer between the shell and the spar structure occurs in a relatively small region of the flanges centered on the shear web (e.g., an I-shaped shear web), while the outboard portion of the flanges away from the shear web is only subjected to a small portion of the load. This can lead to poor load distribution and high peak loads in the adhesive bond between the flange of the shear web and the spar cap.

In view of this, manufacturers seek an improved method for fabricating wind turbine blades (including a method of fabricating a shear web for a wind turbine blade) that overcomes the limitations of current molding processes. Manufacturers are also seeking an improved wind turbine blade component (including a relatively high strength, relatively lightweight shear web) that can provide detailed local design configurations based on anticipated load conditions and improved load distribution in the bond area between the shear web and spar caps.

Disclosure of Invention

A shear web for a wind turbine blade is disclosed that addresses the above-described deficiencies. The shear web includes a lower flange, an upper flange, and a web structure extending between the lower flange and the upper flange. At least one of the lower flange, upper flange and web structure includes an open lattice structure having a plurality of elongated fiber composite axes (composite axes, composite spindle) intersecting each other at a plurality of junctions of the open lattice structure. The open lattice structure associated with the shear web may be formed by a continuous fiber reinforced additive manufacturing process. The open lattice structure provides wind turbine blade components with significantly improved strength-weight properties and generally cannot be formed using conventional molding techniques used in wind turbine blade manufacture. Furthermore, the additive manufacturing process for the blade component provides greater design flexibility and adaptability to the blade design that is not achievable in current manufacturing processes.

In one embodiment, the web structure comprises a three-dimensional open lattice structure extending between a lower flange and an upper flange, wherein a plurality of elongated fiber composite axes extend in three dimensions. The arrangement of the fiber composite axes may be unstructured, i.e. without an observable pattern or ordered building blocks forming an open lattice structure. Alternatively, the arrangement of axes may be structured, with identifiable patterns or building blocks forming an open lattice structure. For example, in one embodiment, the axes may be organized into a plurality of panels (i.e., the panels are building blocks of an open lattice structure). More specifically, in an exemplary embodiment, the web structure may include a plurality of first open lattice panels and a plurality of second open lattice panels, wherein the plurality of first panels intersect the plurality of second panels at a plurality of junctions to define a three-dimensional open lattice structure. In an exemplary embodiment, the plurality of first panels and the plurality of second panels may be arranged substantially perpendicular to each other.

In one embodiment, each of the plurality of first panels defines a first direction of extension and may include a plurality of axes (e.g., staggered axes) that are disposed generally non-perpendicular to the first direction of extension in a crisscrossed manner. Further, each of the plurality of first panels may include an axis (e.g., a normal axis) disposed generally perpendicular to the first direction of extension. The distribution of the shafts may be non-uniform in the first direction of extension and based on the load conditions of the shear web. For example, the distribution of both normal and staggered axes may be non-uniform in the first direction of extension and may be based on the load conditions of the shear web. More specifically, in the first direction of extension, the density of the axes (e.g., staggered axes and/or normal axes) in the high load region of the shear web may be greater than the density of the axes in the low load region of the shear web.

Further in this embodiment, each of the plurality of second panels defines a second direction of extension and includes a plurality of axes (e.g., staggered axes) that are disposed in a crisscrossed manner generally non-perpendicular to the second direction of extension. In addition, each of the plurality of second panels may further include a plurality of axes (e.g., normal axes) disposed generally perpendicular to the second direction of extension. The distribution of the axes in each of the plurality of second panels may be substantially uniform in the second direction of extension and may for example be based on providing a more uniform load across the shear web. More specifically, in the second direction of extension, the density of the axes may be substantially uniform.

In one embodiment, the plurality of second panels may be unevenly distributed in the first extension direction and may be based on, for example, the load conditions of the shear web. More specifically, in the first direction of extension, the density of the second panel in the high load region of the shear web may be greater than the density of the second panel in the low load region of the shear web.

In another embodiment, at least one of the bottom flange and the top flange includes an open lattice panel oriented to extend in the first direction of extension. In this embodiment, the open lattice panel forming at least one of the lower flange and the upper flange includes a plurality of axes (e.g., staggered axes and/or normal axes) arranged relative to the first direction of extension. The distribution of the central axes of the panel may be non-uniform in the first direction of extension and based on the load conditions of the shear web. More specifically, in the first direction of extension, the density of the axes in the high load region of the shear web may be greater than the density of the axes in the low load region of the shear web.

In another embodiment, the ends of the lower and upper flanges of the shear web configured to be adjacent to the root end of the wind turbine blade may include extension tabs (tabs). In one embodiment, the extension sheet may include a widened portion configured to increase the bond surface area of the shear web. Further, in the transition region adjacent the ends of the shear web, the axles extending from the lower and upper flanges may have a swept (swept) or scalloped (scaled) configuration. These features of the end of the shear web at the root end of the blade are configured to reduce the peel load (peel load) between the shear web and the shell of the wind turbine blade.

In another aspect of the invention, the shear web may have a hybrid configuration, with some aspects of the shear web having a conventional configuration and other aspects of the shear web having an open lattice configuration formed by a continuous fiber-reinforced additive manufacturing process. For example, in one embodiment, the web structure may have a laminated composite construction (laminated composite construction), the lower flange and the upper flange may have a laminated composite construction or a pultruded construction, and an open lattice structure may be formed on at least one surface of the lower flange, the upper flange, and the web structure. In an exemplary embodiment, the web structure may include opposing first and second surfaces, and an open lattice structure may be formed on each surface of the web structure. In another embodiment, each of the lower flange and the upper flange may include an outer surface, and an open lattice structure may be formed on the outer surface of each of the lower flange and the upper flange.

In another embodiment, a wind turbine blade having the shear web described above is disclosed. In one embodiment, a wind turbine blade may have a segmented blade design and include a first blade section and a second blade section configured to join at a connection interface. The first and second blade sections include first and second shear web portions, respectively, wherein at least web structures of the first and second shear web portions are configured to be connected to one another in a nested relationship when the first and second blade sections are joined together. The arrangement of the fibre composite axes in the web structure of the first shear web portion and the arrangement of the axes in the web structure of the second shear web portion are such that the axes of the shear webs are substantially aligned at the connection interface when the blade sections are joined. This arrangement provides a continuous line of force between the lower flange and the upper flange at the connection joint. A wind turbine having the wind turbine blade described above is also disclosed.

In yet another embodiment, a method of making a shear web for a wind turbine blade is disclosed. The method comprises the following steps: providing a lower flange; providing an upper flange; providing a web structure configured to extend between a lower flange and an upper flange; forming at least one of a lower flange, an upper flange, and a web structure in an open lattice structure having a plurality of elongated fiber composite axes intersecting each other at a plurality of junctions of the open lattice structure; connecting a lower flange to a lower end of the web structure; and connecting the upper flange to the upper end of the web structure. The open lattice structure is formed by a continuous fiber reinforced additive manufacturing process.

In one embodiment, the forming step further includes forming the web structure as a three-dimensional open lattice structure having a plurality of fibrous elongate composite axes extending in three-dimensional space. For example, in an exemplary embodiment, forming the web structure as a three-dimensional open lattice structure further includes: forming a plurality of first open lattice panels; forming a plurality of second open lattice panels; orienting a plurality of first open cell panels; and orienting the plurality of second open lattice panels such that the plurality of first panels intersect the plurality of second panels at a plurality of junctions to define a three-dimensional open lattice structure.

In one embodiment, forming the plurality of first panels may further include, for each of the plurality of first panels, forming a plurality of axes (e.g., staggered axes) that are arranged in a crisscrossed manner generally non-perpendicular to the first direction of extension. The method may further include, for each of the plurality of first panels, forming a plurality of axes (e.g., normal axes) disposed generally perpendicular to the first direction of extension. In an exemplary embodiment, the method may include non-uniformly distributing the shaft in the first extension direction, for example, based on load conditions of the shear web. More specifically, the method may include providing an axial density in a first extension direction in a high load region of the shear web that is greater than an axial density in a low load region of the shear web.

In another embodiment, forming the plurality of second panels may further include, for each of the plurality of second panels, forming a plurality of axes (e.g., staggered axes) that are arranged in a crisscrossed manner generally non-perpendicular to the second direction of extension. The method may further include, for each of the plurality of second panels, forming a plurality of axes (e.g., normal axes) disposed generally perpendicular to the first direction of extension. In an exemplary embodiment, the method may include substantially uniformly distributing the shaft in the second direction of extension to more uniformly distribute the force, for example, on the shear web. More specifically, the method may include providing an axial density in the second extension direction in the high load region of the shear web that is greater than an axial density in the low load region of the shear web.

In another embodiment, the method may include substantially uniformly distributing the plurality of first panels in the second direction of extension. More specifically, the method may include providing a substantially uniform density of the plurality of first panels in the second direction of extension.

In another embodiment, providing the bottom and top flanges may further comprise, for each flange, forming an open lattice panel and orienting the panel in a first direction of extension, wherein the open lattice panel forming the bottom and top flanges is formed by a continuous fiber reinforced additive manufacturing process.

In one embodiment, forming the panels for the lower and upper flanges may further include, for each of the panels, forming a plurality of axes (e.g., staggered axes and/or normal axes) relative to the first direction of extension. In one embodiment, the method includes non-uniformly distributing the shaft in the first extension direction, for example, based on load conditions of the shear web. More specifically, the method may include providing an axial density in a first extension direction in a high load region of the shear web that is greater than an axial density in a low load region of the shear web.

In another embodiment, providing the bottom flange and the top flange further includes forming an extension piece on each of the bottom flange and the top flange. In one embodiment, forming the extension piece includes forming the extension piece with a widened portion to increase the adhesive surface area. In another embodiment, the method may include arranging shafts extending from the lower flange and the upper flange in a fanned configuration adjacent to ends of the lower flange and the upper flange including extension pieces.

In yet another embodiment, the method may include forming the lower flange and the upper flange from a laminated composite construction or a pultruded construction; forming a web structure from the laminated composite construction; and forming an open lattice structure on at least one surface of the lower flange, the upper flange, and the web structure.

For example, in one embodiment, the method may include forming an open lattice structure on opposing first and second surfaces of the web structure. Alternatively or additionally, the method may include forming an open lattice structure on an outer surface of each of the lower flange and the upper flange.

In yet another embodiment, a method of making a wind turbine blade includes: forming a first blade half; forming a second blade half; forming a shear web according to the above method; connecting a shear web to the first blade half; connecting the second blade half to the first blade half; and connecting the shear web to the second blade half. The connection of the shear web to the first and second blade halves and the interconnection of the first and second blade halves may be performed simultaneously or may be performed in multiple steps.

In one embodiment, the first and second blade halves may further comprise molding each of the first and second blade halves. Additionally, the method may include forming the wind turbine blade as a first blade section and a second blade section configured to join at a connection interface. The first and second blade sections include first and second shear web portions, respectively, with at least web structures of the first and second shear web portions configured to be connected to one another in a nested relationship. The method further includes connecting the first blade section and the second blade section together at a connection interface such that the arrangement of the shafts in the web structure of the first shear web portion and the arrangement of the shafts in the web structure of the second shear web portion are substantially aligned at the connection interface.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description of the invention given above, and the detailed description given below, serve to explain the invention.

FIG. 1 is a front perspective view of a wind turbine having wind turbine blades according to an embodiment of the present invention;

FIG. 2 is a perspective view of the wind turbine blade of FIG. 1;

FIG. 3 is a cross-sectional view of the wind turbine blade of FIG. 2 illustrating a spar structure in accordance with an embodiment of the present invention;

FIG. 4 is a partial perspective view of the shear web shown in FIG. 3 according to an embodiment of the invention;

FIG. 5 is a schematic characteristic load condition of a web structure of a shear web in a spanwise (span) direction of a blade;

FIG. 6 is a side plan view of the web structure of a wind turbine blade illustrating the axis of the spanwise panel of the web structure;

FIG. 7 is a schematic density distribution of the normal axis of the web structure in the spanwise direction based on expected load conditions;

FIG. 8 is a schematic density distribution in the spanwise direction of the staggered axes of the web structure based on anticipated loading conditions;

FIG. 9 is a schematic characteristic load condition of a web structure of a shear web in a chordwise (chord) direction;

FIG. 10 is a schematic density distribution of alternating axes of web structure in the chordwise direction;

FIG. 11 is a schematic density distribution of the normal axis of the web structure in the chordwise direction;

FIG. 12 is a schematic density distribution in the spanwise direction of a chord-wise panel of a web structure based on expected loading conditions;

FIG. 13A is a front plan view of a chord-wise panel of a low load region of a web structure;

FIG. 13B is a front plan view of a chord-wise panel of the high load area of the web structure;

FIG. 14 is a schematic density distribution of staggered axes in a chordwise panel as a function of spanwise position based on expected load conditions;

FIG. 15 is a cross-sectional view of a shear web having a plurality of spanwise panels according to another embodiment of the invention;

FIG. 16 is another exemplary characteristic load condition of the web structure of the shear web in the chord-wise direction of the blade;

FIG. 17 is a perspective view of a shear web with flanges according to an embodiment of the invention;

FIG. 18 illustrates attachment of the flange of FIG. 17 to a surface by adhesive bonding;

FIG. 19 is a cross-sectional view of a shear web for a wind turbine blade according to another embodiment of the invention;

FIG. 20 is a side plan view of a shear web configuration adjacent a root end of a wind turbine blade;

FIG. 21A illustrates the attachment of the shear web shown in FIG. 20 to a root end section of a wind turbine blade according to one embodiment of the invention;

FIG. 21B illustrates the attachment of the shear web shown in FIG. 20 to a root end section of a wind turbine blade in accordance with another embodiment of the invention;

FIG. 22 illustrates the connection of a shear web to a connection joint of a segmented wind turbine blade; and

FIG. 23 illustrates the alignment of the axes of the web structure of a shear web according to an embodiment of the invention.

Detailed Description

Referring to FIG. 1, a wind turbine 10 includes a tower 12, a nacelle 14 disposed at a top of tower 12, and a rotor 16, with rotor 16 being operatively coupled to a generator (not shown) housed inside nacelle 14. In addition to the generator, nacelle 14 houses the various components required to convert wind energy into electrical energy, as well as the various components required to operate, control, and optimize the performance of wind turbine 10. The tower 12 supports the loads presented by the nacelle 14, rotor 16, and other components of the wind turbine 10 housed inside the nacelle 14, and also operates to elevate the nacelle 14 and rotor 16 to a height above ground level or sea level (as the case may be) at which a less turbulent, fast moving air stream is typically found.

The rotor 16 of the wind turbine 10, denoted horizontal axis wind turbine, is used as the motive force for the electromechanical system. Wind forces exceeding a minimum level will activate the rotor 16 and result in rotation in a plane substantially perpendicular to the wind direction. The rotor 16 of the wind turbine 10 includes a central hub 18 and at least one blade 20, the at least one blade 20 extending outwardly from the central hub 18 at a location circumferentially distributed therearound. In the exemplary embodiment, rotor 16 includes three blades 20, but the number may vary. The blades 20 are configured to interact with the passing air flow to generate lift that rotates the central hub 18 about a longitudinal axis.

Wind turbines 10 may be included in a series of similar wind turbines belonging to a wind farm or wind park that serves as a power plant connected by transmission lines to a power grid, such as a three-phase Alternating Current (AC) grid. The power grid is typically made up of a power plant, a transmission loop and a substation network coupled with a transmission line network that delivers power to loads in the form of end users and other customers of the power company. As is well known to those of ordinary skill in the art, electrical energy is normally supplied from a generator to a power grid.

Wind turbine blades 20 may generally have an improved design and, in one exemplary embodiment, may be configured as an elongated structure having an outer airfoil shell 22 disposed about an inner support element or spar structure 24 disposed inside the shell 22. The shell 22 may be optimally formed to impart desired aerodynamic characteristics to the blade 20 to generate lift, while the beam structure 24 is configured to provide structural aspects (e.g., strength, stiffness, etc.) to the blade 20. The elongate blade 20 includes a root end 26 (the root end 26 being configured to be coupled to the central hub 18 when mounted to the rotor 16), and a tip end 28 longitudinally opposite the root end 26. In the orientation shown in fig. 2, the housing 22 may include a windward half shell 30 defining the underside of the blade 20 and a leeward half shell 32 defining the upper side of the blade 20. The windward half shell 30 and the leeward half shell 32 are coupled together along a leading edge 34 and a trailing edge 36, the leading edge 34 and trailing edge 36 being positioned opposite across the chord line of the blade 20.

As best shown in FIG. 3, to increase strength and rigidity, blade 20 may include a beam structure 24, with beam structure 24 extending longitudinally along at least a portion of the length of blade 20 between a root end 26 and a tip end 28. For example, the beam structure 24 may extend a majority of the length of the wind turbine blade 20 (e.g., greater than 80% or 90% of the length of the blade 20) between the root end 26 and the tip end 28. In the exemplary embodiment, spar structure 24 includes a pair of spar caps 40, 42 associated with respective windward half shells 30 and leeward half shells 32, and a shear web 44 extending between opposing spar caps 40, 42. The spar caps 40, 42 are typically designed to carry bending loads on the blade 20, while the shear web 44 is typically designed to carry shear loads on the blade 20. In one embodiment, spar caps 40, 42 may be integrated within windward half shell 30 and leeward half shell 32 such that spar caps 40, 42 form a portion of outer airfoil shell 22. For example, fig. 3 illustrates such an arrangement. However, in an alternative embodiment (not shown), the beam caps 40, 42 may be separate elements adhesively bonded to the inner surface of the housing 22. In one embodiment, the spar caps 40, 42 may be formed from a stack of pultruded fiber-reinforced composite strips. However, in an alternative embodiment, the spar caps 40, 42 may have a laminated composite construction consisting of multiple fiber layers, resin, and possibly core material.

Shear web 44 extends across the height of blade 20 from windward half shell 30 to leeward half shell 32 and between spar caps 40 and 42. In the exemplary embodiment, shear web 44 includes a lower flange 46, an upper flange 48, and an intermediate web structure 50 extending between lower flange 46 and upper flange 48. As shown in FIG. 3, the lower and upper flanges 46 and 48 of the shear web 44 are configured to be adhesively bonded to the inner surfaces of the spar caps 40 and 42, respectively. For example, in the embodiment shown in FIG. 3, lower flange 46 and upper flange 48 may have a laminated composite construction comprised of a plurality of fibrous layers, resin, and possibly core material that are in turn adhesively bonded to web structure 50. As described in greater detail below, aspects of the present invention are primarily directed to details of the intermediate web structure 50 of the shear web 44. Other aspects of the invention are directed to details of the flanges 46, 48 of the shear web 44. Each aspect will be described in detail below.

In this regard, aspects of the present invention are directed to an intermediate web structure having a three-dimensional open lattice configuration comprised of fiber composite materials. The three-dimensional open lattice construction comprises a plurality of elongate structural members made of fibrous composite material extending in three-dimensional space and intersecting one another to form a network of interconnected rod-like shafts that together form a web structure. Thus, for a given volume of web structure (e.g. 1m ³ ) The fibrous composite will occupy some portion of the volume, while the remaining volume portion will be voids. Thus, the web structure according to aspects of the invention does not have a solid body construction as in the molded web structure of conventional shear webs, but rather comprises a lattice arrangement with void spaces. The concept embodied by the three-dimensional open lattice construction is that the load carrying capacity of the web structure can be significantly increased, such as by the arrangement of the shafts in three-dimensional space, while minimizing the overall weight of the web structure by having comparable (plentiful) void spaces. In other words, the three-dimensional open lattice construction of the web structure provides a strength to weight ratio that exceeds, in many cases far exceeds, the strength to weight ratio of the solid composite web structure produced by the conventional molding process described above. This is important as the size of wind turbine blades continues to grow.

The three-dimensional open lattice configuration of the web structure may not only provide increased strength with lighter weight, but may also provide increased design flexibility through the local arrangement of the shaft based on estimated local load conditions on the web structure (and wind turbine blades). Thus, by the arrangement of the shafts (i.e. the elongate members made of fibre composite material), the web structure may be configured to have a high strength in localized areas subjected to high load conditions and a reduced strength in localized areas subjected to low load conditions. Generally, this approach eliminates the low definition, more comprehensive approach in conventional molding operations, and instead provides a more customized, more elaborate approach to providing material and weight where strength is desired and to reduce material and weight where strength is not desired. In other words, in the intended high load region, the web structure may include a greater number of shafts per unit volume (and thus also a greater mass per unit volume), while in the intended low load region, the web structure may include fewer shafts per unit volume. The axial distribution (and thus the intensity distribution) of the web structure can be characterized by the concept of density, i.e. the amount of fibrous composite mass per unit volume of the axis of the web structure.

In addition to the above, the three-dimensional open lattice configuration of the web structure allows the shear web to be designed in the following manner: providing a more uniform load distribution on the flanges of the shear web and on the bonding area between the flanges and the spar caps. In addition, due to the more uniform load distribution, peak loads on the flanges and bonded areas may be reduced, thereby reducing the likelihood of failure of the bonded joint. As the size of wind turbine blades continues to grow, the ability to strengthen the bond area and reduce peak loads is also important.

To achieve the three-dimensional open lattice configuration of the web structure, and the benefits that it provides for wind turbine blade fabrication, conventional molding processes are partially or entirely abandoned, while employing more adaptive Additive Manufacturing (AM) processes (such as 3-D printing techniques). In many industrial applications, additive manufacturing processes using polymer-based resins are used to produce prototype parts at an early stage of product development, rather than functional parts. This limitation is mainly based on the fact that parts formed from polymer-based resins lack the necessary mechanical properties required for functional components in field conditions. Recently, to improve the mechanical properties of parts made by additive manufacturing, fiber bundles (e.g., staple fibers) have been introduced into the resin matrix inside or just outside the printhead of a 3-D printer, and then printed together to form the part. While the introduction of staple fibers into the matrix increases the strength of the 3-D printed part, it is believed that the strength of such composite parts is lower than conventional mold-based fiber reinforced composites. Accordingly, continuous fiber reinforced additive manufacturing methods have been developed in order to further increase the mechanical properties of 3-D printed parts.

Continuous fiber reinforced additive manufacturing methods integrate continuous fibers with a resin matrix during 3-D printing and may take a variety of forms including in situ impregnation, tow coextrusion, tow extrusion, in situ coagulation (in-situ consolidation), inline impregnation (inline impregnation), and other possible forms. The essence of these methods is to mix the continuous fiber or groups of continuous fibers with a resin matrix in or just outside the printhead of a 3-D printer, and then dispense the fibers and matrix out of the printhead to form the part. The inclusion of continuous fibers in the resin matrix may increase the mechanical properties (e.g., strength) of the composite part so that the 3-D printed part may now operate as a functional part during use. Systems providing continuous fiber reinforced additive manufacturing are commercially available. By way of example and not limitation, continuous Composites company of idad alaren, washington, mu Jier dio, ingersoll Machine Tools company of rocaford, il, markforged company of watton, ma, moi components company of milan, and Orbital Composites company of san jose, ca all provide commercially available continuous fiber additive manufacturing services.

Continuous fiber reinforced additive manufacturing provides free-form geometry generation based on various design criteria such as strength, material and weight considerations, which enables complex and specific custom designs to optimize performance. Furthermore, such additive manufacturing processes provide the ability to change design configurations without the need to modify or replace tools. Thus, the use of a 3-D additive manufacturing process to produce a functional composite structure releases wind turbine designers and manufacturers from the constraints of conventional molding processes. This greatly increases design options for fabricating wind turbine components with improved performance and characteristics, including shear webs for wind turbine blades. Continuous fiber reinforced additive manufacturing methods are known and commercially available. Accordingly, a detailed discussion of such devices and processes will not be described in detail herein. Aspects of the invention are more directed to using these additive manufacturing processes in the production of wind turbine blade components, such as shear webs for wind turbine blades.

One embodiment of the present invention is directed to shear webs, and more particularly to intermediate web structures having a three-dimensional open lattice configuration formed by fiber composite axes extending in three-dimensional space. The three-dimensional nature of the axes may be unstructured, with the axes appearing to be randomly oriented to form a three-dimensional lattice configuration. Alternatively, the three-dimensional nature of the axes may be structured, with identifiable arrangements of axes forming, for example, lattice building blocks. The intermediate web structure may then be formed from an arrangement of interconnected lattice building blocks to provide a three-dimensional open lattice structure. For example, but not limited thereto, the lattice building block may include various polyhedrons or other three-dimensional geometries.

As will be discussed in more detail below, in exemplary embodiments, the three-dimensional open lattice configuration may be formed from a panel arrangement, the panels being formed from fiber composite axes. In other words, the panels are building blocks formed by axes, while the intermediate web structure may be formed by an arrangement of multiple panels to form a three-dimensional open lattice structure (e.g., consider two panels that are not parallel intersecting at an angle to form a three-dimensional open lattice structure). In an exemplary embodiment, the panel may be box-shaped or plate-shaped (e.g., rectangular prism) defining a principal plane generally in a first dimension and a second dimension, and having a reduced extent in a third dimension to provide a plate-like configuration of the panel. For example, one can easily imagine a panel having a length and a height (which define an infinitely thin plane) and a width that is significantly smaller than the length and the height to define a plate-like panel. The fiber composite axes forming the panel extend in the major plane of the panel, but also have an inherent "width" (e.g., the diameter of the axes) that generally defines a reduced third dimension of the panel. Thus, the axis is contained within the volume of the rectangular prism of the panel. The panel is two-dimensional in nature, but since the axis has a "width", the panel does include a small third dimension. In any case, the concept of the panel being planar or defining a plane (account for) has an inherent width of the axis forming the panel. The axes may extend in various directions in the principal plane and intersect one another at junctions to form a lattice panel.

In an exemplary embodiment, for example, the three-dimensional open lattice configuration of the intermediate web structure may be formed from a plurality of panels arranged in a cross-wise fashion. In this regard, selected stacks of panels of a three-dimensional open lattice structure may be interdigitated over a wide range of angles. For example, in one embodiment, the panel pairs may be arranged substantially perpendicular to each other. However, in another embodiment, the pairs of panels may or may not intersect at an angle greater than or less than about ninety degrees, and all of the panels may or may not intersect at the same angle. Thus, it should be understood that the plurality of panels may be arranged in a wide range of configuration(s) to form a three-dimensional open lattice configuration of the intermediate web structure, and should not be limited to those configurations shown and described herein.

FIG. 4 illustrates a shear web 44 according to an exemplary embodiment of the invention. The shear web 44 includes a lower flange 46 and an upper flange 48 and an intermediate web structure 50 produced by a continuous fiber-reinforced additive manufacturing process. Notably, the intermediate web structure 50 has a three-dimensional open lattice configuration formed by fiber composite axes extending in three-dimensional space. Such a construction cannot be achieved by conventional manufacturing techniques, including conventional molding processes. More specifically, web structure 50 includes a plurality of first open cell panels 60 and a plurality of second open cell panels 62 that intersect to form a three-dimensional configuration. Each of the open lattice panels 60 and 62 may be formed of a fiber composite shaft that extends in various directions within a main plane defined by the panels. In one embodiment, and as shown in FIG. 4, the plurality of first panels 60 and the plurality of second panels 62 may be arranged substantially perpendicular to each other (e.g., intersecting at 90+/-5 degrees) to provide a box-like configuration for the web structure 50. However, it should be understood that the open lattice panels 60, 62 may intersect one another at other angles and remain within the scope of this invention.

As shown in fig. 2-4 and 6, wind turbine blade 20 may be described as having a spanwise direction x generally defined by root end 26 and tip end 28 of blade 20 (i.e., extending between root end 26 and tip end 28 of blade 20); a chordwise direction y generally defined by leading edge 34 and trailing edge 36 (i.e., extending between leading edge 34 and trailing edge 36), and a thickness-wise direction z generally defined by windward half shell 30 and leeward half shell 32 (i.e., extending between windward half shell 30 and leeward half shell 32). The lower flange 46 and the upper flange 48 have a plate-like configuration and generally include a main plane extending in the spanwise direction x and the chordwise direction y, and a significantly smaller extension length (extent) in the thickness direction z. Although configured in a plate-like manner, lower flange 46 and upper flange 48 are generally considered to extend along the length of blade 20 in a spanwise direction (referred to as the direction of extension of flanges 46, 48).

The open lattice panels 60, 62 of the intermediate web structure 50 may be arranged with respect to the spanwise, chordwise and thickness directions of the wind turbine blade 20. For example, in an exemplary embodiment, the first panel 60 may be arranged such that the major plane of the panel extends in the spanwise direction and the thickness-wise direction, while the significantly smaller extension length of the panel 60 extends in the chordwise direction (see, e.g., fig. 4 and 6). Accordingly, these open lattice panels 60 may be referred to herein as spanwise panels and may be considered to extend generally along the length of the blade 20 in the spanwise direction (the direction of extension of the panel 60). Further, in the present exemplary embodiment, the second panel 62 may be arranged such that the major plane of the panel extends in the chordwise direction and the thickness direction, while a significantly smaller extension length of the panel 62 extends in the spanwise direction (see, e.g., fig. 3 and 4). Accordingly, these open lattice panels 62 may be referred to herein as chordwise panels, and may be considered to extend generally along the width of the blade 20 in a chordwise direction (the direction of extension of the panels 62). However, it should be appreciated that the three-dimensional arrangement of the web structure 50 is not limited to such an orientation or arrangement of the open lattice panels 60, 62 relative to the spanwise, chordwise and thickness-wise directions of the blade 20. Furthermore, while the web structure 50 is illustrated as having two spanwise panels 60, this is merely illustrative, as the web structure 50 may have more than two spanwise panels 60 extending along the length of the blade 20, as will be discussed in more detail below. In addition, the number of chord-wise panels 62 and their corresponding locations along the length of the blade 20 may also vary, as will be discussed in more detail below.

Each of the spanwise panels 60 includes a plurality of fiber composite axes in different orientations that intersect each other at a plurality of nodes within a main plane generally defined by the spanwise panel 60. However, in exemplary embodiments, the axes in the spanwise panel 60 may be arranged relative to the spanwise direction of the panel 60 (i.e., the direction of extension of the panel). For example, the fiber composite axes of the spanwise panel 60 may include a normal axis 64 and a staggered axis 66 relative to the spanwise direction of the spanwise panel 60. In an exemplary embodiment, normal axes 64 may be substantially perpendicular to the spanwise direction, while staggered axes 66 may be disposed at +/-45 degrees in a crisscrossed fashion relative to the spanwise direction of spanwise panel 60. However, in alternative embodiments, other uniform and/or non-uniform angles of the staggered axes 66 are possible. In one embodiment, the spanwise panel 60 may include only or primarily the staggered axles 66. However, in alternative embodiments, spanwise panel 60 may include a combination of staggered axes 66 and normal axes 64. In one embodiment, the distribution of the normal axes 64 in the spanwise direction of the spanwise panel 60 may vary depending on various factors including the expected local load conditions on the blade 20, and more particularly the shear web 44. For example, the position of the normal axis 64 in the spanwise direction of the spanwise panel 60 may be determined based on a furnace (brazier) load of the shear web 44.

FIG. 5 is a schematic view of a characteristic load condition of the shear web 44 in the spanwise direction during use of the wind turbine blade 20. In this figure, the x-coordinate represents the spanwise direction of the shear web 44; l is the length of the shear web 44; s is the local load on the shear web 44 as a function of distance x in the spanwise direction; x is x ^* Is based on the normalized x-coordinate (i.e., x ^* =x/L); and S is ^* Is based on the normalized load of the maximum load experienced by the shear web 44 in the spanwise direction (i.e., S ^* ＝S(x)/S _max ). As shown in FIG. 5, the location of maximum load in the shear web 44Usually in the outer half of the shear web 44, i.e.>More specifically, for example, the location of the maximum load may be +.>Between them. The trend shown in fig. 5 is that the load at the root end 26 is relatively low (and may even change direction adjacent the root end 26), increasing toward the mid-blade region, and continuing to increase until the maximum load is reached in the outboard region of the blade 20. From the point of maximum load, the load then decreases in the direction of the tip 28 of the blade 20.

Generally, according to one aspect of the invention, there are more normal axes 64 in the high load regions of the shear web 44 and fewer normal axes 64 in the low load regions of the shear web 44. Thus, adjacent normal axes 64 will be spaced closer to each other in the high load region of the shear web 44, and adjacent normal axes 64 will be spaced further apart from each other in the low load region of the shear web 44. FIG. 6 is a view along the length L of wind turbine blade 20 _b Schematic view of the spanwise panel 60 of the extended shear web 44. As shown, the spacing between adjacent normal axes 26 adjacent the root end 26 of the blade 20 may be relatively large (tall). However, the relative spacing between adjacent normal axes 64 begins to decrease in the spanwise direction toward the maximum load position. Thereafter, the spacing between adjacent normal axes 64 again begins to increase in the spanwise direction toward the tip end 28 of the blade 20.

FIG. 7 is a schematic illustration of a normal axis 64 in the spanwise direction of the shear web 44 in accordance with an aspect of the present inventionSchematic representation of the density distribution. In this figure ρ _ns Is the local density, i.e., the mass of the fiber composite forming the normal axis 64 per unit volume of the spanwise panel 60 as a function of the distance x in the spanwise direction of the shear web 44; andis based on the normalized density of the maximum density value along the spanwise panel 60 (i.e. +.>). As shown in fig. 7, in an exemplary embodiment, the distribution of the normal axis 64 in the spanwise direction of the shear web 44 may be such that the normalized density distribution of the normal axis 64 is relative to the location of maximum load in the shear web 44 (i.e., the maximum of the density distribution is located ∈>) Is a substantially random distribution of (a) to (b). The distribution of normal axes 64 in the spanwise panel 60 according to fig. 7 is only one possible distribution based on the expected load conditions of the wind turbine blade 20 (and more particularly the shear web 44). Thus, it should be appreciated that other distributions that accommodate strength requirements based on anticipated load conditions are possible and remain within the scope of the invention.

In one embodiment, the distribution of the staggered axles 66 in the spanwise direction of the spanwise panel 60 may also vary depending on the expected local load conditions on the shear web 44. For example, the position of the staggered shafts 66 may be determined based on the shear load of the shear web 44. For the characteristic load distribution on the shear web 44 as shown in FIG. 5, in accordance with an aspect of the present invention, adjacent staggered shafts 66 will be spaced closer to each other in the high load region of the shear web 44 and the adjacent staggered shafts 66 will be spaced farther apart in the low load region of the shear web 44. Turning to the drawings, a wind turbine blade 20 along a length L is illustrated _b In FIG. 6 of the spanwise panel 60 of the extended shear web 44, the spacing between adjacent staggered shafts 66 may be relatively high adjacent the root end 26 of the blade 20. However, adjacent interlacesThe relative spacing between the shafts 66 begins to decrease in a direction toward the maximum load position. Thereafter, the spacing between adjacent staggered shafts 66 again begins to increase toward the tip end 28 of the blade 20.

FIG. 8 is a schematic illustration of a characteristic density profile of the staggered axes 66 along the length of the shear web 44 in accordance with an aspect of the present invention. In this figure ρ _cs Is the local density, i.e., the mass of the composite material forming the staggered axes 66 per unit volume of the spanwise panel 60 as a function of the distance x in the spanwise direction of the shear web 44; and Is based on the normalized density of the maximum density value along the spanwise panel 60 (i.e.,/i>). As shown in FIG. 8, in an exemplary embodiment, the distribution of the stagger axes 66 in the spanwise direction of the shear web 44 may be such that the normalized density distribution of the stagger axes 66 may be relative to the location of maximum shear load in the blade 20 (i.e., the maximum of the distribution is at +.>) Is a substantially random distribution of (a) to (b). The distribution of the staggered axles 66 in the spanwise panel 60 according to fig. 8 is only one possible distribution based on the expected load conditions of the wind turbine blade 20 (and more particularly the shear web 44). Thus, it should be appreciated that other distributions that accommodate strength requirements based on anticipated load conditions are possible and remain within the scope of the invention.

Turning now to the chord-wise panels 62, in a similar manner and in the broadest scope, each of these panels includes a plurality of fiber composite axes in different orientations that intersect each other at a plurality of nodes in a main plane generally defined by the chord-wise panels 62. In an exemplary embodiment, the axes in the chord-wise panel 62 may be arranged with respect to the chord-wise direction of the panel 62. For example, the fiber composite axes of the chord-wise panels 62 may include staggered axes 68 relative to the chord-wise direction of the panels 62 (i.e., the direction of extension of the panels 62). In one embodiment, the staggered axles 68 may be disposed at +/-45 degrees relative to the chordwise direction of the panel 62. However, in alternative embodiments, other uniform and/or non-uniform angles of the staggered axes 68 are possible. The chord panel 62 may also include a normal axis 70 that is substantially perpendicular to the chord direction, depending on, for example, the length of extension of the chord panel 62 in the chord direction. In one embodiment, the normal axis 64 of the spanwise panel 60 may also be used as the normal axis 70 of the chordwise panel 62 (see FIG. 4). However, aspects of the invention are not limited in this regard as chordwise panel 62 may include a normal axis 70 that does not correspond to normal axis 64 in spanwise panel 60. For example, fig. 4 illustrates having a normal axis 70 (shown in phantom) that does not correspond to normal axis 64 in spanwise panel 60. In one embodiment, the chord panel 62 may include only or primarily the staggered axles 68. However, in alternative embodiments, chord panel 62 may include a combination of staggered axes 68 and normal axes 70. In one embodiment, the distribution of the axles 68, 70 along the extension length of the chord-wise panel 62 may be based on a number of factors including providing a more uniform load distribution across the width of the shear web 44 and across the bonding area between the flanges 46, 48 and the respective spar caps 40, 42.

FIG. 9 is a schematic view of a characteristic load condition of the shear web 44 in a chordwise direction during use of the wind turbine blade 20. In this figure, the y-coordinate represents the chordwise direction of the wind turbine blade 20; w is the width of the shear web 44 in the chordwise direction; t is the local load of the shear web 44 in the chord-wise direction of the blade 20; y is ^* Is based on the normalized y-coordinate (i.e., y ^* ＝y/W)；T ^* Is based on the normalized load of the maximum load experienced by the shear web 44 in the chordwise direction (i.e., T ^* ＝T(y)/T _max ). The dashed curve a in fig. 9 represents an exemplary characteristic load condition on a conventional shear web having an I-shaped profile. As discussed above, the characteristic load conditions have a maximum shear load near the central portion of the shear web (where the intermediate web is located) (i.e.,) While the vast majority of the load is carried over a relatively small portion of the width of the shear web very close to the intermediate web.

For example, curve B in fig. 9 represents an exemplary characteristic load condition in the shear web 44 shown in fig. 4. As shown in FIG. 9, the maximum shear load location in the shear web 44 generally occurs at the location of the spanwise panel 60, with two spanwise panel locations in FIG. 4, i.e., on the leading and trailing edge sides of the web structure 50. The presence of the chord-wise panels 62 facilitates distribution of the load at the spanwise panels 60 in the chordwise direction to provide a more uniform load distribution in the chordwise direction. Furthermore, in the exemplary embodiment, spanwise panel 60 of web structure 50 is preferably located adjacent to edges of flanges 46, 48 of shear web 44 such that web structure 50 extends over a majority of the width of flanges 46, 48. For example, web structure 50 may have a width that is greater than 70% of the width of flanges 46, 48, preferably greater than 80% of the width, and even more preferably greater than about 90% of the width. The lower and upper flanges 46, 48 may in turn extend a majority of the width of the spar caps 40, 42, such as extending more than 70% of the width of the spar caps 40, 42, preferably more than 80% of the width, and even more preferably more than 90% of the width. This arrangement not only increases the bond area between the spar caps 40, 42 and the flanges 46, 48 of the shear web 44, but also provides a more even distribution of the load acting on the bond area.

The trend shown in fig. 9 is that the shear load is relatively large on the leading and trailing edge sides of the shear web 44 (due to the position of the spanwise panel 60) and decreases towards the intermediate region of the shear web 44. However, the amount of load reduction away from the spanwise panels 60 is not significant due to the chordwise panels 62, and a portion of the load is distributed over and carried by these chordwise panels 62. Peak loads are significantly reduced and the area over which the loads are distributed is significantly increased compared to the I-shaped shear web depicted by curve a.

In one embodiment, the distribution of staggered axles 68 in the chord-wise panel 62 may remain relatively constant in that direction. FIG. 10 is an illustration of the characteristic density distribution of the staggered axles 68 in the chordwise direction y of the chordwise panel 62A drawing. In this figure ρ _cs Is the local density, i.e., the mass of the composite material forming the staggered axles 68 per unit volume of the chord-wise panel 62 as a function of the distance y in the chord-wise direction; andis based on the normalized density of the maximum density value along the chord-wise panel 62 (i.e). Curve a in fig. 10 illustrates an embodiment in which the staggered axles 68 are substantially uniform across the chordwise panel 62.

However, in alternative embodiments, the distribution of the staggered axles 68 in the chord-wise panel 62 may vary depending on the expected local load conditions on the shear web 44. For a load distribution on the shear web 44 as shown by curve B in fig. 9, there may be more staggered axes 68 in the high load regions of the shear web 44 and less staggered axes 68 in the lower load regions of the shear web 44. In other words, adjacent staggered shafts 68 will be spaced closer to each other in the high load regions of the shear web 44, while adjacent staggered shafts 68 will be spaced further apart from each other in the lower load regions of the shear web 44. Thus, for example, the spacing between adjacent staggered axles 68 adjacent the leading and trailing edge sides of the chord-wise panel 62 may be relatively small. However, the spacing between adjacent staggered shafts 68 may increase in a direction toward the intermediate region of the shear web 44.

Curve B in fig. 10 is a schematic representation of the characteristic density distribution of the staggered axles 68 in the chordwise direction of the web structure 50 in such an alternative embodiment. As shown by the graph, in an exemplary embodiment, the distribution of the staggered axles 68 in the chord-wise panel 62 may be such that the normalized density distribution of the staggered axles 68 is greatest on the leading and trailing edge sides and decreases to a relatively constant level toward the intermediate region. The distribution of the staggered axles 68 in the chord-wise panel 62 according to curves a and B of fig. 10 is merely two possible distributions. Thus, it should be appreciated that other distributions based on load uniformity, expected load conditions, etc. are possible and remain within the scope of the present invention.

As described above, while the chord-wise panels 62 shown in FIG. 4 include normal axes 70 only on the leading and trailing edge sides of the web structure 50, additional normal axes 70 may be distributed along the chord-wise direction of the chord-wise panels 62 of the web structure 50. Similar to the above, this distribution may be constant in the chordwise direction or may vary in the chordwise direction depending on the expected local load conditions on the shear web 44, such as the expected local load conditions shown in FIG. 9. Thus, the density profile of normal axis 70 in chord panel 62 may be as shown in FIG. 11 where curve A illustrates a uniform density profile of normal axis 70 and curve B illustrates a varying density profile of normal axis 70. For example, in the latter embodiment, more normal axes 70 may be positioned adjacent the leading and trailing edge sides of the panel 62 (with less spacing between adjacent axes 70), while fewer normal axes 70 may be positioned in the middle region of the panel 62 (with greater spacing between adjacent axes 70). The distribution of normal axes 70 in chord panel 62 according to fig. 11 is only two possible distributions. Thus, it should be appreciated that other distributions of normal axes 70 in chordwise panel 62 that accommodate uniformity, expected loading conditions, etc. are possible and remain within the scope of the invention.

In one embodiment (not shown), the chord-wise panels 62 may be evenly distributed along the spanwise direction of the shear web 44. However, in another embodiment, the distribution of the chord-wise panels 62 in the spanwise direction of the shear web 44 may vary depending on the expected local load conditions on the shear web 44. Referring back to fig. 5, fig. 5 illustrates the characteristic load conditions of the shear web 44 in the spanwise direction during operation. Thus, in general and in accordance with one aspect of the invention, there will be more chordwise panels 62 in the high load regions of the shear web 44, and fewer chordwise panels 62 in the lower load regions of the shear web 44. The concept can also be best visualized with reference to fig. 6. In this regard, it is contemplated that each normal axis 64 shown in the figures is associated with a chord-wise panel 62 that extends into the page and is therefore not visible from the perspective of the figure.

FIG. 12 shows the chord panel 62 in shearA schematic representation of the characteristic density profile in the spanwise direction of the web 44. In this figure ρ _cp Is the local density of the chord-wise panel, i.e. the mass of composite material forming the chord-wise panel 62 per unit volume of the web structure 50 in the spanwise direction of the shear web 44; and Is based on the normalized density of the maximum density value in the spanwise direction of the web structure 50 (i.e +.>). As shown in fig. 12, in an exemplary embodiment, the distribution of the chord-wise panels 62 in the spanwise direction of the web structure 50 may be such that the normalized density distribution of the chord-wise panels 62 is relative to the location of maximum load in the web structure 50 (i.e., the maximum of the distribution is located +.>) Is a substantially random distribution of (a) to (b). The distribution of the chord-wise panels 62 in the spanwise direction according to fig. 12 is only one possible distribution based on the expected loading conditions of the wind turbine blade 20 and the shear web 44. Thus, it should be appreciated that other distributions that accommodate strength requirements based on anticipated load conditions are possible and remain within the scope of the invention.

The above discussion generally describes possible distributions of staggered axes 68 and possibly normal axes 70 in the chordwise direction of chordwise panel 62. However, variations in the chord-wise panels 62 as a function of their position in the spanwise direction of the web structure 50 should also be considered. For example, in one embodiment, the chord-wise panels 62 may be identical regardless of their position in the spanwise direction of the web structure 50. That is, each chord-wise panel 62 has the same staggered axis 68 (and perhaps normal axis 70) distribution. However, in alternative embodiments, the chord-wise panels 62 may vary depending on the position of the panels 62 in the spanwise direction of the web structure 50. For example, such variations may depend on the expected local load conditions on the web structure 50.

By way of example, and not limitation, based on the characteristic load distribution shown in FIG. 5, the density of staggered axles 68 in the chordwise panel 62 in low load regions (such as adjacent the root end 26 of the blade 20) may be less than in high load regions (such as in the outboard portion of the blade (e.g.)) A density of staggered axles 68 in the chordwise panel 62). Fig. 13A and 13B schematically reflect this general relationship. More specifically, FIG. 13A illustrates a chord-wise panel 62 having a relatively low density of staggered axles 68, which chord-wise panel 62 may be more suitable for positioning adjacent the root end 26 of the blade 20 where a lower load is expected. On the other hand, FIG. 13B illustrates a chord-wise panel 62 having a relatively higher density of staggered axles 68, which chord-wise panel 62 may be more suitable for positioning in the outboard region of the blade 20 where higher loads are expected.

Thus, the density of the staggered axles 68 in the chord-wise panel 62 may vary as a function of spanwise location. This variation may be illustrated in the exemplary embodiment shown in fig. 14. As shown in this figure, the density of the staggered axles 68 in the chord-wise panels 62 may be such that the normalized density distribution is with respect to the location of maximum load in the web panels 62 (i.e., the maximum of the distribution is located at) Is a substantially random distribution of (a) to (b). The distribution according to fig. 14 is only one possible distribution based on the expected load conditions of the wind turbine blade 20 and the web structure 50. Thus, it should be appreciated that other distributions that accommodate strength requirements based on anticipated load conditions are possible and remain within the scope of the invention. If the chord-wise panel 62 also includes a distribution of normal axes 70, the density of the normal axes 70 in the panel 62 may likewise vary based on the position of the web structure 50 in the spanwise direction. Thus, the chord-wise panels 62 in the low load regions will include fewer normal axes than the chord-wise panels 62 in the high load regions. The density of normal axes 70 in chord panel 62 may similarly have a substantially random distribution with respect to the location of maximum load in web structure 50.

As described above, although the web structure 50 shown in fig. 3 and 4 includes two spanwise panels 60 only on the leading and trailing edge sides of the web structure 50, there may be additional spanwise panels 60 distributed in the chordwise direction of the web structure 50. For example, fig. 15 illustrates a web structure 50 having more than two spanwise panels 60 (e.g., 8 spanwise panels 60) distributed in a chordwise direction of the web structure 50. The concept may be better visualized by imagining that each normal axis shown in the figure is associated with a spanwise panel 60 that extends into the page and is therefore not visible from the perspective of the figure. In an exemplary embodiment, as shown in fig. 15, spanwise panels 60 may be evenly distributed in a chordwise direction of web structure 50. Similar to that shown in FIG. 9, FIG. 16 is a schematic illustration of the characteristic load conditions on the shear web 44 in the chordwise direction of the web structure 50. Similar to the above, the maximum shear load is located at the spanwise panels 60 and is slightly reduced between the spanwise panels 60. However, adding more spanwise panels 60 further reduces peak shear loads and distributes the loads more evenly across the shear web 44 in the chordwise direction. The distribution of spanwise panels 60 in the chordwise direction according to fig. 15 and 16 is only one possible distribution. Thus, it should be appreciated that other distributions that accommodate load uniformity, expected load conditions, etc. are possible and remain within the scope of the present invention.

The above discussion generally describes a possible distribution of normal axes 64 and staggered axes 66 in the spanwise direction of spanwise panel 60 (see, e.g., fig. 6). However, variations in the spanwise panel 60 as a function of their position in the chordwise direction of the web structure 50 should also be considered. For example, in the exemplary embodiment, spanwise panels 60 may be identical regardless of their location along the chordwise direction of web structure 50. That is, each spanwise panel 60 has the same normal axis 64 and/or staggered axis 66 distribution. However, in alternative embodiments, the spanwise panel 60 may differ depending on the location of the panel 60 along the chordwise direction of the web structure 50.

Based on the above, the design of the three-dimensional open lattice configuration of the web structure 50 provides a number of methods to vary the strength depending on the expected load conditions on the shear web 44. The general idea is that in higher load regions of the web structure 50, the web structure 50 may comprise more fiber composite shafts, while in lower load regions of the web structure 50, the web structure 50 may comprise fewer fiber composite shafts. The three-dimensional arrangement of the web structure 50 may be achieved by providing a plurality of first open cell panels 60 intersecting a plurality of second open cell panels 62. The plurality of first panels 60 may be spanwise panels extending generally in a spanwise direction, while the plurality of second panels 62 may be chordwise panels extending generally in a chordwise direction. Each panel 60, 62 includes a plurality of fiber composite axes extending in a main plane defined by the panels 60, 62. For example, the spanwise panel 60 may include staggered axes 66 and possibly normal axes 64 having an orientation relative to the spanwise direction of the spanwise panel 60. Similarly, the chord-wise panel 62 may include alternating axes 68 and possibly normal axes 70 having an orientation relative to the chord-wise direction of the chord-wise panel 62.

The strength of the web structure 50 may be reinforced in different ways in the high load areas. For example, for high load regions in the spanwise direction, the local strength of the web structure 50 may be increased by one or more of the following: i) Increasing the number of chord panels 62; ii) increasing the normal axis and/or staggered axis density in chordal panel 62; and iii) increasing the normal and/or staggered axis density in spanwise panel 60. Further, in the chordwise direction, local variations in load uniformity or strength of the web structure 50 may be accommodated by: i) Increasing the number of spanwise panels 60 distributed in the chordwise direction; and ii) increasing the normal and/or staggered axial density in the chord-wise panel 62. Accordingly, it should be appreciated that the designer has a number of options to provide strength variation of the web structure 50 to accommodate expected load conditions on the wind turbine blade 20 and the shear web 44 during operation of the wind turbine 10, and a number of options to provide a more uniform load distribution on the shear web 44 and on the bonding areas between the flanges 46, 48 and the spar caps 40, 42.

In this regard, it should be appreciated that a designer may use any combination of the options described above to alter the strength response of the web structure 50. By providing the web structure 50 with a three-dimensional open lattice configuration formed from fiber composite shafts, not only can strength be more tailored to the anticipated load conditions, but the weight of the web structure 50 can be reduced as compared to conventional molded web structures. Thus, with greater design flexibility, a shear web with a very high strength to weight ratio may be provided for wind turbine blade configurations. This improvement would in turn allow for further increases in the length of the wind turbine blade (and associated energy capture) with reduced weight and reduced cost, while maintaining the structural integrity of the blade.

As mentioned above, one disadvantage of current shear web designs is that forces along the bond area between the flange of the shear web and the spar cap are concentrated along the central area of the flange. Thus, the forces transferred from the housing to the beam structure occur over a relatively small width of the bonding area. The open lattice configuration of the shear web 44 also allows the shear load in the shear web 44 to be more evenly distributed over a larger portion of the spar caps 40, 42 and flanges 46, 48. This reduces peak shear loads in the bonding areas between flanges 46, 48 and spar caps 40, 42. This improvement in load distribution prevents the strength limitation in the bonded area from inhibiting further increases in blade length.

In the foregoing, the flanges 46, 48 of the shear web 44 are described as being conventional, having a laminated composite construction, while the web structure 50 has a three-dimensional open lattice construction. In another embodiment, flanges 46, 48 may have an open lattice configuration while the web structure has a conventional laminated composite configuration. In yet another embodiment, the flanges 46, 48 and the web structure 50 (i.e., substantially the entire shear web 44) may have a multi-dimensional open lattice configuration similar to that described above.

In this regard, fig. 17 illustrates a shear web 44 having a lower flange 46, an upper flange 48, and an intermediate web structure 50 (shown schematically) extending between the lower flange 46 and the upper flange 48. In this embodiment, lower flange 46 and upper flange 48 have an open lattice construction of fibrous composite material similar to panels 60, 62 described above. The open lattice construction includes a plurality of elongated structural members composed of fibrous composite material that are interdigitated to form a network of interconnected shafts that together form flanges 46, 48. Accordingly, the flanges 46, 48 according to aspects of the present invention are not of solid construction as in conventional shear web molded flange structures or pultruded flange structures, but rather include a lattice arrangement with selectively located shafts and void spaces. The concept embodied in the open lattice configuration is that the load carrying capacity of flanges 46, 48 may be significantly increased, such as by the arrangement of the axles, while minimizing the overall weight of flanges 46, 48 by having a large amount of void space.

Similar to the above, the open lattice configuration of flanges 46, 48 not only provides increased strength at lower weights, but also provides increased design flexibility through the local placement of the axles based on estimated local load conditions. Thus, with the arrangement of the fiber composite shaft, flanges 46, 48 may be configured to have high strength in localized areas subjected to high load conditions and reduced strength in localized areas subjected to lower load conditions. In other words, flanges 46, 48 may include a greater number of axles per unit volume in the expected high load region, while flanges 46, 48 may include fewer axles per unit volume in the expected low load region. The lattice arrangement of the flanges 46, 48 of the shear web 44 in this embodiment may also be formed by the continuous fiber reinforced additive manufacturing method described above.

The open lattice configuration of flanges 46, 48 may include panels 71 similar to panels 60, 62 described above but having an orientation with panels 71 facing the windward and leeward sides of blade 20, rather than toward leading edge 34 and trailing edge 36 of blade 20. More specifically, the panels 71 may be arranged such that the major plane of the panels extends in the spanwise direction x and chordwise direction y, with a significantly smaller extension of the panels 71 extending in the thickness direction z. Flanges 46, 48, and thus panel 71, may be considered to extend generally along the length of blade 20 in the spanwise direction (i.e., the direction in which panel 71 extends). Each of the panels 71 defining the flanges 46, 48 includes a plurality of fiber composite axes in different orientations that intersect each other at a plurality of nodes in a main plane generally defined by the panels 71. However, in an exemplary embodiment, the axes in the panel 71 may be arranged with respect to the spanwise direction of the panel 71. For example, the fiber composite axes of the face sheet 71 may include a normal axis 72 and an alternating axis 74 relative to the spanwise direction of the face sheet 71. In an exemplary embodiment, the normal axis is substantially perpendicular to the spanwise direction, and the staggered axes 74 may be arranged in a crisscrossed fashion +/45-degrees with respect to the spanwise direction of the panel 71. However, other uniform and/or non-uniform angles of the staggered axes 74 are also possible. The panel 71 defining the flanges 46, 48 may also include edge axles 76 positioned on the leading and trailing sides of the flanges 46, 48. However, the edge axles may be omitted from the flanges 46, 48. In one embodiment, the faceplate 71 may include only or primarily the interlaced axle 74. However, in alternative embodiments, the face plate 71 may include a combination of staggered axes 74 and normal axes 72.

Similar to above, the distribution of normal and staggered axes 72, 74 in the spanwise direction of the flanges 46, 48 may vary depending on the anticipated local load conditions on the shear web 44 (and more specifically the flanges 46, 48). Thus, normal shaft 72 may vary in density in the spanwise direction of flanges 46, 48, with higher density in the high load areas and lower density in the lower load areas. Additionally or alternatively, the density of staggered axles 74 may vary in the spanwise direction of flanges 46, 48, with higher densities in high load areas and lower densities in lower load areas. Accordingly, manufacturers also have several options in designing the flanges 46, 48 of the shear web 44 based on anticipated loading conditions. By providing flanges having an open lattice configuration formed by the fiber composite shafts 72, 74, 76, not only can the strength be more tailored to the anticipated load conditions, but the weight of the flanges 46, 48 can be reduced as compared to conventional molded web structures. Accordingly, the flanges 46, 48 of the shear web 44 may be provided for wind turbine blade configurations with very high strength to weight ratios.

Furthermore, providing the flanges 46, 48 as an open lattice configuration may also improve the connection of the shear web 44 to the spar caps 40, 42 of the spar structure 24. When flanges 46, 48 are bonded to beam caps 40, 42, as shown in fig. 18, sufficient pressure may be applied such that flanges 46, 48 are immersed or embedded in the adhesive used to form the bond. In this way, the adhesive interface becomes three-dimensional. This is in contrast to solid planar flanges in conventional shear webs, where the bond interface is two-dimensional (i.e., the bond is formed between the adhesive and the generally planar surface of the flange). Furthermore, while flanges 46, 48 in this embodiment are not solid but lattice in configuration, the total adhesive surface area between the adhesive and the flanges may be increased due to the adhesive contacting most or all of the surfaces of shafts 72, 74, 76 of flanges 46, 48. Regardless, it is believed that by configuring the flanges 46, 48 as an open lattice structure, the bond between the shear web 44 and the spar caps 40, 42 will be improved for one or both of these reasons.

As described above, various embodiments employ hybrid shear web design methods in which portions of the shear web include, for example, 3D printed lattice structures, which are complementary to other portions of the shear web 44 formed by more conventional processes. For example, embodiments were discussed in detail above in which the flanges 46, 48 of the shear web 44 are of conventional construction, but the web structure 50 has a three-dimensional open lattice design. Another embodiment is described above in which the flanges 46, 48 of the shear web 44 have an open lattice design, but the web structure has a conventional configuration. FIG. 19 is a cross-sectional view of another hybrid shear web 44, the shear web 44 having conventional sections and an open lattice structure formed by a continuous fiber-reinforced additive manufacturing process in accordance with aspects of the present invention.

In this regard, the shear web 44 includes a lower flange 46, an upper flange 48, and an intermediate web structure 50 extending between the lower flange 46 and the upper flange 48. The intermediate web structure 50 may have a conventional construction consisting of fibrous layers, core material and resin. Upper flange 46, lower flange 48 may be conventional and have a laminated composite construction. Alternatively, the upper and lower flanges may be formed by a pultrusion process. For example, the shear web 44 may be formed by a conventional molding process.

The conventionally fabricated shear web 44 (so far) includes a web structure 50 having a first face 90 generally facing the leading edge 34 of the blade 20 when the shear web 44 is in an operational position within the blade 20, and a second face 92 generally facing the trailing edge 36 of the blade 20. In this embodiment, an open lattice structure 94 may be formed on at least one of the first and second faces 90, 92 of the web structure 50, preferably on both of the first and second faces 90, 92. The addition of the open lattice structure 94 to at least one face 90, 92 of the web structure 50 may be by a continuous fiber reinforced additive manufacturing process. In this regard, at least one face 90, 92 may face the printhead of a 3-D printer, while the open lattice structure 94 is printed directly on at least one face 90, 92 of the web structure 50. The open lattice structure 94 is constructed in a similar manner to the spanwise panel 60 of the web structure 50 described above and includes a plurality of normal (e.g., vertical) axes 96 and staggered axes 98 that intersect one another at a plurality of junctions in the major plane defining the panel.

Similar to the discussion above, the density of normal axes 96 and/or the density of staggered axes 98 may vary in the spanwise direction depending on the local load conditions on web structure 50. Thus, the density of normal axes 96 may vary in the spanwise direction of web structure 50, with higher densities in high load areas and lower densities in lower load areas. Additionally or alternatively, the density of the staggered shafts 98 may vary in the spanwise direction of the web structure 50, with higher densities in high load areas and lower densities in lower load areas. Accordingly, manufacturers also have a number of options in designing the web structure 50 of the shear web 44 based on anticipated loading conditions. While the inclusion of the open lattice structure 94 on at least one face 90, 92 of the web structure 50 increases weight, the overall strength of the shear web 44 increases. Thus, a single shear web according to the present design may replace a spar structure having multiple shear webs (i.e., a spar structure having fewer shear webs). Thus, the total weight of the beam structure can be reduced.

In alternative embodiments, an open lattice structure 100 similar to the structure 94 may be formed on the flanges 46, 48 of the shear web 44 (such as on the outer (face) 108 of the flanges 46, 48) in addition to the open lattice structure 94 formed on at least one face 90, 92 of the web structure 50. These open lattice structures 100 provide increased strength to the flanges 46, 48 and may improve the adhesion of the flanges 46, 48 to the beam caps 40, 42 of the beam structure 24. Due to the load carrying capacity of the open lattice structure 100, the overall length of the flanges 46, 48 in the thickness direction may also be reduced. In yet another embodiment, an open lattice structure 100 may be formed on flanges 46, 48, wherein the web structure is of conventional design without an open lattice structure 94 formed thereon. Thus, in at least some of the hybrid embodiments, the open lattice structures 94, 100 may be selectively added to various portions of the conventionally fabricated shear web 44 (including along at least some portions of the web structure 50 and/or flanges 46, 48) to increase strength.

The design freedom provided to the shear web as a result of continuous fiber-reinforced additive manufacturing may provide other advantages and address other problems associated with shear web designs for wind turbine blades. For example, one problem is that near the root end of a wind turbine blade, shear webs are often subjected to relatively high peel loads. Due to the design flexibility provided by aspects of the present invention, the peel load at the root end of the blade may be reduced by providing a force path that extends primarily in the spanwise direction of the shear web. In an exemplary embodiment, this may be achieved by two means. First, as shown in FIG. 22, the shear web 44 may include a portion of the flanges 46, 48 extending beyond the intermediate web structure 50 in the spanwise direction at the root end 26 of the blade 20 (i.e., there is no corresponding web structure between two opposing flanges). A portion of the flanges 46, 48 is referred to herein as a flange extension piece 104.

Second, as also shown in FIG. 20, in the transition region 106 of the intermediate web structure 50 adjacent the root end 26 of the blade 20, both in the chordwise panel 62 extending away from the flanges 46, 48 and in the spanwise panel 60, the composite axes 64, 66, 68, 70 become locally curved or bent (i.e., swept) in a smooth manner so as to intersect the flanges 46, 48 at a reduced angle θ. The angle θ preferably tapers in the spanwise direction in a direction toward the end of the web structure 50 (adjacent the root end 26 of the blade 20). The localized and gradual bending (referred to herein as a scalloped configuration) of the axes 64, 66, 68, 70 of the web structure 50 extending from the flanges 46, 48 in the transition region 106 of the shear web 44 adjacent the root end 26 of the blade 20 provides a force path more tangential to the plane defined by the flanges 46, 48. Thus, the force is directed more in the spanwise direction of flanges 46, 48 than in the lateral or vertical direction. This localized force redirection in the transition region 106 reduces the peel forces on the flanges 46, 48 of the shear web 44 adjacent the root end 26 of the blade 20.

The extension sheets 104 of the flanges 46, 48 not only facilitate the scalloped configuration of the axis of the web structure 50 adjacent the root end 26 of the blade 20, but also provide a more convenient area to provide additional securement of the shear web 44 to the blade root interior surface. For example, FIG. 21A illustrates an embodiment in which the extension sheet 104 is used in a lamination process that utilizes one or more fiber layers 110 and resin to further secure the shear web 44 to the shell 22 at the root end 26 of the blade 20. Fig. 21B illustrates another embodiment in which extension piece 104 has a widened portion 112 (i.e., an increased width compared to the width of the flanges at the portion where the web structure is present), which widened portion 112 moves at least a portion of the length of extension piece 104 toward the ends of flanges 46, 48 (e.g., extends over 70%, preferably over 80% of the length of extension piece 104). This configuration, referred to herein as a fin configuration, provides an increased area for adhesively bonding the shear web 44 to the shell 22 at the root end 26 of the blade 20. The lamination process may also be used to provide additional fastening (not shown) of the shear web 44 at the root end 26 of the blade 20. It should be appreciated that the above-described configuration of extension piece 104 of flanges 46, 48 is applicable to flanges conventionally manufactured by, for example, a molding process, or flanges 46, 48 configured as an open lattice structure manufactured by, for example, a continuous fiber-reinforced additive manufacturing process as described above.

As the length of wind turbine blades continues to increase, logistics for manufacturing and transporting such elongated structures becomes more and more complex. The continued expansion of wind turbine blades and their manufacturing equipment has inherent and practical limitations. To address these limitations, segmented wind turbine blades have been developed that divide the blade into a plurality of segments that are joined end-to-end to form the wind turbine blade. For example, FIG. 2 illustrates a wind turbine blade 20 formed from a plurality of blade segments 116 joined to one another at a connection interface 118. The connection interface 118 between adjacent blade segments 116 may present a weak point in the structural integrity of the wind turbine blade 20 and, thus, is often reinforced to allow for the application and transfer of loads on the blade 20 in the area surrounding the connection interface 118.

In this regard, the shear webs 44 in the respective blade segments 116 may be configured to overlap or nest in some manner to provide strength at the connection joints 118 between the segments 116. Fig. 22 and 23 illustrate a segmented wind turbine blade 20 in which the web structure 50a from one blade segment 116a and the web structure 50b from an adjacent blade segment 116b have an overlapping or nested relationship. In this regard, the web structure 50a includes a groove 120, while the web structure 50b includes an extension 122, and when the blade segments 116a, 116b are connected to one another at the connection interface 118, the extension 122 is configured to be received in the groove 120.

In this embodiment, the configuration of the web structure 50a in the first blade section 116a and the web structure 50b in the second blade section 116b are configured to mate such that when the extension 122 is received in the groove 120, the axes forming the web structures 50a and 50b are aligned with each other. For example, fig. 23 schematically illustrates how the staggered axes 66 in the spanwise panel 60 of the web structure 50a align with the staggered axes 66 in the corresponding spanwise panel 60 of the web structure 50 b. By aligning the axes of the web structure between the first and second blade segments 116a, 116b, the force path between the lower and upper flanges 46, 48 remains continuous over the connection joint 118. This makes the connection between the blade sections 116a, 116b more secure.

While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Thus, the various features of the invention may be used alone or in any combination depending on the needs and preferences of the user.

Claims

1. A shear web (44) for a wind turbine blade (20), the shear web (44) comprising:

a lower flange (46);

an upper flange (48); and

a web structure (50) extending between the lower flange (46) and the upper flange (48),

wherein at least one of the lower flange (46), the upper flange (48) and the web structure (50) comprises an open lattice structure (60, 62, 71, 94, 100) having a plurality of elongated fiber composite axes (64, 66, 68, 70, 72, 74, 96, 98) intersecting each other at a plurality of junctions of the open lattice structure.

2. The shear web (44) of claim 1, wherein the web structure (50) comprises a three-dimensional open lattice structure (60, 62), and wherein the plurality of elongate fiber composite axes (64, 66, 68, 70) extend in three-dimensional space.

3. The shear web (44) of claim 2, wherein the web structure (50) comprises:

a plurality of first open lattice panels (60), each of the plurality of first panels (60) comprising a plurality of axes (64, 66) extending in a plane defined by the panels; and

a plurality of second open lattice panels (62), each of the plurality of second panels (62) including a plurality of axes (68, 70) extending in a plane defined by the panels,

Wherein the plurality of first panels (60) intersect the plurality of second panels (62) at a plurality of junctions to define the three-dimensional open lattice structure.

4. A shear web (44) according to claim 3, wherein each of the plurality of first panels (60) defines a first direction of extension and comprises a plurality of axes (66) that are not perpendicular to the first direction of extension.

5. The shear web (44) of claim 4, wherein each of the plurality of first panels (60) further comprises a plurality of axes (64) perpendicular to the first direction of extension.

6. A shear web (44) according to claim 4 or 5, wherein the distribution of axes (64, 66) in the first direction of extension is non-uniform.

7. The shear web (44) of claim 6, wherein in the first extension direction, the density of the shafts (64, 66) in the high load region of the shear web (44) is greater than the density of the shafts (64, 66) in the low load region of the shear web (44).

8. The shear web (44) of any one of claims 3-7, wherein each of the plurality of second panels (62) defines a second direction of extension and includes a plurality of axes (68) that are not perpendicular to the second direction of extension.

9. The shear web (44) of claim 8, wherein each of the plurality of second panels (62) further comprises a plurality of axes (70) perpendicular to the second direction of extension.

10. A shear web (44) according to claim 8 or 9, wherein the distribution of axes (68, 70) in the second direction of extension is substantially uniform.

11. The shear web (44) of claim 10, wherein the density of the shafts (68, 70) in the second direction of extension is substantially uniform.

12. The shear web (44) of any one of claims 3-11, wherein the plurality of second panels (62) are unevenly distributed in the first direction of extension.

13. The shear web (44) of claim 12, wherein in the first direction of extension, a density of the second panel (62) in a high load region of the shear web (44) is greater than a density of the second panel (62) in a low load region of the shear web (44).

14. The shear web (44) of any one of claims 1-13, wherein at least one of the lower flange (46) and the upper flange (48) includes an open lattice panel (71) oriented to extend in the first direction of extension.

15. The shear web (44) of claim 14, wherein the open lattice panel (71) forming the at least one of the lower flange (46) and the upper flange (48) includes a plurality of axes (72, 74) relative to the first direction of extension.

16. The shear web (44) of claim 15, wherein the distribution of axes (72, 74) in the first direction of extension is non-uniform based on load conditions of the shear web (44).

17. The shear web (44) of claim 16, wherein in the first direction of extension, the density of the shafts (72, 74) in the high load region of the shear web (44) is greater than the density of the shafts (72, 74) in the low load region of the shear web (44).

18. The shear web (44) of any one of claims 1-17, wherein ends of the lower flange (46) and the upper flange (48) of the shear web (44) configured to be located adjacent a root end of the wind turbine blade (20) include extension sheets (104).

19. The shear web (44) of claim 18, wherein the extension sheet (104) includes a widened portion (112) configured to increase a bonding surface area of the shear web (44).

20. A shear web (44) according to claim 18 or 19, wherein in a transition region (106) adjacent the end of the shear web (44), the axles (64, 66, 68, 70) extending from the lower and upper flanges (46, 48) have a scalloped configuration.

21. The shear web (44) of claim 1, wherein the web structure (50) has a laminated composite construction, wherein the lower flange (46) and the upper flange (48) have a laminated composite construction or a pultruded construction, and wherein the open lattice structure (94, 100) is formed on at least one surface of the lower flange (46), the upper flange (48) and the web structure (50).

22. The shear web (44) of claim 21, wherein the web structure (50) includes opposed first and second surfaces (90, 92), and wherein the open lattice structure (94) is formed on each surface (90, 92) of the web structure (50).

23. The shear web (44) of claim 21 or 22, wherein each of the lower flange (46) and the upper flange (48) includes an outer surface (108), and wherein the open lattice structure (100) is formed on the outer surface (108) of each of the lower flange (46) and the upper flange (48).

24. A wind turbine blade (20), the wind turbine blade (20) having a shear web (44) according to any one of claims 1-23.

25. The wind turbine blade (20) of claim 24, wherein the blade (20) further comprises a first blade section (116 a) and a second blade section (116 b) configured to join at a connection interface (118),

wherein the first blade section (116 a) and the second blade section (116 b) comprise a first shear web portion (44 a) and a second shear web portion (44 b), respectively,

wherein at least the web structure (50 a) of the first shear web portion (44 a) and the web structure (50 b) of the second shear web portion (44 b) are configured to be connected to each other in a nested relationship when the first blade section (116 a) and the second blade section (116 b) are joined together; and

wherein the arrangement of the shafts (64, 66) in the web structure (50 a) of the first shear web portion (44 a) and the arrangement of the shafts (64, 66) in the web structure (50 b) of the second shear web portion (44 b) are such that the shafts (64, 66) of the shear web (44) are substantially aligned on the connection interface (118).

26. A wind turbine (10), the wind turbine (10) having a wind turbine blade (20) according to claim 25.

27. A method of making a shear web (44) for a wind turbine blade (20), the method comprising:

providing a lower flange (46);

providing an upper flange (48);

providing a web structure (50) configured to extend between the lower flange (46) and the upper flange (48);

forming at least one of the lower flange (46), the upper flange (48) and the web structure (50) in an open lattice structure (60, 62, 71, 94, 100) having a plurality of elongated fiber composite axes (64, 66, 68, 70, 72, 74, 96, 98) intersecting each other at a plurality of junctions of the open lattice structure;

-connecting the lower flange (46) to a lower end of the web structure (50); and

connecting the upper flange (48) to an upper end of the web structure (50),

wherein the open lattice structure is formed by a continuous fiber reinforced additive manufacturing process.

28. The method of claim 27, wherein the forming step further comprises forming the web structure (50) as a three-dimensional open lattice structure (60, 62) having a plurality of elongated fiber composite axes (64, 66, 68, 70) extending in three-dimensional space.

29. The method of claim 28, wherein forming the web structure (50) into a three-dimensional open lattice structure further comprises:

forming a plurality of first open cell panels (60);

forming a plurality of second open lattice panels (62);

orienting the first plurality of open cell panels (60); and

the plurality of second open lattice panels (62) are oriented such that the plurality of first panels (60) intersect the plurality of second panels (62) at a plurality of junctions to define the three-dimensional open lattice structure.

30. The method of claim 29, wherein forming the plurality of first panels (60) further comprises: for each of the plurality of first panels (60), a plurality of axes (66) is formed that is not perpendicular to the first direction of extension of the panels (60).

31. The method of claim 30, wherein forming the plurality of first panels (60) further comprises: for each of the plurality of first panels (60), a plurality of axes (64) perpendicular to the first direction of extension is formed.

32. The method of claim 30 or 31, further comprising unevenly distributing the shafts (64, 66) in the first direction of extension.

33. The method of claim 32, further comprising providing an axle (64, 66) density in the first extension direction in a high load area of the shear web (44) that is greater than an axle (64, 66) density in a low load area of the shear web (44).

34. The method of any of claims 29-33, wherein forming the plurality of second panels (62) further comprises: for each of the plurality of second panels (62), a plurality of axes (68) is formed that is not perpendicular to the second direction of extension of the panels (62).

35. The method of claim 34, wherein forming the plurality of second panels (62) further comprises: for each of the plurality of second panels (62), a plurality of axes (70) perpendicular to the second direction of extension is formed.

36. The method of claim 34 or 35, further comprising substantially uniformly distributing the axes (68, 70) in the second direction of extension.

37. The method of claim 36, further comprising providing a substantially uniform density of axes (68, 70) in the second direction of extension.

38. The method of any of claims 29-37, further comprising substantially uniformly distributing the plurality of first panels (60) in the second direction of extension.

39. The method of claim 38, further comprising providing a substantially uniform density of the plurality of first panels (60) in the second direction of extension.

40. The method of any of claims 27-39, wherein providing a lower flange (46) and an upper flange (48) further comprises, for each flange (46, 48):

forming an open lattice panel (71); and

orienting the panel (71) in the first direction of extension,

wherein the open lattice panel (71) forming the lower flange (46) and the upper flange (48) is formed by a continuous fiber reinforced additive manufacturing process.

41. The method of claim 40, wherein forming a panel (71) for the lower flange (46) and the upper flange (48) further includes: for each of the panels (71), a plurality of axes (72, 74) are formed with respect to a first direction of extension of the panel (71).

42. The method of claim 41, further comprising unevenly distributing the shafts (72, 74) in the first direction of extension.

43. A method according to claim 42, further comprising providing an axle (72, 74) density in the first extension direction in a high load area of the shear web (44) that is greater than an axle (72, 74) density in a low load area of the shear web (44).

44. The method of any of claims 27-43, wherein providing the lower flange (46) and the upper flange (48) further includes forming an extension tab (104) on each of the lower flange (46) and the upper flange (48).

45. The method of claim 44, further comprising forming the extension piece (104) with a widened portion (112).

46. The method of claim 44 or 45, further comprising arranging shafts (64, 66, 68, 70) extending from the lower flange (46) and the upper flange (48) in a fanned configuration adjacent ends of the lower flange (46) and the upper flange (48) including the extension tab (104).

47. The method of claim 27, the method further comprising:

forming the lower flange (46) and the upper flange (48) from a laminated composite construction or a pultruded construction;

forming the web structure (50) from a laminated composite construction; and

the open lattice structure (94, 100) is formed on at least one surface of the lower flange (46), the upper flange (48) and the web structure (50).

48. The method of claim 47, further comprising forming the open lattice structure (94) on opposing first (90) and second (92) surfaces of the web structure (50).

49. The method of claim 47 or 48, further comprising forming the open lattice structure (100) on an outer surface (108) of each of the lower flange (46) and the upper flange (48).

50. A method of manufacturing a wind turbine blade (20), the method comprising:

forming a first blade half (30);

forming a second blade half (32);

forming a shear web (44) according to any one of claims 27-49;

-connecting the shear web (44) to the first blade half (30);

-connecting the second blade half (32) to the first blade half (30); and

the shear web (44) is connected to the second blade half (32).

51. The method of claim 50, wherein forming the first blade half (30) and the second blade half (32) further comprises molding each of the first blade half (30) and the second blade half (32).

52. The method of claim 50 or 51, further comprising:

forming the wind turbine blade (20) into a first blade section (116 a) and a second blade section (116 b) configured to join at a connection interface (118), wherein the first blade section (116 a) and the second blade section (116 b) comprise a first shear web portion (44 a) and a second shear web portion (44 b), wherein at least the web structure (50 a) of the first shear web portion (44 a) and the web structure (50 b) of the second shear web portion (44 b) are configured to be connected to each other in a nested relationship; and

-connecting the first blade section (116 a) and the second blade section (116 b) together at the connection interface (118) such that the arrangement of the shafts (64, 66, 68, 70) in the web structure (50 a) of the first shear web portion (44 a) and the arrangement of the shafts (64, 66, 68, 70) in the web structure (50 b) of the second shear web portion (44 b) are substantially aligned on the connection interface (118).