ADDITIVE MANUFACTURED WING STRUCTURE HAVING A PLURALITY OF CHORDWISE WING SEGMENTS

An airfoil structure for an aircraft includes at least two components mated together adjacently along a chordwise direction. The at least two components extend in the chordwise direction from a front surface to a back surface, the front surface defines a contour of a leading edge of the airfoil structure, and the back surface defines contour of a trailing edge of the airfoil structure. Each of the at least two components includes receiving apertures defined therein at one or more spanwise locations along a spanwise direction, and the receiving apertures at each of the one or more spanwise locations are aligned with each other in the chordwise direction. The airfoil structure also includes a plurality of chordwise reinforcement elements extending through the aligned receiving apertures between the front surface and the back surface.

FIELD

The present disclosure relates generally to an additive manufactured airframe structure and, in particular, to additive manufactured airfoil structures.

BACKGROUND

Additive manufacturing of parts is desirable as it provides the ability to rapidly change out parts and keep the stock of parts low. However, the current technology does not provide for assembling structures from several components without loss in one or more of the mechanical properties of the structure.

BRIEF SUMMARY

In one aspect, an airfoil structure for an aircraft is provided. The airfoil structure includes at least two components mated together adjacently along a chordwise direction. The at least two components extend in the chordwise direction from a front surface to a back surface, the front surface defines a contour of a leading edge of the airfoil structure, and the back surface defines contour of a trailing edge of the airfoil structure. Each of the at least two components includes receiving apertures defined therein at one or more spanwise locations along a spanwise direction, and the receiving apertures at each of the one or more spanwise locations are aligned with each other in the chordwise direction. The airfoil structure also includes a plurality of chordwise reinforcement elements extending through the aligned receiving apertures between the front surface and the back surface.

In another aspect, an airfoil structure for an aircraft is provided. The airfoil structure includes, in sequence along a chordwise direction, a monolithic front component that includes a base joining surface and a front surface, the front surface defining a leading edge of the airfoil structure; a monolithic central component that includes a base surface coupled to the base joining surface and a rear surface opposite the base surface; and a monolithic rear component that includes a rear joining surface coupled to the rear surface.

In another aspect, a method of making an airfoil structure is provided. The method includes mating together at least two components adjacently along a chordwise direction. The at least two components extend in the chordwise direction from a front surface to a back surface, the front surface defines a contour of a leading edge of the airfoil structure, and the back surface defines contour of a trailing edge of the airfoil structure. Each of the at least two components includes receiving apertures defined therein at one or more spanwise locations along a spanwise direction, and the receiving apertures at each of the one or more spanwise locations are aligned with each other in the chordwise direction. The method also includes inserting a plurality of chordwise reinforcement elements through the aligned receiving apertures.

In another aspect, a method of making an airfoil structure is provided. The method includes coupling a base joining surface of a monolithic front component to a base surface of a monolithic central component. The front component includes a front surface that defines a contour of a leading edge of the airfoil structure. The method also includes coupling a rear joining surface of a monolithic rear component to a rear surface of the central component. The front component, the central component, and the rear component are coupled together in a chordwise direction.

DETAILED DESCRIPTION

The term substantially, as used herein, is defined to be essentially conforming to the particular dimension, shape or other word that substantially modifies, such that the component need not be exact. For example, substantially cylindrical means that the object resembles a cylinder, but can have one or more deviations from a true cylinder.

The present disclosure solves the problem of conventional structures built using additive manufacturing being either too weak or heavy for use in desired applications. The present technology can be implemented in vehicles including boats, floating vessels, submersibles, and aircraft. Additionally, the present technology can be implemented with projectiles, ordinance, rockets, missiles, and/or other objects designed to move through air, space, and/or water. The present disclosure uses aircraft as the example, but other structures can be assembled using the technology. Specifically, an airframe can include one or more airframe structures that are formed using one or more assembled airframe components. The subject of the application is the assembled airframe components and airframe structures that are made from a plurality of additive manufactured airframe segments. Other technologies use very expensive materials such as carbon fiber which do not allow for easy development and implementation with standard additive manufacturing materials. The present technology uses additive manufacturing combined with reinforcement elements to provide both the necessary shear strength, tensile strength, and compressive strength.

The present disclosure presents an additive manufactured structure. The additive manufactured structure can include a plurality of additive manufactured components operable to be linked together in one or more assembled directions. Additionally, the additive manufactured structure includes a plurality of reinforcement elements operable to be received in corresponding receiving portions of the plurality of manufactured components and extending through the plurality of manufactured components in direction(s) normal to the one or more assembled directions.

The present disclosure presents reinforcement elements to link a plurality of additive manufactured components together in an assembled configuration. The receiving portion of the plurality of manufactured components is located on an interior of a corresponding one of the plurality of manufactured components. The receiving portion forms a substantially hollow portion for receiving the respective reinforcement elements. The reinforcement elements can be rod shaped and/or tube shaped, and can have any cross-sectional shape, including circular, oval, rectangular, or another shape. The reinforcement elements can be carbon fiber and/or pultruded. In other examples, the reinforcement elements can be fiberglass, E glass, S glass, aramid, metallic, and/or wood.

FIG.1illustrates an isometric view of an example airframe10including a plurality of airframe structures20, such as a wing24, a fuselage26, a horizontal tail28, and/or a vertical tail36. The airframe10may be assembled from a plurality of air frame components22, some or all of which may be additive manufactured. According to at least one example of the present disclosure, one or more of the airframe components22may form additive manufactured airframe segments30. Each of the assembled airframe structures20can include a plurality of additive manufactured airframe segments30. The illustrated airframe segments30can include wing segments32and/or fuselage segments34, for example. As illustrated, the airframe10can be built using these plurality of airframe segments30in an assembled configuration. In the manufacturing of the airframe segments30, a receiving portion of the airframe segments30is formed. The receiving portion is illustrated below with respect to the wing segment32. The receiving portion is located on the interior of the airframe segment30. In at least one example, the receiving portion extends through the airframe segments30. Other airframe components22can also include formers, bulkheads, ailerons, elevators, rudders, stabilizers, spoilers, tabs, slats, and/or ribs.

The example inFIG.1does not include a motive force such as a jet engine or propeller. However, the present technology can be implemented with the desired motive force. Additionally, the present technology can be provided without a motive force such that the airframe10can be configured as a glider.

The present disclosure relates particularly to additive manufactured components22that may be used to form an airfoil structure, such as a wing24, a horizontal tail28, a vertical tail36, or any other airfoil structure that may be used on a fixed wing or rotary aircraft (not shown). Airfoil structures may be described geometrically in terms of a spanwise direction101, extending along a length of the airfoil structure from a root (generally affixed to the fuselage) to a tip (generally a free end), and a chordwise direction103, extending along a width of the airfoil structure from a leading edge (generally facing toward a direction of flight) to a trailing edge opposite the leading edge. For example, in the case of the wing24, the spanwise direction101extends from a root42to a tip44of the wing, and the chordwise direction103extends along a width of the wing from a leading edge46to a trailing edge48. A typical additive manufacturing process uses a 3D printer to deposit or “print” successive thin layers of material, one on top of the other in a stacking direction (often called the “z direction”), to build a component.

Conventionally it is desirable to print airfoil structures by adding the successive layers of material in the spanwise direction of the airfoil structure, that is, to align the z direction of the printer with the spanwise direction101of the component. This is because the geometry of airfoil-shaped structures presents no adequate flat base for 3D printing, apart from a plane normal to the spanwise direction. For example, to print an airfoil-shaped component in the chordwise direction103, one would have to somehow balance and stabilize the tightly curved leading edge46or tapered trailing edge48on the print bed at the beginning of, and throughout, the 3D printing process, which presents enormous difficulties in light of the need to precisely and smoothly form the contours of the airfoil shape for aerodynamic performance. However, in some cases aligning the z direction of the printer with the spanwise direction101of the airfoil structure may not allow additive manufacture of an integral component that encompasses an entire cross-section of the airfoil. For example, if a chordwise dimension of the airfoil structure exceeds about 16 inches, conventional 3D printer beds may not have sufficient area to accommodate the entire cross-section of the airfoil. An inability to print segments of the airfoil structure that include the entire cross-section of the airfoil may reduce the structural strength of the airfoil structure. Known 3D printers with larger beds may be undesirable because they typically are much more expensive, produce less precise builds, and have dramatically increased print times for each component.

Moreover, in some cases there may be a drawback to aligning the stacking direction z with the spanwise direction of an airfoil structure component. During operation of an aircraft, airfoil structures such as wings are subjected to significant torsional loads about an axis parallel to the spanwise direction, which induces significant shear stress in a plane normal to the spanwise direction, as well as significant bending loads about an axis parallel to the chordwise direction, which induces significant tensile stress along the spanwise direction. Additive manufactured components typically are less capable of handling shear stress in the x-y plane (i.e., in planes parallel to the plane of the printer bed), and are less capable of handling tensile stress in the z direction as compared to the x and y directions. This is because the material deposited in a single layer typically bonds together more strongly than material deposited across adjacent layers. In other words, layers of material stacked together can be pulled apart from each other in shear or vertically more easily than a single layer can be pulled apart. Thus, aligning the stacking direction z with the spanwise direction of an airfoil structure component typically orients the least strong shear and tensile directions of the component with the greatest shear and tensile stresses faced by the component.

The present disclosure solves these and other problems in some applications. In some embodiments, an airfoil structure for an aircraft includes at least two components mated together adjacently along a chordwise direction. The at least two components extend in the chordwise direction from a front surface to a back surface, wherein the front surface defines a contour of a leading edge of the airfoil structure and the back surface defines contour of a trailing edge of the airfoil structure. Each of the at least two components may be separately additively manufactured, and thus each component may be a monolithic component. However, because the at least two components are chordwise-adjacent, a cross-section of the resulting airfoil shape is divided among the at least two components. To improve the structural strength and integrity of the airfoil structure, each of the at least two components may include receiving apertures defined therein at one or more spanwise locations along a spanwise direction, and the receiving apertures at each of the one or more spanwise locations are aligned with each other in the chordwise direction. Chordwise reinforcement elements may be inserted through the aligned receiving apertures to add structural strength and stability to the mated components. The receiving apertures may be integrally formed within each component during the additive manufacturing process, improving an ease of manufacture and a structural integrity around the apertures. In some applications, the chordwise reinforcement elements may be configured to compress the mated components together. In some examples, this is achieved by pre-tensioning the chordwise reinforcement elements, bonding them to the components along the receiving apertures, and then releasing the pre-tension, which causes the chordwise reinforcing elements to compress the at least two components together in the chordwise direction. Additionally or alternatively, in certain applications, one or more of the at least two airfoil structure components may be additively manufactured with the stacking direction z of the 3D printer aligned with the chordwise direction, which may better align the direction of greatest strength of the printed component with the greatest shear and tensile stresses faced by the component when the aircraft is in operation.

In order to explain the present disclosure in more detail, the figures illustrate examples of the at least two components mated together along the chordwise direction as including three wing components22. However, as noted above, embodiments of the disclosure may alternatively include two components, four components, or any suitable number of components joined sequentially in the chordwise direction and defining a leading and trailing edge of the airfoil structure. Moreover, the airfoil structure is not limited to a wing. For example, the airfoil structure may be a horizontal tail28, a vertical tail36, or another suitable airfoil structure.

More specifically,FIGS.2-4illustrate the at least two components as, respectively, a front component110, a central component120, and a rear component130, that can be additive manufactured separately and then joined together, sequentially along the chordwise direction103, to form one of the wing segments32. Because the front component110, the central component120, and the rear component130, are each additively manufactured components, each of the front component110, the central component120, and the rear component130is a monolithic, integrally formed structure, which may improve a structural integrity of the wing24and also may reduce a number of component joining steps and equipment (e.g., fasteners, riveting tools) required to build the wing24.

In particular, inFIGS.2-4, each component22is oriented with respect to the z direction (e.g., the stacking direction of a 3D printer) to illustrate the direction in which layers may be added to form the component during the additive manufacturing process.FIGS.5-7illustrate a series of steps in assembling the wing24using the front components, the central components, and the rear components, along with a plurality of reinforcement elements200; andFIGS.8and9illustrate views of portions of the assembled wing24. The reinforcement elements200may also be referred to as a first plurality of reinforcement elements200or as spanwise reinforcement elements200.

With reference toFIG.3, the central component120includes an outer wall126that defines a hollow interior127extending along the spanwise direction101. In some examples, the central component120is built in a stacking direction z generally aligned with the chordwise direction103of the wing. By unconventionally aligning the stacking direction with the chordwise direction of the central component120, shear stress in planes normal to the spanwise direction (caused by wing torsion) occurs primarily in planes other than the x-y plane of the component, and tensile stress in the spanwise direction101(caused by bending of the wing) occurs primarily along the x or y directions rather than the z direction of the component. Thus, a structural performance of the central component120under typical operational loading of the airframe10may be improved by aligning the stacking direction z of the additive manufacturing process with the chordwise direction103. However, examples in which the central component120is additive manufactured with the stacking direction z aligned with the spanwise direction101are also contemplated, as certain other advantages of the disclosure discussed herein may still be obtained.

In addition, the problems inherent in forming an airfoil-shaped component by stacking layers in the chordwise direction103, as discussed above, are overcome by splitting the wing segment32into multiple components along the chordwise direction103. Splitting the wing segment32into multiple chordwise components enables the central component120to be designed with a generally flat base surface122and a generally chordwise-tapered shape extending in the stacking direction z. The generally flat base surface122is printed first on the x-y plane of the 3D printer bed, providing a stable initial series of material layers upon which successive layers of the component can be printed. The base surface122may then be coupled to a separately manufactured, chordwise-adjacent front component110(an example of which is shown inFIG.2) that provides a suitable airfoil shape for the leading edge46of the wing segment32. Although certain advantages may thus be obtained by configuring the base surface122as generally flat, other shapes and contours for base surface122are also contemplated.

The central component120also includes a rear surface124, opposite the base surface122. In some examples, the rear surface124is sized and shaped for coupling to a chordwise-adjacent rear component130(shown inFIG.4) that provides a suitable airfoil shape for the trailing edge48of the wing segment32. Alternatively, the rear surface124itself may be contoured to provide the trailing edge48of the wing segment.

The central component120may also include a plurality of receiving channels129defined in the outer wall126and extending along the spanwise direction101. Each of the receiving channels129may be configured to receive a corresponding reinforcement element200(shown inFIG.5) inserted in the spanwise direction101. In some examples, the receiving channels129are defined along an entire spanwise extent of the central component120. In other examples, the receiving channels129are defined along less than an entire spanwise extent of the central component120.

In some examples, the outer wall126includes reinforced regions128extending along the spanwise direction101and having an increased wall thickness, and the receiving channels129are defined in the reinforced regions128to provide increased structural support for the reinforcement elements. However, examples in which the outer wall126does not include reinforced regions128are also contemplated.

With reference toFIG.2, the front component110also includes an outer wall116that defines a hollow interior117extending along the spanwise direction101. Because the central component120may serve as the primary load-carrying wing component22, or “torque box,” of the wing segment32, the stacking direction material property constraints of additive manufactured components, as discussed above, may be of less importance for the front component110. Accordingly, in some examples, the front component110may be built in a stacking direction z generally aligned with the spanwise direction101of the component. However, examples in which the front component110is additive manufactured in a stacking direction z aligned other than with the spanwise direction101are also contemplated.

As noted above, the front component110is configured to couple in chordwise-adjacent fashion to the central component120to provide a suitable airfoil shape for the leading edge46of the wing segment32. To that end, the front component110includes a base joining surface114configured to couple to the base surface122of the central component120, and a front surface112opposite the base joining surface along the chordwise direction103. For example, the base joining surface114may be configured to mate in a substantially face-to-face relationship with the base surface122. The base surface122and the base joining surface114may be referred to as first and second joining surfaces in some examples. In the illustrated example, the front surface112is printed to have the desired contour of the leading edge46during the additive manufacturing process. Alternatively, the front surface is initially printed to extend at least partially beyond the desired contour, and a finishing process is performed on the initial front surface after additive manufacturing is completed to provide the desired contour of the leading edge46. Examples are also contemplated in which the front component110indirectly provides the leading edge46for the wing segment. For example, the front surface112may be configured to couple to another forward chordwise-adjacent component (not shown) that is in turn contoured to form the leading edge46.

With reference toFIG.4, the rear component130also includes an outer wall136that defines a hollow interior137extending along the spanwise direction101. Because the central component120may serve as the primary load-carrying wing component22, or “torque box,” of the wing segment32, the stacking direction material property constraints of additive manufactured components, as discussed above, may be of less importance for the rear component130. Accordingly, in some examples, the rear component130may be built in a stacking direction z generally aligned with the spanwise direction101of the component. However, examples in which the rear component130is additive manufactured in a stacking direction z aligned other than with the spanwise direction101are also contemplated.

As noted above, the rear component130is configured to couple in chordwise-adjacent fashion to the central component120to provide a suitable airfoil shape for the trailing edge48of the wing segment32. To that end, the rear component130includes a rear joining surface132configured to couple to rear surface124of the central component120, and a back surface134opposite the rear joining surface along the chordwise direction103. For example, the rear joining surface132may include one or more surface portions configured to mate in a substantially face-to-face relationship with one or more surface portions of the rear surface124. In some examples, the rear joining surface132of the rear component130and the rear surface124of the central component120are complementarily shaped to increase a mating surface area of the joint therebetween. For example, in the illustrated example, the rear surface124of the central component120has a wedge shape, and the rear joining surface132has a complementary receiving shape sized and oriented to mate in face-to-face relationship with both surface portions of the wedge shape. Shapes that provide an increased mating surface area may provide an advantage in examples in which the rear joining surface132and the rear surface124are bonded together using an adhesive, for example. Notwithstanding these potential advantages, other shapes are contemplated for the rear joining surface132and the rear surface124. The rear joining surface132and the rear surface124may also be referred to as first and second joining surfaces in some examples.

In the illustrated example, the back surface134is printed to have the desired contour of the trailing edge48during the additive manufacturing process. Alternatively, the back surface is initially printed to extend at least partially beyond the desired contour of the trailing edge, and a finishing process is performed on the initial back surface after additive manufacturing is completed to provide the desired contour of the trailing edge48(shown inFIG.1). Additionally or alternatively, a finishing process is performed on the back surface134after additive manufacturing is completed to provide the desired contour of the trailing edge48. Examples are also contemplated in which the rear component130indirectly provides the trailing edge48for the wing segment. For example, the back surface134may be configured to couple to another rearward chordwise-adjacent component (not shown) that is in turn contoured to form the trailing edge48.

In some examples, forming each wing segment32from a series of chordwise-adjacent, separately additively manufactured wing components22, such as components110,120, and130, facilitates provides advantages over the conventional approach of additively manufacturing wing segments that encompasses an entire chordwise dimension of the wing34. For example, a 3D printer needed to print the separate components110,120, and130may have a smaller printer bed size than a 3D printer needed to print a wing segment that has the entire chordwise dimension of the wing.

FIG.5illustrates an example of two unassembled spanwise-adjacent wing segments32according to at least one example of the present disclosure.FIGS.6-7illustrate steps in assembling the two example spanwise-adjacent wing segments32together. In the example, each wing segment32includes three components22in a chordwise-adjacent arrangement: the central component120, the front component110, and the rear component130. However, as noted above, it is contemplated that one or more wing segments may include only two components22. For example, but without limitation, the front component110may be provided substantially as illustrated, and the central component120may mate to the front component110substantially as shown but also be contoured to provide the trailing edge48. For another example, but without limitation, the rear component130may be provided substantially as illustrated, and the central component120may mate to the rear component130substantially as shown but also be contoured to provide the leading edge46. Likewise, as noted above, it is contemplated that the one or more wing segments may include more than three components. For example, but without limitation, for an airfoil structure having a relatively large airfoil cross-section, one or more of the front component110, the central component120, and the rear component may be subdivided into two separate chordwise-adjacent components joinable at additional complementary mating surfaces similar to the joining surfaces illustrated herein.

Also in the example, like components22in each wing segment32have an identical size and shape, i.e., the central components120in both wing segments32have the same size and shape, the front components110in both wing segments32have the same size and shape, and the rear components130in both wing segments32have the same size and shape. However, it is contemplated that one or more of the front component110, the central component120, or the rear component130may vary in size or shape across wing segments32in a wing design. For example, a wing design may taper in cross-sectional size along the spanwise direction101from the root to the tip of a wing, and each of the front component110, the central component120, and the rear component130may accordingly taper in size along the spanwise direction.

The receiving channels129of each of the central components120are configured to align, along the spanwise direction101, with the corresponding receiving channels129of at least one spanwise-adjacent central component120. InFIG.5, a plurality of reinforcement elements200are oriented for insertion into, and in some cases through, the aligned receiving channels129of the central components120. InFIG.6, the reinforcement elements are inserted completely through the receiving channels129of the central component120of a first wing segment and into the receiving channels129of a spanwise-adjacent second wing segment32. In some examples, the central components of the wing segments32along the span of the wing may be coupled together by sliding the central components120along the reinforcement elements200and into serial spanwise abutment with each other.

InFIGS.5-6, the front component110, the central component120, and the rear component130of each wing segment32are arranged and oriented for coupling together. In other words, the base joining surface114of the front component is oriented for coupling to the base surface122of the central component120, and the rear joining surface132of the rear component130is oriented for coupling to the rear surface124of the central component120. InFIG.7, the front component110and the rear component130of each wing segment32have both been coupled to the corresponding central component120at respective wing-segment joints38. In the illustrated example, the base joining surface114of the front component is coupled in face-to-face relationship with the base surface122of the central component120to form a forward wing-segment joint38, and the rear joining surface132of the rear component130is received by the rear surface124of the central component120to form a rear wing-segment joint38(e.g., the two surfaces of the wedge shape of the rear surface124are coupled in respective face-to-face relationships with the two surfaces of the wedge-receiving shape of the rear joining surface124of the central component120). However, other shapes and orientations are contemplated for the respective joining surfaces that form the wing-segment joints38. In some examples, the joints38are formed by bonding the respective joining surfaces of the front component110, the central component120, and the rear component130. Non-limiting examples of a bonding mechanism include adhesion, a pressure fit, or a friction fit. Additionally or alternatively, the front component110, the central component120, and the rear component130may be affixed to each other using a second plurality of reinforcement elements220extending in the chordwise direction, as discussed above and shown inFIG.17.

AlthoughFIGS.6and7illustrate the spanwise-adjacent central components120being engaged with and slid over the reinforcement elements200prior to the wing-segment joints38between chordwise-adjacent components of each wing segment32being formed, it is also contemplated that one or more of the wing-segment joints38between the chordwise-adjacent components of each wing segment32may be formed prior to the spanwise-adjacent central components120being engaged with and slid over the reinforcement elements200.

FIG.8illustrates an example of a plurality of assembled spanwise-adjacent wing segments32, andFIG.9illustrates a partially transparent view the assembled spanwise-adjacent wing segments32. In the example, four assembled wing segments32have been joined together to form at least a portion of a wing24. For example, the reinforcement elements200may be inserted into the receiving channels129of a first wing segment32, and the first wing segment32may then be slid along the reinforcement elements200in the spanwise direction101to the tip44(or, alternatively, to the root42) of the wing. Each successive wing segment32may be slid along the reinforcement elements200in the spanwise direction101into abutment with the preceding wing segment32at a respective seam40. After assembly is complete, each of the spanwise reinforcement elements200extends within respective aligned sets of the receiving channels129of the spanwise-adjacent central components120.

In some examples, the reinforcement elements200may be pre-tensioned during the insertion within and through the central components120, and the pre-tension may be released after the reinforcement elements200are in their assembly position. As the pre-tensioned reinforcement elements200relax towards their rest state after the release of the pre-tension, the reinforcement elements200tend to compress the spanwise-adjacent central components120(and any chordwise-adjacent wing components110or130bonded to them) together, which may improve a structural integrity and performance of the wing24. However, examples in which the reinforcement elements200are not-pre-tensioned are also contemplated.

As illustrated, the reinforcement elements200are substantially cylindrical. In other examples, the reinforcement elements200can be substantially shaped as a flat bar, angle, hexagonal, channel, tee bar, half round, half oval, and/or chamfer bar. Additionally, the reinforcement elements200can take other shapes suitable for insertion into a complementarily shaped receiving channel129. As illustrated, the reinforcement elements200are in the form of solid rods. In other examples, the reinforcement elements200may be tubular, i.e., hollow inside.

The reinforcement elements200can be formed from different types of materials. In one example, the reinforcement elements200are formed from a high strength material such as carbon fiber. In another example, the reinforcement elements200can be carbon fiber rods. In still another example, the reinforcement elements200can be pultruded rods. In yet another example, the reinforcement elements200can be pultruded carbon fiber rods. In other examples, the reinforcement elements200can be formed from fiberglass, E glass, S glass, aram id, metal, and/or wood. In the illustrated example, there are six different reinforcement elements200. In other examples, there can be any suitable number of reinforcement elements200.

As illustrated, the reinforcement elements200extend continuously through the plurality of wing segments32. Accordingly, the reinforcement elements200can provide additional tensile and compressive strength that is needed for a given wing24. In some examples, the reinforcement elements200are bonded within the receiving channels129. Non-limiting examples of a bonding mechanism include adhesion, a pressure fit, or a friction fit. For example, the reinforcement elements200can be bonded along substantially an entire length of the receiving channels129. In other examples, the reinforcement elements200may be bonded along discrete portions of the receiving channels129. For example, as illustrated inFIG.9, the portions131of the receiving channels129along which the reinforcement elements200are bonded may be adjacent to, and extend through, the seams40. In addition, the portions131of the receiving channels129along which the reinforcement elements200are bonded may be adjacent to the wing tip44. In other examples, the reinforcement elements200may be bonded along any suitable portion of the receiving channels129.

FIG.10illustrates an isometric view of an interleaved configuration of a wing24according to at least one example of the present disclosure. In this context, the term “interleaved” means that the seams40between central components120are not aligned with at least one of (i) the seams40between front components110, or (ii) the seams40between rear components130. As a result, as seen inFIG.10, each of the wing segments32has a spanwise extent that varies between the central component120and at least one of the front components110or the rear components130. In some examples, such interleaving improves a load distribution through the wing segments32along the chordwise direction103, as compared to an arrangement with aligned chordwise-aligned seams40as shown inFIG.8.

In the illustrated example, the interleaving is arranged such that the seam40between each pair of spanwise-adjacent front components110is adjacent to a mid-span point of a corresponding central component120. In this configuration, the front components110adjacent to the wing tip44and to the wing root46, respectively, have a span that is half the span of the other front components110. However, other interleaving arrangements are also contemplated. In the illustrated example, the interleaving is for the rear components130is arranged to match the interleaving for the front components110. However, non-matching interleaving of the front and rear components is also contemplated.

FIG.11illustrates another example of the front component110, the central component120, and the rear component130.FIGS.12-15illustrate various stages of coupling the example components ofFIG.11together. The wing components are generally as described above, but also include complementary mating features140on each pair of chordwise-adjacent mating surfaces.

For example, as shown inFIG.11, the base joining surface114of the front component110includes one of the mating features140in the form of a dovetail slot142depending therefrom and extending in the spanwise direction101. The central component120includes a complementary one of the mating features140in the form of a protrusion144extending from the base surface122and extending in the spanwise direction101, and the protrusion144is sized and shaped to be slidably received in the dovetail slot142. The reverse arrangement is also contemplated, in which the dovetail slot142depends from the base surface122of the central component120and the complementary protrusion144extends from the base joining surface114of the front component110. In addition, slot and protrusion shapes other than dovetail are also contemplated.

In some examples, the presence of the mating feature140on the base surface122may reduce an ease of forming the central component120by additive manufacturing with the stacking direction z aligned with the chordwise direction103(seeFIG.3). However, other advantages of the disclosure, such as but not limited to ease-of-assembly advantages provided by the mating features140and, optionally, structural advantages provided by a second plurality of reinforcement elements220extending chordwise, as discussed above and shown inFIG.17, may still be obtained in examples where the central component120is formed other than by additive manufacturing with the stacking direction z aligned with the chordwise direction103.

Similarly in the illustrated example, as shown inFIG.11, the rear joining surface132of the rear component130includes a pair of dovetail slots142depending therefrom (one on each of the surfaces of the wedge-receiving shape) and extending in the spanwise direction101. The central component120includes a corresponding pair of protrusions144extending from the rear surface124and extending in the spanwise direction101, and the protrusions144are sized and shaped to be slidably received in the corresponding dovetail slots142. The reverse arrangement is also contemplated, in which the pair of dovetail slots142depend from the rear surface124of the central component120and the complementary protrusions144extend from the rear joining surface132of the rear component130. Although two slots and two corresponding protrusions are illustrated, other numbers of slots and corresponding protrusions are also contemplated. In addition, complementary shapes other than dovetail slots and protrusions are also contemplated.

InFIG.12, the front component110and the rear component130are illustrated as in position for an initiation of sliding engagement, in the spanwise direction101, of the their respective mating features140with the front and rear mating features140the central component120. InFIG.13, the mating features140of the front component110and the rear component130are illustrated as engaged with, and slid a first distance in the spanwise direction101along, the mating features140of the central component120. InFIG.14, the mating features140of the front component110and the rear component130are illustrated as engaged with, and slid a second distance in the spanwise direction101along, the mating features140of the central component120. InFIG.15, the mating features140of the front component110and the rear component130are illustrated as substantially completely engaged with the mating features140of the central component120, such that the front component110and the central component120form a first wing-segment joint38, the central component120and the rear component130form a second wing-segment joint38, and the front component110, the central component120, and the rear component130are coupled together to form the wing segment32. Forming the joints38may further include bonding cooperating pairs of mating features140together, and additionally or alternatively may include bonding other portions of mating surfaces114and122together or other portions of mating surfaces124and132together. Non-limiting examples of a bonding mechanism include adhesion, a pressure fit, or a friction fit.

AlthoughFIGS.12-15illustrate the mating features140of the front component110and the rear component130as being slid simultaneously, and in opposite spanwise directions, into engagement with the mating features140of the central component120, this is solely for purposes of illustration. Examples in which the mating features140of the front component110and the rear component130are slid non-simultaneously, and/or in a same spanwise direction, into engagement with the mating features140of the central component120are also contemplated. Moreover, although the illustration shows the wing-segment joints38between the chordwise-adjacent components of each wing segment32being formed prior to the central component120being engaged with and slid over the reinforcement elements200(shown inFIG.7), it is also contemplated that the central component120may be engaged with and slid over the reinforcement elements200prior to the wing-segment joints38being formed.

FIG.16illustrates another example of the front component110, the central component120, and the rear component130.FIGS.17-20illustrate various stages of coupling the example components ofFIG.16together. The wing components110,120,130are generally as described above, but also include receiving apertures149defined therein. The receiving apertures149are sized and oriented to receive a second plurality of reinforcement elements220therethrough to facilitate coupling together and reinforcing the wing components110,120,130. The second plurality of reinforcement elements220may also be referred to as chordwise reinforcement elements220, and may be made from the same materials and in the same shapes as discussed above with respect to the spanwise reinforcement elements200. Although the illustrated example does not show the mating features140shown inFIGS.11-15, it is contemplated that the mating features140substantially as described above may also be included in combination with the receiving apertures149and the chordwise reinforcement elements220.

In the illustrated example, the receiving apertures149are positioned on each wing component110,120,130at two spanwise locations along the spanwise direction101. However, it is also contemplated that the receiving apertures149could be positioned at one spanwise location along each component, or at more than two spanwise locations along each component. The receiving apertures149at each spanwise location are configured to align with each other in the chordwise direction103when the front component110, the central component120, and the rear component130are positioned for coupling into the wing segment32. The alignment of the receiving apertures149at each spanwise location facilitates receiving the chordwise reinforcement elements220through the coupled wing components.

InFIG.17, the front component110, the central component120, and the rear component130are illustrated as in position for an initiation of sliding engagement, in the chordwise direction103, of their aligned respective receiving apertures149by the chordwise reinforcement elements220. In the illustrated example, the wing components110,120,130are configured for initial insertion of the chordwise reinforcement elements220through the back surface134of the rear component. More specifically, the central component120and the rear component130each include two aligned receiving apertures149along each of the spanwise locations, and the front component110includes only one receiving aperture149at each of the spanwise locations. This is to facilitate a sliding insertion of the chordwise reinforcement elements220through, first, the receiving apertures149defined in the back surface134of the rear component130, second, through the receiving apertures149defined in the rear joining surface132of the rear component130, and third, through the receiving apertures149defined in the rear surface124of the central component120, as illustrated inFIG.18; fourth, through the receiving apertures149defined in the base surface122of the central component120, as illustrated inFIG.19; and fifth, through the receiving apertures149defined in the base joining surface114of the front component110, as illustrated inFIG.20. In the illustrated example, no receiving apertures149are defined in the front surface112of the front component110, as the chordwise reinforcement elements220are sized not to extend into or through the front surface112. Instead, first ends222of the chordwise reinforcement elements220are covered by the front surface112. However, it is also contemplated that receiving apertures149could also be defined in the front surface112. For example, the wing components110,120,130could be configured for initial insertion of the chordwise reinforcement elements220through the front surface112of the front component, and then in sequence through the other components in the opposite chordwise direction as that illustrated inFIGS.17-20. In that embodiment, second ends224of the chordwise reinforcement elements220are covered by the back surface134after insertion is complete. Likewise, it is also contemplated that the chordwise reinforcement elements220could first be inserted through the receiving apertures of the middle wing component120, such that the first ends222of the inserted chordwise reinforcement elements220extend outside the middle component120forward along the chordwise direction103and the second ends224of the inserted chordwise reinforcement elements220extend outside the middle component120backward along the chordwise direction103. Then, the receiving apertures149of the front wing component110can be slid over the first ends222, and the receiving apertures149of the rear wing component130can be slid over the second ends224, in order to mate the wing components110,120, and130together. In that embodiment, the first ends222may be covered by the front surface112and the second ends224may also be covered by the back surface134when the wing components are mated together.

InFIG.20, the chordwise reinforcement elements220are substantially engaged with the receiving apertures149in the front component110, the central component120, and the rear component130, such that the front component110and the central component120form the first wing-segment joint38, the central component120and the rear component130form the second wing-segment joint38, and the front component110, the central component120, and the rear component130are coupled together to form the wing segment32. The chordwise reinforcement elements220may be bonded within one or more of the receiving apertures149to reinforce the joints38. Forming the joints38may further include bonding portions of mating surfaces114and122together or portions of mating surfaces124and132together, and additionally or alternatively may include bonding cooperating pairs of mating features140together as described above with respect toFIG.15. Non-limiting examples of a bonding mechanism include adhesion, a pressure fit, or a friction fit.

In some examples, similar to the use of pre-tension described above with respect to the spanwise reinforcement elements200, the chordwise reinforcement elements220may be pre-tensioned during the insertion within and through the front component110, the central component120, and the rear component130, and while the chordwise reinforcement elements are bonded within the receiving apertures149. The pre-tension may be released after the chordwise reinforcement elements220are in their assembly position (for example, after an adhesive used for the bonding has cured). As the pre-tensioned chordwise reinforcement elements220relax towards their rest state after the release of the pre-tension, the chordwise reinforcement elements220tend to compress the chordwise-adjacent front component110, central component120, and rear component130together, which may improve a structural integrity and performance of the wing24. However, examples in which the chordwise reinforcement elements220are not-pre-tensioned are also contemplated.

In the illustrated example, a location of each of the receiving apertures149along a wing thickness direction105differs from a location of each of the receiving channels129along the wing thickness direction105by an offset distance150. The offset distance150in the wing thickness direction is sufficient to avoid interference between the chordwise reinforcement elements220and the spanwise reinforcement elements200. In other words, the offset distance150enables both the chordwise reinforcement elements220and the spanwise reinforcement elements200to be inserted through the wing components110,120,130and into their respective assembled positions without the chordwise reinforcement elements220and the spanwise reinforcement elements200physically blocking each other from insertion and final placement. As illustrated, one or more receiving channels129may be spaced from the receiving apertures149by the offset distance150in a first direction (e.g., “above”), while one or more other receiving channels129may be spaced from the receiving apertures149by the offset distance150in an opposite second direction (e.g., “below”).

In some applications, the chordwise reinforcement elements220and the spanwise reinforcement elements200cooperate to advantageously improve a structural performance of the wing24under bending and torsional loads. This advantage may be obtained in addition to the component bonding or structural advantages obtained by using either the spanwise reinforcement elements200or the chordwise reinforcement elements220in an absence of the other. Moreover, this advantage may be obtained in addition to, or in an absence of, the structural advantages that may be provided by additively manufacturing the central component120with the stacking direction z aligned with the chordwise direction103.

In some examples, the offset distance150is selected to be as small as practically possible while still satisfying the avoidance of interference constraint, as the smaller offset distance150may tend to improve a capability of the wing24to withstand certain bending and torsional loads. In some such examples, one or more of the chordwise reinforcement elements220may come into contact with one or more of the spanwise reinforcement elements200when the wing24is subjected to bending or torsional loads, which may, for example, tend to reduce a deformation of the wing24under such loads.

AlthoughFIGS.16-20illustrate the insertion of the chordwise reinforcement elements220prior to the insertion of the spanwise reinforcement elements200between spanwise-adjacent wing segments32(as described with respect toFIGS.5-9), it is also contemplated that the insertion of one or more of the chordwise reinforcement elements220could occur after the insertion of the spanwise reinforcement elements200between the spanwise-adjacent wing segments32.

FIGS.21and22illustrate an example of the wing24including the chordwise reinforcement elements220and one or more control surfaces300coupled to the wing24. More specifically,FIG.21illustrates the control surfaces300in a closed or inactivated position, andFIG.22illustrates the control surfaces300in an open or activated position. For example, the one or more control surfaces300include an aileron301and a flap302. However, other control surfaces or combinations of control surfaces are also contemplated. Each control surface may be mounted on one or more wing segments32.

In the example, the receiving apertures149of the wing segments32to which the control surfaces300are mounted are positioned under the control surfaces300when the control surfaces are in the closed or deactivated position. The chordwise reinforcement elements220may be installed in these wing segments32prior to coupling the control surfaces300to the wing segments32. Alternatively, the chordwise reinforcement elements220may be installed after coupling the control surfaces300to the wing segments, by holding the control surfaces in the open or activated position during installation of the chordwise reinforcement elements220. It is also contemplated that one or more of the receiving apertures149of the wing segments32to which the control surfaces300are mounted may be offset in the spanwise direction101from the control surface, such that installation of the chordwise reinforcement elements220in those apertures is not affected by the presence or absence of the control surfaces300.

FIG.23is a flow diagram of an example method2300of making an airfoil structure for an aircraft. Method2300may include mating together at least two components adjacently along a chordwise direction (step2304). As discussed above, the at least two components extend in the chordwise direction from a front surface to a back surface, the front surface defines a contour of a leading edge of the airfoil structure, and the back surface defines contour of a trailing edge of the airfoil structure. Each of the at least two components includes receiving apertures defined therein at one or more spanwise locations along a spanwise direction, and the receiving apertures at each of the one or more spanwise locations are aligned with each other in the chordwise direction. Method2300may further includes inserting a plurality of chordwise reinforcement elements through the aligned receiving apertures (step2308).

In some examples, method2300may also include configuring the plurality of chordwise reinforcement elements to exert a compressive force in the chordwise direction on the at least two components. The configuring step may include, for example but not by way of limitation, pre-tensioning the chordwise reinforcement elements and, subsequent to the step of inserting the plurality of chordwise reinforcement elements, releasing the pre-tension. For example, the chordwise reinforcement elements in the pre-tensioned state may be bonded within the receiving apertures.

In some examples, a first component of the at least two components includes an outer wall that defines a hollow interior extending along the spanwise direction, and the outer wall defines a plurality of receiving channels. Method2300may further include inserting a plurality of spanwise reinforcement elements through the receiving channels of the first component. Moreover, method2300may include mating at least two additional components together adjacently along the chordwise direction, and coupling a first additional component of the at least two additional components adjacent, along the spanwise direction, to the first component. The first additional component may also include an outer wall that defines a hollow interior extending along the spanwise direction, and the outer wall of the first additional component may likewise define a plurality of receiving channels. Method2300additionally may include inserting the spanwise reinforcement elements through respective aligned sets of the receiving channels of the first component and the first additional component.

In some examples, the step of mating together the at least two components includes mating a first joining surface of a monolithic front component to a second joining surface of a monolithic second component, and the monolithic front component includes the front surface. In some such examples, the step of mating the first joining surface and the second joining surface includes mating the first joining surface and the second joining surface in a substantially face-to-face relationship. Moreover, in some such examples, the step of mating the first joining surface and the second joining surface includes mating one or more surface portions of the second joining surface in a substantially face-to-face relationship with one or more surface portions of the first joining surface. Also, in some such examples, the step of mating the first joining surface and the second joining surface includes mating complementary mating features of the second joining surface and the first joining surface. For example, the step of mating the complementary mating features may include mating together a slot defined in one of the first joining surface and the second joining surface and a complementary protrusion defined in the other of the first joining surface and the second joining surface.

In some examples, the step of mating together the at least two components may include coupling a base joining surface of a monolithic front component to a base surface of a monolithic central component, wherein the front component includes the front surface, and coupling a rear joining surface of a monolithic rear component to a rear surface of the central component, wherein the rear component includes the back surface.

In some examples, the step of inserting the plurality of chordwise reinforcement elements further includes inserting the plurality of chordwise reinforcement elements through at least one of the front surface and the back surface. Alternatively, in some examples, the step of inserting the plurality of chordwise reinforcement elements includes inserting the plurality of chordwise reinforcement elements through the receiving apertures of a middle component of the at least two components, such that first ends of the inserted chordwise reinforcement elements extend outside the middle component forward along the chordwise direction and second ends of the inserted chordwise reinforcement elements extend outside the middle component backward along the chordwise direction; sliding one or more of the receiving apertures of a front component of the at least two components over the first ends of the inserted chordwise reinforcement elements; and sliding one or more of the receiving apertures of a rear component of the at least two components over the second ends of the inserted chordwise reinforcement elements, such that the first ends are covered by the front surface and the second ends are covered by the back surface when the at least two components are mated together.

FIG.24is a flow diagram of an example method2400of making an airfoil structure for an aircraft. Method2400may include coupling a base joining surface of a monolithic front component, such as the base joining surface114of the additively manufactured front component110, to a base surface of a monolithic central component, such as the base surface122of the additively manufactured central component (step2404). The front component may include a front surface, such as the front surface112, that defines a contour of a leading edge of the wing. Method2400may also include coupling a rear joining surface of a monolithic rear component, such as the rear joining surface132of the additively manufactured rear component130, to a rear surface of the central component, wherein the front component, the central component, and the rear component are coupled together in a chordwise direction (step2408).

In some examples, step2404may include mating the base surface and the base joining surface in a substantially face-to-face relationship. Additionally or alternatively, step2408may include mating one or more surface portions of the rear joining surface, such as the two halves of the wedge-receiving-shaped rear joining surface132as shown inFIG.5, in a substantially face-to-face relationship with one or more surface portions of the rear surface, such as the two halves of the wedge-shaped rear surface124as shown inFIG.5.

In some examples, step2404may include coupling complementary mating features of the base surface and the base joining surface, or step2408may include coupling complementary mating features of the rear surface and the rear joining surface, as described with respect toFIGS.11-15. In either case, the step of coupling the complementary mating features may include sliding a protrusion defined in one of the surfaces into a complementary slot defined in the other of the surfaces.

The method2400may include additional or alternative steps. For example, method2400may include additively manufacturing the central component in a stacking direction generally aligned with the chordwise direction, and may also include additively manufacturing at least one of the front component and the rear component in a stacking direction generally aligned with a spanwise direction of the wing.

For another example, the method2400may include coupling a second front component110, a second central component120, and a second rear component130adjacent, along the spanwise direction101, to the first front component110, the first central component120, and the first rear component130. The components may be interleaved, for example as shown inFIG.10. Additionally or alternatively, the first and second central components120may each include the outer wall126that defines the hollow interior127extending along the spanwise direction101, the outer wall may define a plurality of receiving channels129, and the method may further include inserting each of the plurality of spanwise reinforcement elements200within respective aligned sets of the receiving channels129of the first and second central components120.

For another example, the front component, the central component, and the rear component may include receiving apertures, such as receiving apertures149, at one or more spanwise locations along the spanwise direction101, the receiving apertures at each of the one or more spanwise locations may be aligned with each other in the chordwise direction103, and the method may further include inserting the plurality of chordwise reinforcement elements220through the aligned receiving apertures. In some such examples, the central component120may include the outer wall126that defines the hollow interior127extending along the spanwise direction101, the outer wall may define the plurality of receiving channels129, and the method may further include inserting the plurality of spanwise reinforcement elements200within the receiving channels of the central component. Further, the method may include positioning each of the receiving apertures149along the wing thickness direction105, and positioning each of the receiving channels129along the wing thickness direction at the offset distance150sufficient to avoid interference between the chordwise reinforcement elements220and the spanwise reinforcement elements200.

While preferred examples of the present inventive concept have been shown and described herein, it will be obvious to those skilled in the art that such examples are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the disclosure. For example, reference to an element or method step in one example does not preclude the use of the element or method step in other examples that may include different combinations of elements or method steps disclosed herein. It should be understood that various alternatives to the examples of the disclosure described herein can be employed in practicing the disclosure. It is intended that the following claims define the scope of the disclosure and that methods and structures within the scope of these claims and their equivalents be covered thereby.