Adaptation structure

Abstract

The present invention relates to a deformable aerospace structure, comprising a first layer and a second layer spaced apart from the first layer and defining a space between the first layer and the second layer. The space comprises one or more reinforcing elements extending between the first layer and the second layer. An end or portion of the reinforcing element proximate to the first layer is connected to the first layer, and an end or portion of the reinforcing element proximate to the second layer is movable relative to an end or portion of an adjacent reinforcing element proximate to the second layer.

Description

Technical Field

[0001] The present invention relates particularly, but not exclusively, to an aerodynamic structure which is able to adapt or change shape and thereby provide variable aerodynamic performance. Background Art

[0002] Conventional movable aerodynamic structures used on aircraft include an aerodynamic structure mounted to the aircraft wing, fuselage or engine (etc) by means of a hinge arrangement. The movable structure can then be rotated about the hinge to change the overall aerodynamic performance.

[0003] The movable structures on an aircraft include flaps, ailerons, spoilers, tail planes and various other components that are arranged to direct or control the airflow over the aircraft structure when in use. As an example, the aileron is coupled to the main wing structure by means of a hinge arrangement, thereby allowing the aileron to rotate about a pivot to change the flow direction of the air.

[0004] Actuators (such as electric motors, hydraulic pumps, worm gears, etc.) are used to pivot and move the movable structure about hinges, thereby changing the aerodynamic performance and characteristics of the structure. This allows the flight of the aircraft to be controlled by the movement of the structure.

[0005] For example, aircraft flaps are typically mounted to the trailing edge of a wing by means of a series of hinges positioned along the length of the wing. The flaps are coupled to a series of actuators that, when activated, rotate the flaps, thereby changing the aerodynamic properties of the wing and increasing lift. This arrangement has been used in aircraft design for decades and is robust, reliable, and generally provides adequate aerodynamic performance.

[0006] However, the present inventors have identified an alternative approach to movable aerodynamic structures which provides a structure having a continuous surface which can be adapted in shape to change the aerodynamic performance of the component. The present invention provides a highly adaptable surface without complex internal structures or actuation means, thereby additionally improving reliability and providing a low maintenance solution, which is very important in allowing economical operation of aircraft. Summary of the invention

[0007] Various aspects of the invention are set out in the accompanying claims.

[0008] From a first aspect, a deformable aerospace structure is provided, the structure comprising a first layer and a second layer spaced apart from the first layer, the structure defining a space between the first layer and the second layer, the space comprising one or more reinforcing elements extending between the first layer and the second layer, wherein an end or portion of the reinforcing element proximate the first layer is connected to the first layer, and an end or portion of the reinforcing element proximate the second layer is movable relative to an end or portion of an adjacent reinforcing element proximate the second layer.

[0009] By allowing the points at which the reinforcing elements intersect the second layer to be movable relative to each other, a structure is provided that is flexible and can deform while maintaining a smooth continuous surface on the opposite side of the structure (e.g., the surface facing the airflow). The reinforcing elements (in combination with the manner in which they are coupled or connected to each of the first and second layers) advantageously provide for the desired level of structural strength to be provided while allowing the structure to flex when actuated with a suitable actuator.

[0010] The term "deformable" refers to a structure that is capable of changing shape, particularly bending or flexing, to form a generally curved, concave or convex shape.

[0011] The reinforcing element may be any suitable member and may for example be a plurality of discrete and separate elements extending between the two layers.The elements may be arranged at an angle of less than 90 degrees relative to the two surfaces.

[0012] The elements may be arranged at the same angle or at different angles to provide different properties along the structure. Advantageously, the reinforcing element may be in the form of a plurality of adjacent members each alternating in direction and extending from a first layer to a second layer.

[0013] Alternatively, the reinforcing member may be in the form of a continuous member configured to alternate between the first layer and the second layer along its length. Thus, instead of a plurality of separate elements, a single element may be formed, for example corrugated and located between the two layers. This reduces the number of connections and simplifies construction and manufacture by minimizing the number of components.

[0014] The second layer may advantageously be in the form of one or more elastic elements connecting adjacent reinforcing elements together. The elastic elements may then allow relative movement of adjacent reinforcing elements at the second layer. As described above, relative movement of these points allows the structure to bend.

[0015] For example, the resilient element may be in the form of an elastic or metal spring.

[0016] Advantageously, the second layer may be formed by a continuous elastomeric layer which encapsulates the ends or portions of the reinforcing elements close to the continuous elastomeric layer. Thus, the ends of each of the reinforcing elements (or the portions of the reinforcing elements which are arranged in a corrugated manner) are fixed within the elastomeric layer. Due to the elastomeric properties, not only are the reinforcing elements fixed, but due to the flexibility of the material, movement is also advantageously allowed.

[0017] At the end of the reinforcing elements near the first layer, each adjacent element may be connected to the inner surface of the first layer at a common point or along a common line (ie, at the same location). This provides a V or apex structure that provides rigidity and strength to the first layer and reinforcing layer.

[0018] Thus, providing differences in the way in which adjacent ends of each reinforcing element are connected together results in different stiffnesses on each side of the structure; i.e., the first layer has greater stiffness than the second layer. Specifically, the stiffness between adjacent points at which the reinforcing elements are connected to the first layer may be greater than the stiffness between adjacent points at which the reinforcing elements are connected to the second layer.

[0019] In aerospace applications, the first layer may include an outer surface facing the airflow and an inner surface facing the reinforcing element. The outer surface facing the airflow may then become part of a continuous aerodynamic surface such as a spoiler, a flap, or the like.

[0020] The structure may be formed from any suitable combination of materials whilst maintaining the stiffness requirements described above. For example, the first layer and the reinforcing element may be formed from carbon fibre reinforced plastic or aluminium material and the second layer may be formed from a continuous rubber or silicone elastomer layer.

[0021] Advantageously, the reinforcing element may be in the form of a corrugated member alternating between the first and second layers along its length and defining a plurality of generally V-shaped sections. The one or more V-shaped sections may comprise a supplementary reinforcing member arranged perpendicularly relative to the first and second layers and having a first end extending into the elastomeric layer forming the second layer and a second end extending into the elastomeric material arranged in the base of the V-shaped section adjacent the first layer. Such an arrangement provides enhanced stiffness within the structure.

[0022] From another aspect, a deformable fluid guiding structure is provided, which includes a first layer and a supporting layer separated from the first layer and defining a space between the first layer and the supporting layer, the space including one or more reinforcing elements extending between the first layer and the supporting layer, wherein an end or portion of the reinforcing element near the first layer is connected to the first layer, and an end or portion of the reinforcing element near the supporting layer is encapsulated in an elastomer layer.

[0023] Advantageously, the Young's modulus of elasticity (E) of the elastomeric layer may be between 80 and 120 MPa, between 90 and 110 MPa, or greater than 100 MPa.

[0024] From yet another aspect, a deformable structure for an aircraft component is provided, the structure comprising a first layer facing an airflow and an opposing second layer, the structure defining a space between the first layer and the second layer, wherein the elastic modulus of the first layer facing the airflow is greater than the elastic modulus of the second layer.

[0025] Advantageously, the space includes a reinforcing or supporting layer, such as a corrugated metal or carbon fiber layer, which transfers shear loads between the layer facing the airflow and the second layer. This three-layer arrangement advantageously allows the structure to change shape while allowing the loads caused by the air impinging on the structure to be transferred to the second layer.

[0026] The reinforcing layer itself may be a continuous layer or material having an intermediate elastic modulus between the layer facing the airflow and the second layer. In practice, the laminate structure provides each of the three (or more) layers with a different elastic modulus (decreasing from the airflow side to the second inner side (i.e., the interior for the aircraft structure)).

[0027] Where rubber is used for the second layer, the material properties allow this layer to stretch. The relative thickness of each of these layers may be appropriately selected to accommodate the expected loads and the amount of bending required for the structure.

[0028] Viewed from a further aspect there is provided an aircraft, aircraft engine or wind turbine blade comprising a deformable aerospace structure as described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Various aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0030] Figure 1A and Figure 1B A schematic diagram showing an example movable structure of an aircraft wing;

[0031] Figure 2 shows a cross section through a structure according to the invention described herein;

[0032] Figure 3 The flap and spoiler arrangement is shown in the flap-undeployed state;

[0033] Figure 4 The flap and spoiler arrangement is shown in the flap deployed state;

[0034] Figure 5 shows a force diagram of the structure described herein;

[0035] Figure 6 shows a cross section through a prototype arrangement of the adapting structures described herein; and

[0036] Fig. 7A and Figure 7B Two alternative arrangements of the invention described herein are shown.

[0037] Although the present invention is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and described in detail herein. However, it should be understood that the attached drawings and detailed description are not intended to limit the present invention to the specific forms disclosed, but the present invention covers all modifications, equivalent forms and alternative forms that fall within the spirit and scope of the claimed invention. The words "including", "comprising" and similar words used in this specification should not be interpreted in an exclusive or exhaustive sense. In other words, they mean "including but not limited to".

[0038] It will be appreciated that the features of the various aspects of the invention described herein may be used conveniently and interchangeably in any suitable combination.It will also be appreciated that the invention encompasses not only individual embodiments but also combinations of embodiments that have been discussed herein. DETAILED DESCRIPTION

[0039] The present invention relates to a deformable or morphable structure with an aerodynamic profile. This may include, but is not limited to, flaps, trailing edges, leading edges, spoilers, air inlets, etc. Specifically, the present invention provides a structure in which a minimum number of actuators is desired and, importantly, no hinges are present.

[0040] The structure described herein provides a deformable aerospace structure that advantageously:

[0041] - can transfer loads (no buckling or large deformations are acceptable when loaded under aerodynamic or structural loads);

[0042] - will not fail due to high internal stresses (primarily caused by bending stresses when forced into the desired shape); and

[0043] - is flexible (can be deformed into desired shape. Large deformation is required under actuation load)

[0044] Currently there is no suitable solution that can meet these requirements.

[0045] The invention described herein provides an arrangement in which elements and materials having significant differences in stiffness in the axial direction are combined in a structure such that when the structure deforms / bends, the bending stiffness of the entire structure is increased while the maximum stress in the elements is maintained at an acceptable level.

[0046] The present invention will now be described in detail with reference to the accompanying drawings.

[0047] Figure 1A and Figure 1B is a schematic end view of an aircraft wing 1 viewed in cross section towards the aircraft fuselage. The wing comprises a leading edge 2 and a trailing edge 3. Figure 1 shows an example of a movable structure on a conventional aircraft. The structure shown is a flap 4, which is movable about a pivot (not shown) near the trailing edge of the main wing box 5. Figure 1B Arrow A in shows how the flap can be moved about a pivot. The movement causes the distal portion of the flap to move in an arc from the pivot, which in the case of a flap causes the airflow to change direction (see arrow B) and generate more lift.

[0048] Figure 1A and Figure 1B Represents only 1 position of a movable component on an aircraft structure. Other examples include flaps, empennages, tail rudders, air inlets, spoilers, and even landing gear doors. It will be appreciated that the arrangements and methods described herein may be applied to any articulated arrangement of an aircraft structure.

[0049] An example of the invention described herein will now be provided with reference to one of these movable components, namely a wing spoiler.

[0050] exist Figure 1A and Figure 1B The location of a typical wing spoiler is shown in the figure with reference numeral S. Spoilers can provide a variety of functions. For example, spoilers can be rotated in a vertical direction to increase drag when landing or change the aerodynamic profile to slow down the aircraft in flight. Spoilers operate by rotating the spoiler about a pivot located at its upstream edge, with its trailing edge entering and disturbing the airflow to cause the desired drag.

[0051] In another arrangement, the spoiler can be used to bridge the Figure 1A and Figure 1B The gap formed when the flaps are deployed or activated as shown in .

[0052] like Figure 1B As shown, flaps 4 have been deployed to increase the lift generated by the wing. Figure 1B As shown, when the flap is deployed and rotated away from the wing box, a gap 6 is generated at the trailing edge of the wing box. Such a gap is usually undesirable because it is not conducive to efficient airflow over the wing surface. To solve this problem, a spoiler S can be arranged so as to extend over a portion of the gap to improve efficiency.

[0053] However, due to the way the flaps rotate and the flat structure of the spoiler, there is always an unwanted gap along the trailing edge of the wing box. The invention described herein solves this problem and provides a unique uninterrupted aerodynamic surface that can be easily changed in shape to provide a continuous aerodynamic surface.

[0054] Reference Figure 2 Explain the composition of the structure according to the present invention described herein, Figure 2 is a cross section through the structure.

[0055] The adaptive or dynamic structure 7 comprises an upper or outer first layer 8 and an opposite lower or second layer 9. A gap or space h is defined between the two surfaces or layers. The upper layer 8 is the layer facing the air and has an upper outer surface against which the air flows in flight. It is this surface that receives the air pressure and therefore the associated forces.

[0056] In the example shown, a wave-shaped or corrugated reinforcing or supporting member 10 is positioned between the two layers. Figure 2 As shown, the layers are arranged in a generally V-shaped cross-section, with opposite vertices of the V extending to the first layer and the second layer.

[0057] The precise geometry of the corrugated member 10 will depend on the specific application of the structure, including the angle, height and thickness of the V-shaped cross section. The material used may also be adapted depending on the structural requirements of the component.

[0058] Similarly, the materials used to form the first and second layers may be selected based on the anticipated forces and desired deflections.

[0059] Importantly, at the points where the corrugated reinforcing element intersects the first layer, the reinforcing element is connected or bonded to the inner surface of the first layer (reference numeral 11). Depending on the materials used, this may be done by adhesive, co-curing or welding. Thus, the reinforcing element is securely fixed or connected to the top of the reinforcing element at each vertex (or subset of vertices).

[0060] The first upper surface or layer may be carbon fiber reinforced plastic (CFRP) or a metal such as aluminum or titanium. In the example of a spoiler, it may be, for example, an aluminum layer having a thickness between 1 and 1.6 mm. Similarly, the reinforcing element may be formed of CFRP or aluminum having a thickness between 0.6 and 1.2 mm.

[0061] exist Figure 2 In the example shown, the opposite vertices of the reinforcing element extend into the second layer 9, as shown in FIG. Figure 2 Thus, the ends of the reinforcing elements extending to the second layer may be enclosed within the second layer, rather than being bonded or connected to the layer (eg by means of welding) as described above with respect to the first layer.

[0062] Importantly, Figure 2 The second layer shown in is an elastomeric material, such as silicone or rubber, having a Young's modulus of elasticity of about 100 MPa (with a thickness of 6 mm). Thus, the ends or parts of the corrugated reinforcing element 10 are completely enclosed in the flexible (or semi-flexible) material.

[0063] This conveniently allows these ends of the corrugated reinforcing element to move relative to adjacent portions of the reinforcing element enclosed within the second layer. This is shown with reference numerals 12a and 12b and associated arrows. It will be appreciated that bending or flexing the structure about the direction of arrow C will cause portions 12a and 12b to move together. Conversely, bending the panel in the opposite direction serves to move portions 12a and 12b apart. Due to this permitted movement of adjacent portions of the reinforcing element, the structure can accommodate bending forces, thereby flexing and bending without cracking or breaking.

[0064] It will also be appreciated that the structure retains structural strength due to the connection or bonding at point 11. The exact strength and stiffness of the structure will depend on the materials used, the thickness of the first layer and the reinforcing element and the relative elastic moduli thereof compared to the elastic modulus of the second layer, i.e.

[0065] The elastic modulus of the first layer and the reinforcement layer combined = E F E R

[0066] Elastic modulus of the second layer alone = E S

[0067] E F E R >E S

[0068] This relationship ensures that the structure is allowed to flex easily while maintaining a continuous and uninterrupted surface of the first layer.

[0069] Reference below Fig. 7A and Figure 7B Another alternative embodiment is described.

[0070] Figure 3 and Figure 4 An application of the structure described herein is shown, namely a spoiler with a matching surface, which advantageously does not require a hinge arrangement.

[0071] refer to Figure 3 , a deformable or deflectable structure 7 is located between the wing box 5 and the spoiler S. In normal flight, the trailing edge of the spoiler S overlaps the leading edge of the flap 4 to provide a continuous surface.

[0072] An actuator 13 is shown coupled to the spoiler S. Movement of the actuator 13 in the direction of arrow D will cause the spoiler to move in a downward direction.

[0073] Normally in the absence of structure 7, a hinge might be required to connect the spoiler to the wing box 5, ie to provide a pivot about which the spoiler can rotate. However, the present invention conveniently not only provides a hinge function, but also provides a smooth and continuous surface 14.

[0074] refer to Figure 4 , the flaps have been deployed and the actuator 13 is activated to cause the spoiler to follow the rotation of the flaps in the downward direction. As shown in the figure, due to the way in which the points at which the reinforcing elements of the deflectable structure can be moved relative to each other, the structure 7 can be conveniently bent or deformed into Figure 4 The curve 15 is shown. This allows the first upper surface 8 to bend and provide a smooth arc between the wing box and the spoiler.

[0075] This has the advantage of increasing the effectiveness of the flaps and improving aerodynamic performance. Those skilled in the art will appreciate that any increase in aerodynamic performance can result in smaller components and structures and therefore reduced weight.

[0076] It will be appreciated that operating the actuator in the opposite direction will result in an opposite arc of the deformable structure 7 and movement of the spoiler in an upward direction (for example in applications where the spoiler is used to increase drag).

[0077] refer to Figure 5 This is further demonstrated by Figure 5 The forces and nodes of one embodiment of a deformable structure described herein are shown.

[0078] Advantageously, the arrangements described herein redistribute loads so that the structure can deform or morph into different shapes without creating unacceptably high stresses in the material, while allowing the structure to transmit applied structural and aerodynamic loads.

[0079] refer to Figure 5 , elements 1 to 6 form the main skin surface (first layer). Thus, from point a to point h a continuous skin with certain properties (length, width, thickness and stiffness) is provided.

[0080] The elements 12 to 23 form a corrugated internal reinforcement layer or element within the structure, which also has properties (length, width, thickness and stiffness).

[0081] Elements 7 to 11 represent a support or second layer, which is much less rigid than the main skin and reinforcement layers. Here, the material chosen can conveniently be, for example, rubber with a certain thickness t, so that buckling failure of the element is not possible.

[0082] An alternative arrangement in which a spring is substituted for the elastic body is described below with reference to FIG. 7 .

[0083] As discussed above, the important relationship is that the total axial stiffness between adjacent vertices in the elastomeric layer is much less than the axial stiffness of the first and reinforcing elements combined.

[0084] like Figure 5 As shown, the structure has been Figure 4 The upper loading view shows a cross section through the structure described herein, and the lower loading view shows the normal skin. The dotted lines indicate the locations of deformation.

[0085] The inventors established the following observations while developing the deformable or shape-shifting structure:

[0086] 1) The first requirement is that the deformation of the skin when loaded under aerodynamic pressure will remain at an acceptable level. Figure 5 In , force P1 represents the aerodynamic load.

[0087] When both the structure described herein and the normal conventional skin elements are optimized to meet this requirement and their deformation due to load P1 , the thickness of the structure described herein can be much thinner than the thickness of the normal conventional skin.

[0088] 2) The second requirement is that the stresses in the skin remain at acceptable levels when the structure is loaded with forces. In Figure 1, the actuation forces are represented by moments M1 and M2.

[0089] When the structure described herein and a normal conventional skin element are both pushed into an equivalent deformed shape, the stresses in the normal skin will be much greater (and unacceptable in most practical applications) than the stresses in the innovative structure described herein due to the difference in skin thickness.

[0090] As a result of evaluations 1 and 2, it has been determined that the invention described herein has a great potential to contribute to the development of shape-fitting (wing) structures.

[0091] Figure 6 A cross section of a prototype deformable aerospace structure is shown, with the elastomeric layer clearly visible at the bottom of the image. In addition, other reinforcing elements are shown positioned with each V-shaped reinforcement. The lower ends of these additional reinforcement elements are enclosed within the second layer, and at the opposite end (in the vertex closest to the first layer) another bead of elastomeric material is provided to receive the opposite end of the additional reinforcement. This structure provides further strength, which allows the structure to retain its deformable properties.

[0092] refer to Fig. 7A and Figure 7B, describes an alternative arrangement. Fig. 7A As shown, the above structure is shown using an encapsulating elastomer layer. Another way to provide the same or similar elastic properties is to use springs 16 to define a second "layer". It will be appreciated that the elastomer option allows function in two directions, while the spring embodiment allows function in a single direction.

[0093] In arrangements using an elastomer or rubber layer, the layer may contain spaces or openings on its surface or in its depth, or allow compression of the layer. This may then advantageously allow for greater curvature of the structure, i.e. tighter curved structures or curves.

[0094] It will be appreciated that the invention described herein may be applied to a variety of fluid control or directing components, where typically the use of hinges and smooth surfaces may be advantageous.

Claims

1. A deformable aerospace structure, comprising a first layer (8) and a second layer (9) spaced apart from the first layer, and defining a space between the first layer and the second layer, the space comprising one or more reinforcing elements (10) extending between the first layer and the second layer, in, The end or part of the reinforcing element close to the first layer is connected to the first layer, and the end or part (12a) of the reinforcing element close to the second layer is movable relative to the end or part (12b) of an adjacent reinforcing element close to the second layer, wherein the second layer is in the form of one or more elastic elements connecting adjacent reinforcing elements together, and wherein the elastic elements are springs.

2. The deformable aerospace structure according to claim 1, wherein: The reinforcing element is in the form of a plurality of adjacent members each alternating in direction and extending from the first layer to the second layer.

3. The deformable aerospace structure according to claim 2, wherein: The reinforcing element is in the form of a continuous member configured to alternate between the first layer and the second layer along a length of the continuous member.

4. A deformable aerospace structure according to any preceding claim, wherein: Ends or portions of adjacent reinforcing elements close to the first layer are connected to the first layer at the same position.

5. A deformable aerospace structure according to any preceding claim, wherein: The stiffness of the first layer between adjacent points at which the reinforcing element is connected to the first layer is greater than the stiffness of the second layer between adjacent points at which the reinforcing element is connected to the second layer.

6. A deformable aerospace structure according to any preceding claim, wherein: The first layer comprises an outer surface facing the air flow and an inner surface facing the reinforcement element.

7. A deformable aerospace structure according to any preceding claim, wherein: The first layer and the reinforcing element are formed from a carbon fiber reinforced plastic or aluminum material, and the second layer is formed from a rubber or silicone elastomer layer.

8. A deformable aerospace structure according to any preceding claim, wherein: The reinforcing element is in the form of a corrugated reinforcing element alternating between the first layer and the second layer along the length of the corrugated reinforcing element and defining a plurality of generally V-shaped sections.

9. An aircraft wing comprising a deformable aerospace structure according to any one of claims 1 to 8.

10. A wind turbine blade comprising a deformable aerospace structure according to any one of claims 1 to 8.

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