Non-crimp fibre forming

Abstract

The method comprises coupling non-crimp fibre (NCF) material 13 to a forming tool 15 with an elastic material 12 so that the NCF material and elastic are under tension. An elastic membrane 18 is place

Description

Background The present invention is concerned with the manufacture of the structural component in aircraft wings known in the art as spars. Although the manufacturing method is particularly suited to aircraft spar manufacture, it may be employed in other related applications or components with a similar shape. For example, the technology may be used in a variety of applications using non-crimp fabrics (NCF) to form complex 3 dimensional shapes. A technique may also be used with other material formats such as plain or harness weave fabrics. Non-crimp materials are formed of a plurality of layers, each layer having a series of strands of carbon fibres. The multiplicity of the orientation of the fibres provides the eventual cured product or component with great strength. The layers are connected together by stitching which holds the fibres in place until a resin can be applied and cured, typically in an out of autoclave environment. Specific to the aerospace sector, spars can be used in wings, horizontal or vertical tail-planes (empennage), in tail-booms of helicopters, and smaller structures in components such as winglets and flaps where rigidity is required. An aircraft wing comprises an outer aerodynamic surface over which air is caused to flow by forward motion of the aircraft. Wings generally comprise one or more spars extending within the wing from the root, where the spar connects to the fuselage, to the wing tip. The shape and contour of the spar and associated ribs (which run in a fore-aft direction of flight of the aircraft) corresponds to the desired shape of the aerofoil. The outer aerodynamic surface can then be connected to the ribs and spar (by various means) to form the wing. One conventional way of manufacturing spars is to machine the spar from a billet of aluminium or other lightweight material using CNC tools so that the precise geometry of the spars can be obtained. Conventional wings made using these techniques allow a lightweight wing to be manufactured accurately for each aircraft design providing the desired strength and stiffness. The present inventor has however devised an alternative process for optimising wing design and in particular wing spar manufacture which allows non-crimp forming techniques to be successfully and economically deployed. Summary of the Invention Aspects of the invention are set out in the accompanying claims. Viewed from a first aspect there is provided a method of forming a component from a noncrimp fibre (NCF) material, the method comprising the steps of: (A) coupling a first peripheral portion of a layer of NCF material to a forming tool, wherein an intermediate elastic material extends from a second peripheral portion of the NCF material to the forming tool, and wherein the layer of NCF material and the intermediate elastic material are in tension prior to a conforming step; (B) providing an elastic membrane over the layer of NCF material, such that the layer of NCF material is located between the forming tool and the elastic membrane; and (C) conforming the layer of NCF material to the forming tool by means of reducing a pressure between the forming tool and the elastic membrane, to bring the layer of NCF material into contact with a surface of the forming tool, and wherein the layer of NCF material and intermediate elastic material are maintained in tension during the conforming. The manufacturing method described herein allows an NCF material to be formed in a way that allows high-accuracy multi-layer components such as aircraft spars to be formed. Maintaining the NCF material and intermediate elastic material in tension throughout the forming process prevents the formation of undesirable folds or corrugations in the NCF material, thus improving the accuracy of the shape of the resultant formed component. Conforming the NCF material to the forming tool by means of reducing a pressure between the forming tool and a covering elastic membrane, allows more complex, undulating geometries to be realised in the final component, providing the designer with greater flexibility to optimise strength to weight ratios. Reducing the pressure between the forming tool and the elastic membrane may occur by means of applying a vacuum, enabling the NCF material to better conform to the shape of the surface of the forming tool. Advantageously, the vacuum may be applied to one or more conduits in the forming tool, or joints between components of the forming tool, ensuring that the vacuum is applied between the forming tool and the NCF material, and thus enabling uniform conformity of the NCF material across its length. Conforming the layer of NCF material to the forming tool may further comprise positioning a biasing element over the elastic membrane to bias the NCF material to conform to a geometry of the forming tool after and / or during reducing the pressure. This is particularly advantageous when using the claimed method to form components with an angular geometry (such as, for example, a z-shaped spar for an aircraft wing) for which the application of a vacuum alone may not be sufficient for ensuring the NCF material biases against the corner of a right angle, or acute angle on the surface of the forming tool. The biasing element, which may be in the form of a flexible silicone compactor or a noodle, may be provided on the upper surface of the elastic membrane to bias the NCF material into a corner of the surface of the forming tool. The method may further comprise an additional step of applying a pressure to an opposing side of the layer of NCF material to bias the layer of NCF material against the forming tool. This pressure may be applied by a pressurised chamber. Applying pressure to the upper surface of the NCF material in this manner enables a predetermined load to be applied to the formed NCF material, to compact and hold the NCF material in place prior to and during binder activation of the NCF material. A pressure is applied to the pressurised chamber optionally comprising a bladder such that a force is applied to the outer surface of the forming tool, wherein the pressurised chamber and optional bladder are configured to apply a force comprising both vertical and horizontal components to the outer surface of the forming tool. Applying a force comprising both vertical and horizontal components to the outer surface of the forming tool is particularly advantageous, because it is ensures that the NCF material is compacted by the pressurized chamber across its entire length, even when the forming tool has an undulating geometry. For example, if the surface of the forming tool has a vertical segment, applying a force with a horizontal component allows the NCF material that is biased against the vertical segment to be compacted. Applying a pressure across the entire length of the NCF material ensures that all parts of the material are effectively heated during binder activation. The pressurised chamber may be in the form of a housing and elastic membrane, the size and shape of which may be complimentary to the shape of the formed NCF material / forming tool. The angle at which the elastic membrane is attached to / held by the housing may be optimised to ensure that in use an equal pressure is applied to the entire NCF material, which is shaped with an undulating geometry. The shaped NCF material may then be heated in order to cure it and form the resultant component. A heating element may be coupled to the elastic membrane of the pressurised chamber such that when pressure is applied to the NCF material, the heating element if proximal to the shaped NCF material. This allows direct and highly controlled heating of the NCF material, and also allows pressure and heat to be applied to the formed NCF in sequence. The temperature of the heating element, which may be in the form of a heating mat or blanket, may be predetermined, and commence the melting of the thermoplastic outer tackifier layer which secures consecutive layers forming the NCF material together. Alternatively, the shaped NCF may be heated using a gas, heated to a predetermined temperature. The same gas may be used to simultaneously inflate the pressurised chamber, applying the pressure to the NCF material, and to heat the formed NCF material. The gas used may be shop floor supplied air. The formed NCF material may advantageously be machined on the forming tool, after removal of the pressurised chamber. Machining or mechanically trimming the NCF material on the tool allows a precise and accurate geometry of the formed component to be obtained, and provides, as an output of the forming method, a fully formed and trimmed component of the desired shaped. In an example embodiment, the NCF material may be machined or mechanically trimmed using an ultrasonic knife. This knife may, for example, be mounted on a robot. By mechanically trimming the NCF material on the tool, no further treatment of the component is required at the dry preform stage. The formed component can be transferred for further processing such as, for example, resin infusion or resin transfer moulding. The layer of NCF material may be coupled to the forming tool by means of selectably releasable fastenings. These fastenings, which may be connected to the intermediate elastic material and the opposing edge of the NCF material, allow the NCF material to be securely connected to the forming tool during the forming process. They may also advantageously connect the NCF material and intermediate elastic material to a support frame prior to the forming process, such that the NCF material can be lowered onto the forming tool at a predetermined tension. For example, the selectably releasable fastening may take the form of t-shaped fastenings or pins, which may drop into holes in the forming tool to secure the NCF material in place on the forming tool. The layer of NCF material and intermediate elastic material may be maintained in tension during the forming process, such that an elongation of the intermediate elastic material does not exceed between 40-50% of an unstretched length of the intermediate elastic material. This elongation limit ensures that enough tension is applied to the NCF material throughout the forming process that the NCF is preventing from folding or wrinkling, but is still able to accurately conform to the shape of the forming tool. Furthermore, this elongation limit maximises the life of the intermediate elastic material, allowing it to be reused for formation of a plurality of components, since the elastic limit of the material is not exceeded during the forming process. The layer of NCF material and intermediate elastic material may be loaded onto the forming tool using a support having a shape complementary to the shape of the tool. As is discussed above, this enables a predetermined tension to be applied to the NCF material and intermediate elastic material prior to loading onto the forming tool. The forming tool is configured for forming a component having an undulating geometry, such as a z-shape, or a step-shape. The component may be an undulating spar for an aircraft wing. Viewed from a second aspect, there is provided an aero-structure component manufactured according to the method provided above. The component may be a spar. 5 Viewed from a third aspect, there is provided a Non-Crimp Fabric (NCF) forming apparatus for use in the method discussed above, comprising: a forming tool comprising: one or more vacuum conduits; a plurality of recesses for receiving selectably releasable fastenings; and a hinge and fastening for attaching an intermediate elastic material to the forming tool; the intermediate elastic material; and an elastic membrane; wherein: the intermediate elastic 10 material is located in use between the forming tool and a layer of NCF material; the layer of NCF material and intermediate elastic material are maintained in tension; the elastic membrane is connectable to the forming tool such that, in use, the elastic membrane is closed over the layer of NCF material; and the forming tool comprises means for reducing a pressure between the forming tool and the elastic membrane. 15 Brief Description of the Drawings One or more embodiments of the invention will now be described, by way of example only, and with reference to the following figures in which: Figure 1A shows an initial arrangement of an NCF material ply and former boards prior to a forming process. Figure 1B shows an arrangement in which the NCF material ply and former boards are secured to a frame. Figure 1C shows an initial arrangement of the ply and forming apparatus prior to a forming process in accordance with an embodiment. Figure 1D shows a step in a forming process according to an embodiment, in which the ply is loaded onto a forming tool. Figure 1E shows a step in a forming process according to an embodiment, in which an elastic membrane is closed over the ply. Figure 1F shows a step in a forming process according to an embodiment, in which the elastic membrane and ply conform to or bias against the shape of the upper surface of the forming tool. Figure 1G shows a step in a forming process according to an embodiment in which a biasing means is provided to better conform the ply to the geometry of the forming tool. Figure 1H shows an assembly for providing heat and pressure to the ply. Figure 11 shows a step in a forming process according to an embodiment in which the assembly for providing heat and pressure to the ply is lowered over the forming tool and secured in place. Figure 1J shows a step in a forming process according to an embodiment in which pressure and heat are applied to the ply. Figure 1K shows a step in a forming process according to an embodiment in which the assembly for applying heat and pressure is removed, and the ply is machined on the forming tool. Figures 2A and 2B show alternative forms of NCF materials and component parts. Figure 3 shows a spar of an aircraft wing that may be manufactured by a process described herein. While the invention is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and are herein described in detail. It should be understood however that the drawings and detailed description attached hereto are not intended to limit the invention to the particular form disclosed but rather the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the claimed invention. Any reference to prior art documents in this specification is not to be considered an admission that such prior art is widely known or forms part of the common general knowledge in the field. As used in this specification, the words “comprises”, “comprising”, and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean “including, but not limited to”. The invention is further described with reference to the following examples. It will be appreciated that the invention as claimed is not intended to be limited in any way by these examples. It will also be recognised that the invention covers not only individual embodiments but also combination of the embodiments described herein. The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only and are not exhaustive and / or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the spirit and scope of the claimed invention. Various embodiments of the invention may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc., other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future. It will be recognised that the features of the aspects of the invention(s) described herein can conveniently and interchangeably be used in any suitable combination. Detailed Description Figures 1A to 1K demonstrate each step of the process described herein. Each step will be described separately as follows: Tooling Set-up Figure 1A illustrates the initial arrangement of the NCF material 13 and the former boards 10 prior to the forming of the spar component. First, a layer or sheet of the NCF material 13, such as TENAX-E, DRNF, manufactured by Teijin, is prepared having a length and size corresponding to the eventual shape of the spar. The process is the repeated to build the spar thickness. For example, spars for commercial airliners are approximately 20mm at the thickest point, with an NCF of 0.5mm thickness. Thus, the process is repeated 40 times. In another arrangement multiple layers may be added to reduce manufacturing time. The term ‘ply’ is used herein to refer to the NCF material being shaped or formed according to the disclosed method. However, it should be recognised that the NCF material may be a single ply or a stack of plies formed, for example, according to the method discussed above. The NCF material 13, or ply 13, is now connected to the pair of opposing former boards 10. The ply 13 is connected to one of the pair of opposing former boards 10 by means of an intermediate elastic material 12. The intermediate elastic material 12 is an intermediate connection between the ply 13 and one of the pair of former boards 10 which can stretch elastically. This may be a continuous strip or a plurality of strips, each strip able to stretch as the ply 13 conforms to the shape of the forming tool 15. The intermediate elastic material 12 may comprise Airtech A4000. A length of the intermediate elastic material 12 is selected such that during the conforming process the length of the stretched intermediate elastic material 12 does not exceed 145% of the original unstretched length. The intermediate elastic material 12 may be attached to one of the pair of former boards 10 and the ply 13 using an adhesive 11. The adhesive 11 may comprise strips of double sided tape, or polyester films coated on both with pressure sensitive silicone adhesive. The former boards 10 extend along each side of the forming tool 15 and may be single elongate members or may alternatively be divided into multiple sections. The former boards 10 act to apply the movement to bring the ply 13 into contact with the forming tool 15 and to hold the material in place during the process described below. Turning to Figure 1B, the next stage is shown. Here, the former boards 10 are connected to and held by a supporting frame 14 having a shape complimentary to the shape of the forming tool 15. The supporting frame 14 may otherwise be referred to as a handling jig 14. The former boards 10 are held by the handling jig 14 such that a pre-tension is applied to the intermediate elastic material 12, and the ply 13 is held flat. Just enough tension is applied to remove the slack from the ply 13 but without applying excessive loading. This tension is maintained by the connection of the former boards 10 to the handling jig 14. Figure 1C illustrates the initial set-up of the forming apparatus before the spar component is formed. The shape of the upper surface of the forming tool 15 corresponds to the desired final shape of the spar component, as will be understood by someone skilled in the art. As illustrated in Figure 1C, the forming tool 15 may have an undulating geometry and, for example, be a step- or z-shaped tool, for forming a step- or z-shaped spar component. The shaped outer surface of the forming tool 15 is the surface against which the ply 13 is to be bias. Importantly, the resin is not introduced at this stage, however the forming tool 15 surface will have been treated with a chemical release agent (such as Frekote) during manufacture, this is typically wiped on and allowed to dry. This may be refreshed at a later point. A film is not applied directly to the forming tool 15 surface, just instead to the edges of the NCF. Release agent is applied to the tool surface prior to use, and can be applied onto the whole surface of the tool. The forming tool 15 further comprises selectably releasable fastenings 16 by which the former boards 10 connected to the ply 13 may be attached to the forming tool 15. The selectably releasable fastenings 16 may comprise a retraceable clamping mechanism. In an example embodiment, the attachment means may comprise bolts for attaching the former boards 10 to the forming tool 15. In another example embodiment, the selectably releasable fastenings 16 may comprise holes into which t-shaped fastenings or pins connected to or comprising the former boards 10 may drop into, in order to secure the ply 13 to the forming tool 15. The forming apparatus further comprises an elastic membrane 18, connected to a distal end of the forming tool 15. The elastic membrane 18 is configured to also connect to an opposing end of the forming tool 15 such the connected ends of the elastic membrane 18 are distal to the attachment means by which the former boards 10 connected to the ply 13 may be attached to the forming tool 15. Accordingly, when the elastic membrane 18 is closed over the ply 13 on the tool, the elastic membrane 18 extends over the entire surface of the ply 13. The elastic membrane 18 may be made from a silicone or fluoroelastomer material (such as Mosites), which allows the elastic membrane 18 to be reused after the forming process is complete. The forming tool 15 may also comprise one or more machining grooves 17, enabling the resultant formed ply 13 to be machined on the tool. Now the NCF material or ply 13 is ready to move into contact with the forming tool 15. Preliminary Forming Tool Contact Turning to Figure 1D, the next stage of forming is shown. Here, the handling jig 14 is lowered towards the surface of the forming tool 15, causing at least a section of the ply 13 to come into initial contact with the outer surface of the forming tool 15. The NCF assembly including the ply 13 and the intermediate elastic material 12 is then loaded onto the forming tool 15 and secured by the selectably releasable fastenings 16 and the former boards 10. The NCF assembly is secured to the forming tool 15 such that a tension of the ply 13 and the intermediate elastic material 12 is maintained. Just enough tension is applied to remove the slack from the ply 13 but without applying excessive loading. In an example embodiment, the selectably releasable fastenings 16 may comprise bolts, such that the former boards 10 are bolted to the forming tool 15. In another example embodiment, the selectably releasable fastenings 16 may comprise holes, and so to secure the NCF assembly to the forming tool 15 t-shaped fastenings or pins connected to or comprising the former boards 10 are dropped into the holes. Once the former boards 10 are secured to the forming tool 15, the handling jig 14 is removed. The movement of the handling jig 14 / former boards 10 may be through any suitable actuator arrangement which may be electrically / pneumatically / hydraulically controlled. The movement may be controlled manually or using computer control, such as with a pre-programmed sequence. Final Location of NCF Ply Turning to Figure 1E, the elastic membrane 18 is closed over the NCF assembly by connecting the elastic membrane 18 to distal ends of the forming tool 15. When the elastic membrane 18 is closed to the forming tool 15, the entirety of the NCF assembly is enclosed between the forming tool 15 and the elastic membrane 18. The closure of the elastic membrane 18 to the forming tool 15 forms a hermetic / quasi-hermetic seal between the elastic membrane 18 and the forming tool 15. Turning to Figure 1F, a pressure between the elastic membrane 18 and the forming tool 15 is reduced causing the elastic membrane 18 and ply 13 to conform to or bias against the shape of the upper surface of the forming tool 15. The pressure may be reduced by applying a vacuum. In particular a vacuum may be applied to one or more holes or conduits in the forming tool 15, or to a join between components of the forming tool 15. As the ply 13 conforms to the shape of the upper surface of the forming tool 15, the intermediate elastic material 12 stretches to enable the entire length of the ply 13 to bias against the tool. During the conforming step, the intermediate elastic material 12 may not stretch by more than 40-50% of its unstretched length. Preferably, the intermediate elastic material 12 may not stretch by more than 45% of its unstretched length. This enables the ply 13 to be maintained in tension when the vacuum is applied, and so prevents wrinkling or folding of the ply 13. In some cases, the vacuum may not be sufficient for biasing the entire length of the ply 13 to the shape of the upper surface of the forming tool 15. Therefore, turning to Figure 1G, a biasing means 19 in the form of a flexible silicone compactor or noodle may be provided on the upper surface of the elastic membrane 18 to bias the elastic membrane 18 and ply 13 into a corner of the outer surface of the forming tool 15. Application of Pressure and Heat Turning to Figure 1H, an assembly for providing heat and pressure to the ply 13 is positioned above the upper surface of the forming tool 15. In a preferred arrangement, the assembly comprises a pressurized chamber including a box structure 20 and a flexible membrane 21 which is proximal to the forming tool 15. In an example embodiment, a heating element 22, such as a heat blanket, may be provided on the internal surface of the flexible membrane 21 for providing heat to the formed ply 13. The pressurized chamber may additionally include a bladder inside the box structure 20. The size of the assembly may be selected to complement the length of the component being formed. In an embodiment in which the forming tool 15 is a step-shaped or z-shaped tool, the assembly for providing heat and pressure may be configured such that in a resting position, the flexible membrane 21 is held at a slant. This configuration enables the assembly, during use, to apply a force to the formed ply 13 having both vertical and horizontal components. Turning to Figure 11, the assembly is lowered over the loaded forming tool 15, and secured in place, for example, by mechanical fastenings or locks so as to prevent the assembly from lifting upwards when pressure is applied to the ply 13. Turning to Figure 1J, the next stage of forming is shown. Pressure and heat are applied to the forming tool 15 and shaped ply 13 in sequence, in order to activate the binder or cure the ply 13. In an embodiment, pressure is applied to the ply 13 by filling the pressurized chamber with gas, causing the flexible membrane 21 to become distended and press against the surface of the forming tool 15 against which the ply 13 is biased. In an alternative embodiment, a bladder inside the pressurized chamber is inflated to provide the same effect. Due to the slanted angle of the flexible membrane 21, the force applied by the assembly when the pressurized chamber or bladder is inflated includes both horizontal and vertical components. This allows a force to be applied to the entire surface of the ply 13, even when conforming the ply 13 to a stepshaped forming tool 15 having vertical segments. In an embodiment, the pressure inside the assembly may not exceed 1 Bar. After a pressure has been applied to the formed ply 13, the formed ply 13 is heated. In an embodiment, a heat blanket is provided on the inside surface of the flexible membrane 21, such that when the pressure is applied, the heat blanket within close proximity of the length of the formed ply 13. In this embodiment, the heat is applied to the ply 13 by heating the heating element 22 once the pressure has been applied. In an alternative embodiment, the ply 13 is heated by filling the pressurized chamber or bladder with a hot gas, for example, shop floor supplied pressurised dry air. The ply may be heated to a temperature between 60 and 180 degrees Celsius, with the exact temperature selected based on the binder material type on the ply. The skilled person would recognise that further methods of heating the formed ply 13 are also applicable. Removing the Pressure and Heat, and Trimming Turning to Figure 1K, the assembly for applying heat and pressure is removed, and the elastic membrane 18 attached to the forming tool 15 is detached at one end to allow access to the formed ply 13 or stack of plies. The ply 13 or stack of plies may then be machined or trimmed on the tool, to form the final formed piece. The trimming may be manufacturing edge of part (MEOP) trimming. The trimming may be performed in a single motion, for example, where the formed piece is comprised of a single ply. Alternatively, the trimming may be performed in multiple motions, for example, where the formed piece is comprised of a stack of plies with a thickness that is greater than the length of the blade. The ply 13 or stack of plies may alternatively be machined or trimmed off the tool. According to an invention described herein it is possible to form extremely long NCF components, including complete aircraft wing spars which can extend up to and beyond 17 metres in length. Increased lengths may be achieved with a modular manufacturing arrangement with a series of manufacturing apparatuses lined in series. The may allow for very long structural components to be formed. Figure 2A shows the make-up of an NCF material itself that may be used in the arrangements described herein. The NCF material in figure 2A comprises carbon fibre layers interposed 5 between tougher or veil layers and coated with a binder layer as shown. The binder may be a powder binder. The arrangement is then reinforced or held together with stitching to create the flexible fabric properties of the material. Figure 2B shows an alternative layered structure of an NCF material having a different arrangement and composition of layers. 10 Figure 3 illustrates an example view of a spar of the type used in an aircraft wing, which may advantageously be manufactured according to the process described herein. As can be seen from Figure 3, the spar comprises a complex z- or step-shaped geometry. The process described herein allows this complex geometry to be made for spars having long lengths.

Claims

1. A method of forming a component from a non-crimp fibre (NCF) material, the method comprising the steps of:(A) coupling a first peripheral portion of a layer of NCF material to a forming tool, wherein an intermediate elastic material extends from a second peripheral portion of the NCF material to the forming tool, and wherein the layer of NCF material and the intermediate elastic material are in tension prior to a conforming step;(B) providing an elastic membrane over the layer of NCF material, such that the layer of NCF material is located between the forming tool and the elastic membrane; and(C) conforming the layer of NCF material to the forming tool by means of reducing a pressure between the forming tool and the elastic membrane, to bring the layer of NCF material into contact with a surface of the forming tool, and wherein the layer of NCF material and intermediate elastic material are maintained in tension during the conforming.

2. The method as claimed in claim 1, wherein reducing the pressure between the forming tool and the elastic membrane occurs by means of applying a vacuum.

3. The method as claimed in claim 2, wherein the vacuum is applied by applying a vacuum to one or more conduits in the forming tool, or to joints between components of the forming tool.

4. The method as claimed in any of claims 1 to 3, wherein conforming the layer of NCF material to the forming tool further comprises positioning a biasing element over the elastic membrane to bias the NCF material to conform to a geometry of the forming tool after and / or during reducing the pressure.

5. The method as claimed in any preceding claim, further comprising an additional step of applying a pressure to an opposing side of the layer of NCF material to bias the layer of NCF material against the forming tool.

6. The method as claimed in claim 5, wherein the pressure is applied by a pressurised chamber optionally comprising a bladder.

7. The method as claimed in claim 6, wherein a pressure is applied to the pressurised chamber optionally comprising a bladder such that a force is applied to the outer surface of the forming tool, wherein the pressurised chamber and optional bladder are configured to apply a force comprising both vertical and horizontal components to the outer surface of the forming tool.

8. The method as claimed in claim 6 or claim 7, wherein the pressurised chamber is in the form of a housing and an elastic membrane.

9. The method of claim 8, wherein a heating element is coupled to the elastic membrane of the pressurised chamber.

10. The method as claimed in claim 9, wherein upon applying the pressure, the heating element is proximal to the shaped NCF.

11. The method as claimed in claim 10, further comprising heating the shaped NCF using the heating element after applying the pressure.

12. The method as claimed in claim 8, further comprising heating the shaped NCF using a gas.

13. The method as claimed in any preceding claim, further comprising an additional step of machining the shaped NCF to produce a predetermined component geometry.

14. The method as claimed in claim 13, wherein the formed NCF is machined on the forming tool.

15. The method as claimed in any preceding claim, wherein the layer of NCF material is coupled to the forming tool by means of selectably releasable fastenings.

16. The method as claimed in any preceding claim, wherein the layer of NCF material and intermediate elastic material are maintained in tension during the forming process, such that an elongation of the intermediate elastic material does not exceed between 40-50% of an unstretched length of the intermediate elastic material.

17. The method as claimed in any preceding claim, wherein the layer of NCF material and intermediate elastic material are loaded onto the forming tool using a support having a shape complementary to the shape of the tool.

18. The method as claimed in any preceding claim, wherein the forming tool is configured for forming a component having an undulating geometry.

19. The method as claimed in any preceding claim, wherein the component is an undulating spar for an aircraft wing.

20. An aero-structure component manufactured according to the method of any of claims 1 to 19.

21. An aero-structure component according to claim 20, wherein the component is a spar.

22. An aircraft comprising an aero-structure component according to claim 20 or claim 21.

23. A Non-Crimp Fabric (NCF) forming apparatus for use in the method of any of claims 1 to 19, comprising:a forming tool comprising:one or more vacuum conduits;a plurality of recesses for receiving selectably releasable fastenings; anda hinge and fastening for attaching an intermediate elastic material to the forming tool;the intermediate elastic material; andan elastic membrane;wherein:the intermediate elastic material is located in use between the forming tool and a layer of NCF material;the layer of NCF material and intermediate elastic material are maintained in tension;the elastic membrane is connectable to the forming tool such that, in use, the elastic membrane is closed over the layer of NCF material; andthe forming tool comprises means for reducing a pressurebetween the forming tool and the elastic membrane.T +44(0)30 0300 2000A

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