COMPOSITE CONNECTORS AND METHODS OF MANUFACTURING THE SAME

Abstract

A method of manufacturing a composite (e.g. fibre-reinforced polymer) connector for a fluid transfer conduit includes: providing a tubular mandrel which extends substantially parallel to a central axis C; providing a former on the tubular mandrel which extends substantially perpendicular to the central axis C; and winding continuous fibre reinforcement, impregnated with a thermosetting polymer, around the mandrel to form a tubular hub portion which extends substantially parallel to the central axis C and over the former to form a flange portion 308 which extends from the hub portion at an angle to the central axis C. Winding the continuous fibre reinforcement over the former includes passing the continuous fibre reinforcement across a first surface of the former that is substantially perpendicular to the central axis C and across a second surface of the former such that the former is encapsulated as a core for the flange portion.

Claims

1. A method of manufacturing a composite connector for a fluid transfer conduit, the method comprising: providing a tubular mandrel which extends substantially parallel to a central axis; providing a former on the tubular mandrel which extends substantially perpendicular to the central axis; and winding continuous fibre reinforcement, impregnated with a thermosetting polymer, around the mandrel to form a tubular hub portion which extends substantially parallel to the central axis and over the former to form a flange portion which extends from the hub portion at an angle to the central axis; wherein winding the continuous fibre reinforcement over the former comprises passing the continuous fibre reinforcement across a first surface of the former that is substantially perpendicular to the central axis and across a second surface of the former such that the former is encapsulated as a core for the flange portion.

2. The method of claim 1, wherein passing the continuous fibre reinforcement across the first surface of the former comprises passing across the first surface in a radial direction to pass over an edge of the first surface before passing across the second surface.

3. The method of claim 1, wherein passing the continuous fibre reinforcement across the first surface of the former comprises passing across the first surface in a circumferential direction.

4. The method of claim 1, wherein passing the continuous fibre reinforcement across the first surface of the former comprises passing across the first surface in multiple orientations.

5. The method of claim 1, further comprising: applying a consolidation force to the flange portion in a direction substantially parallel to the central axis.

6. The method of claim 1, further comprising: removing the tubular mandrel and leaving the former encapsulated as a core for the flange portion.

7. The method of claim 1, further comprising: removing the tubular mandrel and the former.

8. The method of claim 7, wherein removing the tubular mandrel and the former comprises destroying at least part of the tubular mandrel and/or the former.

9. The method of claim 1, wherein the former is non-structural.

10. The method of claim 1, wherein the tubular mandrel and/or the former is made of a sacrificial material.

11. The method of claim 1, wherein the continuous fibre reinforcement in the flange portion extends to an outer circumferential edge of the flange portion.

12. The method of claim 1, further comprising: winding the continuous fibre back onto the mandrel on either side of the former.

13. The method of claim 1, further comprising: curing the hub portion and the flange portion.

14. The method of claim 1, further comprising: forming at least one fixing point for the flange portion by arranging the continuous fibre reinforcement in a pattern around the fixing point.

15. The method of claim 1, wherein winding the continuous fibre comprises a filament winding process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Certain examples of the present disclosure will now be described with reference to the accompanying drawings in which:

[0057] FIG. 1 is a cross sectional view of the connection between a connector and a fluid transfer conduit;

[0058] FIGS. 2A and 2B show schematic perspective views of composite connectors for a fluid transfer conduit according to examples of the present disclosure;

[0059] FIG. 3 illustrates an example of a single connector winding process;

[0060] FIG. 4 illustrates an example of a double connector winding process; and

[0061] FIGS. 5A to 5C schematically illustrate the different orientations of continuous fibre reinforcement resulting from such winding processes.

DETAILED DESCRIPTION

[0062] FIG. 1 shows the interface between a connector 2 and a cylindrical fluid transfer conduit 4 that extends parallel to a central axis C. The connector 2 comprises a cylindrical hub portion 6, which also extends parallel to the central axis C, and a flange portion 8, which extends from an end of the hub portion 6 in a direction perpendicular to the central axis C. The flange portion 8 further comprises a through-hole 10, by which the connector 2 may be secured to another structure, e.g. an aircraft wing.

[0063] The hub portion 6 encloses a connection portion 12 of the fluid transfer conduit 4. An elastomeric O-ring 14 is located between the hub portion 6 and the connection portion 12, retained between an inner wall of the hub portion 6 and an outer wall of the fluid transfer conduit 4. The O-ring 14 is confined by two retaining ridges 16 which extend radially outwards from the connection portion 10 of the fluid transfer conduit 4.

[0064] The O-ring 14 provides a seal between the connector 2 and the conduit 4, such that fluid may flow along the conduit 4 and into the connector 2 without escaping. In addition, the configuration of O-ring 14 between the connection portion 12 and the hub portion 6 allows the fluid transfer conduit 4 to move a small distance in the direction of the central axis C relative to the connector 2 without compromising the seal. This enables a structure to which the connector 2 is secured to move or flex a small amount without imparting large stresses on the conduit 4 (as would be the case if the connector 2 was rigidly attached to the conduit 4). Instead, the conduit 4 “floats” on the O-ring 14 such that it can slide longitudinally a small distance without breaking the seal. For example, the structure to which the connector 2 is attached may be an aircraft wing spar, which is designed to move a small amount during flight as the wing flexes due to aerodynamic load and/or temperature fluctuations. The fluid transfer conduit 4 may comprise a fuel pipe located within the wing which must therefore be able to cope with the wing flex during flight.

[0065] FIGS. 2A and 2B are schematic perspective views of composite connectors 102, 202 according to examples of the present disclosure. The connectors 102, 202 each comprise a cylindrical hub portion 106, 206 which extends parallel to a central axis C, and a flange portion 108, 208 which extends perpendicular to the central axis C from an end of the hub portion 106, 206. Through-holes 114, 214 are formed in the flange portions 108, 208. The flange portions 108, 208 have different shapes in FIGS. 2A and 2B.

[0066] Each hub portion 106, 206 comprises a thermosetting polymer resin matrix reinforced with continuous hoop-wound (i.e. circumferentially-orientated) fibre reinforcement 110, 210. The hoop-wound fibre reinforcement 110, 210 provides each hub portion 106, 206 with high hoop strength such that the hub portions 106, 206 can resist large internal pressures. It also makes the hub portions 106, 206 very stiff, such that large internal pressures cause negligible radial expansion.

[0067] As shown in FIG. 2A, the flange portion 108 comprises the same thermosetting polymer resin matrix with the continuous fibre reinforcement 110 extending from the hub portion 106 into the flange portion 108. The continuous fibre reinforcement 110 in the flange portion 108 is wound at varying angles, resulting in a mixture of radial and circumferential fibre directions, to give the required structural strength.

[0068] Although not shown in FIG. 2B, the continuous fibre reinforcement 210 also extends from the hub portion 206 into the flange portion 208 of the composite connector 202, the continuous fibre reinforcement 210 being hoop-wound (i.e. circumferentially-orientated) in the hub portion 206 and oriented at various radial and/or circumferential angles in the flange portion 208.

[0069] A single winding process for manufacturing a composite connector according to one example of the present disclosure will now be described with reference to FIG. 3.

[0070] An annular lightweight former 302 is fitted around a cylindrical mandrel 304 which extends substantially parallel to a central axis C. Using conventional filament winding techniques, continuous fibre reinforcement is wound onto the mandrel 304 and around the former 302 to form a tubular hub portion 306 and a flange portion 308 in which the former 302 is encapsulated. The former 302 thus acts as a core of the flange portion 308.

[0071] The continuous fibre reinforcement 306 may be pre-impregnated with a thermosetting polymer resin (“pre-preg”), or may be passed through a bath of thermosetting polymer resin (not shown) just prior to being wound onto the mandrel 304 (“wet wound”), or may be wound dry and subsequently vacuum infused with a thermosetting polymer resin after winding.

[0072] Once a sufficient quantity of continuous fibre reinforcement has been applied to the mandrel 304 and former 302 (e.g. when the former 302 is fully encapsulated), the hub and flange portions 306, 308 are then cured to form an integrated composite connector 309. During and/or after the curing process, an axial compressive consolidation force 310 may be applied to the flange portion 308, to consolidate the composite material in the flange portion 308 and eliminate any voids that may have formed during the winding process.

[0073] Once the curing process is complete, the connector 309 is extracted from the mandrel 304. Although not shown in FIG. 3, the connector 309 may then undergo one or more machining steps, for example to remove excess material and/or to form additional features as required.

[0074] An alternative, double wind process for manufacturing a composite connector according to one example of the present disclosure will now be described with reference to FIG. 4.

[0075] An annular sacrificial former 402 is fitted around a cylindrical mandrel 404 which extends substantially parallel to a central axis C. Using conventional filament winding techniques, continuous fibre reinforcement is wound onto the mandrel 404 on both sides of the former 404 and around and over the former 402 to form a tubular structure 405 comprising two tubular hub portions 406 extending from either side of a central flange-forming portion 408, in which the former 402 is encapsulated.

[0076] Once a sufficient quantity of continuous fibre reinforcement has been applied to the mandrel 404 and former 402 (e.g. when the former 402 is fully encapsulated), the hub and flange-forming portions 406, 408 are then cured. During and/or after the curing process an axial compressive consolidation force 410 may be applied to the flange-forming portion 408, to consolidate the composite material in the flange-forming portion 408 and eliminate any voids that may have formed during the winding process.

[0077] The cured tubular structure 405 is then extracted from the mandrel 404, and split along a central plane P, which runs through the flange-forming portion 408 perpendicularly to the central axis C. This divides the cured tubular structure 405 into two composite connectors, each comprising one hub portion 406 and a flange portion made up of one half of the flange-forming portion 408. The sacrificial former 402, which is no longer enclosed by the continuous fibre reinforcement, can be removed.

[0078] Each connector may then undergo one or more machining steps, for example to remove excess material and/or to form additional features as required.

[0079] FIGS. 5A-C provide an overview example of how continuous fibre reinforcement (e.g. in the form of wet impregnated or pre-preg fibre tow) is used to create a connector comprising a hub portion and a flange portion.

[0080] As shown in FIG. 5A, to help reduce the risk of ‘bridging’ between the hoop (circumferentially-oriented) layers of continuous fibre reinforcement in the hub portion and the continuous fibre reinforcement extending at an angle of up to 90° to the central axis in the flange portion, additional hoop (circumferentially-oriented) layers of continuous fibre reinforcement may be applied in a transition portion 500 to provide a ramped surface to turn the low angle fibre around from the mandrel 504 to the former 505.

[0081] FIG. 5B shows an example of a connector 502 comprising a flange portion 508 and a hub portion 506. Predominantly hoop wound (circumferentially-oriented) continuous fibre reinforcement 510 can be seen in the hub portion 506, which increases the ability of the hub portion 506 to withstand radial forces. Although not shown in FIG. 5B, helical layers of continuous fibre reinforcement may also be present in the hub portion 506, e.g. to increase resistance to axial forces in service.

[0082] FIG. 5C provides an overview example of how continuous fibre reinforcement 512 may be placed in the flange portion 508 to achieve required part strength requirements. Winding equipment could be programmed to produce any number of arrangements to achieve the desired strength properties. The wind angles over the surface of the former may vary to account for torsional and axial loads in operation. Known multi-axis winding control allows for continuous fibre reinforcement to be wound at a variety of angles and positions to achieve this.