Composite connectors and methods of manufacturing the same

Abstract

A method of manufacturing a composite (e.g. fibre-reinforced polymer) connector comprises: manufacturing a tubular hub portion which extends substantially parallel to a central axis C, the hub portion comprising a thermoplastic polymer reinforced with continuous, circumferentially-oriented fibre reinforcement; placing the hub portion into a mould featuring at least one cavity; and introducing polymer into the mould so as to fill the at least one cavity to form a flange portion around the hub portion.

Claims

1. A connection system comprising: a composite connector comprising: a hub portion comprising a tube with an inner wall which extends parallel to a central axis in an overmoulding section of the tube; and a flange portion which extends from the overmoulding section of the tube at an angle to the central axis; wherein the hub portion comprises a thermoplastic polymer matrix reinforced with fibre reinforcement, said fibre reinforcement including continuous circumferentially-oriented fibre reinforcement containing at least some individual constituent filaments which extend entirely around a circumference of the hub portion; wherein the flange portion comprises a polymer that is moulded onto the overmoulding section of the tube, and wherein no fibre reinforcement in the hub portion extends from the tube into the flange portion; and a fibre-reinforced polymer fluid transfer conduit connected to the hub portion, wherein the composition and orientation of the fibre reinforcement within the hub portion is selected such that the coefficient of thermal expansion and/or the stiffness of the hub portion matches that of the fluid transfer conduit; wherein the fibre-reinforced polymer fluid transfer conduit comprises continuous circumferentially-oriented fibre with a fibre angle that differs from a fibre angle of the continuous circumferentially-oriented fibre reinforcement in the hub portion by no more than 15.

2. The system of claim 1 wherein the flange portion comprises a thermoplastic polymer.

3. The system of claim 1 further comprising one or more strengthening or stiffening structures extending between the flange portion and the hub portion.

4. The system of claim 1 wherein the flange portion comprises chopped-fibre reinforcement.

5. The system of claim 1 wherein the flange portion comprises at least one through-hole.

6. The system of claim 1 wherein the flange portion is perpendicular to the central axis of the hub portion.

7. The system of claim 1 wherein the continuous circumferentially-oriented fibre reinforcement extends at an angle of more than 80 to the central axis.

8. The system of claim 1 the composite connector further comprising at least one non-fibre material additive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Certain examples of the present disclosure will now be described with reference to the accompanying drawings in which:

(2) FIG. 1 is a cross sectional view of the connection between a connector and a fluid transfer conduit;

(3) FIG. 2 shows a schematic perspective view of a composite connector for a fluid transfer conduit according to an example of the present disclosure;

(4) FIG. 3 shows the composite connector with a fluid transfer conduit installed therein;

(5) FIG. 4 shows a schematic perspective view of a composite connector according to another example of the present disclosure; and

(6) FIG. 5 is a flow diagram detailing various steps in a method of manufacturing a composite connector according to an example of the present disclosure.

DETAILED DESCRIPTION

(7) 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 rib.

(8) 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.

(9) 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 rib, 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.

(10) FIG. 2 is a schematic perspective view of a composite connector 102 according to an example of the present disclosure. The connector 102 comprises a cylindrical hub portion 106 which extends parallel to a central axis C and a disc-like flange portion 108 which extends perpendicularly from an end of the hub portion 106.

(11) The hub portion 106 comprises a thermoplastic polymer matrix reinforced with continuous hoop-wound (circumferential) fibre 110. The hoop-wound fibre 110 provides the hub portion 106 with high hoop strength such that the hub portion can resist large internal pressures. It also makes the hub portion 106 very stiff, such that large internal pressures cause negligible hoop expansion. The flange portion 108 is preferably moulded onto the hub portion 106 using conventional injection moulding processes. Both the hub portion 106 and the flange portion 108 may be made from a thermoplastic polymer.

(12) The composite connector 102 further comprises several strengthening ribs 105, which extend between the disc of the flange portion 108 and the hub portion 106. These strengthen the connection between the flange portion 108 and the hub portion 106 and provide the connector 102 with an increase resistance to bending loads. The strengthening ribs 105 may also comprise a thermoplastic polymer, optionally with chopped-fibre reinforcement.

(13) FIG. 3 shows a schematic perspective view of the composite connector 102 in use, connecting one end of a composite fuel pipe 104 to a wing rib 118 of an aircraft. The composite fuel pipe 104 extends into the hub portion 106 and floats inside on an O-ring (not shown), which also serves to seal the connection. The connector 102 is secured rigidly to the rib 118 via four bolts 120 (only three are visible in this Figure).

(14) During flight, due to aerodynamic forces and/or temperature based expansion/contraction, the wing rib 118 (and thus the connector 102) moves relative to fuel pipe 104. However, because the composite fuel pipe 104 floats on an O-ring, it is able to move relative to the connector 102 without compromising the connection.

(15) The composite fuel pipe 104 is constructed from fibre-reinforced polymer, and comprises a high proportion of hoop wound fibre reinforcement 122. This provides the fuel pipe 104 with high hoop strength. In addition, the high proportion of hoop-wound fibre-reinforcement 122 in the fuel pipe 104 means that its coefficient of thermal expansion (hoop CTE) is dominated by that of the fibre-reinforcement 122, rather than the polymer matrix.

(16) As mentioned above, the hub portion 106 also comprises a high proportion of hoop fibre reinforcement 110. As such, the CTE of the hub portion 106 is also dominated by that of the continuous circumferentially-oriented fibre reinforcement 110. As a result, the CTEs of the pipe 104 and the hub portion 106 are substantially equal and any hoop thermal expansion or contraction of the pipe 104 is matched by the hub portion 106. This ensures that the connection between the connector 102 and the pipe 104 remains intact (i.e. the pressure on the O-ring remains constant) over a wide temperature range (typically 55 C. to 90 C.).

(17) The axial CTE of the hub portion 106 and composite pipe 104 may not be matched but, as highlighted above, a small amount of axial differential movement (e.g. caused by greater axial thermal expansion of the pipe 104 than the hub portion 106) may be tolerated without any impact on the integrity of the O-ring seal.

(18) FIG. 4 shows an example of a double-ended composite connector 102.

(19) A method of manufacturing a composite connector for a fluid transfer conduit according to an example of the present disclosure will now be described with reference to FIG. 5. Firstly, in step 502, a tubular hub portion 106 is manufactured using thermoplastic polymer reinforced with continuous, circumferentially-oriented fibre reinforcement (optionally along with continuous fibres oriented in other directions, for example axially or helically, where necessary to meet loading conditions). In this example an automated fibre placement (AFP) technique is used to manufacture the hub portion 106 although alternative manufacturing techniques known in the art may also be used (e.g. a conmingled yarn winding or braiding process in which a commingled yarn comprising fibre reinforcement intermingled with thermoplastic polymer fibre may be wound onto a mandrel using conventional filament winding processes). Narrow slit tape of pre-impregnated thermoplastic tows may also be braided, in multiple layers, to create the hub portion 106.

(20) The hub portion 106 is then placed into an injection moulding tool in step 504. The injection moulding tool comprises a mould with a cavity which is shaped to produce a flange portion 104 around the hub portion 106 with the desired shape and dimensions.

(21) Subsequently, in step 506, a thermoplastic polymer is heated and injected into the mould such that it fills the flange-forming cavity. In step 508 the thermoplastic polymer is allowed to cool (which may typically take only a few seconds), and the connector is extracted.