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 comprises: providing a tubular mandrel which extends substantially parallel to a central axis C; 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; curing the hub portion; 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 composite connector formed of a fibre-reinforced polymer for a fluid transfer conduit comprising: a hub portion comprising a tube which extends substantially parallel to a central axis; and a flange portion which extends from the hub portion at an angle to the central axis; wherein the hub portion comprises a thermosetting polymer reinforced with continuous circumferentially-oriented fibre reinforcement; wherein the flange portion comprises a polymer that is moulded onto the hub portion; and wherein the flange portion consists of non-reinforced polymer.

2. The composite connector as claimed in claim 1, wherein the flange portion comprises a thermosetting polymer.

3. The composite connector as claimed in claim 1, wherein the hub portion comprises at least one keying feature which provides a mechanical connection between the hub portion and the flange portion.

4. The composite connector as claimed in claim 1, wherein the flange portion comprises at least one through-hole.

5. The composite connector as claimed in claim 1, wherein the flange portion is substantially perpendicular to the central axis of the hub portion.

6. The composite connector as claimed in claim 1, wherein the continuous circumferentially-oriented fibre reinforcement extends at an angle of more than 80? to the central axis.

7. A connection system comprising: the composite connector as claimed in claim 1; 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 or the stiffness of the hub portion substantially matches that of the fluid transfer conduit.

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 shows 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) FIGS. 4A and 4B show various steps in a method of manufacturing a composite connector according to an example of the present disclosure; and

(6) FIG. 5 shows a schematic perspective view of a composite connector according to another 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.

(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 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.

(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 flange portion 108 which extends perpendicularly from an end of the hub portion 106. Through-holes 114 are formed in the flange portion 108.

(11) The hub portion 106 comprises a thermoset resin matrix reinforced with 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.

(12) FIG. 3 shows a perspective view of the composite connector 102 in use, connecting one end of a composite fuel pipe 104 to a wing spar 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 spar 118 via four bolts 120 (only three are visible in this Figure).

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

(14) 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.

(15) As mentioned above, the hub portion 106 also comprises a high proportion of hoop fibre-reinforcement 110. As such, the hoop CTE of the hub portion 106 is also dominated by that of the fibre-reinforcement 110. As a result, the hoop CTEs of the pipe 104 and the hub portion 106 are substantially equal and any 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 80? C.).

(16) 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.

(17) A method of manufacturing a connector for a fluid transfer conduit according to an example of the present disclosure will now be described with reference to FIGS. 4A and 4B.

(18) FIG. 4A shows a hub portion 106 of a composite connector for a fluid transfer conduit being constructed using a conventional filament winding process. Fibre reinforcement 402 (e.g. glass fibres) is passed through a thermosetting polymer resin (e.g. epoxy) bath (not shown) and wound under tension onto a cylindrical mandrel 404. The mandrel 404 rotates about a central axis C such that the fibre 402 is laid continuously onto the mandrel 404 in a helical pattern. The position at which the fibre 402 is provided to the mandrel 404, and the speed at which the mandrel 404 rotates, may be varied to control the orientation of the fibre reinforcement 402 in the resultant hub portion 106. As can be seen in FIG. 4a, in this case the fibre 402 is wound at a high angle (i.e. circumferentially) to provide the hub portion 106 with high hoop strength.

(19) Once all the required fibre reinforcement 402 has been wound onto the mandrel 404, the hub portion 106 may be (fully or partially) cured before being placed into a mould 406, as shown in FIG. 4B.

(20) The mould 406 into which the hub portion 106 is placed comprises a first portion 408 and a second portion 410 which, together with an outer surface 412 of the hub portion 106, define an annular cavity 412 which extends radially from the outer surface 414 of the hub portion 106.

(21) In this example, thermosetting polymer resin is pumped into the cavity 412 through one or more input channels (not shown). Heat is applied to the mould 406 to cure the resin and form a flange portion 108 moulded around the hub portion 106. In addition, the hub portion 106 may also be cured at this stage if it has not already been cured in a previous step. The mould portions 408, 410 are then removed and the finished composite connector 102 removed.

(22) Alternatively, the moulding step seen in FIG. 4B may be replaced by an injection moulding process, e.g. to mould a thermoplastic flange portion 108 over the hub portion 106.

(23) FIG. 5 shows an example of an alternative composite connector 502 with a flange portion 508 which is located partway along a hub portion 506.