COMPOSITE CONNECTORS AND METHODS OF MANUFACTURING THE SAME

Abstract

A method of manufacturing a connector for a fluid transfer conduit comprises: providing a first mould section comprising a hub-moulding portion which extends substantially parallel to a central axis C and a flange-moulding portion which extends from the hub-moulding portion at an angle to the central axis C; introducing fiber-reinforcement to the first mould section such that continuous circumferentially-oriented fiber-reinforcement lies in the hub-moulding portion, and continuous longitudinally-oriented fiber reinforcement extends from the hub-moulding portion into the flange-moulding portion; applying a second mould section over the first mould section to form a complete mould in which the fiber-reinforcement is confined; and introducing a polymer to the complete mould such that it permeates through the fiber-reinforcement to form a fiber-reinforced polymer connector; and extracting the connector from the mould.

Claims

1. A method of manufacturing a connector for a fluid transfer conduit, the method comprising: providing a first mould section comprising a hub-moulding portion which extends substantially parallel to a central axis and a flange-moulding portion which extends from the hub-moulding portion at an angle to the central axis; introducing fiber-reinforcement to the first mould section such that continuous circumferentially-oriented fiber-reinforcement lies in the hub-moulding portion, and continuous longitudinally-oriented fiber reinforcement extends from the hub-moulding portion into the flange-moulding portion; applying a second mould section over the first mould section to form a complete mould in which the fiber-reinforcement is confined; and introducing a polymer to the complete mould such that it permeates through the fiber-reinforcement to form a fiber-reinforced polymer connector; and extracting the connector from the mould.

2. The method of manufacturing a connector for a fluid transfer conduit as claimed in claim 1, wherein fiber introduced to the mould is dry fiber.

3. The method of manufacturing a connector for a fluid transfer conduit as claimed in claim 1, further comprising applying a tackifier to the dry fiber-reinforcement

4. The method of manufacturing a connector for a fluid transfer conduit as claimed claim 1, wherein the fiber-reinforcement comprises a woven tube.

5. The method of manufacturing a connector for a fluid transfer conduit as claimed in claim 1, wherein the flange-moulding portion comprises at least one raised boss, around which the fiber-reinforcement is diverted.

6. The method of manufacturing a connector for a fluid transfer conduit as claimed in claim 1, wherein the method comprises a resin transfer moulding process.

7. The method of manufacturing a connector for a fluid transfer conduit as claimed in claim 1, wherein the fiber-reinforcement comprises hoop overwound fiber-reinforcement.

8. A composite connector 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 continuous circumferentially-oriented fiber reinforcement; and wherein the connector comprises longitudinally-oriented fiber reinforcement which runs continuously from the hub portion into the flange portion.

9. The connector as claimed in claim 8, wherein there is little or no circumferentially oriented fiber reinforcement present in the flange portion

10. The connector as claimed in claim 8, wherein the flange portion comprises at least one through-hole defined by unbroken fiber reinforcement.

11. The connector as claimed in claim 8, wherein the continuous circumferentially-oriented fiber reinforcement in the hub portion extends at more than 80 from the central axis.

12. The connector as claimed in claim 8, comprising a thermosetting polymer matrix.

13. The connector as claimed in claim 8, wherein the hub portion further comprises longitudinal or helical fiber reinforcement.

14. The connector as claimed in claim 8, further comprising at least one non-fiber material additive.

15. A connection system comprising: the composite connector as claimed in claim 8; and a fiber-reinforced polymer fluid transfer conduit connected to the hub portion, wherein the composition and orientation of the fiber 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

DETAILED DESCRIPTION

[0061] FIG. 1 is a cross sectional view of the connection between a connector and a fluid transfer conduit;

[0062] FIG. 2 shows a connector for a fluid transfer conduit according to an example of the present disclosure;

[0063] FIG. 3 shows the connector for a fluid transfer conduit with a fluid transfer conduit installed therein; and

[0064] FIGS. 4-8 show various steps in a method of manufacturing a fluid transfer conduit according to an example of the present disclosure.

DETAILED DESCRIPTION

[0065] 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.

[0066] 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.

[0067] 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.

[0068] FIG. 2 is a perspective view of a 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.

[0069] The flange portion 108 comprises an annular, disc-like portion extending perpendicular to the central axis C.

[0070] The hub portion 106 comprises a thermoset resin matrix reinforced with both hoop (circumferential) fiber 110 and axial (longitudinal) fiber 112. The flange portion 108 contains no hoop-wound fiber but does comprise axial fiber 112 which extends continuously from the hub portion 106 into the flange portion 108.

[0071] The hoop fiber 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.

[0072] The axial fiber 112 that runs continuously from the hub portion 106 into the flange portion 108 strengthens the join between the hub portion 106 and the flange portion 108, increasing the resistance of the connector 102 to bending loads. The flange portion 108 does not contain any hoop-wound fiber, which saves weight and can aid manufacture.

[0073] The flange portion 108 comprises four through holes 114 (although only three are visible in the perspective view of FIG. 2) by which the connector 102 can be secured to another structure.

[0074] FIG. 3 shows a perspective view of the 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). Although not shown in this Figure, a second, similar, connector may connect the other end of the fuel pipe 104 to a second wing rib of the aircraft.

[0075] During flight, due to aerodynamic forces and/or temperature based expansion/contraction, the wing rib 118 (and thus the connector 102) moves relative to the 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 comprising the connection.

[0076] The composite fuel pipe 104 is constructed from fiber-reinforced polymer, and comprises a high proportion of continuous circumferentially oriented (hoop) fiber reinforcement 122. This provides the fuel pipe 104 with high hoop strength. In addition, the high proportion of hoop fiber-reinforcement 122 in the fuel pipe 104 means that its hoop coefficient of thermal expansion (hoop CTE) is dominated by that of the fiber-reinforcement 122, rather than the polymer matrix. The polymer from which the fuel pipe 104 is constructed is a thermoset polymer.

[0077] As mentioned above, the hub portion 106 also comprises a high proportion of hoop fiber-reinforcement 110 and a thermoset polymer. As such, the hoop CTE of the hub portion 106 is also dominated by that of the fiber-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.).

[0078] 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.

[0079] A method of manufacturing a composite connector according to the present disclosure will now be described with reference to FIGS. 4-8.

[0080] FIG. 4 shows how a woven fiber-reinforcement tube or sock may be manufactured. Multiple tows of dry fiber reinforcement 402 are woven onto a cylindrical mandrel 404 using a braiding tool (not shown) in conjunction with a braiding guide 406. The mandrel 404 extends along a central axis C and the woven fiber reinforcement 402 make an angle of roughly 45 to the central axis.

[0081] The mandrel 404 comprises a central portion 408 around which a male mould tool 410 is positioned. The male mould tool 410 comprises four raised bosses 412 (although only three are shown in FIG. 4) that extend parallel to the mandrel 404. The fiber reinforcement 402 extends over the male mould tool 410 and around the raised bosses 412 to form a woven sock 413 (also shown in FIGS. 5 and 6) with a tubular hub-forming portion 414 around the central portion 408 and an annular flange-forming portion 416 which extends radially outwards to the male mould tool 410. The flange-forming portion 416 comprises four holes corresponding to the four bosses 412. These will form bolt holes in the finished connector. If required, metallic inserts (not shown) may be pressed into these holes to provide a bearing surface.

[0082] Additional fiber reinforcement 402 is then filament wound at a high angle (e.g. >85) to the central axis C (i.e. in the hoop direction) over the hub-forming portion 414. This high angle reinforcement 402 provides the resultant hub portion with high hoop strength and can help to match the CTE of the connector with that of a fluid transfer conduit.

[0083] The woven sock 413, along with the mandrel 404 and the male mould tool 410 are then removed from the braiding tool. A tackifier 418 may be added (e.g. by spraying) to help hold the fiber reinforcement 402 of the woven sock 413 in position.

[0084] As shown in FIGS. 7 and 8, a female mould tool 420 is then placed over the mandrel 404 and the male mould tool 410 to form a complete mould 422 in which the woven sock 413 is enclosed. The mould 422 comprises an outlet 424 and two inlets 426 (additional, or fewer, outlets and inlets, although not shown in FIG. 7, may of course be used).

[0085] A vacuum infusion process is then utilised to form the woven sock 413 into a composite connector. A vacuum is applied to the outlet 424 and a thermosetting polymer 428 is injected into the mould 422 through the inlets 426. The polymer 428 is drawn through the mould 422 by the vacuum such that it permeates into the fiber reinforcement 402 of the woven sock 413. The polymer 428 is preferably a snap-cure polymer, such that curing times may be minimised.

[0086] Once the polymer 428 has fully infiltrated the woven sock 413, heat is applied to the mould 422 to cure the polymer 428 to form a composite connector 430. The mould 422 is then disassembled (i.e. by removing the female mould tool 420) to allow the composite connector 430 to be extracted.