AIRCRAFT STRUCTURE

Abstract

An aircraft structure including a first surface and a second surface. The first surface and the second surface are bonded together via a plurality of discrete adhesive sections arranged in a herringbone pattern or a support between the first surface and the second surface, wherein the support includes spaced apart ribs with discrete adhesive sections located between the spaced apart ribs.

Claims

1. An aircraft structure comprising: a first surface and a second surface, wherein the first surface and the second surface are bonded together via a plurality of discrete adhesive sections arranged in a herringbone pattern.

2. The aircraft structure according to claim 1, wherein adjacent discrete adhesive sections of the plurality of discrete adhesive sections are spaced apart from each other in a direction substantially parallel to the first surface.

3. The aircraft structure according to claim 2, comprising a support located between the adjacent discrete adhesive sections.

4. The aircraft structure according to claim 3, wherein the support is configured to provide a substantially fluid-tight seal between the adjacent discrete adhesive sections.

5. The aircraft structure according to claim 3, wherein the support comprises spaced apart ribs with the adjacent discrete adhesive sections located between the spaced apart ribs to form the herringbone pattern.

6. An aircraft structure comprising: a first surface; a second surface; a support between the first surface and the second surface, wherein the support comprises a plurality of spaced apart ribs, and discrete adhesive sections located between the spaced apart ribs.

7. The aircraft structure according to claim 6, wherein the support is bonded to at least one of the first surface and the second surface.

8. The aircraft structure according to claim 1, wherein the discrete adhesive sections have a substantially rectangular cross-sectional shape with a length to width ratio of at least 2:1.

9. The aircraft structure according to claim 1, wherein a first discrete adhesive section of the plurality of discrete adhesive sections is adjacent to a second discrete adhesive section of the plurality of discrete adhesive sections and a longest edge of the first discrete adhesive section is orthogonal to a longest edge of a second discrete adhesive section.

10. The aircraft structure according to claim 1, wherein a first discrete adhesive section of the plurality of discrete adhesive sections is adjacent to a second discrete adhesive section of the plurality of discrete adhesive sections and a longest edge of the first adhesive section is parallel to a longest edge of the second adhesive section, and wherein the first discrete adhesive section is offset from the second discrete adhesive section in a direction parallel to the longest edge of the first discrete adhesive section.

11. The aircraft structure according to claim 10, wherein a third discrete adhesive section of the plurality of discrete adhesive sections is adjacent to both the first and second discrete adhesive sections and the second and third discrete adhesive sections overlap a longest edge of the first discrete adhesive section.

12. A method of bonding a first surface to a second surface, the method comprising: providing a first surface and a second surface; forming a plurality of discrete adhesive sections in a herringbone pattern on the first surface; moving the second surface toward the first surface such that the discrete adhesive sections contact the first surface and the second surface; and curing the discrete adhesive sections to bond the first surface to the second surface.

13. The method according to claim 12, wherein the forming of the plurality of discrete adhesive sections in the herringbone pattern comprises using a support to guide placement of adhesive on the first surface in the herringbone pattern, wherein the support comprises a plurality of through-holes arranged in the herringbone pattern.

14. The method according to claim 13, wherein the forming of the plurality of discrete adhesive sections in the herringbone pattern comprises: loading the plurality of through-holes of the support with adhesive; and placing the support on the first surface such that the adhesive contacts the first surface.

15. The method according to claim 13, wherein the forming of the plurality of discrete adhesive sections comprises: placing the support on the first surface; and loading the plurality of through-holes of the support with adhesive when the support is on the first surface.

16. The method according to claim 14, further comprising removing the support from the first surface.

17. The method according to claim 16, wherein the removing of the support comprises dissolving the adhesive support.

18. The method according to claim 16, wherein the removing of the support from the first surface occurs before moving the second surface toward the first surface.

19. The method according to claim 16, wherein the removing of the support from the first surface occurs after curing the discrete adhesive sections.

20. An aircraft comprising the aircraft structure according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0043] FIG. 1 shows a schematic view of an aircraft;

[0044] FIG. 2 shows a schematic isometric view of an aircraft structure;

[0045] FIG. 3 shows a schematic view of a pattern of discrete adhesive sections;

[0046] FIG. 4 shows a schematic view of a part of the pattern of FIG. 3;

[0047] FIG. 5 shows a schematic partial cross-sectional view of the aircraft structure of FIG. 2;

[0048] FIG. 6 shows a schematic view of a support;

[0049] FIG. 7 shows a schematic isometric view of the support of FIG. 6;

[0050] FIG. 8 shows a schematic isometric view of an aircraft structure;

[0051] FIG. 9 shows a schematic partial cross-sectional view of the aircraft structure of FIG. 8;

[0052] FIG. 10 shows a flow diagram of a method of bonding a first surface to a second surface;

[0053] FIG. 11 shows a schematic view of a further aircraft structure;

[0054] FIG. 12 shows a schematic partial cross-sectional view of the aircraft structure of FIG. 11; and

[0055] FIGS. 13 to 15 show schematic views of further supports.

DETAILED DESCRIPTION

[0056] FIG. 1 shows a schematic isometric view of an aircraft 1. During assembly of the aircraft 1, various surfaces are bonded together to form aircraft structures. For example, surfaces are bonded together to form an aircraft structure which is a part of a wing 2 of the aircraft 1.

[0057] FIG. 2 shows a schematic view of the aircraft structure 10 which forms part of the wing 2 of the aircraft. The aircraft structure 10 comprises a first surface 11 and a second surface 12. FIG. 2 shows the first surface 11 and the second surface 12 before being bonded together. To bond the first surface 11 to the second surface 12, discrete adhesive sections 13 (including first 13a, second 13b, third 13c, fourth 13d, fifth 13e, sixth 13f and seventh 13g discrete adhesive sections) of adhesive are provided on the first surface 11. The first discrete adhesive section 13a and the second discrete adhesive section 13b form an inverted L-shape nested within an inverted L-shape formed by the third discrete adhesive section 13c and the fourth discrete adhesive section 13d. These inverted L-shapes of discrete adhesive sections 13 repeat across the first surface 11 to form the herringbone pattern.

[0058] The discrete adhesive sections 13 are substantially rectangular in shape with a length to width ratio of around 2:1, i.e., the length of the discrete adhesive sections 13 is approximately twice the width. The discrete adhesive sections are arranged in a herringbone pattern (shown in more detail in FIG. 3) and the first discrete adhesive section 13a is surrounded by the second, third, fourth, fifth, sixth and seventh discrete adhesive sections 13b, 13c, 13d, 13e, 13f, 13g. The first discrete adhesive section 13a is adjacent to the second discrete adhesive section 13b and the third discrete adhesive section 13c in a first direction (indicated by arrow X) and a length of the first discrete adhesive section 13a (i.e. the longest edge of the first discrete adhesive section 13a) is orthogonal to a length of the second discrete adhesive section 13b. The first discrete adhesive section 13a is also offset from the third discrete adhesive section 13c in a second direction (as indicated by arrow Y in FIG. 3).

[0059] In the herringbone pattern, adjacent discrete adhesive sections 13 are spaced apart from each other and each discrete adhesive section 13 is overlapped and/or surrounded by multiple adjacent discrete adhesive sections 13. FIG. 4 shows a zoomed in schematic view of a part of the herringbone pattern of FIG. 3. As shown in FIG. 4, an edge 15a of the first discrete adhesive section 13a is overlapped by an edge 15b of the second discrete adhesive section 13b and an edge 15c of the fifth discrete adhesive section 15e. As such, two discrete adhesive sections (i.e., the second and fifth discrete adhesive sections 13b, 13e) overlap the edge 15a of the first discrete adhesive section 13a.

[0060] The herringbone pattern may help to provide improved structural support should a crack occur in one of the discrete adhesive sections 13. For example, if a crack 14 were to form in the first discrete adhesive section 13a (as shown in FIG. 5), the load would be redistributed to the second through seventh discrete adhesive sections 13b-g surrounding the first discrete adhesive section 13a. This may help to provide redundancy in the event of a crack in one of the discrete adhesive sections. If a continuous bond line was used to bond the first surface 11 to the second surface 12, if the bond line cracked there would be no remaining bond between the first surface 11 and the second surface 12. This would then require immediate maintenance to repair. In the example of FIGS. 2 to 5, the first surface 11 and the second surface 12 remain bonded together even if a crack appears in a discrete adhesive section 13, which may allow more time before maintenance is required.

[0061] As the lengths of discrete adhesive sections 13 surrounding the first adhesive section 13a in the herringbone pattern do not all extend in the same direction (e.g., the length of the second discrete adhesive section 13b is orthogonal to the length of the first adhesive section 13a), this helps to provide improved load support in the event of a crack appearing in one of the discrete adhesive section 13. For example, if a crack appeared in the first adhesive section 13a and the load on the discrete adhesive sections 13 was in the second direction Y, the load would primarily be redistributed into the discrete adhesive sections 13 surrounding the first discrete adhesive section 13a which have lengths extending in the second direction Y (e.g., the third discrete adhesive section 13c and the fifth discrete adhesive section 13e). If the load on the discrete adhesive sections 13 was in the first direction X, the load would primarily be redistributed into the discrete adhesive sections 13 surrounding the first discrete adhesive section 13a which have lengths extending in the first direction X (e.g., the second discrete adhesive section 13b, the fourth discrete adhesive section 13d, the sixth discrete adhesive section 13f and the seventh discrete adhesive section 13g).

[0062] FIG. 5 shows a schematic cross-sectional side view of the aircraft structure 10 after the first surface 11 has been bonded to the second surface 12. As seen in FIG. 5, the first, fourth and sixth discrete adhesive sections 13a, 13d, 13f form a discontinuous bond line between the first surface 11 and the second surface 12. As such, if a crack 14 appears in the first discrete adhesive section 13a, the discontinuity between the first discrete adhesive section 13a and the fourth and sixth discrete adhesive sections 13d, 13f may help to prevent the crack from propagating to the fourth and/or sixth discrete adhesive sections 13d, 13f. As discussed above, the surrounding discrete adhesive sections 13 then support the load from the cracked first discrete adhesive section 13a.

[0063] A support 20, a part of which is shown in FIGS. 6 and 7, is used to create the herringbone pattern of discrete adhesive sections 13 on the first surface 11. The support 20 comprises ribs 21 which define through-holes 25 that extend through the support 20 between a first face 22 of the support 20 and a second face 23 of the support 20. Each of the through-holes 25 is defined by four walls 24 which extend between the first face 22 and the second face 23. To help prevent the adhesive from bonding to the walls 24, the walls 24 are coated in a non-stick material, such as polytetrafluoroethylene (PTFE). As shown in FIGS. 6 and 7, the through-holes 25 defined by the ribs 21 are arranged in the herringbone pattern. The support 20 is used as a stencil/mask when applying adhesive to the first surface 11, to create the herringbone pattern of discrete adhesive sections 13 on the first surface 11.

[0064] As illustrated in FIG. 8, in use the support 20 is placed on the first surface 11 such that the first face 22 of the support 20 is in contact with the first surface 11. The first face 22 comprises a self-adhesive material to secure the support 20 to the first surface 31 to hold the support 20 in a fixed position relative to the first surface 11. The adhesive is applied to the support 20 to fill the through-holes 25 such that the adhesive contacts the first surface 11. The support 20 is then removed from the first surface 11 to leave behind the discrete adhesive sections 13 in the herringbone pattern. Due to a viscosity of the discrete adhesive sections 13, the discrete adhesive sections 13 retain their shape in the herringbone pattern on the first surface 11 after the support 20 is removed from the first surface 11. The viscosity of the discrete adhesive sections 13 can be increased by partially curing the discrete adhesive sections 13 before removing the support 20 from the first surface 11.

[0065] The support 20 can either be removed from the first surface 11 before the second surface 12 is bonded to the first surface 11 (as shown in FIG. 5), or can remain on the first surface 11 until after the second surface 12 has been bonded to the first surface 11. FIG. 9 shows a partial cross-sectional view of the aircraft structure 10 when the support 20 is not removed before the second surface 12 is bonded to the first surface 11.

[0066] The support 20 provides a physical barrier between adjacent discrete adhesive sections 13 which may help to prevent the adjacent discrete adhesive sections 13 from seeping into, and bonding with, each other during or before curing. This helps to prevent a continuous bond line forming between the first surface 11 and the second surface 12. The support 20 also provides a substantially fluid-tight seal between the adjacent discrete adhesive sections 13 by substantially filling the space between the adjacent discrete adhesive sections 13. This may help to prevent or inhibit fluid flow past the discrete adhesive sections 13. This may be particularly advantageous when a fluid (e.g. fuel) is stored adjacent the first surface 11 and/or the second surface 12 as the substantially fluid-tight seal created by the support 20 may prevent the fluid from leaking through the discontinuous bond line.

[0067] The support 20 is also configured to control a thickness of the discrete adhesive sections 13 on the first surface 11 by reducing the amount of compression applied to the discrete adhesive sections 13 by relative movement of the first surface 11 and the second surface 12. During assembly, when the second surface 12 moves toward the first surface 11, a force is applied between the first surface 11 and the second surface 12 to ensure that the discrete adhesive sections 13 have sufficient contact with the first surface 11 and the second surface 12. However, this force may also compress the discrete adhesive sections 13, causing the discrete adhesive sections 13 to lose their shape, reduce in thickness and potentially seep into each other. To control the thickness of the discrete adhesive sections 13, the support 20 comprises a material which is resistant to being significantly deformed when a force is applied between the first surface 11 and the second surface 12. The amount that the support 20 will deform is known, allowing for control over the thickness of the discrete adhesive sections 13. This helps the support 20 to maintain a spacing between the first surface 11 and the second surface 12 to reduce the likelihood of the discrete adhesive sections 13 being compressed by the force applied between the first surface 11 and the second surface 12. A height of the support (i.e. the dimension of the support which extends from the first face 22 to the second face 23) can be selected/adjusted to result in a desired thickness of the discrete adhesive sections 13.

[0068] After the first surface 11 and the second surface 12 have been bonded together (as shown in FIG. 9), if the support 20 is no longer required it is removed from the aircraft structure 10. This may help to reduce the overall weight of the aircraft structure 10. To remove the support 20, a solvent is applied to the support 20 to dissolve the support 20. The solvent is selected such that it entirely dissolves the support 20 but does not affect the discrete adhesive sections 13.

[0069] FIG. 10 shows a flow diagram of a method 100 of bonding the first surface 11 to the second surface 12. The method 100 comprises providing 101 the first surface 11 and the second surface and forming 102 a plurality of discrete adhesive sections 13 in a herringbone pattern on the first surface 11. As discussed in relation to FIGS. 2 to 8, the discrete adhesive sections 13 are formed in the herringbone pattern using the support 20. The support 20 helps to guide the placement of the adhesive on the first surface 11 in the herringbone pattern.

[0070] To form the plurality of discrete adhesive sections 13 on the first surface 11, the support 20 is placed onto the first surface 11 such that the first face 22 of the support 20 abuts against the first surface 11. The adhesive is then applied to the support 20 and inserted into the through-holes 25 of the support 20 to load the through-holes 25 with the adhesive. As the through-holes 25 extend through the support 20, the adhesive also contacts the first surface 20. In some examples, the support 20 is placed on the first surface 11 multiple times in different positions to create the repeating herringbone pattern.

[0071] Once the adhesive has been applied to the support 20, the method 100 comprises removing 103 the support 20 from the first surface 11. The support 20 is removed by lifting the support 20 up and away from the first surface 11. This leaves behind the discrete adhesive sections 13 in the herringbone pattern on the first surface 11.

[0072] After the support 20 has been removed from the first surface, the method 100 comprises moving 104 the second surface 12 toward the first surface 11 such that the discrete adhesive sections 13 contact the first surface 11 and the second surface 12. A force is applied between the first surface 11 and the second surface 12 to move the first surface 11 and the surface 12 towards each other. This may help to ensure that the discrete adhesive sections 13 have sufficient contact with the first surface 11 and the second surface 12 to cause bonding.

[0073] The method 100 then comprises curing 105 the discrete adhesive sections 13 to bond the first surface 11 to the second surface 12. The first surface 11 and the second surface 12 are held in position relative to each other during curing to help to prevent misalignment. Curing 105 the discrete adhesive sections 13 is achieved by heating the first surface 11, second surface 12 and discrete adhesive sections 13 in an oven to a predefined temperature. Alternatively, other curing methods may be used, such a UV curing. Where UV curing is used, the support 20 comprises a UV transmissive that allows UV light to more easily pass through the support 20 to reach the discrete adhesive sections 13.

[0074] Although in the method 100 of FIG. 10, adhesive is inserted into the through-holes 25 of the support 20 when the support 20 is on the first surface, in some examples adhesive is inserted into the through-holes 25 before the support 20 is placed on the first surface 11. In this way, the support 20 is pre-impregnated with adhesive which may make it easier to apply adhesive to the first surface 11 and may reduce the likelihood of spilling adhesive compared to applying the adhesive when the support 20 is on the first surface 11. In some examples, the support 20 is provided pre-impregnated with adhesive. This may speed up the assembly process as adhesive is applied to the first surface 11 at the same time as applying the support 20 to the first surface.

[0075] In the method of FIG. 10, removing the support 20 from the first surface 11 occurs before the second surface 12 is bonded to the first surface 11. In some examples removing 103 the support from the first surface 11 occurs after the first surface 11 has been bonded to the second surface 12 or is omitted entirely.

[0076] FIG. 11 shows a schematic top view of an aircraft structure 30 comprising a first surface 31 and a support 40 provided on the first surface 31. The support 40 comprises a plurality of ribs 41 with discrete adhesive sections 33 located between the ribs 41. The support 40 helps to create a discontinuous pattern of discrete adhesive sections 33 on the first surface 31. Like in the example discussed in relation to FIGS. 2 to 9, the discrete adhesive sections 33 are rectangular in shape. In FIG. 11, the discrete adhesive sections 33 are not arranged in a herringbone pattern but are instead arranged in ordered rows. Lengths (i.e., the longest edge) of adjacent discrete adhesive sections 33 in a first direction (indicated by arrow A) are offset from each other in a second direction (indicated by arrow B), the first direction A and the second direction B are orthogonal to each other and are both being parallel to the first surface 31.

[0077] Although in FIG. 11 the discrete adhesive sections 33 are rectangular in shape, in some examples the discrete adhesive sections 33 have a different shape, such as a substantially circular, square or diamond shape. The discrete adhesive sections 33 may have a substantially square shape and be arranged on the first surface 31 in a checkerboard pattern where alternate rows of the checkerboard pattern are offset from each other (like the pattern shown in FIG. 11).

[0078] FIG. 12 shows a schematic cross-sectional side view of the aircraft structure 30 of FIG. 11 after the second surface 32 has been bonded to the first surface 31. As shown in FIG. 11, the support 40 is present between the first surface 31 and the second surface 32 after the second surface 32 is bonded to the first surface 31. The support 40 comprises a first face 42 which abuts the first surface 31.

[0079] FIGS. 13 to 15 show further examples of a support for use in bonding together surfaces. In FIG. 13, the support 50 comprises a heating element 51 which is disposed within the support 50. The heating element 51 is attached to a controller 52 which is configured to control operation of the heating element 51. The heating element 51 is configured to be activated during curing of the discrete adhesive sections 13, 33. The heat provided by the heating element 51 may help to speed up or otherwise control the curing process.

[0080] FIG. 14 shows a support 60 which is configured to be cut from a supply 61 of the support 60. The support 60 may be cut from the supply 61 to a shape which fits the surface to which it is being applied.

[0081] FIG. 15 shows a support 70 comprising a transfer sheet 70 onto which the herringbone pattern of discrete adhesive sections 13 is created. The discrete adhesive sections 13 are formed on the transfer sheet 70 remote from the first surface 11. In use, the support 70 is placed against the first surface 11 such that the discrete adhesive sections 13 in the herringbone pattern contact the first surface 11. The transfer sheet 71 is then peeled away from the first surface 11, leaving behind the discrete adhesive sections 13 in the herringbone pattern on the first surface 11.

[0082] The features of the supports of FIGS. 13 to 15 may also be used instead of, or in conjunction with, the features of the supports 20, 40 discussed in relation to FIGS. 6 to 9, 11 and 12. Although the above discussion focuses on bonding together surfaces to form an aircraft structure and the use of supports to do this, the concepts may equally be applied to bonding together surfaces of other structures. For example, the supports may be used in bonding together surfaces of marine vessels, racing cars or other vehicles.

[0083] It is noted that the term “or” as used herein is to be interpreted to mean “and/or”, unless expressly stated otherwise.