FASTENER SYSTEM FOR IGNITION PREVENTION TRIGGERED BY A LIGHTNING STRIKE, STRUCTURE COMPRISING THE FASTENER SYSTEM, AND METHOD FOR MANUFACTURING THE STRUCTURE

Abstract

A fastener system for ignition prevention triggered by a lightning strike. The fastener has a fastener body and a fastener head, and a fastening member configured to be mounted on a portion of the fastener body, wherein the fastener and the fastening member are configured to fasten at least a first part and a second part between the fastener head and the fastening member, and the fastener comprises an electrically insulating material. A structure comprises the fastener system, the first part that faces an outside from where the lightning strike may hit the first part and the second part.

Claims

1. A fastener system for ignition prevention triggered by a lightning strike, the fastener system comprising: a fastener having a fastener body and a fastener head; and a fastening member configured to be mounted on a portion of the fastener body, wherein the fastener and the fastening member are configured to fasten at least a first part and a second part between the fastener head and the fastening member, and wherein the fastener comprises an electrically insulating material.

2. The fastener system according to claim 1, wherein the fastener comprises of at least one of glass, ceramics and a composite polymer material.

3. The fastener system according to claim 1, wherein the fastener comprises porcelain comprising at least one of clay, quartz and feldspar.

4. The fastener system according to claim 1, wherein the fastener comprises a composite polymer material and comprises a central rod made of fiber reinforced plastic and an outer shed made of silicone rubber or ethylene propylene diene monomer rubber.

5. The fastener system according to claim 1 further comprising a sealing material provided on at least a portion of the fastener body other than the portion of the fastener body where the fastening member is mounted on the fastener body.

6. The fastener system according to claim 5, wherein the fastener head is configured to protrude from a surface of the first part that is facing an outside from where a lightning strike may hit the first part, and the sealing material is only provided on a circumferential surface of the fastener body between the fastener head and the portion of the fastener body where the fastening member is mounted on the fastener body.

7. The fastener system according to claim 5, wherein the fastener head has a decreasing diameter in a direction towards the fastener body and is configured to be at least partly sunk in a surface of the first part that is facing an outside from where a lightning strike may hit the first part, and the sealing material is only provided on a circumferential surface of the fastener head that is facing the fastening member and a circumferential surface of the fastener body between the fastener head and the portion of the fastener body where the fastening member is mounted on the fastener body.

8. The fastener system according to claim 5, wherein the sealing material is a moisture-curing sealing material.

9. The fastener system according to claim 5, wherein at least one of the sealing material and the fastening member comprises an electrically insulating material.

10. The fastener system according to claim 1, wherein no sealing material is provided at the portion of the fastener body where the fastening member is mounted on the fastener body.

11. The fastener system according to claim 1, wherein a force-fit or a form-fit mounting of the fastening member on the portion of the fastener body is provided.

12. The fastener system according to claim 1, wherein the fastening member comprises an electrically insulating material.

13. A structure comprising: the fastener system according to claim 1, the first part that faces an outside from where a lightning strike may hit the first part, and the second part.

14. The structure according to claim 13, wherein at least one of the first part and the second part comprises an electrically insulating material, or wherein the second part is a part of a containment for ignitable substances, or both.

15. A method for manufacturing the structure according to claim 13, the method comprising providing the fastener body through the first and second parts; and providing the fastening member at a portion of the fastener body to fix the first and second parts between the fastening member and the fastener head.

16. The structure according to claim 13, wherein the second part is a part of a containment for ignitable substances.

17. The structure according to claim 16, wherein at least one of the first part and the second part comprises an electrically insulating material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Preferred embodiments of the invention will now be explained in more detail with reference to the appended schematic drawings, wherein

[0035] FIG. 1 shows a first embodiment of a fastener system and a composite structure;

[0036] FIG. 2 shows a second embodiment of a fastener system and a composite structure; and

[0037] FIG. 3 shows a flowchart of a method for manufacturing a composite structure of an aircraft.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0038] Although the embodiments according to FIGS. 1 to 3 explain the invention in more detail based on the examples of an aircraft and a composite structure, the present invention is not limited thereto, and the invention may also be realized in any other object that is deployed or located outside and may be hit by a lightning strike, and any other structure.

[0039] FIG. 1 shows a schematic drawing of a first embodiment of a fastener system and a composite structure for an aircraft comprising the fastener system.

[0040] In more detail, FIG. 1 depicts a first part 10 of an aircraft that faces the outside 15 of the aircraft, and a second part 20 of the aircraft that faces the inside 25 of the aircraft. For example, the first part 10 may be a surface panel of the aircraft and the second part 20 may be a part (e.g., a wall) of a containment for storing fuel. It also possible that at least one further part or layer is provided between the first and second parts 10, 20. Moreover, in FIG. 1, the first and second parts 10, 20 are shown as straight elements, however, the first and second parts 10, 20 may also have any other shape, e.g., be curved. In the schematic drawing of FIG. 1, a sidewall 27 of the containment is further exemplarily shown. Within the containment, an ignitable substance, e.g., fuel, is stored (not shown in FIG. 1). Parts 10, 20 and 27 may be electrically conductive or electrically insulating materials.

[0041] Within the first part 10 and the second part 20, throughholes are provided. In particular, the throughholes match each other and provide one common opening from the outside 15 to the inside 25 of the aircraft.

[0042] For fixing the first part 10 and the second part 20 together, a fastener system is foreseen. The fastener system comprises of a fastener comprising a fastener body 30 and a fastener head 35a, and a fastening member 40.

[0043] The fastener body 30 and the fastener head 35a are made as a one piece element. The fastener body 30 is stuck through the holes provided in the first and second parts 10, 20 from the outside 15 of the aircraft towards the inside 25 of the aircraft until the fastener head 35a abuts the outer surface of the first part 10. As shown in FIG. 1, the fastener head 35a protrudes from the outer surface of the part 10. The fastener head 35a may have any shape with an abutment surface 37 facing the fastening member 40 that enables a stable contact with the outer surface of the part 10. Preferably, the abutment surface 37 of the fastener head 35a has the same shape as the outer surface of the first part 10.

[0044] Before sticking the fastener body 30 through the holes, a sealant material 45 is provided on at least a part of the circumferential surface 50 of the fastener body 30 or in the holes of the parts 10, 20.

[0045] Thereafter, the fastening member 40 is mounted from the inside 25 on the fastener body 30 so that the first and second parts 10, 20 are fixed between the fastener head 35a and the fastening member 40. As can be seen from FIG. 1, when the fastening member 40 is mounted on the on the fastener body 30, a part of the fastener body 30 may protrude from the fastening member 40 towards the inside 25 of the aircraft. In particular, the fastening member 40 is mounted in such a manner on the fastener body 30 that fastener head 35a and the fastening member 40 provide a stable fixing of the first and second parts 10, 20 therebetween. The fastening member 40 may, e.g., be realized as a nut or a collar and may provide a force-fit or form-fit connection with the fastener body 30, i.e., the outer circumferential surface 50 of the fastener body 30.

[0046] The fastener body 30 and the fastener head 35a are made of an electrically insulating material. Preferably, the fastener body 30 and the fastener head 35a may comprise or may consist of at least one of glass and ceramics. Specifically, the fastener body 30 and the fastener head 35a may comprise or may consist of porcelain comprising at least one of clay, quartz and feldspar. The fastener body 30 and the fastener head 35a may also comprise or may consist of a composite polymer material. In this case, the fastener body 30 and the fastener head 35a comprises a central rod made of fiber reinforced plastic and an outer shed made of silicone rubber or ethylene propylene diene monomer rubber (not shown in FIG. 1).

[0047] When a lightning strike 55 hits the aircraft at the first part 10, an arc attachment point 60 of the lightning strike 45 may be located on the outer surface of the first part 10 at an outer end of the fastener head 35a. Due to the electrically insulating properties of the fastener body 30 and the fastener head 35a, these elements cannot act as a current path through the fastener system. Thus, an ignition of the ignitable substance provided within the containment 20, 27 can be prevented.

[0048] The fastening member 30 and/or the sealant material 45 may also be made of an electrically insulating material in order to further improve the lightning protection capabilities.

[0049] As can be seen from FIG. 1, the sealant material 45 is only provided in the holes between the abutment surface 37 of the fastener head 35a and the upper surface of the fastening member 40, i.e., between the outer circumferential surface 50 of the fastener body 30 and the inner surface of the holes of the parts 10 and 20. Thus, a tight sealing of the fastener body 30 between the parts 10 and 20 is ensured. Moreover, due to the electrically insulating property of the sealant material 45, the sealant material 45 may as well not act as a current path for the lightning strike 55.

[0050] Accordingly, the composite structure of the aircraft comprises of the fastener head 35a, the fastener body 30, the fastening member 40, and the first and second parts 10, 20. Additionally, the sealant material 45 may be provided in the holes.

[0051] FIG. 2 shows a schematic drawing of a second embodiment of a fastener system and a composite structure for an aircraft comprising the fastener system.

[0052] The second embodiment corresponds to the first embodiment. Differences between the first embodiment and the second embodiment are that the fastener of the second embodiment comprises a counter sunk head 35b instead of the fastener head 35a and that the hole provided in the first part 10 of the first embodiment differs from the hole provided in the first part 10 of the second embodiment. Moreover, contrary to the first embodiment, in the second embodiment, the sealant material 45 is additionally provided at the outer circumferential surface of the fastener head 35b, i.e., between the inner surface of the holes provided in the part 10 and the outer circumferential surface of the fastener head 35b. All other elements are the same so that these elements will not again be described for the second embodiment. In particular, the fastener head 35b of the second embodiment may comprise the same material as the fastener head 35a of the first embodiment.

[0053] In the second embodiment according to FIG. 2, the fastener head 35b is sunk into the first part 10 so that the outer surface of the first part 10 and the outer surface of the fastener head 35b provide a plane surface. It is also possible that the fastener head 35b is more deeply sunk into the first part 10, or even at least partly sunk into the second part 20. Due to the increasing diameter of the fastener head 35b in the direction opposite to the fastener body 30, when providing the fastener body 30 in the holes, the fastener head 35b may forcibly increase the diameter of the hole provided in the first part 10.

[0054] Similar to the first embodiment, in case a lightning strike 55 hits the aircraft at the first part 10, an arc attachment point 60 of the lightning strike 45 may be located on the outer surface of the first part 10 at an outer end of the fastener head 35b. Due to the electrically insulating properties of the fastener body 30 and the fastener head 35b, these elements cannot act as a current path through the fastener system. Similar, the sealant material 45 having electrically insulating properties does not act as a current path. Thus, an ignition of the ignitable substance provided within the containment 20, 27 can be prevented.

[0055] FIG. 3 shows a flowchart of a method 100 for manufacturing a composite structure of an aircraft. The method 100 may be employed for manufacturing the composite structure according to each of FIGS. 1 and 2. However, the method 100 may also be employed for manufacturing other composite or non-composite structures.

[0056] The method 100 comprises the steps of providing 115 the fastener body 30 through the first and second parts 10, 20 of the aircraft, and mounting 120 the fastening member 40 on a portion of the fastener body 30 to fix the first and second parts 10, 20 between the fastening member 40 and the fastener head 35a, 35b.

[0057] Additionally, the method 100 may comprise the initial step 110 of providing a moisture-curing sealing material 45 on the fastener body 30 or in holes provided in the first and second parts 10, 20 before the step 115 of providing the fastener body through the first and second parts 10, 20.

[0058] Finally, the method 100 may comprise the step 125 of air-drying the moisture-curing sealing material 45. To save further manufacturing costs, the air-drying may be provided without using any drying machinery.

[0059] Thus, a simple method for manufacturing a composite structure of an aircraft, which reliably protects the aircraft when being hit by a lightning strike, is provided.

[0060] As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.