Single-sided fastener, assemblies including single-sided fasteners, fuel tanks, and aircraft

Abstract

The invention provides a single-sided fastener, an assembly comprising a single-sided fastener, a fuel tank, and an aircraft, the single-sided fastener being configured to be installed in a hole of a given length. The single-sided fastener comprises a sleeve member configured to be deformed during installation of the single-sided fastener, a bolt member at least partially received within the sleeve member, and an insulation member fixedly arranged on the sleeve member. The sleeve member has a predetermined outer surface area arranged to be arranged within the hole after installation of the single-sided fastener. The insulation member and the sleeve member are mutually configured such that the insulation member is present on a first sub-area of the predetermined outer surface area and is not present on a second sub-area of the predetermined outer surface area. Each of the first sub-area and the second sub-area comprises the entire circumference of the sleeve member.

Description

Technical Field

[0001] This invention relates to single-sided fasteners, and to components, fuel tanks, and aircraft that include such single-sided fasteners. Background Technology

[0002] The trend of using composite materials to manufacture aircraft structural components is growing. In aircraft, metal fasteners are typically used to secure composite structural components to each other and / or to metal structural components. Composite materials used in aerospace structural components generally have much lower conductivity than metals, at least under normal aircraft operating conditions. If the current density exceeds the current-carrying capacity of the joint between the composite structural component and the metal fastener / structural component, the charge moving on and within the composite structural component can form an electric arc from the composite structural component to the adjacent metal fastener or structural component.

[0003] When lightning strikes such an aircraft, a large charge is placed on the composite structure. As the charge arcs from the composite structure to the metal fasteners or structural components, a very large amount of energy is consumed in a short period. The air surrounding the arc is heated by this energy, and the composite structure is also heated. The heating of the composite structure may be sufficient to cause small particles of the composite material to evaporate instantaneously. Alternatively or additionally, particles of the composite material and / or metal fasteners may become scorched and detach. The energy of the lightning strike is often sufficient to propel these particles as sparks a meter or more away from the arc location.

[0004] If such an electric arc discharge occurs in the fuel tank, there is a risk that a spark could ignite the fuel or any fuel vapors. Therefore, aircraft in which the fuel tank is at least partially formed by composite structural components must include mechanisms to prevent the fuel from igniting in the event of a lightning strike. Summary of the Invention

[0005] A first aspect of the invention provides a one-sided fastener configured to be installed in a hole of a given length. The one-sided fastener includes: a sleeve member configured to deform during installation of the one-sided fastener; a bolt member at least partially received within the sleeve member; and an insulating member fixedly disposed on the sleeve member. The sleeve member has a predetermined outer surface region configured to be disposed within the hole after installation of the one-sided fastener. The insulating member and the sleeve member are configured such that the insulating member is present in a first sub-region of the predetermined outer surface region and not present in a second sub-region of the predetermined outer surface region. Each of the first and second sub-regions includes the entire circumference of the sleeve member.

[0006] Optionally, the first sub-region is relatively closer to the tail end of the single-sided fastener and the second sub-region is relatively closer to the head end of the single-sided fastener.

[0007] Optionally, the diameter of the first sub-region is smaller than the diameter of the second sub-region by an amount substantially equal to the thickness of the insulating member.

[0008] Optionally, the diameter of the second sub-region is substantially equal to the outer diameter of the insulating member.

[0009] Optionally, the sleeve member has a deformable section configured to deform during installation of a single-sided fastener.

[0010] Optionally, the outer surface of the deformable section does not overlap with the predetermined outer surface area.

[0011] Optionally, the single-sided fastener is movable between a pre-installed configuration and a post-installed configuration, in which the sleeve member is undeformed and the tail end of the sleeve member has a first axial position relative to the bolt member; and in the post-installed configuration, the sleeve member is deformed and the tail end of the sleeve member has a different second axial position relative to the bolt member.

[0012] Optionally, the insulating component can be elastically deformed or plastically deformed.

[0013] Optionally, the predetermined outer surface region of the sleeve member includes a surface feature portion shaped to match the shape of the edge of the insulating member arranged on the predetermined outer surface region.

[0014] Optionally, the surface feature and the edge are configured to maintain close contact between the surface feature and the edge during and after the installation of the one-sided fastener.

[0015] Optionally, the surface features and edges include one or more of the following: a matching tapered portion, a matching stepped portion, and an interlocking feature configured to resist relative axial movement between the insulating member and the sleeve member.

[0016] Alternatively, the tail end of the insulating member is open.

[0017] Optionally, the tail end of the insulating member is closed, such that the tail ends of the bolt member and the sleeve member are enclosed within the insulating member.

[0018] Optionally, the bolt member has a head end on which a head is formed. The diameter of the head may be larger than the diameter of the rest of the bolt member.

[0019] Optionally, the top surface of the head of the sleeve member abuts against the lower surface of the head of the bolt member.

[0020] Optionally, the bolt member has a head end on which a head is formed; and the second sub-region is relatively closer to the head end of the bolt member than the first sub-region.

[0021] A second aspect of the present invention provides a component comprising: A structural member having a hole for connecting a first side of the structural member to a second side of the structural member; and According to the first aspect, the single-sided fastener is installed in the hole.

[0022] Optionally, the end portion of the insulating member closest to the head end of the single-sided fastener is disposed within the hole.

[0023] Optionally, the outer surface of the portion of the insulating member arranged inside the hole is in close contact with the hole, and a second sub-region of a predetermined outer surface area of ​​the sleeve member is in close contact with the hole.

[0024] Optionally, the structural component includes a first sub-structural component and a second sub-structural component fastened together by single-sided fasteners.

[0025] Optionally, the head of the single-sided fastener abuts against the first substructure and the tail of the single-sided fastener abuts against the second substructure, and the axial length of the first sub-region is less than the thickness of the second substructure.

[0026] Optionally, the structural component may include a composite material. Optionally, the structural component may also include a metallic material.

[0027] A third aspect of the invention provides a fuel tank comprising a single-sided fastener according to the first aspect and / or an assembly according to the second aspect.

[0028] An aircraft comprising a single-sided fastener according to a first aspect, a component according to a second aspect, or a fuel tank according to a third aspect. Attached Figure Description

[0029] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0030] Figure 1a and Figure 1b This is a schematic cross-section of the first example single-sided fastener according to the invention in a pre-installation configuration and a post-installation configuration;

[0031] Figure 2a and Figure 2b This is a schematic cross-section of an example matching sleeve member and an insulating member feature suitable for an example single-sided fastener according to the present invention;

[0032] Figure 3a and Figure 3b This is a schematic cross-section of a second example single-sided fastener according to the invention in a pre-installation configuration and a post-installation configuration;

[0033] Figure 4 This is a schematic cross-section of an example fuel tank according to the invention; and

[0034] Figure 5 This is a perspective view of an example aircraft according to the present invention. Detailed Implementation

[0035] The examples of the invention described in the following discussion relate to single-sided fasteners. Each single-sided fastener according to the invention is configured to be installed in a hole of a given length, and each single-sided fastener has a sleeve member, a bolt member, and an insulating member. The sleeve member is configured to deform during installation of the single-sided fastener and has a predetermined outer surface area, which is arranged within the hole after the single-sided fastener has been installed. The bolt member is at least partially arranged within the sleeve member, and the insulating member is fixedly arranged on the sleeve member. The insulating member and the sleeve member are configured such that the insulating member is present in a first sub-region of the predetermined outer surface area and not present in a second sub-region of the predetermined outer surface area. Each of the first and second sub-regions includes the entire circumference of the sleeve member.

[0036] Sparks between fasteners and structural components—on which the fasteners are typically mounted—usually occur below the nut (or below the formed tail in the case of single-sided fasteners). Conventionally, such sparks are prevented by insulating the fastener-structural component joint with a coating or other insulating material applied to the structural component. However, it has been found that this coating is frequently damaged during fastener installation, necessitating inspection of each fastener location in the fuel vapor zone of the aircraft after installation. This inspection is time-consuming and often impossible in applications using single-sided fasteners (typically because the back of the structural component with the fastener mounted is inaccessible, both for manipulating the nut and for inspecting the fastener tail and surrounding structure). The single-sided fastener according to the invention advantageously provides a solution for reliably ensuring an intact insulating barrier between the formed tail of the fastener and the structural component after installation, thereby preventing sparks.

[0037] Specifically, in the post-installation configuration of the example fastener according to the invention, the insulating member completely covers the area of ​​the sleeve member that would otherwise contact the surface of the structural member where the fastener is already installed. This prevents contact between adjacent surfaces of the sleeve member and the structural member, thus preventing sparks from forming between the tail of the fastener and the structural member in the event of a lightning strike. The insulating member is robust enough to ensure its integrity is maintained during the fastener installation process, thereby eliminating the need to inspect the tail of the fastener. Furthermore, the need to apply an insulating coating to the structural member is also eliminated. Advantageously, the fastener according to the invention is configured such that the insulating member is ultimately in the desired position due to the normal installation process of the fastener, thus requiring no further operations during the assembly process.

[0038] Figure 1a and Figure 1b This is a cross-section of an example single-sided fastener 10 according to the present invention. The single-sided fastener 10 can be configured in a pre-installation configuration (such as...). Figure 1a (as shown) and the installed configuration (such as) Figure 1b The fastener 10 shown in the figure can move between the two sides. Examples of suitable single-sided fasteners—on which insulating members can be disposed to form a single-sided fastener according to the invention—include: OSI-Bolt(R) manufactured by Monogram Aerospace Fasteners, Composi-Lok(R) manufactured by Monogram Aerospace Fasteners, Radial-Lok(R) manufactured by Monogram Aerospace Fasteners, Ergotech(R) manufactured by Arconic, and Optiblind(TM) manufactured by Lisi Aerospace. Although the fastener 10 shown is a head-protruding fastener, other examples of single-sided fasteners 10 with countersunk heads are also possible.

[0039] exist Figure 1bIn this structure, fasteners 10 are installed in holes formed in a structural member consisting of a first sub-structural member 14 and a second sub-structural member 15. The combination formed by the single-sided fasteners 10 installed on the sub-structural members 14 and 15 can be considered as an assembly. The holes have an axial length L, and the fasteners 10 are configured to be installed in holes having a specific axial length L equal to the thickness of the structural member. The first sub-structural member 14 and the second sub-structural member 15 are held together by the single-sided fasteners 10. Both the first structural member 14 and the second structural member 15 can be formed of a composite material, or both can be formed of a metallic material, or one of the first structural member 14 and the second structural member 15 can be formed of a composite material and the other of the first structural member 14 and the second structural member 15 can be formed of a metallic material. In some examples, the first structural member 14 and the second structural member 15 are aircraft structural members. For example, the first structural member 14 can be a wing canopy and the second structural member 15 can be a wing spars.

[0040] Fastener 10 includes a bolt member 11, a sleeve member 12, and an insulating member 13. Bolt member 11 and sleeve member 12 can be formed of any suitable material having material properties suitable for resisting the operational loads expected to be borne by the one-sided fastener 10. The material of sleeve member 12 (or at least a deformable portion of sleeve member) must be able to deform during fastener 10 installation in such a way as described above.

[0041] Bolt member 11 is at least partially received within sleeve member 12. Bolt member 11 has a head end 111 on which a head is formed. The diameter of the head is larger than the diameter of the rest of bolt member 11. The end of bolt member 11 opposite to the head end is referred to as tail end 112. Sleeve member 12 can also be considered to have a head end (i.e., the end of sleeve member closest to the head of bolt member 11) and a tail end (i.e., the end of sleeve member closest to the tail end of bolt member 11). In the illustrated example, sleeve member 12 includes a head 121 at the head end. The diameter of head 121 of sleeve member 12 is larger than the diameter of the rest of sleeve member 12, and the diameter of head 121 of sleeve member 12 is larger than the diameter of a hole into which a single-sided fastener 10 is configured to be installed.

[0042] Note that when the sleeve member is in an undeformed state, the bolt member 11 is at least partially received within the sleeve member 12, such as... Figure 1a As shown in the image.

[0043] In the illustrated example, threads exist on the circumferential surface at and / or near the tail end 112 of the bolt member 11. The threads on the bolt member 11 engage with corresponding threads on the inner surface of the tail end of the sleeve member 12. The threaded engagement between the bolt member 11 and the sleeve member 12 serves to drive relative axial movement between the bolt member 11 and the sleeve member 12 in response to relative rotational movement. It should be noted that other one-sided fasteners according to the invention may not include the threaded engagement between the bolt member and the sleeve member, and alternatively, some other mechanisms may be provided for driving the relative axial movement of the bolt member and the sleeve member. For example, the bolt member 11 may be configured to be pulled upward by an externally applied tension during fastener 10 installation, while the sleeve member 12 remains fixed. In other examples, this relative axial movement may be driven in some other way, such as by rotating or pulling the sleeve member 12.

[0044] Sleeve member 12 has a predetermined outer surface area 123 (as shown in the figure) Figure 1a Corresponding to the outer surface of the shaded portion of the sleeve member 12 shown, the predetermined outer surface region 123 is configured to be arranged within the hole after the one-sided fastener 10 is installed. The predetermined outer surface region 123 extends around the entire circumference of the sleeve member 12, such that the predetermined outer surface region 123 forms a closed loop. The axial length of the predetermined outer surface region is equal to or slightly less than the length L of the hole into which the one-sided fastener 10 is configured to be installed. The predetermined outer surface region 123 is positioned to ensure that it will be arranged within the hole after the fastener 10 is installed. In particular, the predetermined outer surface region extends from immediately below the head 121 of the sleeve member 12 (according to...) Figure 1a and Figure 1b (The orientation shown in the diagram) begins. The importance of the predetermined outer surface region 123 will become apparent from the following detailed discussion of the insulating member 13.

[0045] The sleeve member 12 is configured to deform during the installation of a single-sided fastener. Specifically, the sleeve member is configured to deform from... Figure 1a The undeformed shape shown transitions to Figure 1b The deformable shape is shown in the illustration. In the illustrated example, the sleeve member 12 includes a deformable segment 122. The maximum diameter of the deformable shape of the deformable segment 122 of the sleeve member 12 is larger than the maximum diameter of the undeformed shape of the deformable segment 122. In some examples, the maximum diameter of the deformable shape of the deformable segment 122 is greater than or equal to the diameter of the head 121 of the sleeve member 12. Both the diameter of the head 121 and the maximum diameter of the deformable shape of the deformable segment 122 are larger than the diameter of the hole for mounting the fastener 10.

[0046] The deformable segment 122 begins immediately below the predetermined outer surface region 123 and extends toward the tail end of the sleeve member 12. The outer surface of the deformable segment 122 does not overlap with the predetermined outer surface region 123. The axial distance between the head 121 and the head end of the deformable segment 122 can be substantially equal to L. The deformable segment 122 terminates above the threaded portion of the sleeve member 12. The axial length of the deformable segment 122 can be selected according to the specific intended application of the one-sided fastener 10. For example, a relatively long deformable segment 122 can result in a deformable shape with a relatively large diameter, but with relatively low strength compared to a relatively short deformable segment 122. The deformable segment 122 may include weakened regions at one or more selected locations (e.g., in...). Figure 1a and Figure 1b The positions of the dashed lines in the diagram are used to ensure that buckling of the sleeve member 12 occurs in a predictable manner at these locations. All or part of the deformable section 122 may have different material properties than the rest of the sleeve member 12. For example, all or part of the deformable section 122 may be less brittle than the rest of the sleeve member 12.

[0047] An insulating member 13 is fixedly arranged on a sleeve member 12. Specifically, the insulating member 13 is arranged circumferentially around at least a portion of the sleeve member 12. Relative movement between the insulating member 13 and the sleeve member 12 is substantially prevented by using a fixing technique to fix the insulating member 13 to the sleeve member 12. The axial length of the insulating member 13 is less than the axial length of the sleeve member 12. In the illustrated example, the insulating member 13 is tubular and the sleeve member 12 extends from both ends of the insulating member 13. In other examples (such as those discussed below)... Figure 3a and Figure 3b (Examples), the insulating member 13 can take different forms. In a pre-installation configuration, the outer diameter of the insulating member 13 is less than or equal to the diameter of the hole into which the fastener 10 is configured to be installed. The outer diameter of the insulating member 13 in the pre-installation configuration can advantageously be slightly smaller than the diameter of the hole to allow easy insertion of the single-sided fastener 10 into the hole. However, preferably, the outer surface of the portion of the insulating member 13 that is disposed within the hole after the fastener 10 is installed is in close contact with the hole after such installation. In some examples, the outer surface of the insulating member 13 can be a low-friction surface to facilitate insertion of the fastener 10 into the hole.

[0048] The insulating member 13 is deformable to accommodate deformation of the sleeve member 12 that occurs during the installation of the fastener 10. In some examples, the insulating member 13 is elastically deformable. In other examples, the insulating member 13 is plastically deformable. In some examples, the length of the insulating member 13 in the post-installation configuration may be greater than its length in the pre-installation configuration due to stretching during the installation process. The insulating member 13 can be formed of any suitable electrical insulating material. For example, the insulating member 13 may include a polymer material. The insulating member 13 may include a reinforcing polymer material. The insulating member 13 may include a thermoplastic material. Suitable materials may include nylon, acrylonitrile butadiene styrene (ABS), polyethylene, thermoplastic elastomers (TPE or TPE) or other polymer materials, optionally a fabric-reinforced polymer material. The material of the insulating member 13 is selected such that the insulating member 13 is strong enough to maintain the structural integrity of the insulating member 13 during the installation and subsequent operation of the fastener 10, and is also electrically insulating enough to prevent sparks from being generated between the sleeve member 12 and the second substructure member 15 in the event of a lightning strike.

[0049] The insulating member 13 can be secured to the sleeve member 12 using any suitable fixing or retaining mechanism. In the illustrated example, the insulating member 13 is secured to the sleeve member 12 by friction via an interference fit between the insulating member 13 and the sleeve member 12. The interference fit generates sufficient friction to substantially prevent relative movement between the insulating member 13 and the sleeve member 12 during the installation and subsequent operation of the single-sided fastener 10. During deformation of the sleeve member 12, a small amount of local slippage may occur between one or more portions of the insulating member 13 and the abutting portion of the sleeve member 12; however, the overall relative axial position of the insulating member 13 and the sleeve member 12 should not change during the deformation process. In some examples, the insulating member 13 may be coupled to the sleeve member 12. Alternatively or additionally, the insulating member 13 may be secured to the sleeve member 12 by mechanical interlocking, as will be referred to below. Figure 2b The following are described. Suitable mechanisms for securing the insulating member 13 to the sleeve member 12 include (but are not limited to) interference fit, adhesive bonding, snap-fit ​​joint, thermoplastic welding, fasteners or other mechanical means.

[0050] The insulating member 13 and the sleeve member 12 are configured such that the insulating member 13 is present on a first sub-region r1 of a predetermined outer surface region 123, but not on a second sub-region r2 of the predetermined outer surface region 123. This is the case in both the pre-installation configuration and the post-installation configuration of the single-sided fastener 10. Each of the first sub-region r1 and the second sub-region r2 comprises the entire circumference of the sleeve member 12. The first sub-region r1 is relatively closer to the tail end of the single-sided fastener 10, and the second sub-region r2 is relatively closer to the head end of the single-sided fastener 10. The second sub-region r2 is also closer to the head end 111 of the bolt member than the first sub-region r1. Therefore, the second sub-region r2 is located between the head end 111 of the bolt member and the first sub-region r1.

[0051] When the fastener 10 is installed in the hole, the first sub-region r1 is adjacent only to the second sub-structure 15, and the second sub-region r2 is adjacent to both the first sub-structure 14 and the second sub-structure 15. This means that the sleeve member 12 is in direct contact with both the first sub-structure 14 and the second sub-structure 15. In examples where the structure includes two (or more) sub-structures, it is important that the sleeve member 12 is in direct and close contact with each of the sub-structures. Therefore, the axial length of the first sub-region r1 is always less than the thickness of the sub-structure abutting against the formed tail of the fastener (i.e., according to...). Figure 1b The most basic structural component with the orientation shown.

[0052] The diameter D2 of the second sub-region r2 is substantially equal to the outer diameter of the insulating member 13, and also substantially equal to the diameter of the hole in which the single-sided fastener 10 is configured to be installed. After the fastener 10 is installed in the hole, the second sub-region is thus in close contact with the hole. The diameter D1 of the first sub-region r1 is smaller than the diameter D2 of the second sub-region r2 by an amount substantially equal to the thickness t of the insulating member 13. In particular, the minimum diameter of the first sub-region r1 is smaller than the diameter of the second sub-region r2 by an amount substantially equal to the thickness t of the insulating member 13. In the illustrated example, the first sub-region r1 includes a tapered portion. The diameter of the first sub-region r1 continuously increases from the aforementioned minimum diameter to a maximum diameter along the axial length of the tapered portion, which is equal to the diameter of the second sub-region r2. The angle of the tapered portion (i.e., the rate of change of the diameter along the tapered portion) can be greater than or less than the angle of the tapered portion. Figure 1a and Figure 1bThe angle of the tapered portion is shown. The edge of the insulating member 13 arranged on the predetermined outer surface region 123 (i.e., the edge of the insulating member 13 closest to the head end of the fastener 10) is correspondingly and relatively tapered, such that there is no gap between this edge of the insulating member 13 and the tapered portion of the sleeve member 12. It is desirable to avoid air gaps in the hole, as any such gap could potentially cause sparks in the event of a lightning strike to the fastener 10 or to a structural member on which the fastener 10 is mounted. Providing a tapered or chamfered profile at the point where the edge of the insulating member 13 abuts against the sleeve member 12 can help avoid air gaps at this location in the hole.

[0053] More generally, the predetermined outer surface region 123 of the sleeve member 12 includes surface features shaped to match the shape of the edge of the insulating member 13 arranged on the predetermined outer surface region 123. Figure 1a and Figure 1b In a specific example, the surface feature is a tapered portion. However, various other forms of surface features according to the invention are also possible. Figure 2a and Figure 2b Two possible configurations of this alternative surface feature are shown. In each example, the surface feature on the sleeve member 12 and the corresponding edge of the insulating member 13 are configured to maintain close contact between the surface feature on the sleeve member 12 and the corresponding edge of the insulating member 13 during and after installation of the one-sided fastener. In some examples, the surface feature and the corresponding edge are configured to resist relative axial and / or rotational movement between the sleeve member 12 and the insulating member 13.

[0054] Figure 2a and Figure 2b The figures show partial cross-sections of two different example single-sided fasteners 20a and 20b according to the present invention. Each fastener 20a and 20b includes a bolt member, a sleeve member, and an insulating member, and each of the bolt member, sleeve member, and insulating member is identical to the corresponding member of the example single-sided fastener 10, except for the differences explicitly described below. Figure 2a and Figure 2b The shown with Figure 1a and Figure 1b The same features shown have been given the same reference numerals and will not be described further. Figure 2a and Figure 2b Each of the visible fastener segments includes a portion of a predetermined outer surface region of the corresponding sleeve member and a matching edge of the corresponding insulating member, the predetermined outer surface having surface features configured to match the edge of the corresponding insulating member. The distinguishing features of the example single-sided fasteners 20a and 20b can be applied to any other single-sided fastener according to the invention.

[0055] Figure 2a An example single-sided fastener 20a has a sleeve member 22 having a predetermined outer surface region 223 on which a surface feature 224 is present. In this particular example, the surface feature 224 is a stepped portion. That is, the diameter of the predetermined outer surface region abruptly changes from a minimum diameter (the diameter of sub-region r1) to a maximum diameter (the diameter of sub-region r2) at the location of the stepped portion 224. The difference between the minimum and maximum diameters is equal to the thickness of the insulating member 23 of the fastener 20a. The end face of the stepped portion 224 is substantially perpendicular to the outer surface of the sleeve member 22. The insulating member 23 is arranged on the predetermined outer surface region 223 and... Figure 2a The visible edge matches the step 224 because the thickness of the edge is equal to the height of the step 224 and the end face of the edge is substantially perpendicular to the outer surface of the insulating member 23 (and perpendicular to the outer surface of the sleeve member 22). The step 224 extends continuously around the sleeve member 22, forming a complete circumference. In some examples, the axial position of the step can vary around the circumference of the fastener 20a, for example, creating a serrated or wavy boundary between the first sub-region r1 and the second sub-region r2. This arrangement can advantageously resist relative rotation between the sleeve member 22 and the insulating member 23. The same principle can also be applied to the tapered surface features and edges of the example fastener 30.

[0056] In addition to the sleeve member 22 and the insulating member 23, it also includes interlocking features 225 and 235 configured to resist relative axial movement between the insulating member 23 and the sleeve member 13. Figure 2b Example single-sided fastener 20b and Figure 2a The example single-sided fastener 20a is the same. The interlocking feature 225 on the sleeve member 22 is arranged on the first sub-region r1 of the predetermined outer surface region 223, and the interlocking feature 235 on the insulating member 23 is arranged on the inner surface of the insulating member at a position adjacent to the interlocking feature 225 on the sleeve member.

[0057] In the illustrated example, the sleeve member interlocking feature 225 is a circumferential protrusion. The height of the protrusion 225 is less than the thickness of the insulating member 13. The height of the illustrated protrusion 225 is approximately equal to half the thickness of the insulating member 23. The insulating member interlocking feature 235 is a circumferential recess, the depth of which is substantially equal to the height of the protrusion 225. The shape of the recess 235 matches the shape of the protrusion, such that the protrusion 225 can be received in the recess 235 without any air gap between the protrusion 225 and the recess 235. In the illustrated example, both the protrusion 225 and the recess 235 have a square profile, but any other matching profile shape is also possible. In some examples, multiple corresponding protrusions 225 and recesses 235 can be arranged around the circumference of the fastener 20b, wherein each matching protrusion-recess pair extends only partially around the circumference. This arrangement can advantageously provide improved resistance to relative rotation of the insulating member 23 and the sleeve member 22.

[0058] Figure 3a and Figure 3b An alternative configuration of the single-sided fastener according to the invention is illustrated. Figure 3a In the pre-installation configuration and in Figure 3b An example single-sided fastener 30 is shown in the installed configuration (mounted in a hole formed in a structural member consisting of two sub-structural members 14 and 15). Except for the differences explicitly described below, the single-sided fastener 30 is similar to... Figure 1a and Figure 1b The example single-sided fastener 10 is substantially the same. Features of the single-sided fastener 30 that are identical to those of the single-sided fastener 10 have been given the same reference numerals and will not be described further. The distinguishing features of the example single-sided fastener 30 can be applied to any other single-sided fastener according to the invention.

[0059] The difference between the single-sided fastener 30 and the single-sided fastener 10 is that the insulating member 33 of the single-sided fastener 30 has a different configuration than the insulating member 13 (but the material properties are the same). Specifically, the insulating member 33 is in the form of a cap. That is, the tail end of the insulating member 33 is closed, such that the tail ends of the bolt member 11 and the sleeve member 12 are each enclosed within the insulating member 33. The axial length of the insulating member 33 is also greater than the axial length of the tubular insulating member 13, so as to include the tail end of the bolt member 11. (See from...) Figure 3aAs can be seen, in the pre-installed configuration of fastener 30, insulating member 33 extends downward from the tail end of bolt member 11 by a certain distance. Specifically, a gap exists between the base of insulating member 13 and the base of bolt member 11. The axial length of this gap is greater than or equal to the expected relative axial displacement between the tail end of sleeve member 12 and bolt member 11 during fastener 30 installation, and this gap is provided to accommodate relative axial movement between the tail ends of sleeve member 12 and bolt member 11 during fastener 30 installation. Other examples are also possible, wherein the material of insulating member 33 is sufficiently elastic such that relative axial movement between the tail ends of bolt member 11 and sleeve member 12 can be partially or fully accommodated by the extension of insulating member 13. In such an example, the axial length of insulating member 33 may be less than the expected relative axial displacement between the tail end of sleeve member 12 and bolt member 11 during fastener 30 installation.

[0060] Now refer to Figure 1a and Figure 1b Example fastener 10 illustrates the installation of a single-sided fastener according to the invention. However, the same installation process applies to all single-sided fasteners according to the invention.

[0061] To install the single-sided fastener 10 into the hole, the fastener 10 is inserted into the hole in a pre-installed configuration until the head 121 of the sleeve member 12 abuts against the outer surface of the structure forming the hole. During the installation of the single-sided fastener 10, rotation of the sleeve member 12 relative to the structure forming the hole is prevented substantially by any suitable means. Since the insulating member 13 is fixed to the sleeve member 12, rotation of the insulating member is also prevented during the installation of the fastener 10. Meanwhile, the bolt member 11 rotates relative to the structure and relative to the sleeve member 12 (e.g., using an installation tool such as a wrench). The head 111 of the bolt member 11 and the head 121 of the sleeve member 12 may each include features configured to engage with an installation tool to facilitate or prevent rotation of the respective member.

[0062] The rotation direction of bolt member 11 is selected based on the thread configuration. Assuming a standard thread, bolt member 11 rotates clockwise when fastener 10 is installed. The relative rotation of bolt member 11 and sleeve member 12 forces the tail end of sleeve member 12 toward the head end of fastener 10. When bolt member 11 rotates, the head end of sleeve member 12 cannot move relative to bolt member 11 because the upper surface of head 121 of sleeve member 12 abuts against the lower surface of head 111 of bolt member 11. Therefore, forcing the tail end of sleeve member 12 toward the head end of fastener 10 causes axial compression of sleeve member 12. Sleeve member 12 is configured to deform in response to axial compression. Figure 1bThe deformed shape is shown. The threads and heads 111, 121 are configured such that sufficient torque can be applied to produce a shape sufficient to deform the sleeve member 12. Figure 1b The axial compressive force of the deformed shape shown.

[0063] A specific example of a single-sided fastener 10 includes a deformable section 122, which is configured to deform in a predetermined manner in response to axial compression as described above. Specifically, the compressive force generated by rotating the bolt member 11 relative to the sleeve member 12 causes the deformable section 122 of the sleeve member 12 to buckle radially outward. Figure 1b The shape shown.

[0064] When the sleeve member 12 deforms, the tail end of the sleeve member 12 moves axially toward the head end of the bolt member 11 relative to the bolt member 11. The tail end of the insulating member 13 moves together with the tail end of the sleeve member 12, and the insulating member 13 deforms together with the sleeve member 12. In the pre-installation configuration, the tail end of the sleeve member 12 has a first axial position relative to the bolt member 11. In particular, the tail end of the sleeve member 12 is relatively far from the head 111 of the bolt member 11 (compared to the post-installation configuration). In the post-installation configuration, the tail end of the sleeve member 12 has a different second axial position relative to the bolt member 11. In particular, the tail end of the sleeve member 12 is relatively closer to the head 111 of the bolt member 11.

[0065] Once the sleeve member 12 has fully deformed, rotation of the bolt member 11 stops. In some examples, the fastener 10 may include a feature that, once full deformation has been achieved (e.g., the head 111 can be sheared off from the shank of the bolt member 11 when a predetermined torque is reached), prevents further relative rotation between the bolt member 11 and the sleeve member 12. Once the sleeve member 12 has fully deformed, the fastener 10 is in a state of... Figure 1b The installed configuration is shown. The structural member forming the hole is then clamped between the head 121 and the deformable section 122 of the sleeve member 12. Figure 1b In the case of a structural member as shown, which comprises multiple sub-structural members, these sub-structural members are thus held together to prevent axial separation. Figure 1b As can be seen, direct contact between the sleeve member 12 and the lower surface of the structural member is prevented because an insulating member 13 is arranged between the sleeve member 12 and the structural member. It will be understood that this arrangement is a necessary consequence of the configuration of the single-sided fastener 10, and no special effort or care is required during the installation of the fastener 10 to ensure that the insulating member 13 is arranged between the sleeve member 12 and the structural member.

[0066] Figure 4This is a cross-section of the fuel tank 400. The fuel tank 400 includes a first substructure 404a and a second substructure 404b, which are fastened together by a single-sided fastener 40 according to the invention. The fuel tank 400 is shown schematically and not to scale. In particular, for ease of description, the fastener 40 is shown significantly larger than it would be in a real-world application compared to the rest of the fuel tank.

[0067] The single-sided fastener 40 shown in the figure and Figures 1a to 1b The example fastener 10 has the same design, but the single-sided fastener 40 can be any single-sided fastener according to the invention. The first sub-strument 404a is the first end of the integral fuel tank wall component 404, and the second sub-strument 404b is the second end of the integral fuel tank wall component. However, other examples are also possible, in which the first sub-strument 404a and the second sub-strument 404b are included in separate components. The first sub-strument 404a and the second sub-strument 404b can have any of the features described in the examples of the first sub-strument 14 and the second sub-strument 15 above. The fuel tank wall component 404 is configured such that when the first sub-strument 404a and the second sub-strument 404b are fastened together, the fuel tank wall component 404 defines an enclosed space 406 suitable for storing fuel. The enclosed space 406 can be referred to as a fuel-containing space (although in some operating states of the fuel tank, no fuel may actually be contained in the enclosed space 406). In some examples, the first substructure 404a and the second substructure 404b can be fastened together by a plurality of single-sided fasteners 40 according to the invention. In some examples, the fuel tank 400 is an aircraft fuel tank.

[0068] Figure 5 An example aircraft 500 including a single-sided fastener (not visible) according to the invention is shown. The aircraft 500 has a pair of wings 502 attached to a fuselage 501. Each wing 502 includes a structural wing box formed by a front wing sparb, a rear wing sparb, an upper cover plate, and a lower cover plate. Any two or more wing box components can be integrally formed. At least some of the joints between the wing box components can include one or more single-sided fasteners according to the invention. Each wing box at least partially defines a fuel-containing space and can therefore have… Figure 4Any feature of the example fuel tank 400. Where the joint between the wing box components forms part of the wall of the fuel-containing space, any fastener included in the joint extending into the fuel-containing space can advantageously be a single-sided fastener according to the invention (such as the example single-sided fastener 10 or example single-sided fastener 30 described above). The aircraft 500 may additionally include one or more other fuel tanks. Any such other fuel tank may include a substructure fastened together by one or more single-sided fasteners according to the invention. Although the illustrated aircraft is a commercial airliner, the above discussion equally applies to any other type of aircraft or virtually any other means of transportation that includes a fuel-containing space defined by fastened substructures.

[0069] Although the invention has been described above with reference to one or more preferred examples or embodiments, it will be understood that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

[0070] Although the invention has been described above primarily in the context of applications in fixed-wing aircraft, it can also be advantageously applied to a variety of other applications, including but not limited to applications in vehicles such as helicopters, drones, trains, automobiles, and spacecraft.

[0071] Where the term "or" has been used in the above description, unless otherwise expressly stated, the term should be understood to mean "and / or".

Claims

1. A single-sided fastener configured to be installed in a hole of a given length, the single-sided fastener comprising: A deformable sleeve member having a head, a tail, and a deformable section located between the head and the tail, wherein the deformable section is configured to deform during installation of the one-sided fastener, and the sleeve member has a predetermined outer surface area configured to be disposed within the hole after installation of the one-sided fastener. A bolt member, at least partially received within the sleeve member, the bolt member having a head end portion forming a head and a tail end portion opposite to the head end portion; and An insulating component, which is fixedly arranged on the sleeve component. The insulating member and the sleeve member are configured such that the insulating member exists on a first sub-region of the predetermined outer surface region and not on a second sub-region of the predetermined outer surface region, each of the first and second sub-regions including the entire circumference of the sleeve member. The second sub-region is relatively closer to the head end of the bolt member than the first sub-region. The first sub-region includes a surface feature portion, which is shaped to match the shape of the edge of the insulating member arranged on the predetermined outer surface region. Wherein, the entire circumference of the sleeve component is continuous in the first sub-region. The insulating member includes an interlocking circumferential recess formed in the inner surface of the insulating member. The sleeve component includes an interlocking circumferential protrusion that extends radially outward from the sleeve component in the first sub-region. The circumferential protrusion is configured to be received within the circumferential recess to form a mechanical interlock between the sleeve member and the insulating member, and to resist relative axial movement between the insulating member and the sleeve member.

2. The single-sided fastener according to claim 1, wherein, The first sub-region is relatively closer to the tail end of the single-sided fastener and the second sub-region is relatively closer to the head end of the single-sided fastener.

3. The single-sided fastener according to claim 1 or claim 2, wherein, The diameter of the first sub-region is smaller than the diameter of the second sub-region by an amount substantially equal to the thickness of the insulating member.

4. The single-sided fastener according to claim 1 or claim 2, wherein, The diameter of the second sub-region is substantially equal to the outer diameter of the insulating member.

5. The single-sided fastener according to claim 1, wherein, The outer surface of the deformable section does not overlap with the predetermined outer surface area.

6. The single-sided fastener according to claim 1 or claim 2, wherein, The single-sided fastener is movable between a pre-installed configuration and a post-installed configuration, in which the sleeve member is undeformed and the tail end of the sleeve member has a first axial position relative to the bolt member; in the post-installed configuration, the sleeve member is deformed and the tail end of the sleeve member has a different second axial position relative to the bolt member.

7. The single-sided fastener according to claim 1 or claim 2, wherein, The insulating component is elastically deformable or plastically deformable.

8. The single-sided fastener according to claim 1, wherein, The surface feature portion and the edge are configured to maintain close contact between the surface feature portion and the edge during and after installation of the single-sided fastener.

9. The single-sided fastener according to claim 8, wherein, The surface feature and the edge include one or more of the following: a matching tapered portion, a matching stepped portion.

10. The single-sided fastener according to claim 1 or claim 2, wherein, The tail end of the insulating component is open.

11. The single-sided fastener according to claim 1 or claim 2, wherein, The tail end of the insulating member is closed, so that the tail ends of the bolt member and the sleeve member are enclosed within the insulating member.

12. The single-sided fastener according to claim 1 or claim 2, wherein, The top surface of the head of the sleeve component abuts against the lower surface of the head of the bolt component.

13. An assembly including a single-sided fastener, the assembly further comprising: A structural component having a hole for connecting a first side portion of the structural component to a second side portion of the structural component. The single-sided fastener is a single-sided fastener according to any one of claims 1 to 12, and the single-sided fastener is installed in the hole.

14. The assembly including a single-sided fastener according to claim 13, wherein, The end portion of the insulating member closest to the head end of the single-sided fastener is disposed within the hole.

15. The assembly including a single-sided fastener according to claim 14, wherein, The outer surface of the portion of the insulating member disposed within the hole is in close contact with the hole, and the second sub-region of the predetermined outer surface region of the sleeve member is in close contact with the hole.

16. The assembly comprising a single-sided fastener according to any one of claims 13-15, wherein, The structural component includes a first sub-structural component and a second sub-structural component fastened together by the single-sided fastener.

17. The assembly including a single-sided fastener according to claim 16, wherein, The head of the single-sided fastener abuts against the first sub-structure and the tail of the single-sided fastener abuts against the second sub-structure, wherein the axial length of the first sub-region is less than the thickness of the second sub-structure.

18. The assembly comprising a single-sided fastener according to any one of claims 13-15, wherein, The structural component includes composite materials.

19. The assembly including a single-sided fastener according to claim 18, wherein, The structural components also include metallic materials.

20. A fuel tank comprising a single-sided fastener according to any one of claims 1 to 12 and / or an assembly comprising a single-sided fastener according to any one of claims 13 to 19.

21. An aircraft comprising a single-sided fastener according to any one of claims 1 to 12, an assembly including a single-sided fastener according to any one of claims 13 to 19, or a fuel tank according to claim 20.

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