# Patent

## Title
Anti-rotation rivetless nut plate

## Abstract

A method and apparatus for fastening structures. A first end of a body is placed into a hole on a first side of the structures. The body has an outer surface with a noncircular cross-section. A nut element is positioned on a flange at a second end of the body. A bolt is moved into a channel at the first end of the body towards the nut element on the flange on the second end of the body on the first side the structures. The bolt and the nut element are fastened to each other.

## Background
BACKGROUND INFORMATION
1. Field
The present disclosure relates generally to manufacturing and, in particular, to connecting structures to each other. Still more particularly, the present disclosure relates to a method and apparatus for connecting a stack up of structures to each other using a fastener system that includes a nut plate.
2. Background
In manufacturing objects, structures are often connected to each other. For example, in manufacturing an object, such as an aircraft, many different structures are connected to each other to form assemblies for systems in the aircraft. For example, skin panels may be attached to ribs and spars. As another example, floor panels may be connected to support structures in a fuselage to form the floor of a passenger cabin.
In connecting the structures to each other, different types of connecting systems may be used. One type of connecting system is a fastener system. A fastener system may include one or more fasteners. For example, a fastener for a fastener system may be a screw. In another example, a fastener system may be a bolt and a nut.
These fasteners are used to connect structures to each other. Holes are then formed in the structure. Next, nuts and bolts are installed relative to the holes.
In some cases, access to both sides of the structure may not be feasible. For example, automated equipment may not be able to access both sides of the structure to install fasteners. As a result, a human operator or additional equipment may be used to install the fasteners. In some cases, the location of the structure may make access to the inside fastening elements impossible.
One manner in which fasteners may be installed involves using a nut plate. A nut plate may be installed relative to a hole. The nut plate is configured to prevent movement of the nut element when the bolt is rotated. The nut plate is typically held in place through adjacent holes and rivets.
To reduce part count and installation time, rivetless nut plates may be utilized. Rivetless nut plates rely on friction to resist rotation in the hole. In composite materials, obtaining sufficient interference to resist rotation while not causing inconsistencies to the composite material may be difficult.
Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.
SUMMARY
An illustrative embodiment of the present disclosure provides an apparatus comprising a body and a flange. The body has a channel extending from a first end of the body to a second end of the body. The channel has a circular cross-section configured to receive a first fastener, and the body has an outer surface that has a noncircular cross-section. The flange is associated with the second end. The flange is configured to hold a second fastener.
Another illustrative embodiment comprises a fastener system. The fastener system comprises a nut plate having a body and a flange. The body has a channel extending from a first end of the body to a second end of the body. The channel has a circular cross-section and, the body has an outer surface having a noncircular cross-section. The flange is associated with the second end of the body.
Yet another illustrative embodiment provides a method for fastening structures. A first end of a body is placed into a hole on a first side of the structures. The body has an outer surface with a noncircular cross-section. A nut element is positioned on a flange at a second end of the body. A bolt is moved into a channel at the first end of the body towards the nut element on the flange on the second end of the body on the first side of the structures. The bolt and the nut element are fastened to each other.
The features and functions can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments in which further details can be seen with reference to the following description and drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
The novel features believed characteristic of the illustrative embodiments are set forth in the appended claims. The illustrative embodiments, however, as well as a preferred mode of use, further objectives and features thereof, will best be understood by reference to the following detailed description of an illustrative embodiment of the present disclosure when read in conjunction with the accompanying drawings, wherein:
FIG. 1 is an illustration of a manufacturing environment in accordance with an illustrative embodiment;
FIG. 2 is an illustration of a fastener system in accordance with an illustrative embodiment;
FIG. 3 is an illustration of a section of structures with a fastener system in accordance with an illustrative embodiment;
FIG. 4 is another illustration of a section of structures with a fastener system in accordance with an illustrative embodiment;
FIG. 5 is an exploded view of a section of structures with a fastener system in accordance with an illustrative embodiment;
FIG. 6 is an illustration of a top view of a section of structures with a fastener system in accordance with an illustrative embodiment;
FIG. 7 is an illustration of a cross-sectional view of structures and a nut plate in accordance with an illustrative embodiment;
FIG. 8 is another illustration of a cross-sectional view of structures and a nut plate in accordance with an illustrative embodiment;
FIG. 9 is an illustration of an outer side of a structure with a body of a nut plate in accordance with an illustrative embodiment;
FIG. 10 is an illustration of a fastener system in accordance with an illustrative embodiment;
FIG. 11 is an illustration of a hole in accordance with an illustrative embodiment;
FIG. 12 is an illustration of a flowchart of a process for fastening structures in accordance with an illustrative embodiment;
FIG. 13 is an illustration of a block diagram of an aircraft manufacturing and service method in accordance with an illustrative embodiment;
FIG. 14 is an illustration of a block diagram of an aircraft in which an illustrative embodiment may be implemented;
FIG. 15 is an illustration of various shapes for a noncircular cross-section of the outer surface of a body of the fastener system depicted in accordance with an illustrative example; and
FIG. 16 is an illustration of various platforms in which a stack up of structures can be implemented in accordance with an illustrative example.



DETAILED DESCRIPTION
The illustrative embodiments recognize and take into account one or more different considerations. For example, the illustrative embodiments recognize and take into account that structures may be connected to each other using nut plates. The illustrative embodiments, however, recognize and take into account that with composite structures, the use of nut plates may be more difficult than desired.
One solution may involve using nut plates that are held in place using rivets. The nut plate may have holes to receive rivets that may be placed into structures.
Use of rivets, however, may be undesirable. For example, the use of rivets requires additional holes to be formed in a composite structure. The formation of additional holes increases the chances that an inconsistency may occur. Additionally, the formation of additional holes requires more time and equipment. Further, the use of rivets may also increase the weight of the structure more than desired. Also, the nut plates that use rivets may not provide a desired spacing between fasteners.
The illustrative embodiments also recognize and take account that a gang channel may be used in place of rivets. A gang channel is a device that connects multiple nut elements together. The use of gang channels may also be impractical if a limited number of nut elements are being applied, or if the pattern of nut elements applied is irregular to the form of the gang channel. The use of gang channels also requires time to apply and adds additional costs, making them inefficient to use in some situations.
Thus, the illustrative embodiments provide a method and apparatus for fastening structures. In one illustrative example, an apparatus comprises a body and a flange. The body has a channel extending from a first end of the body to a second end of the body. The channel has a circular cross-section configured to receive a first fastener, and the body has an outer surface that has a noncircular cross-section. The flange is associated with the second end. The flange is configured to hold a second fastener. In these illustrative examples, the first fastener may be a bolt and the second fastener may be a nut element.
With reference now to the figures and, in particular, with reference to FIG. 1, an illustration of a manufacturing environment is depicted in accordance with an illustrative embodiment. As depicted, manufacturing environment 100 is an environment in which an assembly of structures 102 for wing 104 is performed.
In this illustrative example, operator 106 and operator 108 connect structures 102 to each other within wing 104. As depicted, structures 102 include leading edge rib 110 and leading edge skin panel 112.
Leading edge skin panel 112 may be connected to leading edge rib 110 through the use of fastener systems 114 installed by operator 106 and operator 108. As depicted, operator 106 is a human operator. Operator 108 is a robotic arm.
In this illustrative example, structures 102 have first side 116 and second side 118. Access to second side 118 may be more difficult or unavailable in this illustrative example. As a result, nut plates may be used to reduce or avoid the need for access to second side 118 when installing fasteners to connect leading edge skin panel 112 to leading edge rib 110.
In these illustrative examples, at least one of leading edge rib 110 or leading edge skin panel 112 may be comprised of composite materials. As used herein, the phrase “at least one of”, when used with a list of items, means different combinations of one or more of the listed items may be used and only one of each item in the list may be needed. For example, “at least one of item A, item B, or item C” may include, without limitation, item A, item A and item B, or item B. This example also may include item A, item B, and item C or item B and item C. In other examples, “at least one of” may be, for example, without limitation, two of item A, one of item B, and ten of item C; four of item B and seven of item C; and other suitable combinations. The item may be a particular object, thing, or a category. In other words, at least one of means any combination of items and number of items may be used from the list, but not all of the items in the list are required.
In the illustrative examples, a composite material is formed from two more constituents with different physical or chemical properties. For example, a matrix of resin may be mixed with the reinforcement of fibers to form a composite material. The resin may be, for example, a polyester resin, a vinyl ester resin, an epoxy resin, a shape memory polymer, and other suitable types of resins. The fibers may be, for example, carbon fibers, glass fibers, polymer fibers, and other suitable types of fibers. These components may be cured to form a rigid material. The structure formed from this and other types of composite materials may be referred to as a composite structure.
As depicted, fastener systems 114 may be implemented in accordance with an illustrative embodiment such that access to second side 118 may be reduced or inaccessible. Further, fastener systems 114, when implemented in accordance with an illustrative embodiment, may be installed more easily than with currently used fastener systems. Additionally, fastener systems 114, when implemented in accordance with an illustrative embodiment, may reduce the occurrence of inconsistencies when at least one of leading edge rib 110 or leading edge skin panel 112 are composite structures comprised of composite materials. A more detailed illustration of section 120 with fastener system 122 in fastener systems 114 is shown in FIG. 3.
The illustration of wing 104 in manufacturing environment 100 is not meant to limit the manner in which different illustrative embodiments may be implemented. For example, fastener systems 114 may be implemented in other types of structures 102 for other types of platforms.
For example, structures 102 may be for a monument, a landing gear assembly, an engine, a wing, a wall, furniture, and other suitable structures. In these illustrative examples, structures 102 may be a platform selected from one of a mobile platform, a stationary platform, a land-based structure, an aquatic-based structure, a space-based structure, a surface ship, a tank, a personnel carrier, a train, a spacecraft, a space station, a satellite, a submarine, an automobile, a power plant, a bridge, a dam, a house, a manufacturing facility, a building, and other suitable types of platforms.
With reference now to FIG. 2, an illustration of a fastener system is depicted in accordance with an illustrative embodiment. Fastener system 200 is an example of a fastener that may be used in fastener systems 114 to connect structures to each other, such as leading edge skin panel 112 to leading edge rib 110 in FIG. 1.
In this illustrative example, fastener system 200 comprises first fastener 202 and second fastener 204. First fastener 202 and second fastener 204 may be used to connect structures 206 to each other. In these illustrative examples, first fastener 202 may be bolt 208 and second fastener 204 may be nut element 210. Bolt 208 and nut element 210 are configured to engage each other. This engagement may occur when a torque is applied to at least one of bolt 208 and nut element 210.
As depicted, structures 206 are two or more structures. The structures may include at least one composite structure in the illustrative examples. As depicted, hole 212 extends through structures 206.
As depicted, fastener system 200 also may include body 214 and flange 216. These two components may take the form of nut plate 218 in these illustrative examples.
Body 214 has first end 220 and second end 222. Body 214 has channel 224 extending from first end 220 to second end 222 of body 214. Additionally, channel 224 has circular cross-section 226. Circular cross-section 226 is substantially circular in these illustrative examples. In particular, circular cross-section 226 is configured to receive first fastener 202. Thus, some deviations may be present from a perfect circle for circular cross-section 226. These deviations may be specified by tolerance based on first fastener 202. In other words, the tolerance may specify that a deviation from a perfect circle may be such that channel 224 is able to receive first fastener 202 in the form of bolt 208 such that bolt 208 may engage second fastener 204 in the form of nut element 210 in this illustrative example.
As depicted, body 214 has outer surface 228 with noncircular cross-section 230. In other words, the cross-section of outer surface 228 has a different shape from the cross-section of channel 224 extending through body 214 in these illustrative examples. Noncircular cross-section 230 is a substantially noncircular cross-section in these illustrative examples. In the illustrative example, noncircular cross-section 230 may take various forms. For example, noncircular cross-section 230 may be a cross-section having shape 231 selected from one of an ellipse, an egg shape, an oval, a tri-oval, a trefoil, a curvilinear triangle, a teardrop, a quatrefoil, a rounded corner parallelogram, a pentagon, a hexagon, a heptagon, an octagon, a nonagon, a decagon, or some other suitable shape.
Flange 216 is configured to hold second fastener 204, such as nut element 210. As depicted, flange 216 is associated with body 214 at second end 222 of body 214. When one component is “associated” with another component, the association is a physical association in the depicted examples. For example, a first component, flange 216, may be considered to be associated with a second component, body 214, by being secured to the second component, bonded to the second component, mounted to the second component, welded to the second component, fastened to the second component, and/or connected to the second component in some other suitable manner. The first component also may be connected to the second component using a third component. The first component may also be considered to be associated with the second component by being formed as part of and/or an extension of the second component.
In the different illustrative examples, flange 216 may be, for example, formed as part of second end 222 of body 214. In other illustrative examples, flange 216 may be a separate structure from body 214 and may be configured to be connected to second end 222 of body 214. Further, flange 216 may be removably connected to second end 222 of body 214 in some illustrative examples.
In these illustrative examples, structures 206 are arranged in a stack up. Hole 212 extends from first side 232 of structures 206 to second side 234 of structures 206.
First end 220 of body 214 may be placed into hole 212 on first side 232 of structures 206. The placement of body 214 with flange 216 associated with body 214 results in flange 216 being located on first side 232 of structures 206. In this illustrative example, hole 212 also has noncircular cross-section 238. Noncircular cross-section 238 is substantially the same shape as noncircular cross-section 230. Noncircular cross-section 230 may be slightly smaller. Noncircular cross-section 230 of outer surface 228 is selected such that an interference fit may still result between body 214 and hole 212 through additional processes, such as cold working.
Noncircular cross-section 230 of body 214 corresponding to noncircular cross-section 238 of hole 212 may reduce movement, such as rotation, of nut plate 218 within hole 212. This reduction in movement may occur when a force, such as a torque, is applied to at least one of bolt 208 or nut element 210.
With this type of cross-section, the interference fit may not need to be as tight as in other situations. As a result, the generation of inconsistencies in hole 212, structures 206, or both from installing nut plate 218 in hole 212 may be reduced. Further, the particular shape of noncircular cross-section 230 may be selected such that the creation of inconsistencies in hole 212, structures 206, or both from tightening at least one of bolt 208 or nut element 210 to connect structures 206 to each other may be reduced.
As depicted, body 214 may be comprised of a first material selected from at least one of a metal, a plastic, steel, aluminum, titanium, copper, polycarbonate, a composite material, or some other suitable material. Flange 216 is comprised of a second material selected from one of a metal, a plastic, steel, aluminum, titanium, copper, polycarbonate, a composite material, or some other suitable material. Body 214 and flange 216 may be comprised of the same material or different material in these illustrative examples.
Nut element 210 may be placed on flange 216. In these illustrative examples, flange 216 may have securing configuration 240. Securing configuration 240 is a shape of flange 216 that allows flange 216 to hold nut element 210 for various orientations of structures 206. For example, first side 232 may be substantially vertical, substantially horizontal to the floor, or some other orientation. With these different orientations, flange 216 may hold nut element 210 in place for engagement with bolt 208.
As depicted, bolt 208 may be moved into hole 212 from second side 234 to structures 206. This movement of bolt 208 results in bolt 208 moving into channel 224 from first end 220 of body 214. The movement of bolt 208 may be such that bolt 208 may be engaged with nut element 210 held by flange 216. This positioning may be such that nut element 210 and bolt 208 may be engaged with each other through the use of force to rotate bolt 208 in a manner that secures bolt 208 to nut element 210. As a result, structures 206 are connected to each other.
The illustration of fastener system 200 in FIG. 2 is not meant to imply physical or architectural limitations to the manner in which an illustrative embodiment may be implemented. Other components in addition to or in place of the ones illustrated may be used. Some components may be unnecessary. Also, the blocks are presented to illustrate some functional components. One or more of these blocks may be combined, divided, or combined and divided into different blocks when implemented in an illustrative embodiment.
For example, in other illustrative examples, flange 216 may be configured to hold bolt 208 in place. In this example, nut element 210 may be turned to engage bolt 208 in a manner that secures structures 206 to each other.
With reference now to FIG. 3, an illustration of a section of structures with a fastener system is depicted in accordance with an illustrative embodiment. In this illustrative example, a more detailed illustration of section 120 of structures 102 with fastener system 122 is depicted in accordance with an illustrative embodiment. In this illustrative example, an isometric view of section 120 is shown.
As seen in this illustrative example, fastener system 122 includes a number of components. As depicted, fastener system 122 includes bolt 300, nut element 302, nut plate 303, and retention device 305.
Bolt 300 is an example of a physical implementation for bolt 208 shown in block form in FIG. 2. Nut element 302 is an example of a physical implementation for nut element 210 shown in block form in FIG. 2.
Flange 304 is a component of nut plate 303 in this example. As depicted, flange 304 is an example of one physical implementation for flange 216 shown in block form in FIG. 2. Flange 304 has a configuration that is configured to maintain a position of nut element 302 when force is applied to bolt 300 in the direction of arrow 306. Additionally, retention device 305 may resist movement in the direction of arrow 307. Additionally, a body is another component of nut plate 303 but not seen in this view.
In this illustrative example, flange 304 has wall 310 and wall 312 that defines channel 314.
Nut element 302 may be placed into and held within channel 314. Retention device 305 is configured to hold nut element 302 within channel 314. In this illustrative example, retention device 305 takes the form of a retention clip and may be placed into groove 311 and groove 313 in flange 304.
As depicted, wall 310 and wall 312 of flange 304 is configured to reduce or prevent rotation of nut element 302 when bolt 300 is rotated to engage nut element 302 and connect structures 102 to each other.
With reference next to FIG. 4, another illustration of a section of structures with a fastener system is depicted in accordance with an illustrative embodiment. In this view, another isometric view of section 120 is shown. Bolt 300 can be seen in this view. Bolt 300 extends from first side 116 to second side 118 to engage nut element 302.
With reference now to FIG. 5, an exploded view of a section of structures with a fastener system is depicted in accordance with an illustrative embodiment. In this exploded view of section 120, body 500 is seen.
In this illustrative example, body 500 has first end 502 that may extend into noncircular hole 504 on second side 118 of structures 102 when body 500 is placed into noncircular hole 504. In particular, first end 502 may extend into the portion of noncircular hole 504 in leading edge rib 110. In this illustrative example, first end 502 has a noncircular shape. As depicted, flange 304 is connected to second end 506 of body 500. Hole 508 in leading edge skin panel 112 is circular. Hole 508 does not need to be noncircular because body 500 is not inserted into hole 508 in this example. Instead, hole 508 may receive bolt 300.
With reference next to FIG. 6, an illustration of a top view of a section of structures with a fastener system is depicted in accordance with an illustrative embodiment. In this example, the top view is a view of second side 118 of structures 102. In this depicted view, nut plate 303 is shown without bolt 300 and nut element 302.
Turning now to FIG. 7, an illustration of a cross-sectional view of structures and a nut plate is depicted in accordance with an illustrative embodiment. The cross-sectional view of structures 102 with nut plate 303 is shown taken along lines 7-7 in FIG. 6.
Next in FIG. 8, another illustration of a cross-sectional view of structures and a nut plate is depicted in accordance with an illustrative embodiment. The cross-sectional view of structures 102 with nut plate 303 are shown taken along lines 8-8 in FIG. 6. A view of inner side 800 is shown and described with reference to FIG. 9 below.
In FIG. 9, an illustration of an outer side of a structure with a body of a nut plate is depicted in accordance with an illustrative embodiment. In this view of outer side 800 of leading edge rib 110, first end 502 of body 500 also is seen within noncircular hole 504. In this illustrative example, channel 314 has a circular cross-section. As depicted, channel 314 is configured to receive bolt 300.
As depicted, body 500 has exterior wall 900. Exterior wall 900 has a noncircular cross-section in this illustrative example. For example, dimension 902 may be about 0.300 inches, while dimension 904 may be about 0.305 inches in this illustrative example. The noncircular cross-section of exterior wall 900 corresponds to the shape of noncircular hole 504. In other words, noncircular hole 504 also has a noncircular cross-section.
With reference next to FIG. 10, an illustration of a fastener system is depicted in accordance with an illustrative embodiment. In this depicted example, fastener system 1000 includes bolt 1002, nut element 1004, nut plate 1006, and retention device 1007.
In this illustrative example, nut plate 1006 includes body 1008 and flange 1010. As depicted, body 1008 and flange 1010 are separate pieces. These two pieces may be connected to each other prior to bolt 1002 and nut element 1004 engaging each other.
Turning now to FIG. 11, an illustration of a hole is depicted in accordance with an illustrative embodiment. In this illustrative embodiment, hole 1100 may be an example of one implementation for noncircular hole 504 in FIG. 5. As depicted, hole 1100 has a noncircular shape. The noncircular shape of hole 1100 corresponds to the noncircular shape of a nut plate in accordance with an illustrative embodiment. For example, the noncircular shape is an elliptical cross-section in this illustrative example.
As depicted, hole 1100 has center 1102. Similarly, cutter 1104 has center 1106. Center 1106 of cutter 1104 is offset from center 1102 of hole 1100 in this illustrative example. Path 1108 may be formed using the offset of center 1106 of cutter 1104 to center 1102 of hole 1100. In these illustrative examples, the offset varies such that path 1108 has an elliptical shape. In other examples, path 1108 may have another shape. In order to form hole 1100, center 1106 of cutter 1104 moves along path 1108. In this manner, cutter 1104 may create hole 1100. As depicted, hole 1100 may be created to correspond to and receive an outer surface with a noncircular cross-section in a body of a nut plate, such as nut plate 303.
The illustration of the fastener systems in FIGS. 3-11 are only provided as examples of some implementations that may be used in accordance with an illustrative embodiment. Other illustrative examples may have other shapes for the different components illustrated.
The different components shown in FIGS. 1 and 3-11 may be combined with components in FIG. 2, used with components in FIG. 2, or a combination of the two. Additionally, some of the components in FIGS. 1 and 3-11 may be illustrative examples of how components shown in block form in FIG. 2 can be implemented as physical structures. For example, other methods may be used for creating hole 1100. For example, laser drilling, electric discharge machining, and other processes may be implemented.
Turning next to FIG. 12, an illustration of a flowchart of a process for fastening structures is depicted in accordance with an illustrative embodiment. The process illustrated FIG. 12 may be implemented in a manufacturing environment, such as manufacturing environment 100 in FIG. 1, to connect structures to each other. In particular, the structures may be connected to each other using fastener system 200 in FIG. 2.
The process begins by forming the hole in the stack up of the structures prior to placing the first end of the body into the hole on the first side of the structures (operation 1200). In operation 1200, some holes in the stack up of structures may be circular while other holes may be noncircular. The circular holes are for structures through which the body of a nut plate is received in this illustrative example. The body has an outer surface with a noncircular cross-section. In the illustrative example, only one structure may be noncircular while the other structures in the stack up are circular. The circular holes in the structures are configured to receive a bolt in this illustrative example. The noncircular hole may be formed separately from the circular holes.
A nut element is positioned on a flange at a second end of the body (operation 1202). A process similar to cold working is used to install the nutplate into the rib with a slight interference level. The process then moves a bolt into a channel at the first end of the body towards the nut element on the flange on the second end of the body on the first side of the structures (operation 1204).
The bolt and the nut element are fastened to each other (operation 1206), with the process terminating thereafter. The bolt and the nut element are fastened to each other by applying a force, such as a torque, to the bolt while the nut element is held by the flange. As a result the structures are fastened to each other.
The flowcharts and block diagrams in the different depicted embodiments illustrate the architecture, functionality, and operation of some possible implementations of apparatuses and methods in an illustrative embodiment. In this regard, each block in the flowcharts or block diagrams may represent a module, a segment, a function, and/or a portion of an operation or step.
The illustrative embodiments of the disclosure may be described in the context of aircraft manufacturing and service method 1300 as shown in FIG. 13 and aircraft 1400 as shown in FIG. 14. Turning first to FIG. 13, an illustration of a block diagram of an aircraft manufacturing and service method is depicted in accordance with an illustrative embodiment. During pre-production, aircraft manufacturing and service method 1300 may include specification and design 1302 of aircraft 1400 in FIG. 14 and material procurement 1304.
During production, component and subassembly manufacturing 1306 and system integration 1308 of aircraft 1400 in FIG. 14 takes place. Thereafter, aircraft 1400 in FIG. 14 may go through certification and delivery 1310 in order to be placed in service 1312. While in service 1312 by a customer, aircraft 1400 in FIG. 14 is scheduled for routine maintenance and service 1314, which may include modification, reconfiguration, refurbishment, and other maintenance or service.
Each of the processes of aircraft manufacturing and service method 1300 may be performed or carried out by a system integrator, a third party, and/or an operator. In these examples, the operator may be a customer. For the purposes of this description, a system integrator may include, without limitation, any number of aircraft manufacturers and major-system subcontractors; a third party may include, without limitation, any number of vendors, subcontractors, and suppliers; and an operator may be an airline, a leasing company, a military entity, a service organization, and so on.
With reference now to FIG. 14, an illustration of a block diagram of an aircraft is depicted in which an illustrative embodiment may be implemented. In this example, aircraft 1400 is produced by aircraft manufacturing and service method 1300 in FIG. 13 and may include airframe 1402 with systems 1404 and interior 1406. Examples of systems 1404 include one or more of propulsion system 1408, electrical system 1410, hydraulic system 1412, and environmental system 1414. Any number of other systems may be included. Although an aerospace example is shown, different illustrative embodiments may be applied to other industries, such as the automotive industry.
Apparatuses and methods embodied herein may be employed during at least one of the stages of aircraft manufacturing and service method 1300 in FIG. 13. The different illustrative examples may be implemented in component and subassembly manufacturing 1306 to connect structures to each other to form assemblies. Further, the illustrative examples also may be used during system integration 1308 with assembling aircraft 1400. Illustrative embodiments also may be used during maintenance and service 1314. The illustrative embodiments may be used to connect structures to each other during maintenance, refurbishment, upgrades, and other operations. The use of a number of the different illustrative embodiments may substantially expedite the assembly of and/or reduce the cost of aircraft 1400.
With reference now to FIG. 15, an illustration of shapes for a noncircular cross-section of an outer surface of a body of a fastener system is depicted in accordance with an illustrative example. In this illustrative example, the shapes depicted in FIG. 15 having a noncircular cross-section a more detailed illustration, noncircular cross-section 230 of outer surface 228 for body 214.
As depicted, shapes for a noncircular cross-section may take various forms. For example, noncircular cross-section 230 may be a cross-section having a shape selected from one of ellipse cross-section 1502, egg cross-section 1504, oval cross-section 1506, tri-oval cross-section 1508, trefoil cross-section 1510, curvilinear triangle cross-section 1512, teardrop cross-section 1514, quatrefoil cross-section 1516, rounded corner parallelogram cross-section 1518, pentagon cross-section 1520, hexagon cross-section 1522, heptagon cross-section 1524, octagon cross-section 1526, nonagon cross-section 1528, and decagon cross-section 1530.
With reference now to FIG. 16, an illustration of platforms in which a stack up of structures utilizing a fastener system can be implemented is depicted in accordance with an illustrative example. In this illustrative example, the platforms depicted in FIG. 16 are examples of structures 102 having fastener systems 114, both shown in FIG. 1, implemented therein.
As depicted, the platforms may take various forms. For example, the platforms of FIG. 16 may be a selected from one of mobile platform 1602, stationary platform 1604, land-based structure 1606, aquatic-based structure 1608, space-based structure 1610, surface ship 1612, tank 1614, personnel carrier 1616, train 1618, spacecraft 1620, space station 1622, satellite 1624, submarine 1626, automobile 1628, power plant 1630, bridge 1632, dam 1634, house 1636, manufacturing facility 1638, and building 1640.
The illustrative embodiments provide a method for connecting structures to each other using fastener systems. In the illustrative examples, the nut plate has a body that has an exterior surface that has a noncircular cross-section. Although an ellipse, the depicted shape of the noncircular cross-section, has been shown in the illustrative examples, other shapes may be used other than an elliptical cross-section such that the shapes allow for increased resistance to rotation of the body of the nut plate within the hole when a torque is applied to tighten a bolt to a nut element installed in the hole and nut plate. In this manner, cold working may be used to create a slight interference fit to secure the nut plate to the composite structure. With the use of the nut plate, the number of holes formed in composite structures may be reduced when rivets are unnecessary. Further, weight caused by the use of other types of techniques, such as those using gang channels, may be avoided. Of course, the different illustrative embodiments may be applied to other types of structures other than composite structures. For example, the illustrative embodiments may be applied to metal, plastic, and other structures that employ other types of materials.
The different illustrative embodiments may be applied in a number of different ways. For example, the fastener system may be employed by at least one of a human operator, automated equipment, equipment controlled by human operators, or other suitable types of operators.
The description of the different illustrative embodiments has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Further, different illustrative embodiments may provide different features as compared to other illustrative embodiments. The embodiment or embodiments selected are chosen and described in order to best explain the principles of the embodiments, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.

## Claims

1. An assembly comprising:
a first structure, comprising a first-structure through opening,
the first-structure through opening having all walls parallel to a first axis and having an oval cross-section in a first plane, orthogonal to the first axis,
the first structure having first planar opposing surfaces, orthogonal o the first axis;

a second structure, comprising a second-structure through opening,
the second-structure through opening having all walls parallel to the first axis and having a circular cross-section in a second plane, orthogonal to the first axis,
the second-structure through opening being concentric with the first-structure through opening, the second structure having second planar opposing surfaces, orthogonal to the first axis;

a nut plate, comprising a first component and a second component, separate from the first component, and a retention clip;
wherein the first component comprises a first plate, an elongated body, and a first-component through opening, wherein:
the first plate comprises at least two parallel edges,
the elongated body extends from the first plate,
the elongated body is geometrically complementary with the first-structure through opening of the first structure prior to insertion of the elongated body into the first-structure through opening of the first structure,
the first component is not rotatable relative to the first structure when the elongated body is inserted into the first-structure through opening of the first structure,
the first component is translationally fixed relative to the first structure along the first axis by an interference fit between the elongated body and the first-structure through opening in the first structure, and
the first-component through opening penetrates the first plate and the elongated body of the first component;

wherein the second component comprises a second plate, at least two opposing walls, a channel, and complementary peripheral grooves, wherein:
the second plate is located between the first structure and the first plate of the first component,
the second plate comprises a second-component through opening, receiving the elongated body of the first component,
the at least two opposing wails extend from the second plate, the channel is located between the at least two opposing walls,
the opposing walls are complementary with the at least two parallel edges of the first plate of the first component,
the complementary peripheral grooves extend along an outer surface of the at east two opposing walls, and
the complementary peripheral grooves are configured to receive the retention clip; and


a nut element, comprising a nut plate and a nut body, wherein:
the nut plate comprises at least two parallel edges,
the opposing walls of the second component are complementary with the at least two parallel edges of the nut plate,
the first component, the second component, and the nut element are non-rotationally coupled when the first plate of the first component and the nut plate of the nut element are received in the channel of the second component, and
the nut body extends from the nut plate and comprises a nut threaded opening; and

a bolt, comprising a shank,
wherein, when the shank of the bolt protrudes through the second-structure through opening, the first-structure through opening, the first-component through opening, and the second-component through opening and threadably engages the nut threaded opening of the nut body, the shank of the bolt centers the second-structure through opening relative to the first-component through opening.

2. The assembly of claim 1, wherein the first structure further comprises a first composite structure, and wherein the second structure further comprises a second composite structure.

3. The assembly of claim 2, wherein the first composite structure further comprises a leading-edge skin panel of an aircraft, and wherein the second composite structure further comprises a leading-edge rib of the aircraft.

4. The assembly of claim 1, wherein the first structure and the second structure are included in a stack up of structures.

5. The assembly of claim 4, wherein the stack up of structures are for a platform selected from one of a mobile platform, a stationary platform, a land-based structure, an aquatic-based structure, a space-based structure, a surface ship, a tank, a personnel carrier, a train, a spacecraft, a space station, a satellite, a submarine, an automobile, a power plant, a bridge, a dam, a house, a manufacturing facility, and a building.

6. The assembly of claim 1, wherein a first component of the nut plate comprises a first material selected from the group consisting of a metal, a plastic, steel, aluminum, titanium, copper, polycarbonate, and a composite material, and wherein the second component of the nut plate comprises a second material selected from the group consisting of a metal, a plastic, steel, aluminum, titanium, copper, polycarbonate, and a composite material.

7. The assembly of claim 6, wherein the first material is different from the second material.

8. The assembly of claim 6, wherein the first material is same as the second material.

9. The assembly of claim 1, wherein the first-component through opening having all walls parallel to the first axis and having a circular cross-section in a third plane, orthogonal to the first axis, and parallel to the second plane.

10. The assembly of claim 9, wherein a diameter of the first-component through opening is same as a diameter of the second-structure through opening.