Method and apparatus for forming a corrugated web having a continuously varying shape

A method and apparatus are used to form a corrugated web having a cross sectional shape with at least one characteristic that varies substantially continuously along the substantially the entire length of the web. The apparatus includes multiple sets of dies which progressively form corrugations in a moving sheet. At least one characteristic of the web's cross sectional shape is varied along the entire length of the web by displacing the dies as the sheet moves through the die sets.

TECHNICAL FIELD

This disclosure generally relates to corrugated structural members, especially corrugated webs used as cores to stiffen aircraft wing panels, and deals more particularly with a method and apparatus for forming a corrugated web having a shape that continuously varies along its length.

BACKGROUND

Certain structures used in aircraft, such as, without limitation, wings, horizontal and vertical stabilizers, fins and the like may be formed from panels designed to meet or exceed specified design loads along the length of the panel. In order to tailor the design load along the length of a wing panel, structural features of the panel may be varied from the root to the tip of the wing. For example, in the case of a panel construction having a corrugated web sandwiched between two skins, it may be possible to continuously vary certain characteristics of the corrugated web, such as the thickness, amplitude, or wavelength of the web along its length to achieve the desired load tailoring.

Existing techniques for forming corrugated webs are limited to producing webs having a substantially uniform cross section over the length of the web. A problem therefore exists in forming a corrugated web having a shape that varies continuously along a length sufficient for use in a wing panel

Accordingly, there is a need for a method and apparatus for forming corrugated webs having a shape that continuously varies along the length of the web. There is also a need for a method and apparatus for producing such corrugated webs in a substantially continuous process.

SUMMARY

The disclosed embodiments provide a method and apparatus for forming a web having a corrugated cross sectional shape that varies substantially continuously along the length of the web. A continuous process is used to form one-piece plastic or metal corrugated webs of various lengths. The corrugated webs may be used as cores in sandwich-type panel constructions employed in the aircraft industry to form wings, fins, stabilizers and the like. The varying cross sectional shape of the corrugated webs may allow continuous load tailoring of wing panels from root to tip. The embodiments provide real time capability for varying the corrugated dimensions of sheet metal and thermoplastic shapes.

According to one disclosed embodiment, apparatus is provided for forming a corrugated web having a cross sectional shape with at least one characteristic that varies substantially continuously along the length of the web. The apparatus includes: a plurality of die units arranged in sets for progressively forming corrugations in a sheet of material; means for moving the sheet through the sets of die units; and, means for displacing the die units in synchronization with the movement of the sheet. The means for displacing the die units may include mechanisms for simultaneously rotating and moving the die units laterally as the sheet moves through the forming die units.

According to another disclosed embodiment, apparatus is provided for forming a web having corrugations along its length, comprising: means for moving a sheet of material along a first axis; roller dies arranged in sets along the first axis for forming corrugations in the sheets; and, means for synchronously rotating at least certain of the roller dies along a second axis extending transverse to the first axis and for displacing the roller dies along the third axis extending transverse to the first and second axes. The roller dies are spaced apart along the first axis and progressively engage the sheet as the sheet moves along the first axis.

According to a disclosed method embodiment, forming a corrugated web, comprises: moving a sheet of material through a forming station; using multiple sets of dies at the forming station to progressively form corrugations in the sheet as the sheet moves through the forming station; and, changing at least one characteristic of the cross sectional shape of the web by displacing at least certain of the dies as the sheet is moving through the forming station. Progressively forming the corrugations includes using a first set of dies to form the general shape of the corrugations, and using a second set of dies to form the final thickness of the corrugations. Progressively forming the corrugations may further include forming corrugations in a central portion of the sheet and then forming corrugations in the sheet on opposite sides of the central portion. Displacing the dies may include moving the dies laterally away from the centerline of the sheet and rotating the dies in the lateral movement.

According to a further method embodiment, forming a corrugated web comprises: moving a sheet of material along the first axis; forming a set of corrugations in the sheet as the sheet is moving along the first axis by passing the sheet through a set of dies; and varying a characteristic of the cross sectional shape of the web by displacing the dies along a second axis traverse to the first axis as the sheet moves through the set of dies.

The disclosed embodiments satisfy the need for a method and apparatus for forming a web having a cross sectional shape with at least one characteristic that varies substantially continuously along the length of the web. The disclosed embodiments also satisfy the need for aircraft skin panels employing such a web in order to allow load tailoring along the length of the panel.

Other features, benefits and advantages of the disclosed embodiments will become apparent from the following description of embodiments, when viewed in accordance with the attached drawings and appended claims

DETAILED DESCRIPTION

Referring first toFIGS. 1-6, a structure such as an aircraft wing section50has structural strength or stiffness that varies substantially along its length “L”, so as to closely match design loads for the wing. The length L may comprise the entire length of a wing (not shown) or only a portion of the wing length. For example, the structural strength of a wing section50may vary continuously from root to tip, interrupted only by load features of the wing such as engine struts.

The wing section50may include leading edge structure52and trailing edge structure54formed in a conventional manner. The leading edge and trailing edge structures52,54are connected by upper and lower wing skins58,60respectively comprising a plurality of elongate skin panels62joined together along their edges. The upper and lower skins58,60form a region of use64in which the skins58,60provide structural strength or stiffness that varies substantially continuously along the length of the wing section50and is closely matched to the design load requirements of the wing section50. The wing section50may include internal structure (not shown) for providing additional chord-wise or span-wise stiffness, as may be required for the particular application. As will be discussed below in more detail, the wing skins58,60may be formed from any of various materials, including metals, composites and combinations thereof.

As shown inFIG. 3, each of the panels62comprises a stiffener web66sandwiched between and joined to outer and inner facesheets68,70. The web66includes a fluted or corrugated-like, repeating pattern across the width of the panel62, viewed from an end of the wing section50, as shown inFIG. 2. For convenience of description, the web66may be referred to herein as a “corrugated web” or a web66having “corrugations” defined by a repeating pattern of grooves61and ridges63. It is to be understood, however, that the repeating pattern of ridges61and grooves63need not be parallel to each other but rather, may tapered or angled with respect to each other along either the entire length of the web66, or only a portion of the length of the web66. Moreover, the repeating pattern of the web66may have one or more characteristics or dimensions that may vary across the width or cross section of the web66, and these varying characteristics or dimensions may also vary along the entire length of the web66or along only a portion of the length of the web66.

In the embodiment illustrated inFIGS. 1-6, the cross sectional shape of the corrugated web66is an undulating sine wave, however as will be discussed below, a variety of other cross sectional shapes are possible. The repeating pattern of the web66has a wavelength λ and amplitude “a” which may be substantially equal to the spacing between facesheets68,70. The web66may be joined to the facesheets68,70at alternating upper and lower contact points65using any of various techniques discussed below.

FIG. 4illustrates a typical joint between adjacent panels62in which adjacent edges67of facesheets68,70are connected by welds72. Depending on the materials from which the facesheets68,70are fabricated, it may also be possible to bond the facesheets at the adjacent edges67.

FIG. 5illustrates an alternate joint between adjacent panels62in which a web or wall74running substantially the entire length of the panel62is joined to each of the facesheets68,70by welding or bonding. The wall74, which extends traverse to the facesheets68,70may comprise a discrete member, or may comprise a tab that is formed by bending an edge of either one of the facesheets68,70on one of the panels62. The wall74may be joined to each of the webs66, if desired in order to increase the stiffness of the resulting joint.

FIG. 6illustrates how a front spar76of the leading edge structure52may be integrated into the upper wing skin58. A tab69forming part of the front spar76is angled so as to extend generally parallel to the contour of the skin58and may be joined to the lower facesheet70.

As previously noted, the web66may possess any of a variety of repeating patterns across the width of each panel62, and includes at least one dimension or geometric feature that varies substantially continuously along the length L of the panel62(FIG. 1) in order to provide substantially continuous varying stiffness that closely matches the profile of design load along the length L of wing section50. Thus, as used herein, “repeating pattern” means a pattern which is generally repeating but with variations in one of more characteristics or dimensions of the pattern.FIGS. 7aand7billustrate a web66ahaving a hat-shaped repeating pattern with a constant wavelength λ, whileFIGS. 8aand8billustrate a web66billustrating a sine wave pattern.FIGS. 9aand9billustrate a web66chaving a square wave pattern whileFIGS. 10aand10billustrate a web66dhaving a sawtooth wave pattern. Finally,FIGS. 11aand11billustrate a web66ehaving a repeating T-shape wave. While the wavelengths of the webs66a-66edescribed above are constant, it is also possible to employ a wavelength λ that varies along the length L of the wing section50, as will be described below.

FIG. 12illustrates an airplane82having wings78and horizontal stabilizers84employing a wing skin58exhibiting substantially continuous varying stiffness along its length. The wing78comprises leading and trailing edge structures52,54and a wing tip structure75, all joined to a series of wing skin panels62having substantially uniform width from the root86to the tip88of the wing78. Thus, wing78possesses a substantially non-tapered wing skin58. In contrast, as shown inFIG. 13, an airplane82includes wings90and horizontal stabilizers92that have a tapered wing skin58a, resulting from the use of wedge shaped wing skin panels62athat taper from the root86to the outer tip88of the wing90.

Reference is now made toFIG. 14which illustrates an alternate embodiment of the wing skin58bformed of panels62bhaving substantially uniform width, and a depth or thickness “t” that varies substantially continuously from the wing root86toward the wing tip88. The cross section of the wing skin58badjacent the wing root86is indicated by the numeral94, while the cross section at the wing tip88is designated by the numeral96. As is evident from the cross sections94,96, the amplitude of the web66, which in the illustrated example is a sine wave, decreases substantially continuously along the length of the wing skin58b, from the root86to the tip88.

FIG. 15illustrates a wing skin58cin which substantially continuous varying structural strength along the length of the wing skin58cis achieved by varying the wavelength λ of the sine wave pattern of the web66substantially continuously, from the wing root86toward the wing tip88. In the illustrated example, greater structural strength at the wing root86is achieved by using a shorter wavelength web66while the web66near the wing tip88has a longer wavelength. This variation in wavelength λ of the web66from the root86to the tip88results in wing skin panels62cthat are generally tapered, with the peaks of the web66being closer together at the wing root86than at the wing tip88.

FIG. 16illustrates a wing skin58dthat employs the techniques of the wing skins58b,58crespectively shown inFIGS. 14 and 15. Each of the wing skin panels62dof the wing skin58demploy a web60that varies substantially continuously both in the wavelength λ and amplitude “a” (seeFIG. 3) of the sine wave pattern from root86to tip88. More specifically, the wavelength λ increases from root86to tip88, while the amplitude “a” decreases from root86to tip88. Other geometric features or dimensions of the web60may be substantially continuously varied substantially continuously along the length of the wing skin58in order to provide a structural strength profile that closely matches the designed load profile of the wing. For example, the thickness of the material from which the web60is formed may be varied substantially continuously along the length of the wing skin58. Also, the thickness of the facesheets6870, may be varied substantially continuously along the length of the wing skin58, from root86to tip88.

The wing skin panels62described above may be fabricated using apparatus and a process generally indicated by the numeral98inFIGS. 17 and 18. Referring now toFIGS. 17-19, sheet material100, which may comprise, for example and without limitation, metal, is drawn from a supply roll102and is passed through a web forming station104which may include roller dies106or similar tooling that squeezes and deforms the sheet material100so as to impart a repeating pattern to the sheet material100. The repeating pattern matches the geometry of the roller dies106which can be varied so as to vary characteristics of the pattern, such as the wavelength λ and the amplitude “a”. The dimensions of the resulting web66are controlled by the web forming roller dies106which produce the variations in a substantially continuous, preprogrammed way, resulting in a load tailored core in a single step. Additional details of one suitable web forming station104are described in U.S. Pat. No. 6,834,525 issued Dec. 28, 2004. Details of another suitable web forming station104will be discussed below. The width and thickness of the sheet material100may be determined before processing is commenced, depending upon the requirements of the application. In some applications, the sheet material100may be preformed with varying thickness and/or width before being placed on the supply roll102. For example, the metal sheet material100may be rolled or machined before it is passed through the forming station104. In the case of skins formed composite materials, the web66may be simply molded to facesheets having a varying thickness.

The formed web108moves from the forming station104in the direction of the arrows105to a collimator114shown inFIGS. 17,18and20. As the continuous web108is fed to the collimator114, facesheet material110drawn from supply rolls109is guided by rollers112onto the upper and lower surfaces of the continuous web108. As shown inFIGS. 17,18and20, the collimator114may comprise, for example and without limitation, a pair of pinch rollers117with included edge guides (not shown) which function to draw the two continuous lengths of facesheet material110and the formed web108into a sandwich115that emerges from the collimator114and is then drawn into a shaping station116shown inFIGS. 17,18and21. The rollers and edge guides117ensure lateral alignment and keep the constant level of tension on the sheet material100. The collimator114ensures that the facesheet material110and the web108are lined up with each other laterally.

The shaping station116may include shaping apparatus120comprising, for example and without limitation, two sets of camber and guide rollers122which are arranged to deform the continuous sandwich115into the desired cross sectional shape matching the desired surface profile of the wing. The cross sectional shape of the sandwich115, and thus the surface contour of the resulting wing skin is determined by the position of the sets of the camber and guide rollers122which may be varied using servo-motor controlled rods124or other means for altering the configuration of the sets of rollers122.

A digital controller (not shown) may be programmed to control the servo-control rods124and thus the position of the rollers122. As the panel sandwich122moves through the shaping station116, the contour imparted to the sandwich122may change, corresponding to the change in airfoil shape along the span of the wing, except in those applications employing constant chord wing designs. Shaping of the wing skin panels62to match local wing surface contours may eliminate or reduce the need for ribs and/or other support structure to maintain the shape of the wing. Moreover, fewer ribs may be required to support skin panels62.

After passing through the shaping station116, the shaped sandwich118is passed through a brazing facility126, as shown inFIGS. 17,18and22. The brazing facility126joins the web66to the facesheets68,70by brazing, in the case of a metallic wing. Where the components of the skin panels are formed from composite material however, the components would be passed through a bonding facility (not shown), rather than the brazing facility126. As shown inFIGS. 17 and 18, a second set of camber and guide rollers128may be employed to hold the shaped sandwich118while the brazed panel62is cooling. The finished wing skin panel62exits the apparatus98at131and may be cut to the desired shape or length using any suitable apparatus (not shown). From the foregoing, it may be appreciated that substantially continuous, near optimal variation in the amount of structural material may be used to complete the wing skins58in essentially a single manufacturing operation.

Attention is now directed toFIG. 23which illustrates, in simplified form, a process for fabricating wing skins having substantially continuously varying structural strength along their lengths. Beginning at130, the web66is formed at a web forming station104(FIG. 17) or using other similar processes. Next, at132, the web66is sandwiched between opposing facesheets68,70. The sandwich is then formed into the shape of the panel at134in order to achieve the desired surface contour of the skin. Then, at136, the web66is joined to the facesheets6870. Optionally, tabs forming the wall shown inFIG. 5may be formed on at least some of the panels as shown in step138, following which the panels are joined together at step140. The panels may be joined together using any of various known processes, such as, for example and without limitation, laser welding or friction stir welding.

As previously mentioned, the wing skin panels may be fabricated using composite materials. Where composite materials are used, a device (not shown) for forming the web66may incorporate, for example, the ability to partially cure composite core material immediately after it has been formed to the desired pitch amplitude and shape, using for example and without limitation, microwave curing. It may also be necessary or desirable to provide increased support for the shaped web during the cure stage to ensure the shape is maintained until the web is able to support itself without deformation. A suitable device (not shown) may be used to join the web to the facesheets, regardless of whether the facesheets are formed of metallic or composite materials. Such a device and related process may utilize a high strength paste adhesive and a spot or cure-on-demand curing process. Other techniques may be employed to join the web to the facesheets, depending on the materials from which they are formed, such as, without limitation, the use of selective blind fasteners and/or blind stitching. In the case of composite wing skin panels62, the edges of the panels may be joined with adhesives using a cure-on-demand process.

Attention is now directed toFIG. 24which illustrates the details of one embodiment of the web forming station104previously discussed in connection withFIGS. 18 and 19. For convenience of description, details of the web forming station104shown inFIG. 24will be discussed in connection with the corrugated web108ashown inFIG. 27which has a hat-shaped cross section that includes alternating flat tops108b,108cconnected by diagonal legs108d. The arrangement of the alternating tops108b,108cand diagonal legs108deffectively define alternating grooves61and ridges63which, as previously mentioned, may be collectively described as corrugations111. The web forming station104may be employed to form a corrugated web108having any of a variety of other cross sectional shapes, including, but not limited to those illustrated inFIGS. 7a-11b. Also, the web forming station104may be employed to form corrugated webs108of any of a variety of metallic materials such as, without limitation, aluminum, titanium or steel, and thermoplastic materials, with or without reinforcement.

As shown inFIG. 24, the web forming station104broadly includes a plurality of die sets142-150spaced apart along, and symmetrically arranged with respect to, a centerline107, which may comprise the centerline of the sheet100. Each of the die sets142-150includes one or more die units106which are arranged along axes109that are substantially perpendicular to the central axis107. As will be discussed below, certain features of the die units106determine the shape of the corrugations111. Webs108having differing shapes of corrugations111may be formed by changing the die units106in each die set142-150.

Each of the die sets142-150may include at least one die unit106athat is substantially aligned with the centerline107. The die sets142-150include progressively greater numbers of die units106from left to right as viewed inFIG. 24, in the direction of movement105of the sheet100. The number of die sets142-150required for forming a particular web108will be equal to n−2, where n equals the number of shapes formed in the web108. The forming changes in the web108produced by the die sets142-150are given by the formula:
FC=S1+δt1−2S2+δt2-t3S3+ . . . δt(n-3)-(n-2)Sn-2

The full width of the sheet100is fed through the multiple die sets142-150, such that the corrugations111are formed progressively, with each of the die sets142-150forming a portion of the total number of the corrugations111. Formation of the corrugations111begins in the middle of the sheet100, following which successive ones of the die sets144-150form corrugations111on opposite sides of the corrugations111previously formed in the middle of the sheet100.

The corrugated web108formed by the forming station104may be of indefinite length and possesses a cross sectional shape having at least one characteristic that varies substantially continuously along the length of the web108. In those applications where the web108is formed from a relatively heavy metallic material that may cause “spring-back” of the corrugation111if formed at room temperature, it may be necessary to heat the sheet100either before or while the sheet100is being formed. For example, induction heating stations (not shown) may be placed between the die sets142-150to facilitate hot sizing of the web108.

At least certain of the die units106in each of the die sets142-150is laterally moveable, parallel to the axis109, as indicated by the arrows162. Additionally, at least certain of the die units106may also be partially rotatable along vertical axes152, as shown at154. As will be discussed later in more detail, as the sheet100moves through the web forming station104, the die sets142-150progressively form corrugations111(FIG. 27) in the sheet100, and these corrugations111may taper relative to the central axis107as a result of the simultaneous lateral movement and rotation of certain of the die units106.

FIG. 25broadly illustrates the steps of a method for forming a corrugated web108ausing the forming station104shown inFIG. 24. Beginning at141, the sheet100is fed to the die sets142-150. As the sheet moves through the die sets142-150, one or more center corrugations111are formed by one or more die units106a, as shown at step143. At step145, outer corrugations111, on opposite sides of the center corrugations111, are progressively formed as the sheet100moves through successive ones of the die sets142-150. In an embodiment in which some of the corrugations111may be tapered, some of the die units106may be simultaneously laterally displaced and rotated, in synchronization with the movement of the sheet100. Preliminary shaping of the corrugations111is completed at149following which the shape of the corrugations111may be refined or “cleaned up” at151. Finally, at step153, the web108is formed to a final thickness.

FIG. 26illustrates additional details of one of the die sets146in which the operation of the die units106is controlled by a controller155that may comprise for example and without limitation, a PC (personal computer) or a programmable logic controller (PLC). Each of the die units106engages opposite sides of the sheet100to form a corrugation111(FIG. 27) in the sheet100as the sheet100moves through the die station146. Each of the die units106is connected to a first mechanism156which may comprise, for example and without limitation, a rotary actuator, that rotates the die unit106about axis152which extends substantially normal to the plane of the sheet100, and perpendicular to the direction of travel105(FIG. 24) of the sheet100. The first mechanisms156are mounted on second mechanisms158supported on a base160for lateral movement along the axis109shown inFIG. 24. The mechanism158may comprise a slide arrangement or gear drive which smoothly moves and controls the spacing between the die units106. Mechanisms156and158may be operated by the controller155which controls and synchronizes the rotation and lateral displacement of the die units106to produce a web108with a particular cross section shape. Additional functions of the die units106, such as the amount of pressure applied to the sheet100, may also be controlled by the controller155.

Attention is now directed toFIGS. 28 and 29which depict further details of one of the die units106used in the die sets142-146. The die unit106comprises a pair of driven pinch rollers168for engaging and moving the sheet100through a pair of matched roller dies170,172. One of the pinch rollers168and roller die172are mounted as a unit on an upper mechanism156, previously described. Similarly, the second pinch roller168and roller die170are mounted as a unit on a lower mechanism156. A slotted guide174may be provided for guiding the sheet100into the nip169of the pinch rollers168. The upper roller die172includes outer cylindrical portions172athat engage the flat tops108cof the sheet100, and a center portion172bhaving outer forming surfaces172cwhich function to form the top108band diagonal legs108dof the corrugation111.

The roller die170includes outer cylindrical surfaces170afor engaging the tops108cof the corrugation111, and a center portion170b. The center portion170bis configured to include contiguous surfaces170cwhich, in combination with surfaces172con the upper roller die172, form the tops108band the diagonal legs108dof the corrugation111.

Reference is now made toFIGS. 30-32which depict further details of the die sets148,150. As previously noted, die set148may function primarily to clean up and finalize the cross sectional shape of the web108, while die set150may function to form the final thickness of the web108. In other embodiments however, finalizing both the shape and the thickness of the web108may be jointly performed by the die sets148,150.

Each of the die sets148,150include a first set of roller dies164,166and a second set of roller dies170,172, similar to those previously described in connection withFIGS. 28 and 29. Further, a pair of pinch rollers168are disposed between the two sets of roller dies164,166and170,172which pull the partially formed web108athrough the die sets148,150.

As shown inFIG. 31, the partially formed web108apasses through a guide174into the nip179between the roller dies164,166. Roller dies164,166function to refine the shape of the partially formed web108a. Roller dies164engage the lower face of the top108cwhile roller dies166engage the upper face of the top108c. The roller dies166may each include an angled portion166aon the inner face thereof which functions to complete and/or clean up the transition between the diagonal leg108dand the top108c, as best seen inFIG. 32. In some applications, it may be desirable that the inboard portion166aof the roller die166apply pressure to the web108a, while the outboard portion166bof the roller die166apply little or no pressure to the web108aso that the material of the web108ais allowed to deform or “squeeze” outwardly beneath the outboard portion166bof the roller die166.

Following the shaping operation on the partially formed web108aperformed by roller dies164,166, the web108apasses through pinch rollers168which in turn feed the web108abetween a second pair of roller dies170,172that may be similar in construction to those previously described in connection withFIGS. 28 and 29. As the web108apasses between roller dies170,172, the pressure applied to the web108aby the roller dies170,172may be controlled to squeeze roller dies170,172more tightly, and thereby determine the final thickness to which the web108ais formed. Also, as previously described, in those applications where the thickness of the web108ais to be tailored (continuously varied) along its length, the pressure applied by roller dies170,172(and resulting material deformation) may be continuously varied in order to continuously change the thickness of the web108aalong its length.

Embodiments of the disclosure may find use in a variety of potential applications, particularly in the transportation industry, including for example, aerospace, marine and automotive applications. Thus, referring now toFIGS. 33 and 34, embodiments of the disclosure may be used in the context of an aircraft manufacturing and service method200as shown inFIG. 33and an aircraft202as shown inFIG. 34. During pre-production, exemplary method200may include specification and design204of the aircraft202and material procurement206. During production, component and subassembly manufacturing208and system integration210of the aircraft202takes place. Thereafter, the aircraft202may go through certification and delivery212in order to be placed in service214. While in service by a customer, the aircraft202is scheduled for routine maintenance and service216(which may also include modification, reconfiguration, refurbishment, and so on).

As shown inFIG. 34, the aircraft202produced by exemplary method200may include an airframe218with a plurality of systems220and an interior222. Examples of high-level systems220include one or more of a propulsion system224, an electrical system226, a hydraulic system228, and an environmental system230. Any number of other systems may be included. Although an aerospace example is shown, the principles of the disclosure may be applied to other industries, such as the marine, automotive and construction industries.

Systems and methods embodied herein may be employed during any one or more of the stages of the production and service method200. For example, components or subassemblies corresponding to production process200may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft202is in service. Also, one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized during the production stages208and210, for example, by substantially expediting assembly of or reducing the cost of an aircraft202. Similarly, one or more of apparatus embodiments, method embodiments, or a combination thereof may be utilized while the aircraft202is in service, for example and without limitation, to maintenance and service216.

Although the embodiments of this disclosure have been described with respect to certain exemplary embodiments, it is to be understood that the specific embodiments are for purposes of illustration and not limitation, as other variations will occur to those of skill in the art. For example, while the disclosed embodiments illustrate a wing, other structures forming part of an aircraft may advantageously employ the disclosed features, such as, for example and without limitation, fuselage sections, especially where the design load on the fuselage varies, as in tapered sections of the fuselage.