Composite structures having reduced area radius fillers and methods of forming the same

A composite structure having a base charge and an outer channel charge is provided. The outer channel charge has an inner radius and an outer radius. A charge of plies adjacent to the inner radius reduces the inner radius.

BACKGROUND

1) Field of the Disclosure

The disclosure relates generally to composite structures and methods of forming the same, and more specifically, to composite structures having reduced area radius fillers and methods of forming the same, such as for stringer composite structures in aircraft wings.

2) Description of Related Art

Composite structures are used in a wide variety of applications, including in the manufacture of aircraft, spacecraft, rotorcraft, watercraft, automobiles, trucks, and other vehicles and structures, due to their high strength-to-weight ratios, corrosion resistance, and other favorable properties. In aircraft construction, composites structures are used in increasing quantities to form the wings, fuselage, tail sections, and other components.

For example, aircraft wings may be formed of composite stiffened panel structures comprising composite skin panels or webs to which reinforcing stiffeners or “stringers” may be attached or bonded to improve the strength, stiffness, buckling resistance, and stability of the composite skin panels or webs. The stringers attached or bonded to the composite skin panels or webs may be configured to carry various loads and may be provided in a variety of different cross-sectional shapes, such as I-beams, T-stiffeners, and J-stiffeners.

Known stringers found in aircraft composite wing structures may have a low pull-off strength. Consequently, such stringers may not be loaded through a stringer blade portion. This may require that holes be drilled in the wing skin and that fasteners be attached through the wing skin to attach, for example, wing rib fittings to the wing skin. However, this may create additional areas on the aircraft subject to possible fuel leaks or manufacturing issues and complications.

Moreover, such fasteners may need to be treated and triple protected for lightening strike protection, and such fastener holes may require liquid tight sealing so that they are not subject to fuel leaks. For example, such fasteners protruding into a fuel cell in the wing may need to be countersunk, coated on the outside with an insulating plug, coated on the inside with an insulating sealant, and grounded to prevent sparking inside of the fuel cell. The time required for installing such fasteners may be increased, which, in turn, may increase manufacturing complexity and cost. In addition, the presence of additional fasteners may add weight to the aircraft, which, in turn, may reduce the payload capacity of the aircraft and may increase fuel consumption, which may result in increased fuel costs.

Void regions may be formed by the radius of curved portions of the stringers when they are attached or joined perpendicularly to composite skin panels or webs. Such void regions may typically be referred to as “radius filler regions” or “noodles”. Such radius filler regions or noodles within stringers may be prone to cracking because they may be three-dimensionally constrained. Radius fillers or noodles made of composite material or adhesive/epoxy material and having a generally triangular cross-section may be used to fill the radius filler regions or noodles in order to provide additional structural reinforcement to such regions. However, known radius fillers or noodles may be made of a material that is different from or not compatible with the material of the composite structure surrounding the radius filler or noodle. This may result in different material properties which may, in turn, require modifications to cure cycles, processing temperatures and pressures, and/or relative amounts of fibers and resin matrices. Such modifications may increase manufacturing time, labor and costs.

A difference in coefficients of thermal expansion (CTE) of the radius filler or noodle material and the material of the composite structure surrounding the radius filler or noodle may cause the radius filler or noodle to be susceptible to thermal cracking. In addition, known unidirectional tape radius fillers or noodles may be susceptible to thermal cracking after curing, if a stiffener cross-sectional area becomes very large. For example, known designs using one large radius filler or noodle may be susceptible to cracking due to increased CTE differences between the large radius filler and the surrounding laminate structure.

To prevent such known unidirectional tape radius fillers or noodles from thermal cracking, the unidirectional tape radius fillers or noodles may be wrapped in fabric to prevent the thermal cracking from spreading to surrounding structures. However, such fabric may need to be applied manually to the surrounding structure, such as the stringer, and this may result in additional manufacturing time, labor, and costs, as well as an increase in possible errors.

Further, known unidirectional/laminate radius fillers or noodles may have relatively blunt tips on the three corners of the radius filler or noodle. A zero degree (0°) ply of pre-preg (i.e., reinforcement fibers impregnated with a resin material) may be folded over itself repeatedly to form a circular radius filler or noodle. The radius filler or noodle may then be formed into a triangular shape under heat and vacuum. The blunt noodle tip may create resin rich pockets at the tips of the radius filler or noodle, and such regions may be susceptible to initiation of crack propagation. The crack may spread between composite plies and the crack may cause premature stringer pull-off strength issues. A low pull-off strength may prevent the stringers from being used as structural attachment points inside the wing box. This, in turn, may require, as discussed above, that holes be drilled in the wing skin and that fasteners be attached through the wing skin to attach wing rib fittings to the wing skin.

Accordingly, there is a need in the art for composite structures having reduced area radius fillers and methods of forming the same that provide advantages over known structures and methods.

SUMMARY

This need for composite structures having reduced area radius fillers and methods of forming the same is satisfied. As discussed in the below detailed description, embodiments of the composite structures having reduced area radius fillers and methods of forming the same may provide significant advantages over known structures and methods.

In one embodiment of the disclosure, there is provided a composite structure. The composite structure comprises a base charge and an outer channel charge. The outer channel charge has an inner radius and an outer radius. The composite structure further comprises a charge of plies adjacent to the inner radius that reduce the inner radius.

In another embodiment of the disclosure, there is provided an aircraft. The aircraft comprises a fuselage and at least one wing coupled to the fuselage. The at least one wing has a composite structure. The composite structure comprises a base charge and an outer channel charge, wherein the outer channel charge has an inner radius and an outer radius. The composite structure further comprises a charge of plies adjacent to the inner radius that reduce the inner radius.

In another embodiment of the disclosure, there is provided a method for forming a composite structure having a reduced area radius filler. The method comprises the step of forming an outer channel charge having a web portion, a flange portion, and a radius filler region, wherein the outer channel charge has in inner radius and an outer radius.

The method further comprises the step of joining the web portion of the outer channel charge to a base charge. The method further comprises the step of adding a charge of plies adjacent to the inner radius to reduce the inner radius. The method further comprises the step of coupling to the radius filler region a radius filler having a radius that substantially corresponds to the reduced inner radius. The method further comprises the step of processing the composite structure to form a composite structure having the reduced area radius filler.

DETAILED DESCRIPTION

Disclosed embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all of the disclosed embodiments are shown. Indeed, several different embodiments may be provided and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and will fully convey the scope of the disclosure to those skilled in the art.

Now referring to the Figures,FIG. 1is an illustration of a perspective view of an exemplary composite structure12having a reduced area radius filler10that may be formed with an embodiment of a method150(seeFIG. 10) of the disclosure. In one embodiment of the disclosure, there is provided the composite structure12(seeFIG. 1). Preferably, the composite structure12(seeFIG. 1) comprises a composite stiffener14, such as an I-section composite stiffener14ahaving a generally I-shaped cross-section. The composite structure12(seeFIG. 1) comprises a base charge32(seeFIG. 1) and an outer channel charge18a(seeFIG. 1). The outer channel charge18a(seeFIG. 1) has an inner radius26(seeFIG. 1) and an outer radius27(seeFIG. 1). The base charge32(seeFIG. 1) and the outer channel charge18a(seeFIG. 1) preferably comprise composite structures12for an aircraft200a(seeFIG. 11). The composite structure12(seeFIG. 1) further comprises a charge of plies60(seeFIGS. 2-7) adjacent to the inner radius26(seeFIG. 1) that reduce the inner radius26(seeFIG. 1).

As shown inFIG. 1, the composite structure12may further comprise an inner channel charge18badjacent to the outer channel charge.18a. Preferably, the outer channel charge18aand the inner channel charge18bcomprise inner C-channel charge19aand outer C-channel charge19b, each having a respective C-shaped cross-section23a,23b. As further shown inFIG. 1, the outer channel charge18aand the inner channel charge18beach have a web portion20, and a pair of oppositely facing flanges22,24. Each of the web portions20(seeFIG. 1) transitions to one of the flanges22,24(seeFIG. 1) at an inner radius26(seeFIG. 1) and at an outer radius27(seeFIG. 1). The web portions20(seeFIG. 1) are joined together to form a web21(seeFIG. 1).

The composite stiffener14(seeFIG. 1) may be used to stiffen a structural member16(seeFIG. 1), such as a wing skin panel16a(seeFIG. 1), of a wing208(seeFIG. 11) of an air vehicle200(seeFIG. 11), such as an aircraft200a(seeFIG. 11). The composite stiffener14(seeFIG. 1) may also be used to stiffen a wing stringer or other component of the wing208(seeFIG. 11) or a skin panel of a fuselage202(seeFIG. 11) section of the aircraft200a(seeFIG. 11).

As further shown inFIG. 1, a cap28is joined to outer surfaces30of the flanges22, and a base charge32is joined to outer surfaces34of the flanges24. The cap28(seeFIG. 1) is bonded to the structural member16(seeFIG. 1), such as wing skin panel16a(seeFIG. 1), in the form of an upper wing skin panel, at an interface35a(seeFIG. 1). The base charge32(seeFIG. 1) is bonded to the structural member16(seeFIG. 1), such as wing skin panel16a(seeFIG. 1), in the form of a lower wing skin panel, at an interface35b(seeFIG. 1).

As further shown inFIG. 1, a radius filler region36having a generally triangular shape38is shown at each intersection of the radii26with the cap28and the base charge32. The reduced area radius filler10(seeFIG. 1) comprises a radius filler11(seeFIG. 1), also referred to interchangeably herein as a “noodle”. Each radius filler region36(seeFIG. 1) is filled with the radius filler11or noodle. The radius filler11has a radius40and cross-sectional shape that substantially corresponds to a generally triangular cross-section42of the radius filler region36.

FIG. 2is an illustration of a front partial sectional view of an embodiment of a reduced area radius filler10, such as in the form of reduced area radius filler10a, having a full ply fabric and adhesive inner wrap52, and that may be used in the composite structure12(seeFIG. 1) formed with an embodiment of the method150(seeFIG. 10) of the disclosure.

FIG. 2shows the outer channel charge18aand the inner channel charge18bwith the web portions20forming the web21and transitioning to the flanges24at the inner radius26and at the outer radius27.FIG. 2further shows the base charge32and the radius filler11in the radius filler region36. Known construction processes may create an inner radius26(seeFIG. 2) larger than the outer radius27(seeFIG. 2), whereas the embodiment shown inFIG. 2may create an inner radius26equal to or smaller than the outer radius.

As shown inFIG. 2, in this embodiment, the reduced area radius filler10, such as in the form of reduced area radius filler10a, comprises radius filler charges44comprised of a charge of plies60, a reduced base charge32a, and a full ply fabric and adhesive inner wrap52. The radius filler charges44(seeFIG. 2) may comprise radial side local material44a(seeFIG. 2) positioned along each side of radii26(seeFIG. 2) of the radius filler11(seeFIG. 2), and may further comprise base side local material44b(seeFIG. 2) positioned along a base side of the radius filler11(seeFIG. 2).

Each ply60or charge of plies60may comprise continuous plies either individually interspersed or stacked composite plies, such as in a form comprising a prepreg unidirectional tape, a unidirectional fiber tape, a carbon fiber-reinforced plastic (CFRP) tape, a carbon fiber-reinforced plastic (CFRP) fabric, a prepreg fabric, a woven fabric including a woven carbon fiber fabric, a combination thereof, or another suitable composite material. In addition, materials such as glass fabric reinforced plastic (GFRP) or metallic pieces, such as of titanium, aluminum, steel or another suitable metal may be used.

The reduced base charge32a(seeFIG. 2) may comprise base filler charges46(seeFIG. 2) comprising base charge local composite plies48positioned along the interface of the base charge32and the base side local material44b(seeFIG. 2) along the base side of the radius filler11(seeFIG. 2). The charge of plies60(seeFIG. 2) in the base charge32adjacent to the outer channel charge18a(seeFIG. 2) further reduces the inner radius26(seeFIG. 2).

The position of the radius filler11(seeFIG. 2) or noodle may preferably be controlled by a thickness of the base filler charges46(seeFIG. 2) versus a thickness of the radius filler charges44(seeFIG. 2). The radius filler charges44(seeFIG. 2) may have a quasi-layup with a full ply fabric, which provides a high toughness.

As shown inFIG. 2, preferably the reduced area radius filler10, such as in the form of reduced area radius filler10a, comprises an interleaved ply configuration50. The full ply fabric and adhesive inner wrap52(seeFIG. 2) is preferably applied with an adhesive layer54(seeFIG. 2) to the outer surfaces34(seeFIG. 2) of the flanges24(seeFIG. 2) between the flanges24(seeFIG. 2) and the base charge32(seeFIG. 2), at web21(seeFIG. 2) between the web portions20(seeFIG. 2) of the outer channel charge18a(seeFIG. 2) and the inner channel charge18b(seeFIG. 2), and around the radius filler11(seeFIG. 2) or noodle. The fabric and adhesive inner wrap52(seeFIG. 2) may be applied between the base charge32(seeFIG. 2) and the outer channel charge18a(seeFIG. 2) and applied adjacent to the inner radius26(seeFIG. 2) to further reduce the inner radius26(seeFIG. 2).

The radius filler11(seeFIG. 2) or noodle may comprise a uni-noodle, a laminate noodle, a rolled fiberglass fabric noodle, a titanium extruded noodle, or another suitable noodle. The radius filler11(seeFIG. 2) or noodle is preferably positioned at a center interface portion56(seeFIG. 2) surrounded by the radius filler charges44(seeFIG. 2) and the full ply fabric and adhesive inner wrap52(seeFIG. 2).

FIG. 3is an illustration of a front partial sectional view of an embodiment of a reduced area radius filler10, such as in the form of reduced area radius filler10b, having interlaminar fillers58of individual plies60interspersed in the radius26of the reduced area radius filler10, such as in the form of reduced area radius filler10b, and that may be used in the composite structure12(seeFIG. 1) formed with an embodiment of the method150(seeFIG. 10) of the disclosure.

FIG. 3shows the outer channel charge18aand the inner channel charge18bwith the web portions20joining at web21and transitioning to the flanges24at the inner radius26and at the outer radius27.FIG. 3further shows the base charge32and the radius filler11in the radius filler region36. As shown inFIG. 3, in this embodiment, the reduced area radius filler10, such as in the form of reduced area radius filler10b, comprises interlaminar fillers58comprising individual plies60having either a +45 degree ply orientation62or a −45 degree ply orientation64. As shown inFIG. 3, preferably the reduced area radius filler10, such as in the form of reduced area radius filler10a, comprises an interleaved ply configuration50.

FIG. 4is an illustration of a front partial sectional view of an embodiment of a reduced area radius filler10, such as in the form of reduced area radius filler10c, having a reduced volume extruded radius filler66, and that may be used in a composite structure12(seeFIG. 1) formed with an embodiment of the method150(seeFIG. 11) of the disclosure.

FIG. 4shows the outer channel charge18aand the inner channel charge18beach with the web portions20joining at web21and transitioning to the flanges24at the inner radius26and at the outer radius27.FIG. 4further shows the base charge32and the radius filler11in the radius filler region36. The inner radius26(seeFIG. 4) may have a radial measurement that is smaller in dimension than the outer radius27(seeFIG. 2). As shown inFIG. 4, in this embodiment, the volume of the extruded radius filler11or noodle is significantly reduced and approaches the embodiment of a no radius filler or noodle embodiment, discussed below in connection withFIG. 7.

FIG. 5is an illustration of a front partial sectional view of an embodiment of a reduced area radius filler10, such as in the form of reduced area radius filler10d, having multiple pockets68of radius filler charges44, and that may be used in the composite structure12(seeFIG. 1) formed with an embodiment of the method150(seeFIG. 10) of the disclosure.

FIG. 5shows the outer channel charge18aand the inner channel charge18bwith the web portions20joining at web21and transitioning to the flanges24at the inner radius26and at the outer radius27.FIG. 5further shows the base charge32and the radius filler11in the radius filler region36.

As shown inFIG. 5, in this embodiment, the reduced area radius filler10, such as in the form of reduced area radius filler10d, comprises the multiple pockets68of radius filler charges44comprising a charge of plies60of radial side local material44ahaving either a (+45/90/−45) degree ply orientation70or a (−45/901+45) degree ply orientation72. In this embodiment, the outer channel charge18aand the inner channel charge18bcomprise interlaminar layers74, where each of the outer channel charge18aand the inner channel charge18bhas an inner channel charge76aand an outer channel charge76b. The multiple pockets68(seeFIG. 5) of the charge of plies60(seeFIG. 5) may be interleaved throughout or adjacent the inner radius26(seeFIG. 5), to further reduce the inner radius26(seeFIG. 5).

FIG. 6is an illustration of a front partial sectional view of an embodiment of a reduced area radius filler10, such as in the form of reduced area radius filler10e, having inner channel charges76aand outer channel charges76b, radius filler charges44, and a full ply fabric and adhesive inner wrap52, and that may be used in the composite structure12(seeFIG. 1) formed with an embodiment of the method150(seeFIG. 10) of the disclosure.

FIG. 6shows the outer channel charge18aand the inner channel charge18bwith the web portions20transitioning to the flanges24at the inner radius26and at the outer radius27.FIG. 6further shows the base charge32, such as in the form of reduced base charge32a, and the radius filler11in the radius filler region36. The inner radius26(seeFIG. 6) may have a radial measurement equal to or smaller than the outer radius27(seeFIG. 6). One embodiment may consist of radial side local material44a(seeFIGS. 2, 6) and base side local material44b(seeFIG. 2) consisting of various composite materials, such as carbon-fiber reinforced plastic (CFRP) or glass fabric reinforced plastic (GFRP), or metallic pieces, such as of titanium, aluminum, steel, or another suitable metal.

As shown inFIG. 6, in this embodiment, the reduced area radius filler10, such as in the form of reduced area radius filler10e, comprises radius filler charges44, a reduced base charge32a, and a full ply fabric and adhesive inner wrap52. The radius filler charges44(seeFIG. 6) may comprise radial side local material44a(seeFIG. 6) positioned in the radius26(seeFIG. 6) of the radius filler11(seeFIG. 6). The radius filler charges44(seeFIG. 6) may have a quasi-layup with minimal 0's (zero degree plies), for example, 10 plies.

In this embodiment, the outer channel charge18aand the inner channel charge18b(seeFIG. 6) each comprise an inner channel charge76a(seeFIG. 6) of about 15 plies, and an outer channel charge76b(seeFIG. 6) of about 15 plies. The radial side local material44a(seeFIG. 6) positioned of the radius filler charges44(seeFIG. 6) may comprise short plies78(seeFIG. 6) and long plies80(seeFIG. 6). The radial side local material44a(seeFIG. 6) may be interspersed from short plies78(seeFIG. 6) to long plies80(seeFIG. 6) or from long plies80(seeFIG. 6) to short plies78(seeFIG. 6).

FIG. 7is an illustration of a front partial sectional view of another embodiment of a reduced area radius filler10, such as in the form of reduced area radius filler10f, having interlaminar filler segments58comprised of individual plies60interspersed in areas81(seeFIG. 7) between radii27(seeFIG. 7). The reduced area radius filler10f(seeFIG. 7) may be used in the composite structure12(seeFIG. 1) formed with an embodiment of the method150(seeFIG. 10) of the disclosure.FIG. 7shows the web21, the flanges24, the outer radius27, the interlaminar layers74, the structural member16such as in the form of a stringer charge or skin16b, and individual plies60.

In this embodiment, the reduced area radius filler10, such as in the form of reduced area radius filler10f, preferably comprises a segmented interlaminate radius filler (SIRF)82that has no radius filler11(seeFIG. 1) or noodle. The segmented interlaminate radius filler (SIRF)82(seeFIG. 7) divides a vertical pull-off load between several interlaminar layers74(seeFIG. 7) and between individual plies60(seeFIG. 7) at a T-section radius83(seeFIG. 7). The innermost ply60a(seeFIG. 7) forms the T-section radius83(seeFIG. 7), and subsequent interlaminar layers74(seeFIG. 7) gradually form larger and larger radii84(seeFIG. 7) by using the interlaminar filler segments58to create a void85at a vertex86of the corners of the SIRF82(seeFIG. 7).

The SIRF82(seeFIG. 7) is preferably configured to place interlaminar filler segments58between the charge of plies60(seeFIG. 7) to space the charge of plies60(seeFIG. 7) away from each other to create a T-section radius83(seeFIG. 7). The interlaminar filler segments58(seeFIG. 7) preferably comprise chopped fibers, tape plies including unidirectional tape, fabric plies, fiberglass, continuous plies, metallic pieces, a combination thereof, or any other suitable material that sufficiently bonds to the surrounding structural member16(seeFIG. 7), such as stringer plies61(seeFIG. 7) of a stringer charge or skin16b(seeFIG. 7).

The SIRF82(seeFIG. 7) preferably uses short strips of the interlaminar filler segments58(seeFIG. 7) in order to transition from a square corner87(seeFIG. 7) of the innermost ply60a(seeFIG. 7) to a satisfactory radius27at the outermost ply60b(seeFIG. 7). The interlaminar filler segments58(seeFIG. 7) preferably spaces the individual plies60(seeFIG. 7) away from each other creating an appropriate T-section radius83(seeFIG. 7). The small, short sections of interlaminar filler segments58(seeFIG. 7) create a smooth CTE (coefficient of thermal expansion) interchange between the outermost plies60b(seeFIG. 7) and the short sections of interlaminar filler segments58(seeFIG. 7). The thin nature of the interlaminar filler segments58(seeFIG. 7) do not create resin rich pockets, and the pull-off load is allowed to be spread more evenly into the stringer charge or skin16b(seeFIG. 7) by spreading a stringer charge interface89(seeFIG. 7) into a larger area than previous designs.

The interlaminar filler segments58(seeFIG. 7) may be applied between every stringer tape ply in the stringer charge or skin16b(seeFIG. 7), but it may also be applied between multiple stringer plies61in the stringer charge or skin16b(seeFIG. 7), if necessary. The SIRF82(seeFIG. 7) preferably splits the load out across a larger area by splitting up the stringer plies61by using several small interlaminar filler segments58(seeFIG. 7) to achieve this effect. Previous designs used one large radius filler which tended to crack because of the large CTE differences between the large radius filler and the surrounding laminate, whereas the SIRF82(seeFIG. 7) uses small interlaminar filler segments58(seeFIG. 7) to minimize the difference in CTE. The stringer charge interface89(seeFIG. 7), such as in the form of a bond line89abetween the stringer charge or skin16band the reduced area radius filler10f(seeFIG. 7), is also not as critical in the SIRF82(seeFIG. 7), since several less critical bond lines may be used in place of one bond line used with such known radius filler.

The SIRF82(seeFIG. 7) distributes the load more evenly into the stringer charge or skin16b(seeFIG. 7), reduces the CTE mismatch between the stringer charge or skin16b(seeFIG. 7) and the radius filler11(seeFIG. 1) or noodle, and may reduce the importance of the single stringer to noodle bond line89aused for known radius fillers or noodles by using several less critical bond lines.

FIG. 8Ais an illustration of a schematic diagram of an embodiment of a radius filler fabrication process90, such as in the form of radius filler fabrication process90a, that may be used in forming the reduced area radius filler10(seeFIGS. 1-7) of the composite structure12(seeFIG. 1) by laying up with a mandrel96.FIG. 8Bis an illustration of a schematic diagram of another embodiment of a radius filler fabrication process90, such as in the form of radius filler fabrication process90b, that may be used in forming the reduced area radius filler10(seeFIGS. 1-7) of the composite structure12(seeFIG. 1) by laying up with a radius filler11or noodle.

As shown inFIGS. 8A-8B, a composite laminate stackup92is stacked on a forming tool100and the composite laminate stackup92is deformed when a downward force98is applied to the composite laminate stackup92, and deformed plies94are formed with shorter plies94aabove an ultrasonic knife cut102and longer plies94bbelow the ultrasonic knife cut102. The deformed plies94may be laid up on the mandrel (seeFIG. 8A) or may be laid up to form a radius filler11or noodle (seeFIG. 8B).

FIG. 9Ais a back perspective view of a wing208of an aircraft200a(seeFIG. 11) that incorporates a structural member16, such as an upper trailing edge panel16c, on the wing208. The upper trailing edge panel16c(seeFIG. 9A) may have a reduced area radius filler10, such as in the form of reduced area radius filler10g.

FIG. 9Bis an enlarged top view of the structural member16, such as upper trailing edge panel16cofFIG. 9A. As shown inFIG. 9A, the upper trailing edge panel16ccomprises an inner skin106, an outer skin108, a core110, and an edge band112. A ply sequence104for the upper trailing edge panel16cis also shown inFIG. 9B.

FIG. 9Cis a cross-sectional view of a core ramp down114of the upper trailing edge panel16ctaken along lines9C-9C ofFIG. 9B. The core ramp down114of the upper trailing edge panel16cofFIG. 9Cshows the inner skin106, the outer skin108, the core110such as a honeycomb core110a, the edge band112, and a core ramp down114having a top end116and a bottom end118. With core ramp downs, a large peel load may occur at the bottom118of the core ramp down114, and reinforcing filler material120may be integrated in corners122of interlaminar layers124of the core ramp down114in order to reinforce the core ramp down114.

FIG. 10is an illustration of a flow diagram of an embodiment of a method150of the disclosure. As shown inFIG. 10, there is provided the method150for forming the composite structure12(seeFIG. 1) having a reduced area radius filler10(seeFIGS. 1-7).

As shown inFIG. 10, the method150comprises step152of forming an outer channel charge18a(seeFIG. 1) having a web portion20(seeFIG. 1), flange portions22,24(seeFIG. 1), and a radius filler region36(seeFIG. 1), wherein the outer channel charge18a(seeFIG. 1) has in inner radius26(seeFIG. 1) and an outer radius27(seeFIG. 1).

As further shown inFIG. 10, the method150further comprises step154of joining the web portion20(seeFIG. 1) of the outer channel charge18a(seeFIG. 1) to a base charge32(seeFIG. 1).

As shown inFIG. 10, the method150further comprises step156of adding a charge of plies60(seeFIG. 6) adjacent to the inner radius26(seeFIG. 6) to reduce the inner radius26(seeFIG. 6). The step156of adding the charge of plies60(seeFIG. 6) adjacent to the inner radius26(seeFIG. 6) to reduce the inner radius26(seeFIG. 6) comprises interleaving multiple pockets68(seeFIG. 5) of ply charges60(seeFIG. 5) throughout or adjacent the inner radius26(seeFIG. 5), that further reduce the inner radius26(seeFIG. 5).

As shown inFIG. 10, the method150further comprises step158of coupling to the radius filler region36(seeFIG. 1) a radius filler11(seeFIG. 1) having a radius40(seeFIG. 1) that substantially corresponds to the reduced inner radius26(seeFIG. 1).

As shown inFIG. 10, the method150further comprises step160of processing the composite structure12(seeFIG. 1) to form a composite structure12(seeFIG. 1) having the reduced area radius filler10(seeFIG. 1). Known forming processes such as a hot drape forming process, a pultrusion forming process, or another suitable forming process may be used.

As further shown inFIG. 10, the method150may optionally comprise prior to step160of processing the composite structure12(seeFIG. 1), the optional step162of joining an inner channel charge18b(seeFIG. 1) adjacent to the outer channel charge18a(seeFIG. 1).

The method150may further comprise using a segmented interlaminate radius filler82(seeFIG. 7) configured to place interlaminar filler segments58(seeFIG. 7) between the charge of plies60(seeFIG. 7) to space the charge of plies60(seeFIG. 7) away from each other to create a T-section radius83(seeFIG. 7).

The method150may further comprise the step prior to step160(seeFIG. 10) of processing the composite structure12(seeFIG. 1), the step of adding a charge of plies60(seeFIG. 2) in the base charge32(seeFIG. 2) adjacent to the outer channel charge18a(seeFIG. 2) that further reduce the inner radius26(seeFIG. 2).

The method150may further comprise the step prior to step160of processing the composite structure12(seeFIG. 1), the step of applying a fabric and adhesive inner wrap52(seeFIG. 2) between the base charge32(seeFIG. 2) and the outer channel charge18a(seeFIG. 2), and applying adjacent to the inner radius26(seeFIG. 2) to further reduce the inner radius26(seeFIG. 2).

In another embodiment of the disclosure, there is provided an aircraft200a(seeFIG. 11). The aircraft200a(seeFIG. 11) comprises a fuselage202(seeFIG. 11) and at least one wing208(seeFIG. 11) coupled to the fuselage202. The at least one wing208has a composite structure12(seeFIG. 1). The composite structure12(seeFIG. 1) comprises a base charge32(seeFIG. 1) and an outer channel charge18a(seeFIG. 1), wherein the outer channel charge18a(seeFIG. 1) has an inner radius26(seeFIG. 1) and an outer radius27(seeFIG. 1). The composite structure12(seeFIG. 1) further comprises a charge of plies60(seeFIG. 1) adjacent to the inner radius26(seeFIG. 1) that reduce the inner radius26(seeFIG. 1).

The composite structure12(seeFIG. 1) of the aircraft200a(seeFIG. 11) may further comprise an inner channel charge18b(seeFIG. 1) adjacent to the outer channel charge18a(seeFIG. 1). The composite structure12(seeFIG. 1) of the aircraft200a(seeFIG. 11) may further comprise a segmented interlaminate radius filler82(seeFIG. 7) configured to place interlaminar filler segments58(seeFIG. 7) between the charge of plies60(seeFIG. 7) to space the charge of plies60away from each other to create a T-section radius83(seeFIG. 7).

The composite structure12(seeFIG. 1) of the aircraft200a(seeFIG. 11) may further comprise a charge of plies60(seeFIG. 2) in the base charge32(seeFIG. 2) adjacent to the outer channel charge18a(seeFIG. 2) that further reduce the inner radius26(seeFIG. 2). The composite structure12(seeFIG. 1) of the aircraft200a(seeFIG. 11) may further comprise multiple pockets68(seeFIG. 5) of a charge of plies60(seeFIG. 5) interleaved throughout or adjacent the inner radius26(seeFIG. 5), that further reduce the inner radius26(seeFIG. 5).

FIG. 11is an illustration of a perspective view of an air vehicle200, such as an aircraft200a, that may incorporate an exemplary structural member16, such as a wing skin panel16a, having a composite structure12(seeFIG. 1) having a reduced area radius filler10(seeFIGS. 2-7) that may be formed with an embodiment of the method150(seeFIG. 10) of the disclosure. As shown inFIG. 11, the air vehicle200, such as in the form of aircraft200a, comprises a fuselage202, a nose204, a cockpit206, wings208, one or more propulsion units210, a tail212comprising a vertical tail portion214, and horizontal tail portions216.

As shown inFIG. 1, the structural member16may comprise wing skin panels16ain wings18. Although the aircraft200ashown inFIG. 11is generally representative of a commercial passenger aircraft having one or more structural member16, the teachings of the disclosed embodiments may be applied to other passenger aircraft, cargo aircraft, military aircraft, rotorcraft, and other types of aircraft or aerial vehicles, as well as aerospace vehicles, satellites, space launch vehicles, rockets, and other aerospace vehicles, as well as boats and other watercraft, trains, automobiles, trucks, buses, or other suitable structures having one or more structural members16with reduced area radius fillers10and that may be made with one or more embodiments of the method150(seeFIG. 10) disclosed herein.

FIG. 12is an illustration of a flow diagram of an aircraft production and service method300.FIG. 13is an illustration of a functional block diagram of an aircraft320. Referring toFIGS. 12-13, embodiments of the disclosure may be described in the context of the aircraft manufacturing and service method300, as shown inFIG. 12, and the aircraft320, as shown inFIG. 13. During pre-production, the exemplary aircraft manufacturing and service method300(seeFIG. 12) may include specification and design302(seeFIG. 12) of the aircraft316(seeFIG. 8) and material procurement304(seeFIG. 12). During manufacturing, component and subassembly manufacturing306(seeFIG. 12) and system integration308(seeFIG. 12) of the aircraft316(seeFIG. 13) takes place. Thereafter, the aircraft316(seeFIG. 13) may go through certification and delivery310(seeFIG. 12) in order to be placed in service312(seeFIG. 12). While in service312(seeFIG. 12) by a customer, the aircraft316(seeFIG. 13) may be scheduled for routine maintenance and service314(seeFIG. 12), which may also include modification, reconfiguration, refurbishment, and other suitable services.

As shown inFIG. 8, the aircraft320produced by the exemplary aircraft manufacturing and service method300may include an airframe322with a plurality of systems324and an interior326. As further shown inFIG. 8, examples of the systems324may include one or more of a propulsion system328, an electrical system330, a hydraulic system332, and an environmental system334. 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 automotive industry.

Methods and systems embodied herein may be employed during any one or more of the stages of the aircraft manufacturing and service method300(seeFIG. 12). For example, components or subassemblies corresponding to component and subassembly manufacturing306(seeFIG. 12) may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft320(seeFIG. 13) is in service312(seeFIG. 12). Also, one or more apparatus embodiments, method embodiments, or a combination thereof, may be utilized during component and subassembly manufacturing306(seeFIG. 12) and system integration308(seeFIG. 12), for example, by substantially expediting assembly of or reducing the cost of the aircraft320(seeFIG. 13). Similarly, one or more of apparatus embodiments, method embodiments, or a combination thereof, may be utilized while the aircraft320(seeFIG. 8) is in service312(seeFIG. 12), for example and without limitation, to maintenance and service312(seeFIG. 12).

Disclosed embodiments of the reduced area radius filler10(seeFIGS. 2-7) and the method150(seeFIG. 10) provide for composite structures12(seeFIG. 1) having reduced area radius fillers10and interlaminar layers74formed of interlaminar filler segments58(seeFIG. 7). The novelty resides in the local composite plies60(seeFIG. 2-3, 5-7) added to the multiple outer channel charges18a(seeFIG. 1) and base charges32(seeFIG. 1) that results in a noodle cross sectional area that is divorced from the channel inner radius26(seeFIG. 1) and web laminate thickness. Adding plies60(seeFIGS. 2-3) reduces the outer radius27(seeFIG. 1) making the radius filler11or noodle smaller. Interleaved plies50(seeFIG. 2) between the outer channel charge18a(seeFIG. 1) and the inner channel charge18b(seeFIG. 1) to reduce the size of the required radius filler11or noodle.

In addition, disclosed embodiments of the reduced area radius filler10(seeFIGS. 2-7) and the method150(seeFIG. 10) provide for reduced airframe weight and cost associated with reduced reinforcement requirements, reduced cost of composite inspections, significant amounts of time during the assembly of each composite wing, each wing could save a significant amount of weight by reducing the number of fasteners through the skin and by eliminating the associated lightening strike protection for each of the removed fasteners. Moreover, the number of protrusions through the fuel cell may be reduced. Fewer holes may reduce future possibilities of fuel leakage. Long term composite wing durability may be greatly increased by the improved thermal properties of the SIRF noodle. This reduced area radius filler10(seeFIGS. 1-7) may distribute the load more evenly into the skin charge, reduce the CTE mismatch between the stringer charge and the radius filler11or noodle, and will reduce the importance of the single stringer to noodle bond line used for known noodles by using several less critical bond lines.

Many modifications and other embodiments of the disclosure will come to mind to one skilled in the art to which this disclosure pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. The embodiments described herein are meant to be illustrative and are not intended to be limiting or exhaustive. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.