Patent Description:
Composite structures are being increasingly used in various platforms, such as, but not limited to, aircraft, unmanned aerial vehicles, and other types of aerospace vehicles. A composite structure may be comprised of at least one composite part made of composite material. In some cases, when two or more composite parts are joined together, channels or voids may be created along the bond lines between these composite parts. These voids may need to be filled in order to increase the strength of the bond. A filler may be used to fill this type of void.

As one example, in the aircraft industry, when a composite stiffener is mated with a composite skin panel, a filler may be used to fill the void created at the radius bond line between the composite stiffener and the composite skin panel. This type of filler may sometimes be referred to as a "composite filler," a "noodle," or a "composite noodle.

Currently used fillers are oftentimes made from materials, such as adhesive, prepreg tape, fabric, or other types of composite materials. Further, fillers are made to have a desired level of stiffness. For example, a filler used between a composite stiffener and a composite skin panel may need to have a certain level of thickness to transfer loads from the composite stiffener to the composite skin panel.

During the manufacturing and operation of an aircraft, composite fillers in the aircraft may experience various forces. These forces may cause undesired inconsistencies to form within these composite fillers. For example, cracks, delamination, and other undesired inconsistencies may develop within a composite material. These types of undesired inconsistencies may prevent the composite filler from transferring loads in the desired manner. Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, such as, but not limited to, preventing cracks in composite fillers, as well as other possible issues.

<CIT> Al states, according to its abstract, that a method of making a composite structure is provided. The method includes the step of applying chopped fiber material in varying thicknesses onto a first ply surface of a first composite charge to form a layered composite charge. The method further includes the step of folding the layered composite charge. The method further includes the step of assembling a second composite charge and the folded layered composite charge to form a composite structure. The chopped fiber material forms a gap filler in the composite structure. The gap filler conforms to a shape of the composite structure surrounding the gap filler. The method further includes processing the composite structure.

Claims <NUM> and <NUM> of <CIT> Al further state:
"<NUM>. A method of making a composite structure, the method comprising the steps of: applying chopped fiber material in varying thicknesses onto a first ply surface of a first composite charge to form a layered composite charge; folding the layered composite charge; assembling a second composite charge and the folded layered composite charge to form a composite structure, the chopped fiber material forming a gap filler in the composite structure, the gap filler conforming to a shape of the composite structure surrounding the gap filler; and, processing the composite structure.

A system for making a composite structure, the system comprising: a layered composite charge comprising: a first composite charge comprising a plurality of first stacked composite plies and having a first ply surface; and, a chopped fiber gap filler layer applied to the first ply surface, the chopped fiber gap filler layer comprising chopped fiber material in varying thicknesses; a composite material processing assembly adapted to fold the layered composite charge; a second composite charge comprising a plurality of second stacked composite plies, the second composite charge being assembled with the folded layered composite charge to form a composite structure; at least one gap filler formed in the composite structure, the gap filler formed of the chopped fiber material comprising a same material as or a compatible material with a material comprising the composite structure surrounding the gap filler, and the gap filler being quasiisotropic and conforming to a shape of the composite structure surrounding the gap filler; at least one interlaminar layer formed in the composite structure, the interlaminar layer formed of the chopped fiber material; and, a vacuum bag assembly and a curing apparatus for processing the composite structure.

<CIT> states, according to its abstract, that a non-woven matrix of glass fibers, synthetic and natural fibers provide a rigid but resilient product having good strength and insulating characteristics. The product may be utilized in a planar configuration or be further formed into complexly curved and shaped configurations. The matrix consists of glass fibers, synthetic fibers such as polyester, nylon or Kevlar and natural fibers of wood or textiles which have been intimately combined with a thermosetting resin into a homogeneous mixture. This mixture is dispersed to form a blanket. A variety of products having varying thickness and rigidity may then be produced by controlling the compressed thickness and the degree of activation of the thermosetting resin. The product may also include a skin or film on one or both faces thereof. An alternate embodiment includes a conductive/coloring agent such as carbon black.

<CIT> states, according to its abstract, that a method and apparatus of forming a preform of structural fibers include a hermetically sealed housing for controlling air pressures and flow therein. A perforated screen is located within the housing separating same into a high pressure chamber and a low pressure chamber. Pressurized air is supplied to the high pressure chamber to agitate and randomize fibers, and a vacuum is provided in the low pressure chamber to draw and compact the fibers against the screen. The pressure differential between the chambers provides significant compaction of the fibers against the screen. A binder is applied to the fibers to maintain the shape of the preform.

According to the present disclosure, an apparatus, and a method as defined in the independent claims are provided. Further embodiments of the claimed invention are defined in the dependent claims. Although the claimed invention is only defined by the claims, the below embodiments, examples, and aspects are present for aiding in understanding the background and advantages of the claimed invention.

The novel features believed characteristic of the illustrative aspects are set forth in the appended claims. The illustrative aspects, 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 aspect of the present disclosure when read in conjunction with the accompanying drawings, wherein:.

The illustrative aspects recognize and take into account different considerations. For example, the illustrative aspects recognize and take into account that it may be desirable to have a method and apparatus for manufacturing a composite filler that results in the composite filler having a desired resistance to undesired inconsistencies, such as cracking. The illustrative aspects recognize and take into account that a composite filler made up of randomly oriented discontinuous filaments that are comprised of a stiffening material and discontinuous filaments that are comprised of a binding material may help improve the stiffness, toughness, and stability of the composite filler.

Thus, the illustrative aspects provide a method and apparatus for manufacturing a composite filler that comprises a fiber matrix that is uniform in all directions in three dimensions. In one illustrative example, the fiber matrix may comprise a first plurality of discontinuous filaments and a second plurality of discontinuous filaments. Each filament of the first plurality of discontinuous filaments may be comprised of a stiffening material and each filament of the second plurality of discontinuous filaments may be comprised of a binding material. Filaments of both the first plurality of discontinuous filaments and the second plurality of discontinuous filaments may be randomly oriented and entangled with each other.

Referring now to the figures and, in particular, with reference to <FIG>, an illustration of a manufacturing environment is depicted in the form of a block diagram in accordance with an illustrative aspect. Manufacturing environment <NUM> may be an example of one environment in which composite structure <NUM> may be manufactured.

Composite structure <NUM> may be used in various different types of platforms. In one illustrative example, composite structure <NUM> may be used in aerospace vehicle <NUM>. Aerospace vehicle <NUM> may take the form of an aircraft, a helicopter, an unmanned aerial vehicle, a space shuttle, a space vehicle, or some other type aerospace vehicle. In other illustrative examples, composite structure <NUM> may be used in a ground vehicle, a water vehicle, a building, or some other type of platform.

Composite structure <NUM> may be comprised of at least two composite parts. For example, without limitation, composite structure <NUM> may include first composite part <NUM> and second composite part <NUM>. A composite part may be comprised of at least one of a ply, a resin-impregnated ply, a dry preform, a resin impregnated preform, or some other type or premanufactured article.

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 the items in the list may be needed. The item may be a particular object, thing, step, operation, process, or category. In other words, "at least one of" means any combination of items or number of items may be used from the list, but not all of the items in the list may be required.

For example, without limitation, "at least one of item A, item B, or item C" or "at least one of item A, item B, and item C" may mean item A; item A and item B; item B; item A, item B, and item C; or item B and item C. In some cases, "at least one of item A, item B, or item C" or "at least one of item A, item B, and item C" may mean, but is not limited to, two of item A, one of item B, and ten of item C; four of item B and seven of item C; or some other suitable combination.

In one illustrative example, first composite part <NUM> and second composite part <NUM> may be made from pre-impregnated fiber preforms. In another illustrative example, first composite part <NUM> and second composite part <NUM> may be made from dry fiber preforms or tacked together dry preforms that may be later infused with resin and cured to form a fully cured composite structure.

When first composite part <NUM> and second composite part <NUM> are mated together, void <NUM> may be formed between these two composite parts. Filler <NUM> may be used to substantially fill void <NUM>. In some cases, filler <NUM> may also be referred to as a composite filler, a noodle, or a composite noodle.

In these illustrative examples, filler <NUM> may be formed such that filler <NUM> has set of filler properties <NUM> that substantially match the set of properties <NUM> of composite structure <NUM>. Set of properties <NUM> includes coefficient of thermal expansion <NUM> and stiffness <NUM>. Filler <NUM> may be formed such that set of filler properties <NUM> includes filler coefficient of thermal expansion <NUM> and filler stiffness <NUM> that substantially match coefficient of thermal expansion <NUM> and stiffness <NUM>, respectively, of composite structure <NUM>. In these illustrative examples, filler <NUM> may be formed such that filler <NUM> also has properties that match set of properties <NUM> of composite structure <NUM>. For example, without limitation, set of properties <NUM> may include at least one of toughness, density, or some other material property.

As depicted, filler <NUM> may be comprised of fiber matrix <NUM>. In some cases, resin <NUM> may be infused in filler <NUM> prior to or after filler <NUM> is collocated with first composite part <NUM> and second composite part <NUM>. Resin <NUM> may help toughen and strengthen filler <NUM>. Fiber matrix <NUM> may take the form of three-dimensional fiber matrix <NUM>. Fiber matrix <NUM> may be comprised of filaments <NUM>. In this illustrative example, filaments <NUM> are discontinuous filaments <NUM>. In some cases, discontinuous filaments <NUM> may also be referred to as chopped fibers.

Discontinuous filaments <NUM> may be fibers that do not extend the entire length or width of filler <NUM>. Discontinuous filaments <NUM> may include filaments of different sizes, different diameters, different cross-sectional shapes, different types, or some combination thereof. In one illustrative example, each of discontinuous filaments <NUM> may have a length of about at least one millimeter.

Further, discontinuous filaments <NUM> may be randomly oriented relative to each other and entangled with each other such that fiber matrix <NUM> is substantially isotropic <NUM>. Being substantially isotropic <NUM> means that fiber matrix <NUM> is uniform in all directions, within selected tolerances. In other words, fiber matrix <NUM> may be substantially invariant with respect to direction.

In one illustrative example, discontinuous filaments <NUM> may include first plurality of discontinuous filaments <NUM> and second plurality of discontinuous filaments <NUM>. Each filament of first plurality of discontinuous filaments <NUM> may be comprised of stiffening material <NUM>. Consequently, in some cases, first plurality of discontinuous filaments <NUM> may also be referred to as a plurality of discontinuous stiffening filaments. Each filament of second plurality of discontinuous filaments <NUM> may be comprised of binding material <NUM>. Consequently, in some cases, second plurality of discontinuous filaments <NUM> may also be referred to as a plurality of discontinuous binding filaments.

The filaments of first plurality of discontinuous filaments <NUM> and second plurality of discontinuous filaments <NUM> may be randomly oriented and entangled with each other such that fiber matrix <NUM> is substantially isotropic <NUM>. In other words, the filaments of first plurality of discontinuous filaments <NUM> and second plurality of discontinuous filaments <NUM> may be randomly oriented and entangled with each other such that fiber matrix <NUM> is uniform in all directions, within selected tolerances.

Stiffening material <NUM> may be comprised of one or more materials that contribute to filler stiffness <NUM>. Stiffening material <NUM> may comprise, for example, without limitation, at least one of carbon, silica, glass, boron, a para-aramid synthetic fiber, a polyimide, a ceramic material, a metallic material or some other type of stiffening material.

Binding material <NUM> may be comprised of one or more materials that help bind discontinuous filaments <NUM> of filler <NUM> together. For example, binding material <NUM> may hold discontinuous filaments <NUM> together in response to at least one of heat, pressure, or a chemical reaction being applied to binding material <NUM>. Binding material <NUM> may also hold discontinuous filaments <NUM> together during handling. Additionally, binding material <NUM> may be used to bind filler <NUM> to composite structure <NUM>. Further, binding material <NUM> may help toughen, stiffen, and stabilize filler <NUM>.

Binding material <NUM> may comprise, for example, without limitation, at least one of a thermoplastic material, a thermoset material, or some other type of binding material. A thermoplastic material may comprise, for example, without limitation, an acrylic material, a fluorocarbon, a polyamide, a polyolefin such as polyethylene or polypropylene, a polyester, a polycarbonate, a polyurethane, a polyaryletherketone, or some other type of thermoplastic material. A thermoset material may comprise, for example, without limitation, a polyurethane, a phenolic material, a polymide, a sulphonated polymer, a conductive polymer, a benzoxazine, a bismaleimide, a cyanate ester, a polyester, an epoxy, a silsesquioxane, or some other type of thermoset material.

In these illustrative examples, fiber matrix <NUM> may be used as filler <NUM> prior to infusing resin <NUM> within fiber matrix <NUM>. In these examples, filler <NUM> may be referred to as dry filler <NUM>. Dry filler <NUM> may be inserted within void <NUM>.

In some cases, first composite part <NUM> and second composite part <NUM> may be dry preforms. After dry filler <NUM> is inserted into void <NUM>, resin <NUM> may be infused within first composite part <NUM>, second composite part <NUM>, and dry filler <NUM> to form composite structure <NUM>, which may then be cured. In some illustrative examples, the same or different types of resin may be infused within each of first composite part <NUM>, second composite part <NUM>, and dry filler <NUM>.

In other cases, first composite part <NUM> and second composite part <NUM> may be pre-impregnated with resin <NUM> but uncured. After dry filler <NUM> is inserted into void <NUM>, resin <NUM> may be infused within dry filler <NUM> located within void <NUM> to form composite structure <NUM>, which may then be cured. Resin <NUM> may be the same or different from the resin impregnated within first composite part <NUM> and second composite part <NUM>.

In other illustrative examples, resin <NUM> may be infused within fiber matrix <NUM> to form filler <NUM> prior to filler <NUM> being inserted within void <NUM>. In these examples, filler <NUM> may be referred to as wet filler <NUM>. As one illustrative example, resin <NUM> may be impregnated within fiber matrix <NUM>. Resin <NUM> may help further toughen and strengthen filler <NUM>. Once resin <NUM> has been infused within fiber matrix <NUM> to form wet filler <NUM>, wet filler <NUM> may be positioned relative to first composite part <NUM> and second composite part <NUM> to fill void <NUM>. Depending on the implementation, first composite part <NUM> and second composite part <NUM> may be dry preforms or resin-infused parts.

In this manner, resin <NUM> may be infused within filler <NUM> prior to the collocation of filler <NUM> with first composite part <NUM> and second composite part <NUM> during the manufacturing of composite structure <NUM>. Alternately, resin <NUM> may also be infused within filler <NUM> after the collocation of filler <NUM> with first composite part <NUM> and second composite part <NUM> during the manufacturing of composite structure <NUM>. The curing of composite structure <NUM> may be performed by applying at least one of heat, pressure, or a chemical reaction.

Resin <NUM> may comprise at least one of a thermoplastic material, a thermoset material, or some other type of material. Depending on the implementation, resin <NUM> may be comprised of multiple components, such as, for example, without limitation, at least one of a diluent, a catalyst, a monomer, an oligomer, a curative, particles, milled fibers, some other type of soluble or insoluble additive, or some other type of component.

The combination of discontinuous filaments <NUM> comprised of both stiffening material <NUM> and binding material <NUM>, as well as fiber matrix <NUM> being substantially isotropic <NUM>, may help strengthen filler <NUM> and make filler <NUM> resistant to undesired inconsistencies, such as cracking. For example, without limitation, filler <NUM> may be resistant to the cracking of resin <NUM> during curing, thermal cycling, or mechanical cycling.

In some illustrative examples, additional binder <NUM> may be added to fiber matrix <NUM> prior to resin <NUM>. Additional binder <NUM> may be, for example, without limitation, injected into fiber matrix <NUM> or applied directly to discontinuous filaments <NUM> prior to the forming of the three-dimensional fiber matrix <NUM>. Additional binder <NUM> may comprise at least one of, for example, without limitation, an adhesive material, a glue, a thermoplastic material, a polyetherimide, a thermoset material, or some other type of binding agent.

In one illustrative example, composite manufacturing system <NUM> may be used to manufacture composite structure <NUM>. Filler manufacturing system <NUM> may be part of composite manufacturing system <NUM>. In particular, filler manufacturing system <NUM> may be the portion of composite manufacturing system <NUM> used to manufacture filler <NUM>. Filler <NUM> may be manufactured in different ways using filler manufacturing system <NUM>. Composite manufacturing system <NUM> is described in greater detail in <FIG> below.

With reference now to <FIG>, an illustration of composite manufacturing system <NUM> from <FIG> is depicted in greater detail in the form of a block diagram in accordance with an illustrative aspect. Composite manufacturing system <NUM> may be used to manufacture filler <NUM> using first plurality of discontinuous filaments <NUM> and second plurality of discontinuous filaments <NUM>. In one illustrative example, composite manufacturing system <NUM> may include mixing system <NUM>, feedstock forming system <NUM>, and shaping system <NUM>.

Mixing system <NUM> may be used to mix first plurality of discontinuous filaments <NUM> and second plurality of discontinuous filaments <NUM> together to form mixture <NUM>. Mixing system <NUM> may mix first plurality of discontinuous filaments <NUM> and second plurality of discontinuous filaments <NUM> such that mixture <NUM> is a substantially homogenous mixture <NUM> comprised of randomly oriented discontinuous filaments <NUM>.

Feedstock forming system <NUM> may use mixture <NUM> to form feedstock <NUM>. Feedstock forming system <NUM> may be implemented in different ways. In one illustrative example, feedstock forming system <NUM> may include press device <NUM>, cutter <NUM>, blender <NUM>, and compressing device <NUM>.

Press device <NUM> may form sheet <NUM> using mixture <NUM>. For example, without limitation, press device <NUM> may apply pressure to mixture <NUM> to flatten mixture <NUM> out to form sheet <NUM>. Sheet <NUM> may be a thin veil of randomly oriented discontinuous filaments <NUM>.

Cutter <NUM> may be used to cut sheet <NUM> into plurality of strips <NUM>. In one illustrative example, the strips in plurality of strips <NUM> may have substantially uniform shapes and sizes. However, in other illustrative examples, plurality of strips <NUM> may be of different shapes, different sizes, or both.

Blender <NUM> may be used to mix plurality of strips <NUM> together to form feedstock material <NUM>. As one illustrative example, blender <NUM> may mix plurality of strips <NUM> at a high speed such that a wad of feedstock material <NUM> is formed. Feedstock material <NUM> may be substantially isotropic.

Compressing device <NUM> may then be used to compress feedstock material <NUM> to form the final feedstock <NUM>. For example, without limitation, compressing device <NUM> may compress feedstock material <NUM> with respect to three dimensions <NUM> at substantially constant rate <NUM> to form feedstock <NUM>. In particular, feedstock material <NUM> may be compressed with respect to three dimensions <NUM> at substantially constant rate <NUM> to form feedstock <NUM> having selected fiber volume fraction <NUM>. In one illustrative example, compression of feedstock material <NUM> may be performed isotatically, which may mean that equal pressure is applied to all sides of feedstock material <NUM>.

Selected fiber volume fraction <NUM> may be, for example, without limitation, between about <NUM> percent and <NUM> percent. In some cases, selected fiber volume fraction <NUM> may be preferably between about <NUM> percent and about <NUM> percent.

Once feedstock <NUM> has been fully formed, shaping system <NUM> may be used to form filler structure <NUM> using feedstock <NUM>. In one illustrative example, shaping system <NUM> includes cutting device <NUM>. Cutting device <NUM> may be used to cut out selected portion <NUM> of feedstock <NUM>.

For example, without limitation, cutting device <NUM> may be used to cut away a portion of feedstock <NUM> such that only selected portion <NUM> having selected shape <NUM> remains. Selected shape <NUM> may be a three-dimensional shape such as, for example, without limitation, a triangular-type prism, a hexagonal-type prism, a cylindrical shape, some other type of polyhedral shape, or some other type of three-dimensional shape.

In some illustrative examples, selected portion <NUM> of feedstock <NUM> having selected shape <NUM> forms filler structure <NUM>. However, in other illustrative examples, number of edges <NUM> of selected portion <NUM> of feedstock <NUM> may need to be further shaped in order to form filler structure <NUM>. Number of edges <NUM> may be shaped using, for example, edge shaping system <NUM>.

In one illustrative example, edge shaping system <NUM> may include number of rollers <NUM>. Number of rollers <NUM> may be rolled along number of edges <NUM> to shape number of edges <NUM>. Number of rollers <NUM> may include at least one of spherical roller <NUM>, cylindrical roller <NUM>, or some other type of roller. As one illustrative example, number of rollers <NUM> may be rolled along number of edges <NUM>, while heat <NUM> is being applied to number of edges <NUM> by heating device <NUM>, to shape number of edges <NUM>.

In another illustrative example, edge shaping system <NUM> may include mold <NUM>. Mold <NUM> may be comprised of one or more mold pieces. Selected portion <NUM> of feedstock <NUM> may be placed into mold <NUM>, which may shape number of edges <NUM>. For example, mold <NUM> may be shaped such that forcing selected portion <NUM> of feedstock <NUM> into mold <NUM> shapes number of edges <NUM>. Applying heat <NUM> to selected portion <NUM> of feedstock <NUM>, while selected portion <NUM> is in mold <NUM>, may set the shape of each of number of edges <NUM>.

In this manner, filler structure <NUM> may be formed in a number of different ways. Once filler structure <NUM> has been formed, in some illustrative examples, additional binder <NUM> may be injected within filler structure <NUM>. In other illustrative examples, additional binder <NUM> may be added to blender <NUM> prior to the mixing of plurality of strips <NUM> to form feedstock material <NUM>.

Resin <NUM> may then be impregnated within filler structure <NUM> to form filler <NUM>. As described in <FIG>, filler <NUM> may be formed such that filler <NUM> has set of filler properties <NUM> that substantially match set of properties <NUM> of composite structure <NUM>. Further, filler <NUM> is formed to reduce or prevent the development of undesired inconsistencies within filler <NUM>.

In other illustrative examples, resin <NUM> may be impregnated into selected portion <NUM> of feedstock <NUM> prior to the shaping of number of edges <NUM>. In this manner, filler structure <NUM> may or may not include resin <NUM>.

In this manner, composite manufacturing system <NUM> may be used to manufacture composite structure <NUM> having filler <NUM> that fills void <NUM>. Discontinuous filaments <NUM> may be used to form filler <NUM> having connectivity propagating in all directions with respect to three dimensions. Three-dimensional fiber matrix <NUM> comprised of discontinuous filaments <NUM> may be a three-dimensional network of filaments that may reduce the total amount of fiber required to support filler <NUM>. This reduced amount of fiber may, in turn, reduce the presence of micro-cracking and enable quicker manufacturing processes. For example, it may be easier to fill void <NUM> between first composite part <NUM> and second composite part <NUM>, which may be dry preforms, with filler <NUM> having a lower fiber density.

Additionally, three-dimensional fiber matrix <NUM> may increase the strength of and reduce the weight of filler <NUM>. Further, filler coefficient of thermal expansion <NUM> may be reduced and filler coefficient of thermal expansion <NUM> may be equally present in all directions with respect to three dimensions.

Filler <NUM> may be uniform in all directions. Consequently, filler <NUM> may be capable of carrying loads in all directions as needed.

The illustrations of manufacturing environment <NUM> in <FIG> and filler <NUM> and composite manufacturing system <NUM> in <FIG> are not meant to imply physical or architectural limitations to the manner in which an illustrative aspect may be implemented. Other components in addition to or in place of the ones illustrated may be used. Some components may be optional. 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 aspect.

With reference now to <FIG>, an illustration of an isometric view of a composite structure is depicted in accordance with an illustrative aspect. In this illustrative example, composite structure <NUM> may be an example of one implementation for composite structure <NUM> in <FIG>.

As depicted, composite structure <NUM> may include base <NUM>, part <NUM>, and part <NUM>. Void <NUM> is created between base <NUM>, part <NUM>, and part <NUM>. Void <NUM> may be an example of one implementation for void <NUM> in <FIG>. In this illustrative example, filler <NUM> is used to substantially fill void <NUM>. Filler <NUM> may be an example of one implementation for filler <NUM> in <FIG>. Filler <NUM> may be comprised of fiber matrix <NUM>. Fiber matrix <NUM> may be comprised of discontinuous filaments <NUM> that are randomly oriented and entangled with each other such that fiber matrix <NUM>, and thereby filler <NUM>, is substantially isotropic. Fiber matrix <NUM> and discontinuous filaments <NUM> may be examples of implementations for fiber matrix <NUM> and discontinuous filaments <NUM>, respectively, in <FIG>.

With reference now to <FIG>, an illustration of an enlarged view of a portion of a fiber matrix is depicted in accordance with an illustrative aspect. Fiber matrix <NUM> may be an example of one implementation for fiber matrix <NUM> in <FIG>. As depicted, fiber matrix <NUM> may include discontinuous filaments <NUM>, which may be an example of one implementation for discontinuous filaments <NUM> in <FIG>.

Discontinuous filaments <NUM> may include first plurality of discontinuous filaments <NUM> and second plurality of discontinuous filaments <NUM>. First plurality of discontinuous filaments <NUM> and second plurality of discontinuous filaments <NUM> may be examples of implementations for first plurality of discontinuous filaments <NUM> and second plurality of discontinuous filaments <NUM>, respectively, in <FIG>.

With reference now to <FIG>, an illustration of a feedstock and different types of fillers that may be made from the feedstock is depicted in accordance with an illustrative aspect. In this illustrative example, feedstock <NUM> may be an example of one implementation for feedstock <NUM> in <FIG>. Feedstock <NUM> may be substantially isotropic and comprised of randomly oriented discontinuous filaments <NUM>.

In one illustrative example, filler <NUM> having selected shape <NUM> may be formed by cutting out a selected portion from feedstock <NUM> and impregnating this selected portion with resin. As depicted, filler <NUM> may be used for filling a void within composite structure <NUM>.

As another illustrative example, filler <NUM> having selected shape <NUM> may be formed from feedstock <NUM> for use in filling a void within composite structure <NUM>. In yet another illustrative example, filler <NUM> having selected shape <NUM> may be formed from feedstock <NUM> for use in filling a void within composite structure <NUM>. Further, filler <NUM> having selected shape <NUM> may be formed from feedstock <NUM> for use in filling a void within composite structure <NUM>. Filler <NUM>, filler <NUM>, filler <NUM>, and filler <NUM> may each be an example of one implementation for filler <NUM> in <FIG>.

With reference now to <FIG>, an illustration of one manner in which a filler may be formed is depicted in accordance with an illustrative aspect. In this illustrative example, feedstock <NUM> may be an example of one implementation for feedstock <NUM> in <FIG>.

Selected portion <NUM> may be cut out from feedstock <NUM> using a cutting device such as, for example, without limitation, cutting device <NUM> in <FIG>. Selected portion <NUM> may be an example of one implementation for selected portion <NUM> in <FIG>.

As depicted, selected portion <NUM> may include edge <NUM>, edge <NUM>, and edge <NUM>. Resin (not shown) may then be impregnated within selected portion <NUM>.

Selected portion <NUM> may be pressed into cavity <NUM> of mold <NUM> by applying force <NUM> to edge <NUM> of selected portion <NUM>. Cavity <NUM> may be shaped such that forcing selected portion <NUM> into cavity <NUM> shapes edge <NUM> and edge <NUM>. Force <NUM> applied to edge <NUM> may also shape edge <NUM>.

Mold <NUM> may include plate <NUM> that is placed over edge <NUM> to maintain the desired shape for edge <NUM>. Heat <NUM> may then be applied to selected portion <NUM> within mold <NUM>. Heat <NUM> may cure selected portion <NUM> with resin (not shown) infused within selected portion <NUM> to form filler <NUM>. Filler <NUM> may have final shape <NUM>.

With reference now to <FIG>, an illustration of one manner in which a selected portion of feedstock may be formed is depicted in accordance with an illustrative aspect. In this illustrative example, feedstock <NUM> may be an example of one implementation for feedstock <NUM> in <FIG>. Electronic knife <NUM> may be used to cut out selected portion <NUM> having selected shape <NUM> from feedstock <NUM>. Electronic knife <NUM> may be an example of one implementation for cutting device <NUM> in <FIG>.

With reference now to <FIG>, an illustration of rollers being used to shape the edges of a selected portion of feedstock is depicted in accordance with an illustrative aspect. In this illustrative example, selected portion <NUM> may be an example of one implementation for selected portion <NUM> of feedstock <NUM> in <FIG>.

Rollers <NUM> may be an example of one implementation for number of rollers <NUM> in <FIG>. Rollers <NUM> include spherical roller <NUM>, spherical roller <NUM>, and spherical roller <NUM>. In one illustrative example, rollers <NUM> may be part of a nip roll compression system. Spherical roller <NUM> may be rotated about axis <NUM> in the direction of arrow <NUM> to shape edge <NUM> of selected portion <NUM> such that edge <NUM> substantially conforms to the radius of curvature of spherical roller <NUM>.

Similarly, spherical roller <NUM> may be rotated about axis <NUM> in the direction of arrow <NUM> to shape edge <NUM> of selected portion <NUM> such that edge <NUM> substantially conforms to the radius of curvature of spherical roller <NUM>. Further, spherical roller <NUM> may be rotated about axis <NUM> in the direction of arrow <NUM> to shape edge <NUM> of selected portion <NUM> such that edge <NUM> substantially conforms to the radius of curvature of spherical roller <NUM>.

Rollers <NUM> may be an example of one implementation for number of rollers <NUM> in <FIG>. In one illustrative example, rollers <NUM> may be part of a nip roll compression system. Rollers <NUM> include cylindrical roller <NUM>, spherical roller <NUM>, and spherical roller <NUM>. Cylindrical roller <NUM> may be rotated about axis <NUM> in the direction of arrow <NUM> to shape edge <NUM> of selected portion <NUM> such that edge <NUM> substantially conforms to the radius of curvature of cylindrical roller <NUM>.

Further, spherical roller <NUM> may be rotated about axis <NUM> in the direction of arrow <NUM> to shape edge <NUM> of selected portion <NUM> such that edge <NUM> substantially conforms to the radius of curvature of spherical roller <NUM>. Spherical roller <NUM> may be rotated about axis <NUM> in the direction of arrow <NUM> to shape edge <NUM> of selected portion <NUM> such that edge <NUM> substantially conforms to the radius of curvature of spherical roller <NUM>.

Rollers <NUM> may be an example of one implementation for number of rollers <NUM> in <FIG>. In one illustrative example, rollers <NUM> may be part of a nip roll compression system. Rollers <NUM> include spherical roller <NUM>, spherical roller <NUM>, spherical roller <NUM>, and spherical roller <NUM>. Spherical roller <NUM>, spherical roller <NUM>, spherical roller <NUM>, and spherical roller <NUM> may be used to shape edge <NUM>, edge <NUM>, edge <NUM>, and edge <NUM>, respectively, of selected portion <NUM>.

The illustrations in <FIG> are not meant to imply physical or architectural limitations to the manner in which an illustrative aspect may be implemented. Other components in addition to or in place of the ones illustrated may be used. Some components may be optional.

The different components shown in <FIG> may be illustrative examples of how components shown in block form in <FIG> can be implemented as physical structures. Additionally, some of the components in <FIG> may be combined with components in <FIG>, used with components in <FIG>, or a combination of the two.

With reference now to <FIG>, an illustration of a process for forming a filler for a void in a composite structure is depicted in the form of a flowchart in accordance with an illustrative aspect. The process illustrated in <FIG> may be used to form filler <NUM> in <FIG>. In one illustrative example, the process illustrated in <FIG> may be implemented using composite manufacturing system <NUM> in <FIG>.

The process may begin by mixing a first plurality of discontinuous filaments with a second plurality of discontinuous filaments to form a mixture (operation <NUM>). In one illustrative example, the mixture formed in operation <NUM> may be a homogenous mixture. The homogenous mixture may have a uniform composition and uniform properties. In particular, the first plurality of discontinuous filaments and the second plurality of discontinuous filaments may be substantially uniformly distributed throughout the mixture.

Next, feedstock material may be formed using the mixture (operation <NUM>). Thereafter, the feedstock material is compressed with respect to three dimensions to form a feedstock in which the first plurality of discontinuous filaments and the second plurality of discontinuous filaments within the feedstock are randomly oriented and entangled with each other to form a fiber matrix that is substantially isotropic (operation <NUM>).

The feedstock may be shaped to form a filler structure (operation <NUM>). Resin may then be infused within the fiber matrix of the filler structure to form a filler for substantially filling a void of a composite structure (operation <NUM>), with the process terminating thereafter.

In some illustrative examples, operation <NUM> is not performed. In these examples, the filler structure formed in operation <NUM> may form the final filler. This filler may be referred to as a dry filler. This dry filler may be collocated with a first dry preform and a second dry preform to form a composite structure. The dry filler may fill a void between the first dry preform and a second dry preform. Resin may then be infused into the composite structure to form a resin-infused composite structure, which may then be cured to form a fully cured and final composite structure.

With reference now to <FIG>, an illustration of a process for forming a feedstock is depicted in the form of a flowchart in accordance with an illustrative aspect. The process illustrated in <FIG> may be an example of one manner in which operation <NUM> and operation <NUM> in <FIG> may be performed. Further, this process may be implemented using, for example, without limitation, feedstock forming system <NUM> in <FIG>.

The process may begin by applying at least one of force or pressure to a mixture of discontinuous filaments to form a sheet of randomly oriented discontinuous filaments (operation <NUM>). In operation <NUM>, the mixture may be the mixture formed in operation <NUM> in <FIG>. This mixture may be a substantially homogenous mixture.

The sheet may then be cut into a plurality of strips (operation <NUM>). The plurality of strips may be recombined to form feedstock material (operation <NUM>). In one illustrative example, operation <NUM> may be performed using a blender to blend together the plurality of strips to form feedstock material.

The feedstock material may be compressed with respect to three dimensions at a substantially constant rate to form a feedstock having a selected fiber volume fraction (operation <NUM>), with the process terminating thereafter. In operation <NUM>, the selected fiber volume fraction may be, for example, without limitation, between about <NUM> percent and about <NUM> percent. In some cases, in operation <NUM>, the feedstock material may be compressed at a substantially constant rate in directions corresponding to the three dimensions.

With reference now to <FIG>, an illustration of a more detailed process for forming a filler for a void in a composite structure is depicted in the form of a flowchart in accordance with an illustrative aspect. The process illustrated in <FIG> may be used to form filler <NUM> in <FIG>. In one illustrative example, the process illustrated in <FIG> may be implemented using composite manufacturing system <NUM> in <FIG>.

The process may begin by mixing a first plurality of discontinuous filaments with a second plurality of discontinuous filaments to form a substantially homogenous mixture in which the filaments are randomly oriented (operation <NUM>). Next, the mixture may be used to form feedstock material (operation <NUM>).

The feedstock material may be compressed with respect to three dimensions to form a feedstock comprising a fiber matrix in which the first plurality of discontinuous filaments and the second plurality of discontinuous filaments are randomly oriented and entangled with each other such that the fiber matrix is substantially isotropic (operation <NUM>). The fiber matrix may be a three-dimensional fiber matrix.

A selected portion having a selected shape may then be cut out of the feedstock (operation <NUM>). A number of edges of the selected portion of the feedstock may be shaped using at least one of a cutting device, a number of spherical rollers, a number of cylindrical rollers, a mold, a heating device, or some other type of device to form a filler structure (operation <NUM>). Resin may be infused within the filler structure to form a filler for substantially filling a void of a composite structure (operation <NUM>), with the process terminating thereafter.

The flowcharts and block diagrams in the different depicted aspects illustrate the architecture, functionality, and operation of some possible implementations of apparatuses and methods in an illustrative aspect. 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.

In some alternative implementations of an illustrative aspect, the function or functions noted in the blocks may occur out of the order noted in the figures. For example, in some cases, two blocks shown in succession may be executed substantially concurrently, or the blocks may sometimes be performed in the reverse order, depending upon the functionality involved. Also, other blocks may be added in addition to the illustrated blocks in a flowchart or block diagram.

The illustrative aspects of the disclosure may be described in the context of aircraft manufacturing and service method <NUM> as shown in <FIG> and aircraft <NUM> as shown in <FIG>. Turning first to <FIG>, an illustration of an aircraft manufacturing and service method is depicted in the form of a block diagram in accordance with an illustrative aspect. During pre-production, aircraft manufacturing and service method <NUM> may include specification and design <NUM> of aircraft <NUM> in <FIG> and material procurement <NUM>.

During production, component and subassembly manufacturing <NUM> and system integration <NUM> of aircraft <NUM> in <FIG> takes place. Thereafter, aircraft <NUM> in <FIG> may go through certification and delivery <NUM> in order to be placed in service <NUM>. While in service <NUM> by a customer, aircraft <NUM> in <FIG> is scheduled for routine maintenance and service <NUM>, which may include modification, reconfiguration, refurbishment, and other maintenance or service.

With reference now to <FIG>, an illustration of an aircraft is depicted in the form of a block diagram in which an illustrative aspect may be implemented. In this example, aircraft <NUM> is produced by aircraft manufacturing and service method <NUM> in <FIG> and may include airframe <NUM> with plurality of systems <NUM> and interior <NUM>. Examples of systems <NUM> include one or more of propulsion system <NUM>, electrical system <NUM>, hydraulic system <NUM>, and environmental system <NUM>. Any number of other systems may be included. Although an aerospace example is shown, different illustrative aspects may be applied to other industries, such as the automotive industry.

The apparatuses and methods embodied herein may be employed during at least one of the stages of aircraft manufacturing and service method <NUM> in <FIG>. In particular, filler <NUM> from <FIG> may be manufactured and used during any one of the stages of aircraft manufacturing and service method <NUM>. For example, without limitation, filler <NUM> from <FIG> may be manufactured, used, or both during at least one of material procurement <NUM>, component and subassembly manufacturing <NUM>, system integration <NUM>, routine maintenance and service <NUM>, or some other stage of aircraft manufacturing and service method <NUM>. Still further, fillers, such as filler <NUM> from <FIG>, may be used to fill voids in composite structures that form airframe <NUM> or interior <NUM> of aircraft <NUM>.

In one illustrative example, components or subassemblies produced in component and subassembly manufacturing <NUM> in <FIG> may be fabricated or manufactured in a manner similar to components or subassemblies produced while aircraft <NUM> is in service <NUM> in <FIG>. As yet another example, one or more apparatus aspects, method aspects, or a combination thereof may be utilized during production stages, such as component and subassembly manufacturing <NUM> and system integration <NUM> in <FIG>. One or more apparatus aspects, method aspects, or a combination thereof may be utilized while aircraft <NUM> is in service <NUM> and/or during maintenance and service <NUM> in <FIG>. The use of a number of the different illustrative aspects may substantially expedite the assembly of and/or reduce the cost of aircraft <NUM>.

Thus, in summary, according to the examples of the present disclosure not encompassed by the wording of the claims:
It is disclosed a fiber matrix (<NUM>) comprising:.

Claim 1:
An apparatus comprising:
a composite structure (<NUM>, <NUM>) having a void (<NUM>, <NUM>); and
a filler (<NUM>, <NUM>) comprising a fiber matrix (<NUM>) that is uniform in all directions, wherein the fiber matrix (<NUM>) comprises:
a first plurality of discontinuous filaments (<NUM>) in which each filament (<NUM>) of the first plurality of discontinuous filaments (<NUM>) is comprised of a stiffening material (<NUM>); and
a second plurality of discontinuous filaments (<NUM>) in which each filament (<NUM>) of the second plurality of discontinuous filaments (<NUM>) is comprised of a binding material (<NUM>),
wherein discontinuous filaments (<NUM>) of both the first plurality of discontinuous filaments (<NUM>) and the second plurality of discontinuous filaments (<NUM>) are randomly oriented and entangled with each other,
wherein the filler (<NUM>, <NUM>) is used for substantially filling the void (<NUM>, <NUM>) and wherein the filler (<NUM>, <NUM>) has a set of filler properties (<NUM>) that substantially match a set of properties (<NUM>) of the composite structure (<NUM>, <NUM>), wherein, the set of filler properties (<NUM>) includes a coefficient of thermal expansion (<NUM>) and stiffness (<NUM>).