CONFORMABLE TOOLING SYSTEMS AND METHODS FOR COMPLEX CONTOUR COMPOSITE PREFORMS

A preform tooling arrangement includes a base plate comprising a male die surface and a stripper plate comprising a female die surface. A plurality of perforations are disposed in the base plate and/or the stripper plate. The stripper plate is moveable with respect to the base plate. The preform tooling arrangement is configured to receive a fibrous preform between the male die surface and the female die surface. The preform tooling arrangement is a dual-purpose fixture configured to accommodate z-needling and densification, all while the fibrous preform remains in the same fixture (i.e., the preform tooling arrangement). The perforations are configured to receive one or more textile needles for through thickness reinforcement of the fibrous preform.

FIELD

The present disclosure relates to systems and methods for manufacturing composites.

BACKGROUND

Composite bodies are utilized in various industries, including the aerospace industry. Typically, one or more layers of a composite material are stacked together over a mold. The layers may be needled with textile needling to generate a series of z-fibers that extend in the through-thickness direction of the stacked layers. In the case of C/C (carbon/carbon) composites, the shaped preform is then typically moved to one or more other fixtures as it goes through heat treatment and densification processes.

SUMMARY

According to various embodiments, a preform tooling arrangement is disclosed, comprising a base plate comprising a male die surface, a stripper plate comprising a female die surface, a first plurality of perforations disposed in the base plate, and a second plurality of perforations disposed in the stripper plate. The stripper plate is moveable with respect to the base plate, and the preform tooling arrangement is configured to receive a fibrous preform between the male die surface and the female die surface. Each perforation of the first plurality of perforations can be configured to receive a textile needle. Each perforation of the second plurality of perforations can be configured to receive a textile needle.

In various embodiments, the base plate comprises two or more base plate sub-components that are configured together to define the male die surface. In various embodiments, the stripper plate comprises two or more stripper plate sub-components that are configured together to define the female die surface.

In various embodiments, the first plurality of perforations extend from the male die surface to a recess surface in the base plate. In various embodiments, the second plurality of perforations extend from the female die surface to an outer surface in the stripper plate. In various embodiments, each of the second plurality of perforations are sized and configured to receive a textile needle. In various embodiments, each of the first plurality of perforations are sized and configured to receive the textile needle.

In various embodiments, each of the second plurality of perforations are sized and configured to receive the textile needle. Each of the first plurality of perforations can be sized and configured to receive the textile needle. A center axis of each perforation of the first plurality of perforations can be aligned with a center axis of a corresponding perforation of the second plurality of perforations. Each perforation of the second plurality of perforations disposed in the stripper plate can be configured to receive the textile needle therethrough, whereby the textile needle penetrates through said perforation, through the fibrous preform, and at least partially through the corresponding perforation of the first plurality of perforations disposed in the base plate.

In various embodiments, the male die surface is a convex surface and the female die surface is a concave surface.

In various embodiments, the base plate comprises a metallic material, a graphite material, a C/C composite material, and/or a ceramic matrix composite material, e.g., SiC/SiC material among others. In various embodiments, the stripper plate comprises a metallic material, a graphite material, a C/C composite material, and/or a ceramic matrix composite material, e.g., SiC/SiC material among others.

In various embodiments, the plurality of perforations in the base plate and stripper plate are configured to generate a plurality of perforation zones with different perforation densities, or number of perforations per unit area, and patterns, e.g., a rectangular pattern, a hexagonal pattern, a triangular pattern, a circular pattern, among others. In various embodiments, when the stripper plate is positioned over the base plate, the plurality of perforations in the stripper plate are configured to align with the plurality of perforations in the base plate.

In various embodiments, the plurality of perforations in the base plate and the stripper plate are configured to create a first zone with a first perforation density, and a second zone with a second perforation density, where the first perforation density is higher than the second perforation density.

In various embodiments, the plurality of perforations in the base plate and in the stripper plate are configured to create alternating regions of needled and non-needled regions along a direction in the fibrous preform placed between the base plate and the stripper plate.

In various embodiments, at least one of the first plurality of perforations or the second plurality of perforations comprises a first zone with a first perforation density, and a second zone with a second perforation density, wherein the first perforation density is higher than the second perforation density, and wherein the perforations in the first zone and the second zone are configured to receive the textile needle.

In various embodiments, the first plurality of perforations and the second plurality of perforations comprise perforated zones alternating with non-perforated zones.

In various embodiments, at least one of the first plurality of perforations or the second plurality of perforations are arranged in a pattern, and wherein the pattern comprises at least one of a rectangular pattern, a hexagonal pattern, a triangular pattern, or a circular pattern.

According to various embodiments, a method for manufacturing a needled fibrous composite preform part is disclosed. The method comprises positioning a plurality of layers of a fibrous preform over a base plate, positioning a stripper plate to conform to the base plate and over the plurality of layers, compressing the plurality of layers between the base plate and the stripper plate, disposing a textile needle through a first perforation disposed in the stripper plate and at least partially into the plurality of layers, to form a needled fibrous preform.

In various embodiments, a method for through thickness needling of a fibrous preform is disclosed and comprises positioning a plurality of layers of a fibrous preform between the base plate and the stripper plate, compressing the plurality of layers between the base plate and the stripper plate, disposing a textile needle through a first perforation disposed in the stripper plate, into the plurality of layers, and at least partially into a corresponding perforation disposed in the base plate to perform a through thickness needling of the fibrous preform.

According to various embodiments, a method for manufacturing a composite part is disclosed. The method comprises positioning a base plate comprising a first plurality of perforations, positioning a first plurality of layers of a fibrous preform over the base plate, positioning a stripper plate comprising a second plurality of perforations over the first plurality of layers, compressing the first plurality of layers between the base plate and the stripper plate, and providing through-thickness reinforcement in the fibrous preform by disposing a textile needle through at least one perforation of at least one of the first plurality of perforations or the second plurality of perforations and at least partially into the fibrous preform.

In various embodiments, the method further comprises moving an expanding joint of the stripper plate to a contracted position to conform to the first plurality of layers, disposing the textile needle through a first perforation disposed in the stripper plate and at least partially into the first plurality of layers, removing the stripper plate from the first plurality of layers, positioning a second plurality of layers of the fibrous preform over the first plurality of layers, positioning the stripper plate over the second plurality of layers, and moving the expanding joint of the stripper plate to an expanded position to conform to the second plurality of layers.

In various embodiments, the method further comprises increasing a thickness of the fibrous preform in response to positioning the second plurality of layers over the first plurality of layers. In various embodiments, the method further comprises disposing the textile needle through the first perforation disposed in the stripper plate, through the second plurality of layers, and at least partially into the first plurality of layers.

In various embodiments, the expanding joint comprises at least one of a tongue and groove joint, interlocking teeth, or a dovetail.

In various embodiments, the method further comprises contracting the expanding joint in response to compressing the fibrous preform.

According to various embodiments, a method for manufacturing a composite preform part, comprising a plurality of layers, is disclosed. The method comprises positioning a fibrous preform with a preform tooling arrangement comprising a base plate and a stripper plate, compressing the fibrous preform between the base plate and the stripper plate, disposing a textile needle through at least one perforation of a plurality of perforations disposed in the stripper plate (or the base plate) and at least partially into the fibrous preform, moving the fibrous preform into a furnace while the fibrous preform remains in the preform tooling arrangement, heating the fibrous preform to a densification temperature while the fibrous preform remains in the preform tooling arrangement, and flowing gases through the perforations and into the fibrous preform to densify the fibrous preform via chemical vapor infiltration.

In various embodiments, the gases are hydrocarbon gases. It should be understood, however, that the same tooling arrangement may be used to flow other reactant gases to deposit other matrices to produce other composite materials—for example methyltrichlorosilane (MTS) or CH3Cl3Si for silicon carbide, BCl3and NH3for BN, SiCl4and hydrocarbon for silicon carbide, SiCl4and ammonia for silicon nitride, BCl3and hydrocarbon for B4C, and the like including combinations thereof In addition, inert, diluting, and/or inhibiting gases such as argon, hydrogen and HCl may be combined with the forementioned reactant gases to control deposition rates and morphology of the deposited compounds.

In various embodiments, the method further comprises securing the entire assembly, such that the fibrous preform, the base plate, and the stripper plate remain substantially in the same position relative to one another.

In various embodiments, the gases comprise of hydrocarbons and the densification temperature is in a range from 650° C. to 1425° C. In various embodiments, the densification temperature is in a range from 815° C. to 1040° C.

In various embodiments, the method further comprises flowing the gases through a second perforation disposed in the base plate and into the fibrous preform to deposit carbon from the gases on and within the fibrous preform. In various embodiments the method further comprises aligning the perforations in the base plate and the stripper plate with the needled regions of the fibrous preform to create paths for gases to flow through the fibrous preform.

In various embodiments, the method further comprises heating the fibrous preform to a (carbonization and/or heat-treatment) temperature greater than about 1,000 degrees Celsius.

In various embodiments, the textile needle comprises at least one of a tufting needle or a stitching needle configured to dispose a through thickness reinforcement fibrous filament at least partially through a plurality of layers of the fibrous preform.

In various embodiments, the fibrous filament for through thickness reinforcement comprises at least one of a fiber already disposed in at least one layer of the plurality of layers of the fibrous preform, a carbon fiber, or an oxidized PAN fiber.

In various embodiments, the fibrous filament for through-thickness reinforcement further comprises a fugitive fiber, and the method further comprises heating the reinforced fibrous preform while the fibrous preform remains in the tooling preform arrangement to allow the fugitive fiber to burn away and create channels in the through-thickness direction, and densifying the composite by chemical vapor infiltration by flowing gases through the perforations and into the fibrous preform via the channels in the through thickness direction created by the burning away of fugitive fibers.

In various embodiments, the method further comprises placing a foam layer proximate to the base plate or the stripper plate during the preform needling process. In various embodiments, the method further comprises burning away the foam layer during a chemical vapor infiltration and/or a heat-treatment process.

In various embodiments, the method further comprises biasing the base plate toward the stripper plate with a clamp comprising a first clamp half moveable with respect to a second clamp half, wherein the first clamp half is configured to move toward the second clamp half while the fibrous preform is in the furnace.

DETAILED DESCRIPTION

All ranges and ratio limits disclosed herein may be combined. It is to be understood that unless specifically stated otherwise, references to “a,” “an,” and/or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural.

As used herein, “fiber volume ratio” means the ratio of the volume of the fibers of the fibrous preform to the total volume of the fibrous preform. For example, a fiber volume ratio of 25% means the volume of the fibers in the fibrous preform is 25% of the total volume of fibrous preform.

As used herein, the term “fiber density” is used with its common technical meaning with units of g/cm3or g/cc. The fiber density may refer specifically to that of the individual fibers in the fibrous preform. The density will be measured, unless otherwise noted, by taking the weight divided by the geometric volume of each fiber. The density may refer to an average density of a plurality of fibers included in a fibrous preform.

As used herein, “CVI/CVD” may refer to chemical vapor infiltration and/or chemical vapor deposition. Accordingly, CVI/CVD may refer to chemical vapor infiltration or deposition or both.

As used herein, the term “through thickness reinforcement” includes “needling,” “stitching,” and/or “tufting,” in accordance with various embodiments.

As used herein, the term “needling” includes traditional needling, “stitching,” and/or “tufting,” in accordance with various embodiments.

As used herein, CVI/CVD is described herein, in connection with carbon/carbon composite materials as an example, using hydrocarbon gases as the source of carbon. It should be understood, however, that the tooling arrangement of the present disclosure may be used to flow other reactant gases to deposit carbon and other matrices to produce a variety of composite materials—for example, methyltrichlorosilane may be used to infiltrate the composite with a silicon carbide matrix, BCl3and ammonia may be used to deposit BN, SiCl4and hydrocarbon may be used for silicon carbide, SiCl4and ammonia for silicon nitride, or combinations thereof In addition, inert gases, diluting gases, and/or inhibiting gases such as argon, hydrogen, and HCl may be combined with these gases to control deposition rates and the morphology of the deposited material.

In various embodiments, the subject matter of this disclosure is generally directed toward fibrous preforms that do not shrink (e.g., carbon fiber); though system and methods of the present disclosure can be utilized with for fibers that exhibit shrinkage, such as OPF, without departing from the scope of the present disclosure.

In general, there are several methods of manufacturing carbon/carbon (“C/C”) materials depending on the part geometries and the end application performance requirements. One method involves starting with a dry fibrous preform, forming the preform into a shape by laying up on a tool, fixturing the formed shape into suitable graphite fixtures designed to maintain the formed shape but with perforations for allowing gases to flow, and depositing carbon matrix on the fibers by chemical vapor infiltration (CVI) using suitable reactant gases, pressures, and temperatures to fill the voids between the fibers and densify the part. The chemical vapor infiltration cycles may continue, in conjunction with intermediate machining of the surfaces of the preform between infiltration cycles if desired, until the desired part density is achieved. A second method involves the layup and cure of a fabric comprising of carbon fiber and pre-impregnated with a polymer resin. Process steps for forming a shaped part include the steps of laying-up of several layers of the pre-impregnated fabric onto a tool to form a preform, cure of the fiber-reinforced resin preform to form a rigid shape, pyrolysis of the cured shape to decompose or pyrolyze the resin leaving behind carbon fiber and a matrix comprising of carbon or substantially carbon (>85% by weight of the pyrolyzed resin). In this method, additional polymer resin infiltration and pyrolysis cycles may be employed to increase the amount of carbon matrix in the composites, or until the part achieves the desired density. Other methods, including variations and combinations of the above process methods are also in use and may include variations in preform architecture, infiltration resin type, and chemical vapor infiltration conditions. The subject matter of the present disclosure is particularly suited for methods starting with dry fibrous preforms and employing chemical vapor infiltration, but benefits may be realized for the other methods.

In the foregoing, the fibrous preform comprises a plurality of fabric layers. In various embodiments, the fabric layers comprise a plurality of continuous fiber tows, wherein a fiber tow comprises of a plurality of fiber filaments. These fabric layers may be a weave (e.g., a plain weave, a five harness satin weave, an eight harness satin weave, a basket weave, among others), a braid (e.g., a biaxial braid, a triaxial braid, and the like), and/or a unidirectional tape or fabric layer. The fabric layers may also comprise one or more unidirectional tape or fabric layers wherein each layer is oriented in a different direction relative to the other layer and stitched together to form a stitched non-crimp fabric, as is known in the art. The fibrous preform may further comprise of a fabric layer with discontinuous fibers (e.g., a non-woven fiber mat or veil comprising of discontinuous fibers, chopped fibers and the like). These discontinuous fibers may be randomly oriented or preferentially aligned predominantly in one direction.

The fibrous preform may be shape formed into a net shape, or near net shape, of the final composite part by laying up in a tool fixture or a closed mold, or the like. Before, during, or immediately after (i.e., before any subsequent processing such as consolidation, densification, and/or densification) being shape formed, the fibrous preform may undergo a through thickness reinforcement process (e.g., Z-needling, tufting, and/or stitching).

After a fibrous preform is formed into the shape and undergoes a through-thickness reinforcement, the preform is densified. In general, densification involves filling the voids, or pores, of the fibrous preform with additional carbon material. Typically, chemical vapor infiltration and deposition (“CVI/CVD”) techniques are used to densify the porous fibrous preform with a carbon matrix. This commonly involves heating the furnace and the carbon preforms, and flowing hydrocarbon gases into the furnace and around and through the fibrous preforms. As a result, carbon from the hydrocarbon gases separates from the gases and is deposited on and within the fibrous preforms. When the densification step is completed, the resulting C/C part has a carbon fiber structure with a carbon matrix infiltrating the fiber structure, thereby deriving the name “carbon/carbon.” In some cases, the fibrous preform may be heat-treated prior to densification and/or after densification. The heat-treatment is intended to stabilize or otherwise modify the microstructure of the fiber and/or the matrix, the bonding between the fiber and matrix, drive out any volatiles or undesirable impurities from the composite, or combinations, thereof. These steps of preforming, through-thickness reinforcement, shape-forming, densification and heat-treatment typically involve moving the fibrous preform between various tools for the different manufacturing steps, which can be cumbersome and time consuming.

C/C parts of the present disclosure may be particularly useful for high temperature aerospace applications. C/C parts of the present disclosure may be especially useful in these applications because of the superior high temperature characteristics of C/C material. In particular, the carbon/carbon material used in C/C parts is a good conductor of heat and is able to dissipate heat generated during high temperature conditions. Carbon/carbon material is also highly resistant to heat damage, and thus, may be capable of sustaining forces during severe conditions without mechanical failure.

FIG.1is a perspective illustration, in accordance with various embodiments, of a preform tooling arrangement100(also referred to herein as a conformable preform tooling arrangement). Tooling arrangement100includes a base plate110and a stripper plate120. Base plate110may define a male die surface112for receiving a fibrous preform102. Male die surface112may be a convex surface. Stripper plate120may define a female die surface122for receiving fibrous preform102. Female die surface122may be a concave surface. In this manner, fibrous preform102may conform to a size and geometry of the male die surface112and female die surface122.FIG.1illustrates fibrous preform102installed between male die surface112and female die surface122. Base plate110and stripper plate120may be made from a metallic material, a graphite material, a C/C composite material, and/or a ceramic matrix composite material, e.g., SiC/SiC material among others.

During a near net shape lay-up process, one or more sheets or layers of material (e.g., carbon fiber in various embodiments) may be laid up over base plate110to form fibrous preform102. Stripper plate120may be placed over base plate110to compress the fibrous preform102therebetween.

FIG.2illustrates, in accordance with various embodiments, the tooling arrangement100during a needling process. Fibrous preform102may undergo a needling process after, or during, the near net shape lay-up process while fibrous preform102remains in the same fixture (i.e., between base plate110and stripper plate120). Stated differently, tooling arrangement100may accommodate both near net shape lay-up and needling processes. In this regard, base plate110comprises a plurality of perforations114(also referred to herein as a first plurality of perforations). Stripper plate120similarly comprises a plurality of perforations124(also referred to herein as a second plurality of perforations). Perforations114and perforations124may be configured to align such that the center axis of each perforation114aligns with the center axis of a corresponding perforation124; though in various embodiments perforations114do not align with perforations124. In this manner, perforations114and perforations124may align such that each perforation can receive a needle150therethrough during the needling process. In this regard, perforations114and/or perforations124may be sized to receive a textile needle150.

In various embodiments, the plurality of perforations in the base plate110and stripper plate120are configured to generate a plurality of perforation zones with different perforation densities, or number of perforations per unit area. For example, momentary reference toFIG.14, perforations114and/or perforations124may generate a first zone A comprising a first density, a second zone B comprising a second density different from that of zone A, and/or a third zone C comprising a third density different from that of zone A and zone B. In various embodiments, perforation density can be greater in some areas to allow for increased needle density (through-thickness reinforcement) in order to increase the interlaminar strength of fibrous preform so as to handle an expected increased interlaminar stress on the final part.

In various embodiments, the plurality of perforations in the base plate110and stripper plate120are configured to generate a plurality of patterns, e.g., a rectangular pattern, a hexagonal pattern, a triangular pattern, a circular pattern, among others. For example, with momentary reference toFIG.15AthroughFIG.15D, needling penetration patterns may be selected from various shapes at various locations of the fibrous preform, for example depending on the desired through thickness reinforcement and the expected interlaminar stress.FIG.15AthroughFIG.15Dillustrate plates410(i.e., base plate110and/or stripper plate120) with apertures440(each representing a single needle punch). Needling penetrations patterns (i.e., the arrangement of apertures440) can comprise a triangular pattern (seeFIG.15A), a square pattern (seeFIG.15B), a hexagonal pattern (seeFIG.15C), and/or a curvilinear pattern (seeFIG.15D).

With reference toFIG.16AthroughFIG.16F, needling penetration zones may be selected from various shapes at various locations of the fibrous preform depending on the desired through thickness reinforcement and the expected interlaminar stress.FIG.16AthroughFIG.16Fillustrate plates510(i.e., base plate110and/or stripper plate120) with black areas442representing a non-perforated zone (e.g., a non-needled zone) and white areas444representing a perforated zone (e.g., a needled zone). In this regard, a first perforated zone may be spaced apart from a second perforated zone, wherein a non-perforated zone is disposed therebetween. Stated differently, perforations in the base plate110and/or the stripper plate120may form perforated zones alternating with non-perforated zones along the surface of the base plate110and/or the stripper plate120(e.g., along a direction perpendicular to a center axis of the perforations). Perforation zones (i.e., the areas where the fibrous preform is needled) can comprise a plurality of triangular patterns (seeFIG.16A), a plurality of square patterns (seeFIG.16B), a plurality of hexagonal-triangular patterns (seeFIG.16C), a plurality of curvilinear patterns (seeFIG.16D), a matrix of hexagonal patterns (seeFIG.16E), and/or a plurality of linear patterns (seeFIG.16F). In this regard, the plurality of perforations in the base plate110and the plurality of perforations in the stripper plate120may be configured to create alternating regions of needled and non-needled regions along a direction in the fibrous preform102placed between the base plate110and the stripper plate120, in accordance with various embodiments.

With reference toFIG.2, the layers of the fibrous preform102may be needled perpendicularly to each other (i.e., along the Z-direction) with barbed, textile needles or barbless, structuring needles. In various embodiments, the layers are needled at an angle of between 0° and 60° (e.g., 0°, 30°, 45°, and/or 60°) with respect to the Z-direction to each other. The needling process generates a series of z-fibers through fibrous preform102that extend perpendicularly to the fibrous layers. The z-fibers are generated through the action of the needles150pushing fibers from within the layer (x-y or in-plane) and reorienting them in the z-direction (through-thickness). Needling of the fibrous preform may be done as one or more layers are added to the stack or may be done after the entire stack of layers is formed. The needles150may also penetrate through only a portion of fibrous preform102, or may penetrate through the entire fibrous preform102. In addition, resins are sometimes added to fibrous preform102by either injecting the resin into the preform following construction or coating the fibers or layers prior to forming the fibrous preform102. The needling process may take into account needling parameters optimized to maintain fiber orientation, minimize in-plane fiber damage, and maintain target interlaminar properties. It should be understood that the Z-direction inFIG.2corresponds to the location of needles150. It should be understood however that the Z-direction is meant to correspond to the direction perpendicular to the plane of the fibrous preform102at the location the fibrous preform102is being needled. For example, the Z-direction at the sidewall104of the fibrous preform102would be the direction labeled as the X-direction inFIG.2. It should also be understood that the Z-direction may be at an angle to the plane of the fibrous preform102at the location the fibrous preform102is being needled, and the perforations in the base plate110and the stripper plate(s)120may be configured to receive the needle at such angle.

FIG.3illustrates, in accordance with various embodiments, a perspective view of the stripper plate120. Stripper plate120extends longitudinally along a longitudinal centerline190of the stripper plate120(e.g., along a Y-axis) between and to a first end130of the stripper plate120and a second end131of the stripper plate120. The stripper plate120extends laterally (e.g., along an X-axis) between and to a first side132of the stripper plate120and a second side133of the stripper plate120. The stripper plate120extends vertically (e.g., along a Z-axis) between and to a bottom side134of the stripper plate120and a top side135of the stripper plate120.

The stripper plate120is configured with at least one die recess136; e.g., an aperture such as a pocket, a channel, a groove, etc. The die recess136ofFIG.3extends (e.g., partially) vertically into the stripper plate120from one or more bottom surfaces137of the stripper plate120to female die surface122of the stripper plate120, where the bottom surfaces137ofFIG.3are arranged on opposing sides of the female die surface122at the bottom side134. The die recess136ofFIG.3extends longitudinally in (e.g., through) the stripper plate120, for example, between and to the stripper plate first end130and/or the stripper plate second end131. The die recess136ofFIG.3extends laterally in (e.g., within) the stripper plate120, for example, between opposing lateral sides of the female die surface122.

The female die surface122is a concave or concave-convex surface and may have a curved geometry; e.g., a three-dimensional (3D) curvature. The female die surface122ofFIG.3, for example, has a curved (e.g., arcuate, splined, etc.) cross-sectional geometry in a lateral-vertical reference plane; e.g., an X-Z plane. The female die surface122may also have a curved (e.g., arcuate, splined, etc.) cross-sectional geometry in a longitudinal-vertical reference plane; e.g., a Y-Z plane. This recess curvature may change as the female die surface122/the die recess136extends laterally and/or longitudinally, which may provide the female die surface122with a complex 3D curvature. In various embodiments, the recess curvature may remain uniform as the female die surface122/the die recess136extends laterally and/or longitudinally. The female die surface122may be configured without any sharp corners or sharp transitions.

Stripper plate120further comprises an outer surface138. In various embodiments, outer surface138generally follows the contour of female die surface122such that a wall thickness of stripper plate120(i.e., the shortest distance from female die surface122to outer surface138at any particular location) is generally uniform throughout the stripper plate120, though in various embodiments the wall thickness of stripper plate120may vary. Perforations124extend between and to female die surface122and outer surface138of stripper plate120.

Perforations114and/or perforations124may comprise round holes of between 0.05 inch and 0.75 inch (1.27 mm-19.05 mm) in diameter. Perforations114and/or perforations124may cover 50-99% of the base plate110and/or stripper plate120, respectively. Perforations114and/or perforations124may be spaced 0.075 inch to 1 inch (1.905 mm-25.4 mm) apart center-to-center, as measured either horizontally, vertically, or diagonally, depending on the location of the perforations114being measured. In various embodiments, perforations114and/or perforations123may constitute 20%-75% of the total surface area of the base plate110and/or stripper plate120, respectively.

In various embodiments, stripper plate120is a single piece component; though stripper plate120may also be formed as a two or more piece component (seeFIG.7AthroughFIG.8G).

FIG.4illustrates, in accordance with various embodiments, a perspective view of the base plate110. Base plate110extends longitudinally along a longitudinal centerline191of the base plate110(e.g., along a Y-axis) between and to a first end140of the base plate110and a second end141of the base plate110. The base plate110extends laterally (e.g., along an X-axis) between and to a first side142of the base plate110and a second side143of the base plate110. The base plate110extends vertically (e.g., along a Z-axis) between and to a bottom side144of the base plate110and a top side145of the base plate110.

The base plate110may be configured with at least one recess146; e.g., an aperture such as a pocket, a channel, a groove, etc. The recess146ofFIG.4extends (e.g., partially) vertically into the base plate110from one or more bottom surfaces147of the base plate110to a recess surface116of the base plate110, where the bottom surfaces147ofFIG.4are arranged on opposing sides of the recess surface116at the bottom side144. The recess146ofFIG.4extends longitudinally in (e.g., through) the base plate110, for example, between and to the base plate first end140and/or the base plate second end141. The recess146ofFIG.4extends laterally in (e.g., within) the base plate110, for example, between opposing lateral sides of the recess surface116.

The male die surface112is a convex or concave-convex surface and may have a curved geometry; e.g., a three-dimensional (3D) curvature. The male die surface112ofFIG.4, for example, has a curved (e.g., arcuate, splined, etc.) cross-sectional geometry in a lateral-vertical reference plane; e.g., an X-Z plane. The male die surface112may also have a curved (e.g., arcuate, splined, etc.) cross-sectional geometry in a longitudinal-vertical reference plane; e.g., a Y-Z plane. This recess curvature may change as the male die surface112/the recess146extends laterally and/or longitudinally, which may provide the male die surface112with a complex 3D curvature. In embodiments, the recess curvature may remain uniform as the male die surface112/the recess146extends laterally and/or longitudinally. The male die surface112may be configured without any sharp corners or sharp transitions.

In various embodiments, recess surface116generally follows the contour of male die surface112such that a wall thickness of base plate110(i.e., the shortest distance from recess surface116to male die surface112at any particular location) is generally uniform throughout the base plate110, though in various embodiments the wall thickness of base plate110may vary. Perforations114extend between and to male die surface112and recess surface116of base plate110.

In various embodiments, base plate110is a single piece component; though base plate110may also be formed as a two or more piece component (seeFIG.7AthroughFIG.8G). For example, with momentary reference toFIG.8AthroughFIG.8G) base plate110can comprise two or more pieces (e.g., first half211and second half212) moveable with respect to one another to conform to the shape and/or size of the fibrous preform102and/or support structure105. It should be understood that although illustrated as having a first half211and a second half212, base plate110can comprise any number of base plate sub-components that are configured together to define a male die surface112(seeFIG.6). Moreover, it is contemplated herein that the male die sub-components can interlock with one another similar to the stripper plate sub-components281,282, as described herein.

FIG.5illustrates, in accordance with various embodiments, tooling arrangement100further including a foam backing layer160disposed between fibrous preform102and base plate110. Foam backing layer160may be thick enough such that the needles150penetrate only into the foam backing layer160and not into the base plate110. This arrangement tends to allow for more flexibility in base plate110design, as the perforations114do not need to be aligned with the needling operation. In various embodiments, foam backing layer160provides structural support for the fibrous preform102during the z-needling process.

FIG.6illustrates, in accordance with various embodiments, tooling arrangement100further including a foam infill layer170disposed in the perforations114of base plate110. In this manner, the needles150may penetrate through the foam infill layer170. Providing foam infill layer170in perforations114tends to allow for more flexibility in base plate110design. Providing foam infill layer170in perforations114tends to aid in keeping needle orientation aligned (i.e., to keep the needles150from deflecting). For example, perforations114in base plate110can be larger for CVI densification while still supporting the needling operation. In various embodiments, foam infill layer170provides structural support for the fibrous preform102during the z-needling process.

FIG.7Aillustrates, in accordance with various embodiments, a conformable tooling arrangement200. Tooling arrangement200may be similar to tooling arrangement100, except that stripper plate220includes flexible joints226such that the stripper plate220may expand and conform to the shape of the fibrous preform102as layers are added to the fibrous preform102. Equipping stripper plate220with flexible joints226tends to ensure compression is appropriately applied to the fibrous preform102at each stage of manufacturing.

In various embodiments, stripper plate220can comprise two or more pieces (e.g., first half281and second half282) moveable with respect to one another to conform to the shape and/or size of the fibrous preform102. It should be understood that although illustrated as having a first half281and a second half282, stripper plate220can comprise any number of stripper plate sub-components that are configured together to define a female die surface122(seeFIG.6). In various embodiments, first half281comprises a first plurality of interlocking teeth283and second half comprises a second plurality of interlocking teeth284. First plurality of interlocking teeth283may be configured to interlock with second plurality of interlocking teeth284. In various embodiments, first plurality of interlocking teeth283interlock with second plurality of interlocking teeth284to lock the first half281from sliding longitudinally with respect to second half282.

In various embodiments, the flexible joint226may be selected from a variety of joints—tongue and groove, interlocking teeth, dovetail, etc. In various embodiments, the flexible joint226comprises a tongue and groove connection between a first half281of the stripper plate220and a second half282of the stripper plate220. The tongue and groove connection can be utilized to mitigate out of plane (e.g., the vertical direction or along the Z-direction) movement of the first half281with respect to the second half282.

In various embodiments, flexible joint226comprises a dovetail connection. The dovetail connection may lock the first half281from sliding laterally (along the X-direction) with respect to the second half282. In this manner, first half281and/or second half282may be replaced with different sized halves to accommodate different sized preforms102.

FIG.7Billustrates, in accordance with various embodiments, a conformable tooling arrangement201. Conformable tooling arrangement201may be similar to conformable tooling arrangement200. Flexible joint227comprises interlocking teeth whereby the first half281is slidably coupled to second half282. For example, the first plurality of interlocking teeth285and the second plurality of interlocking teeth286may lock the first and second halves281,282from sliding longitudinally (along the Y-direction) with respect to one another, but may allow the first and second halves281,282to freely slide laterally (along the X-direction) with respect to one another.

For example,FIG.8AthroughFIG.8Gillustrates a C/C part manufacturing process using conformable tooling arrangement201.

With reference toFIG.8A, the base plate110may be placed onto a mount or support structure105.

With reference toFIG.8B, the fibrous preform102is placed on the base plate110. In various embodiments, a first layer of the fibrous preform102is placed on the base plate110inFIG.8B. The fibrous preform102can conform to a shape of the base plate110.

With reference toFIG.8C, the stripper plate220is placed on top of the fibrous preform102. In various embodiments, first half281is placed over fibrous preform102and second half282is placed over fibrous preform102. InFIG.8C, the flexible joint227is moved to a contracted position, whereby the flexible joint227is closed or nearly closed (i.e., the first half281is moved against, or close to, the second half282).

With reference toFIG.8D, the stripper plate220can be removed and additional plies or layers can be added to the fibrous preform102. In this regard, the overall size of fibrous preform102can increase.

With reference toFIG.8E, the stripper plate220can again be placed over the fibrous preform102, though this time the first half281may be further spaced apart from the second half282due to the increased volume of the fibrous preform102. Although the flexible joint227is illustrated at a central location of the stripper plate220, flexible joint227may additionally or alternatively be placed at the corners (e.g., radii) of the stripper plate220. In various embodiments, the fibrous preform102is compressed between the base plate110and the stripper plate220. In various embodiments, the additional plies or layers can be successively needled each time a new layer is added, as desired (seeFIG.2).FIG.8Eillustrates the flexible joint227of the stripper plate220moved to an expanded position to conform to the plurality of layers of the fibrous preform102. In the expanded position, the first half281is moved away (e.g., laterally) from the second half282to accommodate the increased thickness of the fibrous preform102.

With reference toFIG.8F, the steps described with respect toFIG.8BthroughFIG.8Emay be repeated as desired, using the flexible joint227in stripper plate220to adjust to different thicknesses of the fibrous preform102.

With reference toFIG.8G, the conformable tooling arrangement201, together with fibrous preform102, can be loaded into a furnace for densification as desired. In various embodiments, a composite clamp500(seeFIG.10andFIG.11) can be installed over the base plate110and stripper plate220before placing the conformable tooling arrangement201into the furnace.

FIG.9is a flow chart for a method400for manufacturing a carbon-carbon component, in accordance with various embodiments. For ease of description, the method400is described below with reference toFIG.1throughFIG.6. The method400of the present disclosure, however, is not limited to use of the exemplary preform tooling arrangement100ofFIG.1throughFIG.6.

In step402, the fibrous preform102is provided. Fibrous preform102may be configured as a multi-layered preform. Fibrous preform102may be draped over base plate110, for example when fibrous preform102is made from one or more layers of carbon fiber sheets. Fibrous preform102may be placed over base plate110and compressed into the desired shape and fiber volume (e.g., using stripper plate120, for example when fibrous preform102is made from one or more layers of fabrics or sheets. The stripper plate120may be placed over the fibrous preform102to compress the fibrous preform102between the stripper plate120and the base plate110(seeFIG.1for example).

In step404, a the fibrous preform102undergoes a z-needling process in situ (i.e., while the fibrous preform102is installed between the stripper plate120and the base plate110). In various embodiments, and in preparation for the z-needling process, foam backing layer160disposed between fibrous preform102and base plate110(seeFIG.5) or foam infill layer170is disposed in the perforations114of base plate110(seeFIG.6). During the z-needling process, textile needles150are inserted through perforations124and at least partially into fibrous preform102to displace fibers in fibrous preform102to extend in the z-direction, thereby achieving desired interlaminar properties of the fibrous preform102. In various embodiments, during the z-needling process, textile needles150are inserted through perforations124and completely through fibrous preform102. In various embodiments, during the z-needling process, textile needles150are inserted through perforations124, completely through fibrous preform102, and at least partially into foam backing layer160. In various embodiments, during the z-needling process, textile needles150are inserted through perforations124, completely through fibrous preform102, and at least partially into foam infill layer170. In various embodiments, during the z-needling process, textile needles150are inserted through both perforations124and perforations114(e.g., in embodiments where perforations114and perforations124are aligned).

In various embodiments, a sizing agent is added to the fibrous preform102during the shape-forming process. For example, a sizing agent comprising a fluid and/or fluid vapor such as water, steam, and/or polyvinyl alcohol may be applied to the fibrous preform102(e.g., before being shape formed). Adding the sizing agent to the fibrous preform102may dampen the fibers thereof which tends to relax the fibers of the fibrous preform, thereby aiding in the bending, forming, and/or stretching of the fibrous preform. Adding the sizing agent to the fibrous preform102may also help to reduce wrinkling of the fibrous preform. Sizing may help to protect the fiber from handling damage and provide lubricity allowing the fibers to slide easily during the lay-up, needling and/or preforming/compaction process. Sizing agents of the present disclosure include water soluble polymers. The sizing agent may comprise a water solution. The sizing agent may comprise long chain alcohols such as polyvinyl alcohols, modified starch, cellulose gum such as carboxymethyl cellulose, modified wax, acrylates, and/or mixtures thereof. In various embodiments, up to about 700 mL (23.7 fluid oz) of water or more may be applied to the fibrous preform102, though the amount of water is a variable parameter based on a variety of factors, including the size and volume of the fibrous preform102. In various embodiments, approximately 1 milliliter (ml) of water may be added for every 2.5 cubic inches of fibrous preform (1 ml/2.5 in3), wherein the term approximately as used in this context can only mean ±0.5 ml. Stated differently, between 0.5 ml and 1.5 ml of water may be added to the fibrous preform for every 2.5 cubic inches of fibrous preform. However, it should be understood that other amounts of water or sizing agent may be added to the fibrous preform without departing from the scope of the present disclosure. Moreover, the fibrous preform may be preconditioned in a humidity chamber at a humidifying temperature (e.g., between 100° F. (37.8° C.) and 200° F. (93.3° C.)) and a relative humidity (e.g., between 75% and 90% humidity). Adding the sizing agent to the fibrous preform102may tend to reduce wrinkling of the fibrous preform102and support stabilizing the preform into the desired shape during the needling and shape-forming stages. In this manner, the fibrous preform102may be compressed to the desired fiber volume more easily and formed to shape using heat, moisture, pressure, stripper plate120, and base plate110, into the contoured shapes as desired for a particular C/C part application. In various embodiments, the sizing agents may also provide lubricity between the fibrous preform102and stripper plate120and/or between the fibrous preform102and base plate110, preventing the fibrous preform102from sticking to the stripper plate120and/or the base plate110, respectively.

In various embodiments, foam backing layer160or foam infill layer170may be made of a foam material that burns cleanly during the carbonization/heat-treatment or densification process (depending on which process is used immediately following z-needling). In this regard, foam backing layer160or foam infill layer170may burn away cleanly during the carbonization/heat-treatment or densification process—leaving just the fibrous preform102, stripper plate120, and base plate110. To accommodate shrinking of the fibrous preform102and/or burning away of the foam (particularly when foam backing layer160is used), graphite and/or C/C composite clamps may be used to maintain compression on fibrous preform102. For example, with reference toFIG.10, a composite clamp500is illustrated, in accordance with various embodiments. Clamp500includes a first clamp half502and a second clamp half504moveable with respect to the first clamp half502. A guide shaft506may extend from first clamp half502and into a guide slot or aperture508disposed in second clamp half504. Guide shaft506may align second clamp half504with first clamp half502and guide relative translation of second clamp half504with respect to first clamp half502.FIG.11is a section view of clamp500installed over base plate110and stripper plate120. In this illustrated embodiment, foam backing layer160is installed between base plate110and fibrous preform102. In this installed position, and prior to heat-treatment or densification, second clamp half504is spaced apart from first clamp half502by a distance590which is greater than the thickness591of foam backing layer160. In this manner, clamp500may close (i.e., second clamp half504moves toward first clamp half502, thereby closing, or partially closing, the distance590) as the foam backing layer is burned away in response to being heated to heat-treatment or densification temperatures. Moreover, distance590may be configured to accommodate shrinking of fibrous preform102. During the heat-treatment and/or densification steps, a force—represented by arrow592—maybe applied to clamp500to maintain compression on the fibrous preform102to set preform thickness and/or fiber volume as the foam backing layer160burns away, for example using a dead weight, a press, or the like. In this regard, the second clamp half504may be biased toward the first clamp half502while the preform tooling arrangement100is in the heat-treatment and/or densification furnace.

In various embodiments, after the z-needling process, foam backing layer160or foam infill layer170may be washed away in a water bath. In this regard, the foam backing layer160and/or foam infill layer170may comprise a washable foam. Removing the foam before heat-treatment and/or densification may tend to be desirable over burning away the foam in the furnace.

In step406, the fibrous preform102undergoes a heat-treatment process, particularly when the fibrous preform102is not already entirely, or nearly entirely (e.g., greater than 99%), carbon and contains no to very small amounts (<1%) sizing agents or resin binders. In this regard, step406may be optional. Stated differently, step406may be skipped when fibrous preform102is made of higher purity or high temperature carbon fibers.

Step406may be performed with fibrous preform102secured in compression within preform tooling arrangement100, particularly where preform tooling arrangement100is made from a graphite material, a C/C material, or other material suitable for withstanding heat-treatment and densification temperatures. The fibrous preform102(now a shaped body) may be heat treated to fully convert the fibrous preform102to a carbon preform. In various embodiments, fibrous preform102together with preform tooling arrangement100may be placed in a furnace for heat-treatment. The heat-treatment process may be employed to convert the fibers of the fibrous preform102into pure carbon fibers and to drive off any volatile species present in the fibrous preform102, for example, moisture and oxygen, hydrogen or nitrogen species present in the sizing agents. As used herein only “pure carbon fibers” means carbon fibers comprised of at least 95% carbon. Since the heat-treatment step helps to drive off most of the elements other than carbon from the fibrous preform, the heat-treatment process is sometimes referred to as carbonization. As used herein, heat-treatment and carbonization may be used interchangeably. The carbonization or heat-treatment process is distinguished from the densification process described below in that the densification process involves infiltrating the pores of the fibrous preform102and depositing a carbon matrix within and around the carbon fibers of the fibrous preform102, and the heat treatment or carbonization process refers to the process of converting the fibers of the fibrous preform102into pure carbon fibers.

The shape-formed fibrous preform102may be carbonized/heat-treated by placing the shape-formed fibrous preform102in a furnace with an inert atmosphere. In general, the carbonization process involves heating the shape-formed fibrous preform102in a furnace to a carbonization/heat-treatment temperature greater than about 1,000 degrees Celsius (1,832 Fahrenheit). Typically, an inert atmosphere of nitrogen, argon or a vacuum is provided in the furnace during the carbonization/heat-treatment process. The heat of the furnace converts the fibers to purer carbon fibers and drives off other chemicals. Although it is sometimes preferred that the fibers in the heat-treated fiber preform be 100% carbon fiber, it is generally acceptable for a less than full conversion to take place. The resulting heat-treated fiber preform generally has the same fibrous structure as the fibrous preform102before heat-treatment. During heat-treatment, the total mass and the total fiber volume in each fibrous preform102is typically reduced in proportion to the non-carbon compounds present in the fibrous preform102and driven off during the heat-treatment process.

In step408, the fibrous preform102(or heat-treated fibrous preform if step406is utilized) undergoes a CVI densification process. Step408may be performed after step406(or after step404when fibrous preform102is made from carbon fibers and step406is omitted). In this regard, the same preform tooling arrangement100may be conveniently used for shape-forming, z-needling, carbonization (optional), and CVI densification.

In general, densification involves filling the voids, or pores, of the fibrous preform102with additional carbon material. This may be done using the same furnace used for heat-treatment or a different furnace. Typically, chemical vapor infiltration and deposition (“CVI/CVD”) techniques are used to densify the porous fibrous preform102with a carbon matrix. This commonly involves heating the furnace and the carbonized preforms, and flowing hydrocarbon gases (e.g., at least one of methane, ethane, propane, butane, and/or the like, as described herein) into the furnace and around and through the fibrous preforms. In various embodiments, the CVI/CVD process may include a temperature gradient. In various embodiments, the CVI/CVD process may include a pressure gradient. In various embodiments, the CVI/CVD process may include a temperature and a pressure gradient.

CVI/CVD densification may be conducted in a vacuum or partial vacuum (e.g., at pressures of 1-15 torr) or in an inert atmosphere at a densification temperature in the range from about 650° C. to about 1425° C. (1,200° F. to about 2,600° F.), and in various embodiments in a range of about 900° C. to about 1100° C. (1,652° F. to about 2,012° F.), and in various embodiments in a range of about 815° C. to about 1040° C. (1,500° F. to about 1,900° F.), and in various embodiments in the range of up to about 1,000° C. (1,832° F.) (wherein the term about in this context only means +/−100° C.) for a period of time in the range from about 150 hours to about 650 hours, and in various embodiments, in the range from about 300 hours to about 500 hours (wherein the term about in this context only means +/−24 hours).

As a result, carbon from the hydrocarbon gases separates from the gases and is deposited on and within the fibrous preforms. Typically, the densification process is continued until the preform reaches a density in the range from 1.6 to 1.9 grams per cubic centimeter (g/cc), and in various embodiments, a density of approximately 1.80 g/cc. When the densification step is completed, the resulting C/C part has a carbon fiber structure with a carbon matrix infiltrating the fiber structure, thereby deriving the name “carbon/carbon.”

FIG.12is, in accordance with various embodiments, a section view of a portion of the preform tooling arrangement100during a densification process. Perforations124in stripper plate120and perforations114in base plate110aid in allowing the hydrocarbon gases195to infiltrate throughout the fibrous preform102during densification. In this regard, perforations114and/or perforations124may serve a dual purpose for z-needling and densification. In this regard, step408may further include flowing hydrocarbon gases195through perforations114and/or perforations124and into fibrous preform102.

After a first CVI/CVD cycle of 50 to 500 hours, an intermediate heat treat may be performed, in the same furnace. This heat treat (>1600° C.) serves to dimensionally stabilize the fibrous preform102, increase its thermal properties, and increase its porosity for subsequent densification. The fibrous preform102may then be taken out of the tool-assembly. That is the fibrous preform102with the CVI/CVD carbon may be separated from the stripper plate120and the base plate110and any clamps500. The outer surfaces of the fibrous preform102may be machined to open the porosity further, to help allow for final density to be achieved using only one more CVI/CVD cycle, with or without the tooling assembly around the fibrous preform102. Part densities after first machining may be in the range of 1.4 to 1.7 g/cc, depending on the part thickness, overall size, and placement within the furnace. Typical, average density range is 1.55-1.65 g/cc.

The densification process may be continued until the preform reaches a desired density, for example in the range from 1.7 to 1.9 grams per cubic centimeter (g/cc), and in various embodiments, a density of approximately 1.80 g/cc. The CVI/CVD process may be continued with the fibrous preform102removed from the perforated graphite fixture. In this manner, the outer surfaces of the fibrous preform102may be more directly exposed to the gas flow. Moreover, the fibrous preform102may be machined in between carbon CVI densification processes (e.g., between fixtured carbon CVI densification and non-fixtured carbon CVI densification and/or between successive non-fixtured carbon CVI densification processes). Machining (e.g., grinding, sanding, milling, grit blasting, etc.) the fibrous preform102may be performed to achieve a final desired part shape. Machining the fibrous preform102may be performed to expose voids, or pores, of the fibrous preform102so as to facilitate infiltration with additional carbon material during subsequent carbon CVI densification. When the densification step is completed, and the desired density is achieved, the resulting C/C part has a carbon fiber structure with a carbon matrix infiltrating the fiber structure, thereby deriving the name “carbon/carbon.”

Following the CVI/CVD densification process, the C/C part may undergo a final heat treatment (FHT) process. This may be done using the same furnace used for densification or a different furnace. If done using the same furnace, the flow of hydrocarbon gases would be stopped following the end of the densification process and the temperature increased. FHT may be conducted in a vacuum or partial vacuum (e.g., at pressures of 1-15 torr) or in an inert atmosphere at a temperature in the range from about 1200° C. to about 2600° C. (2,921° F. to about 4,712° F.), and in various embodiments in the range from about 1400° C. to about 2200° C. (2,552° F. to about 3,992° F.) (wherein the term about in this context only means +/−100° C.) for a period of time in the range from about 4 hours to about 14 hours, and in various embodiments, in the range from about 8 hours to about 12 hours (wherein the term about in this context only means +/−2 hours). In various embodiments, the FHT process imparts high temperature dimensional stability to the final C/C part. In various embodiments, the FHT process imparts desired thermal properties associated with thermal shock such as high thermal conductivity, high heat capacity, and/or high emissivity.

With reference toFIG.13, a base plate310is illustrated installed over a support structure105, in accordance with various embodiments. Although illustrated as have base plate sub-components311,312, base plate310may also comprise a single piece base plate, or may comprise any number of base plate sub-components, in accordance with various embodiments.

In various embodiments, the male die surface312may feature sub-regions that are locally concave together with regions that are convex along a direction of the die surface. Stated differently, a first sub-region391(along the Y-direction; also referred to as the longitudinal direction) of base plate310can be convex and a second sub-region392(along the Y-direction) of base plate310can be concave. In various embodiments, the male die surface312may be convex in one direction (see first sub-region391along the Y-direction) and concave in a different direction of the male die surface312(see third sub-region which is concave along the X-direction).

Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the invention. The scope of the invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is intended to invoke 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.