US20080116334A1 - Methods for fabricating composite structures having mounting flanges - Google Patents

Abstract

Methods for fabricating a composite structure having at least one mounting flange involving providing a composite structure forming tool having a first endplate and a second endplate, fabricating a composite structure preform about the tool, the composite structure preform having at least one mounting flange preform circumferentially oriented thereabout, placing at least one extended flange shoe having a first side and a second side circumferentially about the composite structure preform so that the first side lies adjacent to the first endplate, removeably coupling the first endplate to the first extended flange shoe, placing at least one flange shoe circumferentially about the composite structure preform adjacent to the second end of the extended flange shoe, removeably coupling the flange shoe to the extended flange shoe to form a cavity about the mounting flange preform, and curing the composite structure preform having the at least one mounting flange preform to obtain a composite structure having at least one mounting flange.

Description

TECHNICAL FIELD
• Embodiments described herein generally relate to methods for fabricating composite structures having mounting flanges. More particularly, embodiments herein generally describe methods for using final cure tooling to fabricate composite structures having mounting flanges.
BACKGROUND OF THE INVENTION
• In gas turbine engines, such as aircraft engines, air is drawn into the front of the engine, compressed by a shaft-mounted compressor, and mixed with fuel in a combustor. The mixture is then burned and the hot exhaust gases are passed through a turbine mounted on the same shaft. The flow of combustion gas expands through the turbine which in turn spins the shaft and provides power to the compressor. The hot exhaust gases are further expanded through nozzles at the back of the engine, generating powerful thrust, which drives the aircraft forward.
• Because engines operate in a variety of conditions, foreign objects may undesirably enter the engine. More specifically, foreign objects, such as large birds, hailstones, sand and rain may be entrained in the inlet of the engine. As a result, these foreign objects may impact a fan blade and cause a portion of the impacted blade to be torn loose from the rotor, which is commonly known as fan blade out. The loose fan blade may then impact the interior of the fan casing causing a portion of the casing to bulge or deflect. This deformation of the casing may result in increased stresses along the entire circumference of the engine casing.
• In recent years composite materials have become increasingly popular for use in a variety of aerospace applications because of their durability and relative lightweight. Although composite materials can provide superior strength and weight properties, and can lessen the extent of damage to the fan casing during impacts such as blade outs, designing flanges on structures fabricated from composite materials still remains a challenge.
• Current fabrication methods can generally provide for the construction of composite structures having end flanges. See, for example, U.S. Patent Application No. 2006/0134251 to Blanton et al. However, difficulties may arise when trying to fabricate composite structures having interposing mounting flanges, which are situated about the body, as opposed to an end, of the composite structure. These difficulties may be due in part to the fact that the tooling needed to fabricate such interposing mounting flanges lacks the support necessary to ensure the flange will have the proper shape, dimension and placement after final curing, as explained below.
• Fabrication of end flanges typically includes any of a variety of resin infusion processes. In one embodiment, a dry fiber preform may be packed into a mold cavity having the desired part shape and the mold can be closed. Resin may then be applied, typically under pressure or vacuum, into the mold where it can impregnate the preform. After the fill cycle, the cure cycle begins, during which the mold may be heated and the resin can polymerize to become a rigid plastic part. Alternately, dry fiber preforms can be impregnated with resin using rollers or brushes to force the resin into the fabric. The impregnated preform may then be packed into a mold or cavity. A cure cycle then begins during which a rigid plastic part can be formed without having to infuse the mold cavity with any additional resin.
• In contrast to end flanges, fabrication of interposing mounting flanges requires tooling capable of being situated in a variety of locations along the body of the composite structure. Unlike the end flange shoes, or molds, which can be attached to and supported by the tool itself, the flange shoes needed to cure interposing mounting flanges have nothing to which to attach. Without this added support, the mounting flange tooling can be more likely to shift and move about during the final curing step, resulting in improper formation of the mounting flange.
• Accordingly, there remains a need for methods for fabricating composite structures having interposing mounting flanges that utilizes tooling that remains in place during final cure to help ensure the mounting flanges have the desired shape and position.
BRIEF DESCRIPTION OF THE INVENTION
• Embodiments herein generally relate to methods for fabricating a composite structure having at least one mounting flange comprising providing a composite structure forming tool having a first endplate and a second endplate; fabricating a composite structure preform about the tool, the composite structure preform having at least one mounting flange preform circumferentially oriented thereabout; placing at least one extended flange shoe having a first side and a second side circumferentially about the composite structure preform so that the first side lies adjacent to the first endplate; removeably coupling the first endplate to the first extended flange shoe; placing at least one flange shoe circumferentially about the composite structure preform adjacent to the second end of the extended flange shoe; removeably coupling the flange shoe to the extended flange shoe to form a cavity about the mounting flange preform; and curing the composite structure preform having the at least one mounting flange preform to obtain a composite structure having at least one mounting flange.
• Embodiments herein also generally relate to methods for fabricating a composite structure having mounting flanges comprising providing a composite structure forming tool having a first endplate and a second endplate; fabricating a composite structure preform about the tool, the composite structure preform having a first mounting flange preform and a second mounting flange preform circumferentially oriented thereabout; placing a first extended flange shoe having a first side and a second side circumferentially about the composite structure preform so that the first side lies adjacent to the first endplate; removeably coupling the first endplate to the first extended flange shoe; placing a first flange shoe circumferentially about the composite structure preform adjacent to the second end of the first extended flange shoe; removeably coupling the first flange shoe to the first extended flange shoe to form a cavity about the first mounting flange preform; placing a second extended flange shoe having a first side and a second side circumferentially about the composite structure preform so that the first side lies adjacent to the second endplate; removeably coupling the second endplate to the second extended flange shoe; placing a second flange shoe circumferentially about the composite structure preform adjacent to the second side of the second extended flange shoe; removeably coupling the second flange shoe to the second extended flange shoe to form a cavity about the second mounting flange preform; and curing the composite structure preform having the mounting flange performs to obtain a composite structure having mounting flanges.
• Embodiments herein also generally relate to methods for fabricating a composite structure having adjacent mounting flanges comprising providing a composite structure forming tool having a first endplate and a second endplate; fabricating a composite structure preform about the tool, the composite structure preform having a first mounting flange preform adjacent to a second mounting flange preform circumferentially oriented thereabout; placing a first extended flange shoe having a first side and a second side circumferentially about the composite structure preform so that the first side lies adjacent to the first endplate; removeably coupling the first endplate to the first extended flange shoe; placing a second extended flange shoe having a first side and a second side circumferentially about the composite structure preform so that the first side of the second extended flange shoe is adjacent to the second side of the first extended flange shoe; removeably coupling the second extended flange shoe to the first extended flange shoe to form a cavity about the first mounting flange preform; placing a first flange shoe circumferentially about the composite structure preform adjacent to the second side of the second extended flange shoe; removeably coupling the first flange shoe to the second extended flange shoe to form a cavity about the second mounting flange preform; and curing the composite structure preform having the adjacent mounting flange preforms to obtain a composite structure having adjacent mounting flanges.
• These and other features, aspects and advantages will become evident to those skilled in the art from the following disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
• While the specification concludes with claims particularly pointing out and distinctly claiming the invention, it is believed that the embodiments set forth herein will be better understood from the following description in conjunction with the accompanying figures, in which like reference numerals identify like elements.
• FIG. 1 is a schematic cross-sectional view of one embodiment of a gas turbine engine;
• FIG. 2 is a schematic view of one embodiment of a fan casing having a mounting flange;
• FIG. 3 is a schematic perspective view of one embodiment of a composite structure forming tool;
• FIG. 4 is a schematic cross-sectional view of one embodiment of a mounting flange operably connected to a fan casing;
• FIG. 5 is a schematic view of one embodiment of a fan casing having mounting flanges and attached secondary structure;
• FIG. 6 is a schematic representation of one embodiment of a process for fabricating a mounting flange;
• FIG. 7 is a schematic cross-sectional view of one embodiment of a flange shoe;
• FIG. 8 is a schematic cross-sectional view of one embodiment of an extended flange shoe;
• FIG. 9 is a schematic cross-sectional view of one embodiment of tooling used during final cure of a composite fan casing having two mounting flanges; and
• FIG. 10 is a portion of a schematic cross-sectional view of one embodiment of tooling used during final cure of a composite fan casing having two adjacent mounting flanges.
DETAILED DESCRIPTION OF THE INVENTIONIntegral Composite Mounting Flanges
• Embodiments described herein generally relate to methods for fabricating mounting flanges that utilize tooling that remains in place during final cure to help ensure the mounting flanges have the proper placement and dimensions. While embodiments herein may generally focus on tooling used to cure mounting flange preforms on composite fan casing preforms of gas turbine engines, it will be understood by those skilled in the art that the description should not be limited to such. Indeed, as the following description explains, the tooling described herein may be used to cure mounting flange preforms on any composite structure.
• Turning to the figures,FIG. 1 is a schematic representation of one embodiment of agas turbine engine10 that generally includes afan assembly12 and acore engine14.Fan assembly12 may include afan casing16 and an array offan blades18 extending radially outwardly from arotor disc20.Core engine14 may include a high-pressure compressor22, acombustor24, a high-pressure turbine26 and a low-pressure turbine28.Engine10 has anintake side30 and anexhaust side32.Fan assembly12 and low-pressure turbine28 may be coupled by afirst rotor shaft34 while high-pressure compressor22 and high-pressure turbine26 may be coupled by asecond rotor shaft36.
• FIG. 2. illustrates one embodiment of an acceptableprimary composite structure38. As used herein, “composite structure (preform)” refers to any component, or preform thereof fabricated from composite materials.Composite structure38 may comprise a generally cylindrical member, such asfan casing16. Henceforth, the cylindrical member will be referred to asfan casing16, though it should not be limited to such.Fan casing16 may be generally cylindrical in shape and may be fabricated from any acceptable material. In one embodiment, however,fan casing16 may be fabricated from a composite material, such as, but not limited to, glass fibers, graphite fibers, carbon fibers, ceramic fibers, aromatic polyamide fibers such as poly(p-phenylenetherephtalamide) fibers (i.e. KEVLAR®), and combinations thereof. In one embodiment, the composite material may comprise carbon fibers. Additionally,fan casing16 may be fabricated using any acceptable fabrication method known to those skilled in the art. See, for example, U.S. Patent Application No. 2006/0201135 to Xie et al.
• Fan casing16 may generally comprise abody40 having aforward end42 and anaft end44. As used herein, “fan casing” is used to refer to both pre- and post-cure composite fan casings. Those skilled in the art will understand which stage is being referenced from the present description.Fan casing16 may also comprise at least one integralcomposite mounting flange46. As used herein, “mounting flange” refers to any flange interposed circumferentially aboutbody40 offan casing16, or other primary composite structure, that may be used to operably connect a secondary structure to the primary structure, as described herein below. By “interposed” it is meant that mountingflange46 may be located circumferentially aboutbody40 offan casing16, as opposed to about either offorward end42 oraft end44.
• Fan casing16 may also be fabricated using any tool known to those skilled in the art. See, for example, U.S. Patent Application No. 2006/0134251 to Blanton et al. In one embodiment, as shown inFIG. 3, compositestructure forming tool37 may have a circumference, a generally cylindrically shapedcore33, and comprise afirst endplate72 and asecond endplate84 that may be removeably attached tocore33 oftool37.
• Turning toFIG. 4, integralcomposite mounting flange46 may generally include at least onecore fiber52, though in oneembodiment mounting flange46 may comprise a plurality ofcore fibers52.Core fibers52 may be circumferentially oriented aboutfan casing16. By “circumferentially oriented” it is meant thatcore fibers52, whether fiber tows, textile preforms or a combination thereof, generally circumscribefan casing16 and are continuous in the circumferential direction. Mountingflange46 may also generally comprise at least one layer ofmultidirectional attachment fibers54 that may operably connectcore fibers52 tofan casing16 as described herein below. As used herein, “multidirectional” refers to textile preforms comprising the attachment fibers that have fiber tows oriented in more than one direction.
• As will be understood by those skilled in the art,core fibers52 may be fabricated in different ways. In one embodiment,core fibers52 may be fabricated from a plurality of continuous, unidirectional fiber tows bundled and bonded together. In another embodiment,core fibers52 may comprise textile preforms, such as a flattened biaxial braid sleeve, having a majority of fiber tows that are continuous in the circumferential direction, and the remaining fibers either continuous or non-continuous in the non-circumferential direction. It is this general circumferential orientation ofcore fibers52 that can provide added strength to the flange in the circumferential direction as explained herein below. Regardless of the particular assembly utilized,core fibers52 may comprise afirst core side56 and asecond core side58.
• Fiber tows ofcore fibers52 may be comprised of any suitable reinforcing fiber known to those skilled in the art, including, but not limited to, glass fibers, graphite fibers, carbon fibers, ceramic fibers, aromatic polyamide fibers such as poly(p-phenylenetherephtalamide) fibers (i.e. KEVLAR®), and combinations thereof. Additionally, while any number of fiber tows may be used to constructcore fibers52, in one embodiment there may be from about 100 to about 5000 fiber tows used to constructcore fibers52. Moreover, each fiber tow may comprise from about 3000 to about 24,000 fiber filaments. In general, when assembled,core fibers52 may constitute about half of the overall thickness T of mountingflange46. While the thickness of mountingflange46 may vary according to application, in one embodiment, mountingflange46 may have a thickness of from about 0.5 inches (1.27 cm) to about 1 inch (2.54 cm).
• As explained previously, in addition tocircumferential core fibers52, each mountingflange46 may also include at least one layer ofattachment fibers54 operably connecting each offirst core side56 andsecond core side58 ofcore fibers52 tofan casing16. Unlikecore fibers52,attachment fibers54 may be constructed of multidirectional textile preforms, such as weaves or braids, that need not have a majority of fiber tows oriented circumferentially. In this way,attachment fibers54 can display a generally uniform strength distribution throughout. As with the core fibers, each fiber tow ofattachment fibers54 may comprise from about 3000 to about 24,000 fiber filaments. Generally, when assembled,attachment fibers54 may constitute the remaining half of the overall thickness offlange46.
• As illustrated inFIG. 5, mountingflange46, once cured, may be used to operably connect at least onesecondary structure48 tofan casing16 and thus,flange46 may be located in a variety of locations along the length ofbody40 offan casing16. In some instances, it may be desirable to include more than one mountingflange46. As shown inFIG. 5, in one embodiment,secondary structure48 may be, for example, anaccessory gear box50 that can be mounted tofan casing16 using the mountingflanges46 and any attachment method known to those skilled in the art, such as bolts. Other possible secondary structures may include, but are not limited to, an oil tank, oil and fuel monitoring modules, other engine externals and combinations thereof. It will be understood that “engine externals” refers to any accessory, module or component that may be connected to the outside of the engine. Such secondary structures may be constructed of any acceptable material known to those skilled in art such as, for example, aluminum, and as described previously may weigh significantly more than the corresponding fan casing to which they are attached. For example, in one embodiment,fan casing16 may weight about200 pounds whileaccessory gear box50 may weigh about 300 pounds.
• Embodiments of the mounting flange described herein can provide several benefits over existing attachment mechanisms. In particular, the integral mounting flange can reduce the occurrence of severe part damage to both the primary composite structure, as well as the attached secondary structure, while concurrently helping to eliminate catastrophic part failure. Without intending to be limited by theory, it is believed that, in general, fiber-reinforced composite structures, such as the mounting flanges herein, can have relatively weak interfaces between fiber layers and, therefore, have relatively weak through-thickness strength compared to their in-plane strength. If stresses on the composite structure exceed a defined maximum capacity level, these fiber layers can have a tendency delaminate, or separate, prior to actual fiber breakage occurring. This delamination or separation can reduce the load and stress on the attachment joint where the mounting flange connects to the primary structure. As will be understood by those skilled in the art the maximum stress capacity level of the primary composite structure can vary depending on such factors as materials of fabrication, method of fabrication and the like.
• Embodiments set forth herein are designed take advantage of the previously described phenomenon. More specifically, the integral mounting flange may be fabricated to permit delamination, or even separation, of the flange from the primary composite structure at the joint under excessive stresses, such as those caused by a fan blade out or by the weight of an attached secondary structure. However, because the core fibers of the flange can be constructed from continuous, circumferentially oriented fibers, even after delamination or separation the flange can remain a movable yet intact ring about the primary structure. Thus, even if the integral mounting flange delaminates or separates from the primary composite structure, it generally remains in place with all secondary structures attached. This can allow stresses on both the primary composite structure and the mounting flange to be reduced while maintaining the attached secondary structure in the same general placement as originally intended. Because of this, the delamination or separation can reduce damage to both the primary and secondary structures, as well as help to prevent catastrophic part failure.
Methods of Fabricating Integral Composite Mounting Flange
• Fabricating a mounting flange as set forth herein may generally comprise applying core fibers about the primary composite structure, followed by applying attachment fibers to operably connect the core fibers to the fan casing, or other primary composite structure. More specifically, as shown inFIG. 6,step100, the fabrication of a mounting flange may begin with providing a primary composite structure having a circumference, such asfan casing16. In one embodiment, the primary composite structure may be complete except for final cure. In step102 a correspondingly shapedguide60 may then be placed aboutbody40 offan casing16 in each location where a mounting flange is desired.Guide60 may be removably held in place by shrink tape, for example. In one embodiment, guide60 may be comprised of discrete arcuate members, each spanning about180 degrees ofbody40 offan casing16. The arcs ofguide60 may be releaseably connected together for easy placement and adjustment aboutfan casing16. It will be understood, however, thatguide60 may be comprised of any number of pieces and have any shape that corresponds to the shape of the primary composite structure.Guide60 can serve as a support for the later application of both the core fibers and the attachment fibers, as explained herein below. As previously mentioned, guide60 may be circumferential and have an L-shaped cross-section as shown, and may be constructed from any rigid, lightweight material such as, for example, aluminum or composite.
• Instep104, once all guides60 have been placed in the desired locations aboutbody40 offan casing16, the application ofcore fibers52 may be initiated. As previously discussed,core fibers52 may comprise either unidirectional, circumferentially oriented fiber tows bundled and bonded together or textile preforms, such as a flattened biaxial braid sleeve, having a majority of continuous, circumferentially oriented fiber tows.
• If unidirectional fiber tows are used to constructcore fibers52, the tows may comprise fiber filaments that can be wound about thefan casing16. In general, a single tackified fiber tow can be precisely placed in the desired position about the fan casing and this process can be repeated untilcore fibers52 have the desired size and shape. A debulking step may then be carried out to consolidatecore fibers52, as described herein below. Alternately, if textile preforms are used to constructcore fibers52, the textile layers can be layed-up and tackified on a flat, non-porous surface, such as a table or a tool. More specifically, the tackified textile layers can be stacked to form the core fibers'52 desired thickness and height, while still being long enough to circumscribe the fan casing. After debulking, as set forth below, the consolidated textile layers remain flexible enough to allow the layers to be manually or mechanically shaped into the proper radius to fit the fan casing, or other primary composite structure. Regardless of which type of fibers are used, finishedcore fibers52 may havefirst core side56 andsecond core side58.
• Having positionedcore fibers52 in the desired location aboutfan casing16,attachment fibers54 may be applied to each offirst core side56 andsecond core side58 ofcore fibers52, as well as to fan casing16 to operably connectcore fibers52 tofan casing16. Instep106, guide60 can be left in place whileattachment fibers54 are applied to, for example,first core side56 ofcore fibers52. As previously described,attachment fibers54 may comprise multidirectional textile preform layers, such as weaves or braids. Layers ofattachment fibers54 may be wrapped against bothfirst core side56 ofcore fibers52 andfan casing16 until the desired thickness is obtained. More specifically, a liquid resin, such as an epoxy, may be applied tocore fibers52 andfan casing16 to provide a tacky layer to whichattachment fibers54 may be applied. Next, a layer ofattachment fibers54 may be applied over the liquid resin. This process can be repeated until the desired thickness ofattachment fibers54 is achieved. Thoughattachment fibers54 may have any thickness, in one embodiment, the thickness of attachment fibers may be from about 0.125 inches (about 0.3 cm) to about 0.25 inches (about 0.6 cm).
• Onceattachment fibers54 have been applied tofirst core side56 of core fibers52 a debulk may again be performed to consolidate the construction thus far. In particular, reinforcing fibers, such ascore fibers52 andattachment fibers54, may inherently have a substantial amount of bulk. In order to help prevent wrinkles and/or voids during the final cure of the composite, and to utilize near net shape tooling during the final cure, the fibers of the composite can be consolidated, or compressed, into a dimension that is closer to the desired final cured thickness. This consolidation occurs during debulk.
• Debulk can be carried out using any common method known to those skilled in the art, such as, for example, by applying pressure to the composite fibers with either a vacuum bag, shrink tape, or other mechanical means. Resin applied to the fibers before debulk can help “tack,” or lock, the fibers in place once the pressure is applied. If the tackified fibers cannot be consolidated as desired at room temperature, then heat may be applied to lower the viscosity of the resin. The resin may then better infiltrate the composite fibers and allowing the consolidation to be carried out to the desired degree. In one embodiment, the guide may be left in place during the debulk process to provide support during fabrication.
• After debulk, guide60 may be repositioned adjacent to the completed side of the flange for the application ofattachment fibers54 to the opposing side of the flange as shown instep108. The previously described application and debulk ofattachment fibers54 may then be repeated on, for example,second core side58 ofcore fibers52, to obtain an integral composite mounting flange perform61 instep110.
• Optionally, in one embodiment shown instep112, additional individual fiber tows62 may be applied toattachment fibers54 of mountingflange preform61 prior to final cure to provide additional hoop strength. Such fiber tows will not affect the final cure of the composite structure. However, to avoid limiting the weight-saving benefits provided by using composite materials, it may be desirable to minimize the use of additional individual fiber tows62.
• Oncecore fibers52,attachment fibers54, and optionally individual fiber tows62, have been layed-up and debulked, each guide60 can be removed and the final cure tooling can be placed aboutfan casing16, including any flange performs, to serve as a mold during the curing process. As will be understood by those skilled in the art, the final cure tooling and process may vary according to such factors as resin used, part geometry, and equipment capability. However, in one embodiment, the tooling may comprise near net shape tooling, which not only helps prevent waste of raw material and machining time, but also eliminates having to machine into the attachment fibers, which could result in breaking the fibers and introducing weak points in the flange.
• In general, thefinal cure tooling64 may comprise various combinations of flange shoes and extended flange shoes. Flange shoes66 may comprise any number of pieces that when coupled together may be positioned circumferentially aboutfan casing16, and optionally mounting flange performs61, and may comprise a substantially L-shaped cross-section, as shown inFIG. 7. Extended flange shoes68, shown inFIG. 8, may have afirst side69 and asecond side71 and may also comprise any number of pieces that when coupled together may be positioned circumferentially aboutfan casing16, and optionally mounting flange performs61. Extended flange shoes68 may comprise a substantially U-shaped cross-section, as shown inFIG. 8. Bothflange shoes66 andextended flange shoes68 may be constructed of any material having a greater thermal coefficient of expansion than the fan casing preform. In one embodiment, flange shoes66 andextended flange shoes68 may be constructed from metals, alloys or combinations thereof, such as aluminum or steel. Additionally, as explained herein below, either or both offlange shoes66 andextended flange shoes68 may comprise a flange cavity to accommodate an end flange preform or a mounting flange preform.
• More particularly, as shown inFIG. 9, a firstextended flange shoe70 may be placed aboutfan casing16 such thatfirst side69 of firstextended flange shoe70 is adjacent to afirst endplate72 of the composite structure-formingtool74 upon whichfan casing16 is fabricated. Firstextended flange shoe70 may be removeably coupled to thefirst endplate72 using any attachment method known to those skilled in the art, such as, for example, bolts. Once positioned, firstextended flange shoe70 may overlay any firstend flange preform76 present, and continue alongbody40 offan casing16 to a first mountingflange preform78, as shown inFIG. 9. Afirst flange shoe80 may then be positioned aboutfan casing16, adjacent tosecond side71 of firstextended flange shoe70 and the two may be removeably coupled together about first mountingflange preform78. In this way, firstextended flange shoe70 can serve as an endplate tofirst flange shoe80 and provide the support necessary to help ensurefirst flange shoe80 remains in position such that first mountingflange preform78 retains its desired shape and orientation aboutfan casing16 during final cure.
• As also shown inFIG. 9, a secondextended flange shoe82 may be placed aboutfan casing16 such that afirst side69 of secondextended flange shoe82 is adjacent to asecond endplate84 of composite structure-formingtool74. Secondextended flange shoe82 may be removeably coupled to thesecond endplate84 in the same manner provided above for firstextended flange shoe70. Again, secondextended flange shoe82 may overlay any secondend flange preform86 present, and continue alongbody40 offan casing16 to a second mountingflange preform88, as shown inFIG. 9. Asecond flange shoe90 may then be positioned aboutfan casing16 adjacent tosecond side71 of secondextended flange shoe82 and the two may be removeably coupled together about second mountingflange preform88. As before, secondextended flange shoe82 can provide support tosecond flange shoe90 and help ensuresecond flange shoe90 remains in position such that second mountingflange preform88 retains its desired shape and orientation aboutfan casing16 during final cure.
• For each coupling of an extended flange shoe and a flange shoe, there may also be a flange-shaped cavity formed to accommodate any mounting flange preform. It will be understood by those skilled in the art that cavity may be formed in a flange shoe, an extended flange shoe, or a combination thereof. For example, inFIG. 9, firstextended flange shoe70 contains acavity92 to accommodate first mountingflange preform78 whilesecond flange shoe90 contains acavity92 to accommodate second mountingflange preform88.Additional cavities92 may be included to account for end flanges if present.
• As shown inFIG. 10, if adjacent mounting flange performs are present, a firstextended flange shoe70, having afirst side69 andsecond side71, may be removeably coupled to a secondextended flange shoe82, having afirst side69 andsecond side71, to form acavity92 therebetween about a first mountingflange preform78. Afirst flange shoe80 may then be removeably coupled tosecond side71 of secondextended flange shoe82 in the manner described above to form anothercavity92 about a second mountingflange preform88. Indeed, any number of extended flange shoes may be coupled together in this manner to accommodate a fan casing having multiple adjacent mounting flange performs to help ensure the flange performs have the support needed to remain properly positioned and proportioned.
• Once all flange shoes and extended flange shoes have been coupled together about the fan casing and the mounting flange performs, the final cure of the fan casing may commence. Those skilled in the art will understand how to determine the proper final cure parameters based on such factors as part size and resin utilized. At the end of the final cure, the tooling may be removed and an article including a composite structure having at least one mounting flange is obtained and any desired secondary structure may then be attached thereto.
• This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims (19)

1. A method for fabricating a composite structure having at least one mounting flange comprising:

providing a composite structure forming tool having a first endplate and a second endplate;

fabricating a composite structure preform about the tool, the composite structure preform having at least one mounting flange preform circumferentially oriented thereabout;

placing at least one extended flange shoe having a first side and a second side circumferentially about the composite structure preform so that the first side lies adjacent to the first endplate;

removeably coupling the first endplate to the first extended flange shoe;

placing at least one flange shoe circumferentially about the composite structure preform adjacent to the second end of the extended flange shoe;

removeably coupling the flange shoe to the extended flange shoe to form a cavity about the mounting flange preform; and

curing the composite structure preform having the at least one mounting flange preform to obtain a composite structure having at least one mounting flange.

2. The method ofclaim 1 wherein the extended flange shoe is constructed of any material having a greater thermal coefficient of expansion than the composite structure preform.

3. The method ofclaim 1 wherein the flange shoe is constructed of any material having a greater thermal coefficient of expansion than the composite structure preform.

4. The method ofclaim 1 wherein the composite structure preform is a fan casing.

5. The method ofclaim 1 wherein the extended flange shoe is constructed of a material selected from the group consisting of metals, alloys and combinations thereof.

6. The method ofclaim 1 wherein the flange shoe is constructed of a material selected from the group consisting of metals, alloys and combinations thereof.

7. The method ofclaim 1 wherein the flange shoe comprises a substantially L-shaped cross-section.

8. The method ofclaim 1 wherein the extended flange shoe comprises a substantially U-shaped cross-section.

9. A method for fabricating a composite structure having mounting flanges comprising:

providing a composite structure forming tool having a first endplate and a second endplate;

fabricating a composite structure preform about the tool, the composite structure preform having a first mounting flange preform and a second mounting flange preform circumferentially oriented thereabout;

placing a first extended flange shoe having a first side and a second side circumferentially about the composite structure preform so that the first side lies adjacent to the first endplate;

removeably coupling the first endplate to the first extended flange shoe;

placing a first flange shoe circumferentially about the composite structure preform adjacent to the second end of the first extended flange shoe;

removeably coupling the first flange shoe to the first extended flange shoe to form a cavity about the first mounting flange preform;

placing a second extended flange shoe having a first side and a second side circumferentially about the composite structure preform so that the first side lies adjacent to the second endplate;

removeably coupling the second endplate to the second extended flange shoe;

placing a second flange shoe circumferentially about the composite structure preform adjacent to the second side of the second extended flange shoe;

removeably coupling the second flange shoe to the second extended flange shoe to form a cavity about the second mounting flange preform; and

curing the composite structure preform having the mounting flange performs to obtain a composite structure having mounting flanges.

10. The method ofclaim 9 wherein the extended flange shoes are constructed of any material having a greater thermal coefficient of expansion than the composite structure preform.

11. The method ofclaim 9 wherein the flange shoes are constructed of any material having a greater thermal coefficient of expansion than the composite structure preform.

12. The method ofclaim 9 wherein the composite structure preform is a fan casing.

13. The method ofclaim 9 wherein the extended flange shoes are constructed of a material selected from the group consisting of metals, alloys and combinations thereof.

14. The method ofclaim 9 wherein the flange shoes are constructed of a material selected from the group consisting of metals, alloys and combinations thereof.

15. The method ofclaim 9 wherein the flange shoes comprise a substantially L-shaped cross-section.

16. The method ofclaim 9 wherein the extended flange shoes comprise a substantially U-shaped cross-section.

17. A method for fabricating a composite structure having adjacent mounting flanges comprising:

providing a composite structure forming tool having a first endplate and a second endplate;

fabricating a composite structure preform about the tool, the composite structure preform having a first mounting flange preform adjacent to a second mounting flange preform circumferentially oriented thereabout;

placing a first extended flange shoe having a first side and a second side circumferentially about the composite structure preform so that the first side lies adjacent to the first endplate;

removeably coupling the first endplate to the first extended flange shoe;

placing a second extended flange shoe having a first side and a second side circumferentially about the composite structure preform so that the first side of the second extended flange shoe is adjacent to the second side of the first extended flange shoe;

removeably coupling the second extended flange shoe to the first extended flange shoe to form a cavity about the first mounting flange preform;

placing a first flange shoe circumferentially about the composite structure preform adjacent to the second side of the second extended flange shoe;

removeably coupling the first flange shoe to the second extended flange shoe to form a cavity about the second mounting flange preform; and

curing the composite structure preform having the adjacent mounting flange preforms to obtain a composite structure having adjacent mounting flanges.

18. The method ofclaim 1 wherein the flange shoes comprise a substantially L-shaped cross-section.

19. The method ofclaim 1 wherein the extended flange shoes comprise a substantially U-shaped cross-section.

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