CN107407154B - Fragile composite airfoil - Google Patents

Abstract

The present disclosure provides a rotary machine (10) having at least one frangible composite blade (40), the frangible composite blade (40) mitigating adverse conditions associated with material release caused by impact damage to the composite blade (40). The composite blade (40) has functions for dissipating energy, self-shredding, and predetermined release trajectories. A method for manufacturing the composite blade (40), assembling the blade into a rotary machine (10), and operating the self-pulverizing blade (40) is also provided.

Description

Fragile composite airfoil

Statement regarding federally sponsored research

Is free of

CROSS-REFERENCE TO PRIORITY INFORMATION AND RELATED APPLICATIONS

This application claims priority from the following U.S. patent applications: darek Zatoski, entitled "A method of manufacturing a frangible blade," U.S. patent application Ser. No.14/596,841, the entire contents of which are incorporated herein by reference; U.S. patent application Ser. No.14/596,815 to Darek Zatoski entitled "A rotarymachine with a breakable composite blade," the entire contents of which are incorporated herein by reference; and Darek zotarski, U.S. patent application serial No.14/596,804 entitled "a frangible airfoil," the entire contents of which are incorporated herein by reference.

Technical Field

The field of the invention relates generally to rotary machines, and more particularly to airfoils for rotary machines. The present embodiments generally relate to an airfoil for a fan module of an aircraft mounted gas turbine engine. More specifically, the present airfoil embodiments relate to, but are not limited to, composite fan blades or propellers that mitigate adverse conditions associated with the release of material caused by impact damage.

Background

At least some known rotary machines, such as gas turbine engines, some of which are used for aircraft propulsion, include a plurality of rotating blades or propellers that are part of a fan module that channels air downstream. Although some single-rotation turboprop engines have been considered for higher cruise speeds, conventional single-rotation turboprop gas turbine engines provide high efficiency at low airspeed cruise speeds for flight mach numbers up to about 0.7. Higher cruise speeds at mach numbers of 0.7 to 0.9 are typically achieved with ducted fan gas turbine engines to produce the relatively high thrust required. Unducted counter-rotating propeller gas turbine engine, commonly referred to as a ductless fan (registered trade mark of general electric company)) Or open rotors, have been developed to deliver the high thrust required for high cruise speeds with greater efficiency than ducted fans. These blades and propellers have some tolerance for foreign debris ingested by the engineBut the ingestion of foreign objects can still cause the release of damaged portions of the rotating blades or propellers and can therefore improve these blades and propellers.

Disclosure of Invention

In one aspect, embodiments of the invention relate to an airfoil having a composite blade with a root, a tip, and a span therebetween, along with leading and trailing edges with a chord therebetween, the blade having at least one energy dissipating member comprising a pocket.

In another aspect, embodiments of the invention relate to an energy dissipating member extending along a span and chord of a composite blade and having at least one core wire.

In other aspects, embodiments of the invention relate to an energy dissipating member partially covered with a mold release agent and co-cured with a composite blade.

In other aspects, embodiments of the invention relate to an energy dissipating member having a damage initiator with at least one core wire coupled to the initiator. Further, the initiator may be a pouch. Still further, the bladder may have a plunger conforming to the bladder where the plunger works in conjunction with the at least one wick to expand the bladder and subsequently break or fracture the composite leaf.

In yet another aspect, embodiments of the present invention relate to a capsular bag that is activated upon separation of the release portion of the composite leaf from the composite leaf.

In yet another aspect, embodiments of the present invention relate to a method of manufacturing a frangible laminate, comprising the steps of: the method includes the steps of constructing a reinforced polymer matrix, cutting the reinforced polymer matrix into a plurality of laminae, forming a laminate via stacking the plurality of laminae and at least one energy dissipating member, and consolidating the laminate.

In another aspect, embodiments of the present invention relate to a method of reinforcing a polymer matrix with a resin, wherein the resin is selected from the group consisting of: polyetheretherketone, polyetherketoneketone, polyphenylene sulfide, polyamideimide, polyetherimide, epoxy, polyester, phenolic, vinyl ester, polyurethane, silicone, polyamide, and polyamideimide. Similarly, embodiments of the present invention relate to a method wherein the reinforced polymer matrix comprises a reinforcement, wherein the reinforcement is selected from the group consisting of: glass, graphite, polyaramid, and organic fibers. Additionally, embodiments of the present invention relate to methods wherein the resin further comprises a toughening material, wherein the toughening material is selected from the group consisting of elastomeric rubbers and thermoplastics.

In other aspects, embodiments of the invention relate to methods in which the laminae are plies, to methods in which the plies are formed into a final product, and to methods in which curing is performed in an autoclave.

In another aspect, embodiments of the present invention relate to a method in which a laminate is formed into a final product as a composite blade. In another aspect, embodiments of the present invention relate to a method of shaping a final product as a composite blade with a reinforced polymer matrix comprising a resin, wherein the resin is selected from the group consisting of: polyetheretherketone, polyetherketoneketone, polyphenylene sulfide, polyamideimide, polyetherimide, epoxy, polyester, phenolic, vinyl ester, polyurethane, silicone, polyamide, and polyamideimide. Similarly, embodiments of the present invention relate to a method of shaping a final product being a composite blade with a reinforced polymer matrix comprising a reinforcement, wherein the reinforcement is selected from the group consisting of: glass, graphite, polyaramid, and organic fibers.

In another aspect, embodiments of the present invention relate to a method of operating a self-shredding blade, the method comprising the steps of: releasing a released portion of a composite blade, the composite blade including at least one energy dissipating member; breaking the release portion via the at least one energy dissipating member; a retention portion that selectively retains the composite blade; and optionally breaking the retained portion via at least one energy dissipating member.

In another aspect, embodiments of the present invention relate to a method of operating a self-pulverizing blade in which an energy dissipating member is coupled to a rotor.

In another aspect, embodiments of the present invention relate to a method of operating a self-pulverizing blade, wherein the step of destroying further comprises destroying the composite blade structure surrounding the at least one energy dissipating member.

In another aspect, embodiments of the present invention relate to a method of operating a self-pulverizing blade, further comprising the step of altering the trajectory of the released portion via at least one energy dissipating member such that the released portion follows a predetermined path.

In yet another aspect, embodiments of the present invention relate to a method of operating a self-pulverizing blade, further comprising the step of dissipating kinetic energy of the released portion via at least one energy dissipating member.

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. All of the above summary features are understood to be examples only, and further features and objects of the structures and methods may be gleaned from the disclosure herein. A more complete appreciation of the features, details, utilities, and advantages of the present invention is provided in the following written description of various embodiments of the invention, illustrated in the accompanying drawings, and defined in the appended claims. Accordingly, non-limiting interpretation of this summary will be understood without further reading the entire specification, claims and drawings included herewith.

Drawings

The above-mentioned and other features and advantages of these embodiments, and the manner of attaining them, will become more apparent and the embodiments will be better understood by reference to the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side cross-sectional view of a ducted fan gas turbine engine;

FIG. 2 is a perspective view of an unducted, counter-rotating propeller engine mounted on an aircraft;

FIG. 3 is a side view of a counter-rotating propeller engine;

FIGS. 4, 5, 6 and 7 are respective timing elevation views of a ducted fan engine during release of the fan airfoil portion;

FIGS. 8 and 9 are side views of a composite blade with an energy dissipating member, the blade shown in an initial state and a separated state, respectively, and an exemplary embodiment of the present invention;

FIG. 10 is an alternative exemplary embodiment of the present invention and is a side view of a composite blade having an energy dissipating member including a failure initiator;

FIG. 11 is a perspective view of a damage initiator from the exemplary embodiment of the invention in FIG. 10.

Fig. 12 and 13 are cross-sectional cut-away views of the exemplary embodiment of the invention in fig. 10 and the damage initiator of fig. 11 in a "pre-accident" and "post-accident" condition, respectively.

FIG. 14 is a cross-sectional side view of another exemplary alternative embodiment of the present invention and of a composite blade having an energy dissipating member and a relief area;

FIG. 15 is a side view of another exemplary alternative embodiment of the present invention and of a composite blade having an energy dissipating member;

fig. 16, 17, 18 and 19 are respective timing front views of the propeller during release of the propeller portion after an impact event; and

fig. 20, 21, 22 and 23 are respective timing elevational views of the exemplary alternative embodiment of the invention of fig. 15 during a portion of the release following an impact event.

FIG. 24 is a flow chart summarizing the sequential processing steps performed by a method according to the present invention.

Detailed Description

It is to be understood that the described embodiments are not intended to limit the application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The described embodiments are capable of other embodiments and of being practiced or of being carried out in various ways. Each example is provided by way of illustration, and not by way of limitation, of the disclosed embodiments. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present embodiment without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms "connected," "coupled," and "mounted," and variations thereof herein, may be used broadly and encompass both direct and indirect connections, couplings, and mountings. In addition, the terms "connected" and "coupled" and variations thereof are not restricted to physical or mechanical connections or couplings.

As used herein, the terms "axial" or "axially" refer to a dimension along the longitudinal axis of the engine. The term "forward" used in conjunction with "axial" or "axially" refers to movement in a direction toward the engine inlet, or a component being relatively closer to the engine inlet than another component. The term "aft" used in conjunction with "axial" or "axially" refers to movement in a direction toward the engine nozzle, or a component being relatively closer to the engine nozzle than another component.

As used herein, the term "radial" or "radially" refers to a dimension extending between a central longitudinal axis of the engine and an outer periphery of the engine. Whether used alone or in combination with the terms "radial" or "radially," the use of the terms "proximal" or "proximally" refers to movement in a direction toward the central longitudinal axis, or a component being relatively closer to the central longitudinal axis than another component. Whether used alone or in combination with the terms "radial" or "radially," the use of the terms "distal" or "distally" refers to movement in a direction toward the outer periphery of the engine, or a component being relatively closer to the outer periphery of the engine than another component.

As used herein, the term "transverse" or "laterally" refers to a dimension perpendicular to both the axial and radial dimensions.

All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise) are only used for identification purposes to aid the reader's understanding of the present invention, and do not create limitations, particularly as to the position, orientation, or use of the invention. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. Thus, joinder references do not necessarily infer that two elements are directly connected to each other and in fixed relation. The exemplary drawings are for illustration purposes only and dimensions, positions, order and relative sizes reflected in the drawings may vary.

Fan blades for ducted fan gas turbine engines and propellers for single rotating turbine propellers and ductless counter rotating propeller gas turbine engines have some integrity against foreign object damage by birds, debris and other items ingested by the engine. However, the ingestion of foreign objects may cause the release of portions of the rotating blades or propellers, which may cause damage to other engine components or aircraft structures. In the case of fan blades or open rotors for single rotating turboprops and ductless counter-rotating propeller engines, the lack of ducting around the blades or propellers, if not otherwise managed, for these types of engines, provides the possibility for the trajectory of the released portion of the blade or propeller to hit that portion against the adjacent aft blades and other adjacent aircraft structures. The prior art blades and propellers do not have the fragility of reducing the size and energy of any released blade portion. Thus, shrouded single rotating turbine propellers and shrouded counter rotating fan blades and propellers that are resistant to foreign object damage but are fragile when desired can be provided.

The composite blade according to the invention is described in detail below. As used in the illustrations, this paragraph, and in the brief description that follows, the term "blade" is understood to include, but is not limited to, both fan blades and propellers, the term "composite" is understood to include, but is not limited to, reinforced polymer matrix composites, including matrices that are thermoset or thermoplastic and reinforcements that include, but are not limited to, glass, graphite, aramid, or organic fibers of any length, size, or orientation, and is further understood to include, but is not limited to, being manufactured by injection molding, resin transfer molding, prepreg tape lay-up (manual or automated), pultrusion, or any other suitable method for manufacturing reinforced polymer matrix composite structures. Additionally, "composite" is understood to include, but is not limited to, a hybrid composite of a reinforced polymer matrix composite in combination with a metal, a combination of more than one reinforced polymer matrix composite, or a combination of more than one metal. The term "co-curing" may be understood to include, but is not limited to, the act of curing the composite material and simultaneously bonding it to some other uncured material, as well as the act of curing two or more elements together, at least one of which may be fully cured and at least one may be uncured.

The term "trajectory" is understood to include, but is not limited to, the path taken by the released portion of the composite blade after the portion is released. The path may be, for example, depicted relative to a longitudinal centerline of the rotary machine, such as relative to a gas turbine engine centerline.

The composite blade may operate at high rotational speed and linear tip speed and may include at least one device selected from the group consisting of a device for dissipating energy, a device for self-shredding, and a device for predetermining a release trajectory. The composite blade may include one or more internal co-cured energy dissipating members capable of performing one of the functions selected from the group consisting of: dissipating the kinetic energy of the releasable portion of the blade, crushing the blade or the released portion of the blade, and changing the trajectory of the released portion of the blade. The energy dissipating member may be positioned inside the composite blade, or a portion of the energy dissipating member may extend outside of the composite blade and may extend radially from the base or root of the blade to the blade tip, and may be distributed along the axial chord of the blade. Additionally, some embodiments may include at least one curved portion in the energy dissipating member. The energy dissipating member may include a core wire or optional damage initiator to help pulverize the blades in the desired area and dissipate kinetic energy.

The term "self-pulverizing" is understood to include, but is not limited to, the ability of the composite blade to intentionally damage the composite blade itself after the blade impacts with sufficient force to release a portion of the composite blade, including the ability to break, tear, cut or expand the energy dissipating members of the surrounding composite blade structure, including, for example, a reinforced polymer matrix structure including a matrix that is either thermoset or thermoplastic, and reinforcements including, but not limited to, glass, graphite, aramid or organic fibers of any length, size or orientation. The comminution may occur sequentially or simultaneously at the same or different thicknesses, depths, chords or spans of the composite blade, which may result in the release of bands or fragments of the composite blade structure.

One exemplary, non-limiting embodiment of the composite blade utilizes an energy dissipating member having a core wire (strand) and a failure initiator (damage initiator) that are pulled through the structure of the composite blade after the composite blade impacts with sufficient force to release the portion, thereby breaking the composite blade structure. Other embodiments of the composite blade include relief regions along the radial span of the blade that work in conjunction with the energy dissipating member to balance impact resistance and fragility. Other embodiments include energy dissipating members having a core with slack or extra length staggered along the blade chord to align or alter the trajectory of the released portion to prevent impact with the trailing blade or other structure.

Referring initially to FIG. 1, a schematic side cross-sectional view of a ducted fan gas turbine engine 10 is shown including a fan module 12 and an engine core 14 positioned along an engine axis 32. Fan module 12 includes a fan casing 16 that surrounds a series of fan airfoils 18, with fan airfoils 18 extending radially distally from a rotor 20 and coupled to rotor 20. The engine core 14 includes a high pressure compressor 22, a combustor 24, and a high pressure turbine 26. The low pressure turbine 28 drives the fan airfoil 18. Alternatively, a speed reduction device 34 may be coupled between the low pressure turbine 28 and the rotor 20 to reduce the rotational speed of the fan module below the rotational speed of the low pressure turbine 28. The optional speed reduction device 34 may be a planetary gearbox of star or planetary construction, a compound gearbox, or other gear arrangement that effects a speed reduction between the low pressure turbine 28 and the rotor 20.

In operation, air enters through the air intake 30 of the engine 10 and moves through at least one compression stage where the air pressure may rise and be directed to the combustion chamber 24. The compressed air is mixed with fuel and combusted, providing hot combustion gases that exit the combustor 24 toward a high pressure turbine 26 and a low pressure turbine 28. At the high pressure turbine 26 and the low pressure turbine 28, energy is extracted from the hot combustion gases causing rotation of the turbine airfoils, which in turn rotate the shafts of the high pressure compression 22 and the fan airfoils 18, respectively, about the engine axis 32. With respect to the embodiments described herein, fan airfoil 18 represents the location of composite blade 40 within fan module 12 and ducted fan engine 10.

Referring now to FIG. 2, there is shown a perspective view of an unducted, counter-rotating propeller engine 110 mounted on the wing 102 of an aircraft 100. Additionally, in FIG. 3, a side view of the counter-rotating propeller engine 110 is shown including the engine axis 32, the cowling 114, and the fan module 116, the fan module 116 having two stages of counter-rotating propellers, a first stage 118 and a second stage 120. Each of the stages 118 and 120 has a plurality of propellers 122 and 124. Operation of the engine 110 is the same as discussed with respect to the ducted fan engine 10 of FIG. 1, with the fan module 116 having unshrouded propellers 122 and 124 that are not surrounded by a casing structure. Although not shown in fig. 2 or 3, the turboprop has only a single-stage propeller 118, nor a surrounding casing. With respect to the embodiments described herein, propellers 118 and 120 represent the position of composite blades within the fan module 116 of the counter-rotating propeller engine 110 and the turboprop engine with single-stage propeller 118. For clarity, in a total of three engine configurations as described above, the composite blades will rotate about respective engine axes 32.

Referring to FIG. 1, foreign objects, such as, but not limited to, birds, channeled through inlet 30 and drawn into fan module 12 may cause damage to fan airfoils 18, fan casing 16, and other downstream structures in engine 10. Similarly, for counter-rotating propeller engine 110, as shown in FIG. 3, foreign objects may be located in the path of fan module 116 during engine operation, causing damage to the unducted propellers 122 and 124. Damage to the fan airfoil or propeller can be particularly troublesome because these components are relatively large in diameter and length when compared to the engine core 14 diameter and the size of potential foreign objects, such as birds or airport debris, that may impact the fan airfoil or propeller. This large size allows for partial release of the fan airfoil or propeller and causes secondary collisions and subsequent damage. Such damage may cause a reduction in engine performance and, in some cases, a loss of engine power.

Fig. 4, 5, 6, and 7 depict time phase images of events inside fan module 12 that may be spread out after fan airfoil 18 collides with a foreign object that causes the release of fan airfoil 18. This front view of ducted fan engine 10 uses conventional stages of fan airfoils 18 and fan case 16. Referring now to fig. 4, 5, 6, and 7, each figure shows twenty fan airfoils 18 and fan casing 16 and shows the timing of engine 10 during partial airfoil 18 release, twenty being merely an exemplary number of airfoils 18 and not intended to limit the present invention in any way. One of the airfoils 18 in each of fig. 4-7 is labeled with the letter R, which is indicated as a release airfoil or airfoil 18 that may be initially impacted by a foreign object and then potentially cause a portion of the airfoil 18 to release. The other airfoil 18 adjacent to the released airfoil R has been identified with the letter T, which is labeled as the aft airfoil. The aft airfoil T is an airfoil 18 that tracks or lags the airfoil 18. Identifying the particular airfoil 18 as a release blade and an aft blade is exemplary and not limiting of the invention in any way. In FIG. 4, all of the fan airfoils 18 are in a raw state, which have not been impacted by a foreign object. In fig. 5, the release airfoil R has been impacted by a foreign object and may now separate into two pieces. Turning to FIG. 6, the free portion of the release airfoil R is likely to collide with the trailing airfoil T. Finally, in fig. 7, the aft airfoil T is separated into two pieces due to the collision of the free portion of the release airfoil R, which is removed for clarity.

Due to the high rotational speed of the fan airfoils 18 in the engine 10, any reduction in the size of the free portions of the discharge airfoils reduces the kinetic energy that the aft airfoils T and the fan casing 16 need to withstand. This reduction in required energy absorption results in a reduction in the relative weight of the fan housing 16 as it allows for the elimination of the contained devices and structures within the housing 16. Reducing weight allows the aircraft to carry more fuel for longer voyages or increased solidity by allowing weight in another area of engine 10 to be increased. Another important benefit from reducing the size of the free portion is the parallel reduction of the unbalanced load experienced by the rotor 20 due to the eccentricity caused by the release of the inertial load and the variation of the fan blades 18 loaded on the rotor 20 after release. These benefits may also be welcomed when considering the open rotor engine 110 and any reduction in the size of the released portions of the propellers 122 and 124.

As shown in the exemplary embodiments of the present invention in fig. 8 and 9, this objective may be achieved by incorporating one or more energy dissipating members 80 into the composite blade 40. Considering first FIG. 8, a composite blade 40 is shown in an initial state having a root 42, a tip 44, a leading edge 46, and a trailing edge 48, with a span 52 of the blade 40 radially distal from the root 42 to the tip 44, and an axial chord 54 moving aft from the leading edge 46 to the trailing edge 48. The internal flowpath 50 may be defined in the span radially distal from the root 42 along a chord 54 and represents the lowest radial portion of the span 52 that will be subject to a foreign object collision event. In the exemplary embodiment, composite blade 40 has three energy dissipating members 80, energy dissipating members 80 having cores 82 of various lengths, each energy dissipating member 80 selectively beginning in root 42 and extending radially distally toward tip 44 and then curving back radially and proximally toward inner flow path 50, forming at least one selectively curved portion 86. Although the energy dissipating member 80 in this embodiment begins at the root 43, the member 80 may begin at any location in the composite blade 40, e.g., tip, mid-span, etc. Coupled to both ends of each core wire 82 may be at least one damage initiator 84 defined in the structure described above. In this embodiment, the provision of a separate energy dissipating member 80 is selected to include an end located radially below the inner flow path 50 that extends through the inner flow path 50 radially above the inner flow path 50, but is not limited to such provision and arrangement of the member 80. Three energy dissipating members 80 are shown in this exemplary embodiment, but any number of members 80 may be employed.

Non-limiting examples of energy dissipating members may include a core wire that may be located inside, may extend partially to the outside, and may be co-cured with the composite blade. The core material may include, but is not limited to, Toyobo corporation's registered trademark(poly (p-phenylene-2, 6-benzodioxazole)) fibers, high strength metal wires or any other suitable high strength material in the form of a core wire. Exemplary, non-limiting embodiments of the cross-sectional shape of the core wire can be circular, oval, polygonal, or irregular, and can have cross-sectional dimensions in the range of from about 0.005 inch to about 0.075 inch and from about 0.010 inch to about 0.030 inch. Other exemplary, non-limiting embodiments of the cross-sectional area of the core wire can be from about 0.0001 square inches to about 0.02 square inches and from about 0.001 square inchesA cross-sectional area in the range of about 0.002 square inches. Other exemplary non-limiting core wire forms may include braid, fabric, tape or ribbon forms. The core segment may be constant along the length or vary in its cross-sectional size, cross-sectional shape, form and material, including but not limited to increasing in size from one end of the length to the other.

Exemplary shapes and material aspects of the damage initiator may be tailored to the profile of the composite blade in localized areas, and furthermore the material selection may be tailored to not chemically react with the composite blade during co-curing, assembly, or composite blade operation. Non-limiting examples of damage initiators may include formed, solid, hollow or saw-tooth wedge shaped metal, ceramic or composite structures, which are not shown for ease of understanding purposes, and may also be internal and co-cured with the composite blade. Such damage-inducing device materials may include, but are not limited to, steel, aluminum, titanium, cobalt, chromium, and nickel metal alloys, or any other suitable metal alloy. Other damage initiator materials may include, but are not limited to, ceramic oxides including beryllium oxide, cerium oxide, and zirconium oxide; non-oxides including carbides, borides, nitrides, and silicides; and oxides and non-oxides, alone or in combination, with or without particulate or fibrous reinforcement. Another non-limiting embodiment of a damage initiator includes an at least partially hollow pouch at least partially filled with a filler. The form of the filler may include, but is not limited to, a fluid or a semi-solid. The fluid and semi-solid materials may include, but are not limited to, silicone, gels, caulking or other incompressible or nearly incompressible materials, or combinations of these materials suitable for composite fabrication. The bladder may contain a plunger that works in conjunction with the core and may expand the bladder by pressing in to alter the contents of the bladder as the core is tensioned, thereby inducing comminution in the area of the composite leaves surrounding the bladder. Alternatively, the filling may also be a small solid metal or ceramic piece, alone or in combination with the fluid and semi-solid fillings described above. Another exemplary non-limiting mode of comminution, after the composite blade impacts with sufficient force to release a portion of the blade, utilizes an energy dissipating member having a core wire and a bladder, the core wire being pulled through the structure of the composite blade, activating the bladder and expanding the bladder, thereby comminuting the composite blade structure.

The energy dissipating member, including non-limiting examples of core wires and damage initiators, may be at least partially covered with a release agent, film, or coating to help the member dissipate energy by facilitating the initial sliding or movement of the member within the composite blade. The release agent may include, but is not limited to, Henkel's registered trademarkRegistered trademark of EUROCO AT, DuPont(polytetrafluoroethylene) or other suitable release agents for making composite materials.

Any combination of composite blade elements, including but not limited to energy dissipating members, cords, and damage initiators, including all variations in the location, materials, fabrication, shape, size, cross-sectional properties, and length properties of any element, may be suitable for energy dissipation, comminution, and trajectory alignment. The invention also relates to a method for manufacturing a composite blade. In addition, the present invention relates to the assembly of fragile or composite blades into rotary machines and for use in rotary machines. The method may utilize any combination of composite blade elements as described above.

Turning now to fig. 9, the exemplary embodiment of fig. 8 is shown in a separated state, similar to that described above in fig. 4-7 with reference to the releasing blade R and the trailing blade T after being impacted by a foreign object or a free portion of the releasing blade, respectively. As shown, the core wire 82 may be tensioned or stretched when the composite blade may collide. This strain applied to the cords extracts kinetic energy from the relieved portion, and the composite blade 40 reduces the impact energy that an adjacent composite blade 40 or fan casing 16 will experience and need to withstand. Along with the strain applied to the core wire 82, the released portion of the composite blade 40 drags the co-cured core wire 82 through the internal structure of the composite blade 40, again reducing the kinetic energy of the released portion and simultaneously crushing the retained and released portions of the blade 40. The optional break initiator 84 helps break up the released portion and can break up the larger portion into two or more portions with a lower individual kinetic energy.

FIG. 10 is another exemplary embodiment of a composite blade 40, again having a root 42, a tip 44, a leading edge 46, and a trailing edge 48, with a span 52 of the blade 40 radially distal from the root 42 to the tip 44, and an axial chord 54 aft from the leading edge 46 to the trailing edge 48. Again, the internal flowpath 50 may be defined in span radially above the root 42 along the chord 54 and represents the lowest radial portion of the span 52 that will be subject to a foreign object collision event. In the exemplary embodiment, composite blade 40 has five energy dissipating members 80. Each energy dissipating member 80 has at least one core wire 82, at least a portion of the core wire 82 being located outside of the composite blade 40. The radially proximal end of the core wire 82 is coupled to the rotor 20, and then a length of the core wire 82 is advanced radially distally to pass through the root 42, through the internal flow path 50, and into the span 52, where the core wire 82 may be coupled at its radially distal end to a damage initiator 84, in this exemplary embodiment of the damage initiator 84. Five energy dissipating members 80 are shown in this exemplary embodiment, but any number of members 80 may be employed.

An exemplary damage initiator 84 as illustrated in the composite blade 40 of FIG. 10 is shown in FIG. 11. The example damage initiator 84 has a bladder 90, a plunger 92, and may be at least partially filled with a filler 94. The shape and size of the bladder 90 may be adapted to have any suitable size, shape and configuration to conform to the local contour and size of the composite blade 40 in the area in which it is disposed, the illustrated configuration being for exemplary purposes only. The core wire 82 may pass through the bladder 90 and may be coupled to the plunger 92. At least a portion of the energy dissipating member 80 may be coated with a release agent 96. In this exemplary embodiment, at least a portion of the exterior of the pouch 90 and core wire 82 may be covered with a release agent 96 to facilitate initiation of separation and comminution. The periphery of the plunger 92 may be adapted to conform to the bladder 90 in a "pre-accident" position where the blade 40 has not yet impacted the foreign object damage to the extent that the energy dissipating member 80 has been activated.

Fig. 12, which is a cross-sectional view of fig. 10, depicts the bladder 90, plunger 92 and core wire 82 in a pre-accident position. In the event that the composite blade 40 may be impacted by a foreign object, the energy imparted on the composite blade 40 may cause the release of a portion of the blade 40. If this happens, the wick 82 and plunger 92 may be activated. This activation may occur when the released portions of the blades 40 are separated at a location that may be coupled to the radially proximal portion of the rotor 20 radially proximal to the damage initiator 84 and radially distal from the associated core wire 82. Upon impact with a force that may cause the blades 40 to separate, the released portions of the blades 40 may move radially away from the rotor 20. However, the end of the associated core wire 82 that may be coupled to the rotor 20 may not move with the released blade portion, which may cause relative movement between the end of the core wire 82 coupled to the rotor 20 and the released portion of the blade 40, which may include a radially distal end of the core wire 82 that may be coupled to the damage initiator 84. This relative movement may cause the core-wire 82 coupled to the damage initiator 84 to be drawn substantially radially proximally into a "post-accident" position, as shown in the cross-sectional view of FIG. 10, FIG. 13.

When the plunger 92 is pulled into the post-accident position, the plunger 92 may compress any filler 94 in the bladder 90. Since the periphery of the plunger 92 may conform to the bladder 90, the bladder may be filled with an incompressible filler 94, and the force exerted on the filler 94 by the plunger 92 is transmitted into the bladder 90, thereby expanding the bladder 90. While the bladder 90 may be contained within the composite blade 40, this expansion also expands the composite blade 40. Further, with the selective assistance of the release agent 96, a separation region may be formed in the composite blade adjacent to the damage initiator 84. The expansion and separation region of the composite blade 40 may thereby break up and weaken the blade 40. Comminution may take the form of delamination of the composite structure, broken fibers, broken matrices, and the like. This reduces the number of load bearing composite structures and thereby reduces the strength of the composite material at and around the shredding location. During operation, since the composite blade is under high centrifugal loads, this reduction in strength may lead to further damage to the composite blade 40 by distributing the load over a smaller cross-section of the blade 40. This may ultimately result in separation and release of additional portions of the blade 40.

This weakening or crushing of the composite blade 40 may be repeated by each activated energy dissipating member 80 in the composite blade 40. By staggering the axial and radial positions of the energy dissipating members 80 in the composite blade 40, a sequencing and combination of pulverization can be produced. This may be accomplished by placing energy absorbing members at varying thicknesses in the composite blade cross-section and by varying the size and shape of the failure initiator 84 to accommodate local geometric differences at these thicknesses and locations. Further, within the energy dissipating member 80, one or more damage initiators 84 may be used and may be distributed in series along the core wire 82. Additionally, within the energy dissipating member 80, the core wire 82 may have slack or additional length between the serially disposed damage initiators 84, the slack may crush the composite blade 40 as the core wire 82 is pulled through the composite blade 40, and may delay activation of the serially disposed damage initiators 84. Five energy dissipating members 80 are shown in this exemplary embodiment, but any number of members 80 may be employed.

Referring now to FIG. 14, a cross-sectional side view of another exemplary embodiment of a composite blade 40, again having a root 42, a tip 44, a leading edge 46, and a trailing edge 48, with a span 52 of the blade 40 radially distal from the root 42 to the tip 44, and an axial chord 54 aft from the leading edge 46 to the trailing edge 48. Again, the internal flowpath 50 may be defined in span radially above the root 42 along the chord 54 and represents the lowest radial portion of the span 52 that will be subject to a foreign object collision event.

In the exemplary embodiment of FIG. 14, the span 52 of the composite blade 40 may be radially divided into three relief regions, a low-span region 60, a mid-span region 62, and a high-span region 64. There may be one or more cavities within each relief area, identified for exemplary purposes only in size, shape, configuration and positioning as 60A, 60B, 60C for the low-span area 60, 62A and 62B for the middle area 62, and 64A and 64B for the high-span area 64, as illustrated. These cavities may be devoid of filler or alternatively filled with resin, foam, loose media, or the like. The radially proximal ribs of cavities 60C, 62B and 64B include one or more flanges 66 that mate with channels 68 connecting adjacent cavities. Similarly, cavities 62A and 64A include passages 68 connecting adjacent cavities. Three energy dissipating members 80 may be located inside the composite blade 40 and co-cured with the composite blade 40 and extend radially from the root 42 to the tip 44, through the channel 68 and flange 66 and may be axially distributed along the chord 54 without overlapping. An optional damage initiator can be coupled to the core wire at the flange 66 and within the nesting interior of the flange 66.

The relief area cavity acts in conjunction with the energy dissipating member and damage initiator, seeking to balance the impact resistance and fragility of the blade along the radial span of the blade. When a foreign object impacts the composite blade 40 at the high span region 64 in the area of the cavity 64A with sufficient energy to separate the entire high span region 64 portion of the composite blade 40, the energy dissipating members 80 passing through the flanges 66 and the channels 68 of the cavity 64B will be tensioned, as illustrated in FIG. 9, reducing the kinetic energy of the released portion. The damage initiator nested inside the flange 66 will also be pulled through the flange 66 and the channel 68 and break the released portion into more than one segment or portion, each with a lower individual kinetic energy. However, for the present example, the other two energy dissipating members 80 may not be tensioned because they may be radially close to the released (entire high-span region 64) portion of the composite blade 40 and thus do not reduce the integrity of the low-span region 60 and the mid-span region 63 to the impact. The radial distribution of the relief area cavities in combination with the plurality of energy dissipating members provides fragility in areas radially away from the impact area, but maintains impact resistance in areas proximate to the impact area. Three energy dissipating members 80 are shown in this exemplary embodiment, but any number of members 80 may be employed. Similarly, three span regions and seven cavities are shown, but any number of regions, cavities, flanges and channels may be employed.

Turning now to FIG. 15, a side view of another exemplary embodiment of a composite blade 40, also having a root 42, a tip 44, a leading edge 46, and a trailing edge 48, has a span 52 of the blade 40 radially distal from the root 42 to the tip 44, and an axial chord 54 passing from the leading edge 46 to the trailing edge 48. Again, the internal flowpath 50 may be defined in span radially above the root 42 along the chord 54 and represents the lowest radial portion of the span 52 that will be subject to a foreign object collision event. The composite blade 40 has a single energy dissipating member 80 extending radially from the root 42 to the tip 44 in a staggered fashion from the leading edge 46 to the trailing edge 48 without overlapping. Additional exemplary staggered forms for the energy dissipating members 80 may begin at the rotor 20 or blade root 42, extend radially distally along the span 52, traverse the chord 54 to the blade tip 44 in a helical path, and vary in depth through the thickness of the blade 40. Additional exemplary staggering patterns for the energy dissipating members 80 may be irregularly staggered along the span and chord of the blade 40, and may form at least one optional bend 86 as the energy dissipating members 80 may extend radially distally from the root 42 or rotor 20 to the tip 44. The example energy dissipating member 80 may be located inside the composite blade 40 and co-cured with the composite blade 40. An embodiment of the energy dissipating member 80 may be a core wire as described above in the exemplary embodiment in fig. 8. In the present embodiment, the staggered form may provide slack or additional length to the member 80 as compared to a shorter length that would extend directly from the root 42 to the tip 44. When a foreign object breach impacts composite blade 40, the portion of blade 40 that may be released will pull member 80 radially and proximally from the released portion, reducing the kinetic energy of the released portion. Additionally, the placement and staggering of the energy dissipating members 80 may vary the trajectory of the released portion of the composite blade 40, as described below. A single energy dissipating member 80 is shown in the exemplary embodiment, but any number of members 80 may be employed.

Referring to the aircraft 100 in FIG. 2, having a counter-rotating propeller gas turbine engine 110, also referred to as an open rotor, mounted on the aircraft 100, if a portion of the propeller is released from the fan module 116, there may be a possibility that the portion of the propeller may impact the aircraft fuselage. As described above, the placement and staggering of the energy dissipating members within the composite blade 40 will adjust the trajectory of the released portion of the composite blade 40. This improvement may be advantageous because it may be desirable to direct the released portion away from the adjacent composite blade 40 or aircraft structure potentially including the aircraft fuselage.

Fig. 16 to 19 and fig. 20 to 23 depict this trajectory improvement. The figures utilize a reference blade timing (FIGS. 16-19) and a separate timing (FIGS. 20-23) depicting an exemplary embodiment of a composite blade 40 having a modified trajectory. As with the timing sequence detailed in fig. 4-7, one of the airfoils in each of fig. 16-19 is identified with the letter R, which is identified as the release airfoil, and the other is identified with the letter T, which is identified as the aft airfoil. The sequence begins with FIG. 16 depicting the release airfoil and the aft airfoil in an initial state just after a collision with a foreign object. Next, in fig. 17, a portion of the release airfoil may be moved toward the aft airfoil, the radial proximal end of the portion rotating toward the aft airfoil having not yet affected the aft airfoil. Then in fig. 18, the radially proximal end of the released portion may hit the aft airfoil, distorting the shape of the aft airfoil, although any other portion of the released airfoil may hit the aft airfoil. Finally, in fig. 19, the released portion of the released airfoil continues to collide and further distort the aft airfoil. Depending on the kinetic energy of the released portion of the release airfoil and the contact location on the aft airfoil, this distortion may cause damage to the aft airfoil.

In contrast, as shown in fig. 20-23, the exemplary embodiment of the composite blade 40 from fig. 15 is in a position with the released blade, again labeled R, and the adjacent trailing blade, similarly labeled T, repeating the sequence. The sequence starts again with fig. 20 depicting the release blade just after impact with a foreign object and the trailing blade in the initial state. However, in fig. 20, the released portion of the release blade is constrained to the retained portion of the release blade by the energy dissipating member 80. Next, in fig. 21, the released portion of the release blade moves toward the trailing blade when the radially proximal portion of the portion is constrained to the retained portion by the energy dissipating member 80. In fig. 21, the energy dissipating members 80 as described above have a staggered form that provides slack or extra length in the composite blade 40. As the kinetic energy of the released portion moves the portion radially distal from the retained portion, the slack in the energy dissipating member 80 may be pulled through the released portion in a preferred direction relative to the trajectory of the aligned released portion while reducing the kinetic energy of the released portion. As the released portion continues to move radially distally, the slack in the energy dissipating member 80 may be reduced with the released portion remaining aligned with the retained portion, as shown in fig. 22. Finally, as shown in fig. 23, when the slack in the energy dissipating member 80 is consumed, the member 80 may break, with the released portion continuing on the alignment path, reducing the kinetic energy of the released portion and avoiding the trailing blades. This same principle can be used to limit the released portion to preferentially align with the released portion primarily aft, away from the aircraft 100 and nearby aircraft structures.

The above-described exemplary embodiments of the composite blades 40 may be used in rotary machines including, but not limited to, ducted fans, open rotors, turboprop gas turbine engines, and shore-based gas turbines, with the number of blades 40 ranging from, but not limited to, about 2 to about 24, from about 8 to about 16, and additionally from about 10 to about 14. The span 52 of these exemplary embodiments of the composite blade 40 may range from including, but not limited to, about 20 inches to about 90 inches, from about 40 inches to about 70 inches, and from about 50 inches to about 70 inches. The chord 54 of these exemplary embodiments of the composite blade 40 may be in a range including, but not limited to, about 5 inches to about 40 inches, from about 10 inches to about 30 inches, and from about 12 inches to about 24 inches.

FIG. 24 illustrates one non-limiting example process 500 for manufacturing a brittle laminate, which may be a composite blade 40. The process 500 may include a substantially unidirectional pre-impregnation (prepreg) process of constructing a reinforced polymer matrix from resin and reinforcement material 502. The reinforcing material may take the form of fibers, rovings, mats, woven rovings, woven yarns, braids, or stitch-bonded fabrics. The resin is provided as a liquid at room temperature or can be heated to a liquid state. The reinforcing material is then impregnated with a resin to form a reinforced polymer matrix. Impregnation, also known as sizing, can be achieved by spraying, dipping, bonding or similarly depositing the resin in one or more layers or sizing steps on the reinforcing material. A non-limiting example is carbon fiber as a unidirectional reinforcing material impregnated with epoxy resin. Other exemplary non-limiting resins include Polyetheretherketone (PEEK), Polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), Polyamideimide (PAI), and Polyetherimide (PEI), as well as polyesters, phenolics, vinyl esters, polyurethanes, silicones, polyamides, polyamideimides, and the like. Some of these resins may be toughened by incorporating dispersed elastomers such as elastomeric rubbers or thermoplastic materials dispersed in the resins, etc.

In the exemplary non-limiting process 500, a lay-up process may then be performed. The placement process includes cutting the reinforced polymer matrix into a plurality of thin layers 504. As used in this specification, the term lamina refers to plies, ply segments and portions of plies that are complete in shape and strip. The laminae and at least one energy dissipating member 80 are stacked to create a laminate 506. One or more energy dissipating members 80 may be disposed at varying locations in the laminate, and may be located inside or partially outside the laminate, as shown in the exemplary embodiment of a composite blade in FIG. 10. The process may also include an ultrasonically assisted stitching process, wherein reinforcing fibers may be inserted through the plies, improving the quality of the laminate as a whole. The lamination process may also include shaping the lamina prior to and during stacking the lamina and the energy dissipating member 80. The machine lay-up process can save labor costs when compared to conventional lay-up processes that utilize manual dexterity and labor to cut plies and to construct and shape laminae.

Finally, the process may utilize a consolidation process to shape and cure the plies to produce composite blade 508. The consolidation process utilizes consolidation forces to press the plies and their laminae into the desired shape and may be part of the lamination process and may be performed in situ. One non-limiting example is an autoclave process that places the laminate in a high pressure apparatus to shape and cure the laminate. Suitable autoclave temperatures include temperatures from about 400F to about 840F, preferably from about 600F to about 760F.

This written description uses examples to disclose the invention, including the preferred embodiment, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. 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 languages of the claims. Aspects of the various embodiments described, as well as other known equivalents for each of these aspects, can be combined and matched by one of ordinary skill in this art to construct additional embodiments and techniques in accordance with principles of this application.

Claims (30)

1. An airfoil, comprising:

a composite blade (40), the composite blade (40) having a root (42), a tip (44), and a span (52) therebetween, a leading edge (46), a trailing edge (48), and a chord (54) therebetween, and at least one energy dissipating member (80) comprising at least one pocket (90).

2. The airfoil of claim 1, wherein the at least one energy dissipating member (80) extends along the span (52) and is distributed along the chord (54), the at least one energy dissipating member (80) including at least one core wire (82).

3. The airfoil of claim 1, wherein the at least one energy dissipating member (80) is at least partially covered with a mold release agent (96).

4. The airfoil of claim 1, wherein the at least one energy dissipating member (80) is at least partially co-cured with the composite blade (40).

5. The airfoil of claim 2, wherein the at least one energy dissipating member (80) further comprises at least one damage initiator (84), wherein the at least one core wire (82) is coupled to the at least one damage initiator (84).

6. The airfoil of claim 5, wherein the at least one damage initiator (84) comprises the at least one pocket (90).

7. The airfoil of claim 6, wherein the at least one damage initiator (84) comprises at least one plunger (92) adapted to conform to the at least one pocket (90).

8. The airfoil of claim 7, wherein the at least one plunger (92) is coupled to the at least one core wire (82), the at least one bladder (90) being at least partially filled with a filler (94).

9. The airfoil of claim 8, wherein the at least one plunger (92) works in conjunction with the at least one wick (82) to expand the bladder (90) thereby pulverizing the composite blades (40).

10. The airfoil of claim 1, wherein the pocket (90) is activated when the released portion of the composite blade (40) is separated from the composite blade (40).

11. A method (500) of manufacturing a frangible laminate, the method comprising the steps of:

constructing a reinforced polymer matrix (502),

cutting the reinforced polymer matrix into a plurality of thin layers (504),

forming a laminate (506) by stacking the plurality of laminas and at least one energy dissipating member,

and consolidating the plies (508).

12. The method of claim 11, wherein the reinforced polymer matrix comprises a resin, wherein the resin is selected from the group consisting of: polyetheretherketone, polyetherketoneketone, polyphenylene sulfide, polyamideimide, polyetherimide, epoxy, polyester, phenolic, vinyl ester, polyurethane, silicone, polyamide, and polyamideimide.

13. The method of claim 11, wherein the reinforced polymer matrix comprises a reinforcement, wherein the reinforcement is selected from the group consisting of: glass, graphite, polyaramid, and organic fibers.

14. The method of claim 11, wherein the plurality of laminae comprises a plurality of laminae.

15. The method of claim 11, further comprising shaping the laminate into a final product.

16. The method of claim 11, wherein consolidating the plies further comprises consolidating the plies in an autoclave.

17. The method of claim 11, wherein the laminate includes a blade (18).

18. The method of claim 12, wherein the resin further comprises a toughening material, wherein the toughening material is selected from the group consisting of elastomeric rubbers and thermoplastics.

19. The method of claim 17, wherein the reinforced polymer matrix comprises a resin, wherein the resin is selected from the group consisting of: polyetheretherketone, polyetherketoneketone, polyphenylene sulfide, polyamideimide, polyetherimide, epoxy, polyester, phenolic, vinyl ester, polyurethane, silicone, polyamide, and polyamideimide.

20. The method of claim 17, wherein the reinforced polymer matrix comprises a reinforcement, wherein the reinforcement is selected from the group consisting of: glass, graphite, polyaramid, and organic fibers.

21. A method of operating a self-shredding blade, the method comprising the steps of:

releasing a released portion of a composite blade (40), the composite blade (40) including at least one energy dissipating member (80);

breaking the release portion via the at least one energy dissipating member (80);

selectively retaining a retained portion of the composite blade (40); and

selectively breaking the retained portion via the at least one energy dissipating member (80).

22. The method of claim 21, wherein the at least one energy dissipating member (80) further comprises at least one core wire (82).

23. The method of claim 21, wherein the at least one energy dissipating member (80) further comprises at least one damage initiator (84).

24. The method of claim 21, wherein the at least one energy dissipating member (80) is at least partially covered with a release agent (96) and at least partially co-cured with the composite blade (40).

25. The method of claim 23, wherein the at least one damage initiator (84) comprises at least one pouch (90).

26. The method of claim 25, wherein the at least one energy dissipating member (80) further comprises at least one core wire (82); and the at least one damage initiator (84) comprises at least one plunger (92) adapted to conform to the at least one balloon (90), wherein the at least one plunger (92) is coupled to the at least one core wire (82), the at least one balloon (90) being at least partially filled with a filler (94).

27. The method of claim 21, wherein at least one of the at least one energy dissipating member (80) is coupled to a rotor (20).

28. The method of claim 21, wherein the step of destroying further comprises destroying a composite blade structure surrounding the at least one energy dissipating member (80).

29. The method of claim 21, further comprising the step of altering the trajectory of the released portion via the at least one energy dissipating member (80) such that the released portion follows a predetermined path.

30. The method of claim 21, further comprising the step of dissipating kinetic energy of the released portion via the at least one energy dissipating member (80).