Blades comprising composite materials and related manufacturing methods

Abstract

The present invention relates to a blade (7), comprising: a composite material structure (17); a blade root fastening portion (9), the blade root fastening portion further comprising a shoulder (10), the shoulder extending from the wall into a recess; a base (18), which is arranged in the recess and comprises: a support member, the support member being configured to abut against the shoulder (10) of the blade root fastening portion (9); and a channel (39), which is formed in the support member and through which a section (23) of the blade root portion (22) of the composite material structure extends; and a locking component (19), which is arranged in the recess and is located between two sections (23) of the blade root portion (22), so that each section of the blade root portion (23) is pressed against the support member by the locking component (19).

Description

Technical Field

[0001] The invention relates to a blade comprising a composite material structure.

[0002] More particularly, but not exclusively, the present invention relates to a blade intended for an aircraft engine (such as an open rotor type engine whose fan is unducted and has two rotating propellers; or an unducted rotor type engine having an unducted single fan (USF) with a movable blade set and a fixed blade set; or a turboprop with a single propeller architecture) or a wind turbine rotor. Background Art

[0003] The benefit of an unducted fan engine is that the diameter of the fan is not limited by the presence of a fairing, so an engine with a high bypass ratio can be designed, thereby reducing fuel consumption.

[0004] Therefore, in this type of engine, the fan blades can have a very large span.

[0005] Furthermore, these engines generally include a mechanism for adjusting the pitch angle of the blades in order to adapt the thrust generated by the fan to the different phases of flight.

[0006] However, the design of such blades needs to take into account the opposing stresses.

[0007] On the one hand, the dimensions of these blades must allow for optimal aerodynamic performance (maximizing efficiency and providing thrust while minimizing losses). An improvement in the aerodynamic performance of the fan tends to increase the bypass ratio (BPR), which is expressed as an increase in the external diameter and thus an increase in the span of the blades.

[0008] On the other hand, it is also necessary to guarantee resistance to the mechanical stresses that may be exerted on these blades while also limiting their acoustic characteristics.

[0009] Furthermore, on unducted fan turbomachine architectures, engine startup is typically performed at a very open pitch angle, specifically, a very open pitch angle for dissipating power via torque, which ensures machine safety while maintaining a low fan power rating.

[0010] However, at very open pitch angles, the blades experience a completely separated turbulent aerodynamic flow, which produces broadband vibration excitation. In particular, on blades with a wide chord and a large span, the bending forces are strong, even though the engine power rating is not maximum.

[0011] In normal operation, the pitch is varied (the pitch angle is narrower) during ground and flight phases. As a result, the aerodynamic flow is perfectly sound (reattached to the aerodynamic profile). Broadband stress is eliminated, the rotational power rating is higher, and bending forces are controlled.

[0012] Currently, these blades are typically made of metal. While metal blades have good mechanical strength, they do have the disadvantage of being relatively heavy.

[0013] To reduce this mass, it would be desirable to manufacture the blades from composite materials. However, the intense aerodynamic forces to which the blades are subjected could damage the blades and / or the hub in the interface region between the blades and the fan rotor hub. This problem is particularly acute when the blades are connected to the hub by pinned fasteners due to the vibration levels commanded by 1N, 2N, and 3N engines. Summary of the Invention

[0014] One object of the present invention is to propose a blade comprising composite material suitable for use with a variable pitch mechanism and in an open rotor type environment, while being able to resist strong aerodynamic forces within the constraints of limited volume and minimum mass.

[0015] To this end, according to a first aspect of the present invention, there is provided a blade, the blade comprising:

[0016] a composite material structure comprising a fiber reinforcement obtained by three-dimensional weaving and a matrix embedded in the fiber reinforcement, the composite material structure comprising a blade part having an aerodynamic profile and a blade root part comprising two parts, each part being connected to the blade part;

[0017] a blade root fastening member comprising a wall defining a cavity and an opening formed in the wall, the composite structure extending through the opening such that the blade component is located outside the fastening member and the blade root component is located inside the cavity, the blade root fastening member further comprising a shoulder extending from the wall into the cavity;

[0018] a base arranged in the cavity, the base comprising: a support configured to abut against a shoulder of the blade root fastening part; and a channel formed in the support through which a portion of the blade root part of the composite material structure extends; and

[0019] - a locking member arranged in the cavity and located between the two parts of the blade root part, so that each part of the blade root part is then pressed against the support by the locking member.

[0020] The following are some preferred but non-limiting features of the blade according to the first aspect, used alone or in combination:

[0021] - The blade further comprises an expanding foam arranged in the cavity between the base and the opening.

[0022] - The end of each portion of the blade root member is folded under the locking member or placed against the lower face of the base.

[0023] The blade further comprises a cover body resting on the end of the portion of the blade root member and configured to be attached to the fastening member in order to lock said portion and the locking member.

[0024] - A fiber reinforcement comprising a blade fiber reinforcement portion and two blade root fiber reinforcement portions, wherein the blade root fiber reinforcement portions are each woven continuously with the blade fiber reinforcement portion, the two blade root fiber reinforcement portions being separated by a loosened area obtained during the three-dimensional weaving of the fiber reinforcement.

[0025] The sides of the support delimiting the channel are inclined so that the channel diverges in the direction of the second opening of the fastening part, which is situated below the blade root part, on the side opposite to the fastening part with respect to the opening.

[0026] According to a second aspect, the present invention provides a method for manufacturing a blade according to the first aspect, the method being based on a fiber reinforcement obtained by three-dimensional weaving, the fiber reinforcement comprising a blade fiber reinforcement portion and two blade root fiber reinforcement portions, the method comprising the following steps:

[0027] S2: Producing blade root fastening components to form the cavity and shoulder;

[0028] S3: Place the base in the fastening component against the shoulder;

[0029] S4: placing the fiber reinforcement into the blade root fastening component through the opening, so that the blade fiber reinforcement portion is located outside the fastening component and the two blade root fiber reinforcement portions are located inside the cavity;

[0030] S5: inserting the locking component into the cavity and between the two blade root reinforcement parts, so that each part of the blade root part is then pressed against the support by the locking component;

[0031] S9: placing the fiber reinforcement, the fastening component, the base, and the locking component in the mold;

[0032] S10: Injecting plastic into the mold to form a composite material structure including a fiber reinforcement and a matrix embedded in the fiber reinforcement.

[0033] The following are some preferred but non-limiting features of the method according to the second aspect, used alone or in combination:

[0034] - The method further comprises, before the step S10 of injecting the plastic, a step S7 of injecting expansion foam into the cavity, between the shoulder and the opening.

[0035] - the method further comprises, after the step S5 of inserting the locking member, a step S6 of positioning the end of the fiber-reinforced root portion of the blade below the locking member or against the lower face of the base, and attaching a cover to said end in order to keep the locking member bearing against the two fiber-reinforced root portions of the blade.

[0036] According to a third aspect, the present invention provides a gas turbine engine comprising a fan, the fan comprising a hub and blades extending radially from the hub, the blades being blades according to the first aspect, each blade being rotatably mounted relative to the hub around a corresponding pivot axis, the engine further comprising an actuating mechanism adapted to be controlled to rotate the blades around their pivot axis to adjust the pitch angle of the blades.

[0037] According to a fourth aspect, the present invention provides an aircraft comprising a gas turbine according to the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Other characteristics, objects and advantages of the present invention will become apparent from the following description, which is purely illustrative and non-limiting and must be read with reference to the accompanying drawings, in which:

[0039] Figure 1 An example of an engine including an unducted fan is schematically shown;

[0040] Figure 2 schematically illustrates fan blades and an actuation mechanism that enables adjustment of the pitch angle of the fan blades;

[0041] Figure 3A Schematically shows a fan blade according to a first embodiment of the present invention;

[0042] Figure 3B Schematically shows a fan blade according to a second embodiment of the present invention;

[0043] Figure 3C Schematically shows a fan blade according to a third embodiment of the present invention;

[0044] Figure 4 A composite material structure forming part of a blade is schematically shown;

[0045] Figures 5 to 8 Schematically illustrating the steps of a method of manufacturing an exemplary embodiment of a fiber reinforcement for a blade according to an embodiment of the present invention;

[0046] Figure 9 is a flow chart of the steps of a method according to an embodiment of the present invention.

[0047] Similar items have the same reference numerals throughout the drawings. DETAILED DESCRIPTION

[0048] exist Figure 1 In the figure, the engine 1 is an open rotor type engine, in what is currently called a "propeller" configuration (i.e., an unducted fan is placed behind the electric generator, with air intakes on the sides and Figure 1 on the right side of the ).

[0049] The engine comprises a nacelle 2 for attachment to an aircraft fuselage and an unducted fan 3. Fan 3 comprises two counter-rotating fan rotors 4 and 5. In other words, when the engine 1 is running, rotors 4 and 5 are driven in opposite directions relative to the nacelle 2 about one and the same axis of rotation X (which coincides with the main axis of the engine).

[0050] exist Figure 1 In the example shown, engine 1 is an open rotor engine in a "pusher" configuration with counter-rotating fan rotors. However, the present invention is not limited to this configuration. The present invention is also applicable to open rotor engines in a "puller" configuration (i.e., the fan is placed upstream of the electric generator, with the air inlet located in front of, between, or near the rear of the two fan rotors).

[0051] Furthermore, the present invention is also applicable to engines having different architectures, such as an architecture including a fan rotor including movable blades and a fan stator including fixed blades, or an architecture including a single fan rotor.

[0052] The invention is applicable to architectures of the turboprop type (comprising a single fan rotor).

[0053] exist Figure 1 In FIG, each fan rotor 4, 5 comprises a hub 6 rotatably mounted relative to the nacelle 2 and a plurality of blades 7 attached to the hub 6. The blades 7 extend substantially radially relative to the axis of rotation of the hub.

[0054] like Figure 2 As shown, fan 3 also includes an actuating mechanism 8 that allows the pitch angle of the rotor blades to be collectively adjusted in order to adapt the engine's performance to the different phases of flight. To this end, each blade 7 includes a fastening element 9 arranged at the blade root. Fastening element 9 is rotatably mounted relative to hub 6 about a pivot axis Y. More precisely, fastening element 9 is rotatably mounted inside a housing 10 formed in hub 6 via balls 11 or other rolling elements.

[0055] The actuating mechanism 8 comprises an actuator 13 comprising a body 12 attached to the hub 6 and a rod 14 suitable for being driven in translation relative to the body 12. The actuating mechanism 8 also comprises an annular slider 15 fixedly mounted on the rod 14 and a pin 16 fixedly mounted on the fastening part 9. The pin 16 is suitable for sliding in the slider 15 and rotating relative to the slider 15, in such a way as to convert the translational movement of the rod 14 into a rotational movement of the fastening part 9 and therefore into a rotational movement of the blade 7 relative to the hub 6 about its pivot axis Y.

[0056] Fan blade 7( Figure 2 ) including composite material structure 17( Figure 4 ), the fastening parts at the root of the blade 7, the retaining base 18 and the locking part 19.

[0057] The composite material structure 17 includes a fiber reinforcement 33 obtained by three-dimensional weaving and a matrix 34 in which the fiber reinforcement 33 is embedded.

[0058] The fiber reinforcement can be formed on the basis of a fiber preform, which is made of a single part obtained by three-dimensional weaving or multi-layer weaving with variable thickness. In particular, the fiber reinforcement can include fibers made of carbon, glass, aramid and / or ceramic. At the same time, the matrix is ​​usually a polymer matrix, such as epoxy resin, bismaleimide or polyimide, or a carbon matrix. The blade 7 is then molded by a vacuum resin infusion process of the Resin Transfer Molding (RTM) or Vacuum Resin Transfer Molding (VARTM) type.

[0059] The fiber reinforcement is woven in such a way that the fiber reinforcement 33 comprises warp threads which extend continuously inside the blade part with the aerodynamic profile 21 and inside the blade root part 22 .

[0060] The matrix 34 is made of plastic, for example an epoxy-type resin, which covers the threads of the fiber reinforcement 33 .

[0061] The composite structure 17 comprises an aerodynamically contoured blade part 21 and a blade root part 22. The aerodynamically contoured blade part 21 is adapted to be positioned in the air flow to generate lift when the engine is running. The blade root part 22 is intended to enable the composite structure 17 to be attached to the fastening part 9.

[0062] The blade root part 22 comprises two portions 23 which are continuously connected to the blade part 21 at the level of a coupling region 24. In an embodiment, each portion 23 has a thickness which increases along the portion 23 in a direction away from the aerodynamically profiled blade part 21 .

[0063] The fastening member 9 is formed of metal, for example martensitic steel. The fastening member 9 comprises a wall having an outer surface having a shape of revolution. The outer surface has two circular grooves 27 which are suitable for forming rolling tracks for balls or other rolling elements.

[0064] The wall of the fastening part 9 defines a cavity configured to accommodate the blade root part 22 of the composite structure 17. The wall shows a first opening 29 of generally rectangular shape, through which the composite structure 17 extends, so that the blade part 21 is located outside the fastening part 9. The fastening part 9 also has a second opening 30, which is wider than the first opening 29 and is located below the blade root part 22, on the opposite side of the fastening part 9 relative to the first opening. Where applicable, this second opening 30 may be circular.

[0065] The fastening member 9 further comprises a shoulder 10 extending from the wall into the cavity. The shoulder 10 extends continuously or discontinuously along the inner circumference of the wall.

[0066] A holding base 18 and a locking member 19 are also arranged inside the cavity.

[0067] The base 18 comprises a support configured to abut against the shoulder 10 of the fastening member 9 and a channel 39 formed in the support, the support being adapted to receive the portion 23 of the blade root member 22 of composite material structure. In an embodiment, the base 18 is a bushing whose outer periphery corresponds to the inner periphery of the fastening member 9, such that when the bushing bears on the shoulder 10, the outer periphery of the bushing is in contact with the inner periphery of the blade root fastening member 9.

[0068] The base 18 is made of metal, for example, martensitic steel, aluminum or titanium.

[0069] The locking member 19 is placed between the two parts 23 of the blade root part 22 in order to keep the two parts 23 of the blade root part 22 separated from each other. The locking member 19 abuts against the coupling area 24 of the blade root part 22 so that each part 23 of the blade root part 22 is then pressed against the support by the locking member 19.

[0070] Thus, when the blade root part 22 is placed in the blade fastening part 9, the portion 23 is fastened between the side faces of the support and the locking part 19. Consequently, the two portions 23 of the blade root part 22 are separated from each other by the locking part 19 and pressed against the side faces to prevent the exit of the blade root part 22 of the cavity through the opening 29.

[0071] To enhance the fastening, the side surfaces of the support defining the channel 39 may be inclined, i.e. the channel 39 diverges from the upper face 38 a of the support (corresponding to the face 38 a of the support adapted to bear against the shoulder 10) in the direction of the lower face 38 b (opposite the upper face 38 a). The side surfaces may be substantially flat.

[0072] Advantageously, locking the portion 23 of the blade root part 22 using the base 18 and the locking part 19 makes it possible to benefit from the advantages of a dagger-type fastening (radial mounting in the hub) while maintaining the absorption of centrifugal forces via the specific support surfaces of the pinned fastener (the sides of the support).

[0073] Where applicable, the connection between the lower face 38b and the side faces may be chamfered or blunted to avoid any damage to the composite structure 17 .

[0074] The locking member may have any shape suitable for enabling the portion 23 to be fastened to the side of the support. Figure 3A and Figure 3C As shown, the locking element may have a prism shape with an apex angle such that when the locking element 19 is placed in the fastening element 9, the faces of the prism are substantially parallel to the side faces. Figure 3B As shown, the locking member may have a generally cylindrical shape of revolution.

[0075] Fan blade 7 further comprises a cover 31 adapted to be attached to fastening element 9 in order to exert a force on locking element 19 that tends to press locking element 19 against blade root portion 23 and, in turn, press the locking element and blade root portion against the support. When cover 31 is attached to fastening element 9, it closes second opening 30. Thus, when the second opening is circular, the cover can be attached to fastening element 9, in particular, by means of a screw connection.

[0076] At least one through hole 32 is also formed in the cover to enable injection of the matrix to cover the fiber reinforcement of the composite material structure 17 .

[0077] Preferably, the cover 31 is made of metal, such as martensitic steel, aluminum or titanium.

[0078] In the first embodiment, the end 23 a of each portion 23 of the blade root part 22 is folded under the locking member 19. The locking member 19 is therefore housed in the portion 23 and is not in direct contact with the cover 31. Consequently, the attachment of the cover 31 to the fastening member 9 has the effect of pressing the end 23 a of the portion 23 against the locking member 19.

[0079] In the second embodiment, the end 23a of each portion 23 of the blade root element 22 is folded outwards so as to extend below the lower face 38b of the support in the direction of the wall of the fastening element 9. The locking element 19 then comes into contact with the cover 31, while the portion 23 is clamped between the cover 31 and the support of the base 18.

[0080] Whatever the embodiment, the portion 23 of the blade root part 22 is locked in position by the cover 31. Consequently, the portion 23 cannot move in the fastening part 9, on the one hand because the portion 23 is locked by the cover 31 and on the other hand because the portion 23 is pressed against the support of the base 18 by the locking part 19.

[0081] Furthermore, an expanding foam 40 is injected into the cavity of the fastening part 9, between the first opening 29 and the base 18, in order to ensure the positioning of the composite structure 17 during the injection process and to absorb the transverse forces exerted on the blade 7. Thus, the foam 40 makes it possible to fill the upper part of the cavity and stiffen the blade root part 22, which extends from the coupling region 24 in the direction of the aerodynamically profiled blade part 21, without significantly affecting the mass of the blade 7. In particular, the injection of the expanding foam 40 helps prevent any movement of the blade root part 22 in the fastening part 9, thereby suppressing friction and, therefore, premature damage caused by vibration fatigue, which is often observed in open rotors on pinned fasteners.

[0082] In particular, the foam 40 may belong to at least one of the following families: polyurethane foam, phenolic foam, polystyrene foam.

[0083] The blade 7 also comprises a seal 20 placed in the first opening 29, between the composite structure 17 and the edge of the first opening 29 surrounding the composite structure 17. The seal 20 makes it possible to fill the remaining gap between the composite structure 17 and the fastening part 9.

[0084] In particular, the seal may include an elastomer, such as a Room Temperature Vulcanizing (RTV) silicone elastomer.

[0085] Figures 5 to 9 The steps of a method S for producing a fan blade 7 according to a possible embodiment of the invention are shown.

[0086] According to the first step S1 ( Figure 5 ), a fiber reinforcement 33 is produced by three-dimensional weaving on a jacquard-type loom. During the weaving process, warp bundles C (or warp strands) are arranged in multiple layers, each consisting of several hundred threads. Weft threads (T) (or weft strands) are interwoven with the warp threads C in this way to connect the different layers of warp threads C to each other.

[0087] In the example shown, the three-dimensional weave is an “interlock” weave. The term “interlock” refers to a weave in which each layer of weft threads connects several layers of warp threads, with all threads of the same weft column having the same motion in the weaving plane.

[0088] Other known types of three-dimensional weaving may be used, in particular those described in document WO 2006 / 136755.

[0089] like Figure 6 As shown, the steps of weaving the unprocessed (or preformed) fiber reinforcement 33 include, in sequence: weaving a temporary fiber reinforcement portion 26 (which will be discarded later in the manufacturing process), weaving two blade root fiber reinforcement portions 35 for forming portion 23, and then weaving a blade fiber reinforcement portion 36 for forming the remaining portion of the blade root 22.

[0090] The temporary fiber reinforcement portion 26 is woven by interlacing all the warp threads C required to produce the fiber reinforcement 33. Once the weft thread column reaches a predetermined width l, a break D begins between two consecutive warp layers C. Next, two blade root fiber reinforcement portions 35 are woven parallel to each other, while being separated by a loosened area D. Next, the break D stops at the level of the coupling area 24, and the blade fiber reinforcement portion 36 is woven.

[0091] Thus, each of the two blade root reinforcement portions 35 comprises a warp thread C which extends inside the blade fiber reinforcement portion 36 .

[0092] Figure 7AThis is a schematic, enlarged cross-sectional view of multiple layers of warp threads C1 to C6 in a portion of the fiber reinforcement that does not include any breaks. In this example, the fiber reinforcement includes six layers of warp threads C1 to C6 extending transversely to the cross section. The multiple layers of warp threads C1 to C6 are interconnected by five layers of weft threads T1 to T5 extending into the cross section (or weaving plane).

[0093] Figure 7B : is an enlarged cross-sectional view of the multi-layer warp threads C1 to C6 in the portion of the fiber reinforcement including the disconnected portion. The three layers of warp threads C1 to C3 are interconnected by two layers of weft threads T1 and T2, while the three layers of warp threads C4 to C6 are interconnected by two layers of weft threads T4 and T5. Figure 7B As can be seen in FIG, the warp threads C3 and C4 of the two adjacent layers are not connected to each other by the weft threads, thereby forming a break in the fiber reinforcement.

[0094] In an embodiment, Figure 6 As can be seen in the figure, each blade root fiber reinforcement part 35 can be woven with continuous weft yarns T with different fineness, and the fineness decreases along the weaving direction (weaving direction indicated by the arrow), that is, the closer to the blade fiber reinforcement part 36, the fineness decreases.

[0095] It should be remembered that "denier" refers to a quantity that characterizes the fineness of a thread: it is defined as the mass of the thread per unit length. The standard unit of measurement for denier is Tex (mass in grams of 1000 meters of thread) or Decitex (mass in grams of 10,000 meters of thread). Other units, such as denier, metric or imperial numerical values ​​may also be used.

[0096] Thus, each blade root fiber reinforcement portion 35 has a thickness e that decreases closer to the blade fiber reinforcement portion 36. Each blade root fiber reinforcement portion has a thickness e1 at the blade root and a thickness e2 at the connection with the blade fiber reinforcement portion 36 that is smaller than e1.

[0097] However, this embodiment is not restrictive, as the blade root fiber reinforcement portion 35 may be of constant thickness.

[0098] When weaving a fiber reinforcement 33 of variable thickness and width, a certain number of warp threads C are not woven, which makes it possible to define a desired continuously variable profile, width and thickness of the fiber reinforcement 33 .

[0099] The warp threads C and weft threads T located at the limits of the fabric mass (or "float") are also cut, in this way extracting the fiber reinforcement 33 ( Figure 8 ).

[0100] Next, the preform is contoured to obtain the finished fiber reinforcement. Contouring means cutting the preform flat along the top leading and trailing edges (leaving excess length at these three cuts). Contouring is also done along the lower air path and on the sides of the blade root component.

[0101] Furthermore, the temporary fiber reinforcement portion 26 is severed for removal such that the break D forms an opening 37 which opens between the two blade root reinforcement portions 35. The contouring and severing of the blade root portion may be done by a pressurized water jet.

[0102] According to a second step S2 , the fastening part 9 is produced, for example by machining, to form a cavity, a first opening 29 , a second opening 30 , a shoulder 10 and, if applicable, a thread at the level of the second opening 30 , to enable the cover 31 to be screwed on.

[0103] According to a third step S3 , the base 18 is inserted into the fastening part 9 via the second opening 30 and placed against the shoulder 10 .

[0104] According to a fourth step S4, the blade root fiber reinforcement portion 35 is inserted into the cavity of the fastening component 9 through the passage 39 of the base 18 via the first opening 29 of the fastening component 9. Once the blade root fiber reinforcement portion 35 has been inserted into the cavity, the root fiber reinforcement portion 35 extends inside the cavity of the fastening component 9 while passing through the passage 39 of the base 18, while the blade fiber reinforcement portion 36 extends outside the fastening component 9.

[0105] According to a fifth step S5 , the locking member 19 is inserted through the second opening 30 between the two blade root fiber reinforcement parts 35 in order to separate the two parts 35 from each other.

[0106] According to a sixth step S6, the ends of the blade root reinforcement parts 35 are placed against the lower face 38b of the support, or below the locking element 19, and then the cover part 31 is attached to the fastening element 9 in order to lock the two blade root reinforcement parts 35 and to keep the locking element 19 supported on said parts. In particular, the cover 31 is attached in such a way that it exerts a compressive force on the blade root reinforcement parts 35, which tends to drive the locking element 19 between the two parts towards the aerodynamically contoured blade part 21 and press the locking element and the two parts against the side of the support. This installation ensures that the two blade root reinforcement parts 35 remain separated from each other, so as to resist the centrifugal forces exerted on the blade 7 during engine operation by geometric effects.

[0107] According to a seventh step S7 , the expanding foam 40 is injected so as to fill the cavity of the upper face 38 a of the support up to the first opening 29 and then densified by polymerization.

[0108] Note that, in a variant embodiment, this step of injecting and densifying the expansion foam 40 can also be completed before the step of inserting the base 18. In this case, during the second step S2, the fastening part 9 is pre-machined to produce a depression whose contour generally corresponds to the portion of the cavity extending between the shoulder 10 and the first opening 29. The expansion foam 40 is then injected into this depression and densified, and the fastening part 9 and the expansion foam 40 are then machined to produce the remaining portion of the cavity, the first opening 29, the second opening 30, the shoulder 10, and, if applicable, the threads at the level of the second opening 30, so that the cover 31 can be screwed on. The rest of steps S3 to S6 then remain unchanged.

[0109] According to an eighth step S8 , the seal 20 is inserted into the first opening 29 .

[0110] According to the ninth step S9 ( Figure 9 ), the obtained assembly (comprising the fibre reinforcement 33, the fastening part 9, the expanding foam 40, the base 18, the locking part 19, the seal 20 and the cover 31) is placed in a mould (not shown) having a cavity in the shape of the final part to be moulded, i.e. the fan blade 7.

[0111] According to a tenth step S10, plastic (referred to as "matrix") is injected into the mold through one or more holes 32 formed in the cover 31, in such a way as to impregnate the entire fiber reinforcement 33. The injection of the plastic can be achieved by an injection technique such as resin transfer molding (RTM) or vacuum resin transfer molding (VARTM). The injected plastic is, for example, a thermosetting liquid composition containing an organic precursor of the matrix material. The organic precursor is often a polymer, such as a resin, diluted in a solvent, where applicable.

[0112] In a well-known manner, the plastic is heated in such a way that it polymerizes, for example by cross-linking. To this end, the mold is placed in a furnace. The resulting component is then demoulded and contoured by machining the leading edge, trailing edge, and blade tip to obtain the desired shape. The lower portion of the blade is also machined.

[0113] The composite material structure 17 of the blade 7 is formed with a plastic-impregnated reinforcement 33 forming a matrix 34 .

Claims

1. A blade (7), comprising: - a composite material structure (17) comprising a fiber reinforcement (33) obtained by three-dimensional weaving and a matrix (34) embedded in said fiber reinforcement (33), said composite material structure (17) comprising a blade part (21) having an aerodynamic profile and a blade root part (22), said blade root part (22) comprising two parts (23), each of said parts being connected to said blade part (21); a blade root fastening member (9), the blade root fastening member comprising a wall defining a cavity and a first opening (29) formed in the wall, the composite material structure (17) extending through the first opening (29) such that the blade component (21) is located outside the blade root fastening member (9) and the blade root component (22) is located within the cavity, the blade root fastening member (9) further comprising a shoulder (10) extending from the wall into the cavity; - a base (18) arranged in the cavity, the base (18) comprising: a support configured to abut against the shoulder (10) of the blade root fastening part (9); and a passage (39) formed in the support, the portion (23) of the blade root component (22) of the composite material structure extending through the passage (39); and - a locking member (19) arranged in the cavity between the two portions (23) of the blade root member (22) such that each portion (23) of the blade root member is pressed against the support by the locking member (19).

2. The blade (7) according to claim 1, further comprising an expansion foam (40) arranged in the cavity between the base (18) and the first opening (29).

3. The blade (7) according to claim 1 or 2, wherein: The end portion (23a) of each portion (23) of the blade root member (22) is folded under the locking member (19) or placed against the lower surface of the base (18).

4. The blade (7) according to claim 3, further comprising a cover (31), which is in contact with the end (23a) of the portion (23) of the blade root member (22) and is configured to be attached to the blade root fastening member (9) so as to lock the portion (23) and the locking member (19).

5. The blade (7) according to claim 1 or 2, wherein: The fiber reinforcement (33) comprises a blade fiber reinforcement portion (36) and two blade root fiber reinforcement portions (35), wherein the blade root fiber reinforcement portions (35) are each woven continuously with the blade fiber reinforcement portion (36), and the two blade root fiber reinforcement portions (35) are separated by a loose area (D) obtained during the three-dimensional weaving of the fiber reinforcement (33).

6. The blade (7) according to claim 1 or 2, wherein: The side of the support defining the channel (39) is inclined so that the channel (39) is divided in the direction of a second opening (30) of the blade root fastening part (9), the second opening (30) being located below the blade root part (22) on the side opposite to the blade root fastening part (9) with respect to the first opening (29).

7. A method for manufacturing a blade (7) according to any one of claims 1 to 6, said method comprising manufacturing said blade based on a fiber reinforcement (33) obtained by three-dimensional weaving (S1), said fiber reinforcement (33) comprising a blade fiber reinforcement part (36) and two blade root fiber reinforcement parts (35), said method comprising the following steps: S2: Producing the blade root fastening component (9) to form the cavity and the shoulder (10); S3: placing the base (18) in the blade root fastening component (9) against the shoulder (10); S4: placing the fiber reinforcement (33) through the first opening (29) in the blade root fastening component (9), such that the blade fiber reinforcement portion (36) is located outside the blade root fastening component (9) and the two blade root fiber reinforcement portions (35) are located inside the cavity; S5: inserting the locking component (19) into the cavity and locating it between the two blade root fiber reinforcement parts (35), so that each part (23) of the blade root part is pressed against the support by the locking component (19); S9: placing the fiber reinforcement (33), the blade root fastening component (9), the base (18) and the locking component (19) in a mold; S10: Injecting plastic into the mold to form the composite material structure (17), the composite material structure comprising the fiber reinforcement (33) and a matrix (34) embedded in the fiber reinforcement (33).

8. The method according to claim 7, further comprising: Prior to the step S10 of injecting plastic, step S7 of injecting expansion foam (40) into the cavity at a position between the shoulder and the first opening (29).

9. The method according to claim 7 or 8, further comprising: After step S5 of inserting the locking member (19), step S6 is performed, wherein the end portion (23a) of the blade root fiber reinforcement portion (35) is positioned below the locking member (19) or against the lower surface (38b) of the base (18), and a cover (31) is attached to the end portion (23a) to keep the locking member (19) supported against the two blade root fiber reinforcement portions (35).

10. A gas turbine engine (1), comprising a fan, the fan comprising a hub (6) and blades (7), the blades extending radially from the hub (6), the blades (7) being blades (7) according to any one of claims 1 to 6, each of the blades (7) being rotatably mounted relative to the hub (6) about a corresponding pivot axis (Y), the gas turbine engine (1) further comprising an actuating mechanism (8) adapted to be controlled to rotate the blades (7) about the pivot axis (Y) of the blades so as to adjust the pitch angle of the blades (7).

11. Aircraft comprising a gas turbine engine (1) according to claim 10.

Images