Hollow propeller blade or hollow vane made of organic matrix composite material

Abstract

The present invention relates to a hollow propeller blade (1) or hollow vane (1) made of organic matrix composite material, comprising (i) a first portion (3) defining an aerodynamic profile and comprising a first fibre reinforcement obtained by three-dimensional weaving, and (ii) a hollow second portion (5), located inside the first portion and rigidly attached to the first portion, wherein the second portion comprises a second fibre reinforcement comprising a fibre stack of at least (a) a first layer of unidirectional fibres oriented between -65° and -25° with respect to a radial direction (DR) of the vane or propeller blade; and (b) a second layer of unidirectional fibres oriented between +25° and +65° with respect to the radial direction. The present invention also relates to associated manufacturing methods.

Description

Description Title of the invention: Hollow blade or hollow propeller blade made of organic matrix composite material Technical Field

[0001] This disclosure relates to a hollow blade or propeller blade made of an organic matrix composite material having improved torsional performance, as well as associated manufacturing methods. Prior art

[0002] The use of a composite material makes it possible to produce lighter turbomachine propeller blades or blades compared to the use of a metallic material. Their use contributes to optimizing the performance of turbomachines, in particular by reducing the overall mass of the turbomachine, thus reducing fuel consumption which in turn leads to a reduction in harmful emissions (CO, CO2, NOx, etc.).

[0003] It may be desirable to increase the size of propeller blades or vanes in order to improve engine performance, which makes controlling the mass of the components involved all the more important. One solution to this is to offer hollow parts made of composite material.

[0004] The manufacture of hollow composite parts has been proposed in the state of the art. Thus, document FR 3 124 198 proposes forming a hollow outlet guide vane by shaping a fiber blank by introducing a shaping insert made of fugitive material and removing this insert after forming the matrix.

[0005] Such a technique gives satisfactory results but imposes constraints on the manufacturing process, in particular maintaining a sufficient size output in the final part after formation of the matrix to evacuate the fugitive material, and ensuring that this material is compatible with the pressure and temperature conditions implemented during the formation of the matrix so as not to affect the shape of the part to be obtained. These conditions can be limiting if it is desired to form parts of larger size and / or of complex geometry so that other solutions can be sought. ER 1 669 547 is also known which discloses a composite blade.

[0006] Furthermore, it remains possible to improve the torsional performance of composite propeller blades or vanes reinforced with a three-dimensional fabric.

[0007] The present invention aims to address all or part of the aforementioned drawbacks. Statement of the invention

[0008] The present disclosure relates to a hollow blade or hollow propeller blade made of organic matrix composite material, comprising (i) a first composite part having an external surface defining an aerodynamic profile and comprising a first fiber reinforcement obtained by three-dimensional weaving, and (ii) a second hollow composite part, located inside the first part and secured to an internal surface of the first part, the second part comprising a second fiber reinforcement comprising a fiber stack of at least (a) a first layer of unidirectional fibers oriented with a first angle of between -65° and -25° relative to a radial direction of the blade or propeller blade, and (b) a second layer of unidirectional fibers oriented with a second angle of between +25° and +65° relative to the radial direction.

[0009] The present invention provides a hollow blade or a hollow propeller blade having a hybrid fiber reinforcement comprising, on the one hand, a three-dimensional fabric in the first part defining the aerodynamic profile and, on the other hand, a fiber stack with a particular fiber orientation so as to improve the performance of the part in torsion compared to the case where the reinforcement is only formed by the three-dimensional fabric.

[0010] In an exemplary embodiment, the first angle is between -55° and -35° relative to the radial direction, and the second angle is between +35° and +55° relative to the radial direction. In particular, the first angle may be between -50° and -40° relative to the radial direction, and the second angle may be between +40° and +50° relative to the radial direction.

[0011] Such a feature allows to further improve the torsional performance of the part.

[0012] In an exemplary embodiment, the first angle is between -65° and -55° relative to the radial direction, and the second angle is between +55° and +65° relative to the radial direction.

[0013] In an exemplary embodiment, the fibrous stack further comprises (c) a third layer of unidirectional fibers oriented at a third angle of between -15° and +15° relative to the radial direction.

[0014] Such a characteristic makes it possible to further functionalize the second reinforcement by enriching the fiber orientations so as to further improve the mechanical performance of the part, in particular its tensile properties (centrifugal force).

[0015] In particular, the third angle can be between -5° and +5° relative to the radial direction.

[0016] Such a characteristic makes it possible to further improve the mechanical performance of the part, in particular its tensile properties (centrifugal force).

[0017] In an exemplary embodiment, the fibrous stack further comprises (d) a fourth layer of unidirectional fibers oriented with a fourth angle of between +75° and +105° relative to the radial direction. In particular, the fourth angle may be between +85° and +95° relative to the radial direction.

[0018] More specifically, the fibrous stack can be quasi-isotropic.

[0019] Such a feature makes it possible to further improve the performance of the part, in particular its compression and traction properties as well as its properties in the thickness direction (between the intrados and the extrados).

[0020] In an exemplary embodiment, the fibrous stack is formed by repeating a plurality of units each comprising a superposition of the first and second layers, in particular added to the third layer and, more particularly still, to the fourth layer.

[0021] Repeating the multi-layer pattern further improves the mechanical performance of the part.

[0022] In one embodiment, the fiber stack is braided.

[0023] The use of a fibrous stack obtained by a braiding technique advantageously makes it possible to further improve the mechanical strength of the part by avoiding the presence of a rupture initiation zone in the second reinforcement.

[0024] In an exemplary embodiment, the second part has an internal surface delimiting an internal volume of the blade or propeller blade which has a roughness Ra less than or equal to 3.2 pm, for example between 0.6 pm and 3.2 pm.

[0025] Roughness Ra can be measured with a 3D profilometer.

[0026] This characteristic of the surface state can also be found on the precursor of the second part which will be introduced later, and makes it easier to extract the shape (mandrel or core) used during the preliminary stage of manufacturing the precursor, before assembly with the first reinforcement.

[0027] The present disclosure also relates to an unducted fan for mounting on an aircraft, comprising a hub comprising attachment portions, and a plurality of propeller blades as described above mounted on the attachment portions.

[0028] The present disclosure also relates to a ducted fan for mounting on an aircraft, comprising a hub comprising attachment portions, and a plurality of blades as described above mounted on the attachment portions.

[0029] The present disclosure also relates to a method of manufacturing a hollow vane or hollow propeller blade as described above, comprising: - obtaining an assembly comprising (i) the first fibrous reinforcement defining an internal cavity, and (ii) a precursor of the second hollow-shaped part consolidated and comprising the second reinforcement densified by a partially cured thermosetting polymer, the precursor being located inside the internal cavity and giving its shape to the first reinforcement, - the introduction of a thermosetting resin into a porosity of the first reinforcement after obtaining the assembly, and - co-cooking of the thermosetting resin thus introduced with the polymer.

[0030] In the process aspect introduced above, the precursor is present in the assembly in the consolidated state, that is to say that it can be handled while retaining its shape without the assistance of holding tools and that it is sufficiently rigid to shape the first reinforcement and that its shape is not affected when the resin is introduced into the porosity of the first reinforcement.

[0031] The consolidated state is obtained by partial curing of the polymer, that is to say that the polymer is incompletely polymerized. It may have a degree of progress of polymerization greater than or equal to 80%, for example between 80% and 90%. For a given polymer, the degree of progress of polymerization can be determined by differential scanning calorimetry (DSC). The degree of progress of polymerization of the polymer is sufficient for the precursor to have the desired degree of rigidity. However, the polymerization is not complete to allow co-curing and thus obtain a bonding of the second part to the internal surface of the first part. This co-curing makes it possible to polymerize the thermosetting resin, introduced into the first reinforcement, with the incompletely polymerized polymer.This allows covalent bonds to be created between the polymer chains present, resulting in the joining of the first and second parts.

[0032] The process described uses a precursor for the second part to shape the first reinforcement to the desired shape. The precursor has the advantage of not having to be removed from the densified part, which eliminates the constraints related to the elimination of the temporary inserts explained above. In addition, the use of the rigid precursor avoids any risk of affecting the shape of the part when introducing the resin.

[0033] In an exemplary embodiment, the resin is introduced into the porosity of the first reinforcement by resin transfer molding. This technique corresponds to the technique known by the acronym RTM (called “Resin Transfer Molding” in English). The person skilled in the art will recognize that other techniques can be implemented to introduce the resin as will be described below. Brief description of the drawings [Fig. 1] Figure 1 schematically represents an example of a hollow vane or hollow propeller blade according to the invention. [Fig. 2] Figure 2 schematically represents a sectional view along II-II of the part of figure 1. [Fig. 3] Figure 3 represents, schematically and partially, an example of a fibrous stack that can be implemented within the framework of the invention. [Fig. 4] Figure 4 represents, schematically and partially, another example of a fibrous stack that can be implemented within the framework of the invention. [Fig. 5] Figure 5 represents, schematically and partially, another example of a fibrous stack that can be implemented within the framework of the invention. [Fig. 6] Figure 6 shows, schematically and partially, an example of an unducted fan according to the invention. [Fig. 7] Figure 7 shows, schematically and partially, an example of a ducted fan according to the invention. [Fig. 8] Figure 8 represents a succession of steps of an example of a method for manufacturing a hollow blade or a hollow propeller blade according to the invention. [Fig. 9] Figure 9 represents, schematically and partially, the production by braiding technique of a fibrous stack which can be implemented within the framework of the invention. Description of the embodiments

[0034] The invention is now described by means of figures, present for descriptive purposes to illustrate certain embodiments of the invention and which should not be interpreted as limiting the latter.

[0035] For the sake of brevity, the word "part" is used in the following to refer indifferently to the hollow vane or the hollow propeller blade.

[0036] The part 1 illustrated in Figure 1 is made of organic matrix composite material. It is formed of two parts 3, 5 each made of organic matrix composite material which are secured to each other. The details for achieving this bonding will be discussed later in connection with Figure 8, which concerns the manufacture of the part.

[0037] The first part 3 defines the external part of the part 1. The first part 3 comprises a first fibrous reinforcement which has been obtained by three-dimensional weaving and which is densified by a first organic matrix. The first part 3 has a surface SE3 which defines an aerodynamic profile and in particular a leading edge 32 and a trailing edge 34. The first part 3 extends along a radial direction DR of the part 1 between an internal radial end 31, and an external radial end 33.

[0038] The second part 5 is distinct from the first part 3 and has a hollow shape which defines an internal volume V of the part 1 (see figure 2). The second part 5 is located inside the first part 3. The second part 5 comprises a second fibrous reinforcement which comprises a fibrous stack having a controlled fibrous orientation and which is densified by a second organic matrix. The second fibrous reinforcement may be made of a material identical to or different from that forming the first fibrous reinforcement. The first and second reinforcements may be made of carbon fibers, glass fibers, or a mixture of such fibers. The second organic matrix may be identical to or different from the first organic matrix. The second part 5 has an internal surface SI5 which defines the volume V and a surface SE sexternal which is in contact with an internal surface SI3 of the first part 3. The joining between the first 3 and the second 5 parts takes place on the interface between the surfaces SE s and SI3, and can be ensured by covalent bonds between the first and second matrices.

[0039] The SI5 surface advantageously has a relatively smooth structure, with a roughness Ra less than or equal to 3.2 pm, for example between 0.6 pm and 3.2 pm.

[0040] The following describes, in connection with figures 3 to 5, different examples of fibrous stacks which can be implemented within the framework of the invention.

[0041] Generally speaking, the second reinforcement may consist essentially of the fiber stack. Generally speaking, the fiber stack is formed by a superposition of at least two layers of unidirectional fibers having different orientations. The fibers belonging to a layer of unidirectional fibers extend substantially in the same direction. The layers of the stack follow one another along a stacking direction which is transverse, for example normal, to the DR direction.

[0042] The example of figure 3 shows a first possible stack 51 which comprises a layer 151 of unidirectional fibers oriented with an angle Oi here equal to -45° relative to the direction DR, and a layer 251 of unidirectional fibers, superimposed on the layer 151, oriented with an angle a2here equal to +45° relative to the DR direction. Layer 251 is in contact with layer 151.

[0043] The example of Figure 4 shows a second possible stack 52 which comprises unidirectional layers 151, 251 similar to those of Figure 3 supplemented by a layer 351 of unidirectional fibers and a layer 451 of unidirectional fibers. Layers 351 and 451 are superimposed on layers 151, 251. Layer 351 is oriented with an angle a3ici equal to +90° relative to the DR direction, and layer 451 is oriented with an angle a4ici equal to 0° relative to the DR direction. Layer 351 is in contact with layer 251 and layer 451 is in contact with layer 351. Layer 351 is located between the second layer 251 and layer 451, and layer 251 is located between layer 151 and layer 351. The example in Figure 4 corresponds to a so-called quasi-isotropic fiber stack. When moving along the stacking direction, we pass in this order through layer 151, layer 251, layer 351 and layer 451.

[0044] The example of Figure 5 shows a third possible stack 53 which comprises a repetition of several units Ul and U2. The unit Ul is similar to the superposition illustrated in Figure 4 and the unit U2 is symmetrical to the unit Ul. The stack can continue along the stacking direction with an alternation between the units Ul and U2, i.e. with a second unit Ul following the unit U2 then a second unit U2 following the second unit Ul, etc. According to a variant not illustrated, a repetition of the two-layer unit 151, 251 illustrated in Figure 3 could be achieved by alternating the layers 151 and 251 along the stacking direction. According to another variant not illustrated, the 90° layer 351 can be omitted. The stack can thus be formed from layers 151, 251 and 451, possibly repeated as described above.Generally, the stack may comprise at least 10 layers of unidirectional fibers as described above, for example between 10 and 30 such layers.

[0045] The part 1 may be intended to be mounted on an aircraft engine. Thus, Figure 6 represents an engine 100 of the unducted type (called "open rotor"). The engine 100 comprises a nacelle intended to be fixed to a fuselage of an aircraft, and an unducted fan 111. The fan rotor 111 comprises a hub rotatably mounted relative to the nacelle and hollow propeller blades 11 as described above which are fixed to the hub. They may be mounted inside a variable pitch mechanism arranged in the hub. The invention is also applicable to turboprop type architectures. The variant illustrated in Figure 7 relates to a ducted fan 211 of an aircraft engine which comprises a plurality of blades 21 as described above which are located opposite a fan casing 213.

[0046] An application of the part as a moving part, mounted on a shrouded or unshrouded fan rotor, has been described. However, it does not go beyond the scope of the invention if the part is a static turbomachine part such as an outlet guide vane (OGV). The manufacturing process of the part will now be discussed in connection with Figures 8 and 9.

[0047] The fiber stack is produced with the desired fiber orientation during step E10 by implementing techniques known per se. Thus, Figure 9 illustrates the production of a stack 51 of the type illustrated in Figure 3 by a braiding technique. The illustrated braiding machine M comprises a plate M1 and a plurality of yarn feed spindles M3 which circulate on a guide path M5. The stack 51 is braided on a form M7 such as a mandrel. The person skilled in the art will recognize that other techniques can be implemented to produce the stack such as filament winding.

[0048] Generally speaking, the fibrous stack can be pre-impregnated with a polymer when it is deposited on the form. According to a variant, the fibrous stack can be deposited on the form in the dry state and then the polymer introduced into its porosity by implementing a technique known per se, such as a resin transfer molding technique, for example.

[0049] The manufacture of the precursor of the second part continues with a consolidation step E20 during which the precursor in composite material densified by the polymer becomes rigid.

[0050] During step E20, a partial curing of the polymer is carried out to obtain the consolidated precursor. The thermosetting polymer can be an epoxy or a bismaleimide (BMI). The partial curing uses a controlled temperature and duration which depend on the polymer used to obtain the desired polymerization rate. By way of non-limiting example, the second reinforcement impregnated with the thermosetting polymer can undergo a partial curing at a temperature between 140°C and 200°C for a duration between 30 minutes and 2 hours. It will be noted that, in general, the impregnated stack can be positioned in a mold to be brought to the desired shape during the partial curing. The partial curing can be carried out with the application of compaction pressure, for example by placing it in an autoclave or by drawing a vacuum. According to a variant, no compaction pressure is applied to the stack.

[0051] After the partial baking step, the shape on which the stack was obtained in step E10 can be removed or eliminated by techniques known per se such as dissolution by a suitable solvent. This gives a precursor of the second part of consolidated hollow form comprising the second reinforcement densified by the partially cured thermosetting polymer. The precursor thus defines a shape corresponding to the internal volume V of the part 1 to be obtained (see figure 2).

[0052] The first reinforcement is, for its part, obtained by implementing a step E12 by initially forming a fiber blank by three-dimensional weaving of first threads with second threads, for example by means of a Jacquard type loom on which a bundle of weft threads has been arranged in a plurality of layers, the weft threads being connected by warp threads. By "three-dimensional weaving" or "3D weaving", is meant a fabric in which at least some of the warp threads connect weft threads on several weft layers. It will be noted, however, that, in the context of the invention, the first threads may be warp threads and the second threads the weft threads or vice versa, the roles between the warp and weft threads being interchangeable. The weave of the first reinforcement may for example be an "interlock" weave, other weaves being nevertheless possible.An interlock weave is understood to mean a weave in which each layer of warp yarns binds together several layers of weft yarns with all the yarns of the same warp column having the same movement in the plane of the weave. When weaving the fiber blank, a decoupling is carried out between two successive layers of second yarns in a decoupling zone. This decoupling makes it possible to define two decoupling fiber portions that are not woven together in the decoupling zone and that can be separated from each other. In particular, in the decoupling zone, no layer of yarns of a first fiber portion is woven with a layer of yarns of a second fiber portion. In the decoupling zone, no yarn connects by weaving a layer of yarns of a first portion with a layer of yarns of a second portion. The decoupling fiber portions are each obtained by three-dimensional weaving.

[0053] Step E30 is then carried out in which the consolidated precursor is introduced into the debonding zone of the blank. This produces an assembly in which the precursor is inserted inside the internal cavity defined by the first reinforcement and gives its shape to the latter. The precursor is introduced between the debonded fibrous portions of the first reinforcement.

[0054] The process continues with the densification of the first reinforcement and the joining of the precursor to the matrix densifying the first reinforcement.

[0055] During step E40, the previously obtained assembly can be positioned in an injection tool defining a molding cavity having the external shape of the part to be produced and in which the assembly is held. A compaction pressure can or not be applied to the whole in the molding cavity. A thermosetting resin can then be injected so as to impregnate the first reinforcement. This case corresponds to an introduction of the thermosetting resin by a resin transfer molding technique.

[0056] A final curing is then carried out by maintaining the assembly in the molding cavity which allows, according to this example, the co-curing of the thermosetting resin with the partially cured polymer. The part is thus obtained comprising the first and second parts secured by the creation of covalent bonds between the polymer and the thermosetting resin (step E50). The person skilled in the art will choose a thermosetting resin compatible with the polymer by being identical to the latter or distinct, and in the latter case having a curing temperature range compatible with that of the polymer and a chemical compatibility allowing the creation of covalent bonds during the co-curing. The polymer and the resin can be fully polymerized following the final curing.A spar secured to the foot part and extending it can be introduced into the internal volume before placing it in the molding cavity and glued using an adhesive during the final cooking.

[0057] After implementing step E50, a part 1 of the type illustrated in Figure 1 is obtained, for which the second part from the precursor remains in the part which is mounted on the aircraft engine.

[0058] The expression "between ... and ..." must be understood as including the limits.

Claims

Claims

1. Hollow blade (1; 21) or hollow propeller blade (1; 11) made of organic matrix composite material, comprising (i) a first composite part (3) having a surface (SE 3 ) external defining an aerodynamic profile and comprising a first fibrous reinforcement obtained by three-dimensional weaving, and (ii) a second hollow composite part (5), located inside the first part and secured to a surface (SI 3 ) internal to the first part, the second part comprising a second fibrous reinforcement comprising a fibrous stack (51; 52; 53) of at least (a) a first layer (151) of unidirectional fibers oriented with a first angle (oj of between -65° and -25° relative to a radial direction (DR) of the blade or propeller blade, and (b) a second layer (251) of unidirectional fibers oriented with a second angle (a 2) between +25° and +65° relative to the radial direction.

2. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to claim 1, in which the first angle (a 1 is between -55° and -35° relative to the radial direction (DR), and the second angle (a 2 ) is between +35° and +55° relative to the radial direction.

3. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to claim 1, in which the first angle (oj is between -65° and -55° relative to the radial direction (DR), and the second angle (a 2 ) is between +55° and +65° relative to the radial direction.

4. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to any one of claims 1 to 3, in which the fibrous stack (52; 53) further comprises (c) a third layer (451) of unidirectional fibers oriented at a third angle (a 4 ) between -15° and +15° relative to the radial direction.

5. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to claim 4, in which the third angle (o 4 ) is between -5° and +5° relative to the radial direction.

6. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to claim 4 or 5, in which the fibrous stack (52; 53) further comprises (d) a fourth layer (351) of unidirectional fibers oriented at a fourth angle (o 3 ) between +75° and +105° relative to the radial direction (DR).

7. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to claim 6, in which the fibrous stack (52; 53) is quasi-isotropic.

8. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to any one of claims 1 to 7, in which the fibrous stack (53) is formed by repeating a plurality of units (U1; U2) each comprising a superposition of the first (151) and second (251) layers, in particular added to the third (451) layer and, more particularly still, to the fourth (351) layer.

9. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to any one of claims 1 to 8, in which the fibrous stack (51; 52; 53) is braided.

10. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to any one of claims 1 to 9, in which the second part (5) has a surface (SI 5) internal delimiting an internal volume (V) of the blade or propeller blade which has a roughness Ra less than or equal to 3.2 pm.

11. An unducted fan (100) for mounting on an aircraft, comprising a hub comprising attachment portions, and a plurality of propeller blades (11) according to any one of claims 1 to 10 mounted on the attachment portions.

12. A ducted fan (211) for mounting on an aircraft, comprising a hub comprising attachment portions, and a plurality of blades (21) according to any one of claims 1 to 10 mounted on the attachment portions.

13. A method of manufacturing a hollow blade (1; 21) or a hollow propeller blade (1; 11) according to any one of claims 1 to 10, comprising: - obtaining (E30) an assembly comprising (i) the first fibrous reinforcement defining an internal cavity, and (ii) a precursor of the second hollow-shaped part consolidated and comprising the second reinforcement densified by a partially cooked thermosetting polymer, the precursor being located inside the internal cavity and giving its shape to the first reinforcement, - the introduction (E40) of a thermosetting resin into a porosity of the first reinforcement after obtaining the assembly, and - co-cooking (E50) of the thermosetting resin thus introduced with the polymer.

14. The method of claim 13, wherein the resin is introduced into the porosity of the first reinforcement by resin transfer molding.

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