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

Abstract

Hollow blade or hollow propeller blade made of organic matrix composite material. The present invention relates to a hollow blade (1) or hollow propeller blade (1) made of organic matrix composite material, comprising (i) a first part (3) defining an aerodynamic profile and comprising a first fibrous reinforcement obtained by three-dimensional weaving, and (ii) a second hollow part (5), located inside the first part and bonded to the first part, the second part comprising a second fibrous reinforcement comprising a fibrous stack of at least (a) a first layer of unidirectional fibers oriented between -65° and -25° with respect to a radial direction (DR) of the blade or propeller blade, and (b) a second layer of unidirectional fibers oriented between +25° and +65° with respect to the radial direction. The present invention also relates to associated manufacturing methods. Figure for the abstract: Fig. 1.

Description

Title of the invention: Hollow blade or hollow propeller blade made of organic matrix composite material technical field

[0001] The present disclosure relates to a hollow blade or hollow propeller blade made of organic matrix composite material having improved torsional performance, as well as associated manufacturing processes. Previous technique

[0002] The use of a composite material makes it possible to produce lighter turbine blades or propeller blades compared to using a metallic material. Their use contributes to optimizing the performance of turbomachines, particularly 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 the 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 achieve this is to use hollow parts made of composite material.

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

[0005] Such a technique yields satisfactory results but imposes constraints on the manufacturing process, notably maintaining a sufficiently large outlet in the final part after die formation to evacuate the fugitive material, and ensuring that this material is compatible with the pressure and temperature conditions used during die formation so as not to affect the shape of the part to be obtained. These conditions can be limiting if it is desired to form larger parts and / or parts with more complex geometries, so other solutions may be sought.

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

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

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

[0009] The present invention proposes a hollow blade or a hollow propeller blade having a hybrid fibrous reinforcement comprising, on the one hand, a three-dimensional fabric in the first part defining the aerodynamic profile and, on the other hand, a fibrous 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 formed solely by the three-dimensional fabric.

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

[0011] Such a feature makes it possible to further improve the torsional performance of the part.

[0012] In one embodiment, the first angle is between -65° and -55° with respect to the radial direction, and the second angle is between +55° and +65° with respect to the radial direction.

[0013] In one embodiment, the fiber stack further comprises (c) a third layer of unidirectional fibers oriented with a third angle between -15° and +15° with respect 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° with respect to the radial direction.

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

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

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

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

[0020] In one 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 fibrous 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 break initiation zone in the second reinforcement.

[0024] In one 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] The roughness Ra can be measured with a 3D profilometer.

[0026] This characteristic of the surface condition 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 manufacturing step of the precursor, before assembly with the first reinforcement.

[0027] The present description also relates to an unfaired fan intended to be mounted on an aircraft, comprising a hub including fastening parts, and a plurality of propeller blades as described above mounted on the fastening parts.

[0028] The present description also relates to a shrouded fan intended to be mounted on an aircraft, comprising a hub including fixing parts, and a plurality of blades as described above mounted on the fixing parts.

[0029] The present description also relates to a method for manufacturing a hollow blade or a 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 part of hollow shape consolidated and comprising the second reinforcement densified by a partially baked 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 - the co-curing 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 a holding tool 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 baking of the polymer, i.e. the polymer is incompletely polymerized. It may have a degree of polymerization greater than or equal to 80%, for example between 80% and 90%. For a given polymer, the degree of polymerization can be determined by Differential Scanning Calorimetry; "DSC"). The polymer's degree of polymerization is sufficient for the precursor to have the desired degree of stiffness. However, the polymerization is not yet complete enough to allow co-curing and thus bond the second part to the inner surface of the first part. This co-curing allows the thermosetting resin, introduced into the first reinforcement, to polymerize with the incompletely polymerized polymer. This creates covalent bonds between the polymer chains present, resulting in the bonding of the first and second parts.

[0032] The described process uses a precursor for the second part, allowing the first reinforcement to be shaped as desired. The precursor has the advantage of not needing to be removed from the densified part, thus eliminating the constraints related to the removal of fugitive inserts described above. Furthermore, the use of the rigid precursor prevents any risk of affecting the shape of the part during resin insertion.

[0033] In one 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 (Resin Transfer Molding). Those skilled in the art will recognize that other techniques can be used to introduce the resin, as will be described below. Brief description of the drawings [Fig.1] Fig.1 represents, schematically, an example of a hollow blade or hollow propeller blade according to the invention. [Fig.2] Fig.2 represents, schematically, a cross-sectional view along II-II of the part in [Fig.1]. [Fig. 3] Figure 3 represents, schematically and partially, an example of a fibrous stacking that can be implemented within the framework of the invention. [Fig.4] [Fig.4] represents, schematically and partially, another example of a fibrous stacking that can be implemented within the framework of the invention. [Fig.5] Fig.5 represents, schematically and partially, another example of fibrous stacking that can be implemented within the framework of the invention. [Fig.6] Fig.6 represents, schematically and partially, an example of an unfaired blower according to the invention. [Fig.7] Fig.7 represents, schematically and partially, an example of a shrouded blower according to the invention. [Fig.8] Fig.8 represents a succession of steps of an example of a manufacturing process for a hollow blade or a hollow propeller blade according to the invention. [Fig.9] Fig.9 represents, schematically and partially, the realization by braiding technique of a fibrous stack that can be implemented within the framework of the invention. Description of the implementation methods

[0034] The invention is now described by means of figures, which are provided 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 blade or the hollow propeller blade.

[0036] Part 1, illustrated in [Fig. 1], is made of an organic matrix composite material. It consists of two parts, 3 and 5, each made of an organic matrix composite material, which are joined together. The details for achieving this joining will be discussed later in relation to [Fig. 8], which concerns the manufacture of the part.

[0037] The first part 3 defines the external portion of the part 1. The first part 3 comprises a first fibrous reinforcement obtained by three-dimensional weaving and densified by a first organic matrix. The first part 3 has a surface SE3 that defines an aerodynamic profile, notably 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 that defines an internal volume V of the part 1 (see [Fig. 2]). The second part 5 is located inside the first part 3. The second part 5 comprises a second fibrous reinforcement consisting of a fiber stack with a controlled fiber orientation, densified by a second organic matrix. The second fibrous reinforcement may be made of the same or a different material as 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 matrix The organic matrix may be identical or different from the first organic matrix. The second part 5 has an internal SI5 surface that defines the volume V and an external SE5 surface that is in contact with an internal SI3 surface of the first part 3. The bonding between the first 3 and the second 5 parts takes place at the interface between the SE5 and SI3 surfaces, 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 that can be implemented within the framework of the invention.

[0041] Generally, the second reinforcement can consist essentially of the fiber stack. Generally, 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 stacking layers follow one another along a stacking direction that is transverse, for example normal, to the DR direction.

[0042] The example in [Fig.3] shows a first possible stacking 51 which comprises a layer 151 of unidirectional fibers oriented at an angle ai here equal to -45° with respect to the DR direction, and a layer 251 of unidirectional fibers, superimposed on layer 151, oriented at an angle a2 here equal to +45° with respect to the DR direction. Layer 251 is in contact with layer 151.

[0043] The example in [Fig. 4] shows a second possible stacking 52 which comprises unidirectional layers 151, 251 similar to those in [Fig. 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 at an angle a3 here equal to +90° with respect to the DR direction, and layer 451 is oriented at an angle a4 here equal to 0° with respect 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 [Fig. 4] corresponds to a so-called quasi-isotropic fiber stacking. When moving along the stacking direction, one passes, in this order, through layer 151, layer 251, layer 351, and layer 451.

[0044] The example in [Fig. 5] shows a third possible stacking 53 which includes a repetition of several units U1 and U2. Unit U1 is similar to the stacking illustrated in [Fig. 4] and unit U2 is symmetrical to unit U1. The stacking can continue along the stacking direction with an alternation between units U1 and U2. and U2, that is, with a second U1 unit following the U2 unit, then a second U2 unit following the second U1 unit, and so on. According to an unillustrated variant, the two-layer unit 151, 251 illustrated in [Fig. 3] could be repeated by alternating layers 151 and 251 along the stacking direction. According to another unillustrated variant, layer 351 at 90° can be omitted. The stack can thus be formed from layers 151, 251, and 451, possibly repeated as described above. In general, the stack can comprise at least 10 layers of unidirectional fibers as described above, for example, between 10 and 30 of these layers.

[0045] Part 1 can be intended for mounting on an aircraft engine. Thus, [Fig. 6] represents an open-rotor engine 100. The engine 100 comprises a nacelle for attachment to an aircraft fuselage and an open-rotor fan 111. The fan rotor 111 comprises a hub mounted for rotation relative to the nacelle and hollow propeller blades 11 as described above, which are attached to the hub. They can be mounted within a variable pitch mechanism provided in the hub. The invention is also applicable to turboprop-type architectures. The variant illustrated in [Fig. 7] relates to a shrouded aircraft engine fan 211 comprising 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 component, mounted on a shrouded or unshrouded fan rotor, has been described. However, this does not depart from the scope of the invention if the part is a static turbomachine component such as an outlet guide vane (OGV). The manufacturing process of the part will now be discussed with reference to Figures 8 and 9.

[0047] The fiber stacking is carried out with the desired fiber orientation during step E10 by implementing techniques known per se. Thus, [Fig. 9] illustrates the production of a stack 51 of the type shown in [Fig. 3] by a braiding technique. The illustrated braiding machine M comprises a plate M1 and a plurality of yarn feed spindles M3 that travel on a guide path M5. The stack 51 is braided onto a form M7 such as a mandrel. Those skilled in the art will recognize that other techniques can be used to carry out the stacking, such as filament winding.

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

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

[0050] During step E20, the polymer undergoes partial curing to obtain the consolidated precursor. The thermosetting polymer can be an epoxy or a bismaleimide (BMI). The partial curing process uses a controlled temperature and duration, which depend on the polymer used to obtain the desired degree of polymerization. By way of non-limiting example, the second reinforcement impregnated with the thermosetting polymer can undergo partial curing at a temperature between 140°C and 200°C for a duration of between 30 minutes and 2 hours. It should be noted that, generally, the impregnated stack can be positioned in a mold to be shaped as desired 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 vacuum injection. According to one embodiment, no compaction pressure is applied to the stack.

[0051] After the partial curing step, the shape on which the stacking was obtained during step E10 can be removed or eliminated by techniques known per se, such as dissolution with a suitable solvent. This yields a precursor of the second consolidated hollow-shaped part 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 [Fig. 2]).

[0052] The first reinforcement is obtained by implementing step E12, initially forming a fibrous blank by three-dimensional weaving of first yarns with second yarns, for example, using a Jacquard loom on which a bundle of weft yarns is arranged in a plurality of layers, the weft yarns being connected by warp yarns. "Three-dimensional weaving" or "3D weaving" refers to a fabric in which at least some of the warp yarns connect weft yarns over several weft layers. It should be noted, however, that within the scope of the invention, the first yarns can be warp yarns and the second yarns weft yarns, or vice versa, the roles of the warp and weft yarns being interchangeable. The weave structure of the first reinforcement can, for example, be an interlock weave, although other weaves are possible.Interlock weave refers to a weaving structure in which each layer of warp yarns interlocks several layers of weft yarns, with all yarns in the same warp column having the same movement within the plane of the weave. During the weaving of the fiber blank, an unbinding occurs between two successive layers of second yarns in an unbinding zone. This unbinding defines two unbound, unwoven fiber portions in the unbinding zone, which can be separated from each other. Specifically, in the unbinding zone, no layer of yarns of a given type... The first fibrous portion is woven with a layer of yarns from a second fibrous portion. In the unlinking zone, no yarn simultaneously weaves together a layer of yarns from the first portion with a layer of yarns from the second portion. The unlinked fibrous portions are each obtained by three-dimensional weaving.

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

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

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

[0056] A final curing is then carried out by holding the assembly in the molding cavity, which, according to this example, allows for the co-curing of the thermosetting resin with the partially cured polymer. This results in the part comprising the first and second parts joined by the formation of covalent bonds between the polymer and the thermosetting resin (step E50). A person skilled in the art will choose a thermosetting resin that is compatible with the polymer, either identical to it or different, and in the latter case, having a curing temperature range compatible with that of the polymer and chemical compatibility allowing the formation of covalent bonds during co-curing. The polymer and the resin can be fully polymerized following the final curing.A spar attached to the foot section and extending from it can be inserted into the internal volume before placement in the molding cavity and glued using an adhesive during the final firing.

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

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

Claims

Demands

1. A hollow blade (1; 21) or hollow propeller blade (1; 11) of an organic matrix composite material, comprising (i) a first composite portion (3) having an external surface (SE3) defining an aerodynamic profile and comprising a first fibrous reinforcement obtained by three-dimensional weaving, and (ii) a second hollow composite portion (5), located inside the first portion and bonded to an internal surface (SI3) of the first portion, the second portion comprising a second fibrous reinforcement comprising a fibrous stack (51; 52; 53) of at least (a) a first layer (151) of unidirectional fibers oriented at a first angle (ai) between -65° and -25° with respect to a radial direction (DR) of the blade or propeller blade, and (b) a second layer (251) of unidirectional fibers oriented at a second angle (a2) between +25° and +65° with respect to the radial direction.

2. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to claim 1, wherein the first angle (aj) is between -55° and -35° with respect to the radial direction (DR), and the second angle (a2) is between +35° and +55° with respect to the radial direction.

3. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to claim 1, wherein the first angle (ai) is between -65° and -55° with respect to the radial direction (DR), and the second angle (a2) is between +55° and +65° with respect to the radial direction.

4. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to any one of claims 1 to 3, wherein the fibrous stack (52; 53) further comprises (c) a third layer (451) of unidirectional fibers oriented with a third angle (a4) between -15° and +15° with respect to the radial direction.

5. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to claim 4, wherein the third angle (a4) is between -5° and +5° with respect to the radial direction.

6. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to claim 4 or 5, wherein the fibrous stack (52; 53) further comprises (d) a fourth layer (351) of unidirectional fibers oriented with a fourth angle (a3) ​​between +75° and +105° with respect to the radial (DR) direction.

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

8. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to any one of claims 1 to 7, wherein 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 supplemented by the third (451) layer and, more particularly still, the fourth (351) layer.

9. Hollow blade (1; 21) or hollow propeller blade (1; 11) according to any one of claims 1 to 8, wherein 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, wherein the second part (5) has an internal surface (SI5) 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. Unfaired blower (100) for mounting on an aircraft, comprising a hub including mounting parts, and a plurality of propeller blades (11) according to any one of claims 1 to 10 mounted on the mounting parts.

12. A shrouded blower (211) for mounting on an aircraft, comprising a hub including mounting parts, and a plurality of blades (21) according to any one of claims 1 to 10 mounted on the mounting parts.

13. A method for 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 cured thermosetting polymer, the precursor being located inside the internal cavity and giving its shape to the first reinforcement, - introducing (E40) a thermosetting resin into a porosity of the first reinforcement after obtaining the assembly, and - co-curing (E50) the thermosetting resin thus introduced with the polymer.

14. A method according to claim 13, wherein the resin is introduced in the porosity of the first reinforcement by resin transfer molding.

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