METHOD FOR MANUFACTURING A COMPOSITE PANEL WITH REINFORCED ZONE AND CORRESPONDING COMPOSITE PANEL

Abstract

The invention relates to a method for manufacturing a composite panel (16) for an aircraft turbomachine, the method comprising the following steps: - production of a first skin (17) in a composite material comprising a fibrous reinforcement densified by a first polymer matrix, - production of at least one reinforced zone (15), intended to form a portion of a core (19), from the first skin (17) by additive manufacturing, the reinforced zone (15) being made of a thermoplastic material, - application of at least one main zone (20) with a honeycomb structure, intended to form a portion of the core (19), onto the first skin (17) and adjacent to the reinforced zone (15), - production of a second skin (18) in a composite material comprising a fibrous reinforcement densified by a second polymer matrix, onto the core (19) and at least a portion of the reinforced zone (15). Figure for the abstract: Fig. 5

Description

Title of the invention: METHOD FOR MANUFACTURING A COMPOSITE PANEL WITH A REINFORCED ZONE AND A CORRESPONDING COMPOSITE PANEL Technical field of the invention

[0001] The present invention relates to the aeronautical field. It relates in particular to a method for manufacturing a composite panel for the production of a turbomachine nacelle and the corresponding composite panel. Technological background

[0002] Aircraft turbomachinery generally comprises nacelles equipped with multifunctional panels. These nacelles may be, for example, an internal fixed structure enclosing a gas generator of a turbomachine and / or an external structure surrounding the internal structure. The internal fixed structure is subjected to high temperatures arising from hot gas flows passing through the gas generator. The internal fixed structure is equipped with composite material panels that protect it from these high temperatures.

[0003] Composite material panels may have a sandwich structure, which allows them to attenuate the noise emitted by the components of the gas generator. In this case, the core of the sandwich structure has a honeycomb-type structure and is sandwiched between an inner and an outer skin. Each inner and outer skin is made from a fibrous reinforcement densified with a sand-cured thermosetting resin.

[0004] When the internal fixed structure carries thrust reversers, the composite material panels with the sandwich structure provide mechanical and structural support for the structure. These types of composite material panels with a sandwich structure can then provide mechanical support, acoustic attenuation, and thermal protection. The thrust reversers are mounted on the inner skin using fixing brackets such as metal fittings that are fixed to the inner skin.

[0005] Figures 1 and 2 show an example of a composite panel 01 for manufacturing an internal fixed structure. The composite panel 01 comprises several metal fittings 02, known by the English term "bumpers," which are fixed to the panel 01, only one of the metal fittings being shown. The composite panel 01 is drilled with several through holes 03 allowing the passage of screws or rivets for fixing the fittings. The through holes 03 are made at an intermediate stage of the assembly of the internal fixed structure. Each fitting A metallic element 02 is installed on the inner surface 04 of the inner skin 05. An interposition element (for example a plate or an adhesive) 06 with through holes 07 is typically mounted on the inner skin 05 between the inner surface 04 of the inner skin 05 and each metallic fitting 02. The through holes 07 of each interposition element 06 are opposite the corresponding holes in the inner skin 04.

[0006] The fixing of the fixing fittings 02 is located in a reinforced area comprising high-density honeycomb blocks. The screws are inserted into these reinforced areas, which have a greater number of cells with thicker walls to ensure mechanical strength, particularly in compression. Indeed, the honeycomb structure of the rest of the core generally has 3 / 8-inch cells and a density of approximately 67 kg / m³, which allows for acoustic performance. Outside of the areas with an acoustic function, other cell sizes and shapes are used.

[0007] The honeycomb blocks used for these reinforced areas are expensive and heavy. The reinforced areas are also enlarged to accommodate manufacturing tolerances, and the installation of these honeycomb blocks is carried out manually to ensure that the screws or rivets pass through the correct honeycomb blocks.

[0008] There is a need to resolve all or part of the aforementioned drawbacks. Summary of the invention

[0009] The objective of the present invention is to provide a simple and economical solution for easily attaching equipment to a composite panel while improving acoustic performance and reducing mass.

[0010] We achieve this objective in accordance with the invention by means of a method for manufacturing a composite panel for an aircraft turbomachine, the method comprising the following steps: - creation of a first skin in a composite material comprising a fibrous reinforcement densified by a first polymer matrix, - creation of at least one reinforced zone, intended to form a portion of a core, from the first skin by additive manufacturing, the reinforced zone being made of a thermoplastic material, - application of at least one main zone with an alveolar structure, intended to form a portion of the core, on the first skin and adjacent to the reinforced zone, - creation of a second skin in a composite material comprising a fibrous reinforcement densified by a second polymeric matrix, on the core and at least a portion of the reinforced zone.

[0011] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, the area for attaching fasteners for equipment is optimized in terms of mechanical strength and surface area. The reinforced area produced by additive manufacturing occupies a minimal surface area, which allows for an increased surface area of ​​the honeycomb core with acoustic properties. Additive manufacturing of the reinforced area allows material to be placed only where necessary and its shape to be varied according to the stresses and / or functions of the composite panel. The manufacturing of the composite panel is almost entirely automated with the integration of the reinforced area between the first and second skins during production.

[0012] The process also includes one or more of the following steps and / or features, taken alone or in combination when technically feasible:

[0013] - the polymer matrix of the first skin and / or the second skin comprises a thermoplastic resin.

[0014] - the production of the first skin and / or the second skin includes an application of several fiber strips.

[0015] - the fibrous reinforcement of the first skin and / or the second skin comprises pre-impregnated fibers.

[0016] - the reinforced area comprises an alveolar structure.

[0017] - the reinforced area is full.

[0018] - the reinforced zone is arranged in at least one intermediate zone with structure alveolar structure produced by additive manufacturing.

[0019] - the core has a density that varies between the main zone and the reinforced zone.

[0020] - Additive manufacturing includes the technique of fused filament deposition.

[0021] - the process includes a step of applying a coating to the first skin and / or under the second skin.

[0022] - the main zone of the core with an alveolar structure is arranged in the form of several blocks.

[0023] The invention also relates to a composite panel manufactured using a process as described above. The reinforced area is attached to the first and second skins via the first and second polymer matrices of the fibrous reinforcements of the first and second skins. Brief description of the figures

[0024] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent upon reading the following detailed explanatory description of given embodiments of the invention. by way of purely illustrative and non-limiting examples, with reference to the attached schematic drawings in which: - Fig. 1 illustrates a cross-section of an example of a portion of an internal fixed structure of a turbomachine according to the prior art; - Fig. 2 is a detailed view of an example of the installation of a metal fitting on a fixed structure according to the prior art; - Fig. 3 is an axial and partial cross-sectional view of an example of a turbomachine equipped with at least one internal fixed structure provided with a fastening means according to the invention; - Fig. 4 represents an example of the internal fixed structure of a turbomachine made from a composite panel according to the invention; - Fig. 5 represents, in cross-section, an example of a composite panel according to the invention; - Fig. 6 schematically represents an embodiment of a reinforced area of ​​a composite panel according to the invention; - Fig. 7 schematically represents another embodiment of at least one reinforced area of ​​a composite panel according to the invention; - Fig. 8 schematically represents another embodiment of at least one reinforced area of ​​a composite panel according to the invention; - Fig. 9 schematically represents another embodiment of at least one reinforced area of ​​a composite panel according to the invention; - Fig. 10 schematically represents another embodiment of at least one reinforced area of ​​a composite panel according to the invention; - Figure

[11] schematically represents another embodiment of at least one reinforced area of ​​a composite panel according to the invention; and - Fig. 12 illustrates a flowchart of a manufacturing process for a composite panel according to the invention. Detailed description of the invention

[0025] Figures 1 and 2 have been described above.

[0026] In this description, identical or substantially identical elements and / or elements with the same functions are represented by the same numerical references.

[0027] Figure 3 represents a turbomachine 1 intended to be mounted on an aircraft (not shown). The aircraft comprises, for example, a fuselage and two wings extending on either side of the fuselage relative to the fuselage axis. Each wing can carry at least one turbomachine.

[0028] The turbomachine 1 can be a turbojet or a turboprop.

[0029] The turbomachine 1 may include at least one propeller 2 or a fan which is either shrouded or unshrouded.

[0030] The turbomachine 1 has a longitudinal axis X, which is here the axis of rotation of the rotors of the turbomachine.

[0031] In the present invention, and more generally, the terms "upstream," "downstream," "axial," and "axially" are defined with respect to the gas flow in the turbomachine and with respect to the longitudinal axis X of the turbomachine. Similarly, the terms "radial," "radially," "internal," and "external" are defined with respect to a radial axis Z perpendicular to the longitudinal axis X.

[0032] The turbomachine 1 generally comprises, from upstream to downstream, a compressor assembly, a combustion chamber and a turbine assembly which preferably forms a gas generator 3.

[0033] The turbomachine 1 is in particular a twin-spool, twin-flow turbomachine. The compressor assembly here comprises a low-pressure compressor and a high-pressure compressor. The turbine assembly here comprises a low-pressure turbine and a high-pressure turbine. The rotors of the low-pressure compressor and the low-pressure turbine are connected, for example, by a low-pressure shaft to form a low-pressure casing. The rotors of the high-pressure compressor and the high-pressure turbine are connected, for example, by a high-pressure shaft to form a high-pressure casing.

[0034] In this embodiment, the blower 2 or propeller is mounted upstream of the compressor assembly. Advantageously, but not exclusively, the blower 2 comprises blower blades 4 which are surrounded, for example, by a blower housing 5.

[0035] The turbomachine 1 also advantageously, but not limitingly, comprises a nacelle 6, which encloses, in a non-limiting manner, certain components of the turbomachine.

[0036] Advantageously, but not limitingly, the nacelle 6 comprises an internal fixed structure 7 known by the English acronym "IFS" for "Inner Fixed Structure". The internal fixed structure 7 is advantageously arranged around at least a portion of the gas generator 3 with respect to the longitudinal axis X. The internal fixed structure 7 delimits, at least in part, with a central annular body 8, a primary flow channel 9 in which a primary flow circulates when the turbomachine 1 is in operation.

[0037] Advantageously, but not exclusively, the nacelle 6 comprises an external fixed structure 10, which is known by the English acronym "OFS" for "Outer Fixed Structure". The external fixed structure 10 is advantageously centered on the longitudinal axis X and surrounds the internal fixed structure 7. The internal fixed structure 7 and The external fixed structure 10 at least partially delimits a secondary flow channel 11 in the case of a turbojet engine. A secondary flow is intended to circulate in the secondary flow channel 11 in the case of a turbofan engine and when the turbomachine 1 is operating. The secondary flow channel 11 is arranged radially outside the primary flow channel 9.

[0038] By way of non-limitation, the external fixed structure 10 is extended upstream along the longitudinal axis X by an annular air inlet sleeve 12 which surrounds the blower housing 5.

[0039] Figure 4 shows an example of an internal fixed structure 7 for a turbomachine. In this embodiment, the internal fixed structure 7 is in the form of two half-shells centered on the longitudinal axis X. The internal fixed structure 7 advantageously extends between an upstream edge 13 and a downstream edge 14. Each half-shell comprises a portion of the upstream edge 13 and a portion of the downstream edge 14.

[0040] Advantageously, the internal fixed structure 7 is obtained from a sandwich-type composite panel. The sandwich-type structure comprises, for example, a first skin swept by the primary flow and a second skin swept by the secondary flow. A core is bonded to the first and second skins and between them. The core advantageously has a honeycomb structure of one or more predetermined densities in order to obtain different properties.

[0041] Advantageously, the internal fixed structure 7 includes reinforced areas 15 which allow the attachment of equipment such as thrust reversers using fastening elements.

[0042] Figure 5 shows a portion of an example of a composite panel 16. Advantageously, the composite panel 16 has a sandwich-type structure. The composite panel 16 can be used to create the internal fixed structure 7 as previously described or the external fixed structure 10 of the nacelle 6.

[0043] The composite panel 16 comprises a first skin 17, a second skin 18 and a core 19 arranged between the first skin 17 and the second skin 18.

[0044] The first skin 17 and the second skin 18 are preferably made of a composite material. Each first skin 17 and second skin 18 comprises a densified fibrous reinforcement in a polymer matrix.

[0045] Advantageously, the polymer matrix comprises a thermoplastic resin. The thermoplastic resin may be selected from the group comprising polyethylene, polypropylene, polyetheretherketone, polyetherketoneketone, or polyaryletherketones.

[0046] The fibrous reinforcement is achieved, for example, using several plies or layers of fibers superimposed one on top of the other. The fibers may include carbon, glass, or polyamide fibers. For example, carbon fibers can be selected from polyetherketone, polyetheretherketone, polyetherketoneketone and polyacrylonitrile fibers.

[0047] The core 19, for example, has at least one main zone 20 which is made of a honeycomb structure. The honeycomb structure of the main zone 20 reduces the noise emitted, for example, by the gas generator 3. The honeycomb structure of the main zone 20 comprises cells or alveoli whose partitions preferably have a hexagonal cross-section, known as a honeycomb structure. Of course, the partitions of the alveoli in the main zone 20 may have other shapes, such as rectangular, triangular, etc.

[0048] Advantageously, the partition of the cells has a predetermined thickness. The wall of the cells in the main zone 20 may also have a predetermined dimension.

[0049] The core 19 at the main zone 20 can be made of a metallic material such as aluminum, titanium, or steel. Aluminum is preferred because it is a lightweight material. Alternatively, the core 19 at the main zone 20 is made of a composite material. As another alternative, the core 16 can be made of a polymer material such as polyetheretherketone (without fibers and / or particles).

[0050] Advantageously, the first skin 17 includes holes 21 which each communicate with the alveoli of the core 19. The noise emanating from the gas generator 3 rises into the alveoli of the core 19 in which it is trapped.

[0051] With reference to Figures 6 and 7, the sandwich-type composite panel 16 comprises at least one reinforced zone 15 configured to accommodate fasteners. Several reinforced zones 15 are provided in the composite panel 16. Advantageously, each reinforced zone 15 is integrated and embedded in the core 19 of the composite panel 16. Each reinforced zone 15 is produced at the same time or almost at the same time as the manufacturing of the composite panel 16. However, the reinforced zone 15, the first skin 17, the second skin 18, and the core 19 are not produced using the same technique.Indeed, the first and second skins 17, 18 can be manufactured by draping layers of fibers or automatic tape draping (known by the Anglo-Saxon acronym "AFP" for Automated Fiber Placement) and at least part of the core can be made by pultrusion if it is plastic or by bonding and expansion of strips if it is metallic.

[0052] Preferably, the reinforced area or each reinforced area 15 is produced using an additive manufacturing process described later in this description.

[0053] Advantageously, but not exclusively, the reinforced zone or zones 15 have a honeycomb structure. The honeycomb structure of the reinforced zone 15 has a The configuration differs from that of the honeycomb structure of the main zone 20 of the core 19. In one embodiment, the honeycomb structure of the reinforced zone 15 has a higher density than that of the honeycomb structure of the main zone 20. Advantageously, but not exclusively, the honeycomb structure of the reinforced zone(s) 15 may have cells of different or identical shapes to those of the rest of the core. The cells of the reinforced zone 15 may have a rectangular, hexagonal, circular, or other cross-sectional shape. For example, the cells of the reinforced zone 15 may have a square shape, while the cells of the core 19 may have a hexagonal shape.

[0054] In [Fig. 6], the cells 15a of the reinforced zone 15 and the cells 20a of the main zone 20 of the web 19 have an identical, preferably hexagonal, cross-section. In this example, the size of the cells 15a of the reinforced zone 15 is smaller than that of the cells 20a of the main zone 20. Consequently, there are more cells 15a in the reinforced zone 15 than in the main zone 20 of the web 19. Therefore, the density of the cells 15a in the reinforced zone 15 is greater than that of the cells 20a in the main zone 20. The density may differ with a different wall thickness. For example, alternatively, the wall of the partitions of the cells 15a of the reinforced zone 15 has a greater thickness than that of the partitions of the cells 20a of the main zone 20 of the core 19.

[0055] Figure 7 illustrates an example of the arrangement of a web 19. The web 19 in this example comprises a main zone 20 having cavities 20a with a hexagonal cross-section. Several reinforced zones 15 are arranged within the web 19. The cavities 15a of each reinforced zone 15 also have a hexagonal cross-section. The dimensions and / or the wall thickness of the cavities 15a of each reinforced zone 15 are identical but differ from those of the cavities 20a of the main zone 20. In a non-limiting embodiment, the wall thickness of the cavities 15a of each reinforced zone 15 is greater than that of the cavities of the main zone 20, which would, for example, enhance mechanical strength.Following another embodiment example, the thickness of the partition of the cells 15a of the reinforced zone 15 is identical to that of the partition of the cells of the main zone but the cells 15a are smaller in size than the cells 20a of the main zone 20. .

[0056] As shown in [Fig. 7], an intermediate zone 22 can be arranged within the web 19. Each reinforced zone 15 is located inside the intermediate zone 22. In the case of [Fig. 7], all the reinforced zones 15 are located within the intermediate zone 22. The reinforced zones 15 are spaced apart. The intermediate zone 22 is advantageously produced by an additive manufacturing process.

[0057] Advantageously, but not exclusively, the cells 22a of the intermediate zone 22 exhibit acoustic properties. By way of example, the cells 20a of the main zone 20, the cells 22a of the intermediate zone 22, and the cells 15a of the reinforced zones 15 have the same shape, and in this case, are hexagonal.

[0058] According to one embodiment, the cells 22a of the intermediate zone 22 have a lower density than each reinforced zone 15 and a higher density than the main zone 20.

[0059] Following another embodiment, the cells 22a of the intermediate zone 22 have a partition with a thickness greater than that of the main zone.

[0060] According to one embodiment, the cells 20a of the main zone 20 have a density of between 30 kg / m³ and 80 kg / m³. By way of example, the cells 22a of the intermediate zone 22 have a density of between 80 kg / m³ and 120 kg / m³. By way of example, the cells 15a of the reinforced zone 15 have a density of between 120 kg / m³ and 400 kg / m³.

[0061] Figure 8 illustrates another embodiment of a core 19 for a composite panel 16. This embodiment differs from the previous embodiments in that the reinforced zone 15 is solid. Advantageously, several solid reinforced zones 15 are arranged in the main zone 20 of the core 19. Advantageously, each reinforced zone 15 has a circular shape. Alternatively, the reinforced zones 15 may have another shape such as rectangular, triangular, etc. In the case of circular shapes, the reinforced zones may have a diameter of approximately 10 mm. The portion of the core formed at the main zone 20 is arranged around and near the solid reinforced zones 15. Optionally, through holes are made in honeycomb structure blocks that are slid onto the solid material inserts extending from the first skin 17.

[0062] Figure 9 illustrates another embodiment of a core 19. In this embodiment, solid reinforced zones 15 are arranged within an intermediate zone 22. The solid reinforced zones 15 and the honeycomb-structured intermediate zone 22 are produced by additive manufacturing. The honeycomb-structured main zone 20 of the core 19 is arranged around the intermediate zone 22. The remainder of the core 19, formed by the main zone 20, can be attached, for example, to the intermediate zone 22 using adhesive. Alternatively, the remainder of the core 19 is in contact with the intermediate zone 22 without any means of attachment or additional material (adhesive, weld, etc.). Advantageously, but not exclusively, there is a variation in thickness between the partitions of cells 20a in the main zone 20 and cells 22a in the intermediate zone 22. For example, the thickness of the partitions varies in increasing order from the alveoli of the main zone towards the alveoli of the intermediate zone 22.

[0063] Figure 10 illustrates another embodiment of a core 19. In this embodiment, reinforced honeycomb-structured areas 15 are arranged in a first intermediate zone 22z1, which is itself arranged in a second intermediate zone 22z2. The reinforced honeycomb-structured areas 15, the first honeycomb-structured intermediate zone 22z1, and the second honeycomb-structured intermediate zone 22z2 are produced by additive manufacturing. The main honeycomb-structured area 20 of the core 19 is arranged around the second intermediate zone 22z2. The latter is arranged around the first intermediate zone 22z1. The first intermediate zone 22zl surrounds all the reinforced zones 15. As with the previous embodiment, the remainder of the core 19 formed by the main zone 20 can be fixed, for example, by means of an adhesive to the second intermediate zone 22z2.Alternatively, the remainder of the core 19 is in contact with the second intermediate zone 22z2 without any means of attachment or additional material added.

[0064] Advantageously, but not exclusively, the density of the cells varies between the main zone 20 and at least the reinforced zone 15. The density of the cells increases, for example, from the main zone 20 to the reinforced zones 15 via the intermediate zones 22z1, 22z2. In this way, the reinforced zones 15, occupying a strictly necessary space, have a greater mass than the intermediate zones 22z1, 22z2 and the main zone 20.

[0065] Figure 11 illustrates another embodiment of a core 19. This embodiment differs from that of Figure 10 in that it includes a third intermediate zone 22z3 in which the intermediate zone 22z2 is arranged. Several reinforced zones 15 are arranged within the intermediate zone 22z1, which is itself arranged within the intermediate zone 22z2. All the intermediate zones 22z1, 22z2, and 22z3, as well as the reinforced zones 15, have a honeycomb structure and are produced by additive manufacturing. There is also a variation in density from the main zone 20 to the reinforced zones 15, passing through the various intermediate zones 22z1, 22z2, and 22z3.

[0066] Advantageously, but not exclusively, the reinforced zone or zones 15 occupies the entire height of the core 19. In this way, the reinforced zone or zones 15 are in contact with the first skin 17 and the second skin 18.

[0067] In the case of a core 19 equipped with at least one intermediate zone 22, this optionally extends over the entire height of the core 19, so as to be in contact with the first and second skins 17, 18.

[0068] According to another advantageous, but not limiting, feature, the reinforced area or areas 15 (comprising cells or solids) are made of a thermoplastic material. This allows for better compatibility, particularly in terms of attachment, with at least the first matrix of the first skin 17. Advantageously, the thermoplastic material is also compatible with the second matrix of the second skin 18. The melting temperature ranges, for example, of the thermoplastic materials of the reinforced areas and the first and second matrices must be similar or coincide.

[0069] The thermoplastic material of the reinforced zone(s) 15 is advantageously chosen from the group comprising polyethylene, polypropylene, polyetheretherketone, polyetherketoneketone, polyetherimide, or polyaryletherketones. The thermoplastic material of the reinforced zone(s) 15 may be identical to that of at least the first polymer matrix. Alternatively, the thermoplastic material of the reinforced zone(s) 15 is different from at least the first polymer matrix.

[0070] We will now describe a manufacturing process 100 of a composite panel 16 for an aircraft turbomachine with reference to [Fig. 12].

[0071] The manufacturing process 100 includes a step 110 of producing a first skin 17 of composite material comprising a densified fibrous reinforcement in a first polymer matrix. The first skin 17 is produced, for example, by applying several plies or strips of fibers which are deposited onto a support (not shown). This support may be, for example, a mold having the shape of the final part to be obtained.

[0072] Preferably, the fibers in the first matrix are pre-impregnated fibers.

[0073] The first matrix preferably comprises a thermoplastic resin.

[0074] According to one embodiment, the fiber strips are deposited onto the substrate via an application element, such as at least one roller (not shown). Alternatively, the fibers can be deposited using the process known by the English acronym "FPP".

[0075] The fiber strips are then optionally compacted onto the substrate to promote, for example, their adhesion. The compaction element can be the same roller (not shown) that applies pressure to the fiber strips as they are laid down.

[0076] Advantageously, but not exclusively, the fiber strips undergo densification to further promote adhesion between the fibers. Densification can be achieved using a heating device that melts the first matrix. This device includes, for example, a furnace in which the fiber strips are placed and optionally compressed. The temperature The temperature used by the heating device is between 200°C and 500°C depending on the thermoplastic material used and the expected final properties.

[0077] According to another preferred alternative, particularly for large composite panels 16, the heating device emits radiation or heat onto the fiber strips as they are deposited onto the substrate. The heating device can be an infrared lamp or a laser. Panels 16 intended for creating fixed internal structures, for example, have a length of approximately 2 m and a width of approximately 1.50 m.

[0078] Advantageously, but not exclusively, densification and compression are carried out simultaneously so as to achieve better adhesion of the fibers to each other.

[0079] The embodiment step 110 optionally includes a substep 111 for creating holes 21 in the first skin 17. Advantageously, the holes 21 are made by mechanical drilling. For example, the mechanical drilling is carried out using a drill bit. Alternatively, the drilling can be carried out using a laser.

[0080] Advantageously, but not exclusively, the holes 21 may be circular. Alternatively, the holes 21 may have any shape provided that it allows fluidic communication with the cavities of the core 19 and is easy to manufacture. When circular, the holes 21 may have a diameter between 0.5 mm and 2 mm.

[0081] The manufacturing process 100 advantageously includes a step of producing 120 at least one reinforced area 15 by additive manufacturing on the first skin 17.

[0082] Additive manufacturing makes it possible to obtain parts of varied and complex shapes by fusing layers of material. Furthermore, additive manufacturing makes it possible to deposit the material and manufacture each reinforced area 15 only in the areas where their installation is required, which results in material savings, mass savings, cost savings, and time savings.

[0083] In particular, the material is arranged layer by layer on a manufacturing support, here the first skin 17, and each layer of material is melted or fused by an energy-generating element, solidified, and then covered by other layers of the material. The operation is repeated multiple times until the complete part is obtained.

[0084] Several additive manufacturing techniques exist, such as selective laser melting, known by the English acronym "SLM" for "Selective Laser Melting," which allows the melting of powder from the material intended to produce the final part. or selective laser sintering known by the acronym "SLS" for "Selective Laser Sintering.

[0085] Another non-limiting, and preferred, additive manufacturing technique is the fused filament deposition technique known by the English acronym "FFF" for "Fused Filament Fabrication".

[0086] The molten material is a thermoplastic as previously stated. The thermoplastic material is suitable for additive manufacturing and is compatible with the material of the first skin 17 onto which it is deposited.

[0087] During the fabrication of the first layer of material for the reinforced zone 15, it is bonded to the first skin 17 by heat welding. The material deposited on the first skin 17 has a temperature (between 200°C and 500°C) that softens or melts the thermoplastic resin of the first skin 17, thus welding at least part of the reinforced zone 15 to the first skin 17 after cooling. Furthermore, since the thermoplastic materials are compatible, the bond between the first skin 17 and the reinforced zone 15 is lighter.

[0088] All examples of the reinforced areas 15 described above are produced by the additive manufacturing technique directly on the first skin 17.

[0089] According to an advantageous, but not limiting, feature, the reinforced area 15 is made on a portion of the first skin 17 which is free of holes 21. This increases the acoustic surface area. The fixing surface area can be increased depending on the circumstances.

[0090] The process optionally includes a step of producing at least one intermediate zone 22 by additive manufacturing on the first skin 17. Advantageously, the intermediate zone 22 is manufactured at the same time as the or each reinforced zone 15.

[0091] The manufacturing process 100 advantageously includes a step 130 of applying the honeycomb-structured core 19 to the first skin 17. The core 19 is advantageously arranged adjacently with the reinforced zone(s) 15. Advantageously, but not limited to, the main zone of the core 19 is shaped to perform the acoustic function and has the same honeycomb structure over the entire surface of the composite panel 16. Preferably, the honeycomb structure of the main zone 20 has the same density over the entire surface of the composite panel. The density of the honeycomb structure of the main zone 20 is preferably on the order of 67 kg / m³, which makes it possible to obtain very good acoustic performance without adding weight to the composite panel 16.

[0092] Preferably, the core 19 is arranged in the form of several honeycomb blocks. This facilitates the installation of the core 19.

[0093] The manufacturing process 100 advantageously, but not exclusively, comprises a step 140 of producing the second skin 18 of a composite material comprising a densified fibrous reinforcement in a second polymer matrix. As with the first skin 17, the second skin 18 is produced, for example, by applying several plies or strips of fibers deposited onto a substrate. In this embodiment, the substrate is at least partly the core 19. In particular, the fiber strips are applied directly to the outward-facing external surface of the core 19.

[0094] Preferably, the fibers of the second matrix are pre-impregnated fibers. The second matrix preferably comprises a thermoplastic resin. Advantageously, the first matrix and the second matrix are identical. Alternatively, the first matrix and the second matrix are different.

[0095] The fiber strips advantageously, but not exclusively, undergo compression to compact the fibers, thereby promoting adhesion between them. The fibers can be compacted in the same way as the fibers of the first skin 17, for example by the first roller.

[0096] According to an example embodiment, the reinforced zone or each reinforced zone 15, in particular, for example, the layers of material closest to the external surface, has a predetermined temperature so as to allow bonding with the second skin 18. The temperature of the reinforced zone or each reinforced zone 15 must be greater than or equal to the melting temperature (between 200°C and 500°C) of the second matrix of the second skin 18. In this way, when the fiber strips of the fibrous reinforcement of the second skin 18 are applied, they are fixed by the thermoplastic resin which is at a suitable temperature to perform a heat seal.

[0097] The embodiment step 140 further includes, but is not limited to, a densification substep. During this densification substep, the second matrix of the second skin 18 is polymerized (between 200°C and 500°C), which densifies the thermoplastic resin of the second skin 18 and the fibers of the fibrous reinforcement. The composite panel 16 thus undergoes a second curing, for example. Simultaneously, the second matrix is ​​fixed to the reinforced area 15 during this step. Preferably, the densification is carried out using a heating device such as an oven. The temperature is between 200°C and 500°C.

[0098] Alternatively, the embodiment step 140 includes a substep of heating only the fibrous reinforcement comprising pre-impregnated fibers so as to soften the second matrix (without melting it) to polymerize it and allow adhesion to the reinforced area(s) 15. The heating can be carried out by means of a nozzle projecting an air stream or a laser, or a lamp Infrared emits radiation or heat. Heating can be carried out at a temperature between 200°C and 500°C, preferably 400°C.

[0099] According to yet another alternative, the second skin 18 is heated locally, for example, at the location where the reinforced area 15 is arranged. The heating can be carried out using a laser to soften the second matrix of the second skin 18. The temperature can also be between 200°C and 500°C.

[0100] According to an optional embodiment, the manufacturing process 100 includes a step of applying a coating to the first skin 17. This coating improves the insulation and high-temperature resistance of the first skin 17 and protects the core against oxidation. The core can oxidize, particularly when it is made of aluminum and the fibrous reinforcement includes carbon fibers. Advantageously, the coating is applied before the step of creating the holes 21 in the first skin 17. The coating preferably comprises glass fibers. Advantageously, the coating is arranged between the first skin 17 and the core 19. If this coating is added, it must be compatible with the material of the core 19, including the various areas with honeycomb or solid structures.

[0101] Advantageously, but not limitingly, a similar coating, preferably made of glass fibers, is applied to the external surface of the core 19 and of the or each reinforced area 15. In other words, the coating is disposed under the second skin 18.

[0102] The composite panel 16 obtained by such a manufacturing process comprises at least one reinforced zone attached to the first skin 17 and the second skin 18 during the manufacturing of the panel 16. The thermoplastic material of the reinforced zone 15 allows for attachment by heat welding during manufacturing. This makes it possible to enhance the acoustic properties of the panel 16 by providing reinforced zones only where necessary, thereby increasing acoustic performance. The acoustic gain at each reinforced zone can be at least 10%.

Claims

Demands

1. A method for manufacturing (100) a composite panel (16) for an aircraft turbomachine (1), the method comprising the following steps: - producing (110) a first skin (17) from a composite material comprising a fibrous reinforcement densified by a first polymer matrix, - producing (120) at least one reinforced zone (15), intended to form a portion of a core (19), from the first skin (17) by additive manufacturing, the reinforced zone (15) being made of a thermoplastic material, - applying (130) at least one main zone (20) with a honeycomb structure, intended to form a portion of the core (19), onto the first skin (17) and adjacent to the reinforced zone (15), - producing (140) a second skin (18) from a composite material comprising a fibrous reinforcement densified by a second polymer matrix, onto the core (19) and at least a portion of the zone reinforced (15).

2. A manufacturing method (100) according to claim 1, characterized in that the polymer matrix of the first skin (17) and / or the second skin (18) comprises a thermoplastic resin.

3. Manufacturing method (100) according to any one of claims 1 and 2, characterized in that the realization (110, 140) of the first skin (17) and / or the second skin (18) comprises an application of several fiber strips.

4. A manufacturing method (100) according to any one of claims 1 to 3, characterized in that the fibrous reinforcement of the first skin (17) and / or the second skin (18) comprises pre-impregnated fibers.

5. A manufacturing method (100) according to any one of claims 1 to 4, characterized in that the reinforced zone (15) comprises a honeycomb structure.

6. Manufacturing method (100) according to any one of claims 1 to 5, characterized in that the reinforced area (15) is solid.

7. Manufacturing method (100) according to any one of claims 1 to 6, characterized in that the reinforced zone (15) is arranged in at least one intermediate zone (22; 22z1, 22z2, 22z3) with a honeycomb structure produced by additive manufacturing.

8. Manufacturing method (100) according to the preceding claim, characterized in that Pâme (19) has a density which varies between the main zone (20) and the reinforced zone (15).

9. A manufacturing method (100) according to any one of claims 1 to 8, characterized in that the additive manufacturing comprises the fused filament deposition technique.

10. A manufacturing method (100) according to any one of the preceding claims, characterized in that the main area (20) of the core (19) with a honeycomb structure is shaped to perform an acoustic function and has the same density over the entire surface of the composite panel (16).

11. Composite panel (16) made according to a manufacturing process according to any one of the preceding claims, the reinforced area (15) being fixed to the first skin (17) and to the second skin (18) via the first and second polymer matrix of the fibrous reinforcements of the first skin (17) and second skin (18).

Images