Patent Application
20230128247
The present invention relates to a resistive skin element for an acoustic panel intended for an aircraft, in particular a transport airplane.
It is known that, on an aircraft, for example on a transport airplane, significant noise is often generated, notably by the propulsive assemblies or jet engines of the aircraft. To reduce the noise effect produced by the jet engines of the aircraft, it is known practice to provide, in particular on the nacelles of the jet engines, walls provided with panels offering good acoustic absorption. Usually, an acoustic attenuation panel, hereinafter called acoustic panel, generally comprises an acoustic structure. This acoustic structure often comprises a cellular structure, in particular a honeycomb structure, and is provided on both of its faces, respectively, with an acoustic skin also called resistive skin or resistive layer that is perforated, and with a backing skin or backing layer that is not perforated. The acoustic panel is arranged so that the acoustic skin is situated in proximity to the noise source, notably upstream and/or downstream of the fan in the case of an aircraft jet engine, to provide effective absorption of the noise generated upstream and downstream of the fan.
Generally, the resistive skin is thermoformed before being perforated to satisfy the acoustic demands. To satisfy the aerodynamic demands, in order to have minimal drag, the size of the perforations to be produced is generally between 0.4 mm and 1 mm, preferably less than 0.5 mm. This perforation size can be a problem on an industrial scale because of the number of perforations to be produced and the drilling rate. This can have an influence on the quality of the perforations.
An aspect of the invention relates to a resistive skin element for an acoustic panel intended for an aircraft, in particular a transport airplane, which mitigates this drawback.
According to an embodiment of the invention, the resistive skin element comprises:
a first ply comprising at least:
Thus, by virtue of the wire mesh, it is possible to produce perforations of sizes greater than that of the prior art in order to obtain a low drag similar to that obtained with perforations of smaller size, while obtaining a desired acoustic permeability and mechanical demand.
According to one embodiment, the first ply comprises a second film made of PEI applied onto a second face of the layer made of C/PEAK.
According to another embodiment, the first layer made of PEI of the second ply corresponds to a first film made of PEI, the second ply further comprises a layer made of C/PEAK having a first face onto which is applied the first film made of PEI of the second ply such that the first film made of PEI of the second ply faces the wire mesh.
According to another embodiment, the second ply further comprises a second film made of PEI applied onto a second face of the layer made of C/PEAK of the second ply.
According to another embodiment, the first layer made of PEI of the second ply corresponds to a layer made of C/PEI.
According to another embodiment, the first layer made of PEI of the second ply corresponds to a first film made of PEI, the second ply further comprising a layer made of C/PEI and a second film made of PEI, the layer made of C/PEI being sandwiched between the first film made of PEI and the second film made of PEI.
The invention also relates to an acoustic panel intended for an aircraft. According to an embodiment of the invention, the acoustic panel comprises:
The invention also relates to a propulsive device for an aircraft.
According to an embodiment of the invention, the propulsive device comprises at least one acoustic panel as specified above.
The invention also relates to an aircraft comprising at least one acoustic panel as specified above.
The invention also relates to a method for manufacturing a resistive skin element for an acoustic panel intended for an aircraft.
According to an aspect of the invention, the method comprises a first series of steps for forming a first ply, the first series of steps comprising at least:
According to one embodiment, the first series of steps further comprises:
According to another embodiment, the second series of steps further comprises:
According to another embodiment, the second series of steps further comprises:
According to another embodiment, the first layer made of PEI of the second ply corresponds to a layer made of C/PEI.
According to another embodiment, the second series of steps further comprises:
The attached figures will give a good understanding of how the invention can be produced. In these figures, identical references denote similar elements.
An acoustic panel 21 for a propulsive device P is usually of a generally tapered form. The resistive skin 17 also has a generally tapered form as represented in
The resistive skin element 1 comprises two thermoplastic materials having different melting points, notably a resin from the family of carbon fiber-reinforced polyaryletherketones and a resin of polyetherimide optionally reinforced with carbon fibers. The family of polyaryletherketones comprises the polyetheretherketone resin PEEK, the polyetherketoneketone resin PEKK, etc. The carbon fibers can be replaced by glass fibers or a mixture of carbon fibers and of glass fibers. Hereinafter in the description, only carbon fibers will be mentioned, but it is understood that these carbon fibers can therefore be replaced by glass fibers or a mixture of carbon fibers and of glass fibers.
Hereinafter in the description, the resin from the family of the carbon fiber-reinforced polyaryletherketones and the carbon fiber-reinforced polyetherimide resin will be called C/PEAK and C/PEI, respectively.
Likewise, the resin from the family of the polyaryletherketones and the polyetherimide resin will be called PEAK and PEI, respectively.
PEI is miscible in PEAK at a consolidation temperature of between 290° C. and 300° C. The melting of the PEAK occurs at a temperature of 342° C. with a consolidation temperature of between 390° C. and 400° C.
The resistive skin element 1 comprises a ply N1, a ply N2 and a wire mesh 6.
As represented in
The ply N2 corresponds to a ply N2 with openings comprising at least one layer made of PEI 5. The ply N2 with openings has openings 8 configured so that the ply N2 does not block the perforations 7 of the ply N1.
The wire mesh 6 is sandwiched between the ply N1 and the ply N2 in such a way that the film made of PEI 3 of the ply N1 faces the wire mesh 6.
The wire mesh 6 can comprise several woven parts (or woven patches) in order to facilitate the placement of the wire mesh 6 on the ply N1 when said ply N1 is consolidated. The set of the woven parts then forms the wire mesh 6. The woven parts can be joined edge-to-edge or by overlaying of the edges in joining zones. In order to form the wire mesh 6, the joining zones between the woven parts are sandwiched between the ply N1 and the ply N2 in such a way that the perforations 7 of the ply N1 and the openings 8 of the ply N2 are not in line with said joining zones of the wire mesh 6.
The wire mesh 6 can be made of metal. The wire mesh 6 can also be made of polymer. By way of example, the wire mesh 6 can be made of PEAK. Preferably, the polymer has a melting point greater than that of the C/PEI.
According to an embodiment represented in
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According to a preferred embodiment represented in
The film made of PEI 5 of the ply N2 allows a good assembly with the ply N1 comprising the layer made of C/PEAK 2 at the time of consolidation.
The invention also relates to an acoustic panel 21 intended for an aircraft AC.
The acoustic panel 21 comprises at least one resistive skin element 1 according to the invention. The resistive skin element or elements 1 are assembled to form the resistive skin 17 of the acoustic panel 21.
The acoustic panel further comprises a band 18 applied onto the ply N2, an adhesive layer 19 applied onto the band 18 and a honeycomb layer 20 applied onto the adhesive layer 19. The band 18 is applied onto the parts of the ply N2 without blocking the openings 8 of the ply N2.
The band 18 can be made of a thermosettable material.
In a nonlimiting manner, the films made of PEI 3, 9, 13 and 16 have a thickness lying within a range of between 25 μm and 150 μm, preferably within a range between 80 μm and 100 μm, advantageously equal to 90 μm. Likewise, in the embodiments (
The invention also relates to a propulsive device P for an aircraft AC. The propulsive device P comprises at least one acoustic panel 21 according to the invention.
The invention also relates to an aircraft AC comprising at least one acoustic panel 21 according to the invention.
The invention also relates to a method for manufacturing the resistive skin element 1 for an acoustic panel 21 intended for an aircraft AC.
As represented in
The series of steps S1 comprises at least:
The perforations 7 have a size which depends on an acoustic permeability desired for the acoustic panel 21 and/or on desired mechanical performance levels.
The consolidation and shaping step E14 can be performed, for example in a press, at a temperature of between 390° C. and 400° C. The consolidation can comprise roll-bonding in addition to the consolidation.
The ply N1 comprising the layer made of C/PEAK is therefore preformed, consolidated and perforated in advance. The three operations can be performed in parallel, which creates a time saving in the manufacturing of the resistive skin element 1.
The series of steps S2 comprises at least one step E21 of providing the layer made of unconsolidated PEI 5. The layer made of PEI 5 comprises openings 8.
The series of steps S3 comprises at least:
The application step E32 makes it possible to shape the wire mesh 6 on the ply N1 which is already consolidated. This makes it possible to facilitate the application of the wire mesh 6 for its encapsulation between the ply N1 and the ply N2.
The consolidation can comprise a roll-bonding in addition to the consolidation. The consolidation step E34 can be performed, for example in a press, at a temperature of between 290° C. and 300° C. to allow co-consolidation between the ply N1 and the ply N2. A pressure of between 1 bar and 100 bar can be exerted to obtain an adequate quality of the resistive skin element 1. The wire mesh 6 is thus encapsulated between the ply N1 and the ply N2 after the consolidation of the consolidation step E34. Since the melting point of the PEAK is greater than the melting point of the PEI, the consolidation at a temperature of between 290° C. and 300° C. does not affect the ply N1 which is already consolidated. Thus, this makes it possible to maintain a geometrical form which ensures the acoustic properties desired for the resistive skin element 1, because the ply N1 comprising the layer made of C/PEAK is not deconsolidated by the consolidation step E34. Through the use of C/PEAK, the layer made of C/PEAK does not migrate toward the perforations 7 that have already been made. Furthermore, there is also not any deformation of the ply N1, or degradation of the material from which the ply N1 is manufactured.
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The ply N2 can be produced beforehand by an injection method or by a hand or contact lay-up molding method before being applied onto the wire mesh 6. It can also be performed by surjection directly onto the wire mesh 6 with the PEI or the C/PEI in order to shape the ply N2 directly on the already consolidated ply N1.
The invention also relates to a method for manufacturing an acoustic panel 21 intended for an aircraft AC.
As represented in
While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2111314 | Oct 2021 | FR | national |
