Classifications

• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/20—Layered products comprising a layer of metal comprising aluminium or copper
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
  • B32B3/10—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material
  • B32B3/12—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D33/00—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for
  • B64D33/02—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D33/00—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for
  • B64D33/02—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes
  • B64D2033/0206—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes comprising noise reduction means, e.g. acoustic liners
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D33/00—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for
  • B64D33/02—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes
  • B64D2033/0266—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes specially adapted for particular type of power plants
  • B64D2033/0286—Arrangements in aircraft of power plant parts or auxiliaries not otherwise provided for of combustion air intakes specially adapted for particular type of power plants for turbofan engines
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
  • Y10T156/10—Methods of surface bonding and/or assembly therefor

Definitions

• the present invention relates to a method of manufacturing an acoustic panel for an aircraft nacelle.
• Aircraft turbojets generate significant noise pollution. There is a strong demand to reduce this pollution, especially as the turbojets used become more and more powerful.
• the design of the nacelle surrounding a turbojet contributes to a large extent to the reduction of this noise pollution.
• nacelles are equipped with acoustic panels to reduce the noise generated by jet engines.
• Acoustic panels are sandwich structures well known for absorbing these noises. These panels usually comprise one or more layers of honeycomb core structure
• acoustic a perforated skin permeable to air
• the acoustic panel may further comprise several layers of noise-trapping structure called “sound absorption structures", between which there is a perforated m ulti skin called “septum”.
• the acoustic absorption structure may be a cellular core structure containing a multitude of honeycomb cells.
• the septum is generally bonded between the structures trapping the noise by polymerization during the assembly / gluing phase of the panel.
• the acoustic panel is then assembled by arranging the different skins and layers then glued on a mold to the required shape.
• the assembly is baked in an oven so as to clamp the layers and to cure the adhesives.
• Such panels constitute acoustic resonators suitable for
• acoustic panels typically include acoustic skin and solid skin made of composite materials. Acoustic panels are known in which the acoustic skin is already perforated before being assembled with the acoustic absorption structure. It is thus possible to cite acoustic skins such as those described in patent application FR09 / 05605, the acoustic openings of which are formed as soon as the skin is made.
• the perforated acoustic skin made of a composite material, of carbon type is in contact with the metallic sound absorption structure, then a galvanic corrosion phenomenon is created in which the acoustic carbon composite skin plays the role of cathode and the metal sound absorption structure plays the role of anode. This causes a deterioration of the metal sound absorption structure and, therefore, the acoustic panel.
• An object of the present invention is therefore to provide an acoustic panel comprising an acoustic skin having, prior to its installation, acoustic openings and a metal absorption structure, said panel being protected from the phenomenon of galvanic corrosion.
• the subject of the invention is a method of manufacturing an acoustic panel for a nacelle of an aircraft, said panel comprising a metallic acoustic absorption structure and an acoustic skin presenting a multitude of acoustic openings,
• said method comprising: a step A in which a layer containing a polymerizable insulating material is formed around the acoustic openings of the acoustic skin, said insulating material being configured to protect the acoustic absorption structure from corrosion;
• the panel obtained by the method of the invention therefore comprises an acoustic skin having before its installation acoustic openings which are not obstructed during the production of the acoustic panel.
• Said skin is not in contact with the metallic acoustic absorption structure but with the layer of polymerizable insulating material which protects the acoustic asbestos structure from corrosion without the laying of said insulating material causing clogging of the openings. acoustic.
• the method of the invention makes it possible to provide an acoustic panel without having a step of perforating the acoustic skin.
• the invention then makes it possible in a simple manner to provide a protection against galvanic corrosion by means of the polymerizable insulating material interposed between the acoustic skin and the acoustic absorption structure without increasing the mass of the acoustic panel, or increasing the number of manufacturing steps of said panel.
• the panel of the invention comprises one or more of the following optional features considered alone or according to all the possible combinations:
• step A the layer of insulating material deposited on the acoustic skin is heated
• the heating temperature is between 50 ° C. and 200 ° C .
• step A depositing a discontinuous layer of insulating material by spraying on the acoustic skin said insulating material so as to form a layer of insulating material around the acoustic openings;
• the layer of insulating material is formed around the acoustic openings by first depositing a continuous layer of insulating material over the entire surface of the acoustic skin and then releasing the acoustic openings thus clogged by heating and / or by blowing through said acoustic openings;
• the polymerizable insulating material is chosen from thermosetting materials based on epoxide, polyimide or bismaleimide, and thermoplastic materials;
• step B the polymerization is carried out at a temperature greater than or equal to the ambient temperature and / or at a pressure greater than or equal to the ambient pressure, in an autoclave or in an oven;
• the acoustic skin is solidified by heating at a temperature of between 100 ° C. and 250 ° C. and at a pressure of between 2 bars and 8 bars;
• step B the acoustic skin and the layer of insulating material formed on said skin during step (A) are substantially simultaneously identified by polymerization;
• the layer of adhesive material is deposited by spraying around the acoustic openings
• step A depositing a layer consisting of a first ply of insulating material surmounted by a second ply of adhesive material, said first ply and second ply being configured to be polymerized during step B;
• the polymerization speed of the adhesive material is lower than that of the insulating material
• thermosetting materials based on epoxide, polyimide or bismaleimide, and thermosetting materials
• the acoustic skin comprises a plurality of stacked layers of composite flat ribbons each directed by their longitudinal axis defining a direction, the longitudinal axes of the ribbons of the same layer being parallel to one another, said ribbons of said same layer being spaced apart; each other so as to present acoustic openings in the acoustic skin;
• the method of the invention comprises a step C in which the acoustic structure is fixed on the acoustic assembly obtained at the end of step B.
• FIG. 1 is a schematic cross section of a panel obtained in the context of the method of the invention.
• FIG. 2 is a schematic cross section of an acoustic skin already comprising acoustic openings and a layer of a polymerizable insulating material in one embodiment of step A of the method of the invention;
• FIG. 3 is a schematic cross-section of the layer of the polymerizable insulating material mounted on the acoustic skin at the end of step A;
• FIG. 4 is a schematic cross section of the acoustic skin attached to the layer of the insulating material of FIG. 3 at the end of an embodiment of step B of the process of the invention;
• FIG. 5 is a schematic cross-section of the acoustic skin attached to the layer of insulating material of FIG. 4 comprising a layer of an adhesive material;
• FIG. 6 is a schematic cross-section of the embodiment of FIG. 5 at the end of the crosslinking of the layer of adhesive material;
• FIG. 7 is a schematic cross section of an embodiment of a part of an acoustic panel obtained at the end of the method of the invention according to the embodiments of FIGS. 1 to 6;
• Figures 8 to 10 are schematic cross sections of a variant of the embodiment of Figures 3 to 6;
• FIGS. 1 1 to 13 are schematic cross sections of another embodiment of the embodiment of Figures 3 to 6.
• the method of the invention aims at producing an acoustic panel 1 for a nacelle of an aircraft (not shown) which comprises an acoustic skin 3 having acoustic openings 5, said skin 3 being fixed to a metallic sound absorption structure 7, itself fixed to a solid skin 9.
• the acoustic skin 3 used in the method of the invention is an acoustic skin having acoustic openings 5 before the laying of said skin 3 on the acoustic absorption structure 7 in the acoustic panel 1.
• the acoustic skin 3 may have any type of acoustic openings 5.
• the acoustic openings 5 may have any shape, as indicated above.
• the acoustic openings 5 may have a diameter of between 0.5 mm and 3.0 mm.
• the acoustic skin may be of the type comprising a plurality of stacked layers of composite flat ribbons each directed by their longitudinal axis defining a direction, the longitudinal axes of the ribbons of the same layer being parallel to each other, said ribbons of said same layer being spaced from each other so as to have acoustic openings 5 in the acoustic skin 3, such as the acoustic skins described in the application FR09 / 05605.
• the resin prepreg fiber ribbons are not joined edge to edge or overlap, but have a spacing therebetween.
• the ribbons of the same layer are not in contact with each other.
• the alternation of the layers is performed so as to obtain acoustic openings 5 in which the noise is able to penetrate.
• the acoustic absorption structure 7 may be, for example, a honeycomb core structure (see FIG. 1).
• the latter has a plurality of walls 1 1 forming the cells 13 which are configured to trap the noise.
• the acoustic absorption structure 7 is made of a metallic material, such as aluminum.
• the solid skin 9 is typically made by superimposing a multitude of composite plies, in particular composed of carbon fiber fabric pre-impregnated with resin, in particular of the epoxide, polyimide or bismaleimide type.
• the solid skin 9 does not have an acoustic opening 5.
• the method of the invention comprises: a step A in which a layer 21 containing a polymerizable insulating material is formed around acoustic openings 5 of the acoustic skin, said insulating material being configured to protect the acoustic absorption structure 7 from corrosion, by ensuring a physical separation between the acoustic skin 3 and the sound absorption structure 7;
• the method of the invention thus makes it possible to use an acoustic skin 3 having acoustic openings 5 before its installation and its fixing in the acoustic panel 1.
• the method of the invention makes it possible to provide a decorative panel 1 without having a step of perforating the acoustic skin 3 because the acoustic openings 5 of the latter are not obstructed during the manufacture of said panel 1.
• the invention then makes it possible in a simple manner to provide protection against galvanic corrosion of the acoustic absorption structure 7 by means of the polymerizable insulating material without weighing the mass of the acoustic panel 1, nor increasing the number of manufacturing steps. said panel 1.
• the layer of insulating material 21 has a thickness of between 0.04 mm and 0.32 mm.
• the polymerizable insulating material is a material chosen from thermosetting materials based on epoxide, polyimide or bismaleimide, and thermoplastic materials.
• the layer of insulating material 21 deposited on the acoustic skin 3 is heated.
• the heating of this layer 21 makes it possible to initiate a prepolymerization sufficient to confer a good cohesion of said layer. or even a softening.
• the manipulation of the assembly formed by the acoustic skin 5 surmounted by the layer of insulating material 21 is easier.
• the heating temperature is between 50 ° C and 200 ° C. It is also possible that the insulating material can prepolymerize, that is, initiate polymerization, at room temperature.
• step A a discontinuous layer of insulating material 21 is deposited by spraying on the skin acoustically 3 said insulating material so as to form a layer of insulating material 21 around the acoustic openings 5.
• the formation of the layer of insulating material 21 around the acoustic openings 5 is made in a single step. pulverized material is fixed on the material of the acoustic skin 3 and therefore around the acoustic openings 5.
• the layer of insulating material 21 is formed around the acoustic openings 5 by first depositing a continuous layer of insulating material 21 on the entire surface of the acoustic skin 3 and then disengaging the acoustic openings 7 thus obstructed by heating and / or blowing through said acoustic openings 7.
• the layer of insulating material 21 is advantageously deposited on the face 23 of the acoustic skin 3 intended to be fixed on the acoustic absorption structure 7.
• the heating and / or blowing allows to generate a piercing of the material of the layer of insulating material 21 which obstructs the acoustic openings 5.
• the material then comes to press on the edges of the acoustic openings 5. Therefore , the layer of insulating material 21 is formed around each acoustic opening 5 without obstructing the latter.
• the heating temperature can be between 50 ° C and
• the blowing can be carried out by means of a nozzle with manual or automated movement.
• the removal of the layer of continuous insulating material 21 can be carried out manually or automatically, for example by means of rollers.
• the acoustic skin 3 used in this embodiment can be solidified by polymerizing it before adding the layer of insulating material 21, namely before step A, which makes it easier to apply the layer of material. insulation 21.
• the polymerization typically involves heating said skin 3 to a temperature between 100 ° C and 250 ° C under a pressure between 2bar and 8bar.
• the acoustic skin 3 is not polymerized prior to step A, namely before the removal of the layer of insulating material 21, but during step B with the layer of insulating material 21 obtained at the end of step A.
• the acoustic skin 3 and the layer of insulating material 21 can be polymerized substantially simultaneously.
• the number of steps of the process of the invention is thus limited.
• the layer of insulating material 21 obstructs the acoustic openings 5 of the acoustic skin.
• the layer of insulating material 21 is deposited only on the material of the acoustic skin 3 and no longer obstructs the acoustic openings 5.
• the layer 21 of insulating material has acoustic openings 25 of diameter substantially equal to or greater than that of the acoustic openings 5 of the acoustic skin.
• the diameter of the acoustic openings 25 of said layer is between 0.5mm and 3.0mm.
• step B the layer of insulating material 21 fixed to said skin 3 and optionally the acoustic skin 3 is solidified by polymerization.
• the polymerization then consists in heating to a temperature of between 100 ° C. and 250 ° C. under a pressure of between 2 bars and 8 bars.
• the method may then comprise an additional step C in which the acoustic structure 7 is fixed on the acoustic assembly obtained at the end of step B.
• an additional step C in which the acoustic structure 7 is fixed on the acoustic assembly obtained at the end of step B.
• the adhesive material thus makes it possible to bond the layer of insulating material 21 to the metal absorption structure 7.
• the adhesive material may be chosen from thermosetting materials based on epoxide, polyimide or bismaleimide, and thermosetting materials. .
• the method of the invention may comprise a step in which a layer of an adhesive material is formed on the layer of insulating material 21 around the acoustic openings 25; 35 to preserve these.
• the layer of adhesive material 31 has a thickness of between 0.04mm and 0.32mm.
• the method of the invention may comprise a step in which a layer of an adhesive material 31 is deposited on the layer of insulating material 21.
• Said layer of insulating material 21 may or may not already be polymerized according to step B.
• the layer of adhesive material may be deposited by spraying around the acoustic openings 5, 25.
• a continuous layer of adhesive material 31 can be deposited on the layer of insulating material 21.
• the layer of adhesive material 31 then obstructs the acoustic openings 5 and 25.
• the heating temperature can be between 50 ° C. and 200 ° C.
• the layer of adhesive material 31 has acoustic openings 35 extending from the acoustic openings 5 and 25.
• the diameter of said acoustic openings 35 is typically substantially equal to or greater than the diameter of the acoustic openings 5 and 25, in particular between 0.5 mm and 3.0 mm.
• the acoustic absorption structure 7 is placed on the layer of adhesive material 31.
• the assembly can then be heated to a temperature of between 100 ° C. and 250 ° C. at a pressure of between 2 bars and 4 bars so as to polymerize the layer of adhesive material in order to fix the layer of adhesive material 31 by gluing on the 7.
• the layer of adhesive material 31 forms a meniscus at the end of the walls 1 1 of the cells in contact with the layer 31 without clogging said cells 13.
• a layer of an adhesive material 31 separate from the layer of insulating material 21 on the latter.
• the layer of adhesive material 31 and the layer of insulating material 31 do not have an acoustic opening 35 and both obstruct the acoustic openings 5 of the acoustic skin.
• the acoustic openings 25, 35 are then formed in a single step in the layers of insulating material 21 and ad hoc material 31, in particular by heating and / or blowing as indicated above.
• step B the assembly formed by the layer of insulating material 21 and the layer of adhesive material 31 (see FIG. 10) is polymerized.
• the layer of insulating material 21 and the layer of adhesive material 31 are deposited one ically on the material of the acoustic skin 3 and thus no longer obstruct the acoustic openings 5.
• the adhesive material may advantageously be slower to polymerize than the insulating material.
• the insulating material may have a higher polymerization rate than the polymerization of the adhesive material so that the adhesive material will solidify upon bonding of the sound absorbing structure 7 and not before this step. 'assembly. Indeed, if the adhesive material is in an advanced stage of the polymerization, fixing the acoustic absorption structure 7 on the layer of adhesive material 31 generates point deposits of glue which penalize the bonding and therefore the adhesion of acoustic panel 1.
• the material used may be heat-curable materials based on epoxide, polyimide or bismaleimide, and thermosetting materials.
• the acoustic structure 7 can then be placed and glued on the layer of adhesive material 31 as indicated above, the gluing being able to be carried out under heating at a temperature of between 100 ° C. and 250 ° C. and at a pressure of between 2 bars and 4 bars.
• step A it is possible to deposit a single layer 41 consisting of a first ply 42 of insulating material and a second ply 43 of adhesive material configured to be polymerized during of step B, said second fold 43 overcoming the first fold 42.
• step A the layer 41 no longer blocks the acoustic openings 5.
• the number of steps of the process of the invention is further reduced.
• the adhesive material may be slower to polymerize than the insulating material.
• the polymerization of the insulating material can be carried out by heating or at room temperature while leaving a time sufficient rest. In the case where heating is necessary, the temperature is between 50 ° C and 200 ° C.
• step B the polymerization can be carried out at a temperature greater than or equal to the ambient temperature and / or at a pressure greater than or equal to the ambient pressure, in an autoclave or in an oven.
• the polymerization can be carried out at ambient temperature or pressure.
• the polymerization may be carried out in an autoclave at a temperature and pressure substantially above ambient temperature and pressure.
• the polymerization can be carried out in an oven at a temperature substantially above room temperature and at ambient pressure.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Aviation & Aerospace Engineering (AREA)
• Soundproofing, Sound Blocking, And Sound Damping (AREA)
• Laminated Bodies (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=42732306

Family Applications (1)

Country Status (8)

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Family Cites Families (11)

• 2009
  • 2009-12-11 FR FR0905998A patent/FR2953973A1/fr not_active Withdrawn
• 2010
  • 2010-12-06 WO PCT/FR2010/052619 patent/WO2011070279A1/fr active Application Filing
  • 2010-12-06 BR BR112012011843A patent/BR112012011843A2/pt not_active IP Right Cessation
  • 2010-12-06 US US13/515,154 patent/US20120291937A1/en not_active Abandoned
  • 2010-12-06 CN CN2010800550529A patent/CN102652335A/zh active Pending
  • 2010-12-06 RU RU2012128425/28A patent/RU2012128425A/ru not_active Application Discontinuation
  • 2010-12-06 EP EP10801630A patent/EP2510514A1/de not_active Withdrawn
  • 2010-12-06 CA CA2780191A patent/CA2780191A1/fr not_active Abandoned

Non-Patent Citations (1)

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