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
• • 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
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49826—Assembling or joining
  • Y10T29/49947—Assembling or joining by applying separate fastener

Definitions

• the present invention relates to the field of noise reduction emitted by engines, in particular aircraft.
• These panels are typically formed of honeycomb core blocks
• Such panels are acoustic resonators capable of "trapping" the noise, and thus to reduce noise emissions towards the outside of the nacelle.
• junction areas between these blocks must be treated with particular care if one wishes to maintain a good sound absorption efficiency.
• a common technique used to connect these blocks together is to coat the adjacent edges of these blocks with an adhesive which is transforms into a foam during cooking, and which thus forms a sort of bonding web of expanded material between these edges.
• the advantage of this technique is that it allows to obtain a panel which, from a mechanical point of view, behaves as if it were formed of a single block.
• the disadvantage of this technique is that the bonding strip formed by the fired adhesive locally fills the cells of the blocks, and thus reduces the effective acoustic surface of the block; moreover, such a connecting band constitutes an acoustic impedance break which also affects the acoustic efficiency of the block.
• the present invention is intended in particular to eliminate these disadvantages.
• This object of the invention is achieved with a method for manufacturing an acoustic absorption panel, in particular for an aircraft engine nacelle, this panel being of the type comprising at least one cellular core coated on one of its faces. a so-called external skin impervious to air and on the other of its faces with a so-called internal perforated skin, this cellular core being formed by the edge-to-edge joining of a plurality of cellular core blocks, this method being remarkable in that it comprises the steps of: a) prior to the edge-to-edge joining of the cellular core blocks, opening the cells located on the edges of the blocks to be joined, and b) joining edge-to-edge and dry these blocks so that the open cells fit into each other.
• the dry (that is to say without glue) nesting of previously opened cells makes it possible to obtain a panel of which practically all the cells contribute to the attenuation of the noise.
• a panel obtained according to the present method offered a mechanical strength substantially comparable to that of the panels of the prior art.
• the method according to the invention makes it possible to obtain a panel which, although being formed of the assembly of a plurality of blocks, has an excellent acoustic absorption homogeneity on the whole of its extent and a satisfactory mechanical behavior.
• this method comprises a preliminary step consisting in selecting blocks with cellular cores of a size slightly greater than the desired final size, and a step d) in which the imbricement carried out in step b) is maintained by putting under stress these blocks: thanks to these characteristics, it is possible to hold the edges of these blocks together against one another, and thus to obtain, in fine, an acoustic panel having substantially the same mechanical characteristics as if it were formed of a single block;
• this method comprises the step c2) in which the imbricement carried out in step b) is maintained by means of fasteners such as jumpers or staples: this step, which can be implemented alone or in addition to the previous step, allows a very strong connection between the edges of the two adjacent blocks;
• this method comprises the step d) of assembling superimposed sets of blocks joined together according to any one of steps a) to c2): this method can be used for the manufacture of multilayer panels, necessary for some applications.
• the present invention also relates to an element intended to surround an engine, remarkable in that it is equipped with at least one acoustic absorption panel obtained by a method according to the above: such an element allows particularly attenuation effective noise emitted by the motor it surrounds.
• the present invention also relates to an aircraft nacelle, remarkable in that it comprises at least one element in accordance with the foregoing.
• said element may be located in the air inlet zone of said nacelle: such nacelle more particularly makes it possible to attenuate the noise emitted by the engine fan.
• FIG. 1 is a sectional view of a monolayer acoustic absorption panel according to the present invention
• FIG. 2 is a view in a layer of a bilayer acoustic absorption panel according to the present invention
• FIG. 3 is a partial schematic view from above of the junction zone of two cellular core blocks forming an acoustic absorption panel according to the present invention.
• FIG. 4 is a real view (photographed) of such a junction area.
• a monolayer acoustic absorption panel typically comprises several, and in this case, two cellular core blocks B1, B2 sandwiched between a so-called internal skin 1 and a so-called external skin 3.
• the section of the cells A1 of the block B1 may for example be smaller than that of the cells A2 of the block B2, so as to respond to acoustic and / or mechanical constraints imposed by the specifications. of the manufacturer.
• the material forming the cells of the blocks B1 and B2 may typically be a light metal alloy adapted to the aeronautical field; the material forming the inner skin 1 may be made of sheet metal or fabric, and has perforations 7 located opposite the cells A1, A2; the material forming the outer skin 3 may be a multilayer composite material.
• this panel is intended to be mounted in the inner wall of an aircraft nacelle so that the inner skin 1 is located vis-à-vis the engine which is in this basket.
• the noise emitted by this motor enters the alveoli A1, A2 through the orifices 7 located in the inner skin 1, and vibrates inside these cells which constitute acoustic resonators, thus allowing a dissipation of the energy acoustics and a consequent reduction of the noise level.
• FIG 2 shows a bilayer panel according to the invention comprising two layers of cellular core blocks, respectively formed by blocks B1, B2 and BV 1 B2 ', these layers being assembled between they by known means and sandwiched between an inner skin 1 and an outer skin 3 similar to those of Figure 1.
• the cellular core blocks B1, B2 on the one hand and BV, and B2 'on the other hand cooperate with each other respectively in junction zones 5, 5' whose characteristics will now be explained.
• FIGS. 3 and 4 On which it can be seen that in the cooperation zone 5 of the two blocks B1, B2, the respective cells A1, A2 located on the adjacent edges of these two blocks have been previously opened. , so that they can fit into each other.
• the shear strength of acoustic panels obtained with the method according to the present invention was substantially homogeneous over the entire extent of these panels, including in the junction zones of cellular core blocks.
• Such a homogeneity of resistance is essential because it makes it possible to avoid postponing parasitic forces, especially bending forces, in the outer skin 3.
• One way to achieve this constraint maintenance may be to provide blocks having a surface slightly greater than that of the locations in which they must be positioned and insert them slightly forcibly in these locations.
• Another way of improving the quality of the connection between these blocks may be to provide mechanical means for connecting the cells located on the edges of these blocks, such means possibly comprising for example jumpers or staples.
• this "dry" connection makes it possible to avoid filling the cells A1, A2 located in the junction zone 5 of the blocks B1 and B2 with adhesive: these cells thus remain available to contribute to the attenuation of noise from the side of the outer skin 1 to be placed on the engine side of the aircraft.
• the absence of glue makes it possible to increase the specific acoustic absorption surface of the panel.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Soundproofing, Sound Blocking, And Sound Damping (AREA)
• Laminated Bodies (AREA)
• Exhaust Silencers (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=38765831

Family Applications (1)

Country Status (8)

Families Citing this family (21)

Citations (1)

Family Cites Families (13)

• 2007
  • 2007-02-28 FR FR0701418A patent/FR2913137B1/fr active Active
• 2008
  • 2008-02-06 BR BRPI0807682-0A patent/BRPI0807682A2/pt not_active IP Right Cessation
  • 2008-02-06 CN CN2008800040177A patent/CN101601086B/zh not_active Expired - Fee Related
  • 2008-02-06 WO PCT/FR2008/000141 patent/WO2008113904A2/fr active Application Filing
  • 2008-02-06 CA CA2677558A patent/CA2677558C/fr not_active Expired - Fee Related
  • 2008-02-06 US US12/528,845 patent/US8047326B2/en active Active
  • 2008-02-06 RU RU2009135690/28A patent/RU2450367C2/ru not_active IP Right Cessation
  • 2008-02-06 EP EP08761844A patent/EP2140445A2/de not_active Withdrawn

Patent Citations (1)

Non-Patent Citations (1)

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