GB2056367A - Process for producing improved noise attenuation panels - Google Patents

Process for producing improved noise attenuation panels Download PDF

Info

Publication number
GB2056367A
GB2056367A GB8018519A GB8018519A GB2056367A GB 2056367 A GB2056367 A GB 2056367A GB 8018519 A GB8018519 A GB 8018519A GB 8018519 A GB8018519 A GB 8018519A GB 2056367 A GB2056367 A GB 2056367A
Authority
GB
United Kingdom
Prior art keywords
sheet
porous fibrous
fibrous material
adhesive
perforate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8018519A
Other versions
GB2056367B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rohr Inc
Original Assignee
Rohr Industries Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US06/055,681 external-priority patent/US4292356A/en
Priority claimed from US06/064,054 external-priority patent/US4254171A/en
Application filed by Rohr Industries Inc filed Critical Rohr Industries Inc
Publication of GB2056367A publication Critical patent/GB2056367A/en
Application granted granted Critical
Publication of GB2056367B publication Critical patent/GB2056367B/en
Expired legal-status Critical Current

Links

Classifications

    • 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 form; Layered products 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 form; Layered products 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 form; Layered products 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
    • 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 form; Layered products having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • 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 form; Layered products having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/266—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12
    • 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
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • 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
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/82—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to sound only
    • E04B1/84—Sound-absorbing elements
    • E04B1/86—Sound-absorbing elements slab-shaped
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
    • E04C2/30—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure
    • E04C2/34—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts
    • E04C2/36—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts spaced apart by transversely-placed strip material, e.g. honeycomb panels
    • E04C2/365—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts spaced apart by transversely-placed strip material, e.g. honeycomb panels by honeycomb structures
    • 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
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B2038/0052—Other operations not otherwise provided for
    • B32B2038/0076—Curing, vulcanising, cross-linking
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/10—Properties of the layers or laminate having particular acoustical properties
    • 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
    • B32B2607/00—Walls, panels
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B2001/742—Use of special materials; Materials having special structures or shape
    • E04B2001/748—Honeycomb materials

Abstract

Broad band noise attenuation sandwich panels and methods of manufacture utilizing a honeycomb core 11 positioned between and ca bonded to two facing sheets by an adhesive bonding system. One facing sheet 14 is perforated and the other 16 imperforate. A thin sheet 20 of porous fibrous felt or fabric is adhesively bonded to the outer surface of the perforate sheet. The adhesive layer, at least between the perforate sheet and the porous fibrous material, is sufficiently thick to physically isolate the two components and form a funnel shaped opening necked down at the entrance to each perforation. The facing sheets and the core may be of aluminium and are adhesively bonded. <IMAGE>

Description

SPECIFICATION Process for producing improved noise attenuation panels This invention relates to a process for producing improved noise attenuation panels and more particularly to attenuation panels utilized in a severe environment. Examples of its application being within a turbo fan aircraft engine or as outer skin surfaces adjacent to the engine which are exposed to in-flight conditions.
In the design and manufacture of sound attenuation panels which additionally provides structural integrity in severe environments, it has been common practice to provide an attenuation panel wherein honeycomb core material is sandwiched between a perforate and imperforate sheet of material. Panels of this type of construction, although satisfactory for attenuating some specific sound frequencies, are found to be inadequate over a broad range of frequencies customarily encountered within and around the housings of modern turbine engines; it has also been found that the perforations when placed adjacent to high speed gas and air flow areas within or adjacent the engine create turbulence to that high speed flow which reduces the overall efficiency of the engine; it has additionally been found that similar metals or partially non-metals must be utilized in the prior art panels to prevent any galvanic action which occurs between dissimilar metals in direct contact which results in constant bond line delamination between the various adjacent non-similar metal sandwiched components.
There has not been an entirely satisfactory attenuation material with structural integrity and the capability of withstanding severe environmental conditions such as those encountered in and around turbine engines and high-speed gas flow surfaces of aircraft until the emergence of the instant invention.
It is a primary purpose of this invention to provide a manufacturing process and the resulting improved sound attenuation material for reduction of turbine engine noises through a large spectrum of noise frequencies that has the strength required to be utilized in severe aircraft environments as an integral portion of the structure rather than an addition to support structure located where sound attenuation is desired, such as a cowling surrounding an aircraft turbine engine where the attenuation material of the invention is positioned within the engine inlet duct or adjacent the high turbulance region of the fan of a fan jet engine.
A further purpose is to provide an acoustic material incorporating the Helmholtz resonant cavity sound attenuation principles.
A further purpose is to provide suitable isolation or insulation between the components to prevent any galvanic battery like action caused by the direct contact of dissimilar metals.
A further purpose is to provide a method of manufacture that provides a predetermined flow resistance from the outer surface of the attenuation material adjacent to the source of noise to be attenuated in the resonance cavities of the core of the material.
A further purpose of the invention is to provide a process for manufacturing an attenuation material comprising a central honeycomb core having a plurality of cells enclosed on the one surface by an imperforate sheet of material and a perforate sheet of material on the other surface, the outside sound source exposed surface of the perforate material having a layer of fibrous or woven material bonded thereto with improved sound attenuation characteristics.
A still further purpose is to provide an adhesive bond between the perforated sheet and the layer of fibrous or woven material that has the effect of a greater open area than the actual open area through the porous fibrous material and the perforations.
A still further purpose is to provide a sandwiched acoustic material that can be cut to required size, trimmed or drilled without causing physical contact between any adjacent dissimilar metals.
A yet further purpose is to provide a process for bonding together the components of sandwiched acoustic material including honeycomb core sandwiched between an imperforate sheet, and a combined perforate sheet and porous fibrous material wherein the adhesive used for bonding is substantially prevented from flowing by capillary or wicking action into the perforations or between the fibers of the fibrous material.
These and other purposes and advantages of the invention will become better understood by reference to the following detailed description.
When considered with the drawings, in which: Fig. 1 is a perspective view of a completed acoustic panel of the instant invention.
Fig. 2 is a fragmentary vertical section of the acoustic panel of Fig. 1.
Fig. 3 is a showing of a two piece tool used in the manufacturing of the acoustic panel.
Referring now to Figs. 1 and 2 in detail. The processes of manufacturing provide a honeycomb sandwich panel 8. The constituent elements of this honeycomb sandwich panel comprise a single honeycomb core 10, having a plurality of end wise directed cells 12 and outer facing sheets 14 and 1 6. The preferred materials for the core and the facing sheets when utilized in aircraft environment wherein weight is a critical requirement is aluminum due to its weight versus strength and cost characteristics. Other metals or materials could be used where these requirements are not considered. The facing sheet 14 is perforated with a plurality of small perforations 1 8, their size, for example, could range from 0.30 to 0.65 inches.
The perforations 18 provide a range of from 1 5% to 36% open area to the facing sheet 14. The perforations 18 may be punched, drilled, or chem milled through the sheet 14. Chem milling is preferred as the finished cross sectional area can be predetermined and both surfaces of the sheet 14 remain smooth and do not require deburring, grinding, filing, etc., prior to their use. The perforations may be spaced, for example, at 0.081 inch intervals, and for example, in a triangular pattern. Various other intervals and patterns may be used to successfully practice this invention. Sheet 16 is imperforate and forms one closed surface of the cell Helmholtz resonator cavity.
A thin porous fibrous material 20 is adhesively bonded to one surface of the perforate face sheet 14. The adhesive typically used to bond the various panel components is typically a nitrilephenolic or the like structural adhesive. Examples of adhesives found operable are either AF-31 manufactured by the 3-M Company, metal bond 4021 manufactured by Narmco, FM-300 manufactured by Bloomingdale Aerospace Products, or adhesive having the same or similar characteristics as set forth above. These adhesive generally consist of a low solid to solvent solution.
When the solvents are removed from these adhesives by evaporation the viscosity index is elevated.
The preferred porous fibrous material 20 is a stainless steel Dutch twill woven material or the like. Other types of material and weave patterns may also be utilized to successfully practice this invention. In some applications of the attenuation panel a woven material, such as the Dutch twill, may require that the strand crossover points be joined by methods well known in the art such as sintering, diffusion bonding or the like when stainless steel is used.
The adhesive coating for bonding the perforate sheet 14 to the porous fibrous material 20 is preferably applied by spraying on one surface of the perforate sheet a thin layer 22 of the aforementioned type adhesive. The solvent from the adhesive is then removed by evaporation. The surface attraction forces cause the adhesive layer around each perforations 18 of the perforated sheet 14 to take a rounded, funnel like shape, and later during the cure cycle does not soften and flow but merely becomes tacky sufficient to adhere to rather than flow into the porous material while maintaining the funnel like shape.
This inherent behavior of the selected adhesive material effectively enlarges the opening into the perforations 18 at the entrance side of the core cells of the end product, providing enhanced acoustic open area. An example is the use of a perforated sheet 14 having an actual geometric open area of approximately 34%, wherein the final product has an effective open area of approximately 42%, an effective increase of over 10%. This increase in effective open area can only be attributed to the rounded funnel like openings into the perforations created by the layer of adhesive 22 treated in the manner prescribed. The thickness of this layer of adhesive is in the range of 0.001 to 0.004 of an inch.
It has been found that this increased open area effect can be further enhanced by applying a thicker layer of adhesive in the range of .003 to .004 of an inch, removing the .pa solvent, as herein before discussed, and then curing the adhesive layer by prolonged exposure to ambient temperature or by elevating the temperature of the perforated sheet 14 with a thicker layer of adhesive to a normal cure temperature recommended by the manufacturer, generally in the range of 3000F. The thickness of the adhesive layer can be increased by successive thin layers of adhesive with solvent removal and curing between each layer. Effective open areas of approximately 50% have been achieved using a sheet of perforate material having an actual open area of approximately 34%. In the latter buildup/cure method, an additional final layer of adhesive is applied and the solvent is removed.
The perforated layer is now ready as in the first instance to be adhered to the porous fibrous material and then final assembly.
When sizing of the finished panel is required to obtain a specific shape by cutting, trimming, etc., or drilling through hoies is required, the additional thickness of the adhesive buildup maintains continued isolation between the dissimilar metals after the required sizing or drilling.
Another method for providing continuing isolation between dissimilar metals where sizing and/or drilling through the combined perforated sheet 14 and the porous fibrous material 20 is required, is the addition of thin layers of nonmetallic cloth material, for example, materials made from fiberglass, Kevlar or the like, positioned between the perforated sheet and the porous fibrous material in the areas to be sized or drilled.
Non-metallic cloth material of the thickness of approximately .005 of an inch is found to be satisfactory even when used with single thin layers of adhesive. Other thicknesses may be used to practice the invention as necessity requires.
After the perforate sheet and porous fibrous material are bounded together and cured by the desired aforementioned method, the components for the ultimate acoustic panel are then assembled. A layer of 100% epoxy adhesive, such as FM 150 manufactured by Bloomingdale Aerospace Products, or the like, is applied to one surface of the imperforate sheet and the perforation exposed surface of the now combined perforate sheet and porous fibrous material, or to the faying surfaces of the cells of the honeycomb core; the solvent is then removed from the first mentioned adhesive (AF-31 or the like) and the components are then stacked as shown in the various figures, namely, the honeycomb core is sandwiched between the imperforate sheet and the perforation exposed surface of the perforated sheet; pressure generally around 50 psi is then applied from the now outer surface of the imperforate sheet and the porous fibrous material towards the central honeycomb core. This pressure can be applied by any convenient means known in this art, such as, but not limited to a mechanical press or an autoclave; the adhesive on the combined components under pressure is then allowed to cure either by ambient or at an elevated temperature. After curing, the attenuation panel may be sized to a specific shape and/or drilled in the selected areas as desired.
It has been found that even by properly selecting the viscosity index of the adhesives used in the bonding of the various components of acoustical panels, an undesirable amount of the adhesive may wick into the perforations of the facing sheet 1 8 by capillary attraction.
Since the adhesive used in the bonding is cured generally by an elevated temperature in the range of 3000 to 4000 F, expansion of the air or gas trapped within the cells 12 occurs forcing the adhesive from around the perforations 1 8 into the perforations when elevated pressures are reached within the various cells.
Now referring specifically to Figure 3, to prevent any pressure build up within the cells 12, a two-piece tool 22 is utilized in the manufacturing process of the acoustic sandwich material. The tool 22 consists of a perforated plate 24 and a bond tool 26 which has a plurality of juxtaposed grooves 28 extending the length of the bond tool which is at least as long and as wide as the product being assembled. A combination of the perforations 30 of plate 24 and the grooves 28 of the bond tool 26 provide for sufficient venting so that the pressure within the cell is maintained at substantially atmospheric pressure due to the constant venting of the cells through perforations 30 and grooves 28.
The adhesive coated components are then stacked, as above mentioned, with the perforate plate 24 positioned between the groove bond tool 26 and the layer of porous fibrous material 20.
Pressure is then applied to the perforate sheet and the bonding tool along arrows 30, 32 of a sufficient degree to properly hold the components together for the curing of the adhesive. After or during suitable pressure application, the temperature of the components is then elevated to a desired level to timely cure the adhesive. The temperature is then reduced to ambient and either simultaneously or after at least a partial reduction of the elevated temperature, the pressure along arrows 30, 32 is released.
Under the appropriate circumstances, either one or the other of the perforate sheet 24 or the groove bonding tool 26 may not be required in the bonding process to obtain satisfactory results.
Although the foregoing invention has been described in some detail by way of illustration and example, for the purposes of clarity of understanding, it should be understood that certain changes and modifications may be practiced within the spirit of the invention as limited only by the scope of the appended claims.

Claims (14)

1. The honeycomb sandwiched attenuation panel for use adjacent a high velocity gas flow area comprising: honeycomb core having a multiplicity of cells with walls of thin sheet material disposed transversely to the panel; a perforated facing sheet of end sheet material bonded to one core face; an imperforate facing sheet of thin sheet material bonded to the other core face; and a thin sheet of porous fibrous material bonded to the other surface of said perforated facing sheet, wherein the bonding medium insulates that thin sheet of said porous fibrous material from said perforated facing sheet, the pores of said porous fibrous material providing a predetermined impeded communication between the core cells and the atmosphere through the open perforations of said perforated sheet.
2. A honeycomb sandwiched attenuation panel as defined in claim 1, wherein non-metallic cloth is positioned between said perforated sheet and said porous fibrous material at selected iocations.
3. A honeycomb sandwiched attenuation panel as defined in claim 1, wherein the bonding medium positioned between said perforated sheet and said porous fibrous material forms funnel shaped openings leading into the perforations of said perforated sheet.
4. A method of manufacturing honeycomb noise attenuation material having structural integrity positioned adjacent to high speed air and gas flow surfaces of a high speed aircraft, including a central honeycomb core sandwiched between an imperforate sheet and a perforate sheet having a plurality of perforations therethrough, with a layer of porous fibrous material bonded thereto, wherein the combined perforate sheet and layer of porous fibrous material have predetermined open area and resulting flow resistance therethrough, said method comprising the steps of:: (a) cleaning and degreasing the component surfaces to be bonded together; (b) coating one surface of the perforate sheet with a selected first adhesive having a low solid solution; (c) removing the solvent from the first adhesive coating of step (b) to raise the viscosity index of the adhesive; (d) securing together under pressure said perforate sheet with the first adhesive coated surface adjacent the porous fibrous material; (e) curing the substantially solvent-free first adhesive of step (c); (f) applying a layer of a selected second solid 100% epoxy adhesive for bonding together the core and the perforation exposed surface of the combined perforate sheet and porous fibrous material and the imperforate sheet to the other core surface; (g) securing together the imperforate sheet, the central core and the combined perforate sheet and the porous fibrous material; and (h) applying pressure while curing the second adhesive coating on the secured together components of step (g).
5. A method of manufacturing honeycomb attenuation material as defined in claim 4, wherein after step (c) a curing step is included and then steps (b) and (c) are repeated followed by step (d).
6. A method of manufacturing honeycomb attenuation material as defined in claim 4, wherein after step (c), a curing step is included and steps (b), (c) and the curing step again repeated at least once and then steps (b) and (c) are repeated followed by steps (d) through (h).
7. A method as defined in claim 4, wherein prior to step (b), a non-metallic cloth is positioned on said perforated sheet at selected locations and during step (b) said non-metallic cloth is saturated with said first adhesive including its upper and lower surfaces.
8. A method of manufacture as set forth in claim 4, wherein an additional step of venting the cells of said central honeycomb core through said layer of porous fibrous material and said perforated sheet during curing.
9. A method of manufacturing as set forth in claim 8, wherein said venting step comprises the placing of a corrugated tool adjacent to the porous fibrous material side of said combined sheet material prior to step (h).
10. A method of manufacture as set forth in claim 8, wherein said venting step comprises the placing of a second perforated sheet of material adjacent to the porous fibrous surface of said combined sheet of perforated and porous fibrous material prior to step (h).
11. A method of manufacturing as set forth in claim 8, including-the steps of placing a second perforated sheet of material adjacent to the porous fibrous surface of said combined sheet of perforate and porous fibrous material and placing a corrugated tool adjacent to said second perforated sheet of material prior to step (h).
12. A tool for holding together in proper positional relationship a central cellular core sandwiched positioned between an imperforate and a first perforate sheet, said first perforate sheet having an outer exposed layer of porous fibrous material are bonded thereto, while being bonded together by a coating of adhesive between said central cellular core and said imperforate and perforate sheets comprising: a bond tool at least as large as the sandwiched components, said bond tool having a corrugated surface, the corrugations extending along the entire length of one dimension of said bond tool for allowing the cells of said central cellular core to be vented to the atmosphere through the first perforate sheet and porous fibrous material combination while said adhesive coatings cure.
13. A tool as defined in claim 12, wherein said tool additionally comprises a second perforate sheet positioned between said porous fibrous material and said bond tool.
14. A method of manufacturing a honeycomb attenuation material substantially as hereinbefore described.
1 5. A honeycomb sandwich attenuation panel substantially as described with reference to the accompanying drawings.
GB8018519A 1979-07-06 1980-06-05 Process for producing noise attenuation panels Expired GB2056367B (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US06/055,681 US4292356A (en) 1979-07-06 1979-07-06 Method of manufacturing of honeycomb noise attenuation structure and the structure resulting from the method
US6400079A 1979-08-06 1979-08-06
US06/064,054 US4254171A (en) 1975-08-13 1979-08-06 Method of manufacture of honeycomb noise attenuation structure and the resulting structure produced thereby

Publications (2)

Publication Number Publication Date
GB2056367A true GB2056367A (en) 1981-03-18
GB2056367B GB2056367B (en) 1983-06-02

Family

ID=27368891

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8018519A Expired GB2056367B (en) 1979-07-06 1980-06-05 Process for producing noise attenuation panels

Country Status (3)

Country Link
DE (1) DE3025617A1 (en)
FR (1) FR2460779A1 (en)
GB (1) GB2056367B (en)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3318334A1 (en) * 1982-05-19 1983-11-24 Short Brothers Ltd., Belfast SOUND-ABSORBENT PLATE AND METHOD FOR THEIR PRODUCTION
EP0139765A1 (en) * 1983-03-30 1985-05-08 Shin Nippon Core Co. Ltd. Sound-adjusting plate
EP0155034A2 (en) * 1984-02-29 1985-09-18 Fokker Aircraft B.V. Sound attenuating structure
WO1992000183A1 (en) * 1990-06-28 1992-01-09 Short Brothers Plc A composite structural component
EP0747547A1 (en) * 1995-06-08 1996-12-11 AEROSPATIALE SOCIETE NATIONALE INDUSTRIELLE, Société Anonyme Method of fabrication of a plate or the like with structural and acoustic features and plate obtained this way
EP0790361A1 (en) * 1996-02-19 1997-08-20 Giat Industries Lightweight transportable technical shelter
US6187123B1 (en) 1995-03-29 2001-02-13 Aerospatiale Societe Nationale Industrielle Method for producing a lightened SiC sandwich type structure with a honeycomb-shaped core and structure obtained by said method
US6267838B1 (en) 1995-06-09 2001-07-31 Aerospatiale Societe Nationale Industrielle Sandwich panel made of a composite material and production method
NL1030971C2 (en) * 2006-01-20 2007-07-23 Coatacoustic B V Acoustic panel containing holes, used for soundproofing walls or ceilings, has holes blocked by covering at one end and nonwoven at other end
US8820477B1 (en) 2013-07-29 2014-09-02 The Boeing Company Acoustic panel
US9643392B2 (en) 2013-07-29 2017-05-09 The Boeing Company Septumization of honeycomb sandwiches
US9693166B2 (en) 2014-06-24 2017-06-27 The Boeing Company Automated production of acoustic structures
US9931825B2 (en) 2014-07-09 2018-04-03 The Boeing Company Septumization of cellular cores
US10279548B2 (en) 2014-11-03 2019-05-07 Short Brothers Plc Methods and precursors for manufacturing a perforated composite part
CN112687254A (en) * 2020-12-18 2021-04-20 哈尔滨工程大学 Micro-perforated corrugated-honeycomb metamaterial plate structure capable of improving sound insulation and absorption performance

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2061819B (en) * 1979-10-29 1983-03-09 Rohr Industries Inc Honeycomb noise attenuation structure
DE19653850C2 (en) * 1996-12-21 1999-01-28 Daimler Benz Aerospace Airbus Wall element
DE19804718C2 (en) 1998-02-06 2001-09-13 Eurocopter Deutschland Sound absorbing sandwich wall
DE102004062103A1 (en) * 2004-12-23 2006-07-13 Pelzer Acoustic Products Gmbh Porous, lateral sound absorber with local air gap

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3166149A (en) * 1965-01-19 Damped-resonator acoustical panels
US3770560A (en) * 1971-10-21 1973-11-06 American Cyanamid Co Composite laminate with a thin, perforated outer layer and cavitated bonded backing member
AU478351B2 (en) * 1973-04-13 1975-10-09 Comalco Cj. &S. )Pty. Limited Mesh reinforced elastomeric polymers
US3910374A (en) * 1974-03-18 1975-10-07 Rohr Industries Inc Low frequency structural acoustic attenuator
FR2396868A1 (en) * 1977-07-07 1979-02-02 Snecma Combined thermal and noise insulation for jet pipes - has metallic honeycomb covered with layer of porous refractory material in metal casing
US4155211A (en) * 1977-12-23 1979-05-22 Haworth Mfg., Inc. Sound absorbing panel
GB2059341B (en) * 1979-09-17 1983-06-08 Rohr Industries Inc Double layer attenuation panel

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3318334A1 (en) * 1982-05-19 1983-11-24 Short Brothers Ltd., Belfast SOUND-ABSORBENT PLATE AND METHOD FOR THEIR PRODUCTION
FR2527367A1 (en) * 1982-05-19 1983-11-25 Short Brothers Ltd DEVICE FOR ATTENUATING SOUND ENERGY AND MANUFACTURING METHOD THEREOF
EP0139765A1 (en) * 1983-03-30 1985-05-08 Shin Nippon Core Co. Ltd. Sound-adjusting plate
EP0139765A4 (en) * 1983-03-30 1985-10-14 Shin Nippon Core Co Ltd Sound-adjusting plate.
EP0155034A2 (en) * 1984-02-29 1985-09-18 Fokker Aircraft B.V. Sound attenuating structure
EP0155034A3 (en) * 1984-02-29 1987-04-15 Fokker B.V. Sound attentuating structure
WO1992000183A1 (en) * 1990-06-28 1992-01-09 Short Brothers Plc A composite structural component
US6187123B1 (en) 1995-03-29 2001-02-13 Aerospatiale Societe Nationale Industrielle Method for producing a lightened SiC sandwich type structure with a honeycomb-shaped core and structure obtained by said method
FR2735166A1 (en) * 1995-06-08 1996-12-13 Aerospatiale METHOD OF MANUFACTURING A PANEL OR THE LIKE WITH STRUCTURAL AND ACOUSTIC PROPERTIES AND THE PANEL THUS OBTAINED
US5888610A (en) * 1995-06-08 1999-03-30 Aerospatiale Societe Nationale Industrielle Method for producing a panel or the like with structural and acoustic properties and panel obtained by said method
EP0747547A1 (en) * 1995-06-08 1996-12-11 AEROSPATIALE SOCIETE NATIONALE INDUSTRIELLE, Société Anonyme Method of fabrication of a plate or the like with structural and acoustic features and plate obtained this way
US6267838B1 (en) 1995-06-09 2001-07-31 Aerospatiale Societe Nationale Industrielle Sandwich panel made of a composite material and production method
EP0790361A1 (en) * 1996-02-19 1997-08-20 Giat Industries Lightweight transportable technical shelter
FR2745024A1 (en) * 1996-02-19 1997-08-22 Giat Ind Sa TECHNICAL SHELTER MOBILE ALLEGE
NL1030971C2 (en) * 2006-01-20 2007-07-23 Coatacoustic B V Acoustic panel containing holes, used for soundproofing walls or ceilings, has holes blocked by covering at one end and nonwoven at other end
US9643392B2 (en) 2013-07-29 2017-05-09 The Boeing Company Septumization of honeycomb sandwiches
US8820477B1 (en) 2013-07-29 2014-09-02 The Boeing Company Acoustic panel
US10363726B2 (en) 2013-07-29 2019-07-30 The Boeing Company Septumization of honeycomb sandwiches
US9693166B2 (en) 2014-06-24 2017-06-27 The Boeing Company Automated production of acoustic structures
US10542363B2 (en) 2014-06-24 2020-01-21 The Boeing Company Automated production of acoustic structures
US9931825B2 (en) 2014-07-09 2018-04-03 The Boeing Company Septumization of cellular cores
US10828882B2 (en) 2014-07-09 2020-11-10 The Boeing Company Septumization of cellular cores
US10279548B2 (en) 2014-11-03 2019-05-07 Short Brothers Plc Methods and precursors for manufacturing a perforated composite part
US10946596B2 (en) 2014-11-03 2021-03-16 Short Brothers Plc Methods and precursors for manufacturing a perforated composite part
CN112687254A (en) * 2020-12-18 2021-04-20 哈尔滨工程大学 Micro-perforated corrugated-honeycomb metamaterial plate structure capable of improving sound insulation and absorption performance
CN112687254B (en) * 2020-12-18 2023-02-03 哈尔滨工程大学 Micro-perforated corrugated-honeycomb metamaterial plate structure capable of improving sound insulation and absorption performance

Also Published As

Publication number Publication date
DE3025617A1 (en) 1981-02-12
FR2460779B1 (en) 1984-12-28
DE3025617C2 (en) 1987-04-30
GB2056367B (en) 1983-06-02
FR2460779A1 (en) 1981-01-30

Similar Documents

Publication Publication Date Title
US4539244A (en) Honeycomb noise attenuation structure
US4254171A (en) Method of manufacture of honeycomb noise attenuation structure and the resulting structure produced thereby
US4300978A (en) Bonding tool for venting honeycomb noise attenuation structure during manufacture
US4294329A (en) Double layer attenuation panel with two layers of linear type material
US4318453A (en) Double layer attenuation panel
GB2056367A (en) Process for producing improved noise attenuation panels
US4465725A (en) Noise suppression panel
EP2472509B1 (en) Septum cap for acoustic honeycomb
US10363726B2 (en) Septumization of honeycomb sandwiches
US4433021A (en) Sound attenuation sandwich panel including barrier material for corrosion control
US4541879A (en) Method of manufacture of noise suppression panel
US4291079A (en) Method of manufacturing a honeycomb noise attenuation structure and the structure resulting therefrom
US4001473A (en) Sound attenuating structural honeycomb sandwich material
EP1866489B1 (en) Acoustic septum cap honeycomb
US8607924B2 (en) Anchoring of septums in acoustic honeycomb
US5807628A (en) Method of repairing sound attenuation structure used for aircraft applications
US4292356A (en) Method of manufacturing of honeycomb noise attenuation structure and the structure resulting from the method
EP3132930A1 (en) Acoustic sandwich panel and method
US4990391A (en) Reticulated core to perforate sheet bonding and galvanic barrier
US4269882A (en) Method of manufacturing of honeycomb noise attenuation structure and the structure resulting therefrom
EP3276614B1 (en) Method for making contoured acoustic structures
EP3524423B1 (en) Thermoplastic bonding process for acoustically treated linear facesheets
GB2122540A (en) Means for attenuating sound energy, and method of manufacture thereof
US11674475B2 (en) Structural single degree of freedom acoustic liner
CN113002074A (en) Structural single degree of freedom panel acoustic pad

Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19960605