EP0292877A1 - Absorbierende Wandverkleidung für akustische Wellen in einem flüssigen Medium - Google Patents

Absorbierende Wandverkleidung für akustische Wellen in einem flüssigen Medium Download PDF

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Publication number
EP0292877A1
EP0292877A1 EP88108044A EP88108044A EP0292877A1 EP 0292877 A1 EP0292877 A1 EP 0292877A1 EP 88108044 A EP88108044 A EP 88108044A EP 88108044 A EP88108044 A EP 88108044A EP 0292877 A1 EP0292877 A1 EP 0292877A1
Authority
EP
European Patent Office
Prior art keywords
conduits
acoustic waves
clearance space
coating
liquid
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
EP88108044A
Other languages
English (en)
French (fr)
Other versions
EP0292877B1 (de
Inventor
René Perret
Etienne Rouget De Gourcez
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.)
Alstom Holdings SA
Vibrachoc SAS
Original Assignee
Vibrachoc SAS
Alstom SA
GEC Alsthom SA
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
Application filed by Vibrachoc SAS, Alstom SA, GEC Alsthom SA filed Critical Vibrachoc SAS
Publication of EP0292877A1 publication Critical patent/EP0292877A1/de
Application granted granted Critical
Publication of EP0292877B1 publication Critical patent/EP0292877B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
    • Y10T428/24149—Honeycomb-like

Definitions

  • the present invention relates to a wall covering absorbing acoustic waves.
  • a noise source and a rigid-walled body are placed in a fluid medium where sound waves can propagate, part of the energy carried by the waves hitting the wall is reflected by it, part is transmitted through the wall, and a small part is absorbed by the material constituting the wall or its coating.
  • the value of the ratio of the energy absorbed to the incident energy, or absorption coefficient depends on the nature of the material constituting or coating the wall, and on the frequency of the sound.
  • the ideal coating would be one that: - would cancel any reflection, even partial, of the incident waves; - would act in a wide frequency band, band which, in the case of water, includes in particular the low frequencies between 10 and 1000 Hertz.
  • Certain known coatings appear to be very insufficient when the ambient medium is constituted by a liquid, especially for low frequencies below 1000 Hz.
  • This coating has a rear face intended to be applied to a rigid base wall and a front face intended to bathe in an ambient medium, in particular a liquid, traversed by acoustic waves. It comprises : - fixed auxiliary walls perpendicular to the base wall and leaving between them elongated energy dissipation conduits in a longitudinal direction also perpendicular to this wall, these conduits being filled with a dissipating material having a kinematic viscosity greater than that of the ambient liquid so that this material dissipates energy by friction when it oscillates longitudinally in these conduits under the action of said acoustic waves, - and a clearance space at the rear of these dissipation conduits to allow this dissipative material to freely carry out such oscillations,
  • said dissipating material is a complex liquid and said clearance space is occupied by flexible enclosures swollen with a gas whose elasticity allows and conditions the oscillations of this liquid.
  • the latter must be separated from the ambient fluid by a membrane which must be both transparent to the acoustic waves to be damped, and sufficiently resistant not to be deteriorated in service. The realization of such a membrane sometimes poses problems.
  • the object of the present invention is to obtain an effective absorption of the acoustic waves in a liquid ambient medium, even at low frequencies, by means of a coating which is more robust and easy to manufacture.
  • this coating which has the above-mentioned common provisions, this coating being characterized by the fact that said dissipative material is a viscoelastic material which responds to a stress by a significant deformation with viscous friction and which responds to the stopping of 'Such a stress by a spontaneous and gradual return to its initial shape, this material adhering to said fixed auxiliary walls so that its elasticity ensures its return in place after a longitudinal displacement.
  • - Said dissipating material contains a mixture of an elastomer and a pulverulent filler, and said clearance space contains a gas.
  • - Said auxiliary walls extend in the thickness of said dissipating material and in that of said clearance space up to said base wall to which they are fixed to thereby ensure the fixing of the entire coating.
  • - Said auxiliary walls form watertight compartments for said gas in said clearance space.
  • - Said gas is enclosed in said clearance space under a pressure which may be greater than atmospheric pressure so as to prevent said dissipative material from being too deformed when the hydrostatic pressure of ambient water increases.
  • the adjacent dissipation conduits may not be completely separated from each other by the auxiliary walls; the important point according to the invention is that there are zones, the conduits, in which the dissipating material can practically deform under the influence of acoustic waves, and rigid elements which, by adhesion, cancel the movement of this material to their contact.
  • the equivalent hydraulic diameter d is equal to the diameter of the conduits if they have a circular section. If their section has a different regular shape, the equivalent hydraulic diameter can be defined as equal to four times the ratio of the area of the straight section of the duct to the wet perimeter.
  • the wet perimeter above is the length, in each cross section, of the line which constitutes the border between the immobilization zone and the zone where a limited displacement of the material is possible, this displacement increasing with the distance from the nearest border line.
  • the frequencies of the waves to be absorbed extend over a wide spectrum and often fall below around 1000 Hz.
  • an absorbent coating is placed against a base wall 1, rigid and immersed in an ambient medium consisting of water 2, comprising, in succession in the medium-wall direction, the following elements: - a metallic honeycomb 5 constituting the dissipation conduits 4; these conduits have a length of the order of 100 mm, a hexagonal section with a section close to 1 cm2 and are full of a viscoelastic material designated by the same reference number 4 and constituted for example by one of the following mixtures Polyisoprenes 100 and 2000 are defined in document FR-A 2 255 313 (GOLE).
  • the expression CBS means cyclohexyl benzothiazole sulfonamide.
  • the honeycomb 5 continues at the rear of this material up to the base wall 1 over a length of for example 60 mm to form compartments 6 which are filled with air at two or three bars and which constitute said clearance space.
  • the metal honeycomb shown in FIG. 2 is replaced by an embossed paper coated with resin delimiting, by gluing, said energy dissipation conduits.
  • the conduits containing the dissipating material are of substantially rectangular section and constituted by the stacking of ribbed plates 14.
  • the ribs 15 of these plates are of a height close to 5 mm and they delimit conduits between them 16.
  • the auxiliary walls have the form of superimposed corrugated sheets such as 20 forming between them conduits such as 22.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Building Environments (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
EP88108044A 1987-05-25 1988-05-19 Absorbierende Wandverkleidung für akustische Wellen in einem flüssigen Medium Expired - Lifetime EP0292877B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8707317 1987-05-25
FR8707317A FR2615994B1 (fr) 1987-05-25 1987-05-25 Revetement de paroi absorbant les ondes acoustiques en milieu liquide

Publications (2)

Publication Number Publication Date
EP0292877A1 true EP0292877A1 (de) 1988-11-30
EP0292877B1 EP0292877B1 (de) 1992-01-22

Family

ID=9351415

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88108044A Expired - Lifetime EP0292877B1 (de) 1987-05-25 1988-05-19 Absorbierende Wandverkleidung für akustische Wellen in einem flüssigen Medium

Country Status (5)

Country Link
US (1) US4817757A (de)
EP (1) EP0292877B1 (de)
CA (1) CA1288055C (de)
DE (1) DE3867908D1 (de)
FR (1) FR2615994B1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2656718A1 (fr) * 1989-12-28 1991-07-05 Thomson Csf Absorbeur acoustique pour milieu fluide, notamment pour milieu marin.
WO1998037541A1 (de) * 1997-02-19 1998-08-27 Rieter Automotive (International) Ag μ/4-ABSORBER MIT EINSTELLBARER BANDBREITE

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5394786A (en) * 1990-06-19 1995-03-07 Suppression Systems Engineering Corp. Acoustic/shock wave attenuating assembly
US5436874A (en) * 1993-11-17 1995-07-25 Martin Marietta Corporation Method and apparatus for sensing acoustic signals in a liquid
FR2767410B1 (fr) * 1997-08-14 1999-10-29 Thomson Marconi Sonar Sas Absorbeur acoustique sous-marin
US20070272482A1 (en) * 2004-04-30 2007-11-29 Kabushiki Kaisha Kobe Seiko Sho Porous Sound Absorbing Structure
US8630435B2 (en) * 2008-08-08 2014-01-14 Nokia Corporation Apparatus incorporating an adsorbent material, and methods of making same
EP2512799A2 (de) * 2009-12-16 2012-10-24 Institut National des Sciences Appliquées de Lyon Mehrlagiger verbundwerkstoff
US11286957B2 (en) * 2018-07-02 2022-03-29 Rohr, Inc. Method for inserting septum into acoustic liner

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2840179A (en) * 1954-06-17 1958-06-24 Miguel C Junger Sound-absorbing panels
FR2255313A1 (de) * 1973-12-20 1975-07-18 Gole Jean
EP0161458A1 (de) * 1984-04-09 1985-11-21 Alsthom Akustische Wellen dämpfende Wandbedeckung
FR2586849A2 (fr) * 1985-05-31 1987-03-06 Vibrasonic Dispositif destine a absorber les ondes sonores.

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2960175A (en) * 1946-06-06 1960-11-15 Edwin M Mcmillan Laminated acoustic window
DE2408028B2 (de) * 1974-02-20 1978-05-11 Fa. Carl Freudenberg, 6940 Weinheim Schallschluckplatte

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2840179A (en) * 1954-06-17 1958-06-24 Miguel C Junger Sound-absorbing panels
FR2255313A1 (de) * 1973-12-20 1975-07-18 Gole Jean
EP0161458A1 (de) * 1984-04-09 1985-11-21 Alsthom Akustische Wellen dämpfende Wandbedeckung
FR2586849A2 (fr) * 1985-05-31 1987-03-06 Vibrasonic Dispositif destine a absorber les ondes sonores.

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2656718A1 (fr) * 1989-12-28 1991-07-05 Thomson Csf Absorbeur acoustique pour milieu fluide, notamment pour milieu marin.
WO1998037541A1 (de) * 1997-02-19 1998-08-27 Rieter Automotive (International) Ag μ/4-ABSORBER MIT EINSTELLBARER BANDBREITE

Also Published As

Publication number Publication date
DE3867908D1 (de) 1992-03-05
CA1288055C (fr) 1991-08-27
FR2615994B1 (fr) 1989-07-28
FR2615994A1 (fr) 1988-12-02
US4817757A (en) 1989-04-04
EP0292877B1 (de) 1992-01-22

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