EP0740287A1 - Matériau absorbant les ondes sonores, notamment en acoustique sous-marine - Google Patents

Matériau absorbant les ondes sonores, notamment en acoustique sous-marine Download PDF

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Publication number
EP0740287A1
EP0740287A1 EP96400782A EP96400782A EP0740287A1 EP 0740287 A1 EP0740287 A1 EP 0740287A1 EP 96400782 A EP96400782 A EP 96400782A EP 96400782 A EP96400782 A EP 96400782A EP 0740287 A1 EP0740287 A1 EP 0740287A1
Authority
EP
European Patent Office
Prior art keywords
panel
rods
metal rods
khz
acoustic waves
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.)
Withdrawn
Application number
EP96400782A
Other languages
German (de)
English (en)
French (fr)
Inventor
Christian Audoly
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.)
Direction General pour lArmement DGA
Etat Francais
Original Assignee
Direction General pour lArmement DGA
Etat Francais
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 Direction General pour lArmement DGA, Etat Francais filed Critical Direction General pour lArmement DGA
Publication of EP0740287A1 publication Critical patent/EP0740287A1/fr
Withdrawn legal-status Critical Current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
    • G10K11/162—Selection of materials
    • G10K11/165—Particles in a matrix

Definitions

  • the invention relates to a material for absorbing sound waves and reducing sound echo when placed on a structure excited by an external sound wave, in particular for underwater applications.
  • An acoustic material is characterized by an input impedance which has for value the product of the density of the material by the speed of the sound.
  • the effectiveness of an acoustic material absorbing sound waves is evaluated by its reflection coefficient, which must be as low as possible and which is defined as the ratio of the reflected pressure to the incident pressure, when a layer of such material is placed on a stationary support.
  • the materials making it possible to strongly attenuate the sound waves must have on the one hand an attenuation of longitudinal celerity ⁇ L high, on the other hand the real part of longitudinal celerity C ' L and a density close to those of the water of sea for underwater applications.
  • Sound wave absorbing coatings consist of an elastomeric matrix in which micro-inclusions of air and possibly mineral fillers are randomly dispersed.
  • the non-attenuated longitudinal waves are converted into attenuated transverse waves which dissipate energy and give the material anechoic properties.
  • Alberich type cellular materials having an elastomer layer in which air cavities are molded.
  • the choice of elastomer and the size of the cavities depends on the frequency band chosen.
  • Patent FR 2656718 describes sound absorbers intended to be immersed in the sea, constituted by honeycomb structures, bearing at one end on a support on which they are fixed and whose other end closed by a membrane is in contact with the incident acoustic wave.
  • the interior of the honeycomb cells is filled with a viscoelastic fluid which absorbs acoustic energy by mechanical dissipation.
  • This absorber is not very sensitive to immersion pressure. but its integration on an underwater vehicle hull is not easy because of the presence of rigid cells filled with fluid.
  • the object of the invention is to propose a device absorbing sound waves in underwater acoustics, not sensitive to immersion pressure and which can be easily integrated on a hull of an underwater vehicle.
  • the subject of the invention is a material absorbing sound waves comprising a viscoelastic matrix in which rods are distributed.
  • the material according to the invention does not contain air and its acoustic properties are independent of the hydrostatic pressure.
  • the stems can be distributed randomly or periodically.
  • the rods are made of metal.
  • the material according to the invention is placed in the form of a panel 1 on a rigid support 2. It makes it possible to reduce the amplitude of the reflected sound wave 4, when the support coated with a material according to the invention is subjected to an incident sound wave 3.
  • FIG. 2 shows the panel 1 produced in a matrix of viscoelastic material 5, in which metal rods 6 are distributed randomly.
  • the rods are preferably placed with their axis parallel to the plane defined by the faces of the panel.
  • a panel according to the invention is produced by pouring a layer of viscoelastic material such as a resin of the polyurethane type Hexcel UR 267 of thickness 40 mm and lateral dimensions 900 mm by 900 mm, on steel rods of length 20 mm and 2 mm in diameter, so that the number of trapped air bubbles is minimized.
  • the volume of the rods represents 7.3% of the total volume of the panel.
  • Such a panel has a reflection coefficient of the order of -15 decibels at atmospheric pressure and of the order of -10 decibels at 40 bars or under an immersion of 400 meters, and this from 20 kHz. These same performances are obtained for frequencies below 20 kHz but with a layer of material thicker than 50 mm.
  • the rods are distributed periodically and form a network.
  • the metal rods can be replaced by mineral or synthetic fibers.
  • a material according to the invention can be placed on surfaces near a sonar antenna to reduce parasitic echoes. In the same way, it protects the sonar antenna from disturbing noise from the carrier ship.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
EP96400782A 1995-04-27 1996-04-11 Matériau absorbant les ondes sonores, notamment en acoustique sous-marine Withdrawn EP0740287A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9505050 1995-04-27
FR9505050A FR2733620B1 (fr) 1995-04-27 1995-04-27 Materiau absorbant les ondes sonores, notamment en acoustique sous-marine

Publications (1)

Publication Number Publication Date
EP0740287A1 true EP0740287A1 (fr) 1996-10-30

Family

ID=9478493

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96400782A Withdrawn EP0740287A1 (fr) 1995-04-27 1996-04-11 Matériau absorbant les ondes sonores, notamment en acoustique sous-marine

Country Status (4)

Country Link
US (1) US5803009A (no)
EP (1) EP0740287A1 (no)
FR (1) FR2733620B1 (no)
NO (1) NO961690L (no)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6530337B1 (en) * 2002-03-18 2003-03-11 The United States Of America As Represented By The Secretary Of The Navy Underwater explosion protection for watercraft
US7819698B2 (en) * 2007-08-22 2010-10-26 Andrew Llc Sealed inner conductor contact for coaxial cable connector

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2881336A (en) * 1956-05-04 1959-04-07 Sperry Prod Inc Damping means for piezo-electric crystals
US3515910A (en) * 1968-11-12 1970-06-02 Us Navy Acoustic absorbing material
FR2234627A1 (no) * 1973-06-21 1975-01-17 Toray Industries
EP0317380A1 (fr) * 1987-10-27 1989-05-24 Thomson-Csf Revêtement anéchoique pour ondes acoustiques
FR2664868A1 (fr) * 1990-07-19 1992-01-24 Bertin & Cie Revetement anechouide, en particulier pour coques de navires et de sous-marins.
EP0530074A1 (en) * 1991-08-28 1993-03-03 Australia Sonar Systems Pty Limited Towed array jacket

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3332754A1 (de) * 1983-09-10 1985-03-28 Fried. Krupp Gmbh, 4300 Essen Unterwasserschiff
FR2656718A1 (fr) * 1989-12-28 1991-07-05 Thomson Csf Absorbeur acoustique pour milieu fluide, notamment pour milieu marin.
US5613460A (en) * 1994-08-31 1997-03-25 Newport News Shipbuilding And Dry Dock Company Submersible vessel external load mounting system

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2881336A (en) * 1956-05-04 1959-04-07 Sperry Prod Inc Damping means for piezo-electric crystals
US3515910A (en) * 1968-11-12 1970-06-02 Us Navy Acoustic absorbing material
FR2234627A1 (no) * 1973-06-21 1975-01-17 Toray Industries
EP0317380A1 (fr) * 1987-10-27 1989-05-24 Thomson-Csf Revêtement anéchoique pour ondes acoustiques
FR2664868A1 (fr) * 1990-07-19 1992-01-24 Bertin & Cie Revetement anechouide, en particulier pour coques de navires et de sous-marins.
EP0530074A1 (en) * 1991-08-28 1993-03-03 Australia Sonar Systems Pty Limited Towed array jacket

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
C.M. SAYERS ET AL.: "Ultrasonic properties of transducer backings", ULTRASONICS, vol. 22, no. 2, March 1984 (1984-03-01), GUILDFORD GB, pages 57 - 60, XP002006377 *

Also Published As

Publication number Publication date
NO961690L (no) 1996-10-28
FR2733620A1 (fr) 1996-10-31
US5803009A (en) 1998-09-08
NO961690D0 (no) 1996-04-26
FR2733620B1 (fr) 1997-06-20

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