WO1992001599A1 - Anechoic coating, particularly for boat or submarine hulls - Google Patents

Anechoic coating, particularly for boat or submarine hulls Download PDF

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Publication number
WO1992001599A1
WO1992001599A1 PCT/FR1991/000561 FR9100561W WO9201599A1 WO 1992001599 A1 WO1992001599 A1 WO 1992001599A1 FR 9100561 W FR9100561 W FR 9100561W WO 9201599 A1 WO9201599 A1 WO 9201599A1
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WO
WIPO (PCT)
Prior art keywords
fluid
tubes
coating according
coating
rods
Prior art date
Application number
PCT/FR1991/000561
Other languages
French (fr)
Inventor
Jean-Claude Guilloud
Daniel Engrand
Original Assignee
Bertin & Cie
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 Bertin & Cie filed Critical Bertin & Cie
Publication of WO1992001599A1 publication Critical patent/WO1992001599A1/en

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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63G—OFFENSIVE OR DEFENSIVE ARRANGEMENTS ON VESSELS; MINE-LAYING; MINE-SWEEPING; SUBMARINES; AIRCRAFT CARRIERS
    • B63G8/00—Underwater vessels, e.g. submarines; Equipment specially adapted therefor
    • B63G8/28—Arrangement of offensive or defensive equipment
    • B63G8/34—Camouflage

Definitions

  • the invention relates to an anecoid coating, capable of absorbing without reflecting the sound waves emitted in the medium in contact with which the coating is located.
  • such a coating can be used on the hulls of surface ships and on those of submarines, to reduce the risks of detection by sonar.
  • Coatings of this type have already been proposed, which essentially consist of sets of small independent juxtaposed parallel tubes, the ends of which are possibly closed by a membrane having an acoustic impedance substantially equal to that of the surrounding fluid medium, such as water for example (see in particular French Patent 2,586,849).
  • an anechoid coating in particular for the hulls of ships and submarines, comprising a plurality of parallel tubes closed at one of their ends by a thickness of material having an acoustic impedance substantially equal to that of the fluid medium in which the said coating is located, the latter being characterized in that the aforementioned tubes are associated with rigid rods forming a piston and penetrating with play in the tubes to constitute with them a plurality of fluid dampers - discs, which are filled with an incompressible fluid and which communicate with each other, the tubes and the pistons being respectively carried by two substantially parallel plates which delimit between them a relatively flat vo ⁇ lume filled with said fluid and closed in a sealed manner, one of the plates being flexible and produced in material having an acoustic impedance substantially equal to that of the medium in which is the dream ⁇ knitted while the other is a rigid plate, so that a local deformation of said flexible plate causes fluid displacement between fluidic dampers in said volume.
  • the coating according to the invention is thus insensitive to external pressure and retains, in the case of a submarine, constant efficiency whatever the depth of immersion. It behaves exactly like full water with respect to sound waves when the direction of propagation of sound waves is not exactly perpendicular to the coating, and has the additional advantage of not having its own frequency and be capable of absorbing and not reflecting sound waves, or more exactly behaving like water, for a wide frequency band.
  • the overall incompressibility of the coating avoids increasing the instability of the hydrostatic balance of the submarine when diving.
  • the aforementioned incompressible fluid has a viscosity much higher than that of the surrounding envi ⁇ fluid medium and a compressibility coefficient substantially equal to that of this fluid medium.
  • the viscosity of this fluid being known, it is possible to choose the transverse clearance of the rods in the tubes and the height of the fluidic dampers to ensure an adaptation of almost perfect acoustic impedance between the coating and the surrounding fluid medium.
  • the coating according to the invention can be in the form of waterproof belt panels, which are fixed by their plates of rigid material externally to the hull of a ship or a submarine or other submerged vehicle ( mines, torpedoes, sonars, etc.), while their plates of flexible material are located on the water side.
  • the coating according to the invention tends to prevent the detection of the ship, the submarine or the device submerged by a sonar.
  • the covering panels according to the invention can be fixed by their flexible plates to the hull of the ship or of the submarine, either on the interior or on the exterior side, in order to absorb the vibrations of the hull.
  • Figure 1 is a partial schematic view in cross section of an anechoid coating according to the invention
  • Figure 2 is a partial schematic view in cross section of a submarine hull fitted with a coating according to the invention.
  • the anechoic coating according to the invention which has been shown diagrammatically in FIG. 1, consists essentially of a plurality of fluid shock absorbers each comprising a small tube 10 into which penetrates with play a rigid rod 12, the fluid damper containing an incompressible fluid 14 which undergoes a shearing force when the rod 12 moves axially in the tube 10.
  • the tubes 10 parallel to each other, are carried by a plate or sheet 16 of flexible material. having an acoustic impedance (product of the density of this material and the speed of sound in this material) which is substantially equal to that of the surrounding fluid medium in which the coating according to the invention is found.
  • the rods 12 are for their part carried by the same rigid plate 18 which is substantially parallel to the flexible plate or sheet 16 and which delimits therewith, in a sealed manner, a relatively flat volume which is filled with the incompressible fluid 14.
  • the surrounding fluid is water and said flexible sheet 16 can be made of an elastomer having an acoustic impedance substantially equal to that some water.
  • the incompressible fluid 14 filling the aforementioned volume is a hyper-viscous liquid whose compressibility coefficient is substantially equal to that of water.
  • a liquid having a viscosity which is about 10,000 times greater than that of water can be used, for example a solution of high molecular weight polymers such as polyacrylamide or cellulose trinitrate.
  • the tubes 10 carried by the flexible sheet or plate 16 terminate at a distance from the rigid plate 18 carrying the rods 12, so that the fluid dampers communicate freely with each other, through the bases of the tubes 10.
  • the coating according to the invention will be in practice in the form of panels 22 which will be fixed, by their rigid plates 18, on the outside face of a shell 24 of ship or submarine. These panels 22 will be contiguous and adjacent so as to cover substantially the entire surface of the shell 24. They will be arranged in a particular way at certain points of the shell to prevent their exterior surface 16 from being exactly perpendicular to an incident sound wave. (case in which the effectiveness of the coating according to the invention decreases a lot).
  • the covering panels according to the invention can be fixed by their flexible sheet 16 to the hull 24 of the ship or submarine, either on the inside or on the outside of this hull, when it is desired to absorb the shell vibrations, which are on the order of a micrometer.
  • all of the tubes 10 may be formed from a honeycomb structure which is anchored by one end to the plate 16 of flexible material.
  • the tubes 10 have a diameter or a transverse dimension of the order of a few millimeters, and a length of a few centimeters.
  • a system of stops between the tubes and the rods which do not impede the free circulation of the fluid, but which limit the maximum relative movement between the tube and the rod (for example lugs provided at the '' inside the tubes and cooperating with pins provided on the rods).

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Mechanical Engineering (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

Anechoic coating, particularly for boat and submarine hulls, comprising a plurality of juxtaposed fluidic dampers which consist of tubes (10) wherein are inserted with some play rigid rods (12) and which are filled with an incompressible fluid (14), the tubes (10) being carried by a plate (16) having an acoustic impedance substantially equal to that of water, whereas the rods (12) are carried by a plate (18) of rigid material. Said coating is substantially incompressible and therefore insensitive to external pressure.

Description

REVETEMENT ANECHOÏDE, EN PARTICULIER POUR COQUES DE NAVIRES OU DE SOUS-MARINS ANECHOID COATING, PARTICULARLY FOR SHIPS OF SHIPS OR SUBMARINES
L'invention concerne un revêtement anéc oïde, capable d'absorber sans les réfléchir les ondes sonores émises dans le milieu au contact duquel se trouve le revêtement.The invention relates to an anecoid coating, capable of absorbing without reflecting the sound waves emitted in the medium in contact with which the coating is located.
En particulier, un tel revêtement peut être utilisé sur les coques de navires de surface et sur celles des sous-marins, pour réduire les risques de détection par sonar.In particular, such a coating can be used on the hulls of surface ships and on those of submarines, to reduce the risks of detection by sonar.
On a déjà proposé des revêtements de ce type, qui sont essentiellement constitués par des ensembles de petits tubes parallèles juxtaposés et indépendants dont les extrémités sont éventuellement fermées par une mem- brane ayant une impédance acoustique sensiblement égale à celle du milieu fluide environnant, tel que l'eau par exemple (voir notamment le Brevet Français 2 586 849) .Coatings of this type have already been proposed, which essentially consist of sets of small independent juxtaposed parallel tubes, the ends of which are possibly closed by a membrane having an acoustic impedance substantially equal to that of the surrounding fluid medium, such as water for example (see in particular French Patent 2,586,849).
L'inconvénient essentiel de ces dispositifs est qu'ils sont compressibles et qu'ils s'écrasent si l'on exerce sur eux une pression. On comprend que, si ces revêtements sont utilisés pour des coques de sous-marins, leur efficacité va diminuer très rapidement avec la pro¬ fondeur d'immersion et devient sensiblement nulle dès une centaine de mètres de profondeur. L'invention a notamment pour but d'éviter cet inconvénient majeur.The essential drawback of these devices is that they are compressible and that they can be crushed if pressure is exerted on them. It is understood that, if these coatings are used for submarine hulls, their efficiency will decrease very quickly with the immersion depth and becomes substantially zero from a hundred meters deep. The object of the invention is in particular to avoid this major drawback.
Elle propose, à cet effet, un revêtement anéchoïde, en particulier pour coques de navires et de sous-marins, comportant une pluralité de tubes parallèles fermés à l'une de leurs extrémités par une épaisseur de matière ayant une impédance acoustique sensiblement égale à celle du milieu fluide dans lequel se trouve ledit revêtement, celui-ci étant caractérisé en ce que les tubes précités sont associés à des tiges rigides formant piston et pénétrant avec jeu dans les tubes pour consti¬ tuer avec ceux-ci une pluralité d'amortisseurs flui- diques, qui sont remplis d'un fluide incompressible et qui communiquent les uns avec les autres, les tubes et les pistons étant respectivement portés par deux plaques sensiblement parallèles qui délimitent entre elles un vo¬ lume relativement plat rempli dudit fluide et fermé de façon étanche, l'une des plaques étant souple et réalisée en matière ayant une impédance acoustique sensiblement égale à celle du milieu dans lequel se trouve le revê¬ tement, tandis que l'autre est une plaque rigide, de sorte qu'une déformation locale de ladite plaque souple entraîne un déplacement de fluide entre amortisseurs fluidiques dans ledit volume.To this end, it proposes an anechoid coating, in particular for the hulls of ships and submarines, comprising a plurality of parallel tubes closed at one of their ends by a thickness of material having an acoustic impedance substantially equal to that of the fluid medium in which the said coating is located, the latter being characterized in that the aforementioned tubes are associated with rigid rods forming a piston and penetrating with play in the tubes to constitute with them a plurality of fluid dampers - discs, which are filled with an incompressible fluid and which communicate with each other, the tubes and the pistons being respectively carried by two substantially parallel plates which delimit between them a relatively flat vo¬ lume filled with said fluid and closed in a sealed manner, one of the plates being flexible and produced in material having an acoustic impedance substantially equal to that of the medium in which is the dream ¬ knitted while the other is a rigid plate, so that a local deformation of said flexible plate causes fluid displacement between fluidic dampers in said volume.
Le revêtement selon l'invention est ainsi insensible à la pression extérieure et conserve, dans le cas d'un sous-marin, une efficacité constante quelle que soit la profondeur d'immersion. Il se comporte exactement comme la pleine eau vis-à-vis des ondes sonores lorsque la direction de propagation des ondes sonores n'est pas exactement perpendiculaire au revêtement, et présente en outre 1'avantage de ne pas avoir de fréquence propre et d'être susceptible d'absorber et de ne pas réfléchir les ondes sonores, ou plus exactement de se comporter comme de l'eau, pour une large bande de fréquences.The coating according to the invention is thus insensitive to external pressure and retains, in the case of a submarine, constant efficiency whatever the depth of immersion. It behaves exactly like full water with respect to sound waves when the direction of propagation of sound waves is not exactly perpendicular to the coating, and has the additional advantage of not having its own frequency and be capable of absorbing and not reflecting sound waves, or more exactly behaving like water, for a wide frequency band.
En outre, et accessoirement, l'incompressibi¬ lité globale du revêtement évite d'accroître l'instabili- té de la balance hydrostatique du sous-marin en plongée.In addition, and incidentally, the overall incompressibility of the coating avoids increasing the instability of the hydrostatic balance of the submarine when diving.
Selon une autre caractéristique de l'invention, le fluide incompressible précité a une viscosité très supérieure à celle du milieu fluide envi¬ ronnant et un coefficient de compressibilité sensiblement égal à celui de ce milieu fluide.According to another characteristic of the invention, the aforementioned incompressible fluid has a viscosity much higher than that of the surrounding envi¬ fluid medium and a compressibility coefficient substantially equal to that of this fluid medium.
La viscosité de ce fluide étant connue, on peut choisir le jeu transversal des tiges dans les tubes et la hauteur des amortisseurs fluidiques pour assurer une adaptation d'impédance acoustique quasi parfaite entre le revêtement et le milieu fluide environnant. Le revêtement selon l'invention peut se pré¬ senter sous forme de panneaux à ceinture etanche, qui sont fixés par leurs plaques de matière rigide extérieu¬ rement sur la coque d'un navire ou d'un sous-marin ou autre engin immergé (mines, torpilles, sonars, etc.), tandis que leurs plaques de matière souple sont situées du côté de l'eau.The viscosity of this fluid being known, it is possible to choose the transverse clearance of the rods in the tubes and the height of the fluidic dampers to ensure an adaptation of almost perfect acoustic impedance between the coating and the surrounding fluid medium. The coating according to the invention can be in the form of waterproof belt panels, which are fixed by their plates of rigid material externally to the hull of a ship or a submarine or other submerged vehicle ( mines, torpedoes, sonars, etc.), while their plates of flexible material are located on the water side.
Dans ces conditions, le revêtement selon l'invention tend à empêcher la détection du navire, du sous-marin ou de l'engin immergé par un sonar.Under these conditions, the coating according to the invention tends to prevent the detection of the ship, the submarine or the device submerged by a sonar.
En variante, les panneaux de revêtement selon l'invention peuvent être fixés par leurs plaques souples sur la coque du navire ou du sous-marin, soit du côté intérieur, soit du côté extérieur, afin d'absorber les vibrations de la coque.As a variant, the covering panels according to the invention can be fixed by their flexible plates to the hull of the ship or of the submarine, either on the interior or on the exterior side, in order to absorb the vibrations of the hull.
L'invention sera mieux comprise et d'autres caractéristiques, détails et avantages de celle-ci appa¬ raîtront plus clairement à la lecture de la description qui suit, faite à titre d'exemple en référence aux des- sins annexés dans lesquels : la figure 1 est une vue schématique partielle en coupe transversale d'un revêtement anéchoïde selon 1'invention; la figure 2 est une vue schématique partielle en coupe transversale d'une coque de sous-marin équipée d'un revêtement selon l'invention.The invention will be better understood and other characteristics, details and advantages thereof will appear more clearly on reading the description which follows, given by way of example with reference to the accompanying drawings in which: Figure 1 is a partial schematic view in cross section of an anechoid coating according to the invention; Figure 2 is a partial schematic view in cross section of a submarine hull fitted with a coating according to the invention.
Le revêtement anéchoïde selon l'invention, qui a été représenté schématiquement en figure 1, est consti¬ tué essentiellement d'une pluralité d'amortisseurs flui- diques comprenant chacun un petit tube 10 dans laquelle pénètre avec jeu une tige rigide 12, l'amortisseur flui- dique contenant un fluide incompressible 14 qui subit un effort de cisaillement lorsque la tige 12 se déplace axialement dans le tube 10. Les tubes 10 parallèles les uns aux autres, sont portés par une plaque ou nappe 16 de matière souple. ayant une impédance acoustique (produit de la masse volu- mique de cette matière et de la vitesse du son dans cette matière) qui est sensiblement égale à celle du milieu fluide environnant dans lequel se trouve le revêtement selon l'invention.The anechoic coating according to the invention, which has been shown diagrammatically in FIG. 1, consists essentially of a plurality of fluid shock absorbers each comprising a small tube 10 into which penetrates with play a rigid rod 12, the fluid damper containing an incompressible fluid 14 which undergoes a shearing force when the rod 12 moves axially in the tube 10. The tubes 10 parallel to each other, are carried by a plate or sheet 16 of flexible material. having an acoustic impedance (product of the density of this material and the speed of sound in this material) which is substantially equal to that of the surrounding fluid medium in which the coating according to the invention is found.
Les tiges 12 sont quant à elles portées par une même plaque rigide 18 qui est sensiblement parallèle à la plaque ou nappe souple 16 et qui délimite avec celle-ci, de façon étanche, un volume relativement plat qui est rempli du fluide incompressible 14.The rods 12 are for their part carried by the same rigid plate 18 which is substantially parallel to the flexible plate or sheet 16 and which delimits therewith, in a sealed manner, a relatively flat volume which is filled with the incompressible fluid 14.
Dans le cas où le revêtement selon 1'invention est destiné à une coque de navire ou de sous-marin, le fluide environnant est de l'eau et ladite nappe souple 16 peut être réalisée en un élastomère ayant une impédance acoustique sensiblement égale à celle de l'eau.In the case where the coating according to the invention is intended for a ship or submarine hull, the surrounding fluid is water and said flexible sheet 16 can be made of an elastomer having an acoustic impedance substantially equal to that some water.
Le fluide incompressible 14 remplissant le volume précité est un liquide hyper-visqueux dont le coefficient de compressibilité est sensiblement égal à celui de l'eau. On peut utiliser un liquide ayant une viscosité qui est 10 000 fois supérieure environ à celle de l'eau, par exemple une solution de polymères à haut poids moléculaire tels que polyacrylamide ou trinitrate de cellulose.The incompressible fluid 14 filling the aforementioned volume is a hyper-viscous liquid whose compressibility coefficient is substantially equal to that of water. A liquid having a viscosity which is about 10,000 times greater than that of water can be used, for example a solution of high molecular weight polymers such as polyacrylamide or cellulose trinitrate.
Les tubes 10 portés par la nappe ou plaque souple 16 se terminent à distance de la plaque rigide 18 portant les tiges 12, de telle sorte que les amortisseurs fluidiques communiquent librement entre eux, par les bases des tubes 10.The tubes 10 carried by the flexible sheet or plate 16 terminate at a distance from the rigid plate 18 carrying the rods 12, so that the fluid dampers communicate freely with each other, through the bases of the tubes 10.
Il s'ensuit que, lorsque la nappe souple 16 est déformée localement, comme indiqué par la ligne en traits pointillés 20, par l'incidence d'une onde sonore, certains tubes 10 se déplacent axiale ent dans un sens et d'autres tubes 10 se déplacent axialement dans le sens opposé par rapport aux tiges 12, ce qui provoque des déplacements locaux du fluide 14 entre les amortisseurs fluidiques. Les déplacements des tubes 10 par rapport aux tiges 12 se traduisent par des efforts de cisaillement du fluide dans les amortisseurs fluidiques. En choisissant correctement le jeu tranversal entre une tige 12 et son tube 10 ainsi que la hauteur des amortisseurs fluidiques, on peut régler, en fonction de la viscosité du fluide 14, l'impédance acoustique du revêtement selon l'invention et l'accorder à peu près exactement sur celle de l'eau environnante. Dans ces conditions, le revêtement selon l'invention se comporte comme la pleine eau vis-à-vis des ondes sonores.It follows that, when the flexible sheet 16 is locally deformed, as indicated by the line in dotted lines 20, by the incidence of a sound wave, certain tubes 10 move axially in one direction and other tubes 10 move axially in the opposite direction relative to the rods 12, which causes local displacements of the fluid 14 between the fluidic dampers. The movements of the tubes 10 relative to the rods 12 result in shearing forces of the fluid in the fluidic dampers. By correctly choosing the transverse clearance between a rod 12 and its tube 10 as well as the height of the fluid shock absorbers, it is possible to adjust, as a function of the viscosity of the fluid 14, the acoustic impedance of the coating according to the invention and to tune it to about exactly that of the surrounding water. Under these conditions, the coating according to the invention behaves like full water with respect to sound waves.
Comme on l'a représenté schématiquement en figure 2, le revêtement selon l'invention va se présenter en pratique sous forme de panneaux 22 qui vont être fixés, par leurs plaques rigides 18, sur la face exté¬ rieure d'une coque 24 de navire ou de sous-marin. Ces panneaux 22 seront contigus et adjacents de façon à recouvrir sensiblement toute la surface de la coque 24. Ils seront agencés de façon particulière en certains points de la coque pour éviter que leur surface exté¬ rieure 16 se trouve exactement perpendiculaire à une onde sonore incidente (cas dans lequel l'efficacité du revête¬ ment selon l'invention diminue beaucoup) . En variante, les panneaux de revêtement selon l'invention peuvent être fixés par leur nappe souple 16 sur la coque 24 du navire ou du sous-marin, soit du côté intérieur, soit du côté extérieur de cette coque, lorsqu'on veut absorber les vibrations de la coque, qui sont de l'ordre du micromètre.As shown schematically in Figure 2, the coating according to the invention will be in practice in the form of panels 22 which will be fixed, by their rigid plates 18, on the outside face of a shell 24 of ship or submarine. These panels 22 will be contiguous and adjacent so as to cover substantially the entire surface of the shell 24. They will be arranged in a particular way at certain points of the shell to prevent their exterior surface 16 from being exactly perpendicular to an incident sound wave. (case in which the effectiveness of the coating according to the invention decreases a lot). As a variant, the covering panels according to the invention can be fixed by their flexible sheet 16 to the hull 24 of the ship or submarine, either on the inside or on the outside of this hull, when it is desired to absorb the shell vibrations, which are on the order of a micrometer.
On peut bien entendu inverser la structure qui a été décrite : il est possible de fixer les tiges rigides 12 sur la nappe 16 de matière souple, tandis que les tubes 10 seront portés par la plaque rigide 18. Avantageusement, l'ensemble des tubes 10 peut être formé d'une structure en nid d'abeille qui est ancrée par une extrémité sur la plaque 16 de matière souple.It is of course possible to reverse the structure which has been described: it is possible to fix the rigid rods 12 on the sheet 16 of flexible material, while the tubes 10 will be carried by the rigid plate 18. Advantageously, all of the tubes 10 may be formed from a honeycomb structure which is anchored by one end to the plate 16 of flexible material.
Typiquement, les tubes 10 ont un diamètre ou une dimension transversale de l'ordre de quelques milli- mètres, et une longueur de quelques centimètres.Typically, the tubes 10 have a diameter or a transverse dimension of the order of a few millimeters, and a length of a few centimeters.
On prévoit également, de préférence, un sys¬ tème de butées entre les tubes et les tiges, qui n'entravent pas la libre circulation du fluide, mais qui limitent le déplacement relatif maximal entre tube et tige (par exemple des ergots prévus à l'intérieur des tubes et coopérant avec des ergots prévus sur les tiges) . There is also preferably provided a system of stops between the tubes and the rods, which do not impede the free circulation of the fluid, but which limit the maximum relative movement between the tube and the rod (for example lugs provided at the '' inside the tubes and cooperating with pins provided on the rods).

Claims

REVENDICATIONS
1. Revêtement anéchoïde, en particulier pour coques de navires et de sous-marins, comprenant une plu- ralité de tubes (10) parallèles fermés à une de leurs extrémités par une épaisseur de matière ayant une impé¬ dance acoustique sensiblement égale à celle du milieu fluide dans lequel se trouve ledit revêtement, caracté¬ risé en ce que les tubes (10) sont associés à des tiges rigides (12) formant pistons et pénétrant avec jeu dans les tubes pour constituer avec ceux-ci une pluralité d'amortisseurs fluidiques qui sont remplis d'un fluide incompressible (14) et qui communiquent les uns avec les autres, les tubes (10) et les tiges (12) étant respecti- vement portés par deux plaques (16, 18) sensiblement parallèles, qui délimitent entre elles un volume relati¬ vement plat rempli dudit fluide (14) et fermé de façon etanche, l'une des plaques étant souple et réalisée en matière ayant une impédance acoustique sensiblement égale à celle du milieu fluide dans lequel se trouve le revête¬ ment, tandis que l'autre plaque est rigide, de telle sorte qu'une déformation locale de ladite plaque souple (16) entraîne un déplacement de fluide entre amortisseurs fluidique dans ledit volume. 1. Anechoid coating, in particular for hulls of ships and submarines, comprising a plurality of parallel tubes (10) closed at one of their ends by a thickness of material having an acoustic impedance substantially equal to that of fluid medium in which said coating is located, caracté¬ ized in that the tubes (10) are associated with rigid rods (12) forming pistons and penetrating with play in the tubes to constitute with them a plurality of fluidic dampers which are filled with an incompressible fluid (14) and which communicate with each other, the tubes (10) and the rods (12) being respectively carried by two substantially parallel plates (16, 18), which delimit between they have a relatively flat volume filled with said fluid (14) and closed in a sealed manner, one of the plates being flexible and made of a material having an acoustic impedance substantially equal to that of the fluid medium in s which is the revête¬ ment, while the other plate is rigid, so that a local deformation of said flexible plate (16) causes a displacement of fluid between fluid shock absorbers in said volume.
2. Revêtement selon la revendication 1, carac¬ térisé en ce que ledit fluide (14) a une viscosité très supérieure à celle du milieu fluide environnant et un coefficient de compressibilité sensiblement égal à celui de ce milieu fluide, tel par exemple que de l'eau. 2. Coating according to claim 1, charac¬ terized in that said fluid (14) has a viscosity much higher than that of the surrounding fluid medium and a compressibility coefficient substantially equal to that of this fluid medium, such as for example that of the 'water.
3. Revêtement selon la revendication 1 ou 2, caractérisé en ce que les dimensions des amortisseurs fluidiques sont déterminées pour assurer, en fonction de la viscosité dudit fluide incompressible (14), une adap¬ tation d'impédance acoustique entre ledit revêtement et le milieu fluide environnant.3. Coating according to claim 1 or 2, characterized in that the dimensions of the fluidic dampers are determined to ensure, as a function of the viscosity of said incompressible fluid (14), an adaptation of acoustic impedance between said coating and the medium surrounding fluid.
4. Revêtement selon l'une des revendications précédentes, caractérisé en ce que les amortisseurs flui- diques sont reliés entre eux par les extrémités ouvertes des tubes (10) .4. Coating according to one of the preceding claims, characterized in that the shock absorbers flui- diques are connected together by the open ends of the tubes (10).
5. Revêtement selon l'une des revendications précédentes, caractérisé en ce que les amortisseurs flui- diques sont sensiblement contigus et adjacents les uns aux autres, et garnissent entièrement ledit volume.5. Coating according to one of the preceding claims, characterized in that the fluid dampers are substantially contiguous and adjacent to each other, and completely fill said volume.
6. Revêtement selon l'une des revendications précédentes, caractérisé par un système de butées entre tubes et tiges, limitant le déplacement maximal relatif des tubes et des tiges.6. Coating according to one of the preceding claims, characterized by a system of stops between tubes and rods, limiting the maximum relative displacement of the tubes and rods.
7. Revêtement selon l'une des revendications précédentes, caractérisé en ce que les tubes (10) sont constitués par une structure en nid d'abeille fixée sur la plaque (16) de matière souple. 7. Coating according to one of the preceding claims, characterized in that the tubes (10) are constituted by a honeycomb structure fixed on the plate (16) of flexible material.
8. Revêtement selon l'une des revendications précédentes, caractérisé en ce qu'il se présente sous forme de panneaux à ceintures étanches fixés par leurs plaques (18) de matière rigide extérieurement sur la coque (24) d'un navire ou d'un sous-marin, tandis que leurs plaques (16) de matière souple sont situées du côté de 1'ea .8. Coating according to one of the preceding claims, characterized in that it is in the form of waterproof belt panels fixed by their plates (18) of rigid material externally on the hull (24) of a ship or a submarine, while their flexible material plates (16) are located on the water side.
9. Revêtement selon l'une des revendications 1 à 7, caractérisé en ce qu'il se présente sous forme de panneaux à ceintures étanches dont les plaques souples (16) sont fixées sur la coque (24) d'un navire ou d'un sous-marin, soit du côté intérieur, soit du côté exté¬ rieur, pour absorber les vibrations de cette coque. 9. Coating according to one of claims 1 to 7, characterized in that it is in the form of watertight belt panels whose flexible plates (16) are fixed to the hull (24) of a ship or a submarine, either on the interior side or on the exterior side, to absorb the vibrations of this hull.
PCT/FR1991/000561 1990-07-19 1991-07-11 Anechoic coating, particularly for boat or submarine hulls WO1992001599A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9009222A FR2664868B1 (en) 1990-07-19 1990-07-19 ANECHOUID COATING, PARTICULARLY FOR SHIPS OF SHIPS AND SUBMARINES.
FR90/09222 1990-07-19

Publications (1)

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WO1992001599A1 true WO1992001599A1 (en) 1992-02-06

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FR (1) FR2664868B1 (en)
WO (1) WO1992001599A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2732806A1 (en) * 1995-04-06 1996-10-11 Mediterranee Const Ind Acoustic insulation enhancement material, esp. for ship's hull
FR3001944A1 (en) * 2013-02-12 2014-08-15 Dcns Element e.g. solid mass, for ship, has external surface that is immersed during use of ship, and hydrodynamic skin that covers wall and is provided on external surface, where hydrodynamic skin is made of polyurethane

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2733620B1 (en) * 1995-04-27 1997-06-20 France Etat SOUND WAVE ABSORBING MATERIAL, ESPECIALLY IN UNDERWATER ACOUSTICS

Citations (4)

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Publication number Priority date Publication date Assignee Title
US3136380A (en) * 1959-10-15 1964-06-09 Riverside Plastics Corp Sonar dome and self-damping component thereof
EP0161458A1 (en) * 1984-04-09 1985-11-21 Alsthom Wall covering absorbing acoustic waves
US4667768A (en) * 1986-05-01 1987-05-26 Lockheed Corporation Sound absorbing panel
EP0317380A1 (en) * 1987-10-27 1989-05-24 Thomson-Csf Lining with low sound reflectivity

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3136380A (en) * 1959-10-15 1964-06-09 Riverside Plastics Corp Sonar dome and self-damping component thereof
EP0161458A1 (en) * 1984-04-09 1985-11-21 Alsthom Wall covering absorbing acoustic waves
US4667768A (en) * 1986-05-01 1987-05-26 Lockheed Corporation Sound absorbing panel
EP0317380A1 (en) * 1987-10-27 1989-05-24 Thomson-Csf Lining with low sound reflectivity

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2732806A1 (en) * 1995-04-06 1996-10-11 Mediterranee Const Ind Acoustic insulation enhancement material, esp. for ship's hull
FR3001944A1 (en) * 2013-02-12 2014-08-15 Dcns Element e.g. solid mass, for ship, has external surface that is immersed during use of ship, and hydrodynamic skin that covers wall and is provided on external surface, where hydrodynamic skin is made of polyurethane

Also Published As

Publication number Publication date
FR2664868A1 (en) 1992-01-24
FR2664868B1 (en) 1992-11-06

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