FR2546127A1 - Method of protecting a submerged object in order to avoid its identification by sonar - Google Patents
Method of protecting a submerged object in order to avoid its identification by sonar Download PDFInfo
- Publication number
- FR2546127A1 FR2546127A1 FR8308067A FR8308067A FR2546127A1 FR 2546127 A1 FR2546127 A1 FR 2546127A1 FR 8308067 A FR8308067 A FR 8308067A FR 8308067 A FR8308067 A FR 8308067A FR 2546127 A1 FR2546127 A1 FR 2546127A1
- Authority
- FR
- France
- Prior art keywords
- concrete
- layer
- damping
- sonar
- identification
- 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.)
- Pending
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Classifications
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- 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
- B63G7/00—Mine-sweeping; Vessels characterised thereby
- B63G7/02—Mine-sweeping means, Means for destroying mines
- B63G7/08—Mine-sweeping means, Means for destroying mines of acoustic type
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- 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
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F41—WEAPONS
- F41H—ARMOUR; ARMOURED TURRETS; ARMOURED OR ARMED VEHICLES; MEANS OF ATTACK OR DEFENCE, e.g. CAMOUFLAGE, IN GENERAL
- F41H3/00—Camouflage, i.e. means or methods for concealment or disguise
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- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Revetment (AREA)
Abstract
Description
La présente invention concerne un procédé de protection d'un objet immergé de manière å éviter son identification par un sonar, ainsi qu'un objet protégé par ce procédé. The present invention relates to a method of protecting an immersed object so as to avoid its identification by a sonar, as well as an object protected by this method.
La marine utilise couramment des sonars pour détecter à distance des objets immergés mobiles tels que sousmarins ou fixes tels que mines marines. Un sonar utilise, pour réaliser le repérage de ces objets, la réception d'une onde ultrasonore réfléchie par l'objet immergé. The navy commonly uses sonars to remotely detect mobile submerged objects such as submarines or fixed objects such as marine mines. A sonar uses the reception of an ultrasonic wave reflected by the submerged object to locate these objects.
La présente invention a pour but de fournir un procédé permettant à un objet immergé d'éviter de réfléchir une onde ultrasonore venant le frapper et de ne pas pouvoir être ainsi détecté. The object of the present invention is to provide a method allowing an immersed object to avoid reflecting an ultrasonic wave coming to strike it and not to be able to be thus detected.
A cet effet ce procédé de protection d'un objet immergé pour éviter son identification par un sonar est caractérisé en ce que l'on applique sur la surface externe de l'objet une couche de béton léger amortissant les ondes ultrasonores reçues. To this end, this method of protecting an immersed object to avoid its identification by a sonar is characterized in that a layer of light concrete is applied to the external surface of the object which absorbs the ultrasonic waves received.
On sa saint en effet que, lorsqu 'on fait passer des ondes ultrasonores dans le béton, la vitesse de propagation de ces ondes est déterminée par les constantes d'élasticité et de plasticité du matériau, ainsi que par le degré d'hétérogénéité structurelle de celui-ci. Dans le cadre de ces études, on a pu mettre en évidence l'effet d'amortissement ou d'affaiblissement du béton sur les ondes ultrasonores la valeur de cet amortissement étant fonction de la pression initiale des ondes, du trajet parcouru et d'un facteur d'amortissement lié aux caractéristiques du béton. It is indeed holy that, when ultrasonic waves are passed through concrete, the speed of propagation of these waves is determined by the constants of elasticity and plasticity of the material, as well as by the degree of structural heterogeneity of this one. In the context of these studies, we were able to demonstrate the damping or weakening effect of concrete on the ultrasonic waves, the value of this damping being a function of the initial pressure of the waves, the path traveled and a damping factor linked to the characteristics of concrete.
L'amortissement des ondes ultrasonores est dû à deux groupes d'effets physiques: a- un premier groupe produit la transformation directe d'une partie de l'énergie vibratoire mécanique en chaleur. Ce groupe comprend l'hystérésis élastique, la déformation plastique et les processus d'échange de chaleur, dus à l'anisotropie élastique du matériau. L'amortissement ainsi produit est appelé "amortissement par frottement". The damping of ultrasonic waves is due to two groups of physical effects: a- a first group produces the direct transformation of part of the mechanical vibrational energy into heat. This group includes elastic hysteresis, plastic deformation and heat exchange processes, due to the elastic anisotropy of the material. The depreciation thus produced is called "friction damping".
b- un second effet est celui causé par la dispersion des ondes ultrasonores le long des frontières granulaires (grains de granulats, bulles d'eau), donnant lieu à ce que l'on appelle un "amortissement par dispersion.b- a second effect is that caused by the dispersion of the ultrasonic waves along the granular boundaries (granules of aggregates, water bubbles), giving rise to what is called "dispersion damping".
Des mesures comparatives entre jiffêrentes qualités de béton ont montré que les impulsions ultrasonores étaient de plus en plus amorties lorsque la proportion de granulats augmentait et que celle du ciment diminuait. L'amortissement s'est révélé le plus élevé dens du béton léger contenant une quantité relativement faible de ciment (275 kg/m3) et un rapport eau/ciment supérieur à 1 (1,27). Comparative measurements between different qualities of concrete have shown that the ultrasonic pulses are more and more damped when the proportion of aggregates increases and that of the cement decreases. Depreciation was found to be the highest density of lightweight concrete containing a relatively small amount of cement (275 kg / m3) and a water / cement ratio greater than 1 (1.27).
Par conséquent, en appliquant sur la surface externe d'un objet immergé, tel qu'une mine ou un sous-marin, une couche de béton léger, on peut obtenir un amortissement ou affaiblissement suffisant d'une onde ultrasonore reçue, empêchant ainsi toute réémission d'une onde réfléchie et par conséquent l'identification de l'objet. Therefore, by applying a layer of light concrete to the external surface of a submerged object, such as a mine or submarine, sufficient damping or weakening of a received ultrasonic wave can be obtained, thereby preventing any re-emission of a reflected wave and consequently the identification of the object.
La couche de béton formant écran amortisseur d'onde ultrasonore peut être protégée par une feuille de plastomère ou d'élastomère résistant aux agressions chimiques courantes en milieu marin et constituant un bouclier souple contre les chocs. La feuille de plastomère ou d'élastomère peut être coulée directement sur le béton ou fixée par collage, assemblage mécanique ou tout autre moyen approprié. The layer of concrete forming an ultrasonic wave damper screen can be protected by a plastomer or elastomer sheet resistant to common chemical attacks in the marine environment and constituting a flexible shield against shocks. The plastomer or elastomer sheet can be poured directly onto concrete or fixed by gluing, mechanical assembly or any other suitable means.
La composition du béton léger la plus performante pour l'amortissement des ondes ultrasonores est déterminé par l'expérience en faisant varier la dimension et la proportion des granulats, la qualité et la proportion du ciment et le rapport eau/ciment. La densité du béton final utilisé est voisine de 1 et n'est pas supérieure à 1,3. The composition of the best performing lightweight concrete for damping ultrasonic waves is determined by experience by varying the size and proportion of aggregates, the quality and proportion of the cement and the water / cement ratio. The density of the final concrete used is close to 1 and not more than 1.3.
La couche de béton revêtant la paroi protégée peut avoir une épaisseur uniforme, par exemple de l'ordre de 50 mm, ou bien encore elle peut présenter une face extérieure en relief du type "pointes de diamant". Dans ce dernier cas l'élastomère ou le plastomère de protection doivent être coulés, moulés, collés-ou fixés de manière à présenter une surface extérieure plane. The layer of concrete covering the protected wall may have a uniform thickness, for example of the order of 50 mm, or else it may have an external face in relief of the "diamond point" type. In the latter case, the elastomer or the protective plastomer must be cast, molded, glued or fixed so as to have a flat outer surface.
Le procédé suivant l'invention offre l'avantage que l'écran amortisseur constitué par la couche de béton est indéformable sous l'effet de la pression et présente un coefficient d'amortissement régulier quelle que soit la vitesse et quelle que soit la profondeur d'immersion. The method according to the invention offers the advantage that the damping screen formed by the concrete layer is non-deformable under the effect of pressure and has a regular damping coefficient whatever the speed and whatever the depth d 'immersion.
Claims (7)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8308067A FR2546127A1 (en) | 1983-05-16 | 1983-05-16 | Method of protecting a submerged object in order to avoid its identification by sonar |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8308067A FR2546127A1 (en) | 1983-05-16 | 1983-05-16 | Method of protecting a submerged object in order to avoid its identification by sonar |
Publications (1)
Publication Number | Publication Date |
---|---|
FR2546127A1 true FR2546127A1 (en) | 1984-11-23 |
Family
ID=9288881
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
FR8308067A Pending FR2546127A1 (en) | 1983-05-16 | 1983-05-16 | Method of protecting a submerged object in order to avoid its identification by sonar |
Country Status (1)
Country | Link |
---|---|
FR (1) | FR2546127A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1990010927A1 (en) * | 1989-03-16 | 1990-09-20 | Laukien Guenther | Process and device for reducing the noise emission of submerged submarines |
FR2646502A1 (en) * | 1989-04-28 | 1990-11-02 | Lacroix E Tous Artifices | Device for camouflaging a sea mine with respect to mine-seeking sonar |
DE4012094A1 (en) * | 1990-04-14 | 1991-10-17 | Schottel Werft | Underwater sonar detection prevention - involves covering submarine hull with material which absorbs sound waves |
-
1983
- 1983-05-16 FR FR8308067A patent/FR2546127A1/en active Pending
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1990010927A1 (en) * | 1989-03-16 | 1990-09-20 | Laukien Guenther | Process and device for reducing the noise emission of submerged submarines |
US5136547A (en) * | 1989-03-16 | 1992-08-04 | Laukien Guenther | Method and apparatus for reducing for reducing acoustic emission from submerged submarines |
FR2646502A1 (en) * | 1989-04-28 | 1990-11-02 | Lacroix E Tous Artifices | Device for camouflaging a sea mine with respect to mine-seeking sonar |
DE4012094A1 (en) * | 1990-04-14 | 1991-10-17 | Schottel Werft | Underwater sonar detection prevention - involves covering submarine hull with material which absorbs sound waves |
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