EP0221794A1 - Malleable modular car armour - Google Patents

Abstract

Device for protecting a structure against the impact of projectiles and fragments or explosion fragments, said device being of the type having a laminated structure based on elastomer and fibers, preferably constituted by organic fibers of aromatic polyamide . The device according to the invention is characterized in that said laminated structure comprises at least one flexible module consisting of a plurality of superimposed composite layers, each composite layer comprising a textile intermediate layer made of said fibers and adhered on either side to a very thin film made of said elastomer, the different composite layers being joined together by vulcanization and their number being a function of the degree of flexibility desired for the module, and in that said module is suitable for application preferably by bonding, but also by screwing or riveting or other suitable means, to any support, metallic or not, curved or not, in particular constituted by said structure to be protected or by another protection device of a type known per se already optionally fitted to this structure or yet another module of the same type. Application to the shielding of structures, in particular constituted by motor vehicles.

Description

The present invention relates to a protection device resistant to the impact of projectiles and fragments or fragments of explosions, which is intended more particularly for the protection of motor vehicles.

Several solutions have already been proposed for producing shielding devices which, in almost all cases, have a laminated composite structure comprising at least one layer of inorganic (or natural) fibers, such as glass fibers, or organic fibers ( or synthetic), such as polyamide ("NYLON") and especially aromatic polyamide ("KEVLAR") fibers, the latter being now practically universally used in the manufacture of ballistic protective devices, and this because of the resistance specific mechanics, namely per unit mass, high of the "KEVLAR" (which is known to be a trademark registered by DUPONT DE NEMOURS) which is five times greater than the specific resistance of steel and twice the specific resistance "NYLON", "KEVLAR" also having the property of absorbing large amounts of kinetic energy.

By way of examples of the solutions already proposed, mention may be made of a number of patents, the subject of which is briefly recalled below.

The VALLCORBA TURA patent, FR. 2,348,991, relates to a textile sheet for the production of impact and explosion-resistant clothing, which consists of an aramid (or aromatic polyamide) filament, in particular KEVLAR, from 500 to 2,500 denier, and in particular from 1,000 deniers, woven in simple plain weave and mass-colored, said filament being thermally fixed by coating at least one face with impermeable resin by passing through a gelling tunnel, from which it leaves ready for making bullet-proof vests, for example.

For the bulletproof vest to be effective, the fabric is folded back on itself, which gives structure laminate that can have a maximum number of 30 to 40 plies, ensuring protection against the impact of any type of weapon and projectile in the event of war and combat, explosions (dynamite), sport hunting.

You can also make explosion-proof blankets.

Between the successive layers of aramid fibers, it is possible to have free fibers of aramid or of another type of refractory fibers such as "'FIBERFRAX", "KAOXOOL" "TRITON", "CERAFIBER" "," REFRASIL " , etc ...., the inclusion of these free fibers is not however essential.

The BOTTINI et al patent, FR. 2 402 855, relates to a composite bullet-resistant material, which can be in the form of flat or curved sheets, as well as in hollow bodies of complex shape. It is composed of a plurality of fabrics made of aromatic polyamide fibers ("ballistic NYLON"), at least some of which are of the ordinary "linen" type and others of the "batavia" type, each being impregnated with polyester resins. unsaturated, which tissues are superimposed on each other one by one or in a group, the mutual association being obtained at high pressure in the desired shape. In the case where only the two fabrics of the aforementioned type are used, the fabrics of the "batavia" group are superimposed parallel or perpendicular to the adjacent "cloth" fabrics.

This Patent corresponds to the American patent JS 4,200,677.

The Patent of the FRANCO-GERMAN INSTITUTE OF RESEARCH OF SAINT-LOUIS, ^FR 2 425 046, relates to a projectile-proof armor consisting of a first plate exposed to the impact of projectiles and made of hard material, such as steel, the thickness of which is greater than or equal to 0.3 times the caliber of the projectiles against which the armor device is provided, and by a second plate made of low-density laminate material delamination energy, the thickness of which is at least twice the caliber of projectiles, and composed of inorganic fibers, such as glass fibers, or organic fibers, such as aromatic polyamide (or aramid) fibers, which fibers are bonded by a soft resin, i.e. made with a low dose of hardener, such as a polyester resin, or bonded using a natural or synthetic elastomer.

The assembly between the two plates is done by gluing or using continuous or discontinuous mechanical means.

Patent IMI KYNOCH LTD, FR 2 443 397, relates to a container for the storage of dangerous materials, for example explosives, the wall of which has a laminated structure comprising at least one relatively rigid layer, made of plastic, in particular thermosetting, reinforced with fibers, in particular glass or polyamide, and at least one layer of elastomer, in particular of chlorosulfonated polyethylene, the rigid layer being closer to the interior of the container than the layer of elastomer.

In the case where the container wall has several rigid and elastomeric layers, these are arranged alternately.

The laminate structure may also include a metallic outer layer.

The Patent of the SOCIETE NATIONALE DES POUDRES ET EXPLOSIFS, _FR 2 469 277, relates to a device for protection against shocks, in particular due to the impact of a bullet or fragments projected by an explosion, or also due to collisions between two body, for example two cars.

This device is of the type comprising a laminated structure consisting of superimposed layers of fabrics based on inorganic fibers, such as glass fibers, or organic fibers, such as aromatic polyamide fibers or aramid ("KEVLAR") and an impregnation resin, in particular polyester or polyepoxide, This Patent claims the use, in a protection device of the above type, of a viscoelastic thermosetting or thermoplastic resin having a loss factor included between 0.5 and 1.5, a modulus of elasticity E between 10 ⁶ and 10 ⁹ _{N / m} ² , at a frequency of 100 Hz and at the temperature of use.

• - 10% et 30%, et de préférence entre 15% et 24%, dans le cas de réalisation de blindages légers, ou
• - 40% et 80%, dans le cas de réalisation de pare-chocs d'automobiles.

The weight ratio of viscoelastic resin, relative to the total weight of the protective device, is between:

• - 10% and 30%, and preferably between 15% and 24%, in the case of making light armorings, or
• - 40% and 80%, in the case of automobile bumpers.

The APPRICH patent, _FR 2 506 447, relates to armouring for wall elements, in particular metal parts of the underside of motor vehicles, against the action of explosive devices, comprising at least one layer of a coherent and impregnated fiber mat resin.

The fibers can be entirely aramid fibers (aromatic polyamides) and in particular fibers of "KEVLAR. ¹

In the case where said mat is made only partially from aramid fibers, it may also include cotton fibers, or polyamide fibers.

In each case, the mat can be formed by a fabric with several layers of warp and weft threads, connected to each other.

The impregnating resin is a resin with one or more components, in particular a polyurethane, polyethylene or polyvinyl chloride resin.

The AEROJET patent, FR 1 605 066, relates to an impact-resistant material, whose penetration resistance / weight ratio is exceptionally high and which can be used to make breastplates for men or shields for air transport equipment, personnel transport vehicles, etc.

The proposed material comprises several bonded layers of a fabric constituted by an interlacing of glass fibers, in particular in the form of wicks, and of "NYLON", impregnated with resin, in particular polyester, epoxy or rubber-phenolic.

The relative proportions by weight of glass fibers and "NYLON" are between 90 parts of glass and 10 parts of "NYLON", and 10 parts of glass and 90 parts of "NYLON".

The results of the impact resistance tests of this combination of fibers are superior to the results obtained with one or the other type of fibers used separately.

The aforementioned impact-resistant material can also comprise an external surface layer of glass, alumina, boron carbide, silicon carbide, etc.

• - une plaque en matière dure brisant le projectile, dirigée du côté du tir,
• - une matière d'appui freinant le projectile, disposée sur la face arrière de cette plaque, et
• - une couche de grand allongement de rupture, disposée sur la face avant de ladite plaque.

The MAN MASCHINENFABRIK patent, FR 2 522 404, relates to a plate-shaped shielding element, of the type consisting of:

• - a plate of hard material breaking the projectile, directed towards the side of the shot,
• a bearing material braking the projectile, disposed on the rear face of this plate, and
• - A layer of great elongation at break, disposed on the front face of said plate.

According to this patent, the layer of great elongation at break is made of polyurethane, the plate of hard material is of sintered ceramic with aluminum oxide or of boron carbide, and the support material is a fabric of textile fibers. , in particular of aromatic polyamide fibers, consisting of several layers superposed loosely and only weakly bonded together.

The support material can be coated on one side with said hard and moisture-protected material, on the area not covered with this hard material, by curable synthetic impregnating resins.

The American patent MEDLIN, US 4 352 316, relates to armored vehicles with light armor, having the appearance of normal vehicles, and more particularly a light protection plate capable of dissipating at least part of the kinetic energy of high-projectiles. speed.

• - une pluralité de feuilles balistiques (à savoir, résistant à la pénétration de la part de projectiles à haute vitesse) consistant en fibres balistiques,
• - un matériau d'apprêt, et
• - un matériau de liaison qui se lie de manière imparfaite à ce matériau d'apprêt.

This bulletproof plate includes:

• - a plurality of ballistic sheets (i.e., resistant to penetration by high speed projectiles) consisting of ballistic fibers,
• - a finishing material, and
• - a bonding material which binds imperfectly to this finishing material.

The finishing material is applied to said plurality of sheets, and the sheets thus prepared are laminated together using the binder, so as to delaminate under the action of the impact of bullets at high speed.

The plate proposed by the MEDLIN patent, US4 352 316, is in accordance with the results of tests according to which the most effective means for absorbing the kinetic energy of a projectile is to deform, separate (or delaminate) and penetrate a certain number. separate armor sheets.

Worthy of note is also the European patent CAPPA, EP 49 014, although this is outside the scope of the present invention because, unlike the known technique, impact resistance is improved by giving the laminate a non-woven structure. -delaminable, namely a structure which interconnects the different layers of a laminate so as to give the assembly the capacity to elastically absorb the impact due to the projectile without delaminating.

• - une matrice à nid d'abeille, qui est obtenue par chauffage et compression de ladite résine thermoplastique et qui constitue un support tridimensionnel,
• - des couches de matière textile, constituées par des fibres synthétiques nobles, telles que des fibres de carbone, d'aramide, de bore ou analogues, qui présentent des propriétés mécaniques exceptionnellement élevées et qui sont entrelacées et contenues librement dans les cavités de ladite structure à nid d'abeille et encapsulées par ces cavités, à savoir que les fibres sont libres de glisser le long de la cavité correspondante.

It is an improved non-metallic screen which is highly resistant to the impacts of projectiles and of the type constituted by the alternating superposition of layers of thermoplastic resin and textile material, which bulletproof protective screen comprises:

• - a honeycomb matrix, which is obtained by heating and compression of said thermoplastic resin and which constitutes a three-dimensional support,
• - layers of textile material, constituted by noble synthetic fibers, such as carbon, aramid, boron fibers or the like, which have exceptionally high mechanical properties and which are intertwined and contained freely in the cavities of said structure honeycomb and encapsulated by these cavities, namely that the fibers are free to slide along the corresponding cavity.

• - d'une part, que pour réaliser des structures flexibles, notamment adaptées à la confection de gilets anti-balles, on se limite à l'emploi de feuilles textiles repliées sur elles-mêmes (cf. le Brevet VALLCORBA TURA), toutefois cette solution ne convient pas pour la réalisation de blindages de véhicules automobiles notamment, et
• - d'autre part, que l'adaptation de feuilles textiles à la réalisation de dispositifs de blindage demande la coopération avec des plaques ou couches d'une certaine rigidité, les feuilles textiles étant quasi généralement imprégnées à l'aide d'un agent de liaison résineux ou élastomère (seulement le Brevet IMI/KYNOCH LTD décrit un dispositif de protection dont la structure stratifiée comporte au moins une couche réalisée complètement en élastomère, mais également celle-ci coopère avec au moins une couche rigide).

The non-delaminable structure is obtained by applying rules, most of which are contrary to usual practice and in particular by achieving an adhesion, or bond, between the matrix and the fibers negligible or zero, which is obtained by choosing unbleached materials. suitable for the matrix and the fibers, or by treating these fibers with an agent which makes them impermeable to the matrix. The above shows:

• - on the one hand, that to achieve flexible structures, particularly suitable for making bulletproof vests, we limit ourselves to the use of textile sheets folded back on themselves (cf. the VALLCORBA TURA patent), however this solution is not suitable for making armor plating for motor vehicles in particular, and
• - on the other hand, that the adaptation of textile sheets to the production of shielding devices requires cooperation with plates or layers of a certain rigidity, the textile sheets being almost generally impregnated using a resinous or elastomeric bond (only the IMI / KYNOCH LTD Patent describes a protection device whose laminated structure comprises at least one layer made completely elastomer, but also it cooperates with at least one rigid layer).

In addition, the adaptation to particular, generally curved, shapes of objects to be protected is subject to the application of high-pressure forming processes (see the BOTTINI patent) or, in some cases, hot forming ( this is the case of devices using laminated panels made of reinforced plastic or appropriately reinforced).

• - en ce qui concerne la conformation à des supports galbés, celle-ci est possible seulement à condition de disposer préalablement d'un moule spécial, généralement coûteux, et dont l'emploi est justifié essentiellement dans le cas de production de grandes séries,
• - en ce qui concerne la découpe des pièces, celle-ci est difficile, ce qui nécessite de faire appel à des outils également spéciaux, tels que des scies à dents diamantées, des dispositifs à jets d'eau à haute pression ou des dispositifs laser,
• - en ce qui concerne les dimensions des pièces, celles-ci sont disponibles dans une gamme relativement limitée, surtout à cause de problèmesde découpage,
• - en ce qui concerne les conditions d'hygiène et de sécurité de travail, celles-ci imposent le respect de normes rigoureusement strictes en raison de la présence de résines volatiles, et
• - en ce qui concerne la fabrication des pièces, celles-ci s'effectue sur des presses ou dans des autoclaves, ce qui entraîne un nombre important d'opérations manuelles, notamment dues à la superposition des couches de ces pièces à structure stratifiée., et donc des temps d'immobilisation des machines également importants qui élèvent le coût énergétique.

Summarizing the above, it can therefore be concluded that the currently available shielding devices are of the rigid or semi-rigid type which, while offering effective protection, have a certain number of drawbacks, both in terms of their manufacture and of their use, which limit their applications, in particular:

• - as regards the conformation to curved supports, this is only possible provided that a special mold, generally expensive, is available beforehand, the use of which is justified essentially in the case of mass production,
• - as far as cutting the parts is concerned, this is difficult, which requires the use of equally special tools, such as diamond tooth saws, high pressure water jet devices or laser devices ,
• - with regard to the dimensions of the parts, these are available in a relatively limited range, above all because of cutting problems,
• - with regard to the conditions of hygiene and safety at work, these require compliance with rigorously strict standards due to the presence of volatile resins, and
• - as regards the manufacture of the parts, these are carried out on presses or in autoclaves, which involves a large number of manual operations, in particular due to the superposition of the layers of these pieces with a laminated structure, and therefore of the immobilization times of the machines which are also significant, which increases the energy cost.

• - il est adapté à être conformé manuellement à tout support métallique ou non, galbé ou non,
• - à performances égales, on obtient un gain de poids important et donc une réduction du coût de la matière nécessaire,
• - le découpage se fait simplement, à l'aide d'outils tranchants ordinaires, tels que scalpel, "cutter" et analogues,
• - les temps de fabrication et d'application sont courts, la fabrication étant effectuée en continu.

The object of the present invention is to provide a protection device resistant to the impact of projectiles and fragments or fragments of explosions and intended more particularly for the shielding of motor vehicles, which device meets the needs of the practice better than the devices aiming at the same goal previously known, in particular in that:

• - it is suitable for being manually shaped to any metallic support or not, curved or not,
• - for equal performance, a significant weight gain is obtained and therefore a reduction in the cost of the material required,
• - the cutting is done simply, using ordinary sharp tools, such as scalpel, "cutter" and the like,
• - The manufacturing and application times are short, the manufacturing being carried out continuously.

The subject of the present invention is a device for protecting a structure, more particularly constituted by a motor vehicle, against the impact of projectiles and fragments or fragments of explosions, said device being of the type having a laminated structure based on elastomer and fibers, preferably constituted by organic fibers of aromatic polyamide, which device is characterized in that said laminated structure comprises at least one flexible module consisting of a plurality of composite layers (or plies) superimposed, each composite layer comprising a textile intermediate layer made of said fibers and adhered on either side to a very thin film made of said elastomer, the various composite layers being joined together by vulcanization and their number being a function of the degree of flexibility desired for the module, and in that said module is able to be applied preferably by gluing, but also by screwing or riveting or other means suitable for any support, metallic or not, curved or not, in particular constituted by said structure to be protected or by another type of protection device known in itself already optionally fitted to this structure or by another module of the same type.

According to an advantageous embodiment of the device according to the invention, the number of said composite layers is between 5 and 20 and preferably between 5 and 10.

According to another advantageous embodiment of the device according to the invention, each thin elastomeric film adhered on either side relative to each textile layer, has a thickness of between 0.01 and 0.018 mm and an adhesion of between approximately 5.10 ² N / m and 29.10 ² N / m, and the percentage by weight of elastomeric product used in a given module is between 7% and 15% of the total weight of the module.

According to yet another advantageous embodiment of the device according to the invention, the glue connecting a module to the module which precedes it, looking in the opposite direction to that of propagation of the projectiles or ejection of the fragments, or directly to said support, is of the type having a sufficient elongation power to absorb part of the kinetic impact energy and good adhesion, in particular of the order of 49.10 ² N / m, namely an appropriate crosslinking rate , preferably between 1 and 20.

According to a preferred embodiment of the device according to the invention, it comprises a plurality of modules of the aforementioned type, at least one intermediate module of which comprises said textile layers made of fibers having a breaking strength and a number of warp and weft threads which are lower compared to at least one module preceding it, looking in the opposite direction to that of projectile propagation or ejection of the fragments, but which are higher compared to at least one module following it, if this one exists.

According to a preferred arrangement of this embodiment, the device comprises at least one so-called primary module, which is exposed to projectiles or fragments, and at least one so-called secondary module, which follows it while looking in the opposite direction to that of propagation of the projectiles or fragments ejection, which primary module has a titration between 1100 and 1680 dtex, a number of threads in warp and weft equal to or greater than 10.5 and a resistance to breakage in warp and weft equal or greater than 186.10 ³ N / m, while the secondary module has a titration of between 1680 and 3300 dtex, a number of threads in warp and weft equal to or greater than 3.7 and a breaking strength in warp and weft equal or greater 137-10 ³ N / m.

According to an advantageous embodiment of the device according to the invention, it comprises a plurality of modules of the aforementioned type, each of which has a titration of between 1100 and 1680 dtex, a number of threads in warp and weft equal or greater at 10.5 and a breaking strength in warp and weft equal to or greater than 186 · 10 ³ N / m.

In addition to the foregoing provisions, the invention also comprises other provisions, which will emerge from the description which follows.

It is recalled below some definition of ballistics which will be useful for a better understanding of what is exposed in the additional description which follows.

• . une onde longitudinale, qui se propage à la vitesse du son perpendiculairement à la direction de propagation du projectile et qui soumet donc la matière (contenue dans un plan perpendiculaire au chemin parcouru par le projectile) à une contrainte de traction proportionnelle à la vitesse du son; et
• . une onde transversale, qui se propage à la vitesse du projectile (donc à une vitesse inférieure) parallèlement à la direction de propagation du projectile et qui fait déplacer la matière perpendiculairement à l'axe des fibres, à savoir parallèlement au chemin parcouru par le projectile, ce phénomène étant plus connu sous le nom de "délaminage" ou "destratifi- cation".

It is known that, when a projectile hits an armor, a spherical wave arises at the point of collision. However, this wave breaks up into two successive waves, namely:

• . a longitudinal wave, which propagates at the speed of sound perpendicular to the direction of propagation of the projectile and which therefore subjects the material (contained in a plane perpendicular to the path traveled by the projectile) to a tensile stress proportional to the speed of sound ; and
• . a transverse wave, which propagates at the speed of the projectile (therefore at a lower speed) parallel to the direction of propagation of the projectile and which makes the material move perpendicular to the axis of the fibers, namely parallel to the path traveled by the projectile , this phenomenon being better known under the name of "delamination" or "destratification".

• . d'une part, avec les modules ayant des films à forte adhérence, à savoir supérieure à 39.10² N/m et un allongement à la rupture faible, les deux cas suivants se présentent:
  • - si la perforation du blindage est totale, aucun délaminage n'est observé;
  • - si la perforation est partielle, le délaminage apparaît dans un point situé entre 50 et 70% de l'épaisseur et la déformation de la partie arrière du dispositif est faible, tandis que
• - d'autre part, avec les modules ayant un film à faible adhérence, à savoir comprise entre 5.10² _N/m et 29.10² N/m, et un allongement élevé, la pénétration est partielle, le délaminage apparait dans un point situé entre 10 et 40% de l'épaisseur et la déformation de la partie arrière du dispositif est grande.

The various tests carried out on modules in accordance with the invention, described above, having a constant number of intermediate layers, identical textile weave and elastomeric films with different mechanical properties and adhesions, provided the following lessons:

• . on the one hand, with the modules having films with high adhesion, namely greater than 39.10 ² N / m and a low elongation at break, the following two cases arise:
  • - if the shielding perforation is complete, no delamination is observed;
  • - if the perforation is partial, delamination appears in a point between 50 and 70% of the thickness and the deformation of the rear part of the device is small, while
• - on the other hand, with the modules having a film with low adhesion, namely between 5.10 ² _N / m and 29.10 ² N / m, and a high elongation, penetration is partial, delamination appears at a point between 10 and 40% of the thickness and the deformation of the rear part of the device is large.

• . d'une part, à confirmer le rôle décisif du délaminage dans l'absorption de l'énergie cinétique du projectile, dont l'arrêt est déterminé par la nature et l'épaisseur du film élastomère; et
• . d'autre part, à penser que la contrainte maximum provoquant la rupture des fils se situe dans la face avant du dispositif, en sorte qu'à mesure que le projectile pénètre dans le blindage, notamment constitué par deux modules superposés selon l'invention, et s'écrase, le déplacement de la matière derrière l'onde transversale charge les fils du module secondaire et décharge les fils du module primaire.

These observations on the behavior of the shields in accordance with the present invention led to:

• . on the one hand, to confirm the decisive role of delamination in the absorption of the kinetic energy of the projectile, the stopping of which is determined by the nature and the thickness of the elastomeric film; and
• . on the other hand, to think that the maximum stress causing the breakage of the wires is located in the front face of the device, so that as the projectile enters the shielding, in particular consisting of two superimposed modules according to the invention, and crashes, the displacement of the material behind the transverse wave charges the wires of the secondary module and discharges the wires of the primary module.

It is therefore advantageous to replace the wires of the secondary module with wires having a lower breaking strength and a lower number of wires in warp and weft. In addition to the lightening of the carpet thus produced, this arrangement allows a reduction in the material cost.

It goes without saying that it would be possible to replace the secondary module with any sheet material capable of marrying a curved shape (namely, having a flexibility compatible with that of the primary module), provided that it has equivalent breaking strength properties.

• . un premier module placé en face avant, et donc avantageusement composé d'un tissu au nombre de fils relativement important et présentant une résistance en chaîne et trame élevée, dont le titrage est compris entre 1100 et 1680 dtex, la résistance à la rupture est supérieure ou égale à 186.10³ N/m de longueur, le nombre de fils en chaîne et trame est supérieur à 10,5; et
• . un deuxième module placé en face arrière, et donc avantageusement composé d'un tissu d'une résistance moins élevée et d'un nombre de fils en chaîne et trame réduit, dont le titrage est compris entre 1680 dtex et 3300 dtex, la résistance est au moins égale à 137·10³ _N/m, le nombre de fils en chaîne et en trame est supérieur ou égal à 3,7.

For the two reasons stated above, when the shielding according to the invention comprises several superimposed modules, this consists of at least two of such modules having characteristics and performances which differ in the above-mentioned direction; for example, the device according to the invention may include:

• . a first module placed on the front face, and therefore advantageously composed of a fabric with a relatively large number of threads and having a high warp and weft resistance, the titration of which is between 1100 and 1680 dtex, the breaking strength is higher or equal to 186.10 ³ N / m in length, the number of warp and weft threads is greater than 10.5; and
• . a second module placed on the rear face, and therefore advantageously composed of a fabric of lower resistance and of a reduced number of warp and weft threads, the titration of which is between 1680 dtex and 3300 dtex, the resistance is at least 137 · 10 ³ _{N /} m, the number of warp and weft threads is greater than or equal to 3.7.

Regarding the thickness of the elastomeric wire and its mechanical properties, both of them define essential conditions for the shielding performance. In fact, a film having a low adhesive power, for example of the order of approximately 5.10 ² _{N /} m to 29.10 ² N / m, allows delamination of the sheets of fabric, but in any event must retain its significant elongation capacity, while the increase in the thickness of the film reduces the path of the longitudinal wave and results in a greater penetration depth of the projectile; on the other hand, a thick film increases the confinement of the wires, which limits their elongation power and concentrates the stress in the impact zone, the wires being more subject to shear. Moreover, we also know that the longitudinal wave is all the more reflected as the number of warp and weft threads is reduced; however, the components of the reflected wave are superimposed on the components of the initial wave and break the wires in the impact zone, if the amplitude exceeds the resistance of the wires at this point; therefore, the lower the reflection of the wave, the greater the energy absorbed by the wires near the impact.

For this, the thickness of the film must advantageously be between 0.01 and 0.018 mm, which represents a percentage by weight relative to the total weight of the material used between 7 and 15%.

Its 100% modulus is between 108 N / m2 and 5.10 ⁸ N / m2.

The film elastomer is further advantageously formulated so as to exhibit flame retardant properties.

The thickness of each of said textile intermediate layers of each composite layer which is involved in the constitution of a flexible module according to the invention is preferably about 0.35 mm before the operation of adhering the textile layer , on both sides, to elastomeric films.

Obviously, after the bonding and vulcanization operations, the thickness of the textile layers decreases.

As regards the vulcanization of the modules according to the invention, this takes place, unlike the known methods for rigid and semi-rigid shields, under low pressure, in particular less than about 29.10 ⁴ Pa (= ₂ , 9 bar), and at high temperature, in particular between 150 and 170 ° C, which also implies a short holding time.

Although the shielding according to the invention rarely finds an application when used alone, on the other hand, thanks to its modularity, it can provide additional protection to an existing element, such as for example a body sheet, or even to high hardness metallic shielding.

It is also well known that the association of steel with "KEVLAR" reduces the penetration of a projectile. However, it is possible to improve the performance of such an assembly by certain arrangements in the assembly of these elements.

Indeed, tests carried out with a primary protection (thin sheet of 0.5 to 1 mm in mild steel intended for stamping) associated without bonding to the modules according to the invention, demonstrate that this assembly offers a power of lower stop, compared to assemblies whose devices are strongly bonded.

• . dans l'absence de collage, lorsqu'un projectile impacte la partie métallique, une partie de l'onde longitudinale se diffuse à grande vitesse dans la tôle sans être freinée, ce qui réduit les contraintes dans le module primaire;
• . lorsque la tôle est fortement collée sur le blindage souple et modulaire selon l'invention, elle résiste fortement à l'avancement du projectile, qui est ainsi ralenti; le blindage souple subit alors une déformation importante qui tend à mieux répartir la contrainte dans les fils, tandis que la déformation de la tôle charge les fils du module primaire dans une zone plus importante.

In this regard, some explanations can be provided, namely:

• . in the absence of bonding, when a projectile impacts the metal part, part of the longitudinal wave diffuses at high speed in the sheet without being braked, which reduces the stresses in the primary module;
• . when the sheet is strongly bonded to the flexible and modular shielding according to the invention, it strongly resists the advancement of the projectile, which is thus slowed down; the flexible shield then undergoes a significant deformation which tends to better distribute the stress in the wires, while the deformation of the sheet loads the wires of the primary module in a larger area.

To benefit from the advantages of bonding, the bonding adhesive between the superimposed modules must have good adhesion, in particular of the order of 49.10 ² N / m, and a sufficient elongation power to absorb part of the kinetic energy. To this end, a good compromise is found with an adhesive whose crosslinking rate is between 1 and 20.

By way of nonlimiting example are indicated below, in diagram form, some of the possible compositions of the modular shielding device according to the invention used alone and in cooperation with a steel sheet bonded on the front face, this sheet being of different thickness and simulating for example the sheet metal of the body of a motor vehicle.

Composition A refers to the case where on the front face is glued a sheet whose thickness is between 1 and 1.2 mm and composition B relates to the case where on the front face is glued a sheet whose thickness is between 0.5 and 0.7 mm, while composition C relates to the absence of sheet metal on the front face.

On the left vertical axis is indicated the number of composite layers involved in the composition of each of the modules, of which consists the shielding device.

In each case it is possible to stop a 9 mm armored projectile (it is a projectile in the shape of a warhead, with a lead core and a copper jacket) having a weight of 8.1 g, a speed of 380 m / sec, the weapon used having a length of 6 "(≅15, 24 cm).

The hatched rectangles refer to modules whose textile frame in "KEVLAR" has a titration of 3300 dtex, while the not hatched rectangles refer to modules whose textile frame in "KEVLAR" has a titration of 1100 dtex. On the top of each rectangle is indicated the total mass of the device in kg / m ² , while inside each rectangle is indicated the mass in kg / m ² of each of the corresponding modules of which the shielding device is made up.

• - le cas A correspond à un dispositif ayant une masse au m² de 3,3 kg/m² et constitué par un module:
  • . qui comporte 10 couches composites;
  • . dont l'armature textile a un titrage de 1100 dtex;
  • . dont la masse au m² est de 3,3 kg/m²; et
  • . qui coopère en face avant avec une tôle de 1 à 1,2 mm;
• - le cas B correspond à un dispositif ayant une masse au m² de 4,75 kg/m² et constitué par:
  • . un module primaire en face avant:
    • - qui comporte 15-5= 10 couches composites;
    • - dont l'armature textile a un titrage de 1100 dtex;
    • - dont la masse au m² est de 3,3 kg/m^?; et
  • . un module secondaire en face arrière:
    • - qui comporte 5 couches composites;
    • - dont l'armature textile a un titrage de 3300 dtex;
    • ^- dont la masse au ^m2 est de ^3,3 k^g/m²; et qui coopère en face avant avec une tôle de 0,5 à 0,7 mm;
• - le cas C correspond à un dispositif ayant une masse au m² de 6 kg/m² et constitué par:
  • . un module primaire en face avant:
    • - qui comporte 20-15= 5 couches composites;
    • - dont l'armature textile a un titrage de 1100 dtex;
    • - dont la masse au m² est de 1,65 kg/m²; et
  • . un module secondaire en face arrière:
    • - qui comporte 15 couches composites;
    • - dont l'armature textile a un titrage de 3300 dtex;
    • - dont la masse au m² est de 4,35 kg/m² _;
  
  ce dernier dispositif étant utilisé seul, à savoir sans tôle en face avant.

Summarizing the above, it is therefore clear that:

• - case A corresponds to a device with a mass per m ² of 3.3 kg / m ² and consisting of a module:
  • . which has 10 composite layers;
  • . whose textile reinforcement has a titration of 1100 dtex;
  • . whose mass per m ² is 3.3 kg / m ² ; and
  • . which cooperates on the front face with a sheet of 1 to 1.2 mm;
• - case B corresponds to a device with a mass per m ² of 4.75 kg / m ² and consisting of:
  • . a primary module on the front panel:
    • - which has 15-5 = 10 composite layers;
    • - whose textile reinforcement has a titration of 1100 dtex;
    • - whose mass per m ² is 3.3 kg / m ^? ; and
  • . a secondary module on the rear panel:
    • - which has 5 composite layers;
    • - whose textile reinforcement has a titration of 3300 dtex;
    • ^- whose mass per ^m2 is ^3.3 k ^g / m ² ; and which cooperates on the front face with a sheet of 0.5 to 0.7 mm;
• - case C corresponds to a device having a mass per m ² of 6 kg / m ² and consisting of:
  • . a primary module on the front panel:
    • - which has 20-15 = 5 composite layers;
    • - whose textile reinforcement has a titration of 1100 dtex;
    • - whose mass per m ² is 1.65 kg / m ² ; and
  • . a secondary module on the rear panel:
    • - which has 15 composite layers;
    • - whose textile reinforcement has a titration of 3300 dtex;
    • - whose mass per m ² is 4.35 kg / m ² _;
  
  the latter device being used alone, namely without sheet metal on the front face.

Now, given that the examples of compositions and combinations can be multiplied infinitely, it is clear that the advantage of the compositions and combinations which have just been described lies in the fact that they show some of the possible solutions. to stop a given projectile under given circumstances.

A variant of the solution described above, and applicable to low and medium power weapons (classes I to III), finds application for high speed bursts.

In the context of the present invention, by classes I, II and III is meant the classes relating to projectiles propelled by handguns, the speeds of which range from approximately 280 m / sec in class I to approximately 540 m / sec in class III.

It is well known that the "KEVLAR" cannot be used alone for very high speed projectiles, ie located beyond said class III. Indeed, beyond 500 to 550 m / sec, the material undergoes only a shear stress, the increase in the mass of material used does not result in a proportional reduction in speed.

However, the "KEVLAR" easily brakes low mass bursts at high speed, but it insufficiently brakes larger mass bursts at low speed.

The solution which is adopted in the context of the present invention, to overcome this drawback consists in forming flexible modules each consisting of a plurality of composite layers (or plies) of the above type each cooperating with a very thin metal strip which follows the corresponding composite layer looking in the opposite direction to that of projectile propagation or ejection of the fragments and which is also adhered, like said textile layer, on either side, to an elastomeric film of very low thickness, the different composite layers thus produced being joined together by vulcanization and their number being a function of the degree of flexibility desired for each module. In this case, the best ballistic performance is obtained with a module whose minimum titration of the textile weave in "KEVLAR" is 1100 dtex, the number of threads in warp and weft being high and in any case at least equal to 10.5 with a breaking strength of 186.10 ³ N / m or more in warp and weft, while the metal strip, in particular consisting of a high-strength steel strip, has a very small thickness, preferably between 0.03 and 0.1 mm - which contributes to keep the necessary characteristic of flexibility also with the variant in question - and a breaking strength which is greater than 4905.10 ⁵ Pa (= ₄₉₀₅ bar) as well as a Rockwell B hardness which is equal to or greater than 76. With regard to relates to the elastomeric film, it has characteristics identical to those of the module without metal strip.

However, the splinter performance is explained by the longitudinal wave better diffused in the metal, which has the effect of distributing the stresses more evenly. On the other hand, the strips, as in the case of a sheet placed only on the front face, undergo successive deformations which considerably slow down the speed and the penetration of the chip.

As is apparent from the above, the invention is in no way limited to those of its embodiments and of application which have just been described more explicitly; on the contrary, it embraces all the variants which may come to the mind of the technician in the matter without departing from the framework, or the scope, of the present invention.

Claims (11)

1. Device for protecting a structure, more particularly constituted by a motor vehicle, against the impact of projectiles and explosion fragments or fragments, said device being of the type having a laminated structure based on elastomer and fibers , preferably consisting of organic fibers of aromatic polyamide, which device is characterized in that said laminated structure comprises at least one flexible module consisting of a plurality of superimposed composite layers, each composite layer comprising a textile intermediate layer made of said fibers and adhered on both sides to a very thin film made of said elastomer, the different composite layers being joined together by vulcanization and their number being a function of the degree of flexibility desired for the module, and in that said module is suitable for application preferably by gluing, but also by screwing or riveting or other means yen suitable for any support, metallic or not, curved or not, in particular constituted by said structure to be protected or by another protection device of a type known per se already optionally fitted to this structure or by another module of the same type. 2. Device according to claim 1, characterized in that the number of said composite layers is between 5 and 20 and preferably between 5 and 10. 3. Device according to claim 1, characterized in that each thin elastomeric film adhered on either side with respect to each textile layer, has a thickness of between 0.01 and 0.018 mm and an adhesion of between approximately 5.10 ² N / m and 29-10 ² N / m, and the percentage by weight of elastomeric product used in a given module is between 7% and 15% of the total weight of the module. 4. Device according to claim 1, characterized in that the glue connecting a module to the module which precedes it, looking in the opposite direction to that of propagation of the projectiles or ejection of the fragments, or directly to said support, is of the type having sufficient elongation power to absorb part of the kinetic impact energy and good adhesion, in particular of the order of 4 ₉ · 10 ² _{N / m} , namely an appropriate crosslinking rate, preferably between 1 and 20. 5. Device according to claim 1, characterized in that it comprises a plurality of modules of the above type, of which at least one intermediate module comprises said textile layers made of fibers having a breaking strength and a number of son in warp and weft which are lower compared to at least one module which precedes it, looking in the opposite direction to that of propagation of the projectiles or ejection of the fragments, but which are higher compared to at least one module which follows it, if it exists. 6. Device according to claim 5, characterized in that the device comprises at least one so-called primary module, which is exposed to projectiles or fragments, and at least one so-called secondary module, which follows it while looking in the opposite direction to that of propagation of projectiles or ejection of fragments, which primary module has a titration of between 1100 and 1680 dtex, a number of threads in warp and weft equal to or greater than 10.5 and a breaking strength in warp and weft equal or greater than 186.10 ³ N / m, while the secondary module has a titration of between 1680 and 3300 dtex, a number of warp and weft threads equal to or greater than 3.7 and a breaking strength in warp and weft equal to or greater than 137.10 ³ N / m. 7. Device according to claim 1, characterized in that it comprises a plurality of modules of the aforementioned type, each of which has a titration between 1100 and 1680 dtex, a number of son in warp and weft equal to or greater than 10 , 5 and a breaking strength in warp and weft equal to or greater than 186.10 ³ N / m. 8. Device according to any one of claims 1 to 7, characterized in that, in particular when the latter must provide protection against splinters at high speed, said flexible module or modules each consist of a plurality of composite layers of the aforementioned type each cooperating with a very thin metal strip which follows the corresponding composite layer, looking in the opposite direction to that of propagation of the projectiles or ejection of the fragments and which is also adhered, like said textile layer, to on either side, to a very thin elastomeric film, the various composite layers thus produced being joined together by vulcanization and their number being a function of the degree of flexibility desired for each module. 9. Device according to claim 8, characterized in that the metal strips have a thickness preferably between 0.03 and 0.1 mm, a breaking strength greater than or equal to 4905 · 10 ⁵ Pa (= ₄₉₀₅ bar) and a Rockwell B hardness equal to or greater than 76, each module having a minimum titration of 1100 dtex, a number of warp and weft threads at least equal to 10.5 with a warp and weft breaking strength equal to or greater than 186.10 ³ N / m. 10. Device according to any one of Claims 1 to 9, characterized in that the elastomeric film has flame retardant properties. 11. A method of coating, using the flexible device according to any one of claims 1 to 10, of a structure to be protected against the impacts of projectiles and fragments or fragments of explosions, more particularly constituted by a vehicle automobile, the support of this flexible device being curved or not, metallic or not, and constituted by said structure to be protected or by another protection device of a type known per se already optionally fitted to this structure, which method is characterized in that the coating is done by gluing a flexible module to said support or a plurality of modules one after the other to this support and between them, each module being previously vulcanized continuously at low pressure and at relatively high temperature, in particular at a pressure below about 29-10 ⁴ Pa (= 2.9 bar) and at a temperature between 150 and 170 ° C, with short holding times.