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(11) | EP 2 233 877 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Ballistic element and armoured structure incorporating the same |
| (57) A ballistic element (1) with sided and/or overlapped ceramic tiles (3) sided and
an armoured structure (10) incorporating them provides an optimal compromise between
projectile penetration resistance and thickness, and it comprises at least two overlapped
layers (4, 5) formed by sided ceramic tiles, between said at least two layers (4,
5), an interface being provided between said at least two layers (4, 5), said interface
comprising a space (7) filled with a elastomeric material and being tilted with respect
to the longitudinal and transversal development of the ballistic element.
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[0001] The present invention relates to a ballistic element, i.e. to an anti-ballistic protective panel used for forming an armoured structures for providing protection to fixed or mobile apparatus from penetrating projectiles or from splinters deriving from explosive warhead.
[0002] Fixed apparatus means e.g. a protective structure for block posts, guard post, casements and so on. Mobile apparatus means any ground, air or naval vehicle such as armoured cars, tanks, aeroplanes, helicopters, ships and so on.
[0003] These elements are normally formed by a support frame, normally metallic, and by a ceramic armoured structure incorporating a plurality of sided ceramic tiles and a filler, e.g. elastomeric or polymeric, possibly containing fibres.
[0004] The metallic frame can consists of a composite coating, e.g. a rubberized fabric or pre-impregnated with a resin.
[0005] Together with the ceramic layer a support layer could be provided for dispersing impact energy, known as backing. Normally, such dispersion layer is place at the back side of the panel, i.e. the one opposed to panel's face exposed to the impact with projectiles, slivers and splinters.
[0006] A factor which can limit the use of the ballistic elements in general is their weight, that should not exceed certain limits, above all when these elements are applied to mobile means.
[0007] In fact, an excessively heavy armoured car two to its protective panels could not have enough acceleration or handiness. A helicopter or an aeroplane could be excessively limited in their load capacity if the armour were too heavy.
[0008] For this reason, in order to reduce the weight, it is necessary to contain the panels thickness. Nevertheless, the penetration strength is strongly dependent on the thickness itself.
[0009] Such parameter is not as relevant as in the fixed structures, but it is anyhow desirable to have a stronger protection, the thickness of the ballistic element being the same.
[0010] In order to overcome this drawback, it is moreover necessary to consider the way in which the shock wave of a projectile propagates along the thickness of an armoured structure.
[0011] The technical problem underlying the present invention consist in overcoming the problems which limits the spreading of ballistic elements and of the armoured structures containing them.
[0012] Such problem is solved by an armoured element as above defined, comprising at least two overlapping layers formed by sided ceramic tiles, an interface being provided between said at least two layers, said interface comprising a space filled with an elastomeric material and having a tilt with respect to longitudinal and/or transverse development of the armoured structure.
[0013] The invention refers to an armoured structure as above mentioned, incorporating a ballistic element according to the previous definition.
[0014] The ceramic tiles forming the ballistic element could be anyhow shaped, i.e. for example, they could be substantially flat and optionally squared, rectangular, triangular or hexagonal and realized e.g. in an alumina or Silicon or Boron carbide based sintered material or other similar materials. The elastomeric material could be vulcanized rubber, but can also advantageously consist of thermoplastic or thermosetting polymers, of vulcanized rubberized fabrics, pre-impregnated fabrics (prepreg) with thermosetting resins and so on.
[0015] The operating principle of the armoured structure consists in inducing a substantial diffraction of the shock wave deriving from the impact of a projectile, diffraction provided in correspondence of said interface owing the partial fragmentation of the ceramic layers, the entity of fragmentation varying from the projectile entry face to the rear region, i.e. the other side of the elastomeric interface, and causing the greater expansion of the shock wave due to the enlargement of wave front itself.
[0016] Also a substantial refraction of the shock wave when passing between the ceramic material and the elastomeric interface contributes to the expansion. Accordingly, a decrease of the pressure locally exerted next to the impact point corresponds to such expansion.
[0017] Moreover, the tilted surface produces a substantial destabilization of the incident projectile, crossing the ceramic layers next to the first one with a greater penetration section, and thus less effective in terms of penetration depth.
[0018] Moreover it should be noted how the elastomeric material has the ability to keep the ceramic material together even if it is fragmented, thus preventing a drastic loss of functionality of the panel.
[0019] It is also obvious that by improving the ceramic elements penetration resistance the thickness of the rear residual energy absorption part can be reduced, thus providing a reduction in the whole ballistic panel.
[0020] The present invention will be described according to a preferred exemplificative embodiment of a ballistic element, given by way of a non-limiting example, with reference to the annexed figures, wherein:
- figure 1 is a perspective view showing in a schematic and exemplificative way a ballistic element according to the present invention;
- figure 2 shows a cross section and partially exploded view of the ballistic element of figure 1;
- figure 2A shows a detail of a possible coupling between different ceramic layers in the structure of figure 1;
- figure 3 shows a partially exploded plan view vista of an armoured structure incorporating ballistic elements of figure 1;
- figure 4 shows a cross section view of an alternative embodiment of the ballistic element shown in figure 2;
- figure 5 shows a plan view of the ballistic element of figure 4; and
- figure 6 shows a cross section view of ballistic elements of figure 1 incorporated in an armoured structure.
[0021] With reference to the figures, a ballistic element is overall shown with the reference number 1.
[0022] Sizes, shape and the number of ceramic tiles of the element shown are merely arbitrary and are only exemplificative. Therefore, it is intended that the ballistic element 1 could be anyhow shaped and sized and also be curved owing to the shape of the ceramic tiles.
[0023] The armoured structure composed by more of said elements 1 is wrapped in a adhesive layer 12 allowing to assemble a plurality of tiles made of ceramic material together with other elements of a ballistic panel that will be better described in detail in the following.
[0024] The ceramic material is preferably containing a sintered material such as alumina, or other materials such as carbides, nitrides and other similar materials.
[0025] A suitable material for this purpose is a ceramic known with the trade name of CERASHIELD, manufactured by COORSTEK. It should be understood that any other ceramic material suitable for this kind of application can be used.
[0026] The ballistic element 1 is substantially formed by two overlapped ceramic layers, each formed by an arrangement of ceramic tiles 3.
[0027] Such element 1 thus comprises a first layer 4 formed by sided ceramic tiles 3, forming the exposed layer in correspondence of the front side of the element 1, i.e. the one meant to be exposed to possible projectiles, slivers, splinters and so on.
[0028] Moreover, the element 1 comprises a second layer 5 formed by sided ceramic tiles 3 above the previous layer, in correspondence of the rear side of the element 1, not shown in figure 1.
[0029] The tiles 3 of each layer are separated by escapes 6, or an interface with minimum or null width, for providing the more possible continuity of each layer 4, 5.
[0030] With reference to figures 2 and 3, said escapes 6 of the first and of the second layer are not overlapped, as the tiles 3 of each layer 4, 5 are disposed substantially staggered between them. This could obviously involve tiles with different sizes disposed in correspondence of the edges of the element 1, in order to compensate such staggered arrangement.
[0031] With reference then to figures 4 and 5, it is shown a simplified arrangement, wherein the escapes are actually overlapped.
[0032] In both the above mentioned versions, said layers 4, 5 are overlapped, defining an interface between them comprising a space 7 filled with a shim of elastomeric material.
[0033] The tiles 3 shape, and in particular the shape of the facing and conjugate surface of the tiles 3 of the two layers, is such that said interface is continuously tilted with respect to the longitudinal and transversal development of the element 1 and thus of the armoured structure composed therefrom, as well as with respect to the vertical of said longitudinal and transversal development, substantially concordant, at least in principle, with the firing direction of the projectiles that will impact the armoured structure.
[0034] Said continuous tilt is obtained by the fact that said tiles conjugate surfaces are tilted with reference to the longitudinal and/or transversal development of each tile.
[0035] In the exemplificative embodiment shown in figures, said surfaces are substantially bossed, with portions with specular tilt the one to the other.
[0036] In other words, the surfaces facing the tiles 3 of said layers 4, 5 has projections and recesses, e.g. tips, which are respectively complementary so as to form a tilted interface substantially continuously.
[0037] Accordingly, said projections and said recesses serve also as guides for assembling the tiles.
[0038] For a matter of advantageousness, said projections and said recesses could have an identical pattern, infinitely repeated on the entire surface of the sided layers 4, 5.
[0040] In the exemplificative embodiments of figures 1 to 5, the projections and recesses shape is substantially a cusp, i.e. a pyramid with a base that may contain the whole tile 3 extension.
[0041] When the tile is substantially squared and thus the cusp is formed by a four triangular faces pyramid.
[0042] With reference to figure 2A, the squared tile 3 has four square based pyramid shape cusps 8 on the face of the tile intended to be directed towards the complementary tile thereof. The complementary tile 3 will therefore have four complementary recesses.
[0043] It should be anyhow comprised that the cusp shape is merely one of the possible shapes suitable for providing a continuously tilted interface surface.
[0044] Another example is provided by isosceles triangular-shaped saw-tooth sections, defining linear edges, rather than apex as in the cusp-shaped solution. The saw tooth can also has a different profile, e.g. a right triangle.
[0045] With reference to figure 6, it is now described an armoured structure 10 incorporating the ballistic element 1 previously described with reference to figures 1 to 3. Nevertheless, the same description can be easily adapted to a skilled person of the element described with reference to figures 4 and 5.
[0046] Then, the structure 10 comprises a ballistic element 1 that, in the present example, is shaped by the layers of the overlapped tiles 3 and separated by a interface preferably in an material elastomeric.
[0047] Moreover it comprises a coating which, in the present exemplificative embodiment, it is formed by a flexible coating 11 wrapping the entire structure 1, having in correspondence of its front and rear faces, an adhesive layer 12.
[0048] In correspondence of said rear side, on the adhesive layer 12, a dispersion layer 13 or backing is placed, suitable for absorbing the energy associated to a projectile impact.
[0049] Such dispersion layer 13 can be manufactured in many ways. E.g., it can comprise layers in pre-impregnated aramidic fabric, in particular Kevlar®, cured in autoclave or rubberized aramidic fabric, vulcanized in autoclave.
[0050] The coating has the function of a frame and can be realized in pre-impregnated or rubberized aramidic fabric, cured or vulcanized in autoclave. It is placed in a such way that to completely wrap the armoured structure 10 and the backing 13, the latter having a further adhesive layer 12 on its rear side.
[0051] As previously illustrated, if the elastomeric material, the adhesive, the coating and optionally the backing itself share e.g. the rubberized component, they could become integral the one to the other in a successive vulcanization step.
[0052] It should be obviously understood that said front side could be covered by a covering layer, having an aesthetic function, mimetic and/or protective. It can be formed by a metallic plate, by a high strength fabric layer, by a pre-impregnated material layer and so on, or by a combination of two or more of the above mentioned covering layers. The elastomeric material could be vulcanized rubber, thermoplastic or thermosetting polymers, or it can comprise vulcanized rubberized fabrics, pre-impregnated fabrics (prepreg) with thermosetting resins and so on.
[0053] For example such fabric could be a Kevlar®, rubberized or impregnated with suitable materials fabric.
[0054] The tilt of said interface could be any, provided that it is significantly different from 90°. A perfectly suitable tilt could be comprised between 10° and 80°.
[0056] To the above described ballistic element and armoured structure incorporating them a person skilled in the art, in order to satisfy further and contingent needs, could effect several further modifications and variants, all however encompassed in the protective scope of the present invention, as defined by the appended claims.
1. A ballistic element (1) comprising ceramic tiles (3), characterized by having at least two overlapped layers (4, 5) formed by ceramic tiles, an interface
being provided between said at least two layers (4, 5), said interface comprising
a space (7) filled with an elastomeric material and being tilted with respect to the
longitudinal and transversal development of the ballistic element.
2. The ballistic element (1) according to claim 1, wherein the ceramic tiles (3) have
exposed surfaces which are substantially plane and parallel.
3. The ballistic element (1) according to claim 1 or 2, wherein the ceramic tiles (3)
are squared, rectangular, triangular or hexagonal shaped.
4. The ballistic element (1) according to any of the preceding claims, wherein said ceramic
material is in particular alumina-based.
5. The ballistic element (1) according to any of the preceding claims, wherein said elastomeric
material separating the layers (4, 5) could be vulcanized rubber, thermoplastic or
thermosetting polymers, vulcanized rubberized fabrics, or pre-impregnated fabrics
(prepreg) with thermosetting resins.
6. The ballistic element (1) according to any of the preceding claims, wherein the tiles
(3) of each layer (4, 5) are separated by escapes (6), the tiles (3) of each layer
(4, 5) being arranged so that they are substantially staggered.
7. The ballistic element (1) according to any of the preceding claims, wherein said tilt
is continuous and it is realized by conjugate surfaces which are tilted with respect
to the longitudinal and transversal development of the each tiles (3).
8. The ballistic element (1) according to claim 7, wherein the facing surfaces of the
tiles (3) of said overlapped layers (4, 5) have projections and recesses that are
respectively complementary, e.g. being substantially cusp shaped (8), so that they
form a tilted interface in a substantially continuous way.
9. The ballistic element (1) according to claim 8, wherein said projections and said
recesses have an identical pattern, infinitely repeated on the entire surface of the
facing layers (4, 5).
10. An armoured structure (10) incorporating a ballistic element of any of the preceding
claims, further comprising a coating for said structure, formed by a flexible coating,
in an aramidic pre-impregnated or rubberized fabric, cured or vulcanized in autoclave.
11. The armoured structure (10) according to claim 10, having a front side, i.e. exposed
to projectiles, and a rear part having an energy dispersing shim (13), in contact
with said armoured ceramic structure, and that can comprise a layer made of aramidic
pre-impregnated fabric, in particular Kevlar®, cured in autoclave or of aramidic rubberized fabric, vulcanized in autoclave, wrapped
by said coating.
12. The armoured structure (10) according to claim 11, wherein the elastomeric material,
an adhesive (12) on the faces of the armoured structure (1) and of said dispersion
layer (13), the flexible coating and optionally said dispersion layer, share the same
rubberized component, thus becoming integral to one to the other, in a successive
vulcanization step.