WO2023214409A1

WO2023214409A1 - Ballistic armour

Info

Publication number: WO2023214409A1
Application number: PCT/IL2023/050448
Authority: WO
Inventors: Moshe Ravid
Original assignee: Rimat Advanced Techonologies Ltd
Priority date: 2022-05-02
Filing date: 2023-05-02
Publication date: 2023-11-09

Abstract

An armour cassette comprising a gel interlayer sandwiched between two plates.

Description

BALLISTIC ARMOUR

RELATED APPLICATIONS

[0001] This application claims benefit under 35 U.S.C. 119(a) of Israeli Patent Application No. 292878 filed May 2, 2022, and Israeli Patent Application No. 300732 filed February 16, 2023, the disclosures of which are incorporated herein by reference.

FIELD

[0002] Embodiments of the disclosure relate to providing armour configured to protect a target from damage by a high energy projectile/penetrator.

BACKGROUND

[0003] Armour for covering and protecting a target, such as a person, vehicle, or installation, against damage by a destructive high energy projectile, conventionally referred to as a projectile threat, functions to prevent kinetic energy that the projectile contains or generates by explosive detonation from reaching and damaging the target. A variety of different configurations of projectile threats for attacking targets and of armour for protecting the targets against attacks by the projectile threats under different scenarios and conditions of conflict are currently available and in use. For convenience of presentation, in the following discussion examples of the variety of armour and projectile threats are discussed with reference to armoured fighting vehicles (AFVs) such as tanks and armoured personnel carriers (APCs) as targets.

[0004] Projectile threats for use against AFVs are generally classified as kinetic energy (KE) projectile threats or chemical energy (CE) projectile threats. KE projectile threats, or KE projectiles, such as armour piercing discarding sabot (APDS) and armour piercing fin stabilized discarding sabot APFSDS, do not carry a chemical payload. The KE projectile threats typically comprise a heavy metal, long rod penetrator (LRP) that penetrates armour as a function of properties of the material from which the LRP is formed and the LRP kinetic energy at impact with the armour. CE projectile threats, or CE projectiles, carry a chemical payload that detonates with proximity to or upon contact with armour to form a penetrator or penetrators for penetrating the armour. In CE projectiles referred to as self-forging fragments (SFF) or explosively forged projectiles (EFP) the chemical payload detonates to form a penetrator from a metal liner typically formed from a mild steel or high purity copper (Cu) and accelerate the penetrator to penetrate armour. CE projectiles such as projectile threats referred to as high explosive anti-tank (HEAT) projectiles carry a warhead having a shaped charge that envelopes a contiguous metal liner. The shaped charge detonates upon contact with armour to explosively form and accelerate the liner into a high pressure hypervelocity jet of heated metal, typically of a high purity copper (Cu), for striking, penetrating, or perforating armour.

[0005] Armour to protect AFVs, and armour in general, operates to absorb and/or scatter kinetic energy that a projectile threat transmits to the armour to prevent complete penetration or perforation, hereinafter generically referred to as penetration, of the armour and subsequent damage to the target. Armour is conventionally classified as passive, reactive, or active. Passive armours typically comprise a combination of materials configured in any of various advantageous geometries to undergo violent disruption when impacted by a projectile threat and “passively” absorb and scatter energy transmitted to the armour by the projectile. By way of example, passive armour includes sloped armour, spaced armour, slat armour, and composite armour. Reactive armour undergoes a dynamic, reactive change responsive to impact by a projectile threat in addition to passive disruption and generally comprises a reactive material sandwiched between metal plates. In response to an impact by a projectile threat, the reactive material explodes or explosively deflagrates to rapidly change phase to a high pressure gas that accelerates the metal plates to violently collide with and deflect, absorb, and/or scatter energy of the projectile threat. Active armour uses sensors to detect an incoming projectile threat and responsive to detection operates to activate a soft kill system to misdirect an incoming projectile and/or a hard kill system to actively intercept the projectile by igniting an explosive or deflagration reaction that launches interceptors to physically engage the projectile.

[0006] For convenience of mounting, dismounting, and localization of damage due to impact by a projectile threat, armour is very often configured as relatively small area armour cassettes. Typical materials used in producing armour and add-on armour to provide armour with desired characteristics include various steels, for example, rolled homogeneous armour (RHA), high hard steel (HHS), ultra-high hard steel (UHH), Titanium (Ti) alloys, Magnesium (Mg) alloys, and/or Aluminum (Al) alloys, various ceramics, various fabrics, rubbers, glasses, and/or composites. SUMMARY

[0007] An aspect of an embodiment of the disclosure relates to providing armour, optionally configured as an armour cassette, comprising water absorbed in a hydrogel to protect a target against damage from a KE and/or a CE projectile threat. In an embodiment the hydrogel is encapsulated in an impervious skin or form fitting receptacle formed from a resilient or plastic material that is sandwiched between rigid optionally metal plates. The hydrogel advantageously comprises a relatively large amount of water content by weight in excess of about 70%. Advantageously the water content is equal to about 95% by weight. The hydrogel may comprise a substantially homogenous dispersion of gas filled voids having characteristic dimensions less than about 100 pm. In an embodiment the hydrogel comprises a substantially homogenous dispersion of microballoons having characteristic dimensions between about 40 pm and about 100 pm. Optionally, the hydrogel comprises a substantially homogenous dispersion of active energy components that release energy for interfering with a projectile threat when impacted by the projectile.

[0008] In an embodiment an armour cassette comprises an interlay formed from a partially polymerized polymer sandwich between first and second, optionally metal plates. Optionally at least one of the plates comprises at least two regions characterized by different thickness.

[0009] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE FIGURES

[0010] Non-limiting examples of embodiments of the disclosure are described below with reference to figures attached hereto that are listed following this paragraph. Identical structures, elements or parts that appear in more than one figure are generally labeled with a same numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are chosen for convenience and clarity of presentation and are not necessarily shown to scale.

[0011] Fig. 1 schematically shows a perspective view of an armour cassette comprising a hydrogel in accordance with an embodiment of the disclosure; [0012] Figs. 2A and 2B schematically show cross section views of the armour cassette shown in Fig. 1 that illustrate reaction of the cassette to impact by a KE threat, in accordance with an embodiment of the disclosure;

[0013] Fig. 3 A schematically shows a rear plan view of an armour cassette 120 comprising an interlayer formed from a partially polymerized polymer, in accordance with an embodiment of the disclosure;

[0014] Figs. 3B-3D schematically show cross section views of the armour cassette shown in Fig. 3 A, in accordance with an embodiment of the disclosure; and

[0015] Fig. 4 schematically shows a cross section view of a louver type armour module comprising a plurality of armour cassettes shown in Figs 3A-3D, in accordance with an embodiment of the disclosure.

DETAILED DESCRIPTION

[0016] In the discussion, unless otherwise stated, adjectives such as “substantially” and “about” modifying a condition or relationship characteristic of a feature or features of an embodiment of the disclosure, are understood to mean that the condition or characteristic is defined to within tolerances that are acceptable for operation of the embodiment in an application for which it is intended. Wherever a general term in the disclosure is illustrated by reference to an example instance or a list of example instances, the instance or instances referred to, are by way of nonlimiting example instances of the general term, and the general term is not intended to be limited to the specific example instance or instances referred to. The phrase “in an embodiment”, whether or not associated with a permissive, such as “may”, “optionally”, or “by way of example”, is used to introduce for consideration an example, but not necessarily required, configuration of possible embodiments of the disclosure. Each of the verbs, “comprise” “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of components, elements or parts of the subject or subjects of the verb. Unless otherwise indicated, the word “or” in the description and claims is considered to be the inclusive “or” rather than the exclusive or, and indicates at least one of, or any combination of more than one of items it conjoins.

[0017] Fig. 1 schematically shows a perspective view of an add-on armour cassette, 20 comprising water absorbed in a hydrogel to protect a target against damage from a KE and/or a CE projectile threat, in accordance with an embodiment of the disclosure.

[0018] Cassette 20 comprises a front plate 22, conventionally referred to as a strike plate, and a rear plate 24 that sandwich between them a hydrogel interlayer 30 comprising a hydrogel 32 encapsulated by an impervious “skin” 34. Front plate 22, conventionally referred to as a strike plate, is the plate which faces a direction from which a penetrator is expected to impact cassette 20 when the cassette is mounted on an AFV. In Fig. 1 skin 34, which completely encapsulates hydrogel 32, is cutaway to show only edges of the skin. Skin 34 may be formed from any suitable material or combination of materials, that renders mechanical integrity of the skin relatively stable for a range of temperatures from about -40°C to about +95°C. Materials for producing skin 34 may include a thermoplastic resin, thermosetting resin, rubber, latex, polyurethane, and/or polyurea. In an embodiment hydrogel 32 is preformed to a shape that is mechanically stable and skin 34 is formed by spraying material from which the skin is formed onto the shaped hydrogel or by dipping the hydrogel shape into a bath of the skin material. Optionally skin 34 is preformed, for example by vacuum forming or injection molding skin material, and hydrogel 32 is formed in and to fill the preformed skin by adding water to a hydrogel powder placed in the skin, and after filling sealing the skin.

[0019] Front, plate 22, hydrogel interlayer 30 and back plate 24 are securely held in place by, optionally six, flanged bolt sleeves 40 through which bolts (not shown) may be inserted to mount cassette 20 to an add-on armour structure for example for an AFV. An enlarged cross section view of a sleeve 40 coupled to plates 22 and 24 is shown in an inset 80. As shown in the inset each sleeve optionally comprises male and female flanged bolt bushings 41 and 42 respectively that are press fit into holes 26 in the plates and to each other. Hydrogel interlayer 30 is formed to substantially completely, fill the space between front and rear plates 22 and 24 that surrounds sleeves 40.

[0020] In an embodiment hydrogel 32 has a water content by weight in excess of about 70%, 80%, or 90%. Advantageously the water content is equal to about 95% by weight. The hydrogel may comprise a substantially homogenous dispersion of micro-inclusions represented by flecks 36. In an embodiment the micro inclusions are configured to amplify and accelerate generation of pressure in hydrogel 32 caused by energy transferred to the hydrogel from impact with a penetrator and to thereby increase magnitude and velocity of bulging of front and back plates 22 and 24 caused by the pressure. The increase in magnitude and velocity of the bulging of plates 22 and 24 increase the mass efficiency of cassette 20 and the effectiveness of the plates in disrupting the penetrator and dispersing the penetrator kinetic energy. In an embodiment the inclusions comprise gas-filled voids having characteristic dimensions optionally less than about 100pm (micrometers), about 75 pm, or about 50pm. In an embodiment the inclusions comprise gas filled microballoons, such as gas filled phenolic microballoons, having characteristic dimensions between about 40 m and about 100 pm. Optionally the inclusions comprise active energy components, such as Magnesium particles, for example in powder form, that release energy for interfering with a projectile threat when perforated by the projectile.

[0021] By way of numerical example, in an embodiment cassette 20 may have a height H equal to about 400 mm, width W equal to about 240 mm, and overall thickness T between about 10 mm and about 25 mm. Front plate 22 may have thickness Tf between about 2 mm and about 10mm, rear plate 24 thickness T_r between about 1 mm and about 5 mm, and interlayer 30 a thickness Tg between about 3 mm and about 10 mm. Male and female bushings 41 and 42 may be formed from stainless steel having wall thicknesses between 0.4 and 1 mm.

[0022] Figs. 2A and 2B schematically show cross section views of cassette 20 interacting with an LRP penetrator 100 having a pointed tip 101 in accordance with an embodiment of the disclosure. Fig. 2A schematically shows penetrator 100 having a strike velocity Vg directed along a line of sight LOS that makes an angle a to a normal “n” of the plate just at impact with front plate 22 of cassette 20. Fig. 2B schematically illustrates reaction of cassette 20 after penetrator 100 impacts and penetrates front plate 22 of cassette 20. Upon tearing into and through front plate 22, tip 101 undergoes violent deformation and blunting as schematically indicated by numeral 102 and generates an extreme high pressure zone 32JJ in hydrogel 32 that rapidly expands to cause bulging and local acceleration to velocities Vf and V_r of front and back plates 22 and 24 in regions 22g and 24g. The accelerated bulging increases the mass efficiency of the front and rear plates and together with the spatial distribution of pressure in pressure zone 32JJ destroys and breaks up the physical integrity of penetrator 100 and disperses and deflects kinetic energy and propagation of residual pieces of the penetrator away from the LOS direction. In an embodiment the energy and residual pieces may be deflected at advantageous yaw angles greater than three degrees, at which angle deflections contribute substantially to reducing penetration of a penetrator. Fig. 2B schematically indicates a trajectory 120 deflected from LOS along which break-up pieces 103 of penetrator 100 are dispersed and propagate after penetration of cassette 20.

[0023] Whereas in the above discussion an armour cassette in accordance with an embodiment of the disclosure is described as comprising a hydrogel interlayer, embodiments of the disclosure are not limited to hydrogels. Gels other than hydrogels may be used to provide an armour cassette in accordance with an embodiment. By way of example a partially polymerized plastic gel such as a polyurethane viscoelastic polymer integrally formed with its own enveloping impervious skin may be used as an interlayer for an armour cassette in accordance with an embodiment of the disclosure. Optionally the polyurethane interlayer has an adhesive on the skin for adhering the interlayer to a plate of the cassette.

[0024] Figs. 3A-3D schematically show a rear plan view (Fig. 3A) and cross section views (Figs. 3B, 3C, 3D) of an armour cassette 120, comprising, as shown in the cross section views, an interlayer 150 formed from a partially polymerized polymer sandwiched between a first plate 122, optionally as shown in the figures, having at least two regions of different thickness and a second plate 126 having an optionally uniform thickness, in accordance with an embodiment of the disclosure. Fig. 3A shows the rear view of armour cassette 120 as seen facing second plate 126. Fig. 3B shows a cross section of armour cassette 120 in a plane A-A indicated in Figs. 3A and 3B. Fig. 3C shows a cross section of armour cassette 120 in a plane B-B indicated in Figs. 3A and 3C. Fig. 3D shows a cross section of armour cassette 120 in a plane C-C indicated in Figs. 3 A and 3D.

[0025] Fig. 3B clearly shows variable thickness first plate 122, second plate 126 and interlayer 150 sandwiched between the plates. Plates 122, 126, and interlayer 150 are optionally held together by flanged bolt sleeves 140 that are similar to flanged bolt sleeves 40 shown in Fig. 1, through which, optionally 1/4 inch (1/4”) grade 5 steel, bolts (not shown) may be inserted to secure plates 122 and 126 and interlayer 150 together and/or mount armour cassette 120 to an armour add-on structure. In an embodiment first plate 122 comprises first and second regions 123 and 124 respectively. First region 123 is a reinforced region having a greater thickness than second region 124 and optionally extends from a first, “top” end 122T of the plate to a bounding edge 123E located between the top end and a second bottom end 122B of the plate. In an embodiment first plate 122 may be integrally formed as a single piece by any of various forming processes, such as optionally by way of example by forging and tempering, machining or sintering to provide regions 123 and 124 of different thickness. In an embodiment, first plate may be formed by structural integrating a uniform thickness plate and a second smaller plate. The smaller plate may be fixed to the larger plate by any of various suitable means, such as by way of example, bolting, riveting, or gluing. Optionally, as shown in the cross section views of Figs. 3B-3D, first plate 122 is formed having a recess configured to nest interlayer 150 and second plate 126.

[0026] Optionally, first plate 122 functions as a front, strike plate of armour cassette 120 and second plate 126 functions as a rear plate of the armour cassette. In an embodiment strike plate 122 is formed from a high hard steel (HHS), and rear plate 126 is formed from an ultra-high hard steel (UHH). Partially polymerized interlayer 150 is optionally formed from, by way of example a SHOCKtec® or similar type Gel. In an embodiment partially polymerized interlayer 150 may be impregnated with another material such as by way of example micro-inclusions that amplify and accelerate generation of a high pressure gas phase of material comprised in interlayer 150 when energy is transferred to the interlayer from impact with a penetrator. Optionally, interlayer 150 may be a layered, composite interlayer, comprising at least two layers of different material. For example, a composite interlay in accordance with an embodiment may comprise a partially polymerized polymer layer and a hydrogel layer or other material that accelerates generating a high pressure gas phase from material in the interlayer.

[0027] By way of non-limiting numerical example, dimensions of armour cassette 120 are as shown in the figures. Optionally armour cassette is rectangular having a width equal to about 200 mm and height equal to about 400 mm. Reinforced region 123 of strike plate 122 has thickness equal to about 7 mm and extends about 140 mm from top end 122T towards bottom end 122B of strike plate 122. Region 124 of strike panel 122 optionally has thickness equal to about 2.4 mm. Interlayer 150 has thickness optionally between about 3 and about 6.5 mm (between about 1/8” - 1/4”) and rear plate 126 thickness optionally equal to about 2.0 mm.

[0028] In an embodiment of the disclosure a plurality of armour cassettes 120 are assembled into a spaced louver type armour module 160 suitable for mounting to an AFV and schematically shown in a cutaway cross section view in Fig. 4. Louver type armour module 160 comprises a striking panel 161 and a rear panel 162 that support between them a plurality of optionally equally spaced apart armour cassettes 120. The armour cassettes are positioned with reinforced regions 123 of their respective strike plates 122 facing striking panel 161 of louver type armour module 160. The armour cassettes are angled so that when armour module 160 is mounted to a AFV they protect, a normal to their strike plates 122 make a NATO angle a, where optionally a > 60° with the line of sight

[0029] Descriptions of embodiments of the invention in the present application are provided by way of example and are not intended to limit the scope of the invention. The described embodiments comprise different features, not all of which are required in all embodiments of the invention. Some embodiments utilize only some of the features or possible combinations of the features. Variations of embodiments of the invention that are described, and embodiments of the invention comprising different combinations of features noted in the described embodiments, will occur to persons of the art. The scope of the invention is limited only by the claims.

Claims

1. An armour cassette comprising: a first plate; a second plate; and a gel interlayer sandwiched between the plates.

2. The armour cassette according to claim 1 wherein the gel interlayer comprises a hydrogel.

3. The armour cassette according to claim 2 wherein the water content of the hydrogel by weight is in excess of 70%

4. The armour cassette according to claim 3 wherein the water content of the hydrogel by weight is equal to about 95%

5. The armour cassette according to any of the preceding claims the gel comprises a viscoelastic polymer.

6. The armour cassette according to claim 5 wherein the polymer is partially polymerized.

7. The armour cassette according to claim 6 wherein the partially polymerized polymer comprises a SHOCKtec® gel.

8. The armour cassette according to any of the preceding claims wherein the interlayer comprises at least two layers each comprising a different gel.

9. The armour cassette according to any of the preceding claims wherein the gel interlayer comprises micro-inclusions configured to increase the mass efficiency of the armour cassette.

10. The armour cassette according to claim 9 wherein the micro-inclusions comprise gas- filled voids.

11. The armour cassette according to claim 9 or claim 10 wherein the micro-inclusions comprise gas filled microballoons.

12. The armour cassette according to any of claims 9-11 wherein the micro-inclusions comprise active energy components.

13. The armour cassette according to claim 12 wherein the active energy components comprise Magnesium particles.

14. The armour cassette according to any of the preceding claims wherein the first plate comprises at least two regions having different thicknesses.

15. The armour cassette according to claim 14 wherein the first plate is integrally formed as a single piece.

16. The armour cassette according to claim 14 wherein the first plate is formed by structurally integrating two plates formed independently of each other.

17. An armour module housing a louvered configuration of armour cassettes according to any of the preceding claims.