IL282038B2 - Fragile reactive protective armor - Google Patents

Description

41188/20 FRAGILE REACTIVE PROTECTIVE ARMOR Field of the Invention The present invention relates to reactive protective armor. More particularly, the invention relates to reactive armor comprising fragile internal elements.

Background of the Invention Reactive armor has been used since the 1970s to defend against threats such as hollow charges, projectile forming charges and kinetic energy penetrators. While different types of reactive armors exist, their common characteristic is that, when hit by a threat, they activate a charge that "reacts" by propelling a mass, typically a heavy metal plate, toward the threat, thereby neutralizing it or at least significantly reducing its ability to penetrate the target protected by the reactive armor.

One disadvantage of prior art reactive armor is its weight, which makes it unsuitable as protection for relatively light vehicles, which cannot conveniently carry the weight.

Another disadvantage of existing reactive armors is that while operating in the way described above may provide effective protection, is that the mass propelled by the charge activated inside the reactive armor outwardly may cause substantial damage to the surroundings and, of course, if activated in the vicinities of live personnel, may cause fatal injuries. Moreover, while reactive armor used in the art may be effective to neutralize the threat, it does not prevent fragments from the neutralized threat and from its own body to spread out into the surroundings, once again endangering people and equipment. It is therefore clear that it would be highly desirable to provide a reactive armor that does not possess the abovementioned disadvantages.41188/20 It is an object of the present invention to provide reactive armor that obviates the disadvantages of the prior art, which is relatively lightweight, and is capable of affording active protection without extensive damages to the surroundings.

It is another object of the invention to provide such reactive armor, which does not allow fragments of the armor itself or of the neutralized threat to escape and endanger the surroundings.

Other objects and advantages of the invention will be better understood through the description of embodiments thereof.

Summary of the Invention In one aspect, the invention relates to reactive armor for defeating threats, comprising one or more fragile reactive plates contained in an outer housing, the void space of said housing being filled with a polymeric foam. Typically, the fragile reactive plates consist of reactive material sandwiched between two fragile layers.

In one embodiment the fragile material is selected from among glass, glass-ceramic, ceramic, or their combinations. In another embodiment the fragile material is a polymer.

Examples of suitable polymers for the reactive armor of the invention include polyurethane, expanded polystyrene (EPS), extruded polystyrene (XPS), preformed polyisocyanurate, and spray polyurethane (SPF).

Suitable reactive materials adapted for use with reactive armors are known to the skilled person. Examples of reactive materials suitable for use in the reactive armor of the invention include C4, LF2, and LBR.41188/20 The reactive arm or of the invention includes a number of parts enclosed in one device. In some embodiments those parts are fixed using non-metallic fastening elements. Suitable fastening elements may comprise, for instance, nuts and bolts.

Brief Description of the Drawings In the drawings: Fig. 1 is a side-cross-sectional view of a device according to one embodiment of the invention; Fig. 2 is a front view of the device of Fig. 1 with lid removed; Fig. 3 is a perspective view of the device of Fig. 1 when closed; Fig. 4 is a cross-section of the device of Fig. 3 taken along the AA plane; Fig. 5 is a rotated view of the cross-section of Fig. 4; Fig. 6 is a perspective view of the interior of Fig. 3 with walls removed; Fig. 7 (A - D) show an embodiment in which cassettes are fixed to the external shell of the module with bolts; Fig. 8 shows the device of Fig. 1 in front view, after it was foam-filled; Fig. 9 (A and B) shows manufacturing stages of the device of Fig. 8; Fig. 10 shows a cassette adapted to be used in a device of the invention; Fig. 11 is a photograph of a device of Fig. 1, after the reactive armor of an adjoining cassette has been activated by a threat; and Fig. 12 (A and B) show an experimental setup described in greater detail hereinafter, before and after an experiment.41188/20 Detailed description of embodiments of the Invention Fig. 1 shows a side cross-section of a device 100 according to one specific embodiment of the invention. The device has a hollow body 101 (also referred to herein as "housing" or "outer housing"), sealed with a lid 102. Hollow body 101 houses a plurality of reactive cassettes, 103, 104 and 105. The positioning of cassettes 103, 104 and 105 is also seen in Fig. 2.

Fig. 3 is a perspective view of the device of Fig. 1 when closed. This device is shown in Fig. 4 in cross-section taken along the AA plane, which also shows cassettes 103, 104 and 105 (Fig. 1).

The same cassettes are also shown in Fig. 5, which is a rotated view of the cross-section of Fig. 4. The cassettes are also shown in Fig. 6, with the outer shell partially removed.

Fig. 7 (A and B) illustrate an embodiment in which cassettes are fixed to the external shell of the module with bolts. In Fig. 7A, bolts 705 and 705’ fasten cassette 105, bolts 704 and 704’ cassette 104, and bolts 703 and 703’ cassette 103. Corresponding bolts exist on the parallel wall (not shown). The cassettes and their relative position are also shown in Fig. 7B, in which all walls have been removed.

Fig. 7C further illustrates how cassette 105 is fixed to metal shell 701 by metal holder 702 which is itself fixed to metal shell 701 with bolts 706. Cassette 105, in turn, is fixed to holder 702 with nonmetal bolts and nuts 707. Nonmetal parts are convenient to use inasmuch as they avoid the creation of dangerous fragments during the explosion.

Fig. 7D further illustrates holders 707 and 708 used to fix a cassette 709 to the device of the invention by bolts (one of which, 710, is shown). In this embodiment, the cassette is assembled from nonmetal layers 711, 712, 713 and 714. Said layers can be made of different materials and may have different thickness. Between these layers there is placed explosive 41188/20 material 715 that is separated by separators 716, which can be metallic or nonmetallic. All this assemble is fixed together with bolts and nuts 717, which in this particular embodiment are nonmetallic, but may be metallic as well.

Cassettes 103-105 are different from what is known in the art, in that they are made of layers of lightweight, fragile material, such as glass or polymeric material, within which reactive material is housed. Specific illustrative examples of suitable materials are glass, glass-ceramic, ceramic and polymeric layers. The following exemplify suitable materials for the cassettes: Glass Materials Soda-lime silicate Borosilicate Alkali-Aluminosilicate Quartz, silica Lead-Barium Glass-ceramic Materials Beta-Quartz solid solution glass-ceramic Beta-Spodumene solid solution glass-ceramic Ceramics Spinel Sapphire Alon Bulk Polymers Polycarbonate (PC) Polymethyl-methacrylate (PMMA) Polyurea Polyurethane Polyethylene-terephthalate (PE) Soft Polymers Polyvinyl-Butyral (PVB) Thermoplastic Polyurethane (TPU) Ethylene-Vinyl Acetate (EVA) Ionomer-based It should be noted that all the materials mentioned above could be both transparent or opaque.41188/20 A variety of reactive materials can be used in conjunction with the device of the invention, as well known to skilled persons. Illustrative examples of suitable reactive materials include C4, LF2 (such as that manufactured by Ensign-Bickford Aerospace & Defense - https://www.ebad.com/wp-content/uploads/2019/09/LF-2-released-5-12-20.pdf), and low- burning rate explosive (LBR). A typical (but not limiting) thickness of the reactive material is in the range of 1-10 mm.

According to the invention, once the cassettes are in place, the empty volume of hollow body 101 is filled with a polymeric foam, such as, for example, one selected from among polyurethane, expanded polystyrene (EPS), extruded polystyrene (XPS), preformed polyisocyanurate, and spray polyurethane (SPF).

This is seen in Fig. 8, which is a photograph of an actual device according to one embodiment of the invention. The assembling process of the device of the invention can be made in different stages, so long as the polymeric foam fills essentially all voids therein. Fig. 9 shows two stages of the assembling of the device of Fig. 8. In Fig. 9A foam 800 is applied to surfaces of the hollow body 101, to fill spaces that are not easily reached after the reactive cassettes are put in place. Then, the cassettes are connected to body 101, above the previously applied foam, as seen in Fig. 9B.

Lastly, the remaining void space is completely filled with polymeric foam, to yield the filled device of Fig. 8.

Fig. 10 is a photograph of an actual assembled cassette 1001, according to one embodiment of the invention.41188/20 Nonmetal material 1002 is assembled with an explosive material layer 1003 by nonmetal bolts and nonmetal nuts 1004. Separative constructive parts 1005 could be made both from metal and nonmetal materials. This part improves reactive armor performance.

Layer 1002 of cassette 1001 is made of a fragile material, such as glass or polymeric material.

A bottom layer, which can be made of the same or different material is provided (shown in this figure as made of the same material 1002) between which the reactive material is sandwiched.

Example The device of Fig. 11 (also referred to herein as "cassette") was closed with a plate before being subject to attack by a threat.

Fig. 12A shows 5 cassettes that were installed at the testing rig where the 3 middle cassettes had explosive, and the two ate the far sides were inert ones. An anti-tank rocket was applied at middle cassette (third from the edge). Fig. 12B shows the result of the attack. The middle cassette was destroyed, while all other cassettes survived the explosion. This illustrates the advantages of the invention of providing low collateral damage. of the explosive of the remaining cassettes was not activated, and the cassettes kept their structural integrity and defense functionality. As seen in the photograph of Fig. 11, beside an expected deformation of the lid 1101 of the device, the foam absorbed the fragments of the cassette and remained otherwise intact, as seen in the portion 1102 of lid 1101 that was removed.

As will be apparent to the skilled person, the device of the invention achieves two important results: it provides effective protection against threats at relatively low cost, since the absorptive material is a low-cost, commercially available polymeric foam, and does so while maintaining a low weight. Moreover, the effect of the foam on the fragments of the actuated 41188/20 reactive cassette is such that they are contained within the device, thus avoiding damage to the surroundings.

All the above description of embodiments of the invention have been provided for the purpose of illustration and are not meant to limit the invention in any way. As will be apparent to the skilled person, devices of the invention can be provided in different sizes and shapes, comprising different numbers of compartments and reactive elements, all without exceeding the scope of the invention.

Claims (6)

41188/20 8 2 03 8 / 2 - 9 - Claims

1. A reactive armor for defeating threats, comprising one or more fragile reactive plates contained in an outer housing, the void space of said housing being filled with a polymeric foam, wherein the one or more fragile reactive plates consist of reactive material sandwiched between two fragile layers.

2. The reactive armor of claim 1, wherein the fragile material is selected from among glass, glass-ceramic, ceramic, or their combinations.

3. The reactive armor of claim 1, wherein the polymer is selected from among polyurethane, expanded polystyrene (EPS), extruded polystyrene (XPS), preformed polyisocyanurate, and spray polyurethane (SPF).

4. The reactive armor of claim 1, wherein the reactive material is selected from among C4, LF2, and LBR.

5. The reactive armor of claim 1, wherein the various parts are fixed using non-metallic fastening elements.

6. The reactive armor of claim 7, wherein the fastening elements comprise nuts and bolts.