This invention relates generally to protective armor panels and more specifically to protective armor panels to absorb projectiles and projectile energy.
Protective armor such as body armor has been used for many years to provide protection from various objects which can cause bodily harm, including projectiles such as bullets, pointed objects such as knives and swords, blasts and shrapnel generated by explosive devices and the like. In the past, protective armor was rigid and heavy while modem armor, such as that fabricated from aramid fibers, for example KEVLAR, is more flexible and lightweight. However, there is often a tradeoff in that armor that is more flexible and lightweight often provides less protection than armor that is rigid and heavy.
Therefore, there is a continuing need for protective armor that is lightweight and versatile but that also provides a high degree of protection.
Protective armor panels comprising a polymer layer having upper and lower faces generally forming a sheet and a plurality of metal strips each having an upper edge, a lower edge and side faces, said side faces being oriented generally traverse to the upper face of said polymer layer and positioned at least partially within the polymer layer, are disclosed.
In one embodiment, a first set of the plurality of metal strips are arranged on edge and parallel to one another with their side faces normal to the upper face of the protective armor panel and a second set of the metal strips are arranged on edge and parallel to one another and positioned interlocked with and transverse to the first set of metal strips with their side faces normal to the upper face of the protective armor. In an alternate embodiment, the protective armor panels contain one or more additional metal grids.
The metal grid of the protective armor panels can be made from various metals, including stainless steel, while the polymer layer can be made from various polymers, including thermoplastic polymers such as polycarbonate.
Functionally, the metal grid of the protective armor panels fragments the incoming bullet or other projectile to be stopped while the polymer layer absorbs and disburses the energy of the resulting fragments so that the fragments do not escape from but rather remain within the polymer layer. Thus, the invention provides protective armor panels with a number of notable advantages, including a high degree of protection and lighter weight than conventional armor panels constructed using metal sheets.
The protective armor panels of the present invention can be used in the construction of various items in which conventional armor panels are used, including vehicles such as cars and trucks, military equipment such as tanks, armored personnel carriers and the like, general purpose vehicles such as jeeps, body armor and structures such as storage sheds and other buildings.
Preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings. These depict particular embodiments of the invention and are not intended to limit the scope of the invention as set forth in the claims. All of the drawings are schematics rather than precise representations and are not drawn to scale.
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Functionally, the metal grid 14 of the protective armor panels 10 fragments the incoming bullet or other projectile to be stopped while the polymer layer 40 absorbs and disburses the energy of the resulting fragments so that the fragments do not escape from but rather remain within the polymer layer. Thus, the protective armor panels 10 of the present invention provide a high degree of protection. Additionally, since the protective armor panels 10 of the present invention are constructed using metal strips embedded in a polymer as opposed to thick metal sheets, they are lighter in weight than conventional armor panels constructed using metal sheets.
Various metals can be used to construct the metal grid 14 used in the protective armor panels 10 of the present invention. Suitable metals include, for example, aluminum alloys, titanium and stainless steel, with stainless steel being preferred. In general, the metal used should have high tensile strength and hardness and is most commonly a “ballistic grade” metal. The individual metal strips used in the metal grid 14 can range from about ¼ inch to about ¼ inch in width and from about 0.035 inch to about 0.090 inch in thickness, while the spacing between parallel metal strips in the first set of metal strips (22, 24, 26 and 28 in the illustrated embodiment) and the second set of metal strips (30, 32, 34 and 36 in the illustrated embodiment) can range from about ⅛ inch to about ½ inch. The width, thickness and spacing of the individual metal strips as well as the length and number of the individual metal strips to be used in the protective armor panel 10 is determined by the size and shape of the protective armor panel 10 to be constructed, the caliber of the bullet or other projectile to be stopped and space and weight constraints. In general, as the caliber of the bullet or other projectile to be stopped increases, the thickness of the protective armor panel 10 increases, as does the thickness of the metal strips used in the metal grid 14. The thickness of the protective armor panel 10 can range from about 0.25 inch to about 1.5 inches. Preferably, the thickness of the protective armor panel 10 ranges from about 0.25 inch to about 0.75 inch.
Various polymers can be used in the polymer layer 40 of the protective armor panels 10 of the present invention. Suitable polymers include, for example, thermoplastic polymers such as polycarbonate (e.g., Lexan®). A preferred polymer is polycarbonate. The polymer used can be opaque, translucent or transparent, depending on the intended application. In general, the polymer used is most commonly a “ballistic grade” material. The length, width, and thickness of the polymer layer 40 is determined by the size and shape of the protective armor panel 10 to be constructed, the caliber of the bullet or other projectile to be stopped and space and weight constraints. In general, as the caliber of the bullet or other projectile to be stopped increases, the thickness of the polymer layer 40 increases.
It should be understood that more than one metal grid 14 can be used in the protective armor panels 10 of the present invention. Preferably, two metal grids are used together. The number of metal grids 14 to be used is determined by the caliber of the bullet or other projectile to be stopped and space and weight constraints. In general, as the caliber of the bullet or other projectile to be stopped decreases, the number of metal grids 14 increases to decrease the size of the resulting apparatures between the stacked grids. Alternatively, when a single metal grid 14 is used (or only a few metal grids are used), this can be accomplished by decreasing the spacing between the metal strips in the metal grid 14. When multiple metal grids 14 are used, they are typically offset from one another to decrease open spaces in the protective armor panel 10 and thereby increase its protective ability. It should be understood that the ability to see through the protective armor panel 10 decreases as the number of metal grids 14 increases. Thus, while visibility through the protective armor panel 10 may be good when a single metal grid 14 is used, visibility through the protective armor panel 10 may be limited when two or more metal grids 14 are used. Additionally, as the thickness of the polymer layer 40 increases, visibility through the protective armor panel 10 also decreases. If desired, multiple protective armor panels 10 can be used for more energy absorption and to provide a greater degree of protection.
Various methods can be used to construct the protective armor panels 10 of the present invention. In one embodiment, the metal grid 14 is first assembled after which the polymer layer 40 is applied to the metal grid 14 using well-know injection molding techniques. In an alternate embodiment, the polymer layer 40 is prepared using well-know injection molding techniques and then machined to create grooves (see discussion of
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It should be understood that the present disclosure is not limited to the embodiments disclosed herein as such embodiments may vary somewhat. It is also to be understood that the terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting in scope and that limitations are only provided by the appended claims and equivalents thereof.
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20120055324 A1 | Mar 2012 | US |