Patent Grant
8220378
This invention relates, in general, to military-grade armor panels and methods of manufacturing the same and, in particular, to military-grade composite armor panels that provide for blast and fragment protection from explosive devices as well as ballistic mitigation.
In response to ever-increasing anti-armor threats, improvements are warranted in the field of blast and fragment protection from explosive devices as well as ballistic mitigation. In particular, OEM and retrofit armor panels are needed that meet or exceed the protection provided by existing armor panels such as 0.202″ High Hard Steel (HHS) panels and ⅜″ Rolled Homogeneous Armor (RHA) panels.
A composite armor panel and method of manufacturing the same are disclosed that provide blast and fragment protection from explosive devices as well as ballistic mitigation. In one embodiment, a plurality of ceramic spheres are positioned in contact with an armor substrate. A polymer layer, which may include a polyurea, polyurethane, or hybrid thereof, for example, is interposed between the plurality of ceramic spheres such that the polymer layer partially or fully encapsulates the plurality of ceramic spheres and bonds the plurality of ceramic spheres to the armor substrate. Depending on the application of the polymer layer, the plurality of ceramic spheres are either partially exposed or completely encapsulated and, in both instances, oriented in a direction of anticipated impact.
For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:
While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.
Referring initially to
As illustrated, the Humvee 10 is outfitted as a troop carrier that is extremely effective in difficult terrain regardless of road type or weather conditions. In this configuration, the Humvee 10 is designed to protect the lives of the soldiers being transported as well as the integrity of any onboard cargo. A body tub 12, a bed 14, a rear fender 16, a front hood 18, and a roof 32 are manufactured from aluminum panels which are appropriately bonded and riveted together. Steel components such as a windshield 20 and front grill 22 add further armor and protection. A V8, 6.2 liter displacement, fuel injection engine transfers power to drive axles and onto rear tires 24 and 26 and front tires 28 and 30 which include a runflat system to enable operation even with one or more flat tires.
For additional protection, doors 34 and 36 comprise composite armor panels that provide blast and fragment protection from explosive devices as well as ballistic mitigation. As will be explained in additional detail hereinbelow, the composite armor panels include a substrate having a polymer layer disposed thereon. Ceramic spheres are secured to the substrate by the polymer layer and may or may not be in contact with the substrate. Moreover, the polymer layer may or may not completely encapsulate the ceramic spheres. For additional protection, an armor plate may be integrated into the composite armor panel and positioned in an opposing relationship to the armor substrate by the polymer layer. The composite armor panels described herein impart protection that meets or exceeds that of existing armor panels.
It should be appreciated that although the composite armor panels are described as being utilized in the doors of a Humvee, the composite armor panels described herein may be utilized with other types of vehicles and structures. By way of example, the composite armor panel may form a portion of a tank or a wall of a structure, regardless of whether the structure is permanent or fixed. By way of further example, the composite armor panel may form a portion of a non-military vehicle such as a fuel vessel of a tanker or hull. Further, as will be described in further detail hereinbelow, the composite armor panels presented herein may be offered as either an OEM product or a retrofit.
Referring jointly to
In one presently preferred exemplary embodiment, the composite armor panel 42 comprises a single layer or array of ceramic spheres 44 and the ceramic spheres 44 are positioned in contact with each other to provide further support. For example, exterior ceramic sphere 48 is contact with four adjacent ceramic spheres and an interior ceramic sphere 56 is in contact with six adjacent ceramic spheres. In this arrangement, the ceramic spheres are positioned in repeating A and B rows wherein the A row is shifted with respect to the B row by approximately ½ the diameter of a ceramic sphere.
The layer of ceramic spheres 44 is oriented in the direction of anticipated impact as represented by arrow 58. In operation, as will be explained in further detail hereinbelow, the layer of ceramic spheres 44 and the polymer layer 50 act in concert to asymmetrically deform the shape of the of the impacting projectile or fragment and absorb and dissipate the kinetic energy of the deformed impactant, thereby arresting the impactant and maintaining the safety and integrity of the troops and/or cargo being transported.
In
More preferably, the polymer is a polyurea. By way of example, polyurea elastomers may be derived from the reaction product of an isocyanate (A-side) component and an isocyanate-reactive or resin blend (B-side) component. In another embodiment, the polyurea elastomers may be derived from hybridized isocyanate/resin components. The isocyanate may be aromatic or aliphatic in nature. Additionally, the isocyanate may be a monomer, a polymer, or any variant reaction of isocyanates, quasi-prepolymer or a prepolymer. The prepolymer, or quasi-prepolymer, may comprise an amine-terminated polymer resin, or a hydroxyl terminated polymer resin.
More specifically, the resin blend utilized with the prepolymer or quasi-prepolymer may comprise amine-terminated polymer resins, and/or terminated chain extenders. The resin blend may also contain additives, or non-primary components. For example, the additives may serve cosmetic functions, weight reduction functions, or provide fire-retardant characteristics. By way of further example, these additives may contain hydroxyls, such as pre-dispersed pigments in a polyol carrier.
By way of another example, a polyurethane/polyurea hybrid elastomer may be utilized which is the reaction product of an isocyanate component and a resin blend component. The isocyanate may be aromatic or aliphatic in nature. Further, the isocyanate may be a monomer, a polymer, or any variant reaction of isocyanates, quasi-prepolymers or prepolymers. The prepolymer, or quasi-prepolymer, may comprise an amine-terminated polymer resin, or a hydroxyl-terminated polymer resin. Additionally, the resin blend may comprise blends of amine-terminated and/or hydroxyl-terminated polymer resins, and/or amine-terminated and/or hydroxyl-terminated chain extenders. In one embodiment, the resin blend contains blends of amine-terminated and hydroxyl-terminated moieties. The resin blend may also contain additives, non-primary components or catalysts.
By way of a further example, a polyurethane elastomer may be utilized that is the reaction product of an isocyanate component and a resin blend component. In another embodiment, the polyurethane elastomer is the reaction product of hybridized isocyanate/resins. The isocyanate component may be aromatic or aliphatic in nature. Further, the isocyanate component may be a monomer, polymer, or any variant reaction of isocyanates, quasi-prepolymer, or a prepolymer. The prepolymer, or quasi-prepolymer, may comprise hydroxyl-terminated polymer resins. The resin blend may be made up of hydroxyl-terminated polymer resins, being diol, triol or multi-hydroxyl polyols, and/or aromatic or aliphatic hydroxyl-terminated chain extenders. The resin blend may also contain additives, non-primary components, or catalysts.
Returning to the description of
Similarly, a chamber 88 holds an isocyanate-reactive component 90 and a mixing element 92 agitates the isocyanate-reactive component 92. A flowline 94 connects the chamber 88 to the proportioner 76 which, in turn, is connected to a heated flowline 98 having a heater 100. The heated isocyanate-reactive component 90 is provided to the mix head 82 where the polyisocyanate prepolymer component 70 and the isocyanate-reactive component 90 are sprayed as a mixed formulation 102 onto the armor substrate 62. The formulation 102 then begins to cure as the polymer layer 64.
Typically, pressures between about 1,000 psi and about 3,000 psi and temperatures in a range of about 145° F. to about 190° F. (about 63° C. to about 88° C.) are utilized to impingement mix the two components. In other implementations, however, the temperature may be as low as room temperature. Suitable equipment includes GUSMER® H-2000, GUSMER® H-3500, and GUSMER® H-20/35 type proportioning units fitted with either a GUSMER® GX-7, a GUSMER® GX-7 400 series, or a GUSMER® GX-8 impingement mix spray gun (all equipment available from Graco-Gusmer of Lakewood, N.J.). It should be appreciated, however, that the use of plural component spray equipment is not critical to the present invention and is included only as one example of a suitable method for coating the armor substrate. By way of another example, compression molding or injection molding processes, such as reaction injection molding (RIM) processes, may be utilized to manufacture the composite armor panel.
In
Suitable ceramic materials include those having aluminum oxide (alumina or Al2O3), boron carbide (B4C), boron nitride (BN), silicon carbide (SiC), silicon nitride (Si3N4), and zirconium oxide (zirconia or ZrO2), for example. Preferably, the ceramic spheres 104 are at least 90% alumina. Regardless of the ceramic material selected, a high hardness is preferable. A Vickers Hardness number of at least 15 is suitable and a Vickers Hardness number of at least 30 is more suitable.
In
In
In
As previously discussed, the composite armor panel taught herein includes a substrate having a layer of ceramic spheres bonded thereto by a polymer layer. The ceramic spheres may or may not be in contact with the substrate. Moreover, the polymer layer may or may not completely encapsulate the ceramic spheres. Additionally, an armor plate may be positioned in an opposing relationship with the armor substrate to add further protection. Also, as previously discussed, the composite armor panels may be OEM offerings or retrofit panels that are bolted or otherwise secured to a preexisting surface. The following four figures,
The present invention will now be illustrated by reference to the following non-limiting working examples wherein procedures and materials are solely representative of those which can be employed, and are not exhaustive of those available and operative.
A 0.202″ HHS armor substrate was selected and polyurea/polyurethane plural component coating (by way of example, such coatings are available from Speciality Products, Inc. of Lakewood, Wash.) was applied at a thickness of approximately 0.5″ with GUSMER® spray equipment (available from Graco-Gusmer of Lakewood, N.J.). Prior to the coating curing, 1″ diameter alumina spheres were potted in the polymer in contact with the 0.202″ HHS armor substrate. The composite armor panel was then permitted to complete curing.
The composite armor panels of Examples 2-11 were prepared substantially according to the procedures presented in Example I with the components noted in Table II. For purposes of comparison, the components of Example 1 are also presented in Table I.
V-50 Ballistic Limit Testing Methodology. Velocity-50% or V-50 ballistic limit testing is a statistical test developed by the United States Department of Defense that is often used as a design tool by manufacturers during the development and assessment of new armor designs. The V-50 test identifies the theoretical velocity at which a specific projectile has a 50% probability of either penetrating or being stopped by an Armor Under Test (AUT). To compute the velocity, testers fire enough projectiles at the AUT at various velocities to obtain equal groups of non-penetrating and penetrating impacts within a predetermined velocity range which is typically less than 50 feet/second. The V-50 ballistic limit is calculated as the average velocity of the projectiles. Thus, the V-50 covers the identification, within statistical reason, of the velocity at which the AUT stops the projectile 50% of the time.
Table II depicts the V-50 test results for various AUTs using 20 mm 830 grain FSP rounds fired at approximately 50 meters from a smooth bore Mann barrel while varying the striking velocity.
Ballistic Penetration Testing Methodology. Ballistic penetration testing is a pass/fail test that is used as a design tool by manufacturers during the development and assessment of new armor designs. The ballistic penetration test assesses AUTs under sustained, high-speed, large-caliber fire.
Table III depicts the ballistic penetration results for various AUTs using 7.62 mm rounds fired from a Pulemyot Kalashnikov (PK) general-purpose, gas-operated, belt-fed, sustained fire machine gun. Four shots with less than a 4″ spread were fired at 50 meters into the AUTs and ballistic penetration results were noted.
The V-50 ballistic limit and ballistic penetration testing methodologies and results presented above demonstrate that the composite armor panel presented herein provides blast attenuation from fragments and ballistic mitigation from high-speed, high-caliber firearms. The protection afforded by the composite armor panel exceeds the protection provided by ⅜″ RHA as presented in the Department of Defense Specification MIL-A-12560 which discusses armor plate, steel, wrought, homogeneous materials for use in combat-vehicles and for ammunition testing. The composite armor panels described herein provide this level of protection without the weight and encumbrance associated with ⅜″ RHA.
Further, based on the V-50 ballistic limit and ballistic penetration testing methodologies and results, ballistic resistance performance increases as the size of the ceramic sphere increases. Additionally, the highest performing substrate was the 0.202″ HHS.
While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.
The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Contract No. N41756-04-M-4238 awarded by the Department of the Navy.
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