Patent Application
20100294123
The present disclosure relates to an armor system that resists penetration by projectiles.
Conventional armor may be subjected to a variety of projectiles designed to defeat the armor by either penetrating the armor with a solid or jet-like object or by inducing shock waves in the armor that are reflected in a manner to cause spalling of the armor such that an opening is formed and the penetrator (usually stuck to a portion of the armor) passes through the armor, or an inner layer of the armor spalls and is projected at high velocity without physical penetration of the armor.
Some anti-armor weapons are propelled to the outer surface of the armor where a shaped charge is exploded to form a generally linear “jet” of metal that will penetrate solid armor. Such weapons are often called Hollow Charge (“HC”) weapons. A rocket propelled grenade (“RPG”) is such a weapon. An RPG 7 is a Russian origin weapon that produces a penetrating metal jet, the tip of which hits the target at about 8000 m/s. When encountering jets at such velocities, solid metal armors behave more like liquids than solids. Irrespective of their strength, they are displaced radially and the jet penetrates the armor.
Various protection systems are effective at defeating HC jets. Amongst different systems, the best known are reactive armors that use explosives in the protection layers that detonate on being hit to break up most of the HC jet before it penetrates the target. Such systems are often augmented by what is termed “slat armor,” a plurality of metal slats disposed outside the body of the vehicle to prevent the firing circuit of an RPG from functioning.
A second type of anti-armor weapon uses a linear, heavy metal penetrator projected at a high velocity to penetrate the armor. This type of weapon is referred to as EFP (explosive formed projectile) or SFF (self forming fragment), sometimes referred to as a “pie charge” or a “plate charge.
In some of these weapons the warhead behaves as a hybrid of the HC and the EFP and produces a series of metal penetrators projected in line towards the target. Such a weapon will be referred to herein as a Hybrid warhead. Hybrid warheads behave according to how much “jetting” or HC effect the hybrid warhead has, and up to how much of a single, large penetrator-like EFP it produces.
Another type of anti-armor weapon propels a relatively large, heavy, generally ball-shaped solid projectile (or a series of multiple projectiles) at high velocity. When the ball-shaped metal projectile(s) hits the armor, the impact induces shock waves that reflect in a manner such that a plug-like portion of the armor is sheared from the surrounding material and is projected along the path of the metal projectile(s), with the metal projectile(s) attached thereto. Such an occurrence can, obviously, have very significant detrimental effects on the systems and personnel within a vehicle having its armor defeated in such a manner.
While the HC type weapons involve design features and materials that dictate they be manufactured by an entity having technical expertise, the latter type of weapons (EFP and Hybrid) can be constructed from materials readily available in a combat area. For that reason, and the fact that such weapons are effective, these weapons have proven troublesome to vehicles using conventional armor.
The penetration performance for the three mentioned types of warheads is normally described as the ability to penetrate a solid amount of RHA (Rolled Homogeneous Armor) steel armor. Performances typical for the weapon types are: HC warheads may penetrate 1 to 3 ft thickness of RHA; EFP warheads may penetrate 1 to 6 inches of RHA; and Hybrids warheads may penetrate 2 to 12 inches thick RHA. These estimates are based on the warheads weighing less than 15 lbs and being fired at their best respective optimum stand off distances. The diameter of the holes made through the first inch of RHA would be: HC up to an inch diameter hole; EFP up to a 9 inch diameter hole; and Hybrids somewhere in between. The best respective optimum stand off distances for the different charges are: an HC charge is good under 3 feet, but at 10 ft or more it is very poor; for an EFP charge a stand off distance up to 30 feet produces almost the same (good) penetration and will only fall off significantly at very large distances such as 50 yards; and for Hybrid charges penetration is good at standoff distances up to 10 ft, but after 20 feet penetration falls off significantly. The way these charges are used is determined by these standoff distances and the manner in which their effectiveness is optimized (e.g., the angles of the trajectory of the penetrator to the armor). These factors affect the design of the protection armor.
While any anti-armor projectile can be defeated by armor of sufficient strength and thickness, extra armor thickness is heavy and expensive, adds weight to the armored vehicle using it, which, in turn, places greater strain on the vehicle engine and drive train, and thus has a low “mass efficiency.”
Armor solutions that offer a weight advantage against these types of weapons can be measured in how much weight of RHA it saves when compared with the RHA needed to stop a particular weapon penetrating. This advantage can be calculated as a protection ratio, the ratio being equal to the weight of RHA required to stop the weapon penetrating, divided by the weight of the proposed armor system that will stop the same weapon. Such weights are calculated per unit frontal area presented in the direction of the anticipated trajectory of the weapon.
Thus, there exists a need for an armor that can defeat the high energy projectiles (i.e., projectiles having velocities of greater than about 2500 m/s) from anti-armor devices without requiring excess thicknesses of armor, and thus have a high mass efficiency. Such armor may be made of materials that can be readily fabricated and incorporated into a vehicle design at a reasonable cost, and may be added to existing vehicles.
The present disclosure is directed to overcoming shortcomings and/or other deficiencies in existing technology.
In accordance with one aspect, the present disclosure is directed toward an armor system for protecting a vehicle from a projectile, the projectile having an expected trajectory and the vehicle having a hull. The armor system includes a modular armor subsystem configured to be mounted exterior to the vehicle hull. The modular armor subsystem includes a leading layer having metal, leading relative to the expected projectile trajectory, and an intermediate sheet-like layer having low density material, of a density less than metal, abutting a rear surface of the leading layer. The armor system also includes an intermediate sheet-like layer having glass fiber material and abutting a rear surface of the intermediate low density material layer, and an intermediate sheet-like layer having metal and abutting a rear surface of the intermediate glass fiber layer.
According to another aspect, the present disclosure is directed toward an armor system for protecting a vehicle from a projectile, the projectile having an expected trajectory and the vehicle having a hull. The armor system includes a modular armor subsystem configured to be mounted exterior to the vehicle hull. The modular armor subsystem includes a leading layer, relative to the expected projectile trajectory and having metal, and an intermediate sheet-like layer having low density material, of a density less than metal, abutting a rear surface of the leading layer. The modular armor subsystem also includes an intermediate sheet-like layer having glass fiber material and abutting a rear surface of the intermediate low density material layer, and a first intermediate sheet-like layer having metal and abutting a rear surface of the intermediate glass fiber layer. The modular armor subsystem further includes a second intermediate sheet-like layer having metal and abutting a rear surface of the first intermediate metal layer.
Armor system 10 may include an exterior armor subsystem 16 and an interior armor subsystem 18. Exterior armor subsystem 16 may include a leading sheet-like layer 20 having metal. Exterior armor subsystem 16 may also include an intermediate sheet-like layer 22 having material of a density that is lower than metal, where a front surface 22a of layer 22 may abut a rear surface 20a of layer 20. Exterior armor subsystem 16 may further include an intermediate sheet-like layer 24 having glass fiber material, where a front surface 24a of layer 24 may abut a rear surface 22b of layer 22. Exterior armor subsystem 16 may also include an intermediate sheet-like layer 26 having metal, where a front surface 26a of layer 26 may abut a rear surface 24b of layer 24. Exterior armor subsystem 16 may further include an intermediate sheet-like layer 28 having metal, where a front surface 28a of layer 28 may abut a rear surface 26b of layer 26. A dispersion space 30 may be disposed between a rear surface 28b of layer 28 and a front surface 14a of vehicle hull 14.
Leading layer 20 may include a metal such as, for example, a high strength aluminum alloy having a tensile strength greater than 20,000 lbs./in.2 and an elongation to break greater than 10%. Therefore, layer 20 may have a relatively high elongation at tensile rupture. Layer 20 may include high strength aluminum alloys such as, for example, 7039 aluminum, 5083 aluminum, 6061 aluminum, and 2024 aluminum. It is also contemplated that layer 20 may include one or more of materials such as, for example, high strength aluminum, copper, steel, stainless steel, magnesium, molybdenum, copper, zirconium, titanium, and nickel. Layer 20 may have a thickness, for example, of between about ⅛″ and about ¾″.
Intermediate layer 22 may include a low density material having a density lower than metal such as, for example, a low density polypropylene composite material. For example, layer 22 may include Tegris®, available from Milliken & Company, 920 Milliken Road, P.O. Box 1926, Spartansburg, S.C. 29303 USA. It is also contemplated that layer 20 may include materials selected from one or more low density materials such as, for example, Kevlar® reinforced polymer or plastics, polyethylene composites, and hybrid materials formed from one of these alternative low density materials. For example, layer 22 may be Dyneema®, available from DSM. One skilled in the art given the present disclosure may be able to search out and select other low density materials having similar properties to these exemplary materials. These exemplary materials have been found to help attenuate the high velocity jets of metals that may accompany high energy projectiles, and thus increase the chance of defeating such threats. Layer 22 may have a thickness, for example, of between about 8″ and about 14″.
Intermediate layer 24 may include a glass fiber material such as, for example, R-Glass composite in phenolic resin, for example ShieldStrand™ that may be obtained from OCV™ Reinforcements. For example, layer 24 may include Quicksilver™, available from AGY. It is also contemplated that layer 24 may include an S-Glass material such as, for example, S-2™ and Featherlight™, available from AGY. It is further contemplated that layer 24 may include an E-Glass composite material. It is further contemplated that layer 24 may include composite materials such as, for example, a Kevlar® reinforced polymer material that may be infused with phenolic resin, a Kevlar® woven blanket material including a plurality of plies that may be woven together, or a polyethylene composite material. It is also contemplated that layer 24 may include a carbon fiber woven blanket material. Layer 24 may have a thickness, for example, of between about ½″ and about 4″. It is also contemplated that layer 24 may include any hybrid composite of the above systems.
Intermediate layers 26 and 28 may include similar materials as leading layer 20. Each of layers 26 and 28 may have a thickness, for example, of between about ½″ and about 2″.
Dispersion space 30 may be a space between rear surface 28b of layer 28 and front surface 14a of vehicle hull 14, and may be measured in a direction generally perpendicular to parallel-aligned layer 28 and hull 14. Layer 28 may be spaced from hull 14, for example, by mechanical spacers and/or a low density foam-like material. Accordingly, dispersion space 30 may be a substantially empty space maintained via mechanical spacers, or may be substantially filled with foam-like material. It is also contemplated that both mechanical spacers and foam-like material may be disposed within dispersion space 30. The foam-like material may be any suitable foam material such as, for example, material meeting the FMVSS 302 Burn Rate Test such as EL Foam P300.
Dispersion space 30 may serve to allow significant lateral dispersion of projectile material passing therethrough, thereby impeding the penetration of the projectile material through armor system 10 in the direction of trajectory 12, and may contain a portion of the projectile material within dispersion space 30. The term “lateral” indicates a direction at an angle from the initial line of flight of the projectile (i.e. trajectory 12). As the moving material of the projectile is increasingly dispersed within dispersion space 30, the energy that the projectile exerts incident to the next successive layer (e.g., hull 14) becomes increasingly less concentrated. In addition, as the thickness of the dispersion space increases, the kinetic energy per surface area that is imparted on the successive layer (e.g., hull 14) decreases. Dispersion space 30 may have a width, for example, of between about ½″ and about 2″, allowing dispersion space 30 to dissipate significant amounts of kinetic energy, without resulting in an impractical overall thickness of armor system 10.
Vehicle hull 14 may include a high strength steel such as, for example, a 500 Brinell hardness steel. For example, hull 14 may include Mil A-46100 Armor Plate. Hull 14 may have a thickness, for example, of between about ¼″ and about ¾″.
Interior armor subsystem 18 may include an intermediate sheet-like layer 32 having polymer material. A dispersion space 34 may be disposed between a rear surface 14b of hull 14 and a front surface 32a of layer 32. A vehicle interior 36 may be enclosed by a rear surface 32b of layer 32.
Dispersion space 34 may be a space between rear surface 14b of hull 14 and front surface 32a of layer 32, and may be similar to dispersion space 30. Dispersion space 30 may have a width, for example, of between about ½″ and about 2″.
Layer 32 may include a polymer material such as, for example, a polyethylene composite material. It is also contemplated that layer 32 may include a Kevlar® reinforced polymer or plastic material available, for example, from LTC. It is also contemplated that layer 32 may include an R-Glass composite in phenolic resin of a type that may be obtained, for example, from OCV™ Reinforcements. For example, layer 32 may include Quicksilver™, available from AGY. It is also contemplated that layer 32 may include an S-Glass material such as, for example, S-2™ and Featherlight™, available from AGY. It is further contemplated that layer 32 may also include an E-Glass composite material. It is further contemplated that layer 32 may include a composite material such as, for example, a Kevlar® reinforced polymer that may be infused with phenolic resin or a Kevlar® woven blanket material including a plurality of plies that may be woven together. Layer 32 may have a thickness, for example, of between about ½″ and about 2″.
Armor system 10 of
Referring back to
As shown in
Leading layer 120 may have a thickness, for example, of between about ⅛″ and about ¾″, and intermediate layer 122 may have a thickness, for example, of between about 4″ and about 10″. Intermediate layer 124 may have a thickness, for example, of between about ½″ and about 4″. Intermediate layers 126 and 128 may each have a thickness, for example, of between about ½″ and about 2″. Dispersion space 130 may have a width, for example, of between about ½″ and 2″.
Interior armor subsystem 118 may include an intermediate sheet-like layer 132 having synthetic fiber material. A front surface 132a of layer 132 may abut a rear surface 114b of vehicle hull 114. An adhesive having relatively high strength and relatively high elongation to break such as, for example, methacrylate adhesive may be applied to surfaces 114b and/or 132a to attach intermediate layer 132 to hull 114. Hull 114 may have a thickness, for example, of between about ¼″ and about ¾″. A vehicle interior 136 may be enclosed by a rear surface 132b of layer 132.
Layer 132 may include a synthetic fiber material such as, for example, a high strength aramid fiber material. For example, layer 132 may include a high strength aramid fiber material such as, for example, Kevlar®. Layer 132 may function to reduce spalling of components of armor system 100 such as, for example, spalling of vehicle hull 114. It is also contemplated that layer 132 may include an R-Glass composite in phenolic resin of a type that may be obtained, for example, from OCV™ Reinforcements. For example, layer 132 may include Quicksilver™, available from AGY. It is also contemplated that layer 132 may include an S-Glass material such as, for example, S-2™ and Featherlight™, available from AGY. It is further contemplated that layer 132 may also include an E-Glass composite material. It is further contemplated that layer 132 may include a composite material such as, for example, a Kevlar® reinforced polymer that may be infused with phenolic resin or a Kevlar® woven blanket material including a plurality of plies that may be woven together. It is also contemplated that layer 132 may include a polyethylene composite material. Layer 132 may have a thickness, for example, of between about ½″ and about 2″.
Armor system 100, depicted in
Referring back to
As shown in
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed apparatus and method. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed method and apparatus. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
