Patent Application
20100282062
Improvised explosive devices (IEDs) present a significant challenge to conventional armor architectures. One type of IED that has been particularly difficult to defeat is that which produces explosively-formed projectiles (or EFPs). One such EFP device is schematically illustrated in
The EFPs themselves, once formed, typically travel at velocities in the range of 2-4 km/sec. A typical EFP weighing about 500 grams (1 pound) can deliver about 2-3 megajoules (MJ) of energy on impact traveling at about 2.5-3.5 km/sec, concentrated in an area of not more than several square inches. Consequently, such EFPs easily penetrate expedient armor installed on vehicles made from conventional armor materials, including RHA. Therefore, to defeat such threats using conventional materials, the thickness of the armor layers or plates is increased, making the vehicles excessively bulky, heavy and prone to mechanical failures. For example, if an EFP would penetrate 4″ to 5″ thick conventional RHA, then an RHA or steel plate of sufficient thickness to defeat the threat would have a corresponding areal density in the range of 160-200 pounds per square foot. Therefore, a vehicle that needs a protective area of 100 square feet would require steel/RHA armor in excess of 16,000-20,000 lbs., making it practically an impossible solution.
Accordingly, there is a need in the art for an armor architecture that is effective against EFPs and other substantial penetrative threats that concentrate a large amount of force over a small impact area. Such an improved architecture preferably will be effective to both disperse the concentrated impact energy as well as deflect the projectile itself from its initial trajectory. Most preferably, the improved architecture will be effective to continually realign the projectile trajectory, further dissipating its penetrative power.
A hybrid armor architecture adapted to protect a body panel from a high-energy ballistic threat is disclosed. The architecture includes a laminate reactive armor panel, an armor plate disposed behind the laminate reactive armor panel and a flyer plate disposed behind the armor plate. The laminate reactive armor panel has a layer of non-explosively reactive material sandwiched between outer layers of ductile material. The displacement of such a ductile plate or a portion thereof is configured to move toward and impact projectile causing a disturbance in its trajectory. This is usually followed by an armor plate or armor body that bears a significant part of the projectile impact and further destabilize it. Finally a break-away plate or flyer plate or plates are provided close to the body panel so that on impact of a high-energy ballistic destabilized projectile with the flyer plate or the portion thereof, to thereby increase the total area of impact with the body panel relative to the projectile alone.
As will be seen, the disclosed architecture typically includes a three-part system including the laminate reactive panel, armor plate disposed behind the reactive panel and a displacement or ‘flyer’ plate as hereafter described. Since threat severity can vary widely, it is to be understood that each of these parts may include multiple of the described panels or plates; for example, multiple laminate reactive panels, armor plates and/or flyer plates may be incorporated to provide the armor architecture in various embodiments. In exemplary embodiments, the flyer plate has break-away parts that break of from the main body upon impact and redistribute impact force over much greater area of contact. This plate is termed a ‘flyer plate’ herein with the understanding that it flies towards the vehicle to expand the area of impact with the vehicle body, as will become apparent in the following description.
A hybrid armor architecture adapted to protect a body panel from a high-energy ballistic threat is further disclosed. The architecture includes a plurality of laminate reactive armor panels, each panel having a layer of non-explosively reactive material sandwiched between outer layers of ductile material, wherein the laminate reactive armor panels are spaced from one another a distance of 0.125 to 0.5 inch. An armor plate having a thickness of 0.1 to 0.75 inch disposed 0.5 to 1 inch is disposed behind the laminate reactive armor panel that is to be positioned nearest the body panel in use. A flyer plate having a thickness of 0.1 to 0.75 inches is disposed 4 to 8 inches behind the armor plate. The flyer plate or a portion thereof is configured to move toward and impact the body panel on impact of a high-energy ballistic projectile with the flyer plate or the portion thereof, to thereby increase the total area of impact with the body panel relative to the projectile alone.
The number of each type of panel/plate in each part of the architecture, their dimensions and material composition are dependent upon the severity of the threat. For highly energetic threats, it may be necessary or desirable to deploy additional numbers of panels/plates in each part of the architecture or in only some part of the architecture. Alternatively, depending on the threat level, the hybrid armor architecture can comprise a laminate reactive armor panel and at least one component selected from either an armor plate disposed behind the laminate reactive armor panel or a flyer plate disposed behind the laminate reactive armor panel. Nonetheless the embodiments described herein can provide significant weight savings relative to an comparable amount of RHA or other similar steel armor solutions.
Aspects of the invention will be appreciated by the person having ordinary skill in the art based on the following description with reference to the following drawings, which are provided by way of illustration and not limitation. The drawings are schematic or cartoon in nature, and are not drawn to scale. No dimensions are implied or should be inferred from the appended drawings, in which:
Herein, when a range such as 5-25 (or 5 to 25) is given, this means preferably at least 5 and, separately and independently, preferably not more than 25.
The armor architectures disclosed herein are designed to defeat projectiles, such as an EFP, an RPG (rocket propelled grenade) or a 0.50 Cal M2 round, through a combination of cumulative effects that both destabilize and deflect an incoming projectile, as well as disperse and consume substantial proportions of the projectile's energy. The armor architectures described herein achieve these effects prior to the projectile impacting the skin of a vehicle or other similar structure that the armor is employed to protect. Because much of the projectile's penetrative force is dissipated or consumed by the armor architecture prior to impacting the vehicle (or other contrivance) body, it is rendered incapable to penetrate that body before impacting it.
An exemplary embodiment of improved armor includes a hybrid architecture that combines non-explosive reactive and passive armor components as will be further described. Such an embodiment is illustrated schematically in
The laminate reactive-armor panels 12 are described first. The term non-explosive reactive means that the laminate does not contain any explosive or detonating material but it does contain material that can gasify and create pressure on the two adjoining plates and push them apart. As a result these laminates do not pose any safety issues by unintentional setting off of explosives as in the case of explosive reactive armor. Each laminate panel 12 includes at least two outer layers 12a of a ductile material (elongation to failure preferably >5%) and an inner layer 12b made of a non-explosively reactive material sandwiched between the two outer layers 12a. By non-explosively reactive, it is meant that as an EFP contacts and travels through layer 12b, the material of layer 12b is caused to significantly volumetrically expand as the result of either a) expansive vaporization through absorption of thermal energy provided by an EFP and consequent phase-change to a gaseous state, or b) a non-explosive chemical reaction that produces expansive gaseous products. Such volumetric expansion of the material includes a class of reactions called ballotechnic reactions which are essentially pressure induced but non-detonating. If expansion is achieved through a chemical reaction, it is preferred the reaction is exothermic so as to maximize the heat developed and consequent expansion of the resulting gaseous product. The term ‘non-explosive’ in this context means that the material in layer 12b is not an incendiary, pyrophoric or detonating material—it does not mean that the material does not ‘explode’ in the sense that it ‘expands in volume’ or ruptures the outer layers 12a sandwiching it in between. For example, zinc and sulfur can react exothermically to produce zinc sulfide. The resultant temperature rise is sufficient to cause sublimation of zinc sulfide thus giving rise to a high volume of expansive gas. Alternately a mixture of sulfur and petrolatum in the form of paste can be used to produce highly volatile products upon impact. However, this is an endothermic reaction. Therefore selection is not restricted to exothermic reactions. As will be explained shortly, a primary function of the layer 12b is to rupture and expand the outer layers 12a. The material of layer 12b should be stable in general, but effective to react and expand substantially on input of substantial thermal energy as generated by an impacting EFP as described above. A simple calculation can show that rapid conversion of a material like polyethylene into gaseous monomers (extreme impact conditions are expected to unzip the polymer) can generate pressures in excess of 900-1000 atmospheres. For example, a mass of polyethylene having a diameter of 5 cm, which is comparable to the size of holes observed in a typical EFP (described in an example later), and a thickness of about 6 mm could generate a pressure in excess of 970 atmospheres or 13780 psi upon instantaneous gasification from a high energy impact. Such a force would be sufficient to force open the plates 12a and make them move away from each other. These high values are based on the assumption that the temperature of gas remains under standard condition, which is unlikely. So if it is accepted that a temperature rise would occur, then the pressure values given above would increase. Since the temperature of gas is not known, the pressure values given above serve as the least amount of pressure that could be expected from such a gasification event, such as an EFP passing through the material of layer 12b.
The ductile material used for layers 12a can be made from metals such as copper, aluminum, iron, steel, molybdenum, tantalum, magnesium, titanium and/or alloys of these. Alternatively, the layers 12a can be made from non-metallic materials that possess ductility, including fiberglass, fiber-reinforced polymers and elastomers polymers including filled elastomers. Of these, metallic materials are preferred for reasons that will be explained. The non-explosively reactive material for layer 12b can be selected from among a range of materials that either will chemically react to produce expansive gaseous products or themselves be vaporized and caused to expand from thermal energy delivered by the EFP. If the latter, the material for layer 12b should be selected to have a low enthalpy of vaporization (ΔHv) so that it will be more rapidly vaporized and then caused to expand on application of thermal energy from the EFP. Examples of suitable materials for layer 12b include polymers such as polyethylene polymers, gum rubbers, Teflon™ polymers (polytetrafluorethylenes), polyurethanes and copolymers thereof. They also include materials participating in ballotechnic reactions in which intense pressure is required (experienced in EFP events) to initiate chemical reactions. Examples of reactive materials for layer 12b, which produce expansive gaseous products through non-incendiary reactions, include mixtures of zinc and sulfur embedded within incompressible liquids or waxes, propoellants such as aluminum powder mixed with perchlorates, inorganic ammonium salts such as NH4NO3, (NH4)2S, etc., and low-molecular-weight materials prone to sublimation such as elemental sulfur or cakes thereof. In addition, it is possible to combine highly exothermic reactions such as thermite (a mixture of aluminum powder and iron oxide) and easy-to-sublime materials like zinc sulfide, sulfur, low molecular weight polyethylnes, gum rubber, Teflon or PTFE etc.
In a preferred embodiment, the outer layers 12a of the laminate panels 12 are aluminum layers and the material of layer 12b is a polyethylene sheet. Preferably, the outer layers 12a of each panel 12 have the same thickness, preferably 0.05-0.25, preferably 0.08-0.2, preferably 0.1-0.15, preferably 0.125, inch. Layer 12b preferably has a thickness of 0.1-0.5, preferably 0.15-0.4, preferably 0.2-0.3, preferably 0.25, inch. An armor plate 14 is disposed behind the laminate non-explosive reactive armor panels 12 relative to the trajectory of an EFP 4. The armor plate 14 can be a layer of conventional armor material, such as steel RHA. Alternatively, it can be a metal plate such as iron, steel, stainless steel, titanium, or an alloy of these with or without other metals to impart greater strength (for example with molybdenum, tantalum, nickel, copper, etc.), as well as metallic or non-metallic fiber reinforced polymer, metal or ceramic composites, reinforced or monolithic ceramics such as lithium aluminosilicate glass ceramics, strengthened glasses, boron carbides, carbides of silicon, titanium, nitrides of aluminum, silicon, titanium, oxides of aluminum, silicon and mixtures thereof or carbon-based composites. The armor plate 14 is a plate of strong material, which can include metals as described above, which are used in conventional armor plating, alone or in conjunction with other reinforcing materials such as in a laminate with Kevlar, fiberglass mats, fiber-reinforced polymer mats, etc. One alternative material is composed of a ceramic layer that is backed by RHA or other composite materials or combination of armor materials termed as hybrid armor materials in which layers of armor materials are combined to form a highly effective armor plate. The armor plate 14, which in another preferred embodiment is composed of steel RHA, preferably has a thickness of 0.1 to 2, preferably 0.2 to 0.5, preferably 0.3 to 0.4, preferably 0.375, inches. Alternatively, a plurality of armor plates 14 may be provided, each individually having a thickness within the specified ranges, or all of which together having a total thickness within those ranges, depending upon the threat level. It is understood that thickness of lightweight composites may be greater than that of RHA but not necessarily having a greater areal density than RHA.
A flyer plate 16 is disposed behind the armor plate 14, adjacent the body panel 5 or similar structure that is to be protected. A flyer plate 16 can be made from similar materials and have similar thickness as the armor plate 14. The flyer plate 16 preferably has a thickness of 0.1 to 1, preferably 0.1 to 0.75, preferably 0.125 to 0.5, or preferably about 0.375, inches. It is preferable that the flyer plate 16 has a high elongation to failure value of greater than 5, preferably 8, or preferably 10, %. It is preferably that the flyer plate 16 has a high tensile strength of greater than 40,000, preferably 50,000, preferably 60,000, or preferably 70,000, psi. However, unlike the armor plate 14, which is a continuous sheet of material or materials having an order of armor module dimensions, the flyer plate 16 preferably includes a plurality of discrete plate sections 16a that are attached to one another in a coplanar arrangement to form the flyer plate 16. An exemplary embodiment of the flyer plate 16 is shown in plan view in
In addition to the elements described above and their materials of construction, another aspect of the disclosed armor architecture is their arrangement and spacing from one another and from the body panel 5 or similar structure to be protected. The flyer plate 16 is preferably spaced from the body panel 5, located 1-3 inches, preferably about 2 inches therefrom. The armor plate 14 is disposed in front of the flyer plate 16, preferably spaced 4-8 inches, preferably about 6 inches from the flyer plate 16 (or about 8 inches from the body panel 5). A representative spacer 30 is shown in the armor architecture of
The elements of the armor architecture described above perform complementary functions to protect a body panel 5 from an EFP 4 or other high-energy ballistic threat as will now be described. Additional features and embodiments of the armor architecture 10 and the elements thereof will also be described in conjunction with the following discussion.
As an EFP 4 or other high-energy ballistic threat approaches the armor 10, it will first encounter the laminate non-explosive reactive armor panels 12.
In the embodiment shown in
As will be appreciated, the foregoing effects are compounded each time the EFP encounters a new laminate panel 12 of laminate non-explosively reactive armor. With each successive encounter with a laminate panel 12, additional instability is introduced so as to tilt and deflect and/or break-up the EFP from its original trajectory. Therefore, space and weight permitting, it may be desirable to incorporate multiple such layers. In testing, four such layers composed of aluminum outer layers 12a and a polyethylene reactive layer 12b having thicknesses of ⅛ inch and ¼ inch, respectively, have been found to be effective in conjunction with the other components as described more fully below. Additional reactive materials that have been successfully tested to perform well in place of PE include natural, un-vulcanized rubber and sulfur. As already mentioned, the laminate panels 12 can be set at zero degrees (perpendicular) to the incoming penetrator and also can be set at a variety of angles to the incoming penetrator. Testing performed at zero- and thirty-degree angles relative to the incoming penetrator demonstrated success to prevent penetration into the body panel 5 in conjunction with the additional armor elements as hereafter described.
As explained above, each laminate panel 12 is spaced at a select distance from the next. The stiffness of successive panels 12, particularly their respective layers 12a, may be successively increased or decreased to offer increasingly (or decreasingly) compliant structure as the EFP proceeds. This effect may be achieved, e.g., by varying the thickness of the ductile sheets for layers 12a in the direction toward the body panel 5, their composition, or both.
The armor plate 14 is located behind the laminate panels 12, closer to the body panel 5 as described above. In a preferred embodiment, this plate 14 comprises ⅜-inch thick rolled homogeneous armor (RHA) to absorb the energy of the remaining slug of an incoming EFP 4, or other large or fragmented pieces, after it traverses the laminate panels 12, which by now have absorbed or deflected a proportion of its kinetic energy. The armor plate 14 initiates both deformation and tumbling of the projectile or fragments thereof. As the slug or fragments impact and penetrate the armor plate 14, the energy is even more widely dispersed and more easily absorbed by the armor plate 14 as it tears destructively in penetration of the EFP slug. As it tears, it is believed the aggressive “petalling” of the armor plate 14, preferably RHA, further contacts and impedes the EFP slug, causing it to tumble and further slowing the slug as it continues to approach the body panel 5. It is also possible for the semi-molten mass of copper from the EFP 4 to be dispersed to a great extent upon impact with the armor plate or plates, and in the process create a punched-out disk from the armor plate 14. In such a case, the lengths of projectiles or fragments from the EFP are substantially reduced making it easier to defeat them in successive layer or layers.
In a preferred embodiment illustrated in
The final layer of the present embodiment, closest to the body panel 5, is the flyer plate 16, which is preferably a ⅜-inch (0.375 inch) thick steel RHA plate cut to provide 4″×4″ or 6″×6″ square plate sections 16a as described above, with adjacent sections 16a joined discretely to one another at small regions at their corners. By the time the remaining slug from the EFP 4 penetrates the armor plate 14 and contacts the flyer plate 16, a substantial proportion of its kinetic energy has already been absorbed and dissipated by the elements that came before. The remaining slug, therefore, impacts the flyer plate with substantially reduced kinetic energy compared to the original EFP 4. That slug will impact one of the discrete plate sections 16a of the flyer plate. The impacted plate section 16a will, as a result of the force of impact, be broken free from the adjacent sections 16a to which it is attached only at its corners. The broken-off section 16a will then be forced by the force of the remaining slug, against the body panel 5, resulting in an impact with the body panel 5 across a substantially increased surface area compared to that which would occur from the slug alone. The section 16a of the flyer plate 16 prevents the slug or similar fragment of an EFP from coming into contact with the body panel 5 or similar structure to be protected. The flyer plate 16 construction described above has been shown to take the slug remaining from the EFP 4 following the preceding layers and transfer its momentum to a much larger surface area thereby using the mechanical advantage of dissipating the incoming mass and energy to achieve significant reduction of impact force. For example, a slug of 4 in2 hitting a flyer plate of 8″×8″ is capable of an approximately 16-times reduction in impact-force per area once the flyer plate section 16a impacts the body panel 5. As mentioned above, the flyer plate 16 preferably is disposed approximately 2 inches from the body panel 5 to provide a travel time and space for the optimum effect of momentum and energy dissipation to occur prior to impacting the body panel 5.
Optionally, additional layers of reinforced composite or other layers may be disposed in the approximately two inches of space between the flyer plate 16 and the body panel 5. Such additional layers may provide additional protection against penetrating the body panel, but will also add weight to the overall armor architecture.
Against higher-energy EFP threats, additional layers can be added to the architecture specifically to non-explosive reactive armor laminates and armor plate following them.
Against lower-energy EFP threats, additional weight can be removed from the above architecture by reducing the number of laminate panels 12 and/or the thickness of either or both of the armor plate 14 and flyer plate 16. Alternatively, if tearing or minor penetration of the ⅜″ armor vehicle skin is permitted by the certifying authority, the weight of the overall armor architecture 10 can be reduced by 4 to 6 pounds per square foot given current testing, and still protect occupants against the described threat.
In a further alternative embodiment, the laminate panels 12 described above can be replaced with a laminate architecture that employs one or several of a variety of geometric patterns so that an incoming EFP's path is intersected by several surfaces at obliquities other than zero. For example, as seen in
In another exemplary embodiment, the concentric circular tubes 22a and 22b can be replaced with concentric square- or rectangular-shaped tubes 22c and 22d, as shown in
The above-described armor is composed of a hybrid architecture that uses and takes advantage of both reactive armor components (the laminate non-explosive reactive panels 12) and passive armor components (the armor plate 14 and reinforcing layer 17, if present). In addition to these two components, a third novel component is included, the flyer plate 16, which mechanically reduces the impact energy-per-unit-area when the body panel 5 is finally impacted by the EFP 4, or the slug that remains once passing the active and passive components described above. As already described, the flyer plate 16 takes the energy and momentum of that remaining slug and converts it so that instead of impacting the body panel 5 across the remaining (small) cross-sectional area of the slug, it impacts over a much larger (i.e. 16 times or greater) surface area corresponding to the cross-sectional area of the flyer plate section 16a that breaks off and joins the slug to impact the body panel 5. This transfers the remaining kinetic energy and momentum to a larger cross-sectional area, and also lowers the velocity because momentum is conserved when the initial slug now combines with the flyer plate section 16a, which adds substantially to the mass that must be moved by the kinetic energy originally delivered by the slug alone. These effects, when combined with the remaining armor components herein described, have been shown to reliably prevent penetration into an underlying body panel 5 (simulated by ⅜-inch RHA), based on a 460-gram copper EFP propelled by 7.5 lbs of C4 high explosive from a small enclosure at a range of four to eight feet.
Each of the above elements of the disclosed armor architecture 10 can be prepared via known or conventional methods or techniques. Regarding the laminate panels 12, for example the embodiment illustrated in
The flyer plate 16, as described above, is designed to introduce mechanical effects that transfer the momentum and kinetic energy of the remaining slug to a larger mass and greater surface area prior to impacting the body panel 5. The embodiment described above, and illustrated in
In still a further embodiment, the flyer plate 16 can be provided so that the retention structure adjacent one edge of the plate 16 is more easily disrupted or destroyed than adjacent the opposite or other edge. This will have the effect that on impact of the slug, the flyer plate 16 will be more readily broken away at one edge, causing it to swing or hinge relative to the retention structure that remains temporarily intact. This embodiment may have the impact of further attenuating impact energy.
Now referring to
The first module 42 is provided similarly as the second module 52 mentioned above, and is secured to the front face 54a of the second module 52 by suitable hook-type and ball-and-socket type fasteners as illustrated, or other suitable fasteners known or conventional in the art. For example, the fasteners for both the first and second modules 42 and 52 can be, e.g, screw-type fasteners, sliding fasteners that employ a lock-in-place mechanism such as clips or other appropriate structure.
As will be appreciated, this modular construction will have certain advantages. For example, if the first module 42 is damaged by small arms fire that otherwise cannot penetrate the armor plate 14, then only the first module 42 may be replaced leaving the second module 52, which was undamaged, in place. Alternatively, if both modules 42 and 52 are damaged such as by an EFP, then both modules may be removed and replaced on the underlying and substantially un-damaged body panel 5. It will further be appreciated that other plates, elements and other armor components, including those described above, may also be incorporated into the modules 42 and 52 when and where desired depending on the specific threat to be defeated, space- and weight-constraints permitting.
Within each module 42 and 52, the individual elements and layers may be spaced apart from one another by suitable spacers, not shown. Alternatively, other spacing elements may be used. For example, all of the panels may be drilled to provide concentrically-aligned through-bores, through which a bolt is provided to secure each layer in place at the appropriate spacing, for example using nuts threaded onto the long bolts. Selection of particular structure or spacers to achieve the desired spacing is well within the ability of the person of ordinary skill in the art. In certain embodiments, plates and layers disclosed herein may be curved and not truly planar. For example, the armor plate 14 and/or the flyer plate 16 may have a curved surface to further deflect the incoming EFP 4 or remaining slug.
A substantial advantage of the embodiments disclosed herein is that they are capable to defeat a significant EFP threat at significant weight savings compared to conventional armors required to defeat equivalent threats. For example, the architecture described above, weighing approximately 45 pounds per square foot, represents a weight-savings of approximately 68% compared to the equivalent RHA-alone armor that would be required to defeat an equivalent threat (460-gram copper EFP produced from bowl-shaped copper plate of the same weight by detonating 7.5 lbs. of C4 high explosive in a small, closed-end container at a range of four to eight feet).
As will be appreciated from the foregoing description, the present armor architecture in a preferred embodiment includes at least three basic components: A) laminate non-reactive armor panels 12, B) at least one layer of armor plate 14 that can be similar to conventional RHA armor and C) at least one flyer plate 16 that is positioned a distance (preferably 2 inches) from the body panel 5 to be protected to transfer the momentum of any remaining incoming mass to a much broader surface area prior to impacting the body panel 5, which may reduce as much as 16 times the force/momentum per area of impact, which improves survivability of the body panel 5. It is believed certain of the individual components (A), (B) and (C) mentioned above may be capable on their own, or in combinations of only two of them, to stop individual classes of threats. As it will be shown in one of the examples, if component A manages to reduce the kinetic energy of EFP to a sufficient level, then only component C may be sufficient to protect the vehicle. However, it is believed that the combination of all three is necessary reliably defeat the wide variety of threats that battlefield vehicles typically encounter in modern guerrilla warfare, for example the EFPs described above, RPG-style shaped charges as well as ballistic threats including 50-caliber AP and 14.5 AP rounds.
In order to promote a further understanding of the invention, the following examples are provided. These examples are shown by way of illustration and not limitation.
An armor architecture consisting of 7 layers of laminate non-reactive panels 12 each consisting of two ⅛″ aluminum plates (12a) sandwiching a ¼″ LDPE (low density polyethylene sheet) (12b) arranged in a zig-zag manner (shown in
An armor arrangement was constructed as follows: five laminate non-reactive panels 12 were constructed in such a way that each panel 12 consisted of two ⅛″ aluminum plates (Alloy 6061) (12a) with a ¼″ polyethylene sheet (12b) in intimate contact. The panels 12 were spaced approximately ½″ apart and were oriented at roughly an 11-degree angle with respect to the horizontal plane of the following armor plate consisting of a ⅜″ RHA plate (14) and ½″ fiberglass composite (˜70 vol % E-Glass). A gap of about 1.5″ between the RHA plate and the composite. A flyer plate made of ⅜″ RHA was disposed behind the armor plate and spaced at 2″ from the vehicle skin to be protected. The overall area density of this arrangement was about 58 lbs/ft2. The EFP threat was identical to Example 1. Projectile was aimed at zero obliquity with respect to the armor plate and the flyer plate. The vehicle skin consisted of ⅜″RHA plate as an outer layer, 2″ fiberglass composite in the middle and ¼″ RHA plate representing interior of the vehicle. After the test, the outer skin layer was dented but not perforated thus preventing any damage to the interior. Compared to an RHA armor panel alone, the weight savings was about 59%. One advantage of the armor arrangement in Example 2, over that of Example 1, was in the spacing of the armor components. While in Example 1, the armor arrangement exceeded a target depth of 12″, it was less than 12″ in Example 2. This contrast illustrates the relationship between areal density and compactness of the solution and that the armor architecture described herein is versatile enough to allow an armor designer to tailor the solution to a specified set of constraints.
An armor architecture according to Example 2 was constructed except only four panels (12) were used instead of five. As a result, the areal density of this armor arrangement was reduced to about 53 lbs/ft2. The EFP threat was identical to Example 1. After the test, the outer skin of the vehicle was damaged or punctured, the 2″ fiberglass panels showed cracking, and there was no damage to vehicle's interior plate. As compared to an RHA armor panel alone, weight savings was about 62%. As seen in this and the above Examples, there is a relationship between the areal density of the armor architecture and the acceptable level of damage to the vehicle skin.
The armor architecture of Example 2 was tested against a RPG surrogate and 0.50 Cal M2 AP rounds fired at about 2700′/sec. The RPG surrogate was a rock perforator used in oil industry (Owen Oil Tools Model: Raptor SDP-5000-400). This was tested against RHA plate to provide a benchmark. The critical areal density of the RHA plate needed to defeat this perforator was about 325 psf (or slightly greater than 8 inch thick RHA steel). The armor architecture of Example 2 was able to defeat the RPG surrogate completely and the outer vehicle remained totally unaffected. Similar results were obtained when tested against 0.50 Cal M2 AP round. These test show that the armor architecture described herein is capable of defeating multiple types of high-energy threats, such an EFP, a RPG surrogate and a 0.50 Cal M2 round. It is understood that the armor architecture arrangement will differ depending upon the lethality of the threat level.
While the invention has been described with respect to certain exemplary embodiments, it will be appreciated that various modifications can be made thereto by the person having ordinary skill in the art having reviewed the present disclosure, without departing from the spirit and the scope of the invention as set forth in the appended claims.
This application claims the benefit of U.S. provisional applications Ser. Nos. 60/988,468 filed Nov. 16, 2007 and 61/004,853 filed Nov. 30, 2007, the contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60988468 | Nov 2007 | US | |
| 61004853 | Nov 2007 | US |
