Patent Application
20120186431
This invention relates generally to the field of armor systems and more specifically to light weight armor systems comprising dilatant material to protect against shape charges (e.g., an explosively formed penetrator (EFP)), other explosive devices, hypervelocity impacts and/or ballistic devices.
Improvised Explosive Devices (IEDs) and shape charges such as Explosively Formed Penetrators (EFPs) have accounted for a large number of combat casualties. Lethality of EFPs comes in part from the shape and arrangement of a concave copper cone, called the liner, which transforms into a forceful jet of fluidic metal which easily perforates steel armor. Despite focused efforts on armor development, Mine Resistant Ambush Protected (MRAP) vehicles and other armored vehicles still cannot defend against these threats. More recently, armor solutions such as the FRAG Kit 5 have been used to protect military vehicles such as Humvees. However, these armor solutions typically weigh around 200 lb/ft2. Since nearly all army vehicles are thousands of pounds overweight, even without any additional armor protection solution, most of these approaches have proved impractical.
According to some embodiments, an armor system comprises a plurality of armor layers. The armor system further comprises one or more dilatant material layers located in between two or more armor layers of the plurality of armor layers.
According to some embodiments, the armor system is operable to improve resistance to impact by a shape charge, an explosively formed penetrator (EFP), an improvised explosive device (IED), a ballistic device or a hypervelocity impact. According to some embodiments, the surface area of a shape charge, an explosively formed penetrator (EFP), an improvised explosive device (IED), a ballistic device or a hypervelocity impact may be increased after penetrating through at least a portion of the dilatant material layer. According to some embodiments, the dilatant material layer may be at least 0.25 inches thick.
Certain embodiments of the invention may provide one or more technical advantages. A technical advantage of one embodiment may include the capability to add a tumble to the path of a projectile device. A technical advantage of one embodiment may include the capability to change the trajectory of a projectile device. A technical advantage of one embodiment may include the capability to slow down particles of a projectile. A technical advantage of one embodiment may include the capability to withstand and resist multiple impacts from particles of a projectile device. A technical advantage of one embodiment may also include the capability to increase impact time. A technical advantage of one embodiment may also include the capability to lower the force exerted on one or more armor layers of an armor system. A technical advantage of one embodiment may also include the capability to decrease the overall impact of a projectile. A technical advantage of one embodiment may also include the capability to decrease the shape change ability of a projectile. A technical advantage of one embodiment may also include the capability to increase the surface area of the front of a projectile.
Further technical advantages of particular embodiments of the present disclosure may include an armor system that is lighter weight than conventional armor. A lightweight armor system of the present disclosure may be capable of protecting against a similar threat as a heavier conventional armor system. Yet another technical advantage of one embodiment may be a relatively low cost solution to provide protection against a variety of projectiles and high velocity impacts. In particular, armor systems comprising dilatant material in accordance with the present disclosure may protect against a shape charge such as an EFP, other explosive devices such as IED's, other projectile threats, bullets, ballistic threats and/or forms of hypervelocity impact.
Various embodiments of the invention may include none, some, or all of the above technical advantages. One or more other technical advantages may be readily apparent to one skilled in the art from the figures, descriptions, and claims included herein.
For a more complete understanding of the present invention and its features and advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
It should be understood at the outset that, although example implementations of embodiments of the invention are illustrated below, the present invention may be implemented using any number of techniques, whether currently known or not. The present invention should in no way be limited to the example implementations, drawings, and techniques illustrated below. Additionally, the drawings are not necessarily drawn to scale.
Teachings of certain embodiments recognize that armor systems may be used to provide protection against and/or reduce impact of various projectiles such as but not limited to shaped charges, explosively formed penetrators (EFPs), IEDs, ballistic devices, other explosives and hypervelocity impacts. Armor systems of the disclosure may be used in conjunction with any vehicle, such as but not limited to, military vehicles, convoy vehicles and/or personnel carriers and may be useful to protect personnel and equipment in war zones.
On the battlefield, shape charges such as EFPs, also known as explosively formed projectiles, pose serious threat to equipment and personnel. EFPs and other shape charges may have the ability to pierce through the armor of a vehicle and injure or kill the occupants inside.
Various configurations of shape charges and EFPs have been developed and several are capable of penetrating extremely thick and heavy armor. Therefore, merely adding more armor layers to protect against a shape charge may result in a vehicle that is overweight and less effective on the battlefield. In accordance with a particular embodiment of the present disclosure, a lightweight armor system may be capable of stopping a projectile or significantly reducing its destructive capability.
While not wishing to be bound to any particular theory, the present section provides a brief description of how high energy explosives and shape charges may achieve their lethality. High explosives may be extremely powerful because of their ability to rapidly release energy in the form of heat and pressurized gas. The extremely fast rate at which this energy may be discharged gives a high explosive its strength. Rapid discharge of a large amount of energy into a small space may generate shock waves. For example, rapidly released energy may compress neighboring air or surrounding material that further increase its velocity. The compressed air may then rapidly propagate outward and create a shock wave.
When a high explosive is detonated, an explosion may begin at a small portion at the edge of the explosive. This explosion may create a shock wave that may propagate through the rest of the explosive. When this shock wave comes in contact with a portion of the high explosive that has not yet exploded the shock wave detonates the unexploded explosive. Thus, the additional explosion causes the shock wave to increase in velocity.
By exploiting the properties of a high explosive, in conjunction with certain geometric configurations, a more powerful and more focused blast may be accomplished. Shape charges utilize properties of high explosives and a conical geometric shape, lined with a metal liner, to achieve an explosion that can reshape material from the metal liner into a penetrating configuration at the same time accelerating it by a high energy explosion.
Inertial forces of a material (e.g., metal from a metal liner) that are being propelled by an explosion from rest to a hypervelocity may affect the Molecular structure of the material. A hypervelocity may be a velocity of over 6,700 miles per hour. Acceleration from rest to a hypervelocity generates extremely high inertial forces. These inertial forces may be significantly greater than the molecular forces holding the particular material together. As a result, the material may change its form and may convert from a solid to a liquid with the dominating inertial forces guiding the flow of the material.
EFPs and other shape charges use these principles while unleashing their explosive power. A shaped charge may be able to pierce a thickness of steel armor equal to six-times its diameter.
When a shape charge is detonated a shock wave that detonates the charge reaches the tip of its metal liner. The liner tip may accelerate forward due to inertial forces and reach a hypervelocity changing the solid metal into a fluid. As the shock wave pushes the liner metal fluid towards center and since there is already metal occupying the center, the metal gets pushed out in two directions, some of the metal gets thrust in the direction of motion and becomes part of the jet or the penetrating portion of the shaped charge, while the rest of the metal gets pushed back towards the explosive and becomes part of the slug, the slow bulky portion of the shaped charge.
The remaining part of the conical liner may take the shape of a flat sheet and the shock wave may then impart additional momentum to the flat sheet giving it a final solid push. The shaped charge finally detaches from its casing.
The fluid metal has a varying velocity with length velocity decreasing farther down. For example, a jet tip of the fluid metal may be traveling much faster than a slug. The result may be an ultra-fine long penetrator traveling at an extremely high speed which may go through armor with a thickness of about six times the diameter of the charge. In accordance with one embodiment of the present disclosure, the speed of the tip of a shape charge may be substantially decreased by using dilatant material within an armor system of the disclosure.
However, shaped charges are not as effective and efficient to pierce armor from a distance, since a jet of fluid material can continue to stretch and will eventually break apart before it contacts a distant target.
An EFP is a specific type of shaped charge designed to pierce armor from a distance. A wide range of EFPs have been designed depending on the desired effect. An EFP structure may provide a distinct aerodynamic advantage over shaped charges. EFPs are typically shaped as semi-spherical dishes (rather than conical shapes as described above) that may be covered by a metal liner. The metal liner may be copper, or any other suitable metal that behaves similar to a fluid when subjected to extremely high inertial forces.
By having a more shallow dish shape an EFP jet does not become quite as concentrated as a shape charge jet described in sections above. Often an EFP metal becomes a single slug rather than a separate slug and jet. A minor jet may be present near the tip, but for the most part, the slug does not have a defined shape. EFPs typically have a larger slug that stays together better, but may have lower penetration attributes. For example, an EFP may be able to pierce a thickness of steel armor equal to the charge diameter. However, an EFP liner may be concentrated together such that the metal does not break apart before it reaches its target, making it efficient to strike distant targets.
As set forth earlier, geometry of the curvature of the liner before detonation may control the shape an EFP changes into after detonation. Particular shapes may be found to provide optimum aerodynamic and penetration attributes. The shape of an EFP may be important to its ability to penetrate. An EFP with a smaller surface area may penetrate easier. This may be the result of the higher stress that the EFP imparts over a smaller surface area of the armor it is penetrating. This may result in greater penetration. In accordance with one embodiment of the present disclosure, surface area of the tip of an EFP may be increased by using dilatant material within an armor system. In some embodiments, increasing the surface area of the tip of an EFP may provide a technical advantage by making it easier to decrease and/or stop penetration by an EFP using a lightweight armor system.
An EFP may travel at hypervelocity regimes over 6,700 miles per hour. A shock wave that accelerates the metal liner to these types of velocities may cause the metal liner of an EFP to behave as if it were a fluid. Fluid effects caused by the inertial forces generated by the explosion may in part contribute to the EFPs ability to penetrate.
As the fluid from an EFP tip penetrates armor, the armor may exert a drag force upon the tip of the EFP. However, instead of transmitting this force throughout the entire EFP, as would occur if the EFP were a solid, the tip portion of the EFP that is subjected to the drag force, may fall away from the sides of a hole being created in the armor. Thus, instead of slowing down the entire EFP, only a small portion of the EFP may experience drag from the armor while the rest of the EFP maintains its velocity as it travels through the hole in the armor.
Additionally, as the portion of the metal tip gets dragged backwards by the armor, the EFP may reshape itself into a better penetrator. This may result when the edges of the EFP may be somewhat consumed as they are pushed to the rear of the EFP reshaping the EFP to become a thinner and more effective penetrator. For example, material from EFPs may be reshaped into a missile shape. The EFP, due to this reshaped form, effectively slides through the hole formed in the armor, as opposed to having large friction forces from the armor slow the entire EFP. Accordingly, an EFP effectively lubricates the armor walls through which it is penetrating and despite its poor initial shape, is effectively able to reshape and bore through thick armor. In some embodiments, an armor system using dilatant material according to some embodiments of the disclosure, may be able to reduce the reshaping ability of an EFP and cause the surface area of the front of an EFP to increase in size.
In addition, an EFP during its hypervelocity flight may split into a series of metal blobs or metal particles comprising leaders that are smaller, but travel faster and slugs which may be slower and bulkier. Several leader particles such as a primary leader and a secondary leader and several slugs such as a primary slug and a secondary slug may be present. A good EFP normally has all these metal particles well aligned with out a large pitch or yaw. Accordingly, an armor to protect form such an attack must be capable of withstanding multiple impacts.
Much of the lethal damage from an EFP is due to the behind armor effects (BAE). When an EFP penetrates armor, it may launch spall into the vehicle. Spall refers to the fragments of armor that the EFP may cause to break off and accelerate into the interior of the vehicle. This material may be extremely hot and may be moving at an extremely high velocity. As a result, these armor fragments may hit nearly everything within the personnel compartment of the vehicle and may cause extreme damage to the vehicle and equipment inside and injury or death to any occupants.
Damage from EFPs may also result from the overpressure blast that may send highly compressed air outwards at an extremely high velocity. The overpressure alone may cause blindness, deafness, and death. The overall effect of an EFP penetrating a vehicle may be similar to a fragmentation grenade being detonated within the vehicle.
In accordance with one embodiment of the present disclosure, an armor system using dilatant material may be capable of significantly reducing destructive capability of a shape charge, an EFP, a high explosive, as well as any high velocity impact by slowing the speed of the respective projectile device.
Armor layers 155 are generally used for armor against projectile 100. Armor layers 155 may be a sheet or panel. Non-limiting examples of armor layers 155 may include material comprising a metal alloy (e.g., steel, cast iron, titanium, etc.), easily yielding material, fiber made material, etc.
An easily yielding material may be a soft material, such as but not limited to a polycarbonate (e.g., a light weight plastic). Non-limiting examples of an easily yielding materials may include a material that may have very little structural support, such as but not limited to Styrofoam® and/or aerogels. An easily yielding material may be a material having strong structural support such as but not limited to carbonized hard steel. An easily yielding material in some embodiments may also include a naturally strong structural material for example a material comprising different shapes such as but not limited to honeycombs, cylinders, or pyramids. Use of several other easily yielding materials not expressly described herein are also contemplated and the present disclosure is not limited in any way to the examples listed.
Non limiting examples of fiber made materials may include e-glass, s-glass, an aramid fiber (such as Kevlar®), carbon nanotubes, carbon fibers, aluminum fibers, and combinations thereof.
Dilatant material 140 may also be used as armor against projectile 100. Dilatant material 140 may also be referred to as shear thickening material. Dilatant material 140 may be a non-Newtonian fluid because dilatant material 140 may not behave according to normal
Newtonian fluid dynamics. Dilatant material 140 may be in a liquid or solid state. Dilatant material 140 under normal conditions are generally in a liquid state, but dilatant material 140 may also look and act more like a solid under normal conditions. Dilatant material 140 may be a material where its viscosity increases with the rate of shear force applied to the material. The dilatant effect may occur when closely packed particles are combined with enough liquid to fill the gaps between the particles. At low velocities, the liquid in the dilatant material 140 may act as a lubricant, such that a slow moving object may move easily through dilatant material 140. However, at higher velocities, the liquid in dilatant material 140 may be unable to fill the gaps between the particles, which may cause friction and viscosity to increase, such that a fast moving object may not be able to penetrate through dilatant material 140. Thus, the viscosity of dilatant material 140 may increase when a force is applied to dilatant material 140. Non-limiting examples of dilatant material 155 may include material comprising a mixture of corn flour and water, a mixture of sand and water, a mixture of polyethylene glycol and silica, etc.
Dilatant material 140 may offer increased protection to armor system 150 when the increased force from projectile 100 is applied to dilatant material 140. When projectile 100 impacts with dilatant material 140, dilatant material 140 may become very hard as if it were a solid and may provide great resistance to projectile 100. The greater the force caused by projectile 100 with dilatant material 140, the harder and more viscous dilatant material 140 may become. For example, when projectile 100 impacts with dilatant material 140, dilatant material 140 may become as hard or harder than steel while weighing considerably less and being considerably less expensive than steel.
Layers of dilatant material 140 may cause the surface area of the front of projectile 100 to increase because the front of projectile 100 may become more flattened out while penetrating through dilatant material 140. After the surface area of the front of projectile 100 has increased as a result of traveling through dilatant material 140, the pressure applied to the next armor layer 155 may be lowered because the force of projectile 100 is spread over a larger surface area. Thus, projectile 100 may be stopped sooner because of the lower pressure applied to one or armor layers 155 as a result of traveling through one or more dilatant material layers 140. As a result, armor system 150 using dilatant material may require fewer layers of armor, which may result in lower weight and cost.
A layer of dilatant material 140 may also throw off the trajectory of an incoming projectile 100. For example, projectiles 100, which may often be missile shaped, although not necessarily limited to missile shaped objects, while penetrating through conventional armor systems, may be subjected to forces that may cause them to spin out of axis. However, since projectiles 100 may typically be fully constrained within the material of conventional armor systems, the projectile 100 may continue to stay aligned in its trajectory. However, when a projectile 100 is suddenly subjected to a layer of dilatant material 140 in armor system 150 in accordance with embodiments of present disclosure, the projectile 100 may gain a tumble.
In some embodiments, dilatant material layers 140 may be placed in a cavity formed between armor layers 155. In some embodiments, dilatant material layers 155 may be at least 0.25 inches thick. In some embodiments, one dilatant material layer 155 having a thickness of at least 0.25 inches may allow armor system 150 to remove an inch of steel to achieve similar protection, which may result in lower weight and cost.
In some embodiments, dilatant material 140 may be mixed into another armor layer 155, such that these armor layers 155 may receive similar benefits as discussed above. For example, an armor layer 155 of fiber made materials may be impregnated with dilatant material 140, which may give the fiber made materials greater strength and resistance to projectile 100.
In some embodiments, dilatant material 140 may be created and places in armor system 150 before impact by projectile 100. In some embodiments, dilatant material 140 may be created shortly before impact by projectile 100. For example, a bucket of water may be poured into a container of corn flour to create dilatant material 140. In some embodiments, dilatant material 140 may be created by using material in projectile 100 as an ingredient. For example, one or more ingredients may be placed in cavity of armor system 150 and those one or more ingredients may not form dilatant material 140 until exposed to the material from projectile 100. In particular embodiments, dilatant material 140a may be different than dilatant material 140b.
Projectile 100 may be any high explosive device, such as but not limited to a shape charge, an EFP, an IED, a landmine, a high energy explosive, a ballistic device and/or any hypervelocity impact. However, teachings of certain embodiments recognize that armor system 150 may provide protection or mitigate the effects of any other projectile type that may be operable to penetrate armor.
As further depicted in
Other armor systems that do not use dilatant material layers 140 between armor layers 155 as taught herein may be considerably heavier and thicker. For example, conventional armor systems, without using dilatant material layers 140 between armor layers 155 as taught in the present application, may be many inches thick at a minimum and may comprise layers of materials much heavier than dilatant material layers 140. In another example, the mere addition of two panels of armor to an existing conventional armor system may add an additional weight of about 20 lb/ft2 or more depending on the type and size of armor used.
If vehicle 20 were equipped with any existing armor system or armor system solution, its maneuverability and effectiveness in protecting against projectiles 100 as described here may be diminished. Teachings of certain embodiments recognize that armor system 150 may provide greater protection to shape charges by using a layer of dilatant material of at least 0.25 inches.
Modifications, additions, or omissions may be made to the systems and apparatuses described herein without departing from the scope of the invention. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. The methods may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. Additionally, operations of the systems and apparatuses may be performed using any suitable logic. As used in this document, “each” refers to each member of a set or each member of a subset of a set.
Although several embodiments have been illustrated and described in detail, it will be recognized that substitutions and alterations are possible without departing from the spirit and scope of the present invention, as defined by the appended claims.
To aid the Patent Office, and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims to invoke paragraph 6 of 35 U.S.C. §112 as it exists on the date of filing hereof unless the words “means for” or “step for” are explicitly used in the particular claim.
