Patent Application
20250027743
Provided herein are shaped charges, also referred to as a half-pipe disrupter (HPD). The HPD is a versatile scalable mass focusing high explosive shaped charge that can be used to disrupt improvised explosive devices (IEDs)/ordnance on land, buried beneath the land surface, or IEDs/ordnance below the waterline and submerged, including at depths greater than 100 feet. The HPD is configured to solve the gap of dynamically disrupting IEDs submerged in water. The HPD produces a focal linear fluid jet with a scalable cut length, which has a reduced risk of shock initiating an IED's explosives. The HPD can also be modified to increase penetration by defined depths without increasing impact pressures. The HPD is a disposable and low-cost solution for disrupting targets that are underwater or that are on the land.
One common scenario is a container or backpack, which may be lost or abandoned, washes up or gets entangled in any of the above referenced environments, structures, or watercraft. In the vast majority of incidents, the discovered items are determined not to be hazardous. If, however, the item is deemed suspicious or in the worst case is confirmed as an IED or bomb, a bomb squad or explosives ordnance disposal (EOD) team would respond. Most often, old ordnance, flares, or pipe bombs are discovered at the water bottom. The motives as to why pipe bombs are used in waters range from experimentation, explosives fishing, vandalism, terrorism, or murder. Preferably the object is towed and neutralized on land or far from critical infrastructure or people. At times, a bomb technician diver is needed in the water. In either case, there is a need in the art for a reliable disrupter that can be deployed to render safe the object that may be a bomb quickly in situ regardless of whether the bomb was towed on land or underwater. The HPDs provided herein address this need in the art.
A major challenge for responders to an IED response underwater is to analyze the item of concern and 1) determine if it is a bomb and 2) determine its structure and contents. For example, an underwater IED (UIED) may have sub compartments to control buoyancy, hold the explosives main charge, or to house fuzing system(s). Conventional methods of X-ray diagnostics cannot be performed underwater. Water currents, confined space, and water visibility are all limiting factors in analyzing the bomb's structures, weakness of design, and explosives/fuzing position. It is highly likely that a projectile fired from gun style disrupters/dearmers or high explosive shaped charges may hit the bomb's main charge or miss the fuzing system. Perforating a UIED to flood it may stabilize the bomb for movement but will not necessarily disrupt the fuzing system nor separate the firing train. Submerging power sources and conductors underwater for extended periods of time can degrade output; however, many tested power sources initiate electric matches hours to days later. To further understand the situation, initiation tests were conducted with the power source underwater with a water sealant applied to power sources to prevent degradation. Test results indicate that some fuzing systems immediately function when exposed to moisture or when immersed in water. Disrupters used in the field should address these issues. The experiments show that a disrupter must do more than flood an IED's container. Flooding may be ineffective at neutralizing a bomb's triggering mechanism, functionality, and may cause the fuze to function. A disrupter underwater must neutralize the fuzing and firing system of the IED.
Several issues arise from the limited diagnostics options underwater. The bomb's fuzing system can be missed by a projectile and there is a high probability of a disrupter projectile impacting a bomb's main charge. If the disrupter over pressurizes the IED container then it may burst. The IED's contents will escape the container. This result will make verification of a successful render safe difficult. Factoring in all the above issues and negative flooding effects, a high explosive mass focusing shaped charge should have the following characteristics for maritime operations: the jet should have the work function to disable the fuzing system, the jet height should cover the entire longest dimension of the bomb so as not to miss the fuzing system, the jet should be narrow in width so as to not over pressurize the bomb's interior and cause the container to burst, the jet should have a low risk of shock initiating the bomb's main charge, and the jet should not over penetrate the bomb which may be set against a structure such as a ship's hull. In addition, the disrupter's explosives should be minimized to prevent a large gas bubble that could cause a secondary blast effect known as bubble energy to damage a ship or structure.
There are several commercial and improvised shaped-charges that drive water and each have their strengths and weaknesses. A common method is to attach the explosives to a plastic former, which is either seated inside the fluid, sandwiched between fluid chambers, or is on the outside surface of the fluid container. Pressure fields are produced by shaping explosives into hemispherical, parabolic, linear (wedge or hemi-cylindrical), rod and conical charge geometries. When the explosives are initiated, shocks form inside the water column and reflect off of the free field surfaces. Various parameters such as angles and corners within the container of fluid or on the explosive former define the pressure-time history of the gases and shocks acting on the water. There are regions of high and low pressure that will differentially accelerate the water to form a jet. High pressure regions are due to a Mach-stem effect which are formed by collisions of shocks, usually along a central axis or plane. A slug or static volume of water is formed into the jetting projectile after the explosives initiation, and water behind the explosives traps the gases, and acts a tamp thus increasing the duration of pressure acting on the slug. Shocks can also reflect at the tamper boundaries and move back into the water, amplifying the pressure.
Water and other fluids can be driven explosively using shaped-charges to form liquid jets which move at relatively high velocity and can perform work on a target. Explosives are shaped and immersed in the water or placed on the outside of a water container. The explosives' detonation produces shock waves that move through the water. Typically, to create a jet, the charge is configured such that the shocks along a central axis or a bisecting plane converge and form a Mach stem. The pressure is higher in the center compared to the sides. A pressure gradient results in the water accelerating differentially as its position moves away from the center. The result is a jet that has a velocity profile with faster water at its front and the gradient is such that the water slows as one moves towards the explosive gas products. That velocity profile provides a number of challenges, including jet destabilization, gasification and atomization arising from shock waves in the fluid.
Accordingly, there is a need in the art for specially shaped-charges and multi-point initiation configurations that can further independently control one or more liquid jet parameters relevant for tailoring the shaped-charge to the specific application, such as controlling liquid jet tip velocity, jet cross-sectional shape, integrity, size and the like. This is important as different targets and operational conditions can be addressed with the shaped-charges provided herein so as to achieve desired outcomes in a safe and reliable manner, including for improvised explosive device disruption. The HPDs provided herein address this need.
The HPD provided herein is distinct compared to conventional high explosive shaped-charges that produce fluid jets. Conventional high explosive commercial and improvised shaped-charges that drive water will be described so that the reader can appreciate the differences with the instant shaped-charges, including HPD's. The simplest designs are for omnidirectional disrupters that use a rod or axially aligned central core of explosives that is hand-packed or pre-formed by an extrusion process. They drive water in a radially expanding fashion and the jet breaks up quickly due to hoop stress. In contrast, water jets can be focused using the common method of attaching sheet explosives to a plastic shelled former which is either seated inside the fluid, sandwiched between fluid chambers, or is placed on the outside surface of the fluid container. Pressure fields are produced by shaping sheet explosives into hemispherical, parabolic, linear (wedge or hemi-cylindrical), rod and conical charge geometries. When the explosives are initiated, shocks form inside the water volume and reflect from the free field surfaces. Various parameters such as angles and corners within the container of fluid or on the explosive former define the pressure-time history of the gases and shocks acting on the water. There are regions of high and low pressure that will differentially accelerate the water to form a jet. High pressure regions are due to the above mentioned Mach-stem effect which are formed by collisions of shocks, usually along a central axis or plane. The result is a focusing of the water mass and the jet travels a distance before breaking apart due to the stresses described above.
Omni-directional fluid driving high explosive disrupters are good at delivering high impulse to a target and drive water in all directions from the central axis. Generally, those tools have axial or translational symmetry. Omnidirectional tools produce low density jets that particulate into droplets. A commercially available disrupter that uses a similar approach to the Fast Loading Explosives Catenary Advanced Technology (FLExCAT) (U.S. patent application Ser. No. 18/338,170 filed Jun. 20, 2023) to maximize explosive density is the Blockshot™ (U.S. Pat. No. 9,470,499 titled “Explosive disruption container”). There is no hand-packing of the explosives and therefore maximizes the explosive density. The Blockshot™ has a single explosive core. The disrupter has a rectangular container with flat faces and an internal housing that holds approximately a ⅛ sectioned cuboidal piece of an M112 demolition block. Due to the large flat surface of the explosives relative to the container size, a planar shock is produced and thus provides some directionality to the water jet, but for the most part the water jet is omnidirectional. Other omnidirectional tools are the Cherry Engineering Inc.'s Mineral Water Bottle (MWB) charge, and the Alford Technologies' Bottler charge (U.S. Pat. No. 9,322,624). They use a hand-packed rod-shaped explosive charge at the center of a cylindrically shaped container. The MWB produces a radially expanding wall of water that exponentially thins with distance from the charge center and forms water droplets. The notable difference in the Bottler are three hemi-cylindrical indentations on the outer bottle surface. The majority of the MWB and Bottler container surfaces are convex in appearance from the perspective of one looking from the outside-inwardly. This convex geometry, however, results in release wave amplification and rapid loss of liquid water due to gasification.
Concavities or dimpling on the face of water charges have been shown to cause jetting. The container surface indentation creates a shock cavity effect and the fluid jets at the center of each concavity. Although this is not a primary function of the parabolic shape for the FLExCAT, it does contribute to jet formation. Concavities at container surfaces can cause linear jets if the containers have translational symmetry. The jetting is due to a reduced distance between the container surface and the explosive charge at the center of the concavity thus this liquid has higher pressures overall at the cavity apex. In addition, the pressure along the air-water boundary causes the liquid to move inward because the air is compressible, low density, and readily displaced.
Using plastic shaped sheets to create a surface to shape sheet explosives is a conventional method to mass focus water or HEET, including as described in U.S. Pat. No. 11,187,487. In the case of the Hydrajet™ (U.S. Pat. No. 6,269,725 (Cherry)), a tall pyramidal chevron-shaped wedge of sheet explosives with an apex angle of 90 degrees is placed inside a cylindrical shaped fluid-filled container. Cherry proposes an adjustable apex angle and a scalability in disrupter size. Another example of a linear charge is the mod series of disrupters (U.S. Pat. No. 6,584,908 (Alford)). In that case, rather than a wedge, it is an arc section of a curved shape. Alford et al. use two separate water chambers and sandwich sheet explosives between them. The jet profile is similar to the Hydrajet™. Those linear high explosive charges form blade shaped water jets. Based on flash x-ray and CTH modeling, a cross sectioning of the jet would have the profile that is approximately a narrow ellipse. Those tools show a good balance of impulse and penetration of small to medium-sized thin skinned IEDs.
Some water-based charges are more effective at perforating barriers such as liquid follow-through (LIFT) charges (U.S. Pat. No. 4,955,939). Conical LIFT charges may appear similar in shape to the CAT disrupter (U.S. Pat. No. 10,921,089), but have an air void in the location where the water slug would be present in the CAT disrupter. The CAT charge has a plastic shell to shape and layer sheet explosives. The shell has a parabolic base and truncated cone section nearest the rim. Conical disrupters and the CAT disrupter are axisymmetric and they form liquid jets that are circular in cross section. The explosives in the LIFT systems are cuboidal or cylindrical blocks placed at the rear of the disrupter and oriented so that a flat face is abutting the water. The detonator is positioned coaxially down the center of the charge. The explosive detonation wave shock couples at the water interface producing an approximate planar shock front that travels into the water surrounding the hollow cavity causing the water to collapse into the void and jet forward. The thin plastic liner collapses on itself and flows at the leading edge of the jetting fluid. Another example of a conical LIFT charge is the Rocksmith Precision Closer™ (U.S. Pat. No. 8,677,902). The cone angles are approximately 45 to 60 degrees and the jets are moving at extremely high velocities, traveling in some cases in excess of Mach 10. A larger example of a conical LIFT is the Scalable Improvised Device Defeat (SIDD) disrupter which can hold five gallons or more of water.
An example of a linear LIFT charge is the Stingray™ (U.S. Pat. No. 8,091,479) and a similar collapsible charge (U.S. Pat. No. 9,429,408). The cuboidal explosive charge is placed at the back of the disrupter and has no fluid tamping. The water surrounds a ‘U’ shaped profiled cavity. The container lines the inside of the cavity and collapses to form a plastic slug that jets forward with some water following behind it. LIFT charges generally produce narrow fluid jets of low mass. They have high jet stretch rates and are good barrier penetrators but yield low bulk work on media and low impulse in experiments. As a result, they are relatively poor general disruption tools.
Linear shaped-charges typically have translational symmetry and will result in a perforation that is proportional to their length. Due to this translational symmetry, shaped-charges can be scaled along the symmetry line while keeping the other dimensions constant. This results in the same quantity of explosives per unit length and a jet that has no height limitations. Thus, a jet can cover the height of the entire bomb or target. Linear scaling of the disrupter length produces a small increase in jet velocity and an increase in target penetration, thus the disruption metrics for a linearly scaled charge to its original size is approximately the same. A disrupter can be translationally scaled up, for example, to cut a house door in two or scaled down to cover the height of a shoebox-sized bomb. The advantage is minimizing the weight of the fluid-filled charge because the weight growth is linear. A key advantage of a linear disrupter jet covering the entire height of a bomb is that the jet will have a higher probability of hitting fuzing components and destroy them because their position may be unknown. In contrast, axisymmetric charges cannot be translationally scaled to improve the perforation height, but instead radially scaled to increase the cross-sectional area of the jet resulting in a radius squared dependent increase on fluid mass. The axisymmetric charges produce long jets that greatly enhance penetration depth compared to linear charges. Thus, linear charges have to be placed closer to the target.
The HPD mass focusing shaped charges provided herein are linear shaped charges that can be conveniently scaled geometrically or translationally and that are readily “tuned” to the target, including a target environment that is underwater or on land, in a low-cost, safe and effective manner. The HPDs address the need in the art for a versatile disrupter platform that can be used underwater (e.g. creeks, rivers, ponds, lakes, seas, or oceans) or on dry land/above the water line (e.g. ship decks, docks, bridges, tunnels, roads, structure interiors, inside transportation modes), with the ability to tailor jet parameters depending on the target and environment.
The mass focusing shaped charges provided herein address the need in the art for further independent control of one or more liquid jet parameters depending on the application of interest, including target type and target environment, spanning from underwater to land-based applications, in an efficient and easy to use manner. A preferred mass focusing shaped charge is a HPD.
In an embodiment, the mass focusing charge is used to disrupt a target, and comprises an explosives shell having an explosives shell surface having an inside surface and an outside surface. The inside and outside surface are separated by the thickness of the explosives shell. The term explosives former is also used to functionally describe the aspect that the inside shell surface supports an explosives material. The explosives shell may have a sectioned profile that is at least partially curved. For example, an HPD has a curvature at least partially corresponding to a hemi-cylinder. There are one or more symmetry planes in the explosives shell to ensure formation of a stable jet. The explosives shell has an inner volume defined by the explosives shell inside surface configured to contain an inner volume of fluid and a distal opening. During use, it is preferred that there be a structural confinement at the distal opening that further defines the inner volume. Accordingly, a distal body is connected to the explosives shell distal opening to close the inner volume and contain the inner volume of fluid. Preferably, the distal body comprises a surface material attenuation of rarefaction technology (“SMART”), (including as provided in US Pub. No. 20240068767, which is specifically incorporated by reference herein) material that is positioned between the inner volume of fluid and the target. The HPD is unique in that it is a high explosive shaped charge that uses a SMART material in this manner. The explosives shell is immersed in a fluid body. Depending on the application of interest, the fluid body may correspond to or be different than the fluid in the explosives shell inner volume. A conformable layer of explosives conforms to at least a portion of a surface of the explosives shell, preferably the explosives shell inner surface. The conformable layer of explosives is configured for explosive initiation by a detonator, such that upon explosive initiation the inner volume of fluid is configured to implode and form a fluid jet that is forced in a direction through the distal body toward the target. The fluid jet is relatively narrow compared to other conventional disrupters and wedge-shaped. The fluid jet will perforate a target along a line that is proportional to the axial length of the HPD's explosives shell.
The fluid body may form the inner volume of fluid. For example, the ends of the explosives shell may remain open so that when the explosives shell is immersed in the fluid body, the fluid body floods the inner volume. Alternatively, the inner volume of fluid may be formed from a liquid that is different than the fluid body. In this embodiment, the inner volume may be completely sealed from the fluid body, so that upon immersion in the fluid body, the inner volume is not flooded by it.
The at least partially curved explosives shell section profile may be defined by a geometric equation, including an equation that is selected from the group consisting of: a semicircle; a parabola; two equal length lines that end at an intersecting apex; a line; and any combination thereof. For example, a portion of the surface may be linear and another portion a parabola. The section profile, therefore, corresponds to a 3-D shaped surface described as: a hemicylinder, a paraboloid, a wedge, a cone, and any combination thereof.
The SMART material may be selected from the group consisting of: rigid polyurethane, a vinyl closed cell foam, a polyvinylchloride foam, and a structural foam.
The inner volume of fluid may have a fluid volume corresponding to a closed surface formed between the explosives shell and the SMART material.
The SMART material may be formed into: a cuboid geometry; or a proximal surface with a profile corresponding to an arc, paraboloid, or a pyramidal geometry. In embodiments, the SMART material may be stand-alone and so correspond to the distal body, or may be contained within a distal body container, including a SMART box. The distal body container may have an injection fill hole for introducing the SMART material. For example, an expanding polyurethane foam may be injected through the fill hole and expand to take up the entire interior volume of the SMART box.
The explosives shell is preferably curved and has a bisecting symmetry plane.
The explosives shell may be formed of a material that is flexible to provide an adjustable curvature by changing the radius of curvature of the explosives shell.
The SMART material may comprise a plurality of SMART layers, including a distal-most layer that is a jet clipper and at least one layer that is not a jet clipper.
The mass focusing shaped charge may further comprise a coupler connected to an outer surface of the explosives shell to connect to another mass focusing shaped charge in an end-to-end configuration. In this manner, the shaped charge is readily scaled to match any target size. In other words, by use of the couplers to connect in series configuration any number of shaped charges, the fluid jet height is increased and matched to target height, where height is the linear dimension that is parallel to the longitudinal axis of the HPD explosive shell. This is important because undersized jets comparted to target increases risk that target will not be disabled, including by jet miss of a critical target component, such as a fuzing system.
The mass focusing shaped charge may further comprise a connector to connect the mass focusing shaped charge to a target. The connector type depends on target characteristics. Examples include one or more of: a magnet; an adhesive; a flexible tripod; a strap such as a ratchet strap that can traverse outer perimeter of the target and shaped charge to tightly hold the shaped charge to the target; and any combination thereof. These connectors reflect that in various embodiments it is preferred to minimize the amount of fluid body between the shaped charge and the target. Accordingly, the distal body and/or SMART material is preferably positioned in such a way that it occupies the space between the shaped charge on the target. Accordingly, the connector can be affixed to the distal surface of the shaped charge, such as a distal surface of the distal body or the distal surface of the SMART material. For SMART material that is provided within a container that is formed by the distal body, such as a SMART box, the connector may be affixed to distal surface of the distal body or SMART box. Of course, depending on the connector, there may be different points of connection that are not the distal surface. For example, a ratcheting strap that tightens to hold the shaped charge to the target may not even contact the shaped charge distal surface.
In other embodiments, particularly for dry land-based applications, the mass focusing shaped charge may further comprise a container having a container volume to contain the “rest” of the mass focusing shaped charge as well as the fluid body. In other words, the container holds the fluid body, and the shaped charge is at least partially or completely immersed in the fluid body held by the container, thereby surrounding the explosives shell. The container can have a seal to contain the fluid body in the container volume, wherein the seal is optionally a threadable lid or a snap-on lid. Alternatively, or in addition thereto, a container may be configured to contain the inner volume of fluid and container with inner volume of fluid configured to fit and occupy the explosives shell inner volume.
The mass focusing shaped charge may further comprise one or more buoyancy control plates connected to the explosives shell or distal body. For example, sleeves may be connected to an outer surface of the shaped charge for convenient loading/unloading of buoyancy plates depending on the target depth beneath the water surface.
The mass focusing shaped charge may further comprise a firing train comprising a single detonator operably connected to the conformable layer of explosives, wherein the firing train is configured to provide a single point or multi-point explosive initiation of the conformable layer of explosives comprising one or more sheet explosives strips.
The mass focusing shaped charge may be configured to have a single point of initiation in an initiation zone that is on a longitudinal axis at a curvature apex at one of the following locations: at a charge center of the sheet explosives strip; or adjacent to a boundary edge of the sheet explosives strip.
The mass focusing shaped charge may further comprise a tow line attachment connected to an outer surface of the explosives shell or the SMART material. The connection point is simply any accessible region to a user who may clip and unclip a tow line. Accordingly, outer surface is any accessible location that does not adversely impact fluid jet formation. Hence side surfaces away from the distal surface are preferred, including on the side of the distal body or SMART box.
The mass focusing shaped charge may further comprise a locking fastener connected to the explosives shell surface to reliably fasten the detonator and configured to provide strain relief for an electric leads or shock tube lead of the detonator.
The mass focusing shaped charge may further comprising a sealable container that is operably connected to the explosives shell, the sealable container having a surface shape that aligns with the conformable layer of explosives; wherein the sealable container is filled with the inner volume of fluid that is positioned in the explosives shell inner volume. In this manner, the sealable container may provide the distal body and distal body surface as well as containing the inner volume of fluid.
The explosives shell may be formed of a material comprising plastic, steel, copper, aluminum, or brass. For material subject to fragmentation hazard, the conformable layer of explosives preferably comprises: an outer explosives layer; and an inner explosives layer. In this manner, the inner and outer explosives layer together counteract the otherwise explosive ejection of the shell.
The mass focusing shaped charge may further comprise a SMART tamp that covers the outer explosives layer, wherein the SMART tamp is formed from a natural or synthetic rubber whose density is equal to or greater than that of water, including for example by a factor of 1, 1.5, 2 or 3, such as by a factor that is greater than 1 and less than or equal to 3, and any subranges thereof. The maximum density is preferably less than or equal to the density of steel.
The mass focusing shaped charge is configured to be geometrically and/or translationally scaled proportionally relative to a height, a depth along a jet trajectory, or a barrier thickness of the target for controllable adjustment of at least one of the following target disruption parameters: a target barrier perforation; a target depth of penetration; an impact pressure; or a jet velocity. One simple scaling system connects multiple shaped charges to each other, such as by a fastener or a coupler. Geometric scaling increases penetration and impulse by the scaling factor, but does not change the jet velocity and thus the impact pressure. The impact pressure is proportional to the square of the jet velocity. To expand on the scaling concept, the translational scaling can be such that the ratio of the adjustable height of the HPD to the fixed radius is 1, 2, 2.5, 3, 4 or 10 for example. Using geometric scaling, the height and radius are scaled equally such that the scaling factor is 1.5, 2, 2.5, 3, 4 or 10 for example.
The mass focusing shaped charge may have a dimension of the shaped charge that is fixed, but the amount of the conformable layer of explosives is selected to control at least one of the following target disruption parameters: target barrier perforation; target depth of penetration; jet stretch rate; impact pressure; and/or jet velocity. Increasing the explosives per unit area of the conformable layer, correspondingly increases the aforementioned target disruption parameters. In this manner, provided are methods of adjusting a target disruption parameter by adjusting the amount of explosives per unit area of the conformable layer.
The mass focusing shaped charge may be used on land, including by incorporating the shaped charge into a fluid-filled container. In this embodiment, the distal body may be formed from a portion of a container that surrounds and contains the explosives shell and fluid body. For example, an inner facing surface of the container may have a portion to which the explosives shell is supported. Opposed to the supported explosives shell may be the SMART material that is positioned on the outer facing surface of the container. In this aspect, the distal body is functionally the container portion that is the wall sandwiched between the explosives shell and the SMART material, in combination with the SMART material.
Also provided are more conventional mass focusing shaped charges that do not require a liquid and are particularly well-suited for reliable and robust transit across an air gap, penetration through Earth by a penetration depth, and corresponding target disruption for a target that is buried in Earth. For example, in this embodiment the mass focusing shaped charge may comprise an explosives shell having: an explosives shell surface having an inside surface and an outside surface; an explosives shell sectioned profile that is at least partially curved; one or more symmetry planes; an inner volume defined by the explosives shell inside surface; a metal liner supported by the explosives shell inside surface; a first SMART material supported by the explosives shell outside surface; a conformable layer of explosives that conforms to at least a portion of the inside surface of the explosives shell, the conformable layer of explosives configured for explosive initiation by a detonator; a metal liner (e.g., relatively thin, such as between 0.04″ and 0.25″, including between about 0.0625″-0.125″) supported by the conformable layer of explosives and positioned so that the conformable layer of explosives is sandwiched between the metal liner and the explosives shell; a second SMART material supported by the metal liner, wherein the second SMART material occupies the inner volume of the explosives shell. With this configuration, upon explosive initiation (e.g., via a detonator) the metal liner is crushed and flows as a jet having a blade geometry toward the target.
A stand may be used to align the shaped charge with a target. The target may be on land. The target may be buried. The target may by partially buried. A stand may be used to properly align the shaped charge so as to generate a fluid jet the will disrupt the target. The fluid jet may traverse an air environment, such as traversing through air corresponding to the stand-off distance.
Also provided herein are methods of disrupting a target using any of the mass focusing shaped charges described herein. For example, the method may comprise the steps of: providing any of the mass focusing shaped charges described herein; aligning the mass focusing shaped charge with a target; and detonating the conformable layer of explosives to explosively drive a mass toward the target. For embodiments where the mass is a liquid, the mass corresponds to a liquid jet from the inner volume of fluid. For embodiments where the mass is a metal liner, to the target in a fluid jet; thereby disrupting the target.
Also provided are methods of making any of the mass focusing shaped charges described herein.
The terms IED hazardous device, bomb, and ordnance are used interchangeably herein and are more generally referred herein as a “target”.
“SMART” refers to a surface material attenuation of rarefaction shock waves material, including those materials described in US Pat. Pub. No. 2024/0068767, which is specifically incorporated by reference herein. In particular, a SMART material is an attenuating body configured to impact reflected shock waves that are otherwise propagated in the contained liquid and interact with liquid/wall interfaces. One example of a SMART material is a foam. “Foam” refers to a material that is formed by trapping pockets of gas in a liquid or a solid. A solid foam can be closed-cell or open-cell, depending on whether the pockets are completely surrounded by the solid material. In an open-cell foam, gas pockets connect to each other, including via pores. In a closed-cell, gas pockets are not connected to each other. The foam is polydisperse and is characterized as not uniform and stochastic. Foams efficiently attenuate shockwaves because of the heterogeneous structure in combination with low bulk density. In this manner, pressure waves are broken up and dispersed, thereby providing good shock tamping. Depending on the application of interest, which influences the desired liquid jet characteristics, the foam can be made from any of a range of materials, such as plastic, rubber (natural or synthetic), aluminum or other metals. For example, blasting cap protectors are made from aluminum foam because an aluminum foam absorbs the shock. The attenuating body may also be an aerogel. “Aerogel” refers to a synthetic porous material derived from a gel, where the liquid component has been replaced with a gas without significant collapse of the gel structure. Exemplary aerogels include, but are not limited to, solid smoke, solid air, solid cloud, blue smoke, silica aerogels, carbon aerogels, polymer-based aerogels, metal-oxide aerogels, and the like.
Bomb technicians and EOD technicians responding to an item suspected to be a bomb or confirmed IED may have to dive and conduct a render safe procedure below the water line. Water environments can be waterways such as seaways, harbors, ports, canals, or channels. Examples of freshwater or brackish environments are ponds, creeks, flooded quarries, and lakes. Larger bodies of water composed of saltwater are seas and oceans. Depths can range from near surface to 200 feet below. However, depths for bomb squad or EOD response are typically within 50 feet of the surface. A potentially hazardous object may be attached to or be positioned in close proximity to a pier, a bridge, a culvert, a boat or ship, or a submerged pipeline or power-line. Limpets and floating mines may have anti-disturbance, anti-intrusion, or anti-removal mechanisms that will trigger them to function. Mines can also have proximity sensing mechanisms such as metal detection, pressure wave, or contact action. Furthermore, IEDs that are in a water environment may also be time or command initiated.
The HPD gets its name from the embodiment that uses a hemicylindrical shaped shell for the explosives former. Construction is low cost because plumbing lines made from plastic PVC pipe, copper, brass, or steel pipe can be easily bisected forming two hemicylindrical surfaces. Any commercially available round-tube, plumbing pipes, and sewer pipes can be cut to form the hemicylindrical shape explosives shell (
Curved embodiments can be made from bent pipe fittings such as elbows with bends ranging from 22.5°, 45°, 60°, 90°, and 120°. Flexible piping such as those used in drainage systems provide a continuum of radial curvatures and corrugated piping will retain the curvature set by the user and can be adjusted in the field during an active operation. For IEDs and ordnance having curve profiled bomb casings or cylindrical sections, the bomb technician can use a flexible or rigid HPD to match the curvature. For example,
An explosives shell curved section profile is preferably a hemicylindrical shape because this shape is the most efficient geometry for mass focusing disruption. This is because a hemicylinder requires the minimum amount of sheet explosive for a given volume of material that is being explosively driven. The explosive gases shock and implode fillers such as water, semi-solids, fine granular material, or HEET fluids to form high velocity jets as based on the calculated ratio of volumes using different profiled explosives shells of the same area. A very common shape is a wedge/chevron shape that forms a triangular prism volume. Mathematically, the apex angle required to create the maximum volume is 90°. The closed volume defined by a hemicylindrical surface with the same surface area as the triangular prism is 1.27 times larger. This means that for a given amount of explosives the hemicylinder explosives will drive a jet with approximately 27% more mass. The other advantage of this hemicylindrical shape is the higher generated pressures due to the mach stem effect and the focusing of shocks to a center line that is equidistant radially. This line is in the bisecting plane and so a relatively narrow blade shaped jet forms.
The HPD is characterized as a linear shaped charge and can be scaled translationally, geometrically, or scaled by using a hybrid of the two scaling methods. Linear shaped charges form jets that are preferably the dimension of the charge in the symmetry axis direction. In addition, thickness/mass of sheet explosives are adjusted to modulate the jet tip velocity and jet stretch rate. Penetration is directly proportional to the length of the jet measured from jet tip to rear. Controlling penetration is important in a maritime environment. A beneath the surface (BTS) render safe procedure should effectively disrupt the bomb and cause minimal dispersal of components and controlled penetration depth to prevent significant damage to adjacent infrastructure or a boat/ship. It is impossible to confirm a bomb was neutralized if the explosives and fuze are lost underwater. The HPD is configured to minimize cavitation. Displacing large volumes of material inside the IED would cause it to violently rupture and expel its contents. In contrast, most other commercially available mass focusing disrupters cause considerable cavitation.
The HPD provided herein is configured so that the height dimension can be independently changed without changing the jet characteristics. If desired, the jet will perforate the IED from end-to-end. Another advantage of the instant HPDs are that they are scalable in height to whatever height is required. For example, a typical minimum height may be 4″. The HPD can be readily configured to achieve, for example, an 11″ in height, to cut a 50-caliber ammo can bomb completely along its long axis. Or, the HPD can be configured to generate a 35.5″ in height jet to cut a 55 gallon drum skin completely along its long axis. A cut equal to the bomb's long axis dimension increases the probability that the jet disrupts the bomb's fuzing system and separates the firing train. By scaling the height of the tool without changing other parameters, the depth of penetration is fixed. HPDs can be cut to a specified height, or one embodiment is telescoping such that an HPD can be stretched from between 4″ and 8″, or 8″ to 16″, or any long axis dimension. Another simple solution to translationally extend the HPD to match a larger target is to use a coupler, such as connector 90 to lock two HPDs 1 together in an adjacent configuration (
Alternatively, the cut height can be fixed and the depth of penetration adjusted. There are several ways this can be accomplished. One method is by geometrically scaling all dimensions but the height of the explosives shell. The benefit of this method is the velocity profile of the jet does not change and so the impact pressures remain the same. IEDs generally have impact sensitive explosives inside them and the impact pressures that shock the IED's main charge are proportional to the jet velocity squared. Geometric scaling also increases the barrier limit thickness, which means if a two-inch radius HPD disrupter can cut through 20-gauge steel and three-inch radius disrupter can cut through 18-gauge steel, and a four-inch radius disrupter can cut through 16-gauge steel without increasing the jet tip velocity. A second method to increase the barrier limit thickness is by increasing the sheet explosives mass/unit area or changing from a PETN-based sheet explosives to an RDX-based sheet explosives; the former has a 63% by weight explosives content and the latter has a 92% by weight explosives content. Furthermore, RDX has a higher specific energy than PETN.
Using a curved or bent HPD can focus shocks and pressure toward the center is another method to increase penetration. The result is a jet that focuses inward and, because the same mass of water is accelerated, the jet narrows in height but extends in length. Penetration is directly proportional to jet length. In addition to increasing penetration, there are other beneficial aspects of bent and curved HPDs. An issue with center priming an HPD is that the explosive pressure increases with distance from the center as the detonation wave moves towards both ends of the charge. There is a distance to run before the detonation reaches steady state. The detonation velocity grows. In addition, the pressure builds and self-confines behind the propagating wave thus increasing it. As described, using a SMART material at the distal end (e.g., “front”) of the inner volume of fluid (“water slug”), reduces this effect and helps the water to bunch which results in a more uniform velocity in the linear jet tip. We observe in CTH hydrocode that without the use of a SMART material, the center of the linear jet has a slower velocity than the jet zone nearer the ends of the linear jet front. Similar to light waves, there is a refractive effect between the detonation wave and the shock wave in the fluid. The refractive behavior is similar to what is described in Snell's law which dictates light bending when passing from one media to the next. The shock wave will be at a relative angle to the detonation wave. The sine of the angle is equal to the ratio of the velocities. The fluid will move in the direction of the shock wave. The result is the water isn't pushed normal to the long axis of the charge, but will move at the angle. This angle is referred to as the Taylor projection angle (
At a critical curvature defined by the radius, the water within the jet travels all in the same direction toward a target (
Penetration is optimum when the water jet has a uniform particle velocity from top to bottom and, therefore, an important embodiment for the mass focusing shaped charge is an explosives shell having a critical radius of curvature for the explosives shell curved section profile 16. So that the jet travels in one direction toward the target in a shape that is generally wedge-shaped. An example of a mass focusing shaped charge 1 with a critical radius to its curvature is provided in
One important aspect of the mass focusing shaped charge is that the inner volume of fluid and the tamp are both formed by the water in which the charge is placed. No container is needed for such underwater embodiments. For example, immersing the mass focusing shaped charge into a pond results in the pond water flooding the region adjacent to the explosive shell to form the inner volume of fluid. The surrounding pond water acts as a semi-infinite tamp. The mass focusing shaped charge 1 can be converted to a traditional dry land-based mass focusing disrupter by immersing the shaped charge inside of a sealable container 100 that holds a fluid (
For land-based operations, when the mass focusing shaped charge is fired, the inner volume of fluid perforates the distal body and exits the shaped charge in the form of a fluid jet in the surrounding air environment. The fluid jet may travel an unconfined distance through air, corresponding to a set-off distance between the shaped charge and the target, and subsequently strike the target surface. In this aspect, target parameters and standoff distance are important aspects for successful IED disruption.
For conventional mass-focusing disrupters used on land, the fluid jet forms in air before it hits a target IED. Examples of traditional linear mass focusing disrupters are the Hydrajet which uses a chevron shaped explosives shell, the Demimod which uses a curved section profile shaped explosives shell, and the axisymmetric disrupter known as the catenary advanced technology (CAT; see, e.g., U.S. Pat. No. 10,921,089) which uses a radially symmetric explosives shell that is a truncated cone capped with a catenoid. Those disrupters use specific containers to close the volume of water surrounding the explosives shell. In the case of the Demimod, the tamp water is in one sealed container and the water slug is in a second sealed container. The explosives are sandwiched between the two containers when they are mated. For the Hydrajet, the commercial container is approximately cuboidal and the chevron-shaped explosives shell's bisecting plane is collocated in the bisecting plane of the container. The container shape is critical for stable jet formation. The water-air interface affects jet stretch rate and gasification of the water volume. This is because of the rarefaction waves that reflect off the distal surface of the container. In contrast, due to the use of SMART material, the HPD is not dependent on specialized containers because the rarefaction waves are attenuated by the SMART material and jet bunching occurs at the SMART interface. When used on land, any container shape and size can be used. For example, a paint bucket, or a cuboid-shaped peanut jar, or an hour glassed shaped container with biaxial symmetry can be used. The orientation of the HPD symmetry plane relative to the container symmetry plane doesn't matter. However, some orientations are better than others. For example, an HPD positioned such that the SMART material is adjacent to the flat base of a bucket, is better than placing the HPD such that its longitudinal axis is parallel to the longitudinal axis of the bucket.
A jet will not form effectively by immersing any of the conventional referenced disrupters underwater. The ideal penetration equation predicts that a water-filled disrupter penetration through the open water medium is equal to jet length. If the jet is four inches in length, then it will erode away within four inches. Conventional disrupters are typically positioned with a standoff that is the width or diameter of the charge. A disrupter that is four inches wide would be placed four inches from the target. The jet will be exhausted before it reaches the target. Another consideration is the shock effects that are important in jet formation. In conventional disrupters, there is a water-air boundary at the fluid container wall. The shock wave generated by the explosive detonation reflects off the front face of the disrupter. The reflected wave is a rarefaction wave, which contributes to the velocity gradient within the water mass that adversely impacts the fluid jet characteristics. There is no rarefaction wave if the disrupter is immersed in a water environment. The water mass will pile up on itself and be projected mostly as unit mass rather than jet. The expansion and contraction of the explosive gas bubble would be the primary cause of target damage. To solve the issue of jet erosion in water and to produce the rarefaction wave, the mass focusing shaped charges provided herein can use SMART material(s) 70 to displace the water between the shaped charge distal surface and the target (
Examples of SMART materials include, for example, a closed cell rigid foam such as Fiberglast™ or a polyurethane foam. The optimal foam density is approximately 3 lb/ft3. As noted above, the SMART material is beneficial because it attenuates the intensity of the rarefaction wave. Structural foams that have high compressive strength are necessary because at depth, the water pressure will cause foam to shrink. Experiments using Styrofoam showed that the foam shrank to half its volume at 33 feet (1 Atm) under water. Styrofoam is not characterized as a SMART material because it has no shock benefits. Furthermore, as noted above, it cannot retain its shape and shrinks when submerged making it impractical for underwater operations.
Referring to
In this example, the mass focusing shaped charge is end initiated. The explosive shell can have ports or channels, referred here as priming channels 131 (see, e.g.,
A variety of detonator attachment methods can be used. In
A diver who is carrying a shaped charge 1 such as a HPD underwater may have to deal with water currents, and poor visibility.
Multipoint initiation along the HPD apex or at four or more points on the sheet explosives can cause detonation waves to collide. Furthermore, multipoint initiation is a way to approximate instantaneous initiation of the explosives. The result is a more uniform and stable jet having a higher jet tip velocity. In
Another technique to prevent undesirable initiation due to shock coupling is shown in
The explosives shell 10 contributes to tamping. No other mass focusing charge uses the explosives forming shell in this way. A common property that improves tamping is material density. PVC, for example, is 1.35 times denser than water; steel and copper are approximately 8 and 9 times denser than water, respectively. Steel and other metals, however, present a fragmentation hazard when they are used in the explosives shell above the water line or on dry land. This problem is addressed by explosively force balancing the reaction force of the main charge to cancel the acceleration and expansion of the metal shell. An identical or slightly higher amount of sheet explosives is wrapped on the opposite side of the explosives former (
For land-based operations, the design shown in
In other embodiments, including as exemplified in
The examples provided in
This patent application claims benefit of and priority to U.S. Provisional Patent App. Nos. 63/527,781 filed Jul. 19, 2023 and 63/601,008 filed Nov. 20, 2023, each of which are incorporated by reference herein.
This invention was made at least in part with U.S. government support under 15F06721D0003094 awarded by the Federal Bureau of Investigation. The U.S. government has certain rights in the invention.
| Number | Date | Country | |
|---|---|---|---|
| 63601008 | Nov 2023 | US | |
| 63527781 | Jul 2023 | US |
