Abstract
Provided herein are mass focusing shaped charges and related methods useful for disrupting targets in either underwater or on land. The mass focusing shaped charges comprise an explosives shell having an explosives shell surface, wherein at least a portion is curved and defines an inner volume configured to contain an inner volume of fluid or a metal liner. A distal body is comprising a SMART material is positioned between the inner volume of fluid and a to-be-disrupted target. A conformable layer of explosives conforms to at least a portion of a surface of the explosives shell, the conformable layer of explosives configured for explosive initiation by a detonator. Upon explosive initiation the inner volume of fluid or metal liner is forcefully ejected to form a fluid or metal jet in a direction through the distal body and toward the target.
Claims
1. A mass focusing shaped charge to disrupt a target comprising: 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 configured to contain an inner volume of fluid; a distal opening; a distal body connected to the explosives shell distal opening to close the inner volume and contain the inner volume of fluid, wherein the distal body comprises a SMART material that is positioned between the inner volume of fluid and the target; a fluid body, wherein the explosives shell is immersed in the fluid body; a conformable layer of explosives that conforms to at least a portion of a surface of the explosives shell, the conformable layer of explosives configured for explosive initiation by a detonator; wherein 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.
2. The mass focusing shaped charge of claim 1, wherein the fluid body forms the inner volume of fluid.
3. The mass focusing shaped charge of claim 1, wherein the inner volume of fluid is formed from a liquid that is different than the fluid body.
4. The mass focusing shaped charge of claim 1, wherein the at least partially curved explosives shell section profile is defined by a geometric 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.
5. The mass focusing shaped charge of claim 1 wherein the SMART material is selected from the group consisting of: rigid polyurethane, a vinyl closed cell foam, a polyvinylchloride foam, and a structural foam.
6. The mass focusing shaped charge of claim 1, where the inner volume of fluid has a fluid volume corresponding to a closed surface formed between the explosives shell and the SMART material.
7. The mass focusing shaped charge of claim 1, wherein the SMART material is formed into: a cuboid geometry; or has a proximal surface with a profile corresponding to an arc, paraboloid, or pyramidal geometry.
8. (canceled)
9. The mass focusing shaped charge of claim 1, wherein the explosives shell is formed of a material that is flexible to provide an adjustable curvature by a changeable radius of curvature.
10. The mass focusing shaped charge of claim 1, wherein the SMART material comprises 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.
11. The mass focusing shaped charge of claim 1, further comprising 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.
12. (canceled)
13. The mass focusing shaped charge of claim 1, further comprising a container having a container volume to contain the mass focusing shaped charge and the fluid body contained by the container surrounds the explosives shell, wherein the container has a seal to contain the fluid body in the container volume, wherein the seal is optionally a threadable lid or a snap-on lid.
14. (canceled)
15. The mass focusing shaped charge of claim 1, further comprising 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.
16. The mass focusing shaped charge of claim 15, having 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.
17. (canceled)
18. (canceled)
19. The mass focusing shaped charge of claim 1, 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.
20. The mass focusing shaped charge of claim 19, wherein the explosives shell is formed of a material comprising plastic, steel, copper, aluminum, or brass, wherein the conformable layer of explosives comprises: an outer explosives layer; and an inner explosives layer; that together counteract an explosive ejection of the shell.
21. The mass focusing shaped charge of claim 20, further comprising a SMART tamp that covers the outer explosives layer, wherein the SMART tamp is formed from a natural or synthetic rubber.
22. The mass focusing shaped charge of claim 1 that is 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.
23. (canceled)
24. The mass focusing shaped charge of claim 1, wherein the target is a land-based target with air positioned between the mass focusing shaped charge and the target, wherein: the distal body is formed from a portion of a container that surrounds and contains the explosives shell and fluid body; the SMART material is positioned on an outer facing surface of the container and between the explosives shell and the target.
25. A mass focusing shaped charge for disrupting a target comprising: 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 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; wherein upon explosive initiation the metal liner is crushed and flows as a jet having a blade geometry toward the target.
26. A method of disrupting a target, the method comprising the steps of: providing a mass focusing shaped charge of claim 1; aligning the mass focusing shaped charge with a target; detonating the conformable layer of explosives to explosively drive the inner volume of fluid to the target in a fluid jet; thereby disrupting the target.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1 illustrates explosives shell sectioned profiles of several embodiments. The profiles are curved and can be described generally as hemicylindrical, parabolic, and a complex geometry formed of a linear profile that transitions to a parabolic profile and then back to a linear profile.
[0047] FIG. 2 illustrates an HPD that is immersed underwater. A curved HPD is oriented radially to a target that is a bomb in order to sever the fuze head from the main charge of a bomb. In this case, the bomb is underwater and the HPD inner volume is flooded by the fluid body. The water environment provides a semi-infinite tamp in the form of a fluid body that surrounds the HPD and the fluid body that can also reside in the explosives shell inner volume. In this embodiment, the ends of the inner volume may be open to the fluid body as the entire HPD is underwater.
[0048] FIG. 3 illustrates four HPDs daisy chained together using connectors that couple adjacent HPDs to each other. The detonator in this example is capping into the right-most HPD. For a more uniform jet, multiple instant shock tube non-electric detonators can be capped into each of the HPDs and fired simultaneously in a multi-point configuration.
[0049] FIG. 4 illustrates end (left panel) and center (right panel) initiation with resultant explosive detonation and corresponding liquid jet particle vector lines. There is a distance before the reaction is steady state. As such, the detonation velocity and thus the shock velocity in the water is slower nearer the initiation point. The projection angle for particle velocity is known as the Taylor projection angle and is provided by . The dashed lines show the direction of particle velocity and the length is proportional to velocity.
[0050] FIG. 5 illustrates that at a critical radius r, the curvature is such that the water will flow in one direction and toward the target.
[0051] FIG. 6 is different views of a mass focusing shaped charge that is an HPD with a curvature defined by the critical radius and positioned to cut the bomb along a portion of the bomb's longitudinal axis. The optimum curvature results in greater penetration. In this example, the bomb is underwater, and the explosives shell inner volume is flooded with the water surrounding the HPD and target.
[0052] FIG. 7 illustrates the shaped charge in a configuration to disrupt a dry land-based target by inserting the HPD shaped charge into container filled with a fluid body, such as water. In this example, a FLEXCAT container is used.
[0053] FIG. 8 illustrates the mass focusing shaped charge with a plurality of layers of SMART material. A strip of high-density rubber acts as a jet clipper to reduce shocks when the jet impacts the bomb. In this example, only the left most priming channel is filled with explosives. A booster of layered sheet explosives is adjacent to the blasting cap.
[0054] FIG. 9 is an embodiment having a SMART material of closed cell foam filling a plastic box (SMART box) which has coupling grooves to receive tabs on the explosives shell. The explosives shell is slid into position over the SMART box. A set screw locks the detonator after it is inserted through the tube. The end of the detonator is pressed against the priming channel booster of explosives that passes through the explosives shell and connects to the main charge (conformable layer of explosives).
[0055] FIG. 10 is a mass focusing shaped charge that is specially configured for use with divers. For example, buoyancy control plates are connected to the shaped charge, such as inserted into pockets, to make the shaped charge neutrally buoyant. A tow line attachment point and detonator lead strain relief anchor prevent the detonator from pulling free while the diver is in transit to the target. The wire leads or shock tube lead can be lased through the two small holes. The lead is attached to a main line that extends above the water so the HPD can be fired on land or from a boat. In this example, the SMART surface facing the inner volume of fluid has a parabolic curvature to reduce the effects of the rarefaction waves, aid in jet formation, and increase the jet tip velocity.
[0056] FIG. 11 illustrates a firing train guide that saddles the explosives shell with priming channels that are filled with strips of sheet explosives to propagate a detonation wave in both directions from the base of the detonator at the center of the shaped charge. The explosive strip may run along the apex and branches at both ends. Four of the priming channels are filled with explosives to simultaneously initiate at four points symmetrically positioned on the explosive surface, for example, simultaneously initiate the main sheet explosive charge near its four corners.
[0057] FIG. 12A contains various views of a parabolic explosives shell having an explosives firing train guide straddling the explosive shell. FIG. 12B is an exploded view to better illustrate a SMART tamp placed between the former of the explosive shell and the firing train guide to prevent shock coupling with the main charge through the material and premature initiation of the main charge at an undesirable location. For clarity, explosives are not shown.
[0058] FIG. 13A illustrates a steel or metal explosive former sandwiched between two layers of sheet explosives. The outer layer of explosives generates forces that oppose the inner layer of explosives which has the primary function of imploding the fluid. FIG. 13B is the assembled configuration with different views.
[0059] FIG. 14: For land-based operations, the multilayered explosive former design is compact. The only fluid required is the inner volume of fluid which fills the volume of a closed container having a surface that conforms to the explosive forming shell.
[0060] FIG. 15 is an embodiment of a mass focusing shaped charge with a SMART box configured to contain a SMART material, that also illustrates the distal surface can be curved for more intimate contact to a target surface.
[0061] FIG. 16 illustrates a SMART material operably connected to an outer distal surface of the container. The SMART material is in an opposable configuration to the shaped charge (HPD) with the HPD operably connected to the inside face of the container so that the container distal surface is effectively sandwiched between the HPD and the SMART material.
[0062] FIG. 17 illustrates use of a structural support to reliably position the shaped charge (HPD) inside a container.
[0063] FIGS. 18A (front view) and 18B (side view) show a shaped charge used to disable a buried target, such as a mine by use with a stand that supports and positions the shaped charge.
[0064] FIGS. 19A (front view) and 19B (side view) illustrates use of a stand for disrupting a target that is partially buried.
[0065] FIG. 20 is a sectioned view of a more classical embodiment of a mass focusing shaped charge configured to form a linear metal jet from a metal liner, such as copper or steel.
[0066] FIG. 21 illustrates the mass focusing shaped charge of FIG. 20 during a jet formation event. The jet is formed from a mass of the metal liner and is illustrated traversing an air gap (stand-off distance between the shaped charge and the ground) and an Earth gap (penetrating depth d) toward a target that is a buried mine.
DETAILED DESCRIPTION
[0067] The terms IED hazardous device, bomb, and ordnance are used interchangeably herein and are more generally referred herein as a target.
[0068] 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.
[0069] 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.
[0070] 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 (FIG. 1). An added benefit of these materials is their shock Hugoniot properties such as density and bulk speed of sound which makes them better tamping materials than water. Adding thickness to them enhances explosive tamping. For example, schedule 80 black pipe has a wall thickness of approximately 0.22 and for comparison, schedule 40 pipe has a wall thickness of approximately 0.15. The reason steel and other metals are not used in mass focusing charges is because they are a fragmentation hazard. The tamp can fragment and will be explosively accelerated to high velocities faster than most bullets. The HPDs provided herein solves this issue.
[0071] 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, FIG. 2, illustrates a mass focusing shaped charge 1 connected to a target 5, in various views, including perspective and end views. In this example, the shaped charge 1 is positioned to sever the fuze head from the main charge of target 5 that is a bomb underwater. The water environment ensures the inner volume 18 is flooded with water, and SMART material 70 is positioned between the inner volume 18 and target 5. The HPD is oriented such that the jet will section the bomb rather than cutting it lengthwise, separating the fuze head from the main charge. The advantages of using curved hemicylindrical or parabolic shapes are described below. Custom made curvatures can also be made using tubing and pipes, which are formable in a press or softened and bent. Drainage installers use a commercially available PVC heater/bender tool to adjust the curvature of drainage pipe on the job site. In a similar manner, the curvature of the explosives shell may be tailored to the corresponding curvature of the target or desired fluid jet parameters.
[0072] 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.
[0073] 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.
[0074] 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 (FIG. 3). FIG. 3 illustrates a connector 90 that snaps together. Other connectors may correspond to a sleeve that two sections slide inside and abut each other in a tight-fit configuration, an adhesive that bonds adjacent shaped charges 1 to each other, or notches/tabs on the end surfaces. In this manner, any number of shaped charges are connected to generate any of a range of jet heights tailored to the desired target disruption.
[0075] 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.
[0076] 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 (FIG. 4). The consequence for a straight HPD, or any linear mass focusing shaped charge for that matter, is the water jet height expands until the water is stretched apart because water cannot withstand tensor stress; the jet eventually atomizes. At a critical bend or curvature, the shock waves are parallel and the jet doesn't stretch at the top and bottom edge. In addition to controlling jet profile, a curved HPD is ideal to perforate a curved or cylindrical bomb geometry.
[0077] At a critical curvature defined by the radius, the water within the jet travels all in the same direction toward a target (FIG. 5). Accordingly, one embodiment is an HPD having an explosives shell sectioned profile with a critical radius r, such that the liquid in the inner volume fluid flows in one direction and toward the target upon detonation.
[0078] 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 FIG. 6 for jet formation in a wedge shape aligned with the longitudinal axis 6 of the target.
[0079] 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 (FIG. 7). Any container, including the FLExCAT disrupter can be used. The container 100 is filled with a fluid such as water. See also, as another embodiment, FIG. 14, where the inner volume fluid is contained within a container 100 that is sealed by a seal 102.
[0080] 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.
[0081] FIG. 7 illustrates container 100 and seal 102 (e.g., a removable lid) that form a container volume 101 that is configured to hold a fluid body 50 that surrounds the mass focusing shaped charge 1. The inner volume of fluid within the explosives shell 10 may be a liquid that is the same as fluid body 50 (particularly for embodiments where the top and bottom of the explosives shell are open to flood the inner volume 18 with fluid body 50) or may be different than fluid body 50, such as for embodiments where explosives shell 10 is sealed off from fluid body 50 by top and bottom shell surfaces 19. As previously described, SMART material 70 is positioned between the inner volume of fluid and the target. The container may have a surface shape 103 that is curved, including a curvature that matches the curvature of the explosives layer supported by the explosives shell surface, wherein the surface shape 103 is positioned between the shaped charge 1 and a target. For consistency, the container surface shape 103 is described as the container distal surface since it is the surface that is positioned closest to the target (see, e.g., FIG. 1 for distal (toward target) and proximal (away from target) definitions). For dry land application, there can be an air gap or standoff distance 7, between the container distal surface 103 and the target 5. The bottom graphic in FIG. 7 shows the standoff distance 7. Exemplary standoff distances 7 include between 0.25 (about 0.7 cm) to 72 (about 183 cm). The other container surfaces may be similarly curved thereby ensuring appropriate functionality irrespective of container orientation, or may be straight-lined or otherwise curved (meaning container is directionally biased so that user must take care to ensure the SMART material 70 is adjacent to the container surface shape 103.
[0082] 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.
[0083] 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 (FIG. 8). Above a critical shock pressure, the rarefaction wave will cause the water volume to vaporize into a gas bubble ruining the jet. The SMART material reduces the peak pressure of the reflected rarefaction wave.
[0084] FIG. 8 illustrates that the SMART material 70 may be formed from a plurality of SMART layers. In this example, there are five SMART layers (70a-70e). A jet clipper layer 71 may also be formed from a SMART material, such as rubber, that is different from the other SMART layers. Priming channels 131 can be filled with explosives and may be generally considered, alongside detonator 65, as part of the firing train 120 by which a well-controlled explosive initiation of conformable layer of explosives 60 occurs. This results in the inner volume of fluid 20 positioned in the shell inner volume 18 that is propelled toward a target. To facilitate connecting to a target surface, the mass focusing shaped charge may have connectors 90 on the distal surface, including a clipper layer 71, to reliably contact the shaped charge to the target. For a magnetizable target surface, the connectors may comprise magnets. Other connectors include adhesives, clips, straps, ratchet straps, and elastic bands positioned around the target and shaped charge outer surfaces. Ratcheting clip 66 may be used to secure the detonator 65 in place.
[0085] 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/ft.sup.3. 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.
[0086] Referring to FIG. 9 (third panel), it is undesirable for water to be positioned between the mass focusing shaped charge SMART 70 and the target 5. Ideally there is intimate contact between the distal surface 42 of the distal body 40 (e.g., SMART material) and the bomb container wall 6. If the target has a steel skin, magnets can be inserted into the bottom of the HPD to facilitate attachment. A tripod attachment can also be used using a -20 threaded hole in the HPD. Flexible tripods can be wrapped around anchors such as piers or pilons. There are special adhesives that work under water and coating the bottom of the HPD will foster adhesion to the targeted device. To modulate shock pressures when the jet impacts the IED, the SMART thickness can be adjusted. In FIG. 8, a SMART material that is layered by a defined thickness for a specific amount of sheet explosives and HPD size. A denser SMART material can be used at the base of the HPD to clip the jet prior to impacting the bomb. This jet clipper can be made from synthetic and natural rubbers such as silicone and gum rubber. Eroding the jet tip before impact slows it down and causes jet bunching. The impact pressures drop significantly thereby reducing risk of unwanted shock initiation of the target.
[0087] 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., FIG. 8), cut into them which allows for initiation at many points at one time and at different locations on the conformable layer of explosives 60. At the desired initiation points, the priming channels are filled with explosives to allow the detonation from the blasting cap to propagate to the main charge of sheet explosives on the opposite side of the explosive shell.
[0088] A variety of detonator attachment methods can be used. In FIG. 8, ratcheting clips 66 lock the detonator 65 (that is within the detonator tube) into position. FIG. 9 shows another embodiment that uses a detonator tube and a set screw 67 to lock the detonator in place. In both examples, the detonator is side priming the priming channel explosives and a sweeping detonation wave initiates the priming channel booster. Reliable initiation of sheet explosives can be accomplished using the side priming method. A SMART box 75 may contain the SMART material 70. Accordingly, distal body 40 may correspond to the SMART material 70 for embodiments without a SMART box (see, e.g., FIG. 8) or may be a container 75 holding the SMART material (also referred herein as a SMART box). The explosives shell 10 may slide into position over a distal body 40 having a distal body surface 42. Distal body may also be referred to as a SMART box 75. In this manner, the distal surface 42 may be in intimate contact with a target surface 6, thereby avoiding unwanted gaps between the shaped charge and the target, including a water-filled gap. To facilitate introducing a SMART material into a distal body 42, including a SMART fill box 75, an injection fill hole 77 may traverse from the outer to the inner surfaces of the distal body (FIG. 10).
[0089] A diver who is carrying a shaped charge 1 such as a HPD underwater may have to deal with water currents, and poor visibility. FIG. 10 illustrates a tow line attachment 150 attached to the shaped charge surface. The line can then be clipped onto the diver thereby securing the shaped charge to the diver. As the diver transits the water to the target, the detonator leads are being pulled on. To prevent the detonator from slipping out from excessive tension on the lead(s), a detonator lead strain relieve anchor 68 is on the opposite side from the tow line attachment 150 point. The detonator leads are connected to a main firing line or shock tube trunk line that is fed out from the firing point on land or in a boat. The bulk of the SMART material is a closed cell foam and that will cause the HPD to rapidly float to the surface. To make the shaped charge neutrally buoyant, buoyancy control plates 110, including formed of steel, lead, brass, copper, or other heavy metal plating, may be inserted into pockets on both sides of the SMART box. If the operator temporarily loses control of the HPD just after disconnecting the tow line, it will float neutrally so it can be recovered. The explosives forming shell 10 in FIGS. 9 and 10 are attached to the SMART box that has grooves near the top. Tabs on the explosives former slide into these grooves and lock the former into place. For practical loading of the sheet explosives, the explosives former is attached to the SMART box after explosives are attached to it.
[0090] 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 FIG. 11, a firing train guide saddles the explosives former. Sheet explosive strips (142) are placed in the firing train guide grooves 141. One explosive strip 142 is at the apex and oriented longitudinally. In this example, additional strips branch off at the far ends of the HPD and four of the priming channels are filled with explosives. The initiation at the detonator placed in the center of the HPD causes detonation waves to propagate towards both ends. The detonation wave then turns the corner at the branches and travels to the priming channels that are filled with explosives. The detonation is communicated through the channel and the main charge is initiated near its four corners. The detonation waves formed expand from each point and collide causing higher shock pressures in the collision zones. Overall, the explosives are more uniformly initiated. The jet has a higher velocity and is more stable. In FIG. 11, there is a gap between the firing training guide and the explosives former which prevents shock coupling and undesirable premature initiation.
[0091] Another technique to prevent undesirable initiation due to shock coupling is shown in FIGS. 12A-12B in which a SMART tamp layer 130 is placed between the explosives former 10 and the firing train guide 120. No explosives are shown in FIG. 12A-12B to aid the reader in focusing on the structural elements. FIG. 12B is an exploded view and illustrates the guide grooves 141 which position the sheet explosive strips (not shown). The sheet explosives strips may be positioned in an initiation zone 140 corresponding to a longitudinal axis at a curvature apex. As illustrated in FIG. 11, the initiation zone 140 is near the detonator.
[0092] 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 (FIG. 13A-FIG. 13B). No distal body is shown in FIG. 13A-13B. The explosives forming shell 10 is sandwiched between the layers 170 and 171 of sheet explosives. The shock properties are greatly enhanced as there is a positive shock reflection off the steel former. The second layer of explosives sends a forward moving shock through the steel that adds to the duration of loading on the water slug. The transmitted shock arrives at a layer of SMART acting as a SMART tamp 130 which attenuates it and delays the returning rarefaction wave formed at the SMART-air boundary. This further increases pressure and duration of loading on the fluid slug. FIG. 13B provides various views of the explosives shell with outer and inner shape conforming explosives and a SMART tamp.
[0093] For land-based operations, the design shown in FIG. 14 is more efficient than the conventional submersion of the explosives in a fluid filled container or placing the explosives between two fluid filled containers to form the tamp and slug. In this example, the inner volume of fluid is contained within a distal body 40 having a distal surface 42 that is curved. The distal body 40 corresponds to a sealable container 100 having a seal 102 that occupies inner volume 18. The volume of the charge is vastly reduced and due to its efficiency, less tamp material is required; there is a reduction in total weight. The mass focusing disrupter is compact making it suitable for dismounted and tactical operations. This embodiment may be used in SWAT explosive breaching operations to breach doors or walls, or to create gun or viewing ports. Over pressure is reduced by the SMART material which also makes it applicable for operations inside of dwellings and interior structures. Curvature can be added to the distal surface of the inner fluid container to further improve jetting properties of the disrupter.
[0094] FIG. 15 is an additional embodiment of a mass focusing shaped charge, including a SMART box with detonator lead strain relief anchor, tow line attachment point and a curved distal surface. The curved distal surface 181 allows for more intimate contact to a target surface. In this manner, the distal surface may of the shaped charge may be shaped to correspond to a target surface to facilitate intimate contact that minimizes water between the shaped charge distal surface and the target.
[0095] In other embodiments, including as exemplified in FIGS. 16-19, the mass focusing shaped charge is configured to provide disablement capability through, at least in part, the ground. This has applications related to a target that is at least partially or completely buried ordnance, including unexploded ordnance from previous conflicts. For example, any of the mass focusing shaped charges described herein may be connected to a stand to reliably position the direction of a resultant explosively-driven fluid used to disable the target.
[0096] FIG. 16 illustrates mass focusing shaped charge 1 in a container 100, with the container set a standoff distance 7 from a target 5. A smart material 300 is connected to an outer facing surface of container distal surface 104. The shaped charge 1 is connected to an inner facing surface of container distal surface 104, wherein the inner and outer facing surfaces are separated by the container distal wall thickness 106. In this manner, the SMART material 300 can be characterized in an opposable configuration relative to the shaped charge 1. The container 100 has a fluid-filled container volume 101. A detonator 65 with detonator lead wires provide controlled detonation of shape charge 1, with the SMART material 300 configured to ensure good fluid jet characteristics as fluid jet is explosively driven from the container volume toward the target. In this manner, the shaped charge described herein may be used to traverse a stand-off distance through air. The container 100 may have a container seal 102 corresponding to a lid for positioning of shaped charge 1 and/or filling of container volume 101 with liquid, such as water. Use of a SMART material component on the front distal surface provides the benefit of helping to facilitate maintenance of fluid jet characteristics as the fluid jet travels toward target 7, including by avoiding degrading effects otherwise caused by rarefaction waves after explosive detonation. Use of a SMART material that is buoyant (e.g., lower density relative to the liquid in the container) is facilitated by mounting the SMART material to an outer surface of the container distal surface.
[0097] FIG. 17 illustrates use of a structural support 310 to reliably positioned the shaped charge 1 in a container 100 for three different views. In this example, the structural support is in contact with a proximal surface of the container 100 and the half pipe disrupter (HPD) 1. It braces the HPD 1 up against the container distal surface 104 (see, e.g., FIG. 16), restricting unwanted shaped charge (HPD) movement and reliably fixing into a desired position inside the fluid filled container 100. In this example, the container distal surface 104 has a curved geometry. The invention is, of course, compatible with other structural supports beyond the brace of FIG. 17. For example, an adhesive, such as glue, can be used to bond the HPD 1 to the distal surface 104 of the container 100, thereby fixing shaped charge HPD 1 into position. In this configuration, the explosives forming shell can be separate from the SMART box which could be glued inside the container. The explosives forming shell can then be loaded with sheet explosives and then seated to the SMART box. The structural support 310 may be made of a material that matches a property of the fluid in the container. For example, for a water-filled container, the structural support may be formed from PVC having a higher density than water or of another material that matches the density of water.
[0098] FIGS. 18A-18B illustrate an embodiment where the fluid jet can penetrate the Earth (e.g., soil or sand) and disable a buried target 5, such as a mine. A flexible stand 320 positions the disrupter leveling it on uneven ground and setting a standoff distance. The stand can be made from plastic, or metal such as steel or aluminum. A non-magnetic material can be used if there is concern regarding use of a metal detection sensor in the mine.
[0099] FIGS. 19A-19B, are similar to FIGS. 18A-18B, but with a target 5 that is a partially buried aerial bomb. Using a flexible stand 320, the HPD can be positioned over an explosive remnant of war, such as an aerial bomb. The stand keeps the HPD from making direct contact with the bomb and can level it and position the HPD at a specific location so that the fluid jet ruptures and/or deforms the bomb casing, resulting in safe disruption without uncontrolled target explosion.
[0100] The examples provided in FIGS. 18A-19B may also use a metal liner, such as copper or steel having a thickness between about 0.0625 inches-0.125 that form a portion of the distal body 40 (along with SMART material 300). In this aspect, the HPD has characteristics similar to a classical shaped charge, such as no intervening fluid volume 20 as illustrated in FIG. 14. This HPD mass focusing shaped charge embodiment that effectively jets a blade of plastically formed metal is further illustrated in FIGS. 20-21. In this embodiment, the HPD is configured so that upon explosive detonation by detonator a linear metal jet is formed. Typical metals useful in the invention include, but are not limited to, copper or steel. The jet profile is a blade of plastically formed metal. The implosion pressure is high and exceeds the Huguenot Elastic Limit (HEL) of the metal liner of thickness y. Above the HEL a metal will behave hydrodynamically. The metal is crushed and flows outward at high velocities. Because this is a more classical shaped charge, the jet penetration is defined by the ideal penetration equation. Using the classical shaped charge embodiment, the HPD jet can cut through steel, armor, and earth (soil or sand). This embodiment preferably has two SMART components, such as a first SMART material supported by the outer surface of the explosives shell (labeled in FIG. 20 as a rubber), and a second SMART material that is supported by the metal liner (labeled in FIG. 20 as a foam). The second SMART material may occupy the inner volume and is selected to provide desired jet characteristics for the metal of the metal liner that jets toward target depending on the application (e.g., stand-off distances, target type, metal composition, explosives composition and configuration, operating conditions etc.).
