Low standoff shaped charge

Abstract

An explosive device includes an explosive material and a liner. The explosive material includes a void, and the liner is adjacent to a surface of the explosive material in the void. The void has a center axis with a base at a first end of the center axis, a terminal end at a second end of the center axis opposite the first end, and a sidewall therebetween wherein the sidewall has an inflection portion with an angle between 30°and 60°with the center axis.WO

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 425,584 , filed on Nov. 15, 2022, which is hereby incorporated by reference in its entirety.BACKGROUNDBackground and Relevant Art

[0002] Shaped charges are used to direct the energy of an explosion to penetrate a surface. Conventional shaped charges accelerate a liner material in a jet, and the liner material assists in penetrating the target with a standoff distance. The standoff distance provides a conventional shaped charge time to form the jet or slug of liner material.BRIEF SUMMARY

[0003] In some embodiments, an explosive device includes an explosive material and a liner. The explosive material includes a void, and the liner is adjacent to a surface of the explosive material in the void. The void has a center axis with a base at a first end of the center axis, a terminal end at a second end of the center axis opposite the first end, and a sidewall therebetween wherein the sidewall has an inflection portion with an angle between 30° and 60° with the center axis.

[0004] In some embodiments, an explosive device includes a housing, an explosive material radially within the housing, and a liner. The explosive material includes a void, and the liner is adjacent to a surface of the explosive material in the void. The void has a center axis with a base at a first end of the center axis, a terminal end at a second end of the center axis opposite the first end, and a sidewall therebetween wherein the sidewall has an inflection portion with an angle between 30° and 60° with the center axis.

[0005] In some embodiments, an explosive device includes a shaped charge and an unmanned aerial vehicle (UAV). The shaped charge includes a housing, an explosive material radially within the housing, and a liner. The explosive material includes a void, and the liner is adjacent to a surface of the explosive material in the void. The void has a center axis with a base at a first end of the center axis, a terminal end at a second end of the center axis opposite the first end, and a sidewall therebetween wherein the sidewall has an inflection portion with an angle between 30° and 60° with the center axis. The UAV is configured to carry the shaped charge with the terminal end at or below a skid of the UAV.

[0006] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0007] Additional features and advantages will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the teachings herein. Features and advantages of the disclosure may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Features of the present disclosure will become more fully apparent from the following description and appended claims or may be learned by the practice of the disclosure as set forth hereinafter.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to describe the manner in which the above-recited and other features of the disclosure can be obtained, a more particular description will be rendered by reference to specific implementations thereof which are illustrated in the appended drawings. For better understanding, the like elements have been designated by like reference numbers throughout the various accompanying figures. While some of the drawings may be schematic or exaggerated representations of concepts, at least some of the drawings may be drawn to scale. Understanding that the drawings depict some example implementations, the implementations will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0009] FIG. 1-1 is a side cross-sectional view of a shaped charge, according to at least some embodiments of the present disclosure;

[0010] FIG. 1-2 is a side cross-sectional view of the shaped charge of FIG. 1-1 during detonation, according to at least some embodiments of the present disclosure;

[0011] FIG. 2-1 is a side cross-sectional view of another shaped charge, according to at least some embodiments of the present disclosure;

[0012] FIG. 2-2 is a side cross-sectional view of another shaped charge with a flat base, according to at least some embodiments of the present disclosure;

[0013] FIG. 3 is a side cross-sectional view of a shaped charge puncturing a target material, according to at least some embodiments of the present disclosure;

[0014] FIG. 4 is a schematic representation of a shaped charge perforating a well casing, according to at least some embodiments of the present disclosure;

[0015] FIG. 5 is a schematic representation of a shaped charge used for avalanche control, according to at least some embodiments of the present disclosure;

[0016] FIG. 6 is a side view of a shaped charge carried by an unmanned aerial vehicle, according to at least some embodiments of the present disclosure;

[0017] FIG. 7-1 is a perspective exploded view of a two-part housing for a shaped charge, according to at least some embodiments of the present disclosure; and

[0018] FIG. 7-2 is a side cross-sectional view of the two-part housing of FIG. 7-2.DETAILED DESCRIPTION

[0019] The present disclosure relates to explosive devices. More particularly, the present disclosure relates to explosive devices that provide directed energy. For example, a shaped charge according to the present disclosure includes an explosive material positioned on a first side of a liner. The explosion, upon detonation, applies energy to the liner to accelerate the liner away from the explosion. In some embodiments, the liner is substantially conical with the explosive material positioned outside of the cone formed by the liner.

[0020] In a conventional explosive device, explosive energy is released directly away from (e.g., normal to) the surface of the explosive material. In some embodiments, modifying the surface geometry of the explosive material with a void therein concentrates the explosive energy in the void. For example, when the hollow is shaped with a cone, a hemisphere or another recess that reduces in cross-sectional area, the pressure generated by the detonation of the explosive material urges at least a portion of the liner into the recess. The liner, thereby, compresses and / or collapses inward toward a center axis of the void. The pressure of the explosive material may form and / or project a high-velocity jet of liner material away from the void, substantially in the direction of the center axis of the void. In some embodiments, a majority of the jet material originates from the innermost part of the liner.

[0021] In some embodiments, a shaped charge according to the present disclosure includes a void and liner with a geometry that allows the shaped charge to form a jet with substantially no standoff. In some embodiments, the shaped charge has a pressure focus that is located substantially at the terminal end of the liner. By focusing the pressure and / or jet material accelerated by the pressure at the terminal end of the liner, the shaped charge may be smaller, and the shaped charge may be detonated more safely relative to a conventional shaped charge with a standoff.

[0022] A shaped charge according to the present disclosure has a shape to the void of the explosive material and the associated liner that allows for substantially no standoff before the jet is formed. In some embodiments, the liner has a uniform thickness across a surface of the explosive material adjacent the void such that the shape of the exterior surface of the liner (e.g., in the void) is the same as the exterior shape of the explosive material proximate the void. In other embodiments, the liner has a non-uniform thickness, and the shape of the exterior surface of the liner is different from the exterior shape of the explosive material proximate the void.

[0023] In some embodiments, the surface of the explosive material proximate the void of the shaped charge defines a rounded concave base (being axially opposite the open end of the void, where the jet is directed out the open end) in contrast to a conventional conical base. At least a portion of the base may be semi-circular with a constant radius of curvature. In other examples, at least a portion of the base may be parabolic. The concave base, in some embodiments, contacts a convex portion of the sidewall of the void, wherein the sidewalls of the void curve away from the center axis in the direction of the jet. In some embodiments, the sidewalls may form an angle with the center axis between 30° and 60° at the inflection point between the concave portion and the convex portion. The inflection point is where the convex portion of the sidewall and the concave portion of the sidewall meet. In other word, the inflection point is where the sidewall changes from the concave to convex. In some embodiments, the inflection point is an inflection portion that is linear for at least part of the sidewall between the concave portion and the convex portion. In some embodiments, the void has a concave base and a linear sidewall. In some embodiments, the void has a concave base that is continuously concave from the end of the base to the opposing open terminal end of the void.

[0024] By shaping a void of the explosive material, and the liner adjacent to the surface of the explosive material, according to some embodiments of the present disclosure, the shaped charge does not need a standoff. The standoff, in a conventional shaped charge, allows the jet (and slug) to form from the liner past the terminal end of the void and / or the shaped charge. The jet, therefore, has more time to accelerate, but requires more distance from the object targeted by the directed energy. For example, a conventional standoff can be as high as 2 meters. While a standoff can increase the penetration capability of a shaped charge, if the jet has insufficient space to form, the shaped charge can fail to achieve the intended penetration into the target surface. In contrast, a shaped charge according to the present disclosure that does not require a standoff can be used in smaller spaces than a conventional shaped charge and / or use a larger mass of explosive material in the available space. For example, shaped charges can be used in drilling and mining applications to penetrate wellbore casing. The shaped charge is oriented perpendicular to a longitudinal axis of the wellbore to direct the jet of the shaped charge toward the wellbore casing and penetrate the wellbore casing. A shaped charge according to the present disclosure can be used in a smaller wellbore than a conventional shaped charge and / or use a larger mass of explosive material in the limited space in the wellbore.

[0025] FIG. 1-1 is a side cross-sectional view of a shaped charge 100, according to some embodiments of the present disclosure. The shaped charge 100 has an explosive material 102 with a void 104. The void 104 has a center axis 106 between a base 108 of the void 104 and a terminal end 110 of the void 104. The terminal end 110 is open and directs the jet from the shaped charge 100 in the direction of the center axis 106. A liner 112 is positioned adjacent the explosive material 102 in the void 104.

[0026] In some embodiments, the liner 112 includes or is made of glass. For example, the glass may be a silicate glass containing silicon dioxide. In some examples, the glass is substantially all silicon dioxide, while in other examples, the glass contains silicon, oxygen, and other elements, such as a borosilicate glass, soda-lime glass, or lead crystal glass. In some embodiments, the liner 112 includes or is made of metal, such as copper, aluminum, magnesium, tungsten, iron, titanium, vanadium, chromium, lead, tin, cadmium, cobalt, and alloys or combinations thereof. In some embodiments, the liner 112 includes environmentally benign materials, such as glass, aluminum, or iron, that do not contaminate groundwater or surface water. In some embodiments, the liner 112 includes inert materials that are not reactive with water or oxygen in the atmosphere. In some embodiments, the liner 112 includes biodegradable materials that break down over a period of less than 10 years when exposed to outdoor weather and environmental elements. Environmentally benign materials in the liner 112 may allow a shaped charge 100 according to the present disclosure to be used in underground applications (such as drilling or mining) or in aboveground applications, such as avalanche control, in sensitive or protected locations such as United State Forest Service lands.

[0027] The shaped charge 100 has a housing 114 positioned radially around the explosive material 102 relative to the center axis 106. For example, the housing 114 may be substantially cylindrical and the explosive material 102 is positioned radially within the housing relative to the center axis 106. In some embodiments, the housing 114 is integrally formed with the liner 112, such that the liner 112 and housing 114 are a continuous piece of material. In some embodiments, the housing 114 is separate from the liner 112. For example, the housing 114 and the liner 112 may be separate pieces that are bonded, adhered, or otherwise affixed to one another. In some embodiments, the shaped charge 100 is a linear shaped charge with a transverse cross-section as described and / or illustrated herein.

[0028] In some embodiments, the housing 114 has a tensile strength that is greater than a tensile strength of the liner 112. In some examples, the housing 114 includes or is made of a housing material that has a greater tensile strength than a liner material of the liner 112. In some examples, the housing material and the liner material are the same material, and the housing 114 has a thickness in the radial direction that is greater than a thickness of the liner 112. The bulk tensile strength of the housing 114 may, therefore, be greater than the bulk tensile strength of the liner 112 even when the housing 114 and liner 112 are the same material. By confining the explosive pressure, the housing 114 can increase the proportion of the energy accelerating the liner 112 and / or jet. In some embodiments, the housing material is made or and / or includes steel, aluminum, glass, biodegradable materials, environmentally benign materials, plastics, or combinations thereof. In at least one embodiment, the housing material includes stainless steel. In at least one embodiment, the housing material includes polyetheretherketone.

[0029] In some embodiments, the profile of the void 104 and / or the liner 112 adjacent to the void 104 at least partially causes the explosive pressure of the shaped charge 100 to have a focal point substantially at the terminal end 110. In some embodiments, the profile of the void 104 and / or the liner 112 adjacent to the void 104 at least partially causes the explosive pressure of the shaped charge 100 to have a focal point proximate the terminal end 110 such that the shaped charge 100 has substantially no standoff. For example, the shaped charge 100 may be intended to penetrate a wellbore casing 4 centimeters (cm) thick, and the focal point of the explosive pressure may be approximately 2 cm past the terminal end 110. The focal point of the explosive pressure may, therefore, be within the target surface (e.g., the wellbore casing) to penetrate the target surface without a standoff.

[0030] In some embodiments, a focal point of shaped charge 100 is positioned along the center axis 106. In some embodiments, the shaped charge 100 has a plurality of focal points and / or a line of focus along the center axis 106. For example, the shape of the void 104 and / or liner 112 adjacent to the surface of the void 104 may direct the explosive energy toward an elongated region of the center axis 106. In some embodiments, the curvature of the surface of the void 104 provides plurality of focal points and / or a line of focus along the center axis 106. For example, a concave portion 118 of a sidewall 116 of the void 104 (relative to the center axis 106) may focus the explosive energy to a focal point. In some examples, a linear portion 120 of the sidewall 116 of the void the focuses the explosive energy along a focal line of the center axis 106. In yet other examples, a convex portion 122 of the sidewall 116 of the void 104 focuses the explosive energy along a longer focal line of the center axis 106 than the linear portion 120. In at least one example, the void 104 is rotationally symmetrical around the center axis 106. For example, the void 104 may be substantially uniform relative to the center axis 106 as the shaped charge 100 is rotated around the center axis 106.

[0031] In some embodiments, the sidewall 116 forms an angle with the center axis 106 between 30° and 60° at the inflection point between the concave portion 118 and the convex portion 122. The inflection point is where the convex portion 122 of the sidewall and the concave portion 118 of the sidewall 116 meet. In other word, the inflection point is where the sidewall changes from concave to convex. In some embodiments, the inflection point is an inflection portion that is a linear portion 120 for at least part of the sidewall between the concave portion and the convex portion.

[0032] The explosive material 102 can be made of or include one or more high explosives. For example, the explosive material 102 has a relative effectiveness (RE) factor or TNT equivalence of greater than 1.0. In at least one example, the explosive material 102 has an RE factor greater than 1.5. In some embodiments, the explosive material is or includes C-3, C-4, Pentolite, Semtex, Hydrazine mononitrate, Nitroglycerin, Hexogen, Trinitro azetidine, or other high and low explosives. In a particular example during testing, a shaped charge 100 with a glass liner 112, a glass housing 114, and nitroglycerin explosive material 102 according to the geometry described herein penetrated a two-inch thick piece of ballistic steel without a standoff.

[0033] FIG. 1-2 illustrates the shaped charge 100 described in relation to FIG. 1-1 during detonation. In some embodiments, the focal point 124 of the detonation is substantially at the terminal end 110. In some embodiments, the focal point 124 is past the terminal end 110 by a focal length 125 that is relative to a void length 126 of the void 104 measured from the base 108 to the terminal end 110. In some embodiments, the focal length 125 is no more than 100% of the void length 126. For example, in a void length 126 of 6 cm, the focal length 125 may be no more than 6 cm. In some embodiments, the focal length 125 is no more than 50% of the void length 126. For example, in a void length 126 of 6 cm, the focal length 125 may be no more than 3 cm. In some embodiments, the focal length 125 is no more than 33% of the void length 126. For example, in a void length 126 of 6 cm, the focal length 125 may be no more than 2 cm.

[0034] As described herein, the focal point 124 may be a linear region and not a single point. In such embodiments, the focal point has an axial length of no more than 2 cm. In some embodiments, the focal point has an axial length of no more than 1 cm. In some embodiments, the focal point has an axial length of no more than 0.5 cm. In some embodiments, the volume which defines the focal point is any region that exhibits at least 80% of the explosive energy relative to the peak explosive energy.

[0035] Some embodiments of a shaped charge according to the present disclosure have a linear portion of the sidewall, such as described in relation to FIG. 1-1. Referring now to FIG. 2-1, in some embodiments, a shaped charge 200 has a plurality of linear portions 220-1, 220-2 of the sidewall 216 that direct the explosive energy at different focal points. In some embodiments, the first linear portion 220-1 has a first angle 228-1 relative to the center axis 206 and the second linear portion 220-2 has a second angle 228-2 relative to the center axis 206. For example, the first angle 228-1 may be greater than the second angle 228-2. In some examples, the first angle 228-1 may be less than the second angle 228-2.

[0036] The curvature and / or geometry of the void 204, as well as the materials of the liner 212, the explosive material 202, the housing 214, or combinations thereof affect a shockwave pattern and direction the spall from the liner 212 moves. In some embodiments, the shockwave of the shaped charge directs the spall outward after the focal point / region, in contrast to the slug or jet of liner material of a conventional shaped charge. In at least one embodiment, a radially outward spall disperses the energy and limits damage to objects beyond the focal length of the shaped charge.

[0037] FIG. 2-2 illustrates another embodiment of a shaped charge 200 with a void 204. The void 204 has a substantially flat base 208 with a diameter 209 (or width, in the case of a linear charge). In some embodiments, the base diameter 209 is at least partially related to the void length 226. For example, the base diameter 209 may be greater than or equal to 10% of the void length 226. For example, the base diameter 209 may be greater than or equal to 30% of the void length 226. For example, the base diameter 209 may be greater than or equal to 50% of the void length 226. In a particular example, the base diameter 209 is approximately 3 cm and the void length 226 is approximately 6 cm.

[0038] In some embodiments, the flat base 208 is flat to within 10% across the base diameter 209. In some embodiments, the flat base 208 is flat to within 5% across the base diameter 209. In some embodiments, the flat base 208 is flat to within 1% across the base diameter 209. During testing, the size of the base diameter 209 affects the size and shape of the spall created after detonation.

[0039] In some embodiments, the contact surface width 211 of the shaped charge 200 proximate the terminal end 210 of the void 204 affects the size and shape of the spall created after detonation. In some embodiments, the contact surface width 211 is no less than 10% of the void length 226. In some embodiments, the contact surface width 211 is no less than 20% of the void length 226. In some embodiments, the contact surface width 211 is no less than 30% of the void length 226. In a particular example, the contact surface width 211 is approximately 1 cm and the void length 226 is approximately 6 cm.

[0040] FIG. 3 is an illustration of an embodiment of a shockwave 330 and spall 332 emitted from a shaped charge 300 (illustrated as configured prior to detonation for reference). In some embodiments, the shaped charge 300 directs liner material from the liner 312 (shown in-place prior to detonation) toward a target material 334, and the liner material penetrates the target material 334 before moving radially outward away from the center axis 306. In some embodiments, the liner material forms a ring of spall 332 (shown after detonation) that expands outward in fragments of the liner material to disperse the energy. During testing, a shaped charge 300 according to the present disclosure directed liner material through a target material 334 containing 2-inch-thick steel with no standoff, and the spall 332 formed a radially outwardly expanding ring moving approximately 45° from the center axis 306. This dispersed the explosive energy and limited damage to objects on the opposite side of the target material 334.

[0041] In some embodiments, the spall 332 moves in a direction having a spall angle 336 relative to the center axis 306 that is in a range having an upper value, a lower value, or upper and lower values including any of 15°, 20°, 30°, 45°, 60°, 70°, 75°, or any values therebetween. For example, the spall angle 336 may be between 15° and 75°. In some examples, the spall angle 336 may be between 30° and 60°. In some examples, the spall angle 336 may be greater than 15°. In some examples, the spall angle 336 may be less than 75°. In at least one example, the spall angle 336 may be substantially 45°. The size of the spall, in some embodiments, is in a range of microscopic (e.g., less than 100 microns) to spall 332 having a diameter greater than 10 cm. In some embodiments, the spall 332 is spherical. In some embodiments, the spall 332 is an annular ring around the longitudinal axis, such as produced in the initial testing and illustrated in FIG. 3.

[0042] A shaped charge requiring little or no standoff according to the present disclosure may allow for unique applications in various industries. FIG. 4 is a schematic representation of a use of the shaped charge 400 to puncture a well casing 438 in a downhole drilling or mining environment. In some embodiments, the short or zero standoff of the shaped charge 400 allows a larger mass of explosive material 402 to be positioned in the small space of the wellbore 440 relative to a conventional shaped charge. The shaped charge 400 may be positioned close to the well casing 438 to puncture the well casing 438 and allow fluids to flow between the wellbore 440 and the surrounding formation 442. In some cases, it is desirable to limit the introduction of liner material, uncombusted explosive material 402, or combusted waste products of the explosive material 402 into the formation 442 outside the wellbore 440. The broad dispersion of the spall 432 associated with the short or no standoff, limits the penetration of the liner material and explosive material into the formation 442. In some embodiments, environmentally benign liner materials, such as glass, can further limit the environmental (e.g., groundwater) effects of the shaped charge 400 and well casing 438 perforating.

[0043] FIG. 5 illustrates another example application of shaped charge 500 according to the present disclosure. Avalanche control and mass wasting (e.g., landslide, rockslide, mudslide) control is conventionally performed with non-directed explosive devices. Non-directed explosive devices are inefficient and can project debris far from the intended target material. A conventional shaped charge may penetrate the snowpack, rock, or dirt with a jet or slug of material, but a focused application of explosive force may be inefficient at dislodging material from the slope.

[0044] A shaped charge 500 according to the present disclosure directs the explosive energy toward the slope 544, limiting the projection of debris (both from the shaped charge 500 and from the slope material). In contrast to a conventional shaped charge however, the rapid dispersion of the shockwave 530 through the slope material can apply the directed explosive energy across a larger surface area or volume. The broader application of the explosive energy is similar to a conventional non-directed explosive device while remaining more efficient due the direction of the energy through the shaped charge 500. The broader application of the explosive energy through a shaped charge 500 according to the present disclosure can thereby limit the projection of debris while providing sufficient energy to the slope material to trigger a controlled avalanche on the slope 544 over a foundation material 545 (such as rock) or other mass wasting event. In some embodiments, environmentally benign liner materials or housing materials, such as glass, can further limit the environmental effects of the shaped charge 500 in sensitive locations where plastic debris or heavy metals can cause lasting damage. Additionally, glass and similar materials dissipate heat very rapidly and mitigate the risk of igniting flammable and explosive materials that might be close to or used right after.

[0045] In some embodiments, a shaped charge according to the present disclosure can be delivered or positioned to the target material by an unmanned aerial vehicle (UAV) such as a multi-rotor device (e.g., a quad-copter drone). FIG. 6 illustrates a shaped charge 600 carried by a UAV 646. In some embodiments, the compact design of the shaped charge 600 allows the shaped charge 600 to be carried by and / or fit inside the chassis of the UAV 646. In some embodiments, the directed explosive energy of the shaped charge 600 allows a smaller mass of explosive material to be used relative to a conventional non-directed explosive device, making control and flight of the UAV 646 easier. In some embodiments, the directed explosive energy of the shaped charge 600 allows the same mass of explosive material to be used as a non-directed explosive device but with greater effect.

[0046] A conventional shaped charge with a standoff requires precision control, flight, or hovering of the UAV 646 above a target material 634 to efficiently deliver the jet of liner material and explosive energy to the target material 634. Alternatively, a conventional shaped charge may include a standoff frame that contacts the target material 634 and holds the shaped charge at or near the intended standoff. However, an additional standoff frame adds mass to the device, further limiting the amount of explosive material available in the payload of the UAV 646. A shaped charge 600 according to the present disclosure operates with little or no standoff, allowing the UAV 646 to land directly on the target material 634 and / or place the shaped charge 600 directly on the target material 634 prior to detonation. In some embodiments, the terminal end 610 of the shaped charge 600 contacts the surface of the target material 634 before a strut or skid 648 of the UAV 646 contacts the target material 634. In some embodiments, the UAV 646 is configured to release the shaped charge 600 to rest on the target material 634. For example, the UAV 646 may have an electronically actuated release mechanism to release the shaped charge 600. In another example, the UAV 646 may have a switch or lever that is actuated upon contacting the target material 634 to release the shaped charge. In some embodiments, the UAV 646 is consumed upon detonation of the shaped charge 600. Some embodiments of shaped charges 600 described herein can provide a more efficient and more effective explosive energy to a target material via a UAV 646 than either a conventional shaped charge or a conventional non-directed explosive device.

[0047] FIG. 7-1 is a perspective exploded view of an embodiment of a shaped charge 700 including a housing 714. The housing 714 may include any explosive material described herein. In some embodiments, the housing 714 is integrally formed with a liner 712. The housing 714, in some embodiments, include a bottom portion 748 and a top portion 750 that are selectively connectable at a connection mechanism 752. In some embodiments, the connection mechanism 752 is a twist-lock connection that mates the bottom portion 748 and the top portion 750 without any additional fasteners, such as clips, clamps, threaded bolts, nuts, adhesives, etc. In some embodiments, connection mechanism 752 is a combination of connection mechanisms, such as a twist-lock interface and threaded bolts. In some embodiments, the top portion 748 includes a threaded interface and the bottom portion 750 includes a complementarily threaded interface to form a first part of the connection mechanism. Upon threading the threaded interfaces together, the connection mechanism 752 may further include set screws, pins, threaded rods, etc. to prevent relative rotation of the threaded interfaces.

[0048] In some embodiments, an explosive material is positioned in the bottom portion 748 and the top portion 750 is subsequently affixed thereto. In some embodiments, the top portion 750 is permanently affixed to the bottom portion, such as by welding or brazing of the top portion 750 to the bottom portion 748. As the housing is consumable during the explosion of the shaped charge 700, the bottom portion 748 and top portion 750 may be selectively connectable or permanently connectable by the connection mechanism 752.

[0049] FIG. 7-2 is a side cross-sectional view of the shaped charge 700. The housing 714 and liner 712 are, in some embodiments, integrally formed from a single liner and / or housing material. In some embodiments, the bottom portion 748 defines the void 704. In some embodiments, the top portion 750 includes an opening 754 that provides access to the interior volume of the housing 714 and / or the explosive material therein. In some embodiments, the opening 754 is part of an extended neck 756 that protrudes from the top portion 750 and away from the bottom portion 748. For example, the extended neck 756 may allow the housing 714 to be further filled with additional explosive material and / or allow positioning of a detonator (e.g., blasting cap) in the top portion 750. In some embodiments, the opening 754 is recessed in the top portion 750 toward the bottom portion 748. For example, a recessed opening 754 may simplify filling of the housing 714 with explosive material by providing an integrated funnel into the top portion 750 of the housing 714.

[0050] In some embodiments, a two-part housing 714, such as described in relation to FIG. 7-1 and 7-2 includes a liner 712 with any geometry described herein, such as in relation to FIG. 1-1 through 2-2. In at least some embodiments, shaped charges 700 according to the present disclosure can provide safer handling, positioning, and directing of explosive material compared to conventional devices.INDUSTRIAL APPLICABILITY

[0051] The present disclosure relates generally to explosive devices. More particularly, the present disclosure relates to explosive devices that provide directed energy. For example, a shaped charge according to the present disclosure includes an explosive material positioned on a first side of a liner. The explosion, upon detonation, applies energy to the liner to accelerate the liner away from the explosion. In some embodiments, the liner is substantially conical with the explosive material positioned outside of the cone formed by the liner.

[0052] In a conventional explosive device, explosive energy is released directly away from (e.g., normal to) the surface of the explosive material. In some embodiments, modifying the surface geometry of the explosive material with a void therein concentrates the explosive energy in the void. For example, when the hollow is shaped with a cone, a hemisphere or another recess that reduces in cross-sectional area, the pressure generated by the detonation of the explosive material urges at least a portion of the liner into the recess. The liner, thereby, compresses and / or collapses inward toward a center axis of the void. The pressure of the explosive material may form and / or project a high-velocity jet of liner material away from the void, substantially in the direction of the center axis of the void. In some embodiments, a majority of the jet material originates from the innermost part of the liner.

[0053] In some embodiments, a shaped charge according to the present disclosure includes a void and liner with a geometry that allows the shaped charge to form a jet with substantially no standoff. In some embodiments, the shaped charge has a pressure focus that is located substantially at the terminal end of the liner. By focusing the pressure and / or jet material accelerated by the pressure at the terminal end of the liner, the shaped charge may be smaller, and the shaped charge may be detonated more safely relative to a conventional shaped charge with a standoff.

[0054] A shaped charge according to the present disclosure has a shape to the void of the explosive material and the associated liner that allows for substantially no standoff before the jet is formed. In some embodiments, the liner has a uniform thickness across a surface of the explosive material adjacent the void such that the shape of the exterior surface of the liner (e.g., in the void) is the same as the exterior shape of the explosive material proximate the void. In other embodiments, the liner has a non-uniform thickness, and the shape of the exterior surface of the liner is different from the exterior shape of the explosive material proximate the void.

[0055] In some embodiments, the surface of the explosive material proximate the void of the shaped charge defines a rounded concave base (being axially opposite the open end of the void, where the jet is directed out the open end) in contrast to a conventional conical base. At least a portion of the base may be semi-circular with a constant radius of curvature. In other examples, at least a portion of the base may be parabolic. The concave base, in some embodiments, contacts a convex portion of the sidewall of the void, wherein the sidewalls of the void curve away from the center axis in the direction of the jet. In some embodiments, the sidewalls may form an angle with the center axis between 30° and 60° at the inflection point between the concave portion and the convex portion. The inflection point is where the convex portion of the sidewall and the concave portion of the sidewall meet. In other word, the inflection point is where the sidewall changes from the concave to convex. In some embodiments, the inflection point is an inflection portion that is linear for at least part of the sidewall between the concave portion and the convex portion. In some embodiments, the void has a concave base and a linear sidewall. In some embodiments, the void has a concave base that is continuously concave from the end of the base to the opposing open terminal end of the void.

[0056] By shaping a void of the explosive material, and the liner adjacent to the surface of the explosive material, according to some embodiments of the present disclosure, the shaped charge does not need a standoff. The standoff, in a conventional shaped charge, allows the jet (and slug) to form from the liner past the terminal end of the void and / or the shaped charge. The jet, therefore, has more time to accelerate, but requires more distance from the object targeted by the directed energy. For example, a conventional standoff can be as high as 2 meters. While a standoff can increase the penetration capability of a shaped charge, if the jet has insufficient space to form, the shaped charge can fail to achieve the intended penetration into the target surface. In contrast, a shaped charge according to the present disclosure that does not require a standoff can be used in smaller spaces than a conventional shaped charge and / or use a larger mass of explosive material in the available space. For example, shaped charges can be used in drilling and mining applications to penetrate wellbore casing. The shaped charge is oriented perpendicular to a longitudinal axis of the wellbore to direct the jet of the shaped charge toward the wellbore casing and penetrate the wellbore casing. A shaped charge according to the present disclosure can be used in a smaller wellbore than a conventional shaped charge and / or use a larger mass of explosive material in the limited space in the wellbore.

[0057] In some embodiments, a shaped charge has an explosive material with a void. The void has a center axis between a base of the void and a terminal end of the void. The terminal end is open and directs the jet from the shaped charge in the direction of the center axis. A liner is positioned adjacent the explosive material in the void.

[0058] In some embodiments, the liner includes or is made of glass. For example, the glass may be a silicate glass containing silicon dioxide. In some examples, the glass is substantially all silicon dioxide, while in other examples, the glass contains silicon, oxygen, and other elements, such as a borosilicate glass, soda-lime glass, or crystal lead glass. In some embodiments, the liner includes or is made of metal, such as copper, aluminum, magnesium, tungsten, iron, titanium, vanadium, chromium, lead, tin, cadmium, cobalt, and alloys or combinations thereof. In some embodiments, the liner includes environmentally benign materials, such as glass, aluminum, or iron, that do not contaminate groundwater or surface water. In some embodiments, the liner includes inert materials that are not reactive with water or oxygen in the atmosphere. In some embodiments, the liner includes biodegradable materials that break down over a period of less than 10 years when exposed to outdoor weather and environmental elements. Environmentally benign materials in the liner may allow a shaped charge according to the present disclosure to be used in underground applications (such as drilling or mining) or in aboveground applications, such as avalanche control, in sensitive or protected locations such as United State Forest Service lands.

[0059] The shaped charge has a housing positioned radially around the explosive material relative to the center axis. For example, the housing may be substantially cylindrical, and the explosive material is positioned radially within the housing relative to the center axis. In some embodiments, the housing is integrally formed with the liner, such that the liner and housing are a continuous piece of material. In some embodiments, the housing is separate from the liner. For example, the housing and the liner may be separate pieces that are bonded, adhered, or otherwise affixed to one another. In some embodiments, the shaped charge 100 is a linear shaped charge with a transverse cross-section as described and / or illustrated herein.

[0060] In some embodiments, the housing has a tensile strength that is greater than a tensile strength of the liner. In some examples, the housing includes or is made of a housing material that has a greater tensile strength than a liner material of the liner. In some examples, the housing material and the liner material are the same material, and the housing has a thickness in the radial direction that is greater than a thickness of the liner. The bulk tensile strength of the housing may, therefore, be greater than the bulk tensile strength of the liner even when the housing and liner are the same material. By confining the explosive pressure, the housing can increase the proportion of the energy accelerating the liner. In some embodiments, the housing material is made or and / or includes steel, aluminum, glass, biodegradable materials, environmentally benign materials, plastics, or combinations thereof. In at least one embodiment, the housing material includes stainless steel. In at least one embodiment, the housing material includes polyetheretherketone.

[0061] In some embodiments, the profile of the void and / or the liner adjacent to the void at least partially causes the explosive pressure of the shaped charge to have a focal point substantially at the terminal end. In some embodiments, the profile of the void and / or the liner adjacent to the void at least partially causes the explosive pressure of the shaped charge to have a focal point proximate the terminal end such that the shaped charge has substantially no standoff. For example, the shaped charge may be intended to penetrate a wellbore casing 4 centimeters (cm) thick, and the focal point of the explosive pressure may be approximately 2 cm past the terminal end. The focal point of the explosive pressure may, therefore, be within the target surface (e.g., the wellbore casing) to penetrate the target surface without a standoff.

[0062] In some embodiments, a focal point of shaped charge is positioned along the center axis. In some embodiments, the shaped charge has a plurality of focal points and / or a line of focus along the center axis. For example, the shape of the void and / or liner adjacent to the surface of the void may direct the explosive energy toward an elongated region of the center axis. In some embodiments, the curvature of the surface of the void provides plurality of focal points and / or a line of focus along the center axis. For example, a concave portion of a sidewall of the void (relative to the center axis) may focus the explosive energy to a focal point. In some examples, a linear portion of the sidewall of the void the focuses the explosive energy along focal line of the center axis. In yet other examples, a convex portion of the sidewall of the void focuses the explosive energy along a longer focal line of the center axis 106 than the linear portion. In at least one example, the void is rotationally symmetrical around the center axis. For example, the void may be substantially uniform relative to the center axis as the shaped charge is rotated around the center axis.

[0063] The explosive material can be made of or include one or more high explosives. For example, the explosive material has a relative effectiveness (RE) factor or TNT equivalence of greater than 1.3. In at least one example, the explosive material has an RE factor greater than 1.5. In some embodiments, the explosive material is or includes C-3, C-4, Pentolite, Semtex, Hydrazine mononitrate, Nitroglycerin, Hexogen, Trinitro azetidine, or other high explosives. In a particular example during testing, a shaped charge with a glass liner, a glass housing, and nitroglycerin explosive material according to the geometry described herein penetrated a two-inch thick piece of steel without a standoff.

[0064] In some embodiments, the focal point of the detonation is substantially at the terminal end. In some embodiments, the focal point is past the terminal end by a focal length that is relative to a void length of the void measured from the base to the terminal end. In some embodiments, the focal length is no more than 100% of the void length. For example, in a void length of 6 cm, the focal length may be no more than 6 cm. In some embodiments, the focal length is no more than 50% of the void length. For example, in a void length of 6 cm, the focal length may be no more than 3 cm. In some embodiments, the focal length is no more than 33% of the void length. For example, in a void length of 6 cm, the focal length may be no more than 2 cm.

[0065] As described herein, the focal point may be a linear region and not a single point. In such embodiments, the focal point has an axial length of no more than 2 cm. In some embodiments, the focal point has an axial length of no more than 1 cm. In some embodiments, the focal point has an axial length of no more than 0.5 cm. In some embodiments, the volume which defines the focal point is any region that exhibits at least 80% of the explosive energy relative to the peak explosive energy.

[0066] Some embodiments of a shaped charge according to the present disclosure have a linear portion of the sidewall. In some embodiments, a shaped charge has a plurality of linear portions of the sidewall that direct the explosive energy at different focal points. In some embodiments, the first linear portion has a first angle relative to the center axis and the second linear portion has a second angle relative to the center axis. For example, the first angle may be greater than the second angle. In some examples, the first angle may be less than the second angle.

[0067] The curvature and / or geometry of the void, as well as the materials of the liner, the explosive material, the housing, or combinations thereof affect a shockwave pattern and direction the spall from the liner moves. In some embodiments, the shockwave of the shaped charge directs the spall outward after the focal point / region, in contrast to the slug or jet of liner material of a conventional shaped charge. In at least one embodiment, a radially outward spall disperses the energy and limits damage to objects beyond the focal length of the shaped charge.

[0068] In some embodiments, the void has a substantially flat base with a diameter (or width, in the case of a linear charge). In some embodiments, the base diameter is at least partially related to the void length. For example, the base diameter may be greater than or equal to 10% of the void length. For example, the base diameter may be greater than or equal to 30% of the void length. For example, the base diameter may be greater than or equal to 50% of the void length. In a particular example, the base diameter is approximately 3 cm and the void length is approximately 6 cm.

[0069] In some embodiments, the flat base is flat to within 10% across the base diameter. In some embodiments, the flat base is flat to within 5% across the base diameter. In some embodiments, the flat base is flat to within 1% across the base diameter. During testing, the size of the base diameter affects the size and shape of the spall created after detonation.

[0070] In some embodiments, the contact surface width of the shaped charge proximate the terminal end of the void affects the size and shape of the spall created after detonation. In some embodiments, the contact surface width is no less than 10% of the void length. In some embodiments, the contact surface width is no less than 20% of the void length. In some embodiments, the contact surface width is no less than 30% of the void length. In a particular example, the contact surface width is approximately 1 cm and the void length is approximately 6 cm.

[0071] In some embodiments, the shaped charge directs liner material form the liner toward a target material, and the liner material penetrates the target material before moving radially outward away from the center axis. In some embodiments, the liner material forms a ring of spall (shown after detonation) that expands outward in fragments of the liner material to disperse the energy. During testing, a shaped charge according to the present disclosure directed liner material through a target material containing 2-inch-thick steel with no standoff, and the spall formed a radially outwardly expanding ring moving approximately 45° from the center axis. This dispersed the explosive energy and limited damage to objects on the opposite side of the target material.

[0072] In some embodiments, the spall moves in a direction having a spall angle relative to the center axis that is in a range having an upper value, a lower value, or upper and lower values including any of 15°, 20°, 30°, 45°, 60°, 70°, 75°, or any values therebetween. For example, the spall angle may be between 15° and 75°. In some examples, the spall angle may be between 30° and 60°. In some examples, the spall angle may be greater than 15°. In some examples, the spall angle may be less than 75°. In at least one example, the spall angle may be substantially 45°.

[0073] A shaped charge requiring little or no standoff according to the present disclosure may allow for unique applications in various industries. In some embodiments, a shaped charge is used to puncture a well casing in a downhole drilling or mining environment. In some embodiments, the short or zero standoff of the shaped charge allows a larger mass of explosive material to be positioned in the small space of the wellbore relative to a conventional shaped charge. The shaped charge may be positioned close to the well casing to puncture the well casing and allow fluids to flow between the wellbore and the surrounding formation. In some cases, it is desirable to limit the introduction of liner material, uncombusted explosive material, or combusted waste products of the explosive material into the formation outside the wellbore. The broad dispersion of the spall associated with the short or no standoff, limits the penetration of the liner material and explosive material into the formation. In some embodiments, environmentally benign liner materials, such as glass, can further limit the environmental (e.g., groundwater) effects of the shaped charge and well casing perforating.

[0074] Avalanche control and mass wasting (e.g., landslide, rockslide, mudslide) control is conventionally performed with non-directed explosive devices. Non-directed explosive devices are inefficient and can project debris far from the intended target material. A conventional shaped charge may penetrate the snowpack, rock, or dirt with a jet or slug of material, but a focused application of explosive force may be inefficient at dislodge material from the slope.

[0075] A shaped charge according to the present disclosure directs the explosive energy toward the slope, limiting the projection of debris (both from the shaped charge and from the slope material). In contrast to a conventional shaped charge however, the rapid dispersion of the shockwave through the slope material can apply the directed explosive energy across a larger surface area or volume. The broader application of the explosive energy is similar to a conventional non-directed explosive device while remaining more efficient due the direction of the energy through the shaped charge. The broader application of the explosive energy through a shaped charge according to the present disclosure can thereby limit the projection of debris while providing sufficient energy to the slope material to trigger a controlled avalanche on the slope over a foundation material (such as rock) or other mass wasting event. In some embodiments, environmentally benign liner materials or housing materials, such as glass, can further limit the environmental effects of the shaped charge in sensitive locations where plastic debris or heavy metals can cause lasting damage. Additionally, glass and similar materials dissipate heat very rapidly and mitigate the risk of igniting flammable and explosive materials that might be close to or used right after.

[0076] In some embodiments, a shaped charge according to the present disclosure can be delivered or positioned to the target material by an unmanned aerial vehicle (UAV) such as a multi-rotor device (e.g., a quad-copter drone). In some embodiments, the compact design of the shaped charge allows the shaped charge to be carried by and / or fit inside the chassis of the UAV. In some embodiments, the directed explosive energy of the shaped charge allows a smaller mass of explosive material to be used relative to a conventional non-directed explosive device, making control and flight of the UAV easier. In some embodiments, the directed explosive energy of the shaped charge allows the same mass of explosive material to be used as a non-directed explosive device but with greater effect.

[0077] A conventional shaped charge with a standoff requires precision control, flight, or hovering of the UAV above a target material to efficiently deliver the jet of liner material and explosive energy to the target material. Alternatively, a conventional shaped charge may include a standoff frame that contacts the target material and holds the shaped charge at or near the intended standoff. However, an additional standoff frame adds mass to the device, further limiting the amount of explosive material available in the payload of the UAV. A shaped charge according to the present disclosure operates with little or no standoff, allowing the UAV to land directly on the target material and / or place the shaped charge directly on the target material prior to detonation. In some embodiments, the terminal end of the shaped charge contacts the surface of the target material before a strut or skid of the UAV contacts the target material. In some embodiments, the UAV is configured to release the shaped charge to rest on the target material. For example, the UAV may have an electronically actuated release mechanism to release the shaped charge. In another example, the UAV may have a switch or lever that is actuated upon contacting the target material to release the shaped charge. In some embodiments, the UAV is consumed upon detonation of the shaped charge. Some embodiments of shaped charges described herein can provide a more efficient and more effective explosive energy to a target material via a UAV than either a conventional shaped charge or a conventional non-directed explosive device.

[0078] The housing may include any explosive material described herein. In some embodiments, the housing is integrally formed with a liner. The housing, in some embodiments, include a bottom portion and a top portion that are selectively connectable at a connection mechanism. In some embodiments, the connection mechanism is a twist-lock connection that mates the bottom portion and the top portion without any additional fasteners, such as clips, clamps, threaded bolts, nuts, adhesives, etc. In some embodiments, connection mechanism is a combination of connection mechanisms, such as a twist-lock interface and threaded bolts. In some embodiments, the top portion includes a threaded interface, and the bottom portion includes a complementarily threaded interface to form a first part of the connection mechanism. Upon threading the threaded interfaces together, the connection mechanism may further include set screws, pins, threaded rods, etc. to prevent relative rotation of the threaded interfaces.

[0079] In some embodiments, an explosive material is positioned in the bottom portion and the top portion is subsequently affixed thereto. In some embodiments, the top portion is permanently affixed to the bottom portion, such as by welding or brazing of the top portion to the bottom portion. As the housing is consumable during the explosion of the shaped charge, the bottom portion and top portion may be selectively connectable or permanently connectable by the connection mechanism.

[0080] The housing and liner are, in some embodiments, integrally formed from a single liner and / or housing material. In some embodiments, the bottom portion defines the void. In some embodiments, the top portion includes an opening that provides access to the interior volume of the housing and / or the explosive material therein. In some embodiments, the opening is part of an extended neck that protrudes from the top portion and away from the bottom portion. For example, the extended neck may allow the housing to be further filled with additional explosive material and / or allow positioning of a detonator (e.g., blasting cap) in the top portion. In some embodiments, the opening is recessed in the top portion toward the bottom portion. For example, a recessed opening may simplify filling of the housing with explosive material by providing an integrated funnel into the top portion of the housing.

[0081] In some embodiments, a two-part housing includes a liner with any geometry described herein. In at least some embodiments, shaped charges according to the present disclosure can provide safer handling, positioning, and directing of explosive material compared to conventional devices.

[0082] The present disclosure relates to explosive devices according to at least the examples provided in the sections below:

[0083] [A1] In some embodiments, an explosive device includes an explosive material and a liner. The explosive material includes a void, and the liner is adjacent to a surface of the explosive material in the void. The void has a center axis with a base at a first end of the center axis, a terminal end at a second end of the center axis opposite the first end, and a sidewall therebetween wherein the sidewall has an inflection portion with an angle between 30° and 60° with the center axis.

[0084] [A2] In some embodiments, the void of [A1] is rotationally symmetrical around the center axis.

[0085] [A3] In some embodiments, the void of [A1] or [A2] has a concave portion of the sidewall proximate the base of the void.

[0086] [A4] In some embodiments, the void of any of [A1] through [A3] has a convex portion of the sidewall proximate the base of the void.

[0087] [A5] In some embodiments, the void of any of [A1] through [A4] has a linear portion of the sidewall proximate the base of the void.

[0088] [A6] In some embodiments, the liner of any of [A1] through [A5] includes a silicate glass.

[0089] [A7] In some embodiments, the explosive material of any of [A1] through [A6] includes a liquid explosive.

[0090] [A8] In some embodiments, the explosive material of any of [A1] through [A7] has an RE facto greater than or equal to 1.0.

[0091] [A9] In some embodiments, the sidewall of any of [A1] through [A8] has a first linear portion with a first angle relative to the center axis and a second linear portion with a second angle different from the first angle.

[0092] [A10] In some embodiments, a focal point of the explosive material of any of [A1] through [A 9] is less than 2 centimeters (cm) past the terminal end of the explosive material.

[0093] [A11] In some embodiments, a focal length of the explosive material of any of [A 1] through [A 10] is no more than 100% of a void length of the void of the explosive material.

[0094] [A12] In some embodiments, a spall angle of a liner material of the liner of any of [A 1] through [A 11] after detonation is between 15° and 75° relative to the center axis.

[0095] [B1] In some embodiments, an explosive device includes a housing, an explosive material radially within the housing, and a liner. The explosive material includes a void, and the liner is adjacent to a surface of the explosive material in the void. The void has a center axis with a base at a first end of the center axis, a terminal end at a second end of the center axis opposite the first end, and a sidewall therebetween wherein the sidewall has an inflection portion with an angle between 30° and 60° with the center axis.

[0096] [B2] In some embodiments, the housing of [B1] has greater tensile strength than the liner.

[0097] [B3] In some embodiments, the housing of [B1] or [B2] is integrally formed with the liner.

[0098] [B4] In some embodiments, the explosive material of any of [B1] through [B3] has a focal point at the terminal end of the void.

[0099] [B5] In some embodiments, the explosive material of any of [B1] through [B4] has an RE factor no less than 1.5.

[0100] [B6] In some embodiments, both the housing and the liner of any of [B1] through [B5] include glass.

[0101] [C1] In some embodiments, an explosive device includes a shaped charge and an unmanned aerial vehicle (UAV). The shaped charge includes a housing, an explosive material radially within the housing, and a liner. The explosive material includes a void, and the liner is adjacent to a surface of the explosive material in the void. The void has a center axis with a base at a first end of the center axis, a terminal end at a second end of the center axis opposite the first end, and a sidewall therebetween wherein the sidewall has an inflection portion with an angle between 30° and 60° with the center axis. The UAV is configured to carry the shaped charge with the terminal end at or below a skid of the UAV.

[0102] [C2] In some embodiments, the UAV of [C1] is configured to release the shaped charge before detonation of the shaped charge.

[0103] The articles “a,”“an,” and “the” are intended to mean that there are one or more of the elements in the preceding descriptions. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one implementation” or “an implementation” of the present disclosure are not intended to be interpreted as excluding the existence of additional implementations that also incorporate the recited features. For example, any element described in relation to an implementation herein may be combinable with any element of any other implementation described herein. Numbers, percentages, ratios, or other values stated herein are intended to include that value, and also other values that are “about” or “approximately” the stated value, as would be appreciated by one of ordinary skill in the art encompassed by implementations of the present disclosure. A stated value should therefore be interpreted broadly enough to encompass values that are at least close enough to the stated value to perform a desired function or achieve a desired result. The stated values include at least the variation to be expected in a suitable manufacturing or production process, and may include values that are within 5%, within 1%, within 0.1%, or within 0.01% of a stated value.

[0104] A person having ordinary skill in the art should realize in view of the present disclosure that equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and alterations may be made to implementations disclosed herein without departing from the spirit and scope of the present disclosure. Equivalent constructions, including functional “means-plus-function” clauses are intended to cover the structures described herein as performing the recited function, including both structural equivalents that operate in the same manner, and equivalent structures that provide the same function. It is the express intention of the applicant not to invoke means-plus-function or other functional claiming for any claim except for those in which the words ‘means for’ appear together with an associated function. Each addition, deletion, and modification to the implementations that falls within the meaning and scope of the claims is to be embraced by the claims.

[0105] It should be understood that any directions or reference frames in the preceding description are merely relative directions or movements. For example, any references to “front” and “back” or “top” and “bottom” or “left” and “right” are merely descriptive of the relative position or movement of the related elements.

[0106] The present disclosure may be embodied in other specific forms without departing from its spirit or characteristics. The described implementations are to be considered as illustrative and not restrictive. The scope of the disclosure is, therefore, indicated by the appended claims rather than by the foregoing description. Changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. An explosive device comprising:an explosive material having a void, wherein the void has a center axis with a base at a first end of the center axis, a terminal end at a second end of the center axis opposite the first end, and a sidewall therebetween wherein the sidewall has an inflection portion with an angle between 30° and 60° with the center axis; anda liner adjacent to a surface of the explosive material in the void.

2. The explosive device of claim 1, wherein the void is rotationally symmetrical around the center axis.

3. The explosive device of claim 1 or 2, wherein the void has a concave portion of the sidewall proximate the base of the void.

4. The explosive device of any preceding claim, wherein the void has a convex portion of the sidewall proximate the terminal end of the void.

5. The explosive device of any preceding claim, wherein the void has a linear portion of the sidewall between the base and the terminal end.

6. The explosive device of any preceding claim, wherein the liner includes silicate glass.

7. The explosive device of any preceding claim, wherein the explosive material includes a liquid explosive.

8. The explosive device of any preceding claim, wherein the explosive material has a relative effectiveness (RE) factor greater than or equal to 1.0.

9. The explosive device of any preceding claim, wherein the sidewall has a first linear portion with a first angle relative to the center axis and a second linear portion with a second angle different from the first angle.

10. The explosive device of any preceding claim, wherein a focal point of the explosive material is less than 2 centimeters (cm) past the terminal end of the explosive material.

11. The explosive device of any preceding claim, wherein a focal length of the explosive material is no more than 100% of a void length of the void of the explosive material.

12. The explosive device of any preceding claim, wherein a spall angle of a liner material of the liner after detonation is between 15° and 75° relative to the center axis.

13. An explosive device comprising:a housing;an explosive material positioned radially within the housing and the explosive material having a void, wherein the void has a center axis with a base at a first end of the center axis, a terminal end at a second end of the center axis opposite the first end, and a sidewall therebetween wherein the sidewall has an inflection portion with an angle between 30° and 60° with the center axis; anda liner adjacent to a surface of the explosive material in the void.

14. The explosive device of claim 13, wherein the housing has greater tensile strength than the liner.

15. The explosive device of claim 13 or 14, wherein the housing is integrally formed with the liner.

16. The explosive device of any of claims 13 through 15, wherein the explosive material has a focal point at the terminal end of the void.

17. The explosive device of any of claims 13 through 16, wherein the explosive material has an RE factor no less than 1.5.

18. The explosive device of any of claims 13 through 17, wherein both the housing and the liner include glass.

19. An explosive device comprising:a shaped charge, the shaped charge including:a housing,an explosive material positioned radially within the housing and the explosive material having a void, wherein the void has a center axis with a base at a first end of the center axis, a terminal end at a second end of the center axis opposite the first end, and a sidewall therebetween wherein the sidewall has an inflection portion with an angle between 30° and 60° with the center axis, anda liner adjacent to a surface of the explosive material in the void; andan unmanned aerial vehicle (UAV) configured to carry the shaped charge with the terminal end at or below a skid of the UAV.

20. The explosive device of claim 19, wherein the UAV is configured to release the shaped charge before detonation of the shaped charge.

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