Patent Publication Number: US-9897421-B2

Title: Enhanced linear shaped charge including spinal charge element

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of Ser. No. 14/951,680, filed on Nov. 25, 2015, which is a division of U.S. patent application Ser. No. 13/964,300, filed Aug. 12, 2013, both disclosures which are incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Various embodiments of the disclosure pertain to linear shaped charges, and more particularly, to a linear shaped charge including a spinal charge element. 
     A linear shaped charge (LSC) is an explosive device consisting of an explosive material encased in a metal tube (or sheath). The sheath typically has a V-shaped cross-sectional profile that defines a lower apex. When the LSC is detonated at one end, a planar detonation wave propagates axially along the length of the LSC. As each cross-section is detonated, a high-velocity molten jet of sheath material is projected downward from the lower apex. The molten jet is capable of cutting through various metallic and non-metallic targets of various thicknesses depending on the explosive material load and the sheath material. 
     A conventional LSC generates a planar detonation wave that travels parallel to the length of the sheath and therefore perpendicular to the projected molten jet. Since the detonation wave is perpendicular to the molten jet, the molten jet does not realize the full force of the detonation wave and the detonation efficiency of the LSC is diminished. 
     BRIEF DESCRIPTION 
     According to an embodiment, an enhanced linear shaped charge (X-Jet) includes a sheath and a spinal charge element. The sheath extends along an axis between a first end and a second end to define a sheath length. The sheath has a first hollowed chevron-shaped cross-section that defines a main charge cavity, an upper apex, and a lower apex. The spinal charge element is disposed within the main charge cavity and abuts the upper apex. The spinal charge element further includes a spinal casing that extends along the sheath length to define a spinal length. The spinal casing has a hollowed cross-section defining a spinal charge cavity. 
     According to another embodiment, a method of detonating a linear shaped charge (LSC) having a sheath configured to contain explosive charge material comprises loading a spinal charge material in an upper apex of the sheath to generate a spinal detonation wave having a spinal detonation velocity. The method further comprises loading a main charge material in the sheath to completely surround the spinal charge material. The main charge material is configured to produce a main detonation wave having a main detonation velocity that is less than the spinal detonation velocity. The method further comprises detonating the spinal charge material to generate the spinal detonation wave that travels in a spinal direction. The method further comprises detonating the main charge material via the spinal detonation wave to generate the main detonation wave. The main detonation wave generates a molten jet that projects from the X-jet and travels in a direction that is parallel to the direction of the main detonation wave. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  is an isometric view of an X-Jet device according to an embodiment of the disclosure; 
         FIG. 2  is a cross-sectional view of an X-Jet device containing explosive charge material according to an embodiment; 
         FIG. 3  is a cross-sectional view of an X-Jet device contain explosive charge material according to another embodiment; 
         FIG. 4  illustrates the directions of the detonation waves and the projected jet following detonation of the explosive charge material of the X-Jet according to an embodiment; and 
         FIG. 5  is a flow diagram illustrating a method of assembling and detonating an X-Jet according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     Referring to  FIGS. 1 and 2 , a linear shaped charge (LSC)  100  is illustrated according to an embodiment. The LSC  100  is formed as an enhanced LSC, hereinafter referred to as an “X-Jet”  100 , which improves efficiency and increases target penetration capability of a molten jet projected therefrom. 
     The X-Jet  100  includes a sheath  102  and a spinal charge element  104 . The sheath  102  has a plurality of cross-sectional regions  106  extending along an axis (e.g., an X-axis) between a first end and a second end to define a sheath  102  length (L S ). The sheath  102  has a first hollowed chevron-shaped cross-section that defines the main charge cavity  108 . The chevron-shaped cross-section defines an upper apex  110 , a lower apex  112 , a first leg  114 , and a second leg  116 . The first leg  114  and the second leg  116  are separated from one another by a void region  118 . The sheath  102  may be formed from various materials including, but not limited to, aluminum, copper, tungsten, tantalum, depleted uranium, lead, tin, cadmium, cobalt, magnesium, titanium, zinc, zirconium, molybdenum, beryllium, nickel, silver, gold, and platinum. The spinal charge element  104  is located within the main charge cavity  108 . The spinal charge element  104  may include a spinal casing  120  having a hollowed cross-section that defines a spinal charge cavity  122 . The cross-section of the spinal charge element  104  may have various shapes including, but not limited to, a circular-shaped cross-section, a square-shaped cross-section, a diamond-shaped cross-section, and a polygonal-shape cross-section. In at least one embodiment, the spinal casing  120  extends along length (e.g., X-axis) of the sheath  102  to define a spinal length, and is aligned with the upper apex  110  and lower apex  112 . The size of the spinal charge element  104  is less than the size of the upper apex  110  such that no air gap exists between the sheath  102  and the spinal casing  120 . 
     In at least one embodiment, the spinal charge element  104  is formed as a separated spinal charge element  104  that is separate from the sheath  102  (see  FIGS. 1-2 ). The spinal casing  120  may be formed from various materials including, but not limited to, metal and polymer. The spinal casing  120  and the sheath  102  may be formed of the same material, or of different materials. 
     In another embodiment illustrated in  FIG. 3 , the spinal charge element  104  is formed as an integrated spinal charge element  124  such that the spinal casing  120  is integrally formed with sheath  102 . The integrated spinal charge element  124  may be formed, for example, by forming a spinal charge cavity through the outer and inner walls of the upper apex  110  (i.e., hollowing the upper apex  110 ) to define the spinal charge cavity  122 . Accordingly, the integrated spinal charge element  124  is integrally formed from the upper apex  110  such that the sheath  102  and the integrated spinal charge element  124  are formed from the same material. 
     The X-Jet  100  may further include an explosive charge material contained in the main charge cavity  108  and/or the spinal charge cavity  122 . When each of the main and spinal charge cavities  108 ,  122  is filled with a respective explosive charge material, the X-Jet is configured to generate a detonation wave  130  (see  FIG. 4 ), which in turn projects a molten jet  132  that travels in a direction parallel to the detonation wave  130 . 
     Referring still to  FIGS. 1-4 , for example, the main charge cavity  108  may be filled with a first type of explosive charge material  126  (i.e., a main charge material  126 ), and the spinal charge cavity  122  may be filled with a second type of explosive charge material  128  (i.e., the spinal charge material  128 ) that is different from the main charge material  126 . Upon detonation, each of the spinal charge material and the main charge material produce a detonation wave having a detonation velocity. The detonation velocity of the explosive charge material dictates the rate at which the respective detonation wave propagates (i.e., the propagation rate). 
     In at least one embodiment, the main charge material  126  may have a detonation velocity (i.e., a main detonation velocity) that is less than the detonation velocity (i.e., spinal detonation velocity) of the spinal charge material  128 . For example, the main charge cavity  108  may be filled with Hexanitrostilbene (HNS), which may have a detonation velocity ranging from 6000 meters/second to 7000 meters/second. The spinal charge cavity  122  may be filled with octogen (HMX), which may have a detonation velocity ranging from 8000 meters/second to 10,000 meters/second. Accordingly, when the main and spinal charge materials  126 ,  128  are detonated, the detonation of the spinal charge material  128  shall propagate along L S  at a rate faster than the detonation of the main charge material  126 . 
     The difference in detonation propagation rate may also be achieved by packing the main and spinal explosive charge materials  126 ,  128  at different densities with respect to one another. For example, the spinal charge material  128  may be packed in the spinal charge cavity  122  at a packing density greater than a packing density at which the main charge material  126  is packed in the main charge cavity  108 . That is, the spinal charge material  128  is compressed within the spinal charge cavity  122  at a force greater than the main charge material  126  compressed within the main charge cavity  108 . In at least one embodiment, the packing density of the spinal charge material  128  may be greater than the packing density of the main charge material  126  by a ratio ranging from approximately 1.2:1.0 to approximately 2.0:1.0. It is appreciated, however, that the packing density ratio is not limited thereto. 
     Turning now to  FIG. 4 , the directions of the detonation waves in an X-Jet  100  are illustrated following detonation of the spinal charge material  128 . The detonation may occur at various locations of the X-Jet  100 . In at least one embodiment, a first detonation is initiated at one end of the sheath  102 . It is appreciated, however, that the detonation may occur at the middle of the sheath, for example, at the middle of the spinal charge element  104 . The detonation of the spinal charge material  128  generates a spinal detonation wave  131  that travels parallel to L S . The spinal detonation wave  131  then continues to propagate along the length of the X-Jet toward the opposing end(s) of the sheath  102 . 
     In response to the spinal detonation wave  131 , a subsequent detonation of the main charge material  126  is induced, generating a main detonation wave  130  in the main charge material  126 . The main detonation wave  130  travels perpendicular to the length of the X-Jet and toward the lower apex  112 . As the spinal detonation wave  131  propagates along L S  at spinal a propagation rate (i.e., a spinal propagation rate) that is faster than the propagation rate (i.e., main propagation rate) of the main detonation wave  130 , the main charge material  126  is detonated at each respective cross-sectional region  106 . The detonation of the main charge material  126  at each respective cross-section  106  creates a main detonation wave  130  that propagates toward the lower apex  112  at each respective cross section. Accordingly, the main charge material  126  is sequentially detonated in an asynchronous manner (See  FIG. 4 ), as opposed to detonating the entire cross-section of the sheath  102  simultaneously. 
     The main detonation wave  130  in the main charge material  126  causes the legs  114  and  116  to collapse and generates a molten jet  132 . The molten jet  132  travels in a direction that is parallel to the direction of the main detonation wave  130  and is propelled from the sheath  102  in response to the detonation wave  130 . In at least one embodiment, the molten jet  132  is propelled from the sheath  102  at the lower apex  112 . Unlike a conventional LSC, which projects a molten jet in a direction perpendicular to a main detonation wave  130  propagating parallel to L S , the X-Jet  100  directs the main detonation wave  130  in a direction parallel to the molten jet  132 . The molten jet  132 , therefore, realizes the maximum energy and potential of the detonation wave  130 . Accordingly, the X-Jet  100  achieves improved detonation efficiency and increases the penetration capability of a molten jet  132 . 
     Turning now to  FIG. 5 , a flow diagram illustrates a method of assembling and detonating an X-Jet according to at least one embodiment. The method begins at operation  500 , and proceeds to operation  502  where a spinal charge material is loaded at an upper apex of the X-Jet sheath. In at least one example, a spinal charge containing the spinal charge material extends along the upper apex. At operation  504 , a main charge material is loaded in the sheath. The main charge material may completely surround the spinal charge material. According to one example, the main charge material may be different from the spinal charge material and have a different detonation velocity than the detonation velocity of the spinal charge material. In another example, the main charge material may be the same as the spinal charge material but loaded according to a packing density that is different from the packing density of the spinal charge material. 
     At operation  506 , the spinal charge material is detonated to generate a first propagation rate (i.e., a spinal propagation rate). The detonation of the spinal charge material induces a spinal detonation wave that propagates along the length of the X-Jet. At operation  508 , the spinal detonation wave induces a detonation of the main charge material. The main charge detonation has a main charge propagation rate (i.e., a main charge detonation rate) that is less than the propagation rate of the spinal detonation wave and propagates in a direction perpendicular to the propagation direction of the spinal detonation wave. At operation  510 , a molten jet traveling in a direction parallel to the main detonation wave is generated in response to the detonation of the main charge material, and the method ends at operation  512 . Accordingly, detonation efficiency is improved and overall penetration capability of the molten jet is increased. 
     While various embodiments have been described, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the various embodiments or inventive teachings without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims.