Abstract:
Applique armor has a mounting plate with a channel that receives flanged beam mounted on a structure to be protected. A box is attached to the mounting plate opposite the channel. The box contains an open cell layer. When applied to a structure, adjacent mounting plates interlock using mortise and tenon, and mounting plates arranged one behind another overlap with boxes on neighboring mounting plates to eliminate gaps in the armor.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is derived from and claims priority to U.S. Provisional Application No. 62/024,142, filed Jul. 14, 2014 and hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to applique armor for military vehicles, and a system for rapidly mounting and removing applique armor from any vehicle. 
       BACKGROUND 
       [0003]    Improvised explosive devices (IEDs) have proved to be a deadly threat to unarmoured military vehicles such as trucks and high mobility multipurpose vehicles (Humvees) which lack sufficient armor protection. IEDs have further evolved in lethality to menace wheeled armored vehicles such as the “Stryker”, as well as tracked vehicles such as main battle tanks. 
         [0004]    The effectiveness of IEDs is especially apparent in asymmetrical warfare scenarios such as found in Middle East conflicts, where there is no clear frontline and no completely secure rear areas where vehicles can operate with impunity. Casualty lists numbering in the thousands are sad testament to the effects of IEDs on unarmored and insufficiently armored vehicles as used in the field today. 
         [0005]    While steps have been taken to “up-armor” vehicles, for example, by permanently attaching rolled homogeneous armor plate (RHA) to the sides and undersides of vehicles, there are drawbacks to such measures. The armor plate adds significant weight to the vehicle and requires extensive and time consuming structural modifications to permanently mount the armor on the chassis, hull, or other parts of the vehicle. There is clearly a need for effective applique armor that can be easily mounted to vehicles (and removed therefrom when not required) to improve their resistance to blast damage from IEDs and other ballistic threats and thereby afford greater safety and survivability to their crews in combat. 
       SUMMARY 
       [0006]    Applique armor according to the invention, when compared with rolled homogeneous armor steel plate, is expected to provide advantages of lighter specific weight, increased energy absorption, easier mounting and transport and reduction in life cycle cost with virtually no maintenance cost and ease of storage and transport. In addition, when vehicles do not require the additional applique armor it can be transferred easily to any other type of vehicle for immediate use (provided that the mounting system, such as I-beams, are pre-welded to the vehicle), thus conserving significant amounts of funding. A maintenance free life cycle of more than 20 years is expected. 
         [0007]    An example of applique armor according to the invention comprises a mounting plate having first and second surfaces oppositely disposed. A channel is positioned in the mounting plate and extends along the first surface. A box is attached to the second surface of the mounting plate. An open cell layer may be positioned within the box. In a particular example embodiment the channel has a T shaped cross section. 
         [0008]    By way of further example the mounting plate comprises first and second edges oppositely disposed and extending substantially parallel to the channel. In this example a mortise is positioned in the mounting plate and extends along the first edge. A tenon extends along the second edge and projects outwardly therefrom. In an example embodiment he mortise and the tenon have a T shaped cross section. In another example the mortise and the tenon have a bulbous head cross section. 
         [0009]    In an example embodiment the mounting plate has a first end and a second end oppositely disposed. In this example the box has a first end and a second end oppositely disposed, and the first end of the box is offset from the first end of the mounting plate. By way of further example the second end of the box is also offset from the second end of the mounting plate. 
         [0010]    In another example embodiment the first end of the box projects outwardly from the first end of the mounting plate, and the second end of the mounting plate projects outwardly from the second end of the box. In a particular example embodiment the mounting plate, the box and the open cell layer are made of titanium. 
         [0011]    In a specific example embodiment the box comprises first and second end panels oppositely disposed, and first and second side panels oppositely disposed. In this example the first and second end panels have a thickness less than a thickness of the first and second side panels. By way of example the applique armor may further comprises an open cell layer positioned within the box, wherein the open cell layer is oriented with open ends of cells facing the first and second end panels. 
         [0012]    In another example embodiment the box comprises a panel positioned in spaced relation to the second surface of the mounting plate. The panel forms a bottom of the box and has a plurality of vent holes therethrough. 
         [0013]    The invention also encompasses, in combination, applique armor and a mounting system for mounting the applique armor to a structure. In an example embodiment the combination comprises at least one mounting plate having first and second surfaces oppositely disposed. A channel is positioned in the at least one mounting plate and extends along the first surface. A box is attached to the second surface of the at least one mounting plate. A beam is received within the channel, the beam being attachable to the structure. 
         [0014]    Another example may further comprise an open cell layer positioned within the box. In an example embodiment the channel has a T shaped cross section and the beam comprises a web and a flange attached to the web. The web and flange are sized to be received within the channel. 
         [0015]    In another example embodiment of the combination, the at least one mounting plate further comprises first and second edges oppositely disposed and extending substantially parallel to the channel. In this example a mortise is positioned in the mounting plate and extends along the first edge. Further in this example a tenon extends along the second edge and projects outwardly therefrom. In a specific example embodiment the mortise and the tenon have a T shaped cross section. In another example embodiment, the mortise and the tenon have a bulbous head cross section. 
         [0016]    In another example embodiment the at least one mounting plate has a first end and a second end oppositely disposed and the box has a first end and a second end oppositely disposed. In this example the first end of the box is offset from the first end of the mounting plate. In a further example embodiment the second end of the box is offset from the second end of the mounting plate. By way of further example, the first end of the box projects outwardly from the first end of the mounting plate, and the second end of the mounting plate projects outwardly from the second end of the box. 
         [0017]    By way of example a slot is positioned proximate to one end of the beam and a wedge is removably positioned within the slot for retaining the at least one mounting plate on the beam. 
         [0018]    An example combination of applique armor and a mounting system for mounting the applique armor to a structure further comprises a plurality of mounting plates. In this example each of the mounting plate comprises first and second surfaces oppositely disposed. A channel extends along the first surface. A box is attached to the second surface of each of the mounting plates. By way of example the combination further comprises a plurality of beams received within the channels. The beams are attachable to the structure, and the mounting plates are arranged on the beams one behind another and one adjacent another. 
         [0019]    By way of further example an open cell layer is positioned within each the box. In an example embodiment each of the channels has a T shaped cross section and each of the beams comprises a web and a flange attached to the web, the webs and flanges being sized to be received within the channels. 
         [0020]    In a further example embodiment, each of the mounting plates comprises first and second edges oppositely disposed and extending substantially parallel to the channel. A mortise is positioned in the mounting plate and extends along the first edge. A tenon extends along the second edge and projects outwardly therefrom. In this example, for the mounting plates positioned adjacent to one another, the tenon on one of the mounting plates engages a mortise on another of the mounting plates. 
         [0021]    In another example each of the mounting plates has a first end and a second end oppositely disposed. Each of the boxes has a first end and a second end oppositely disposed. In this example the first ends of each of the boxes project outwardly from the first ends of each of the mounting plates, and the second ends of each of the mounting plates project outwardly from each of the second ends of each of the boxes. Additionally by way of example, for the mounting plates positioned one behind another, the second ends of the mounting plates overlap the first ends of the boxes. 
         [0022]    Also by way of example, first and second slots are positioned proximate to opposite ends of each of the beams, and first and second wedges are removably positioned within the slots for retaining the mounting plates on the beam. 
         [0023]    The invention further comprises a method of mounting applique armor on a structure. In one example embodiment the method comprises:
       mounting at least one beam on the structure;   engaging a channel in a first mounting plate with the at least one beam;   sliding the first mounting plate lengthwise along the beam to a first position.       
 
         [0027]    By way of example, the method further includes:
       engaging a channel in a second mounting plate with the at least one beam;   sliding the second mounting plate along the at least one beam to a second position adjacent to the first mounting plate.       
 
         [0030]    An example method also includes overlapping a portion of the first mounting plate with a portion of the second mounting plate upon sliding the second mounting plate into the second position. 
         [0031]    An example method further comprises:
       mounting at least a second beam on the structure in spaced relation adjacent to the at least one beam;   engaging a channel in a second mounting plate the second beam;   sliding the second mounting plate along the second beam to a second position adjacent to the one mounting plate.       
 
         [0035]    This example method may further comprise engaging a mortise on the second mounting plate with a tenon on the first mounting plate upon sliding the second mounting plate into the second position, or engaging a tenon on the second mounting plate with a mortise on the first mounting plate upon sliding the second mounting plate into the second position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]      FIG. 1  is a partially exploded isometric view of an example embodiment of applique armor according to the invention; 
           [0037]      FIG. 2  is an isometric view of another example embodiment of applique armor according to the invention; 
           [0038]      FIG. 3  is an isometric view of another example embodiment of applique armor according to the invention; 
           [0039]      FIG. 4  is an isometric view of an example combination applique armor and mounting according to the invention; 
           [0040]      FIGS. 5-7  are isometric views of example mounting components used with the applique armor according to the invention; 
           [0041]      FIG. 8  is an isometric view illustrating an example method of mounting applique armor according to the invention; and 
           [0042]      FIGS. 9-11  illustrate potential example uses of applique armor according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0043]      FIG. 1  shows an example embodiment of an applique armor unit  10  according to the invention. Armor unit  10  comprises a mounting plate  12  having a first surface  14  and a second surface  16  oppositely disposed. A channel  18  is positioned in mounting plate  12  and extends along the first surface  14 . In this example the channel has a “T” shaped cross section, although other cross sectional shapes are of course feasible. Mounting plate  12  further comprises a first edge  20  and a second edge  22  oppositely disposed. Edges  20  and  22  extend substantially parallel to the channel  18 . A mortise  24  is positioned within the mounting plate  12  and extends along the first edge  20 , and a tenon  26  extends along the second edge  22  and projects outwardly therefrom. In the example embodiment shown in  FIG. 1  the mortise and tenon have “T” shaped cross sections. Other cross sectional shapes, such as the bulbous head cross section shown in  FIG. 2 , are also feasible. Mounting plate  12  also has a first end  28  and a second end  30  oppositely disposed. 
         [0044]    A box  32  is attached to the second surface  16  of mounting plate  12 . In this example box  32  comprises a top panel  34 , a bottom panel  36  (see  FIG. 3 ) positioned in spaced relation to the top panel  34  and to the second surface  16  of the mounting plate  12 . Top panel  34  and bottom panel  36  are attached to oppositely disposed first and second side panels  38  and  40  and oppositely disposed first and second end panels  42  and  44 . It is advantageous to make the end panels  42  and  44  thinner than the side panels  38  and  40  as explained below. As shown in  FIG. 3 , the bottom panel  36  may have a plurality of vent holes  46 . An open cell layer  48  is positioned within box  32 . The open cell layer may take a hexagonal honeycomb form as shown in  FIG. 1 , or may be an “egg crate” construction as shown in  FIG. 2 . Open cell layer  48  may be oriented with the open ends  50  of the cells  52  facing top and bottom panels  34  and  36  as shown in  FIG. 1 , or facing first and second ends  42  and  44  as shown in  FIG. 2 . 
         [0045]    Box  32  has first and second ends  54  and  56  which are offset from the first and second ends  28  and  30  of the mounting plate  12 . In the examples shown in  FIGS. 1-3  the offset is manifest by the first end  54  of box  32  projecting outwardly from the first end  28  of mounting plate  12 , and the second end  30  of the mounting plate  12  projecting from the second end  56  of the box  32 . This offset configuration permits overlapping engagement between applique armor units when arranged one behind another as described below. 
         [0046]      FIG. 4  shows a combination applique armor units  10  and mounting system  58 . Combination  58  comprises one or more applique armor units  10  (mounting plate  12  and box  32 ) and one or more beams  60 . In this example beams  60  are “I” beams each having a web  62  and flanges  64  attached to the web (see  FIG. 5 ). One or more beams  60  are attached to the structure to be protected by the applique armor, for example, the chassis of a vehicle, and the applique armor units  10  are mounted on the beams, the flange and at least a portion of the web being received within the channels  18  of the mounting plates  12 . Use of the flanged I beam  60  with a channel  18  having a compatible cross sectional shape permits easy mounting and dismounting of the applique armor units  10  while also reliably retaining the applique armor units to the protected structure (not shown). When used in combination, the applique armor units  10  cooperate in interlocking fashion such that for mounting plates  12  on applique units  10   a  positioned adjacent to one another, the tenon  26  on one mounting plate engages the mortise  24  on the adjacent mounting plate. Furthermore, for mounting plates  12  on applique units  10   b  positioned one behind another, the second end  30  of one mounting plate  12  overlaps the first end  42  of box  32  of the applique armor unit behind. This interlocking engagement adds structural integrity and eliminates gaps between the applique armor units  10 , and is expected to provide improved armor protection against blast shock, heat, gas and shrapnel. As shown in  FIG. 2 , additional protection against blast is expected to be afforded by orienting open cell layer  48  with the open ends  50  of the cells  52  facing the first and second end panels  42  and  44  and having the end panels thinner than the side panels  38  and  40 . Being thinner, these end panels are expected to blow out when the box  32  is subject to blast, and thereby direct a majority of the blast toward the ends of the applique armor units  10 . By arranging the beams  60  lengthwise along a vehicle for example, the blast effects are expected to be directed toward the front and the rear, and not in a normal upward thrust thus preventing harm to the occupants in the personnel compartment above. Gaseous blast and heat energy and fragments are thus directed substantially horizontally away from the vehicle towards its front and rear, and the mounting plates  12  along with bottom and top panels  36  and  34  prevent fragments from entering the vehicle. 
         [0047]    As shown in  FIGS. 5 and 6 , the beams  60  have slots  66  positioned in the flanges  64  proximate the ends of the beam. Wedge retaining plates  68 , shown in  FIG. 7 , are positioned within the slots  66  to retain the applique armor units  10  to the beams  60 . The wedges are readily removable to facilitate removal and replacement of units  10 . Each wedge  68  may be attached to a beam  60  via a chain  70  for retaining the wedges when they are not engaged within the slots. 
         [0048]    Applique armor units  10  may be easily and quickly mounted on a structure, such as a vehicle. One or more beams  60  are attached to the bottom of the chassis, for example by welding, and, as shown in  FIG. 8 , the applique armor units  10  are slid onto the beam by engaging the flange  64  and web  62  with the channel  18  in the mounting plates  12 . To reduce sliding friction between the I beams and the mounting plates it is advantageous to position a lubricant, such as a layer of polytetrafluoroethylene (Teflon), grease, or silicone on the surface of the lower flange  64  that interfaces with the channel  18 . Other lubricants are also feasible. The number of beams  60  and number of applique armor units  10  can be tailored to the size of the vehicle to provide thorough protection. As the applique armor units  10  are slid onto the beams  60 , the tenons  26  engage mortises  24  on adjacent units and the mounting plates  12  and boxes  32  overlap for units positioned one behind another as shown in  FIG. 4 . The applique armor units  10  may be supported on a wheeled hydraulic jack or scissor jack when engaging the beams. Use of a wheeled support jack permits faster manual mounting and dismounting of armor units  10 . Furthermore, no tools are needed to assemble the applique armor according to the invention, and thus up-armoring a vehicle can be accomplished under rough conditions as encountered in the field. 
         [0049]    In a practical example, applique armor units  10  can be built to standard dimensions, with 2 feet by 4 feet by about 4-6 inches in depth being thought advantageous, although 2 feet by 3 feet, 2 feet by 2 feet, and 2 feet by 1 foot are also feasible, thereby permitting a combination of unit sizes to amply protect any unprotected areas of the vehicle. Candidate materials for the mounting plate  12 , the box  32  and the open cell layer include metals, in particular titanium in view of its high strength and relatively low density. 
         [0050]    It is expected that advantageous protection for a minimum weight penalty can be achieved if titanium alloy meeting military specification Ti MIL-BTL 46077G or similar protective material is used for the applique armor units  10 . In a practical example of an all titanium design, the mounting plate  12  is 2.1 inches thick, the top panel  34  is 0.406 inches thick, the bottom panel  36  is 0.25 inches thick, the open cells  48  are 2.0 inches deep and 0.125 inches thick, side panels  38  and  40  are 0.25 inches thick and blow-out end panels  42  and  44  are 0.0156 inches thick. Further in the way of a practical design, the channel  18  is dimensioned to receive a wide flange I beam  60 , in a particular example, an ASTM standard W4X13 I beam wherein the flanges  64  have a width of about 4 inches. 
         [0051]      FIGS. 9-11  illustrate a few potential uses of the applique armor according to the invention.  FIG. 9  shows a thin skinned military vehicle  72  “up-armored” through the use of applique armor  10  used on the sides and bottom of the vehicle where mine damage and small arms fire can be expected. Similarly, as shown in  FIG. 10 , areas on aircraft  74  vulnerable to ground fire, such as the underbelly, may be covered with applique armor  10  for increased protection. As shown in  FIG. 11 , naval vessels  76 , especially those designed for riverine and littoral combat, where small arms fire is encountered, can benefit from the increased protection afforded to hull and superstructure by applique armor  10 . 
         [0052]    The applique armor according to the invention is expected to secure numerous advantages over rolled homogeneous armor plate made of steel. For example, attachment of the applique armor units  10  to a vehicle is greatly simplified as compared with armor plate and can be done under primitive conditions in the field. Mounting and dismounting of the applique armor on the I beams takes little time, allowing for rapid replacement of damaged boxes. Furthermore, undamaged boxes can readily be salvaged from otherwise damaged vehicles and used on other vehicles. Due to their regular and uniform shape, the units  10  can be stacked and transported conveniently. The relatively modest depth of the units (4-6 inches) ensures that they will not significantly affect the ground clearance of most vehicles. When used on the underside of a vehicle, the applique armor lowers its center of gravity, thus increasing vehicle stability. 
         [0053]    The applique armor according to the invention is also expected to provide the same or better protection than armor plate at a lower weight penalty. Theoretical calculations comparing applique armor according to the invention with 2 inch rolled homogeneous armor plate currently used on Stryker armored personnel carriers indicate that, while both are capable of absorbing a blast producing an overpressure of about 61,460 psi, the applique armor according to the invention and having the thickness dimensions as described above weighs approximately 28% less than the rolled homogeneous armor plate of steel, thereby producing a significant weight savings. The calculations include the weight of the I beam mounting structure.