Abstract:
A wearable wound simulant including a skin replica having the appearance of a particular region of the human body, examples including but not limited to a leg, arm, torso, or stomach, and a wound disposed along the skin replica is described. The skin replica includes a plurality of bendable layers arranged to replicate the visual and tactile properties of human tissues and at least one tear resistant layer comprised of a fabric material disposed between two bendable layers. The tear resistant layers are less stretchable than the bendable layers so as to prevent the bendable layers from stretching beyond their failure threshold. Design elements of the present invention facilitate the visual, tactile, and functional aspects of a battlefield wound so as to allow for the diagnosis of injuries associated therewith. Furthermore, the present invention allows for the insertion of a needle or the like, the probing and/or packing of wounds, the compression of vascular simulants to stop or limit blood loss, and the replacement of dislodged organs.

Description:
FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     This invention was made with Government support under Contract No. N61339-07-C-0038 awarded by the U.S. Army Research, Development, and Engineering Command, Simulation and Training Technology Center. The Government may have certain rights in one or more forms of the invention. 
    
    
     CROSS REFERENCE TO RELATED APPLICATIONS 
     None. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a device capable of simulating a battlefield wound for training purposes. Specifically, the invention includes a plurality of bendable layers disposed about a fabric layer to form a self-sealing structure. Fabric layer constrains the bendable layers so as to avoid stretch conditions which exceed the failure threshold of the bendable layers. The device includes a three-dimensional structure which replicates the appearance and functionality of an impact, penetration, or blast induced injury. 
     2. Background 
     The survivability of a wounded soldier has never been better due in large part to improvements in the field of medical treatment, including treatment by non-medical personnel. The medical treatment skills of soldiers are developed by intensely realistic training sessions during which actors wear makeup and/or vinyl devices which replicate the appearance of horrific, life-threatening wounds. 
     Makeup includes the application of compositions onto the skin of an actor. This approach to simulating a wound has several deficiencies. For example, the application process can be quite lengthy depending on the severity of a wound and the degree of detail desired. Also, the appearance achieved with makeup degrades over time and with use. Furthermore, the visual rather than functional aspect of makeup limits training to a recitation of treatment steps by a trainee. Accordingly, makeup lacks the realism required to properly train non-medical personnel and is not conducive to training sessions involving many different wound types and/or multiple trainees. 
     Vinyl devices are molded elements which partially conform to a particular body region and superficially represent a wound. Typically, paint is applied to the surface of such devices to enhance and supplement their overall appearance. Accordingly, presently known devices suffer from a wide variety of deficiencies related to appearance, functional realism, and teaching value. 
     From an appearance perspective, presently known devices do not accurately replicate the visual properties of tissues and bone. Such devices are attached to an actor via straps which are secured to the device via rivets, which eventually tear free from the device. Also, the appearance of such devices degrades over time as paint flakes off the device and nicks, cuts, and tears compromise the shape and integrity thereof. Furthermore, such devices lack the elasticity to properly conform to the human body. Finally, such devices do not completely surround a body region, but rather contact a small portion thereof. 
     From a functional perspective, presently known devices do not accurately replicate the tactile properties, namely, softness, hardness, compressibility, pliability, resiliency, flexibility, bendability and/or elasticity, of tissues and bone. Also, the construction of such devices precludes functional realism, including the replication of seeping-type wounds and the probing and/or packing of wounds. Furthermore, vascular elements are simulated with rigid tubes which do not replicate the compressibility of vascular structures. 
     In terms of teaching value, presently known devices simulate the wound only and therefore do not provide a clinically accurate representation of a vascular system adjacent thereto, which is sometimes required for the holistic treatment of an injury. Also, the two-dimensional nature of such devices does not enable a student to probe and pack a wound. Furthermore, such devices preclude the use of needles and the like because resultant holes compromise the integrity of the device. Finally, such devices lack moving parts to replicate internal organs dislodged from a wound. 
     As is readily apparent from the discussions above, the related arts do not include a wearable wound simulant which replicates the visual, tactile, and functional aspects of battlefield wounds and the tissues and structures adjacent thereto. 
     Accordingly, what is required is a wearable wound simulant capable of replicating such properties so as to facilitate a realistic medical training tool. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a wearable wound simulant capable of replicating the visual, tactile, and functional aspects of a wound and tissues and structures adjacent thereto so as to facilitate a realistic medical training tool. 
     In accordance with an embodiment of the invention, the wearable wound simulant includes a skin replica having the appearance of a particular region of the human body, examples including, but not limited to, a leg, arm, torso, or stomach, and at least one wound disposed along the skin replica. The skin replica further includes a plurality of bendable layers arranged to replicate visual and tactile properties of skin and at least one tear resistant layer comprised of a fabric material disposed between a pair of bendable layers. The tear resistant layers are less stretchable than the bendable layers so as to prevent the bendable layers from stretching beyond their failure threshold. 
     In other embodiments, the skin replica could include pigments to replicate a bruise or burn. 
     In yet other embodiments, the wound simulant could include an object having the visual and tactile properties of a bone with or without a fracture. 
     In still other embodiments, the wound simulant could include a fastener system comprised of a two-piece hook-and-loop device or a zipper to secure the wound simulant onto a user. 
     In further embodiments, the present invention could include elements which enhance functionality. Accordingly, the skin replica could be self-sealing so as to allow for the insertion of a needle or the like without compromising the integrity of the simulant. The wearable wound simulant could include one or more tubes, replicating the resiliency of vascular elements, disposed between a pair of tear resistant layers. The wearable wound simulant could include at least one reservoir disposed along or within a skin replica and capable of storing a fluid simulating blood or other body fluid. The reservoir and adjacent wound structure could produce the appearance of a bleeding wound either when pressure within the reservoir reaches a threshold value or when pressure is applied onto the wound. The wearable wound simulant could also include a penetration cavity which extends beyond the skin replica. The wearable wound simulant could also include an object representative of an internal organ that protrudes from a wound. 
     Several advantages are offered by the described invention. The invention facilitates visual, tactile, and functional aspects of a battlefield wound facilitating the diagnosis of injuries and implementation of treatments. The invention facilitates the simulation of various bleed conditions, including, but not limited to, gushing, spurting and seeping. The invention facilitates treatment of a wound including the insertion of a needle or the like, the probing of wounds, the packing of wounds, the compression of vascular elements to prevent or limit blood loss, and the replacement of dislodged organs and the like. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 REFERENCE NUMERALS 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 Skin replica 
               
               
                 2 
                 Highlight layer 
               
               
                 3 
                 Highlight layer 
               
               
                 4 
                 Base layer 
               
               
                 5 
                 Fabric layer 
               
               
                 6 
                 Backup layer 
               
               
                 7 
                 Depth layer 
               
               
                 8 
                 Pigment layer 
               
               
                 9 
                 Elastic material 
               
               
                 10 
                 Needle 
               
               
                 11 
                 Cavity 
               
               
                 12 
                 Bone replica 
               
               
                 13 
                 Cavity 
               
               
                 14 
                 Arm simulant 
               
               
                 15 
                 Fracture 
               
               
                 16 
                 Internal layer 
               
               
                 17 
                 Force 
               
               
                 18 
                 Elastic deflection 
               
               
                 19 
                 Leg simulant 
               
               
                 20 
                 Fastener system 
               
               
                 21 
                 Stitching 
               
               
                 22 
                 Arm simulant 
               
               
                 23 
                 Fastener system 
               
               
                 24 
                 Fabric layer 
               
               
                 25 
                 Supply tube 
               
               
                 26 
                 Wound 
               
               
                 27 
                 Resilient opening 
               
               
                 28 
                 Blood simulant 
               
               
                 29 
                 Supply tube network 
               
               
                 30 
                 Reservoir 
               
               
                 31 
                 Surface 
               
               
                 32 
                 Patch 
               
               
                 33 
                 Cavity 
               
               
                 34 
                 Torso simulant 
               
               
                 35 
                 Wound 
               
               
                 36 
                 Wound cavity 
               
               
                 37 
                 Stomach simulant 
               
               
                 38 
                 Wound 
               
               
                 39 
                 Object 
               
               
                 40 
                 Cavity 
               
               
                 41 
                 Fastener system 
               
               
                 42 
                 Seam 
               
               
                 43 
                 Leg 
               
               
                 44 
                 Thigh 
               
               
                 45 
                 Flap 
               
               
                 46 
                 Interior surface 
               
               
                   
               
             
          
         
       
     
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a cross-sectional perspective view illustrating construction of a skin replica in accordance with an embodiment of the present invention. 
         FIG. 2  is a cross-sectional perspective view illustrating construction of a skin replica with bruising effect in accordance with an embodiment of the present invention. 
         FIG. 3   a  is a top view illustrating the stretch behavior of an exemplary elastic material. 
         FIG. 3   b  is a top plan view illustrating the stretch behavior of a skin replica in accordance with the present invention. 
         FIG. 4  is cross-sectional perspective view illustrating the self-sealing behavior of a skin replica in accordance with an embodiment of the present invention. 
         FIG. 5   a  is a perspective view illustrating the attachment of a bone replica to a tear resistance fabric in accordance with a preferred embodiment of the present invention. 
         FIG. 5   b  is a perspective view with partial cross section illustrating attachment of the bone replica and tear resistant fabric layer shown in  FIG. 5   a  to a skin replica in accordance with an embodiment of the present invention. 
         FIG. 6   a  is a perspective view illustrating a plurality of cavities within a bone replica. 
         FIG. 6   b  is a perspective view with partial cross section illustrating attachment of the bone replica shown in  FIG. 6   a  to a skin replica in accordance with an embodiment of the present invention. 
         FIG. 7  is a partial sectional view illustrating a bone fracture within an arm simulant in accordance with an embodiment of the present invention. 
         FIG. 8   a  is a cross-sectional perspective view illustrating construction of a skin replica with optional internal layer in accordance with an embodiment of the present invention. 
         FIG. 8   b  is a cross-sectional perspective view illustrating the elastic behavior of the skin replica shown in  FIG. 8   a.    
         FIG. 9   a  is a side elevation view illustrating attachment of a leg simulant in accordance with a preferred embodiment of the present invention. 
         FIG. 9   b  is a top plan view illustrating attachment of hook-and-loop fasteners to a skin replica. 
         FIG. 9   c  is perspective view illustrating attached of hook-and-loop fasteners to a skin replica. 
         FIG. 10   a  is a side elevation view illustrating construction of an arm simulant with zipper mechanism in accordance with a preferred embodiment of the present invention. 
         FIG. 10   b  is a cross-sectional perspective view illustrating attachment of a zipper to a skin replica. 
         FIG. 11   a  is a cross-sectional perspective view illustrating attachment of a deformable tube within a skin replica in accordance with a preferred embodiment of the present invention. 
         FIG. 11   b  is a cross-sectional perspective view illustrating deflection of a deformable tube within a skin replica in response to an applied force. 
         FIG. 12   a  is a side elevation view illustrating an arm simulant with a plurality of seeping-type wounds in accordance with an embodiment of the present invention. 
         FIG. 12   b  is an enlarged view of the arm simulant shown in  FIG. 12   a  illustrating blood loss from seeping-type wounds. 
         FIG. 13  is a cross-sectional perspective view of the interior of an arm simulant illustrating a network of supply tubes and reservoirs in accordance with an embodiment of the present invention. 
         FIG. 14  is a cross-sectional perspective view illustrating construction of a skin replica with bleed structure in accordance with an embodiment of the present invention. 
         FIG. 15   a  is perspective view illustrating a torso simulant with a plurality of wounds in accordance with an embodiment of the present invention. 
         FIG. 15   b  is a cross-sectional perspective view illustrating a penetration cavity within a skin replica in accordance with an embodiment of the present invention. 
         FIG. 16   a  is a perspective view illustrating a wound with protruding viscera in accordance with an embodiment of the present invention. 
         FIG. 16   b  is a cross-sectional perspective view illustrating attachment of viscera to a skin replica. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is understood to include a multi-layered structure, referred to as a skin replica  1 , and at least one wound  26 ,  35 , or  38  disposed thereon, as described in detail herein. The present invention is described with specific reference to applications involving an arm, leg, torso, and stomach; however, it is understood that the present invention is likewise applicable to other regions of a human body. Wounds  26 ,  35 , or  38  are also understood to mean a structure representative of an injury caused by a penetration, impact, blast, fire, or other combat-related wound. The invention described herein is preferred to completely surround and cover the body region which it replicates. 
     Referring now to  FIG. 1 , one embodiment of the skin replica  1  is a multi-layered structure including a pair of highlight layers  2 ,  3 , a base layer  4 , a fabric layer  5 , and a backup layer  6  arranged and contacting in the order described. Highlight layers  2 ,  3 , base layer  4 , and backup layer  6  are each composed of one or more silicone-based polymers, either translucent or transparent, which are flexible, stretchable, compressible and resilient. Low durometer or soft silicones are preferred. The fabric layer  5  is a woven structure or the like, which is flexible, stretchable, and resilient, composed of natural or synthetic fibers, one example being polyester. 
     Referring now to  FIG. 2 , another embodiment of the skin replica  1  is a multi-layered structure including a pair of highlight layers  2 ,  3 , a depth layer  7 , a pigment layer  8 , a base layer  4 , a fabric layer  5 , and a backup layer  6  arranged and contacting in the order described. The highlight layers  2 ,  3  depth layer  7 , pigment layer  8 , base layer  4 , and backup layer  6  are each composed of one or more silicone-based polymers, either translucent or transparent, which are flexible, stretchable, compressible, and resilient. The fabric layer  5  is a woven structure or the like, which is flexible, stretchable, and resilient, composed of natural or synthetic fibers. 
     The color and overall appearance of human skin is the product of dermal layers with different translucent qualities, as well as, the visualization of veins, bruises, bleeding, and other structures below or within the dermal layers. The skin replica  1  replicates or approximates the visual characteristics of human skin via the layered arrangement of polymer layers, each including one or more pigment compositions. The visual characteristics of the highlight layers  2 ,  3 , base layer  4 , backup layer  5 , depth layer  7 , and/or pigment layer  8  interact to produce the color, translucence, and texture of human skin. 
     The highlight layers  2 ,  3  are the outermost or exterior layers of the skin replica  1 . One purpose of the highlight layers  2 ,  3  is to replicate the flesh tones of skin. Each highlight layer  2 ,  3  includes at least one pigment compound which replicates the appearance of flesh. For example, each highlight layer  2 ,  3  could be composed of a translucent silicone polymer with a thickness less than 1 millimeter loaded with a powdered pigment in a mass concentration of less than 1% by weight, however, other thicknesses and concentrations are possible. Pigments are understood to mean commercial powders readily available at an art supply shop or the like. 
     One purpose of the base layer  4  is to support the highlight layers  2 ,  3  and fabric layer  5 . The base layer  4  could be composed of a translucent silicone polymer with a thickness of approximately 2 millimeters having a pigment which approximates flesh tones in a mass concentration of less than 1% by weight, however, other thicknesses and concentrations are possible. 
     One purpose of the backup layer  6  is to further secure the fabric layer  5  to the base layer  4 . The backup layer  6  could be composed of a commercially available translucent silicone polymer with a thickness of at least 1 millimeter and optionally loaded with colored pigment, which approximates flesh tones, to a mass concentration of less than 1% by weight, however, other thicknesses and concentrations are possible. 
     One purpose of the depth layer  7  is to enhance the depth characteristics of the pigment layer  8  so as to give the appearance of an internal injury. The depth layer  7  could be composed of a translucent silicone polymer with a thickness of approximately 1.5 millimeters, although the thickness is application dependent, loaded with optional flesh tone colored pigments to a mass concentration of less than 1% by weight, however, other thicknesses and concentrations are possible. 
     One purpose of the pigment layer  8  is to replicate the appearance of an internal injury, examples including but not limited to bruising or bleeding. The pigment layer  8  could be composed of a translucent silicone polymer with a thickness from 1 to 2 millimeters and loaded with optional flesh colored pigments in a mass concentration of at least 3% by weight; however, other thicknesses and concentrations are possible. The intensity of the pigment layer  8  is inversely related to the thickness of the depth layer  7 , which is adjusted to achieve the desired appearance. 
     The fabric layer  5  prevents overstretching of the skin replica  1  beyond the threshold at which the skin replica  1  fails and ensures closure of punctures and/or holes along the skin replica  1 . The fabric layer  5  is preferred to be a woven structure or to have a plurality of holes therein to ensure impregnation by silicone polymers comprising the base layer  4  and backup layer  6 . The fabric layer  5  could be a translucent, transparent, or colored material which enhances the skin-like appearance of a skin replica  1 . 
     Referring now to  FIG. 3   a , a multi-layered elastic structure  9  is graphically represented in a stretched condition. Elastic structures  9  composed of silicone polymers and the like stretch until either a tear or delamination results. Failure occurs when the stretch exceeds the elastic limit of one or more layers in the structure. In the present invention, the fabric layer  5  constrains or limits the degree of stretch otherwise allowable along the structure, as graphically represented in  FIG. 3   b  for an exemplary skin replica  1 . Accordingly, the maximum stretch length of the fabric layer  5  should be less than the stretch length at which a failure would occur within one or more polymers comprising a skin replica  1 . 
     The insertion of a needle and intravenous line are critical to the treatment of battlefield wounds. Accordingly, it is desired for a skin replica  1  to allow a trainee to puncture the simulant without irreparably damaging the device. 
     Referring now to  FIG. 4 , an exemplary self-sealing skin replica  1  is shown before and after perforation by a needle  10 . The layered construction of polymers and fabric, as described herein, enables the skin replica  1  to deform when penetrated by a needle  10  so as to form a cavity  11 , much like the response of human tissues. Upon removal of the needle  10 , the elastic properties of the polymers and fabric cause the cavity  11  to collapse or close, much like human tissues, to nearly at least the original condition of the skin replica  1 . While subsequent stretching of the skin replica  1  could cause the cavity  11  to reopen in a limited fashion, the cavity  11  does not initiate a tear because of the constraining properties of the fabric layer  5 . Furthermore, the fabric layer  5  prevents punctures and tears from propagating along the skin replica  1 . 
     The following is exemplary of one method used to fabricate a skin replica  1 . Fabrication of a skin replica  1  includes the layered application of one or more silicone polymers and fabric sheets. One or more polymers with the same, similar, or different flexibility, stretchability, compressibility, and/or resiliency characteristics could be used to replicate the compressibility and elasticity of skin within a particular region of a body. The bond between two polymer layers is preferred to be a chemical or adhesive bond at least as strong as the weakest polymer. 
     First, liquid-based silicone polymers are blended and mixed with powdered pigments to achieve the desired balance between translucency and color. Next, a pigmented silicone polymer is applied via a brush onto a planar or non-planar mold, textured to replicate a body part, and cured at room temperature to form the first highlight layer  2 . The mold could include one or more structures which form a hole or cavity into one or more layers of the skin replica  1  to replicate tissues compromise d by a projectile, shrapnel, blast, burn, or the like. Next, a pigmented silicone polymer is applied onto the first highlight layer  2  and cured at room temperature to form a second highlight layer  3 . Next, a pigmented silicone polymer is applied onto the second highlight layer  3  forming a base layer  4  and thereafter a fabric layer  5  is applied to the base layer  4  before the base layer  4  cures. Thereafter, the base layer  4  is cured at room temperature. Next, a pigmented silicone polymer is applied onto the fabric layer  5  so as to fully impregnate the fabric with polymer. Thereafter, the polymer is cured at room temperature. 
     In some embodiments, a depth layer  7  and pigment layer  8  may be required. The depth layer  7  is applied as a layer of pigmented silicone polymer to the second highlight layer  3  and thereafter cured at room temperature. Next, a pigmented silicone polymer is applied to the depth layer  7  to form a pigment layer  8  and cured at room temperature. Thereafter, base layer  4 , fabric layer  5 , and backup layer  6  are applied as described herein. 
     After the last applied layer is cured, the skin replica  1  is removed from the mold and edges are trimmed with a knife or shears to remove excess materials. Finally, an optional seam is cut into the skin replica  1 . In some embodiments, the layup of layers could be performed along a planar-shaped mold, thus avoiding the cutting step to form a seam. 
     In some embodiments, a bone replica  12  could be required to simulate a wound  26 . Referring now to  FIG. 5   a , a bone replica  12 , exemplary of a bone which has fractured or otherwise penetrated the tissues adjacent to a wound  26 , is shown attached to a fabric layer  5 . The bond replica  12  could be composed of a hard cast resin, one example being urethane, shaped to replicate the appearance, pigmented to replicate the color as described herein, and composed of a composition to replicate the hardness of a bone. In some embodiments, the bone replica  12  is disposed along and/or about a portion of a fabric layer  5  and cured so as to bond or mechanically attach the two elements. Thereafter, the fabric layer  5  with attached bone replica  12  is applied between a base layer  4  and backup layer  6 , as described herein, so as to mechanically lock the bone replica  12  to the skin replica  1 . Further, the bone replica  12  could protrude from a skin replica  1 , as represented in  FIG. 5   b , within a cavity, hole, or opening along the skin replica  1  representative of a penetration, blast, or impact type wound  26 . 
     Referring now to  FIG. 6   a , other embodiments of the invention could include a bone replica  12  having one or more cavities  13  along the bone structure. Cavities  13  could be molded into the bone replica  12  during fabrication or mechanically drilled into the item after the resin structure has properly cured. Cavities  13  enable attachment of the bone replica  12  to the skin replica  1 , as represented in  FIG. 6   b . In these embodiments, the bone replica  12  is positioned within one or more silicone polymer layers prior to cure so as to allow the polymer to fill each cavity  13 . Thereafter, the polymer is cured so as to mechanically lock the bone replica  12  onto the skin replica  1 . 
     Referring now to  FIG. 7 , an exemplary arm simulant  14  is shown including two or more bone replicas  12  enclosed within, rather than protruding from, a skin replica  1 . One or more bone replicas  12  could include a fracture  15  or break exemplary of an internal injury. The skin replica  1  is composed of silicone polymers which mimic the tissues about a fracture  15  so as to allow a trainee to develop the skills required to identify and diagnose a concealed bone injury. 
     Referring now to  FIG. 8   a , it might be advantageous in some embodiments to include an internal layer  16  within a skin replica  1  to approximate the properties of fat, muscle, bones, or internal organs. The internal layer  16  could be composed of a silicone polymer which is softer or harder and/or less or more compressible than the highlight layers  2 ,  3 , base layer  4 , backup layer  6 , depth layer  7 , and/or pigment layer  8 , which otherwise comprise a skin replica  1 . For example, the internal layer  16  could be positioned within the skin replica  1  so that the uppermost layers, namely, highlight layers  2 ,  3 , slough or exhibit an elastic deflection  18  much like skin does over muscle when a force  17  is applied thereto. In preferred embodiments, the internal layer  16  should be enclosed within a base layer  4  and substantially parallel to the highlight layers  2 ,  3 , as represented in  FIG. 8   b , although other arrangements are possible. 
     Referring now to  FIG. 9   a , a leg simulant  19  is shown including a wound  26  at one end and a pair of flaps  45  disposed at another end. Flaps  45  could be composed of one or more layers of a skin replica  1  along the leg simulant  19 . The flaps  45  extend from the leg simulant  19  so as to encircle the body part onto which the simulant is applied. A fastener system  20  is attached to the flaps  45 , as represented in  FIGS. 9   b  and  9   c . In preferred embodiments, the fastener system  20  could include a two piece hook-and-loop device, one example being Velcro®, so that the loop component of the system is attached to one flap  45  and the hook component is attached to the other flap  45 . The fastener system  20  could be attached to the flaps  45  via stitching  21 , as represented in  FIGS. 9   b  and  9   c . In preferred embodiment, the stitching  21  is placed about the perimeter of each fastener element and along two diagonals in an intersecting pattern. The leg simulant  19  could be attached to an actor&#39;s leg  43  by encircling the actor&#39;s thigh  44  with the flaps  45  and securing the two-piece fastener system  20  thereto, as represented in  FIG. 9   a . The described attachment structure is likewise applicable to other simulants and replicas described herein. 
     Referring now to  FIGS. 10   a  and  10   b , a closable fastener system  23 , one example being a zipper, could be provided along the length of an arm simulant  22  to secure it onto an actor. The two-piece fastener system  23  could be attached to the arm simulant  22  by embedding a pair of fabric layers  24  within a skin replica  1 , along the arm simulant  22 , about a seam  42 . For example, the individual pieces of the fastener system  23  could be adhesively bonded or mechanically attached via stitching to separate fabric layers  24 . Thereafter, the fabric layers  24  could be embedded between two polymer layers as described herein. A cover or the like could be placed along the length of the fastener system  23  to conceal it from view. The described attachment structure is likewise applicable to other simulants and replicas described herein. 
     Referring now to  FIGS. 11   a  and  11   b , a supply tube  25 , replicating the functionality of a vein, artery, or other vascular structure, could be embedded within a skin replica  1 . The incorporation of tubes within a multi-layered polymer structure is problematic in that tubes do not bond well with polymers. In the present invention, two fabric layers  5  are disposed about a supply tube  25 . The fabric layers  5  are impregnated with a silicone polymer composition so as to bond with the fabric layers  5 , rather than directly with the supply tube  25 . In preferred embodiments, the supply tube  25  is a compressible, translucent tube disposed between a base layer  4  and a backup layer  6  so as to allow deflection thereof when a force  17  is applied by a tourniquet or the like, as represented in  FIG. 11   b . The supply tube  25  could also include coloring consistent with human tissues. 
     Referring now to  FIGS. 12   a  and  12   b , an arm simulant  14  is shown including a plurality of resilient openings  27  replicating a wound from which a blood simulant  28  seeps, rather than spurts or gushes. Each resilient opening  27  is comprised of a slit or pinhole which traverses some or all layers within a skin replica  1 . The self-sealing property of the skin replica  1  could prevent the blood simulant  28  from passing through the resilient openings  27  under certain conditions. 
     Referring now to  FIG. 13 , a plurality of reservoirs  30  are shown attached to and communicating with a supply tube network  29  along an exemplary arm simulant  22 . One end of the supply tube network  29  is attached to a manual or electric pump or the like so as to communicate blood simulant  28  from a container residing within or separate from the arm simulant  22 . 
     A reservoir  30  is understood to be a cavity capable of temporarily storing a blood simulant  28 . Each reservoir  30  is disposed along the structure of the skin replica  1  so as to communicate with one or more resilient openings  27 . Reservoirs  30  are formed by placing a silicone patch  32  or the like, preferably with flesh tone pigments, onto the base layer  4  or backup layer  6  of a skin replica  1  and at least one tube within a supply tube network  29 . Thereafter, the periphery of each patch  32  is bonded to the base layer  4  or backup layer  6  and supply tube network  29  via a silicone resin, including optional flesh tone pigments. 
     Referring now to  FIG. 14 , the cavity  33  within a reservoir  30  is shown filled with a blood simulant  28  so that the resilient openings  27  are expanded. The blood simulant  28  passes through or flows from one or more resilient openings  27  when either the pressure exerted by the blood simulant  28  exceeds a threshold value or an actor or trainee applies a force onto the surface  31  adjacent to a resilient opening  27  to negate the self-sealing properties of the skin replica  1 . 
     Referring now to  FIGS. 15   a  and  15   b , a torso simulant  34  with fastener system  20  is shown including a plurality of wounds  35 . One or more wounds  35  could include a wound cavity  36  which traverses and extends beyond the skin replica  1 . Wound cavities  36  should be sufficiently large and/or expandable so as to allow for the insertion of a finger or probe by a trainee or gauze or other materials used to treat a wound. In preferred embodiments, two wound cavities  36  could be arranged to replicate the entry and exit points produced by a projectile and attached to a supply tube network  29 , as described herein. The wound cavity  36  could be fabricated via a complimentary structure residing along a mold allowing for the fabrication of a multi-layer structure, as described herein for a skin replica  1 . The mold could be textured so that the wound cavity  36  has the tactile properties associated with a gunshot wound or the like. In some embodiments, a fabric layer  5  could be applied to the interior surface  46  of the skin replica  1  to further resist punctures which might result from probing and packing of a wound cavity  36 . 
     Referring now to  FIGS. 16   a  and  16   b , a stomach simulant  37  with fastener system  20  is shown with an object  39  extending from a wound  38 . The object  39  could represent an internal organ, one example being an intestine, or tissues which are dislodged from a human body. The object  39  could be composed of a pigmented silicone resin replicating the shape, visual, and tactile properties of an internal organ or tissues. The object  39  could be attached to the skin replica  1  via a fastener system  41 , one example being a two-piece hook-and-loop device, housed with a cavity  40 , as represented in  FIG. 16   b . In preferred embodiments, the cavity  40  is could be sufficiently voluminous so as to allow for the reinsertion of the object  39  into the skin replica  1  by a trainee. In yet other embodiments, the cavity  40  or object  39  could be attached to a supply tube network  29  and include one or more bleed points, as described herein. 
     The description above indicates that a great degree of flexibility is offered in terms of the present invention. Although various embodiments have been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.