1. Field of the Invention
The invention relates to fabric based body armor. More specifically, the invention relates to fabric based body armor capable of defeating multiple threats.
2. Background of the Invention
There has long been the need for body armor designed for resistance to penetration from sharp pointed implements such as ice picks, awls, other man made improvised devices primarily designed for stabbing and single and double edged blades for both stabbing and slashing into the body causing severe injury, disability or even death. Prior penetration resistant armors provide good levels of protection, but allow some penetration through the armor. These armors do not allow penetration by sharp pointed implements far enough into the torso cavity to engage and perforate any major organs such that the penetration would be fatal. The major organs that are most commonly identified as requiring protection are the heart, liver, kidneys, spleen and sometimes the spine. An attack from the posterior requires less penetration from the sharpened implement to damage a major organ. This is especially true in the case of the spine. Additionally, there are other vital elements of the body that, if penetrated, would result in a fatality. These areas are also often covered by body armor. These additional areas include the neck.
Current penetration test protocol and procedural tests generally allow for some level of penetration. These levels of penetration allow up to one inch of the implement to completely penetrate the body armor. This degree of penetration would be catastrophic if the penetration were through a major artery or the spinal column. A penetration, tearing through the arterial walls can cause profuse bleeding that is not easily stopped. A penetration into the spinal column can cause partial or complete paralysis, severe nerve damage and severe bleeding if the arteries within the spinal column are penetrated.
Therefore, there is a need for a penetration resistant body armor that precludes penetration in order to protect those areas that are in the direct path of a penetrating implement thus preventing severe and/or fatal injury to the wearer.
The invention is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one.
Stab resistant body armor is designed to do one primary function, which is to stop pointed or sharp object penetration (stab resistance) through a process relying on the tensile strength coupled with specific cross over pick counts of component fabrics that resist penetration through the weave or through the material itself by a “Cover Factor” and/or “Fabric Tightness Factor.” Cover Factor is a term used to describe the density of the weave of a fabric. This density is defined as the value of the geometry of the weave calculated with the percentage of gross surface area of the fabric that is actually covered by the yarns of the fabric (not the voids between cross over points). Weave styles and their resultant pick counts or cross over points vary widely. It is very possible to have a low maximum cover factor even though the weave count is high or the fabric is woven tightly. The fabric tightness factor is a measure of the tightness of a specific fabric weave as compared to maximum tightness of the cover factor or the actual full material covering over a given fabric surface. These two factor equations are from the text (Weaving: Conversion of Yarns to Fabric, Lord and Mohamed, published by Merrow (1982), pages 141-143).
Dw=width of warp yarn in the fabric
Df=width of fill yarn in the fabric
Pw—pitch of warp yarns (ends per unit length)
Pf=pitch of fill yarns
Exemplary fabrics include aramid fabrics with high tensile strengths and high resistance to penetration. This resistance to penetration comes from a combination of the aramid fabric's fiber tensile strength, elongation of yield, and selected pick count. Pick count is a measure of the number of threads of fiber in a given area of fabric. The greater the pick count the greater the number of threads in a given area the fabric has. A fabric with a high pick count may have a greater resistance to penetration than a fabric with an identical thread but a lower pick count.
In adjusting the denier and pick count of a fabric, care must be given to not place too may fibers with too high a denier in a given area. As denier increases, the diameter of the fiber increases. Increasing the denier of a fiber without reducing the pick count of the fabric may lead to crimping. Crimping occurs when the fibers are so tightly packed together at crossover points the fibers cannot elongate. When crimping occurs there is no benefit gained from the fiber's ability to stretch. Thus, too high a denier combined with too high a pick count results in crimping and reduced efficiency of the fabric.
Similar fabric materials with different deniers and pick counts effectively make different material. This is because they will have different mechanical properties. Higher denier means there is more of the fiber per length of thread. This additional material gives the thread greater tensile strength. Greater tensile strength gives the fabric greater resistance to penetration. Higher pick counts mean there are more threads per area to be struck by the implement. These additional threads in higher pick count materials add their tensile strength to the resistance to penetration of the fabric. Due to the above mentioned relation between fiber denier and pick count, a higher denier fiber with a lower pick count may still have the same strength, but increasing the denier of the thread to increase tensile strength will cause the weight of fabric to increase.
There are other elements that have a significant effect upon the capability or incapability of a textile to preclude penetration. The elements may overcome even the best cover factors with or without the combined ratio of fabric tightness factors. These elements are related to the weapon itself and the methods of deployment.
There are three primary characteristics of a weapon and its use that affect its capability to penetrate an object:
1. size and shape
2. hardness
3. energy or amount of deliverable force applied to the weapon to drive its penetration.
Sharp pointed and round objects such as an awl or ice pick have very small pointed tips with minimal surface area to be resisted by a textile fabric. This eliminates the need for the implement to forcibly break the fabric fibers within the threads. The implement merely pushes the threads aside and slips through either the openings surrounding the weave crimp or through the fabric itself. Rigid plates, platelets, or resin impregnations aid in eliminating this type of penetration, and aid in single or double edged blade resistance. However, garments using these structures are heavy, less pliable and less comfortable to perform daily tasks in, for the wearer than purely fabric garments.
The
The National Institute for Justice (NIJ) has developed a standard for characterizing the stab resistance of personal body armor labeled NIJ Standard 0115.00. This standard specifies the minimum performance requirements for body armor that is resistant to a typical attack using a pointed or edged weapon. The highest level of protection defined by the NIJ 0115.00 includes a first energy level attack called “E1” and a second energy level attack “E2”. At level E1 a maximum blade or spike penetration of seven millimeters is allowed. At level E2 a maximum blade or spike penetration of twenty millimeters is allowed. The strike energy of the E1 threat is forty three Joules and the strike energy of the E2 threat is sixty five Joules. The NIJ 0115.00 test of a stab resistant garment includes an attack perpendicular to the plane of the garment (zero degree from center attack) and a forty five degree angled attack from the plane of the garment.
Further reference will now be made to the drawings. In the following drawings, like structures are provided with like reference designations. In order to show the structure of the invention more clearly, the drawings included herein are diagrammatic representations of the indicated structures. Thus, the actual appearance of the fabricated structures, for example, in a photograph, may appear different while still incorporating the essential structures of the invention. Moreover, the drawings show only the structures necessary to understand the invention. Additional structures known in the art have not been included to maintain the clarity of the drawings.
In one embodiment, protective sleeve 202 is a nylon fabric. The nylon fabric is composed of 200 to 400 denier material. The nylon protective sleeve 202 protects the enveloped layers from environmental factors such as direct sunlight that may adversely affect the strength or resistance properties of the fabrics in the enveloped layers. In one embodiment, the nylon sleeve 202 is treated to be water resistant. In another embodiment, the protective sleeve 202 is a Cordura® fabric, such as 500 denier Cordura® manufactured by DuPont® of Wilmington, Del. A protective sleeve 202 manufactured from Cordura® provides additional protection to the enveloped layers from heat and fire as well as ripping and tearing. In another embodiment, other fabrics with similar protective qualities are used to manufacture the protective sleeve 202.
In one embodiment, inner layer 206 includes multiple plies of penetration resistant fabric. The inner layer 206 includes at least two plies. In one embodiment, the inner layer 206 includes approximately five plies. The plies of the inner layer 206 are quilted together using diagonal cross-stitching 306 and perimeter stitching 308 using aramid thread in the same manner as the outer layer 204.
In one embodiment, the plies of the outer 204 and inner 206 layers are an aramid textile, (e.g., Kevlar® Correctional including Kevlar® 159, 200, manufactured by DuPont®) with a plain weave, a warp count of seventy, a fill count of seventy, a nominal weight of 3.90 ounces per square yard, a nominal thickness of 0.18 inches, breaking strength in the warp of approximately 385 pounds per square inch, and in the fill of approximately 530 pounds per square inch. In another embodiment, other textile fabrics are used in place of or in combination with Kevlar® Correctional™. The outer layer 204 and inner layer 206 can be constructed with any fabric that exhibits sufficient tensile strength, elongation, cover factor, weave tightness or encapsulation of fibers or threads to preclude penetration of an implement through the front panel 200 of the garment. A combination of fabrics can be used to resist specific threats. For example, to resist single and double edged blades a fabric including steel yarn, having a satin weave with a nominal thickness of 0.3 mm to 0.50 mm, a weight range of from 620 grams per square meter to 2005 grams per square meter, a nominal fiber diameter of twelve micrometers+−three micrometers, with a warp count from twenty-five to fifty per inch and a weft count from twenty to fifty per inch can be used. Other textile fabrics and compositions that are suitable include but are not limited to aramids, para-aramids, polyethylene composite encapsulated fibers with zero degree and ninety degree orientations, resin impregnated aramids and coated aramids. Trade names commonly associated with these fabrics include but are not limited to TurtleSkin® Diamond coat™, TurtleSkin® Palm master™, TurtleSkin® Flex™, and TurtleSkin® Sport™, manufactured by Warwick Mills, Inc of New Ipswich, N.H.; Spectra Shield®, Spectra® Flex™, Spectra Shield® plus, Gold flex®, and Gold Shield®, manufactured by Allied Signal, Inc. Petersburg, Va.; Dyneema UD series unidirectional sheets including UD-SB21, UD-SB31, UD75-HB2, and UD-HB-25, manufactured by DSM High Performance Fibers, B.V. Netherlands; Kevlar® woven fabrics manufactured for weaving by DuPont® Fibers Kevlar® Products, Wilmington, Del.; Spectra® woven fabrics manufactured by Allied Signal, Inc. Petersburg, Va.; and PBO Zylon® manufactured for weaving yarns; or fabrics by Toyobo, Tokyo Japan, licensed from Dow Chemical, Inc. Midland, Mich. In addition, some lighter and heavier textiles using carbon fiber, E glass and S2 glass hybrids could be used. Hybridization of various materials improves resistance to a broader range of threats currently in use or not known at this time. One of ordinary skill in the art would recognize however that with adequate notice given to denier, pick count and elongation of failure, various materials might be substituted for the materials mentioned above.
In one embodiment, the front panel 200 illustrated in
In one embodiment, additional layers (e.g., a third and forth layer, etc.) are attached to the inner layer 206 and outer layer 204 by the bar tacks 302 and 304. Additional layers aid in the reduction of penetration with increased weight. This alternating stitched and freeplay structure precludes penetration through the garment. This structure of layers with stitched plies and free play between layers defeats NIJ E2 threats including single and double edged blades. Edged blades cut and slice through materials weakening their structure, which aids in penetration of the materials. Loose non stitched plies of fabric are effective against blades because they allow the individual plies to slip and to resist penetration by reducing the tightness of a layer. However, once the plies reach a critical point of elongation they have less capability individually to resist the blade cutting through them. Thus, stitching that is overly tight aids an edged blade in slicing and cutting through a fabric. The alternation of the stitched layers with free play allowed by the bar tacked layers effectively prevents penetration by applying resistance, releasing resistance and then reapplying it through stretching and compression cycles of the fabric's ability to flex and rebound when configured in this manner.
Table I demonstrates the resistance capacity of one embodiment including two layers of Kevlar® Correctional™ material in a nylon envelope. The first layer having 17 plies of Kevlar® Correctional™ and the second layer having 5 plies of Kevlar® Correctional™. This embodiment, does not allow any penetration of the garment by a spike driven at an NIJ E2 level. The NIJ 0115.00 standard allows a seven millimeter penetration for an E1 threat and twenty millimeters for an E2 threat. This test also requires the test specimen to be tested at a zero degree and forty five degree angle of impact. A forty five degree angle of attack is likely to cause increased crossover point slippage by implement points, thereby aiding in the penetration of a tested garment.
In one embodiment, the garment is lighter than other penetration resistant garments manufactured from the same materials using other standard garment structures. The garment is also softer, thinner, and much more pliable or flexible.
In one embodiment, the weight of the garment is 1.75 pounds for a male or female garment with 22 plies (17 plies in a first layer and 5 plies in a second layer) in two layers of Kevlar® Correctional™ material. The garment has a thickness of 0.196 inches, including a nylon sleeve 202, an outer layer 204 and inner layer 206. The garment including outer sleeve and two layers weighs 9.52 ounces per square foot of protected area.
In another embodiment, garments composed of plies of aramid fabrics have a weight in the range of 7.56 ounces to 8.42 ounce per square foot. These embodiments included two layers of aramid fabrics and prevent any penetration by an E2 spike implement threat. In another embodiment, layers having aramid fabrics and at least one steel mesh material including steel yarn have a weight in the range of 10.21 ounces to 13.54 ounces per square foot. These embodiments can prevent the penetration of an E2 spike or blade threat.
One embodiment of the garment includes a collar at the neck. The collar is a three inch collar that is stitched to the garment by an aramid thread or similar thread. The seam attaching the collar underlaps the neck collar by 1 inch into the neck region of the garment. This underlapping prevents a failure point along the attachment seam. The collar has similar layer structure to the front or back panels. In one embodiment, a two-inch quilting pattern is used. The neck collar prevents E2 threats from penetrating the garment including zero degree and forty five degree attacks to the neck.
In one embodiment, the garment includes a carrier garment that holds the sleeved layers of protective fabric. Carrier garments include vests, jackets, coats and similar garments. In one embodiment, the carrier garment includes dart seams to form a cupped region. This embodiment improves the fit and protection for a female user. Dart seams are aligned across plies, layers, the enveloped sleeve and the carrier garment such that the folds made in forming the dart seams are made in alternating directions in adjacent material to prevent a bunching of material. This alternating of the dart seams reduces the stiffness of the garment and prevents complete penetration by an E2 threat at the dart seam.
In the preceding detailed description, the invention is described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the claims. The specification and drawings are; accordingly, to be regarded in an illustrative rather than a restrictive sense.
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