Patent Grant
8549803
The present invention generally relates to anti-ballistic and penetration resistant structures, such as panels, bulkheads, and doors.
In the accompanying drawings:
The instant invention is described more fully hereinafter with reference to the accompanying drawings and/or photographs, in which one or more exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be operative, enabling, and complete. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention. Moreover, many embodiments, such as adaptations, variations, modifications, and equivalent arrangements, will be implicitly disclosed by the embodiments described herein and fall within the scope of the present invention.
Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. Unless otherwise expressly defined herein, such terms are intended to be given their broad ordinary and customary meaning not inconsistent with that applicable in the relevant industry and without restriction to any specific embodiment hereinafter described. As used herein, the article “a” is intended to include one or more items. Where only one item is intended, the term “one”, “single”, or similar language is used. When used herein to join a list of items, the term “or” denotes at least one of the items, but does not exclude a plurality of items of the list.
For exemplary methods or processes of the invention, the sequence and/or arrangement of steps described herein are illustrative and not restrictive. Accordingly, it should be understood that, although steps of various processes or methods may be shown and described as being in a sequence or temporal arrangement, the steps of any such processes or methods are not limited to being carried out in any particular sequence or arrangement, absent an indication otherwise. Indeed, the steps in such processes or methods generally may be carried out in various different sequences and arrangements while still falling within the scope of the present invention.
Additionally, any references to advantages, benefits, unexpected results, or operability of the present invention are not intended as an affirmation that the invention has been previously reduced to practice or that any testing has been performed. Likewise, unless stated otherwise, use of verbs in the past tense (present perfect or preterit) is not intended to indicate or imply that the invention has been previously reduced to practice or that any testing has been performed.
Depicted in
The armored panel 30 in overview comprises a structural portion 31 made of a structural core 32 enclosed by rigid inner and outer core skins 33 and 34. Panel 30 further comprises a ballistic portion 41 consisting of a ballistic composite element 42 enclosed by inner and outer ballistic skins 43 and 44. The structural portion 31 is adhered to the ballistic portion 41 using a compatible resin or adhesive. In one embodiment of panel 30 the structural portion accounts for more than half the total thickness of the panel. For example, an exemplary panel 30 may comprise a structural portion 31 approximately 0.75 inches thick combined with a ballistic portion 41 approximately 0.35 inches thick.
The structural core 32 serves in part as a structural element of the structural portion 31, stabilizing the core skins 33, 34, and resisting the compression and shear loads imparted to the core when the panel undergoes bending or deflection. In one embodiment the physical attributes of the core material include light weight, high rigidity in the z (panel thickness) direction, and good shear strength in the x-y plane. A wide array of materials may be utilized to meet the structural needs of a core material, such as for example polymeric foam materials including Rohacell® structural foam sold by Evonik Industries, balsa wood, and various engineered structures known as honeycomb. Honeycomb is a flexible or rigid structural material that comprises a plurality of closely packed geometric cells that together form a lightweight honeycomb-shaped structure having high specific stiffness, high specific strength, and energy-absorbing characteristics. The geometric shape of honeycomb cells forming a structural core 32 may be any regular shape such as square and hexagonal, or alternatively over-expanded structures of various geometric shapes. Also suitable are reinforced honeycomb and other regular or irregular cellular frameworks.
The cells forming a honeycomb structural core 32 may be fabricated from a variety of rigid and flexible materials. For example, the cells may be formed from an aramid (aromatic polyamide) material such as Nomex®, a flame retardant meta-aramid material; Korex®, a high-strength para-aramid paper material; or Kevlar® aramid fiber honeycomb, each manufactured by E.I. duPont de Nemours and Company of Wilmington, Del. Other suitable materials non-exclusively include metals, such as aluminum, metal alloys, carbon, fiberglass, thermoplastic materials, such as polyurethane, and other materials conventionally known by those in the art for the formation of such honeycomb-shaped structures.
Each grade of honeycomb is characterized by a number of factors, including the type and strength of the honeycomb material, cell configuration, cell size and frequency, alloy and foil gauge (if an aluminum honeycomb), and density. In one exemplary embodiment, structural core 32 comprises aluminum honeycomb with cell sizes in the range of 1/16 in. to ¼ inch, and with cell wall thickness (“foil gauge”) in the range of about 0.001 in. to 0.005 inches. In one specific embodiment the structural core 32 is a 5056 aluminum alloy honeycomb with ⅛ in. cells of 0.002 in. foil gauge, approximately 0.75 in. thick, sold by Plascore Incorporated under the product designation PAMG-XR1-8.1-1/8-5056.
Core skins 33, 34 are selected from a suitably high-tensile strength material for providing strength and rigidity. In one embodiment the core skin has a tensile strength of at least 40,000 pounds per square inch, high toughness, a favorable strength-to-weight ratio, and is compatible with the resin system and other materials used in the structural core 32. Suitable materials include fiberglass woven material in 18, 20, or 22 oz. (ounce per square yard) weights and various S-glass or 7781 E-glass fabrics, such as phenolic resin prepreg material. High strength fibers such as aramid or carbon fibers, and metals such as aluminum or stainless steel may be used for core skins 33 or 34 as well. For fabric embodiments the skins may be cross plied layers of unidirectional fabric or layers of woven material. Resins used to impregnate material layers may be flame-resistant to enhance the overall fire resistance of armored panel 30. In one exemplary embodiment the core skins comprise a unidirectional cross-plied (0/90) fiberglass prepreg face sheet with a flame retardant epoxy matrix, sold by J D Lincoln of Costa Mesa Calif. under the product name Fiberply L-201.
The core skins 33, 34 may be bonded to the structural core 32 using a high strength structural adhesive material such as a urethane, thermosetting adhesive, or various epoxies. In one exemplary embodiment the adhesive is a self-priming, polyether based, low modulus aliphatic thermoplastic polyurethane film/sheet product sold by Deerfield Urethane under the name A4700. In another embodiment, the adhesive is a thermosetting epoxy structural adhesive in film form, such as Scotch Weld Structural Adhesive Film AF 163-2 sold by 3M, or NB 101 epoxy film sold by Newport Adhesives and Composites Inc. of Irvine Calif. Using film type thermosetting adhesives, the panel may be assembled with the film adhesive between the core and skins, and the entire assembly then heat cured using the manufacturer prescribed temperature and time.
Like the described embodiments of the structural portion 31, ballistic portion 41 of armored panel 30 may be a sandwich structure comprising a ballistic core 42 between inner and outer ballistic skins 43, 44. For example, ballistic core 42 may be a multi-layer stack of unidirectional fiber ballistic fabric layers, consolidated under heat and pressure into a rigid or semi-rigid composite. The fabric layers may be any high-tensile strength fabric such as are known for making ballistic resistant articles. Suitable commercially available products include fabrics made from aramid fibers such as those sold under the trademark Kevlar®, fabrics made from ultra-high molecular weight polyethylene fibers such as those sold under the trademarks Spectra® and Dyneema®, and fabrics made from polyphehylenebenzobisoxazole (PBO) fibers such as those sold under the trade name Zylon®. As used in this application, the terms “high performance fiber”, “high strength fibers”, and “ballistic fibers” refers to fibers having a tensile strength greater than 7 grams per denier.
In one exemplary process of fabricating a ballistic core 42, a bonding film is applied to a uniform flattened layer of parallel fibers to form a stable unidirectional sheet. Layers of the unidirectional fabric are stacked in a cross plied arrangement, such as so-called 0/90 degree cross ply, or any other angular relationship or combination of angular relationships. The stacked layers are consolidated into a semi-rigid ballistic composite under heat and pressure. The bonding film may be selected to permit flexure of the fabric layers when struck by a ballistic object.
Enhanced anti-ballistic characteristics may be obtained while optimizing use of materials in the composite. Specifically, it has been determined that a lightweight ballistic composite can be constructed of high performance ballistic fibers in the absence of adhesive resins and conventional matrix materials to hold the fibers together. By omitting the resin, the arrays of fibers directly contact each other, instead of being encapsulated and therefore separated from each other by the resin. For example, an ultra-thin film may be used both to cover the cross-plied arrays and to hold the arrays to each other. In one exemplary embodiment the percentage by weight of high strength fibers in the ballistic composite 42 is at least 80% of the total weight of the ballistic composite.
In one particular embodiment of a process for creating a ballistic composite 42, a plurality of bundles of untwisted unidirectional high performance fibers are formed into an array having a predetermined uniform number of bundles per inch of width. A bonding film or scrim is continuously laminated to one or both sides of the array of fiber bundles with heat and pressure to produce a stabilized array. The film or scrim may be a dry thermoplastic material in the form of an extremely thin, on the order of 0.0003 inches thick, fibrous non-woven film. Suitable commercially available thin fibrous thermoplastic film is sold by Spunfab Adhesive Fabrics, located in Cuyahoga Falls, Ohio. The laminating process may be performed using a laminating machine comprising a heating section, a nip roller, and a cooling section.
Two layers, or plies, of the stabilized unidirectional fiber arrays are laminated together with heat and pressure to form a cross-ply laminate in which the fiber directions of the two layers are an angle to one another. The cross-ply laminating process may include application of an additional thin film to the outside of the cross-ply laminate. Multiple layers of the cross ply laminate are stacked and bonded together under further heat and pressure to produce the ballistic composite 42. The bonding of the stacked laminates may be carried out using for example a heated mechanical press, or through a vacuum bag process performed in an oven or autoclave.
In the above described embodiments of laminating and bonding processes the bonding film material may coat the exterior surfaces of the individual fiber bundles of an array, but will not penetrate into the fiber bundles or coat the individual fibers and filaments. With the fiber bundles coated by the film on the outside surface only, the integral structure of parallel, closely bunched filaments and fibers remains intact, and intimate contact between the closely bunched filaments and fibers remains. In some cases the film may not even coat the entire outer surface of the fiber bundles, but only to a sufficient degree to properly bond adjacent arrays together.
The number of layers of ballistic material may be selected in proportion to the weight, breaking strength, and dynamic performance of the individual layers. When using aramid fiber materials as described herein, there may be for example anywhere from about 10 to 50 layers of fabric material. In one embodiment the ballistic composite 42 comprises about 30 layers of 0/90 cross plied T-Flex® ballistic fabric sold by Tech Fiber of Tempe, Ariz. Additional methods of fabricating a lightweight high strength fiber composite suitable for use in the ballistic material portions of the present invention are disclosed in U.S. Pat. Nos. 5,437,905, 5,635,288; 5,935,678; 6,651,543; each of which is hereby incorporated by reference.
Ballistic skins 43, 44 add strength to the ballistic composite 42 as well as participate in arresting the progress of a projectile striking the panel 30. Outer ballistic skin 44 in particular may additionally serve as a durability layer, with sufficient stiffness and toughness properties to withstand normal wear and tear for a particular application. Ballistic skins 43, 44 may comprise a rigid composite material such as fiberglass or any of the composite structural materials previously discussed in reference to the core skins 33, 34. For example the ballistic skins 43, 44 may be pre-preg fiberglass sheets that are adhered to the ballistic composite 42 during the same hot press process used to consolidate the composite layers. Additional adhesive may be used, or bonding could rely entirely on the resins contained in the pre-preg and the film attached to the ballistic fabric layers. In one particular embodiment the face skins 43, 44 are made of a 7781 E-glass solution coated epoxy pre-preg sold under the trade name L-530 by J. D. Lincoln inc. of Costa Mesa Calif.
The armored panel 30 is assembled by bonding the structural portion 31 to the ballistic portion 41 using a suitable adhesive. Preferred adhesive qualities for joining the panels include good flexibility for ballistic performance, and relatively low temperature application to avoid loosening of adhesives used in construction of the structural and ballistic portions. In one exemplary embodiment the bond is achieved with an adhesive transfer tape sold under the trade name VHB F9469PC by 3M Corporation of Minneapolis Minn. Alternatively, all of the layers comprising the ballistic and structural portions may be assembled and bonded at one time.
An armored assembly may further comprise a movable hatch or door within a larger panel or door, such as for example a decompression hatch located in a door or bulkhead of an aircraft.
A threat side seam 251 is defined between the outer edge of perimeter flange 245 and the recessed edge of ballistic portion 241 of panel 201. In one embodiment an armor plate 243 is embedded in the structural portion 231 of panel 201 beneath seam 251. The armor plate 243 is overlapped by both the ballistic portion 241 of the panel 201, and the perimeter flange 245 extending from the edge of hatch 202. The armor plate 243 may comprise segments, or one contiguous piece circumscribing hole 203. The armor plate 243 may be made of any high strength or ballistic resistant material, such as steel, titanium, aluminum, or composites such as high strength polymer fiber composites, fiberglass, or carbon composite laminates. In one exemplary embodiment, the armor plate 243 is one contiguous rectangular component made of “S-glass” structural fiberglass sheet.
The panels of
The metal frame 110 of door posts 106 and 109 may be a high strength, light weight structural material such as aluminum, magnesium, or various composites. In one embodiment a suitable frame 110 is fabricated from high strength aircraft grade aluminum, such as 6061 T-6. The frame members may be fabricated by various methods, such as extrusion, molding, casting, and forming. Additionally, the frames may comprise any cross-sectional shape such as for example the contoured shapes depicted, or vary in cross-sectional shape. The outer shell 112 may be fabricated from any rigid and durable material such as fiberglass or metal. In one preferred embodiment, the shell 112 is fabricated from stainless steel sheet of between approximately 0.016 and 0.036 inches in thickness.
The ballistic composite blanket 111 may be a consolidated, multi-layer stack of unidirectional fiber ballistic fabric layers of the same type described above in reference to ballistic composite 42. In one exemplary embodiment the composite blanket 111 comprises 30 layers of 0/90 cross plied T-Flex® unidirectional ballistic fabric. The composite blanket 111 may be consolidated separately from or together with frame 110. In one embodiment the composite blanket 111 is molded and cured to a desired contoured shape before being combined with the door frame 110. The composite blanket 111 may also be bonded to one or both of the frame 110 and outer shell 112. Bonding may be carried out with any of the thermoplastic resins or epoxy type adhesives discussed above for example with respect to attaching skins to cores. Exemplary bonding materials include A4700 Urethane sold by Deerfield Urethane, and Scotch Weld AF-163-2 manufactured and sold by 3M.
Alternatively as shown in
It should be noted that the depicted cross-sectional shapes of the door posts are purely exemplary, and that the constructions and materials disclosed herein apply to door posts of various shapes or designs. For example, instead of the contoured shapes shown in
The ballistic composite portions of the panels and door posts of the present invention, such as ballistic portions 41, 61, 241, 242, and ballistic blanket 111, may further include reinforcement stitching. Referring to
The composite 312 is formed of multiple overlying layers of ballistic yarns comprising continuous high-strength, high-modulus fibers of the type and construction described herein. The exemplary fabric composite 312 may comprise between 10 and 35 overlying layers “L” of ballistic yarns. The individual layers “L” may be consolidated under heat and pressure, and stitched together using the high-strength thread 315, as discussed below, before or after being consolidated.
The panel/composite interface 314 resides between the rigid panel 311 and composite 312, as shown in
Continuing with
The ballistic assembly 310 may further include one or more rows of a continuous perimeter stitch 332 running along adjacent marginal edges of the composite 312. Opposing linear segments 332A, 332B of the perimeter stitch 332 may be substantially parallel to respective stitch lines 331A and 331 B, and may be spaced such that the distance “d” between adjacent parallel stitch lines is substantially equal. In one exemplary embodiment, the continuous perimeter stitch 332 comprises two rows of stitches spaced approximately one half inch apart, with the outermost stitch spaced approximately one half inch from the perimeter edge of the composite 312. The exemplary high-strength thread 315 comprises fibers having high tensile strength, elastic modulus, and strain to failure. For example, such fibers may have a tensile strength greater than about 2000 MPa and an elastic modulus greater than about 60 GPa.
The mounting plate 160 includes a perimeter portion that is relatively soft or bendable compared to the main, central portion of the plate. For example, in one embodiment the perimeter portion comprises flanges 165 extending from some or all edges of the plate 160. The flanges 165 are thinner than rest of the plate 160, and in one embodiment are less than half the thickness of plate 160. Notches 168 in the structural portion 162 receive the flanges 165, trapping the mounting plate in the panel assembly in the structural material. Installation of the mounting plate may be simplified for panels comprising two structural portions 162 like the construction depicted in
Illustrated in
For the purposes of describing and defining the present invention it is noted that the use of relative terms, such as “substantially”, “generally”, “approximately”, and the like, are utilized herein to represent an inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.
Exemplary embodiments of the present invention are described above. No element, act, or instruction used in this description should be construed as important, necessary, critical, or essential to the invention unless explicitly described as such. Although only a few of the exemplary embodiments have been described in detail herein, those skilled in the art will readily appreciate that many modifications are possible in these exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the appended claims.
In the claims, any means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. Unless the exact language “means for” (performing a particular function or step) is recited in the claims, a construction under §112, 6th paragraph is not intended. Additionally, it is not intended that the scope of patent protection afforded the present invention be defined by reading into any claim a limitation found herein that does not explicitly appear in the claim itself.
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