Lightweight penetration resistant door post

Designs and methods are provided for a lightweight, penetration resistant door post. In one embodiment the door post comprises an elongated structural frame, and a ballistic composite blanket overlaying the elongated structural frame. The ballistic composite blanket may comprise multiple stacked arrays of unidirectional ballistic fiber bundles. The exemplary door post may further comprise an outer shell overlaying the ballistic composite blanket.

TECHNICAL FIELD AND BACKGROUND

The present invention generally relates to anti-ballistic and penetration resistant structures, such as panels, bulkheads, and doors.

DESCRIPTION OF THE EMBODIMENTS

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.

Depicted inFIG. 1is a schematic cross-section view of an exemplary lightweight armored panel30. The panel30may be adapted for use in walls, doors, dividers, bulkheads, or any structural member requiring ballistic resistance and structural integrity. In one particular embodiment, panel30is an aircraft panel designed to meet the FAA mandated requirements applied to aircraft interior doors and bulkheads for resistance to forcible intrusion by unauthorized persons and resistance to penetration by small arms fire and fragmentation devices.

The armored panel30in overview comprises a structural portion31made of a structural core32enclosed by rigid inner and outer core skins33and34. Panel30further comprises a ballistic portion41consisting of a ballistic composite element42enclosed by inner and outer ballistic skins43and44. The structural portion31is adhered to the ballistic portion41using a compatible resin or adhesive. In one embodiment of panel30the structural portion accounts for more than half the total thickness of the panel. For example, an exemplary panel30may comprise a structural portion31approximately 0.75 inches thick combined with a ballistic portion41approximately 0.35 inches thick.

The structural core32serves in part as a structural element of the structural portion31, stabilizing the core skins33,34, 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 core32may 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 core32may 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 core32comprises 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 core32is 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 skins33,34are 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 core32. 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 skins33or34as 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 panel30. 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 skins33,34may be bonded to the structural core32using 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 portion31, ballistic portion41of armored panel30may be a sandwich structure comprising a ballistic core42between inner and outer ballistic skins43,44. For example, ballistic core42may 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 core42, 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 composite42is at least 80% of the total weight of the ballistic composite.

In one particular embodiment of a process for creating a ballistic composite42, 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 composite42. 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 composite42comprises 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 skins43,44add strength to the ballistic composite42as well as participate in arresting the progress of a projectile striking the panel30. Outer ballistic skin44in 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 skins43,44may comprise a rigid composite material such as fiberglass or any of the composite structural materials previously discussed in reference to the core skins33,34. For example the ballistic skins43,44may be pre-preg fiberglass sheets that are adhered to the ballistic composite42during 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 skins43,44are 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 panel30is assembled by bonding the structural portion31to the ballistic portion41using 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.

FIG. 2shows an alternative construction to that ofFIG. 1in which the structural portion of an armored panel60is comprised of two structural portions61. Each structural portion61is constructed of a structural core62sandwiched between core skins63and64. Depending upon the particular application, the materials, dimensions, and adhesives used in construction of structural portion61may, or may not be the same as those used for structural portion31. In one exemplary embodiment the structural cores62are both the Plascore PAMG-XR1-8.1-1/8-5056 aluminum honeycomb, each approximately 0.37 in. thick; and the core skins63,64are each the J D Lincoln Fiberply L-201 cross plied prepreg fiberglass. The component elements of structural portions61may each be assembled into unitized panels as previously described with reference to structural portion31of panel30. The structures61along with ballistic portion41may be bonded together using suitable adhesive layers51such as for example the previously noted 3M VHB F9473PC adhesive transfer tape. Alternatively, all of the layers comprising the ballistic portion41and structural portions61may 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.FIGS. 3 and 4depict a ballistic panel201containing a hatch202, wherein the ballistic panel201comprises a structural portion231and ballistic portion241; and hatch202comprises a structural portion232and ballistic portion242. A seam210is defined between the edge of a hole203in the panel201and the edge of the hatch202. The ballistic portion242of hatch202extends beyond the edge of the structural portion232, creating a perimeter flange245. The perimeter flange245and ballistic portion242may comprise for example a ballistic fiber composite layer and a fiberglass outer skin. As shown inFIG. 4, the ballistic portion241of panel201is recessed from the edge of hole203, creating a notch for receiving perimeter flange245. The perimeter flange245thus overlaps the seam210and the notched portion of the edge of panel201on the side from which a potential attack would be expected to come, referred to herein as the “threat side”.

A threat side seam251is defined between the outer edge of perimeter flange245and the recessed edge of ballistic portion241of panel201. In one embodiment an armor plate243is embedded in the structural portion231of panel201beneath seam251. The armor plate243is overlapped by both the ballistic portion241of the panel201, and the perimeter flange245extending from the edge of hatch202. The armor plate243may comprise segments, or one contiguous piece circumscribing hole203. The armor plate243may 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 plate243is one contiguous rectangular component made of “S-glass” structural fiberglass sheet.

FIG. 5depicts another two-panel assembly260, in which a first panel261includes a perimeter flange265that overlaps a portion of an adjacent coplanar second panel271. The panels may be of the same construction described above in reference to panel201and hatch202. In particular, perimeter flange265may comprise a ballistic fiber composite layer on the threat side of the first panel that covers a seam270between the first and second panels.

The panels ofFIG. 5may further comprise outer skins272and273on the protected side of the first and second panels respectively. The outer skin273extends beyond the edge of second panel271, creating a perimeter flange275similar to perimeter flange265on the threat side of the first panel261. The perimeter flange275overlaps a portion of the protected side (the side opposite the threat side) of the first panel. Skin272of first panel261may be recessed away from the edge as shown to create a notch for receiving flange275. The flange275may be comprised of any rigid material, such as fiberglass or sheet metal, with enough stiffness to deflect material particles that may be ejected through seam270from a ballistic impact on or near perimeter flange265. In one embodiment the outer skin273and flange275of the second panel271comprise the outer skin of the panel. In another embodiment, outer skin273and flange275comprise a separate layer that overlies an outer skin of second panel271and first panel261.

FIG. 6illustrates an exemplary bullet proof door assembly101comprising a ballistic door104mounted via hinges105to a hinge-side ballistic frame member106, and a latch-side ballistic frame member109. Door posts106and109may comprise a frame110, a ballistic composite blanket111, and an outer shell112. In one preferred embodiment the door posts are oriented such that the outer shell112is on the threat side. Accordingly the door may be configured as shown, with the door104positioned to abut the door posts from the protected side, and door posts configured with the outer shell112facing the threat side.

The metal frame110of door posts106and109may be a high strength, light weight structural material such as aluminum, magnesium, or various composites. In one embodiment a suitable frame110is 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 shell112may be fabricated from any rigid and durable material such as fiberglass or metal. In one preferred embodiment, the shell112is fabricated from stainless steel sheet of between approximately 0.016 and 0.036 inches in thickness.

The ballistic composite blanket111may be a consolidated, multi-layer stack of unidirectional fiber ballistic fabric layers of the same type described above in reference to ballistic composite42. In one exemplary embodiment the composite blanket111comprises 30 layers of 0/90 cross plied T-Flex® unidirectional ballistic fabric. The composite blanket111may be consolidated separately from or together with frame110. In one embodiment the composite blanket111is molded and cured to a desired contoured shape before being combined with the door frame110. The composite blanket111may also be bonded to one or both of the frame110and outer shell112. 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.

FIGS. 7 through 9illustrate various embodiments of the door posts in which a gap is provided between the ballistic blanket111and the frame110in certain areas. The inventors have discovered that the ability of the door posts to stop a ballistic projectile is substantially reduced in areas of a cross-section that are not straight, such as the corner areas. InFIG. 7form example, a door post120comprises an inside corner121(when viewed from the threat side) where the ballistic blanket111has been spaced away from the door frame110by a relatively thin and flexible spacer strip122. The spacer strip may be any flexible material such as for example thin sheet metal. The effect of the spacer strip122is to replace the relatively sharp inside corner with a large, flat 45 degree surface that flexibly supports the ballistic blanket, and provides a space between the ballistic blanket and the relatively rigid door frame corner into which the ballistic blanket and spacer strip can deflect.

Alternatively as shown inFIGS. 8 and 9, a rigid but crushable material such as structural foam is used to support the ballistic blanket in a spaced relationship to critical areas of the underlying door frame. In the embodiment ofFIG. 8for example, a door post130incorporates a foam spacer131on outside corners between the ballistic blanket material and the door frame. Beveled outside door frame corners132provide for additional spacing and foam volume. Another foam spacer is used to treat the inside corner133in much the same way as the flexible spacer strip122of theFIG. 7embodiment. In the embodiment ofFIG. 9, a foam block141is used to completely fill an inside corner of the door post140, eliminating the inside corner from the ballistic blanket. The foam spacers may be molded in place, or pre-formed to the desired dimensions and then bonded to the door frame. In one exemplary embodiment the foam material is pre-formed, and made of a rigid structural foam sold by Evonik Industries of Germany under the trade name Rohacell® IG/IG-F. Alternatively, spacing between the ballistic blanket and the door frame may be achieved without use of any type of spacer strip or foam by simply molding the ballistic blanket to a shape that creates the desired spacing.

FIG. 10illustrates another embodiment of the invention in which the concept of using a spacer material to separate the ballistic blanket from the underlying door frame has been extended to the entire surface of the door frame. In particular, overlying the threat side of a door frame150is a crushable spacer layer151, a ballistic blanket111, and an outer shell112. The crushable spacer layer151may be any rigid, crushable material such as the crushable foams discussed in reference toFIGS. 8 and 9, or the honeycomb materials previously described with respect to the door panels. The spacer layer151may be bonded to the door frame and ballistic blanket with a suitable adhesive, such as any of the previously described resins, epoxies, or transfer tapes.

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 inFIG. 4, a door post could be simply a flat plate, a channel that fits around the edge of a panel, or any other shape. The arrangement and orientation of the elements of the door posts are also not intended to be exclusive. For example, the ballistic composite blanket111could be on the protected side of the door frame110, such that a ballistic projectile from the threat side would encounter the ballistic composite blanket111after penetrating the door frame110. Various other foreseeable arrangements not specifically mentioned are likewise not intended to be excluded the scope of the present invention.

The ballistic composite portions of the panels and door posts of the present invention, such as ballistic portions41,61,241,242, and ballistic blanket111, may further include reinforcement stitching. Referring toFIGS. 11 and 12, an exemplary ballistic assembly310comprises a flexible ballistic fiber composite312, a rigid panel311, a panel/composite interface314, and high-strength sewing thread315. The exemplary panel311includes an outside major surface311A, and an opposing inside major surface311B. The rigid panel311may correspond for example to one or both of the ballistic skins43,44facing the ballistic composite42ofFIG. 1, or a separate dedicated rigid layer facing a flexible ballistic fiber composite, alone or in combination with external skins such as skins43,44.

The composite312is 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 composite312may 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 thread315, as discussed below, before or after being consolidated.

The panel/composite interface314resides between the rigid panel311and composite312, as shown inFIG. 12, and may comprise an adhesive321and cross-plied ballistic fabric322. The panel/composite interface314forms an expansive bonding joint (or “bonding zone”) which cooperates with the high-strength thread315to mitigate damage to, and delamination of the composite312from ballistic impact. The bonding joint may cover substantially the entire inside major surface311B of the rigid panel311. The adhesive321may be a thermoplastic urethane film or other suitable polymer film, resin, or bonding agent previously discussed.

Continuing withFIGS. 11 and 12, a high-strength thread315is passed (e.g., sewn) through all layers “L” of a composite laminate312and extends around the unidirectional panel-side yarns325of the panel/composite interface314along continuous linear stitch lines331A,331B running substantially perpendicular to the yarn orientation. Two or more ends of high-strength thread315may be used in a lockstitch sewing technique commonly known in the industry. The stitched thread315cooperates with the panel-side ballistic yarns325to promote increased joint resistance against tensile loadings and ballistic impacts, in-plane shear, and anti-plane shear. As best shown inFIG. 11, the exemplary ballistic assembly310may include multiple, equally spaced, parallel lines331A,331B of stitching which run substantially continuously from one edge of the flexible backing312to the opposite edge. In one embodiment the stitch lines331A,331B are spaced apart approximately 2-6 inches, and comprise approximately 4 stitches per linear inch. The high-strength thread315may provide structural reinforcement and enhanced energy absorption along a z-axis of the ballistic assembly310.

The ballistic assembly310may further include one or more rows of a continuous perimeter stitch332running along adjacent marginal edges of the composite312. Opposing linear segments332A,332B of the perimeter stitch332may be substantially parallel to respective stitch lines331A and331B, and may be spaced such that the distance “d” between adjacent parallel stitch lines is substantially equal. In one exemplary embodiment, the continuous perimeter stitch332comprises 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 composite312. The exemplary high-strength thread315comprises 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.

FIGS. 13 and 14illustrate a ballistic resistant mounting plate for attaching hardware and load carrying items such as latches, deadbolts, hinges, seats, and the like to a lightweight ballistic panel assembly. A metal mounting plate160is recessed within a ballistic panel assembly161, comprising structural portion162, and a ballistic portion163. The structural and ballistic portions162,163may comprise the previously described core and skin constructions of portions31and41of panel30for example. An outer surface166of mounting plate160is substantially flush with the back surface164of the panel assembly161, and an inner surface167of plate160is recessed within the structural portion162. The outer surface provides a hardware mounting surface, and may incorporate for example threaded holes suitable for hardware attachment.

The mounting plate160includes 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 flanges165extending from some or all edges of the plate160. The flanges165are thinner than rest of the plate160, and in one embodiment are less than half the thickness of plate160. Notches168in the structural portion162receive the flanges165, 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 portions162like the construction depicted inFIG. 2. In that case, rather than creating a notch to receive flange165, the mounting plate may be simply recessed into the inner facing surface of the structural portion containing the mounting plate prior to bonding the two structural portions together.

Illustrated inFIG. 15is an alternative hardware mounting plate170comprising an outer surface176, inner surface177, and a relatively flexible perimeter flange175on two or more sides of plate170. Mounting plate170further comprises a broad recess178in the central portion of the outer surface176. The recess178may cover most of the area of the outer surface176as shown. The recess178in mounting plate170may be utilized to create a gap between the mounting plate and any hardware component or mechanism attached to the plate, where the size of the gap is defined by the depth of the recess. The gap allows for plate170to deflect to a certain extent toward a component attached to outer surface176before coming into physical contact with the component.

FIGS. 16 and 17illustrate a threaded insert design that utilizes a relatively large perimeter flange. Threaded inserts may be utilized for attaching various hardware components to lightweight ballistic panels, such as for example hinges and latches.FIG. 16depicts one embodiment of a threaded insert181having a flange portion182extending laterally from the base of the insert. The width or diameter of flange portion182may be approximately two to four times the diameter of the body portion of the insert. In one version the flange portion182is also relatively thin and flexible compared to the body portion of the insert181. Insert181is mounted in a ballistic panel185comprising a ballistic portion184, and a structural portions183, with the insert oriented to protrude on the side of panel185opposite the ballistic portion184. The flange182is countersunk flush with the surface of structural portion183facing the ballistic portion184, trapping the flange between the ballistic portion and the structural portion.

FIG. 17depicts a shorter flanged insert191with an oversized flange192. In this embodiment the insert191is mounted in a ballistic panel195that includes two structural portions,193and196, instead of the single structural portion of theFIG. 16embodiment. The insert191is again oriented such that the threaded end protrudes on the structural side of the panel. In this embodiment the flange192is recessed in the surface of structural portion196that faces structural portion193, trapping the flange between the structural portions in the middle of panel195instead of between the ballistic portion and structural portion as in theFIG. 16embodiment.

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.