Patent Application
20090090236
The present invention is directed to a modular blast-resistant panel system. More specifically, the present invention provides a composite panel system for retrofitting existing structural elements for improved resistance to applied forces.
Due to the worldwide increase in terrorist incidents, and the use of explosive devices in such incidents, there has been increased interest in building structures that are capable of withstanding very large applied forces (such as explosive blasts). Similarly, efforts have been made to retrofit existing structures with blast-resistant surfaces.
For example, some blast-resistant polymer coatings have been developed to “spray on” to existing masonry walls (such as concrete block and/or brick structures) in order to prevent the shattering of such structures in response to an explosive force. Such conventional blast-resistant coatings have proven effective for preventing the generation of potentially deadly debris by reducing the likelihood that such masonry structures shatter and/or decompose in response to the application of a blast force. While such conventional blast-resistant coatings are relatively easy to apply (via liquid spray, for example), they may fail to provide adequate blast resistance to preserve an existing structure during an excessive blast force (such as that accompanying the detonation of a relatively large explosive device).
Furthermore, such conventional blast-resistant coatings may not be effective for retrofitting some existing steel and/or cast iron structures for increased blast-resistance. For example, many existing structures, such as traffic structure systems and/or subterranean train structures are supported by relatively old cast iron structures having rusted, irregular surfaces and/or structural ribbing that may prevent an even coating of conventional “spray on” blast-resistant coatings. Furthermore, conventional blast-resistant polymer coatings may do little to further reinforce cast iron and/or poured concrete structures that may be subjected to very large blast forces originating inside the structure (for example, blast forces approaching and/or exceeding 50 kilopounds per square inch (ksi) that may be the result of large and/or powerful bombs that may be carried in luggage, in a vehicle, and/or pre-placed on an access pathway defined in a train structure).
In addition, it is well known that blast forces may be absorbed and/or mitigated using pumice powder and/or pebbles. For example, various military forces pack live ammunition in pumice. Because the pumice is air-filled and easily pulverized, it acts to absorb the explosive blast and/or shock should a single round of ammunition be ignited. This blast and/or shock absorption quality may prevent the chain-reaction explosion of some or all of the remaining rounds packed with the ignited round. While pumice has been shown to be an excellent blast and/or shock absorbing material, it is not easily integrated into a modular reinforcement structure, as it is most effective as a pulverizable pebble. Furthermore, pumice (or perlite materials, which have similar pulverizable characteristics) on its own, cannot prevent the penetration of shrapnel or other projectiles that may accompany the explosion of a bomb.
Thus, there exists a need in the art for a modular panel and/or reinforcing structure that is capable of absorbing and/or redirecting large blast forces (at or near 50 ksi, for example) that may be exerted on existing structures or structural components. There further exists a need in the art for such a modular panel and/or reinforcing structure that combines excellent shock absorption characteristics with other characteristics (such as, for example anti-ballistic capabilities, shrapnel protection, and/or blast-deflection capabilities) that may better protect a potentially vulnerable structure.
The embodiments of the present invention satisfy the needs listed above and provide other advantages as described below. Embodiments of the present invention may include a blast-resistant assembly adapted to be operably engaged with an existing structural element to protect the existing structural element from an applied force (such as an explosive force and/or shock resulting from a detonated explosive device). In one embodiment, the assembly comprises a first ballistic-resistant composite panel, and a second ballistic-resistant composite panel disposed substantially parallel to and spaced apart from the first ballistic-resistant composite panel. The assembly further comprises an energy absorbing core operably engaged between the first ballistic-resistant composite panel and the second ballistic-resistant composite panel. In some embodiments, the energy absorbing core comprises a composite material configured to absorb at least a portion of the applied force by pulverizing in response to the applied force. For example, the energy absorbing core may comprise a particulate pulverizable material suspended in a matrix material. According to some such embodiments, the pulverizable material may include, but is not limited to: pumice; perlite; urethane foam; PVC foam; aluminum foam; aluminum honeycomb; balsa; and combinations of such materials.
The modular assembly embodiments of the present invention may be contoured and/or shaped to fit the contours of an existing structural element. For example, in some embodiments, the ballistic-resistant composite panels and the energy absorbing composite core may be substantially flat so as to be adapted to be operably engaged with an existing structural element having a substantially flat surface (such as a substantially flat vertical wall and/or a substantially flat angled or horizontal roof surface). In other embodiments, the ballistic-resistant composite panels and the energy absorbing core may be curved so as to be adapted to be operably engaged with an existing structural element having a curved surface (such as, for example, the interior of a structure having a circular cross-section, and/or a roof of a domed and/or semi-cylindrical structure).
According to various assembly embodiments of the present invention, the first and second ballistic-resistant composite panels may comprise a variety of composite materials configured to stop and/or decelerate shrapnel or other projectiles and to prevent the incursion of such materials into the energy absorbing core. For example, the first and second ballistic-resistant composite panels may comprise materials including, but not limited to: fiber reinforced polymer materials; fiber reinforced polymer composites; solid laminates; and combinations of such ballistic-resistant materials. For example, in some embodiments, the ballistic-resistant composite panels may comprise a fiber component disposed substantially within a resin component wherein the fiber component may include, but is not limited to: s-glass; aramid fiber; carbon; polyethylene; polybenzoxazole (PBO); nylon; steel wire; polyester cord; and combinations of such fibers. Furthermore, according to such embodiments, the resin component may include, but is not limited to: vinyl ester resin; epoxy; phenolics; and combinations of such resin components.
In order to deflect at least some of the applied force laterally and/or otherwise away from the existing structural element, some assembly embodiments of the present invention further comprise an energy deflecting panel operably engaged with at least one of the first and second ballistic-resistant composite panels. In some embodiments, the energy deflecting panel may comprise a sacrificial material configured to crack in response to the applied force so as to deflect the applied force away from the existing structural element. According to some such embodiments, the sacrificial material of the facing may include, but is not limited to: granite; quartz composite; steel; aluminum; manganese; ceramic; fiber reinforced polymer material comprising a fiber component disposed substantially within a resin component; and combinations of such materials. In other embodiments, the energy deflecting panel may comprise a plurality of substantially rigid particles at least partially suspended in a substantially elastic matrix such that the applied force is at least partially deflected by a movement of the plurality of substantially rigid particles within the substantially elastic matrix in response to the applied force. According to some such embodiments, the plurality of substantially rigid particles may comprise a ceramic armor material and the substantially elastic matrix may comprise a high-tensile strength polymer material.
In order to provide further energy absorption characteristics, some assembly embodiments of the present invention may comprise additional energy-absorbing layers. For example, some assembly embodiments may further comprise a foam panel disposed between the energy deflecting panel and the second ballistic resistant panel. In some embodiments, the foam panel may comprise a syntactic foam material. In some additional embodiments, the assembly may further comprise a substantially compliant material disposed on at least one side of the energy deflecting panel for absorbing at least a portion of the applied force. In such embodiments, the substantially compliant material may include, but is not limited to: rubber; polyurea coating; and combinations of such energy absorbing materials.
Furthermore, various embodiments of the present invention may comprise an aperture defined in the assembly (and/or in an energy deflecting panel, ballistic-resistant composite panel, and/or energy absorbing core thereof) for receiving a connector for operably engaging the assembly with a surface of the existing structural assembly. In some embodiments, the assembly further comprises a bracket disposed between the existing structural assembly and at least one of the first ballistic-resistant composite panel and the second ballistic-resistant composite panel for operably engaging the assembly with a surface of the existing structural assembly. Such brackets may be used, for example, when the surface of the existing structural assembly (such as a structural rib) is substantially perpendicular to the assembly.
Various embodiments may further comprise one or more adhesive layers for adhering the various layers and/or components of the assembly together to form a substantially modular reinforcing assembly. For example, some embodiments comprise an adhesive layer disposed between at least one of the ballistic-resistant composite panels and the energy absorbing composite core for adhering at least one of the ballistic-resistant composite panels to the energy absorbing composite core to form a modular blast-resistant assembly. In addition, some embodiments may further comprise an adhesive layer disposed between at least one of the ballistic-resistant composite panels and the energy deflecting panel for adhering at least one of the ballistic-resistant composite panels to the energy deflecting panel to form a modular blast-resistant assembly having an energy deflecting panel. According to some such embodiments, the adhesive layer may comprise adhesive compounds that may include, but are not limited to: polyurethane adhesives; methacrylate adhesives; and combinations of such adhesives.
Some embodiments of the present invention further provide a blast-resistant reinforcement system adapted to be operably engaged with a particular type of existing structure (such as, for example, an interior surface of a structure) to protect the structure from an applied force (such as an explosion) originating from a location inside the structure. Such reinforcement system embodiments comprise a plurality of energy absorbing panels adapted to be operably engaged with the interior surface of the structure. As described herein, one or more of the plurality of energy absorbing panels may comprise an energy absorbing core comprising a composite material configured to absorb at least a portion of the applied force by pulverizing in response to the applied force. Such reinforcement system embodiments further comprise a plurality of energy deflecting panels configured to be operably engaged with the plurality of energy absorbing panels. The energy deflecting panels may, in turn, be disposed between the plurality of the energy absorbing panels and the location of the applied force so as to deflect at least a portion of the applied force away from the energy absorbing panels and the existing structure behind the energy absorbing panels.
In some such reinforcement system embodiments, the system may be configured to be capable of being operably engaged with a structure having a substantially circular cross-section such that the interior surface thereof is curved. According to such embodiments, the energy absorbing panels may be disposed substantially adjacent to one another about the interior surface of the structure such that as the energy absorbing composite core pulverizes in response to the applied force, each of the energy absorbing panels are urged further into contact with one another about the curved interior surface of the structure. Thus, according to such embodiments, the energy absorbing panels may be “locked” into contact in response to a blast that originates inside the structure.
Furthermore, according to some reinforcement system embodiments, the energy deflecting panels may be arranged relative to the energy absorbing panels so that none of the seams of these two component layers are co-located. For example, the energy deflecting panels may be operably engaged with the energy absorbing panels such that a first seam defined between each of the plurality of energy absorbing panels is not co-located with a second seam defined between each of the plurality of energy deflecting panels about the interior surface of the structure.
Furthermore, and as described above, each modular energy absorbing panel of the reinforcement system may further comprise several composite layers to improve the blast resistance and the ballistic resistance of each energy absorbing panel forming the reinforcement system. For example, in some embodiments, each of the plurality of energy absorbing panels may comprise: a first ballistic-resistant composite panel; a second ballistic-resistant composite panel disposed substantially parallel to and spaced apart from the first ballistic-resistant composite panel; and the energy absorbing core operably engaged between the first ballistic-resistant composite panel and the second ballistic-resistant composite panel.
Thus the various embodiments of the present invention provide many advantages that may include, but are not limited to: providing a modular blast-resistant assembly that may be easily attached to a variety of existing structural elements as bolt-on elements; providing a blast-resistant assembly that packages the shock-absorption capability of a pulverizable material in a robust and modular structural format; providing a blast-resistant assembly that includes a blast-deflection capability and a shock-absorption capability; and providing a complete reinforcement system for an existing interior surface of a structure including a plurality of interconnected modular blast-resistant panels. These advantages, and others that will be evident to those skilled in the art, are provided in the various embodiments of the present invention.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may 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 satisfy applicable legal requirements. Like numbers refer to like elements throughout. The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.
Although some embodiments of the invention described herein are described in terms of a blast-resistant reinforcement system adapted to be operably engaged with an interior structure of a tunnel system, it will be appreciated by one skilled in the art that the invention is not so limited. For example, as shown generally in
Referring to
The energy absorbing core 12 may comprise a pulverizable material 13 suspended in a matrix material or other binder component. The pulverizable material 13 may be configured to absorb the energy transmitted by the applied force (such as a shock wave and/or blast force generated by an explosion) by pulverizing into smaller components in response to the applied force. For example, the energy of a shock wave and/or blast force may be dissipated in breaking down the pulverizable material 13 into smaller components such that only some portion of the initial applied force is actually transmitted to the existing structural element 100. Furthermore, in some embodiments, the pulverizable material 13 may be provided in particles of various sizes (including some relatively large size particles) such that some secondary applied forces (such as secondary blasts and/or additional explosive blasts) may be further absorbed in a second pulverizing cycle before the pulverizable material 13 is fully broken down into a fine powder (which may be less capable of absorbing and/or dissipating the applied force). In some embodiments, the energy absorbing core 12 may comprise pulverizable material 13 (in particulate form or other forms) that may include, but is not limited to: pumice; perlite; urethane foam; PVC foam; aluminum foam; aluminum honeycomb; balsa; and combinations of such pulverizable materials. The matrix in which the pulverizable material 13 may be suspended may include, but is not limited to: an epoxy matrix, a semiliquid matrix; a polymer matrix; an adhesive matrix; and combinations of such matrix materials.
For example, in one embodiment, the pulverizable material 13 may comprise a plurality of individual particles of pulverizable material 13 (such as pumice “pebbles” for example) of a selected size distribution suspended in a matrix comprising a matrix material (such as an epoxy, for example). According to such embodiments, the size distribution of the particles of pulverizable material 13 may range from ¼ (one quarter) inch to 1 (one) inch. In one embodiment, the pulverizable material 13 may comprise particles having a preferred size of about ⅜ (three eighths) inches. As described herein, the size distribution of the particles of pulverizable material 13 may also be substantially bi-modal by volume such that the energy absorbing core 12 may be capable of absorbing at least one primary applied force and one or more secondary applied forces (such as those resulting from secondary blasts, for example) by further pulverizing the largest particles of pulverizable material 13 remaining after the application of a first force.
The pulverizable material 13 of the energy absorbing core 12 may be effective for absorbing the energy transmitted by an applied force (such as a shock wave and/or blast force) but that the pulverizable material 13 may do little to impede the advance of particles, shrapnel, and/or debris that may accompany the application of a blast force. Such fast-moving materials may be hazardous to the integrity of the existing structural element 100 if allowed to impact some portions of the existing structural element 100. Thus, as described herein with reference to
In particular embodiments, the energy absorbing core 12 may comprise a foam material, especially syntactic foams. In a preferred embodiment, the energy absorbing core 12 comprises a NSL-8 flexible epoxy syntactic foam available commercially from Thermal Coating Technologies, Inc. of Opelousas, La.
In order to ensure that the energy absorbing panels 27 (and the resulting blast-resistant assembly 1) are relatively lightweight and robust, the ballistic-resistant composite panels 10a, 10b may comprise specialty composite materials that may include, but are not limited to: a fiber reinforced polymer material; a fiber reinforced polymer composite; a solid laminate; and combinations of such materials.
For example, the ballistic-resistant composite panels 10a, 10b may comprise fiber reinforced polymer material including a fiber component disposed substantially within a resin component, wherein the fiber component may include, but is not limited to: s-glass; aramid fiber (such as KEVLAR®, for example); carbon; polyethylene; polybenzoxazole; nylon; steel wire; polyester cord; and combinations of such fiber components. Furthermore, in some such embodiments, the resin component may include, but is not limited to: vinyl ester resin; epoxy; phenolics; and combinations of such resin components. The ballistic-resistant composite panels 10a, 10b may also comprise pre-fabricated ballistic-resistant composite panels such as, for example, ballistic-resistant fiberglass laminate panels available from Martin Marietta Composites of Raleigh, N.C.
Furthermore, in some assembly 1 embodiments, one or more of the ballistic-resistant composite panels 10a, 10b may also comprise a fiber reinforced polymer composite such as a vacuum-infused sandwich panel comprising an upper skin and a lower skin and a core material disposed substantially between the upper and lower skins. Exemplary core materials of the first composite material may include, but are not limited to: wood, foam, and various types of honeycomb. Other core materials may also include, but are not limited to: web materials embedded in a thermosetting resin and fiber-reinforced polymer resin materials. The upper and lower skins may also comprise composite materials such as polymer resin materials including fiber reinforcing elements embedded therein. Exemplary polymer resin materials may include, but are not limited to: thermosetting resins, such as unsaturated polyesters, vinyl esters, polyurethanes, epoxies, phenolics, and mixtures thereof. The fiber reinforcing elements may include, but are not limited to: E-glass fibers, S-glass, carbon fibers, KEVLAR®, metal (e.g., metal nano-fibers), high modulus organic fibers (e.g., aromatic polyamides, polybenzamidazoles (PBOs), and aromatic polyimides), and other organic fibers (e.g., polyethylene and nylon). Blends and hybrids of such materials may also be used as a reinforcing element. Other suitable composite materials that may be used as a reinforcing element within components of the first composite material may include, but are not limited to: whiskers and fibers constructed of boron, aluminum silicate, or basalt. Exemplary fiber reinforced panels that may be used as a composite floor member and methods of making such panels are disclosed in the following U.S. patents: U.S. Pat. Nos. 5,794,402; 6,023,806; 6,044,607; 6,108,998; 6,645,333; and 6,676,785, all of which are incorporated herein in their entirety. In addition, according to some embodiments of the assembly 1 of the present invention, one or more of the ballistic-resistant composite panels 10a, 10b may also comprise a TRANSONITE® composite panel (also available from Martin Marietta Composites of Raleigh, N.C.). According to some embodiments, the core of a sandwich panel used to form one or more of the ballistic-resistant composite panels 10a, 10b may be formed of a foam material with a plurality of fibers extending through the foam and connecting the two laminated skins secured to each opposing surface of the foam core. Furthermore, in some embodiments, the energy absorbing panel 27 (see
As shown generally in
Furthermore, as shown generally in
Referring again to
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While bolts or other connectors 25 may be used to facilitate the engagement of one or more components of the modular blast-resistant assembly 1 with one or more elements of an existing structure 100, the assembly 1 may also comprise one or more adhesive layers 40 for operably engaging the components of the modular blast-resistant assembly 1 with one another and/or with the existing structure 100. For example, as shown in
Furthermore, and also as shown in
As shown, for example, in
As described herein, the shape of the assembly 1 and the various components 27, 14 thereof may be tailored for application to various existing structures. For example, in some embodiments, as shown in
As shown generally in
Furthermore, as shown generally in
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According to some embodiments, the reinforcement system 400 shown in
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
