Patent Application
20120180627
1. Field of the Invention
The present invention relates to explosive blast attenuation devices.
2. Description of Related Art
In combat situations, such as in military, police, and/or armored transport operations, it is desirable to protect vehicles, such as tanks, personnel carriers, trucks, and the like, as well as the vehicle's contents, from damage by blasts resulting from detonated explosive devices. Accordingly, such vehicles are known to have elements, such as blast attenuators, that absorb and/or redistribute a blast impulse to reduce the likelihood that the blast will cause penetration of the vehicle. If the blast wave and/or associated spall or shrapnel penetrate the vehicle, the occupants of the vehicle may be injured or the vehicle's ability to operate may be impaired. It is similarly important to protect buildings and other such structures from the deleterious effects of explosive blasts.
One way of at least partially protecting a vehicle and the like from the destructive effects of explosive blasts is to provide armor on the exterior of the vehicle. Such armor typically is made from thick steel plate, which increases the weight of the vehicle substantially. The armor must be sufficiently strong to prevent the blast wave resulting from the explosive blast from penetrating or rupturing the armor.
Another way of protecting vehicles and the like from the destructive effects of explosive blasts is to add crushable elements to the vehicle. Typical crushable elements used in blast attenuators include, for example, honeycomb, foam, and/or corrugated panels that absorb the explosive blast wave. While such crushable elements are effective in absorbing blast loads, they are volumetrically inefficient. Crushable elements having large volumes are required to dissipate the energy of the explosive blast.
While protecting the vehicle or structure and its occupants and equipment is generally of primary importance, other factors may play a role in the design of blast attenuators for the vehicle. For example, it is not desirable for the vehicle's overall size to increase greatly as a result of adding blast attenuators or other such blast protection devices to the vehicle. It is logistically important for existing transportation equipment (e.g., trucks, trailers, aircraft, and the like) to be capable of transporting the vehicle. If the size of the vehicle is increased over previous vehicles, the existing transportation equipment may not be capable of transporting the vehicle, or the existing transportation equipment may be limited to carrying fewer vehicles per load. Additionally, it is desirable to maximize the internal volume of the vehicle to allow adequate space to house the crew and crew gear. Accordingly, blast attenuators having lower volumes generally result in vehicle designs having larger internal volumes. The overall size of the vehicle is also a factor in combat situations. Generally, smaller targets (i.e., smaller vehicles) are more difficult to hit with artillery, such as rockets, mortars, missiles, and the like. Thus, it is desirable for the vehicle's overall size to be smaller, rather than larger, to reduce the likelihood of an artillery hit or explosive impact.
There are many designs of blast attenuators that are well known in the art; however, considerable shortcomings remain.
There is a need for an improved blast attenuator.
Therefore, it is an object of the present invention to provide an improved blast attenuator and a method of making the blast attenuator.
These and other objects are achieved by providing a blast attenuator, including an enclosure defining a cavity; a core defining a plurality of interconnected pores, the core disposed in the cavity; and a shear thickening fluid disposed in the cavity, such that the shear thickening fills a portion of a pore volume of the core.
In another aspect, the present invention provides a blast attenuation assembly. The blast attenuation assembly includes a blast attenuator including a shear thickening fluid and a crushable element that omits a shear thickening fluid operably associated with the blast attenuator.
In yet another aspect of the present invention, a method is provided. The method includes the steps of providing a rigid core defining a plurality of interconnected pores and placing an enclosure about the core, the enclosure defining a filling port. The method further includes the steps of filling at least a portion of a pore volume of the core with a shear thickening fluid and closing the filling port to seal the enclosure and form a first blast attenuator.
In another aspect, the present invention provides a method including the steps of providing a blast attenuator including a shear thickening fluid, providing a crushable element that omits a shear thickening fluid, and operably associating the blast attenuator and the crushable element.
The present invention provides significant advantages, including: (1) providing lower cost means for attenuating explosive blasts than conventional thick armor or conventional crushable elements; (2) providing lighter weight means for attenuating explosive blasts than conventional thick armor; and (3) providing lower volume means for attenuating explosive blasts than conventional crushable elements.
Additional objectives, features and advantages will be apparent in the written description which follows.
The novel features believed characteristic of the invention are set forth in the appended claims. However, the invention itself, as well as, a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, in which the leftmost significant digit(s) in the reference numerals denote(s) the first figure in which the respective reference numerals appear; wherein:
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
It should be appreciated that the following terms and phrases are intended to have a particular meaning throughout the following detailed description. The term “open-celled foam,” as it relates to the present disclosure, means a cellular structure containing a large volume fraction of pores forming an interconnected network. In this disclosure, the terms “foam” and “sponge” are used interchangeably.
The present invention represents a blast attenuator for lessening the destructive effects of blasts resulting from the detonation of explosive devices, such as mines, improvised explosive devices, bombs, and the like. Generally, the blast attenuator of the present invention comprises a core comprising a plurality of interconnected pores. Preferably, the core comprises a metallic material. A shear thickening fluid fills at least a portion of the pore volume of the core. The core and the shear thickening fluid are contained within an enclosure. In some embodiments, a spall liner is disposed adjacent a back surface of the enclosure and, thus, is operably associated with the blast attenuator. Moreover, in some embodiments, a face sheet is disposed adjacent a front surface of the core and, thus, is operably associated with the blast attenuator. In use, the armor is oriented such that a blast wave resulting from a detonated explosive device or a ballistic round will preferably encounter the face sheet first, if the face sheet is provided.
Preferably, core 105 comprises an open-celled foam. More preferably, core 105 comprises an open-celled metallic foam, such as an exemplary metallic foam 201 of
Core 105 comprises a structural network defining a plurality of interconnected pores. Such a configuration is exemplified in metallic foam 201 of
A pore volume of core 105 corresponds to the individual volumes of the plurality of pores 205, in the aggregate, bounded by enclosure 103. In other words, the pore volume of core 105 corresponds to the volume of enclosure 103 less the volume of structural network 203. According to the present invention, shear thickening fluid 107 fills at least a portion of the pore volume of core 105 and is retained within the pores, such as pores 205, by enclosure 103. Preferably, shear thickening fluid 107 fills a majority of the pore volume of core 105 and, more preferably, shear thickening fluid 107 fills substantially all of the pore volume of core 105.
Generally, shear thickening or dilatant fluids are non-Newtonian fluids that exhibit increasing viscosities with increasing shear rates. For example, a shear thickening fluid, when manipulated at a low shear rate, exhibits low viscosity and acts as a liquid. When manipulated at a high shear rate, however, the shear thickening fluid exhibits high viscosity and acts more like a solid. Shear thickening fluids exhibit no yield stress.
It is believed that, at rest, few voids exist in the shear thickening fluid and the liquid present is sufficient to fill the void space. At low shear rates, the liquid lubricates the motion of each particle past others and the resulting stresses are consequently small. At high shear rates, however, the shear thickening fluid expands or dilates slightly, so that there is no longer sufficient liquid to fill the increased void space and prevent direct solid-solid contacts, which results in increased friction and higher shear stresses. It is believed that this mechanism causes the apparent viscosity to rise rapidly with increasing rate of shear. Examples of shear thickening fluids (e.g., shear thickening fluid 107) include, but are not limited to, dispersions of cornstarch in water, dispersions of silica in ethylene glycol, dispersions of clays in water, dispersions of titanium dioxide in water, and dispersions of silica in water.
Preferably, in at least one embodiment, shear thickening fluid 107 comprises silica particles dispersed in ethylene glycol. More preferably, the silica particles exhibit diameters of at least 200 nanometers. Moreover, it is preferable for shear thickening fluid 107 to exhibit a volume fraction of silica particles of at least about 0.4. The composition of shear thickening fluid 107 employed in blast attenuator 101 is implementation specific, depending at least upon the velocity, intensity, etc. of the explosive blast wave that blast attenuator 101 is expected to encounter. It should be noted that blast attenuator 101 may comprise any suitable shear thickening fluid 107.
Still referring to
In various embodiments, for example, face sheet 109 comprises titanium; titanium alloyed with one or more other elements; aluminum; aluminum alloyed with one or more other elements; an organic-matrix composite material, such as, for example, graphite-, carbon-, or fiberglass-reinforced epoxy composite material; a metal-matrix composite material, such as carbon-, silicon carbide-, or boron-reinforced titanium or aluminum composite material; a laminated material, such as titanium/aluminum laminate; or the like. Preferably, face sheet 109 comprises titanium; titanium alloyed with one or more other elements; aluminum; aluminum alloyed with one or more other elements; an organic-matrix composite material, such as, for example, graphite-, carbon-, or fiberglass-reinforced epoxy composite material; a laminated material, such as titanium/aluminum laminate; or the like.
Preferably, spall liner 111, if present, comprises a material that will drastically reduce the velocity of spall (e.g., shrapnel and the like) exiting blast attenuator 101. Accordingly, spall liner 111 may be disposed adjacent any surface of enclosure 103 from which spall is expected to exit. More preferably, spall liner 111 comprises a material that will substantially prevent the spall from exiting blast attenuator 101. For example, in various embodiments, spall liner 111 comprises one of the materials disclosed above of which face sheet 109 is comprised. Preferably, spall liner 111 comprises titanium; titanium alloyed with one or more other elements; aluminum; aluminum alloyed with one or more other elements; an organic-matrix composite material, such as, for example, graphite-, carbon-, or fiberglass-reinforced epoxy composite material; polyethylene; a laminated material, such as titanium/aluminum laminate; or the like. It should be noted, however, that the particular compositions of face sheet 109 and spall liner 111 are implementation specific. Accordingly, the present invention contemplates faces sheets (e.g., face sheet 109) and spall liners (e.g. spall liner 111) comprising any material suitable for a particular implementation.
A blast attenuator (e.g., blast attenuator 101 or 803) or a blast attenuation assembly (e.g., blast attenuation assembly 501, 601, or 801) of the present invention may be operably associated with a vehicle, building, or other such structure to inhibit the deleterious effects of an explosive blast on the vehicle, building, or other such structure. Accordingly,
It should also be noted that any of the embodiments of the blast attenuator or blast attenuation assembly disclosed herein, and their equivalents, may be operably associated with any structure. In this sense, the term “structure” means any interconnected collection of parts forming a device, apparatus, or the like, and includes, but is not limited to, a vehicle and a building.
The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below. It is apparent that an invention with significant advantages has been described and illustrated. Although the present invention is shown in a limited number of forms, it is not limited to just these forms, but is amenable to various changes and modifications without departing from the spirit thereof.
