WO2014025840A2

WO2014025840A2 - Core structured components, containers, and methods of casting

Info

Publication number: WO2014025840A2
Application number: PCT/US2013/053877
Authority: WO
Inventors: Adam R. LOUKUS; Josh E. LOUKUS; Roy H. LOUKUS; Travis PENNALA; Luke LUSKIN
Original assignee: Loukus Adam R; Loukus Josh E; Loukus Roy H; Pennala Travis; Luskin Luke
Priority date: 2012-08-06
Filing date: 2013-08-06
Publication date: 2014-02-13
Also published as: WO2014025840A3

Abstract

. A container having one or more compartments therewithin, wherein an internal support structure extends through the compartments. The internal support structure is configured for enhancing the structural integrity of the container. Each compartment is defined at least in part by a preform. One or more preforms are assembled into a casting insert for forming the container. The casting insert includes one or more flow paths. A molten material is introduced about the insert, including into the one or more flow paths. The solidified molten material defines the external walls and the internal support structure of the container. The preform defining the compartment within the container can be retained therewithin or can be eliminated therefrom. The compartments within the container are in fluid communications, and an opening through an external wall of the container is configured for regulating fluid communications thereacross.

Description

Core Structured Components, Containers, and Methods of Casting

CROSS-REFERENCES

[0001] This application claims the benefit of U.S. Provisional Patent Application No.

61/680,070 filed August 6, 2012, U.S. Provisional Patent Application No. 61/850,087 filed February 8, 2013, and U.S. Provisional Patent Application No. 61 ,801,233 filed March 15, 2013, the contents each of which are incorporated herein by reference.

FIELD

[0002] This disclosure generally relates to casted articles and methods of casting, and more particularly relates to methods of using core structures to cast structural components with one or more cavities, including containers having one or more cavities.

BACKGROUND

[0003] In the broadest sense, a structural component can be any part that is designed to carry or bear some amount of load or weight. One type of a structural component is a containment vessel, also referred to herein more generically as a container or a tank. Containment vessels are used for storing many things, including for storing fluids such as gases. In many cases the contents of a tank will be pressurized to store a larger volume in the tank. As a simple well-known example, consumer-grade propane tanks are commonly sold storing a volume of propane gas under pressure that can be released by hand valve. Larger tanks for storing the fertilizer anhydrous ammonia are also well known. Anhydrous ammonia must be stored at high pressure and/or low temperature in order to store it in liquid form. Thus, large commercial-grade tanks must be designed to withstand the pressure exerted on the tank walls by the compressed ammonia. Another example includes containment vessels designed for storing compressed natural gas under high pressure, which can be useful for transporting a large volume of gas in a smaller, portable vessel as in the case of vehicles that operate using compressed natural gas. Of course many other examples of containers and, more generally, structural components exist.

[0004] Accordingly, in the case of containment vessels, it can be useful to design the container to withstand greater pressures so that the containers can store larger volumes of gas under higher pressures without failing. More generally, it is also often desirable to simply increase the load bearing capacity of any type of structural component. One well-known method for increasing the load bearing capacity of a structural component is to incorporate geometric curves or arcs into the design of the component. Typical foam materials having a cell structure incorporating spherically-shaped voids provide one example of such a structural component. Cylindrical gas tanks provide another example of a component incorporating a curved design. As is known, the cylindrical geometry of the tank wall more evenly distributes the load exerted by the pressurized gas inside the tank.

[0005] It will also be appreciated that load bearing capacity can be increased by simply reinforcing existing support structures. For example, cylindrical tanks generally have thick walls to provide the high tensile and rupture strengths that prevent container burst and loss of tank contents.

[0006] Casting is one well-known process that has been used to manufacture a variety of structural components. Those skilled in the art will appreciate that many other manufacturing techniques and processes are also employed to make structural components.

SUMMARY

[0007] Embodiments of the invention are generally directed to structural components that can bear some amount of a load. In some cases, embodiments structural components in the form of various containers that are capable of withstanding pressure exerted on the wall(s) of the container. Some embodiments provide new methods for casting structural components, including containers. In addition, some embodiments provide core structures and/or methods of making core structures that can be used to form cavities in the subsequent formation of a structural component such as a container.

[0008] According to one aspect, a structural component is provided. The component is cast from a molten material and includes first and second outer wall portions. An internal support structure extends between the first outer wall portion and the second outer wall portion. The structural component also includes a number of compartments positioned within the internal support structure. The internal support structure also includes multiple rectilinear support members. Each of the rectilinear support members includes a solidified material formed by a corresponding molten material flow path. The flow path for the molten material is provided by a core structure used to cast the structural component. Further, at least one of the rectilinear support members is connected between the first outer wall portion and the second outer wall portion, which enhances the structural integrity of the component. In one embodiment the rectilinear support members include multiple internal walls that are defined by the compartments and/or that define the compartments.

[0009] Some embodiments provide a container that is cast from a molten material.

According to some embodiments, the container includes an internal support structure extending through one or more compartments within the container. The support structure is formed by a molten material received within one or more flow paths of a casting insert configured for forming the container.

[0010] According to some embodiments, the container includes multiple compartments, each of which has a configuration provided at least in part by a corresponding preform forming a part of a core structure used to cast the container. The container also has an internal support structure that includes multiple rectilinear support members. The rectilinear support members include internal walls that are defined by the compartments and/or that define the compartments in the container. The container also includes an external wall that substantially encloses the internal support structure and the compartments. The external wall has a first outer wall portion and a second outer wall portion and at least one of the rectilinear support members is connected between the first outer wall portion and the second outer wall portion to enhance the structural integrity of the container.

[0011] According to some embodiments, a method for casting a structural component such as a container is provided. The method includes providing a mold having a cavity with multiple cavity walls and positioning a core structure in the mold. The core structure includes multiple preforms. The method also includes forming an external container wall by introducing molten material into an exterior flow path between one or more of the cavity walls and the core structure. The method further includes forming multiple compartments and a number of rectilinear support members by introducing the molten material into a number of interior flow paths extending between the preforms in the core structure. Forming the compartments in such a manner locates one compartment at a location of each of the preforms. The method also includes connecting the rectilinear support members between separate points on an internal surface of the external container wall and solidifying the molten material. [0012] In some embodiments a method for forming a container includes positioning a core structure, also referred to herein more generally as a casting insert, within a mold cavity. The core structure/casting insert includes a preform with a barrier layer thereabout. A molten material is introduced into the mold cavity about the casting insert. The barrier layer prevents the molten material from infiltrating into the preform. Then, the molten material is solidified such that the preform defines one or more compartments within the solidified material. The compartments include support structure extending therethrough.

[0013] According to some embodiments, a casting insert is provided for forming a structural component embodying a container. The casting insert (i.e., core structure) has adjacent preforms, each having a barrier layer there-around. The barrier layer is configured for preventing infiltration of molten material into the preforms. The core structure/casting insert further includes one or more flow paths configured for receiving a molten material between adjacent preforms. The adjacent preforms are configured to form interconnected

compartments within the container, with the compartments having a support structure extending therebetween.

[0014] Some embodiments may optionally provide some or all of the following advantages, or none at all, or other advantages not listed here.

[0015] For example, in some cases the internal walls of a structural component may form a contiguous cavity within the structural component such that the contiguous cavity includes two or more of the previously mentioned compartments. Further, in some cases the internal walls provide at least one fluid flow path within the contiguous cavity that extends through the two or more compartments. In some embodiments the compartments of a structural component are arranged in a geometric configuration corresponding to the locations of a preforms that form at least part of the core structure used to cast the structural component. The compartments can in some cases have a polyhedral shape (e.g., a cubic shape, a rectangular shape, etc.) formed according to a corresponding polyhedral shape of the preforms. In some cases a first set of the compartments has a first size and a second set of the compartments has a second size larger than the first. In addition, in some cases this second set of compartments are positioned near a middle of the structural component and the first set of compartments are arranged between the second set of compartments and an external wall of the structural component. According to some embodiments, the external wall has a non- cylindrical surface contour that corresponds to an arrangement of the first set of compartments. In some cases the compartments are positioned adjacently within the internal support structure. The structural component can have tubes connecting or positioned between, and intersecting, adjacent compartments to provide a fluid flow path between the adjacent compartments. In some cases at least one rectilinear support member is configured as a generally planer wall that extends parallel to a polyhedral surface that defines one side of a compartment.

[0016] According to some embodiments an external wall of a structural component and/or container may have a cylindrical configuration, while in some embodiments the external wall may have a non-cylindrical configuration. The rectilinear support members and the external wall can be integrally formed and include a solidified material. The external wall can also have a configuration corresponding to a molten material flow path created during casting between walls of a mold and an exterior of the core structure. In some cases, each rectilinear support member has a configuration corresponding to a molten material flow path within the core structure between adjacent preforms. The solidified material can be any one or combination of materials used in casting, including one or more of a metal, a glass, an elastomer, a confection, a thermoplastic polymer, and a thermosetting polymer. According to some embodiments, each of the compartments has a void formed in the container from removing one of the preforms from the core structure.

[0017] According to some embodiments, one or more, or each/all of the compartments include at least a portion of its corresponding preform. The preform includes a permeable storage material configured to store a fluid. For example, in some cases the storage material includes a graphite based fiber material configured to adsorb the fluid.

[0018] Methods for casting a structural component can also include retaining the preforms within the core structure after solidification, and optionally storing a fluid within a permeable storage material. In some cases a method also includes removing the preforms from within the core structure after solidification, thus configuring each compartment as a void in the container.

[0019] These and various other features and advantages will be apparent from a reading of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS [0020] The following drawings illustrate some particular embodiments of the present invention and therefore do not limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description. Some embodiments will hereinafter be described in conjunction with the appended drawings, wherein like numerals denote like elements.

[0021] FIG. 1 is a flow diagram of a method of casting a container with a core structure according to some embodiments.

[0022] FIG. 2A and 2B are perspective view of preforms with a barrier layer according to some embodiments.

[0023] FIG. 2C is a perspective view of a preform with a connecting tube according to some embodiments.

[0024] FIG. 2D is a perspective view of a row of preforms and a connecting tube cast within a translucent material according to some embodiments.

[0025] FIG. 3A is a perspective view of a preform according to some embodiments.

[0026] FIG. 3B is a perspective view of a layer of the preforms of FIG. 3 A according to some embodiments.

[0027] FIG. 3C is a perspective view of a core structure with a stacked arrangement of multiple preforms as in FIG. 3A according to some embodiments.

[0028] FIG. 4A is a perspective view of a core structure with a layer of preforms according to some embodiments.

[0029] FIG. 4B is a top view of a core structure with an arrangement of preforms of different sizes according to some embodiments.

[0030] FIG. 4C is a schematic depiction of arranging multiple preforms of different sizes into a core structure according to some embodiments.

[0031] FIGS. 5A and 5B are perspective and top views, respectively of a core structure formed from multiple arranged preforms according to some embodiments. [0032] FIG. 5C is a perspective view of an asymmetrical core structure formed from multiple arranged preforms according to some embodiments.

[0033] FIGS. 5D and 5E are a perspective cut-away view and a side view, respectively of a core structure formed from preforms of different sizes according to some embodiments.

[0034] FIG. 6 is a perspective view of a casted structural component according to some embodiments.

[0035] FIGS. 7A-7B are perspective sectional and cut-away views, respectively, of a casted container according to some embodiments.

[0036] FIG. 8A provides perspective sectional views of a container according to some embodiments.

[0037] FIG. 8B is an enlarged perspective sectional view of the container of FIG. 8A according to some embodiments.

[0038] FIGS. 9A-9F are perspective and sectional or cut-away views of multiple containers according to some embodiments.

[0039] FIGS. lOA-lOC are perspective illustrations of different containers showing relative stress loads according to some embodiments.

[0040] FIG. 11 is a flow diagram of a method of casting preforms according to some embodiments.

[0041] FIG. 12 is a flow diagram of a method of casting a container with a core structure according to some embodiments.

DETAILED DESCRIPTION

[0042] The following detailed description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the following description provides some practical illustrations for implementing some embodiments of the present invention. Examples of constructions, materials, dimensions, and manufacturing processes are provided for selected elements, and all other elements employ that which is known to those of ordinary skill in the field of the invention. Those skilled in the art will recognize that many of the noted examples have a variety of suitable alternatives.

[0043] Various new embodiments of casted preforms, casted core structures, casted structural components (e.g., containers), methods for casting structural components, methods for casting preforms and/or core structures, and related features, techniques, and details are described below. As used herein, the term "structural component" refers broadly to a part or component that can bear a load. Accordingly, a structural component can generally be considered to have an interface that receives the load and some type of support structure that supports the interface while it receives the load. Examples of structural components are numerous and evident in virtually every aspect of man-made structures. As just a few examples, foam materials used for padding or shock absorption, crash pads installed on a median that absorb the impact of a wayward vehicle on a freeway, parts of such a vehicle designed to withstand impacts, and armor plating, and ballistic armor (e.g., with void cavities filled with energy absorption gel) are all considered examples of structural components for purposes of this disclosure. In addition, various types of containers, including but not limited to containment and/or storage vessels, pressurized and non-pressurized tanks, and dry storage units are all examples of structural components. Of course a wide variety of other structural components are also contemplated although not mentioned herein.

[0044] As will be appreciated, embodiments described herein are directed to structural components that are at least in part cast by introducing a molten material into a mold and then letting the material solidify to form the desired component. Accordingly, discussion of structural components herein assumes that at least some portion of a component has been or will be casted unless otherwise specified. For example, new methods of casting various types of containers, as well as the casted containers themselves, are described herein. Further, while several embodiments are described with respect to container -type structural components, embodiments are not limited to containers. It is also contemplated that the teachings provided herein can be applied to various other types of structural components, including but not limited to any of the examples provided herein.

[0045] Turning to the drawings, FIG. 1 is a flow diagram of a method 10 that illustrates some steps in a process of casting a structural component according to some embodiments. In this case, FIG. 1 provides an overview of a method 10 for casting a container with a core structure according to some embodiments. As shown in FIG. 1, in this case multiple preforms 12 are assembled and/or arranged as a core structure, also referred to herein as casting insert. The assembled/arranged preforms 12 or core structure 14 are then positioned within the cavity 16 of a mold 18. A molten material 20, such as a molten metal or a molten polymer, is then introduced into the cavity of the mold 18 about the core structure 14. As the molten material 18 fills the cavity less the space occupied by the core structure 14, the material forms an external container wall 22 and a number of support members 24 whose dimensions and shapes are determined by flow paths around and within the core structure 14. After the mold 18 is filled, the molten material 18 is allowed to solidify, thus forming the container 26.

[0046] According to some embodiments, a thermal insulation layer 27 may be used to insulate one or more portions of the mold cavity 16 and/or core structure 14. Examples of possible thermal insulators that can be used are described in Applicant's co-pending U.S. Patent Application No. 13/840,423, filed March 15, 2013, and titled Thermal Isolation for Casting Articles, and co-pending U.S. Patent Application No. 13/836,001 , filed March 15, 2013, and titled Thermal Isolation Spray for Casting Articles. Each of the above-referenced applications are hereby incorporated by reference herein in their entirety. As described in more detail in Application Nos. 13/840,423 and 13/836,001 , the thermal insulation layer 27 (sometimes provided in the form of a blanket or applied as a spray) can allow the molten material 20 to remain in a molten state for an extended dwell time. For example, using the thermal insulation layer 27 may extend the dwell time from the introduction of the molten material 20 at least until the mold cavity 16 is filled. In another example, the insulation layer 27 may extend the dwell time from first introduction of the molten material 20 until pressurization, such as in the case of squeeze casting.

[0047] Referring back to FIG. 1, the preforms 12 and/or core structure 14 define and locate a corresponding compartment 28 at the location of each preform 12. In some cases the preforms 12 may remain within the container 26. As one example, a preform may optionally be formed from a porous or permeable material that can receive and store a fluid. In some embodiments an additional step of the method 10 includes removing the preforms 12 and/or core structure 14, thus forming a container 32 with empty compartments 30 or voids. As will be discussed, in some cases preforms/core structures can be removed from the container by washing away or burning away the preform material.

[0048] According to some embodiments, assembling and/or arranging multiple preforms to form a core structure may optionally include providing a physical connection between the preforms and/or a fluid connection between two or more of the preforms. For example, FIG. 1 illustrates the preforms 12 being connected together to form the core structure 14 with tubes 34. The tubes 34 can be hollow tubular members that physically and fluidly connect two or more adjacent preforms 12. Upon solidification, and optionally removal of the preforms 12, the tubes 34 and the compartments 30 can thus provide a contiguous cavity having a fluid flow path through portions of the cavity and container.

[0049] Continuing to refer to FIG. 1 , some embodiments also make use of a barrier layer 36 that is applied as a coating about the preforms 12 and/or core structure 14. The barrier layer 36 provides a functional seal about each preform 12, thus preventing infiltration of the molten material within the preform during casting. While in some cases portions of the barrier layer may remain in the casted containers 26, 32, in some embodiments the barrier layer 36 may break apart or disintegrate when the molten material 20 comes into contact with the layer. This may occur, for example, during squeeze casting.

[0050] FIG. 2A-2D relate to some embodiments for casting a structural component such as a container using a network of two or more tube-mounted preforms. FIGS. 2A and 2B are perspective view of preforms 200, 202 coated with a barrier layer 204, 206, respectively, according to some embodiments. Preforms as used in various embodiments can be made from a variety of materials. Examples of materials and techniques for forming some suitable preforms are disclosed in Applicant's co-owned U.S. Patent No. 8,075,827, titled "Variable- Density Preforms", issued December 13, 201 1 , the entirety of which is incorporated herein by reference. As just a few possible but not exhaustive examples, in some cases a preform such as the preforms 200, 202 shown in FIGS. 2A-2B can be formed from a composition including one or more of carbon graphite fibers, silicon carbide, SAFFIL®, and Nextel™ 6io. In some cases a preform can be made from salt, sand, or any other suitable coring material.

[0051] According to some embodiments, the preforms 200, 202 can optionally be made from a material or composition that can be removed from a container after casting is complete. For example, in some cases a preform may be made from salt or sand. After the molten material has solidified, the salt or sand preforms may be dissolved (e.g., in the case of salt) and/or rinsed away with fluid (e.g., water) through one or more fluid flow paths in the container. According to some embodiments, a preform can be formed from a material that can be disintegrated or eliminated by heating so as to define compartments that are empty. For example, in some cases a preform may have a composition including carbon or graphite fibers. After casting the container, the container and included preforms/core structure can be heated (e.g., fired) in an oxidizing environment so as to form carbon dioxide that can escape through one or more flow paths in the container.

[0052] In certain embodiments, one or more preforms can have a composition that is permeable and/or porous, thus enabling the preform to remain within the container after casting and during use. In this situation compartments within the casted container may be formed simply by preforms displacing the molten material until solidification to create spaces within the container free of the molten material. Thus, the preforms may remain within the casted structural component and form part of the compartments within the casting. As just one possible example, preforms with sorbent capabilities can be used to form compartments within a pressurized gas tank such as a compressed natural gas (CNG) tank. One example of a possible preform includes a graphite -based fiber preform that adsorbs methane from compressed natural gas stored in a container.

[0053] According to some embodiments, preforms may also remain within a container or other structural component post-casting if the preforms add any other desired functionality to the compartments and/or structural component. In certain embodiments, for example, preforms may be left within a structural component for additional structural properties such as absorption of force as in the case of ballistic and other uses.

[0054] As shown in FIGS. 2A and 2B, the preforms 200, 202 are formed as cuboids, having a rectangular, three-dimensional shape. In general, embodiments may incorporate preforms having one of a variety of different shapes. Some possible examples are cubic shapes, rectangular shapes, pyramidal shapes, rhomboidal shapes, and other shapes. According to some embodiments, a preform may generally be defined as having a polyhedral shape. In some cases providing preforms in a polyhedral shape such as a cuboid or rhomboid can increase the compartment or void density within a structural component such as a container. For example, the shape of the preform may be chosen to maximize void density approaching 100%. These types of preform configurations can thus provide an advantage over cylindrical and/or spherical shapes, which inherently have lower density arrangements, since a greater void density provides a larger volume for storing fluids and less material leading to less weight. [0055] FIG. 2D is a perspective view of a row of preforms 210 and a connecting tube 212 cast within a translucent material 214 according to some embodiments. As shown in FIG. 2D and elsewhere, in several embodiments it is contemplated that two or more preforms can be connected or arranged (e.g., stacked) together to form a network or system of preforms. Such an arrangement of preforms is also referred to as a casting insert or a core structure herein since the preforms are inserted into the mold during the casting process and are used to form one or more compartments at the core of the structural component.

[0056] FIG. 2D illustrates how the preforms 210 are arranged and connected to form a core structure 216. The preforms 210 are connected to one another in a spaced-apart relationship by the connecting tube 212, which in this case also provides an inter-compartmental flow path extending between preforms 210 and ultimately between compartments formed in the casted container. As such, interconnected preforms 210 also define interconnected compartments within a container. In some embodiments, inter-compartmental flow paths are conduits or ducts configured for fluid communications between interconnected

compartments.

[0057] In certain embodiments, support tubes 212 can include an impermeable external surface for preventing infiltration of the molten material into the support tube 212 and corresponding flow path. For example, the support tube 212 can be formed from a hollow rod for connecting adjacent preforms to one another. FIG. 2C illustrates one example of a support tube/rod 212 extending through the preform 210. In some cases rods such as rod 212 include fill and egress holes 220, and extend through a network of preforms, thus forming a lattice-type structure of rods. (See, for example, FIG. 6.) In some cases the rods may be coated with a barrier layer or be otherwise impermeable. After forming such a container and removing the preforms (or maintaining the preforms), the rods may be left within the container, connecting adjacent compartments such that the fill and egress holes 220 within the network of rods/tubes provide a desired inter-compartmental flow path between compartments within the container.

[0058] While FIGS. 2C and 2D illustrate a single preform 210 and a series of three preforms 210, with a support tube 212 extending through the preforms, this should not be considered as a limitation of any sort. In some embodiments, one, two, or more preforms can be placed in a spaced-apart relationship along one single tube/rod so as to define one or more flow paths between adjacent preforms. Two or more preforms positioned adjacent one another on a single rod can be considered as pieces arranged on a skewer and/or arranged as sheesh-kebob.

[0059] In certain embodiments, the tubes can be removed before, during or after the process of eliminating preforms and/or the introduction of the molten material. Likewise, the tubes can be removed before, during or after the solidification of the molten material. In some embodiments in which the tubes are not impervious, the external surface of the tubes can be coated with an impermeable barrier so as to prevent the infiltration of the molten material into the tube and thereby hinder fluid communications between interconnected

compartments.

[0060] Further, in certain embodiments, only adjacent preforms may be connected to one another with one single bar extending between opposed sides of the adjacent preforms 24. In some embodiments, inter-compartmental flow paths are defined by an elongated hollow conduit, e.g., a tubing. In some embodiments, the conduit may have an impermeable exterior surface. In certain embodiments, the conduit may have openings through its external surface so as to facilitate fluid communications between the hollow of the conduit and the preform through which it extends. The ends of the conduit may be open or closed.

[0061] Returning to FIGS. 2A and 2B, in certain cases, preforms may have a porosity that ranges from being impervious to being highly porous depending upon the type of material used. In cases in which preforms exhibit some degree of porosity, a barrier layer such as the barrier layer 204 or 206 can be applied to the external surfaces of a preform so as to prevent or minimize the infiltration of the molten material into preforms. The barrier layer may not be needed if a preform is impermeable in some cases.

[0062] In some embodiments, the barrier layer can be applied prior to and/or after assembling preforms 200, 202 into the casting insert shown in FIG. 2D. For instance, in some cases the barrier layer application process can be an integral part of the process for manufacturing the preforms. In certain embodiments, the barrier layer can be applied after manufacturing the preforms and prior to assembling them into a core structure or casting insert. In some embodiments, the barrier layer can be applied after preforms have been assembled into a core structure. In certain embodiments, casting inserts and/or preforms may additionally be sintered after the barrier layer has been applied. Firing the preforms/insert to sinter can in some cases be useful for pressurized casting methods, such as squeeze casting, but may not necessarily be needed or desired for low pressure casting methods such as gravity casting or other low pressure methods.

[0063] In some embodiments, the barrier layer can be sprayed onto the preforms. In other embodiments, the barrier layer can be formed by submerging the preforms in a bath or a vat containing a liquid or a slurry of the barrier layer material. In certain embodiments, the density and/or porosity of the barrier layer can be varied along the direction of its thickness extending away from the external surfaces of the preforms. For instance, in some embodiments, the density and/or porosity of the barrier layer can increase or decrease with distance extending away from the external surfaces of preforms. In some embodiments, a first density of the barrier layer at a first location proximate or adjacent to or coincident with an external surface of preform can be different from a second density of the barrier layer at a second location space apart from the first location. In certain embodiments, a first porosity of the barrier layer at a first location proximate or adjacent to or coincident with the external surface of preform can be different from a second porosity of the barrier layer at a second location space apart from the first location. In a non-limiting exemplary embodiment, the first porosity can be substantially less than the second porosity. In other words, the barrier layer can be relatively more impervious at the first location than at the second location. As such, in some cases at least a portion of the molten material introduced about preform can be permitted to infiltrate at least some distance into the barrier layer.

[0064] FIG. 3A is a perspective view of a single preform 300 according to some

embodiments, while FIG. 3B is a perspective view of a layer 302 of the preforms 300 of FIG. 3A according to some embodiments. FIG. 3C is a perspective view of a core structure 304 with a stacked arrangement of multiple preforms 300 as in FIG. 3 A according to some embodiments. FIGS. 3A-3C illustrate an alternate embodiment of preforms 300 used for forming the core structure 304 or casting insert. As will be apparent from the following description, core structure 304 is formed by interconnecting preforms 300 in a manner similar to that used with Lego™ building blocks. Adjacent preforms 300 define a pair of opposing external surfaces with a flow path extending therebetween. In some embodiments, one such external surface 340A includes at least one protrusion 360A configured for being received by and retained within a corresponding complementary recess, such as a recess on an opposite side of the preform. The preforms are interconnected to one another by inserting protrusion 360 into the recess of the adjacent preform. The other preforms are interconnected in a similar manner. As will be apparent, a plurality of preforms can be interconnected to form a three-dimensional insert core structure 304. Once the preforms 300 have been assembled to form core structure 304, the preforms and protrusions can optionally be eliminated (e.g., after applying a barrier layer) so as to respectively define or form compartments within a container and inter-compartmental flow paths between adjacent compartments.

[0065] As used with respect to FIGS. 3A-3C, the term "casting insert" refers to an arrangement of multiple preforms that are spaced apart from one another so as to define one or more molten material flow paths 350. In this example, the term casting insert refers to the entire or whole structure of connected preforms, though in other examples a casting insert may be provided in a variety of sizes and configurations of one, two, or more preforms or other sub-inserts that are joined together and/or separately positioned within a mold cavity during casting.

[0066] FIG. 4A is a perspective view of another example of a core structure 400 formed from a layer 402 of preforms 404 according to some embodiments. It should be appreciated that many different arrangements of preforms are possible when forming core structures. FIG. 4B is a top view of a core structure 420 with an arrangement of preforms 422, 424 of different sizes according to some embodiments. FIG. 4C is a schematic depiction of arranging multiple preforms of different sizes into a core structure 450 according to some embodiments. FIGS. 5A and 5B are perspective and top views, respectively of a core structure 500 formed from multiple arranged preforms 502 according to some embodiments. FIG. 5C is a perspective view of an asymmetrical core structure 520 formed from multiple arranged preforms 522 according to some embodiments. FIGS. 5D and 5E are a perspective cut-away view and a side view, respectively of a core structure 550 formed from preforms 552, 554 of different sizes according to some embodiments. FIG. 5E shows within the dotted line 556 how the larger preforms 554 are visible from the side view.

[0067] FIGs. 6-9F illustrate various embodiments of possible containers made with, e.g., some of the preforms previously described.

[0068] Referring to FIGS. lOA-lOC, in some cases FEA analysis can be used to optimize the parameters of a container, such as these parameters: Inner cell size, Outer cell size, Inner wall thicknesses, Outer wall thickness, Inter-cell hole diameter, Volume of material, Volume of enclosed space, Ratio of volume of space to material, Minimize weight of material, Corner Radii. This can be useful to minimize stresses on the containers.

[0069] A two-step process can be used to find an efficient model (e.g., for a multi-celled system) in some cases. The two steps are: 1) Numerical Optimization; and 2) Finite Element Analysis. Using basic geometry, an explicit formula for the volume of material and the volume of contained space can be found in terms of several parameters.

[0070] Method of Steepest Ascent: starting with an initial set of parameter values, the gradient of is calculated, which gives the direction in which increases the greatest

[0071] This method can be used to find a series of parameter values that result in an ever- increasing value for , giving precedence to parameters that have the greatest influence.

[0072] Using FEM, the stress of each model is then calculated.

[0073] Example:FEM models created on Abaqus 6.9 using Python script

[0074] Aluminum 7075 properties used:

• 10E6 psi Young's modulus

• 0.33 Poisson's ratio

• 68 ksi yield strength

• 0.102 lb/in³ density

[0075] Boundary conditions were used for symmetry, thus representing an entire 3x3x3- celled model. Uniform pressure of 3600 psi was applied to all inner surfaces of the model shown in FIG. 10 at number 1000. The analysis used quadratic hexahedral and wedge elements, C3D20R and C3D15, with a Seed size: 0.03 in.

[0076] Exemplary model details:

• Cell size: 1.033 in

• Fillet radius: 0.168 in

• Inter-cell hole radius: 0.112 in

• Outer wall thickness: 0.102 in

• Inner wall thickness: 0.106 in

• Volume of material: 15.30 in³

• Volume of enclosed space: 28.13 in³

• Weight of material: 1.56 lb

• Ratio of volume of space to material: 1.86 • This is a 6% increase compared to previous models

• Max Mises stress is about 68 ksi

[0077] Steps to follow:

• Develop a Python script to generate models with varying cell sizes (such as the model shown) and run an optimization algorithm to refine models and cell structure

• Consider alternative methods of optimization that better incorporate FEM results

• Internal structure can have larger cell size than external cells. An FRG optimization of open area.

[0078] Referring to FIG. 1 1 , a method of casting preforms is illustrated.

[0079] Referring to FIG. 12, in some embodiments, the molten material introduced about casting insert 22 can be one or more of a metal, glass, an elastomer, a confection, a thermoplastic polymer, a thermosetting polymer, or any combinations thereof. In certain embodiments, the molten material can be introduced by one or more of the several methods known in the art of casting, which methods include but are not limited to injection molding, die casting, squeeze molding, squeeze casting, gravity casting, or any other technique(a) as may become apparent to one skilled in the art. In some embodiments, an adequate amount of pressure can be applied to the molten material so as to break apart at least a portion of the barrier layer under pressure.

[0080] As previously described, certain embodiments of container 10 can be used for storing pressurized gas, i.e., for storing gas at a pressure substantially greater than the atmospheric pressure. In some embodiments, compressed natural gas can be stored within preforms 14 and/or within compartments 14 of container 10 at an elevated pressure. In other

embodiments, preforms 14 and/or compartments 14 can be used for storing one or more of a fire suppression material, an energy absorbing gel, a polymer, a liquid, a powder, a foam, or any combinations thereof.

[0081] In accordance with an embodiment, a method for forming a container includes positioning a casting insert 322 within mold cavity 28 as illustrated in FIGS. 3A and 3B. As previously described, insert 322 includes one or more preforms 24 having a barrier layer on the external surfaces thereof and one or more flow paths 26 between adjacent preforms 24. Next, the molten material is introduced into mold cavity 28 about the entirety of insert 322. As such, the molten material will also flow into each flow path 26. As previously described, one or more of the several methods known in the art can be used for introducing the molten material about insert 322. Also as previously described, the barrier layer about preforms 24 prevents the molten material from infiltrating preforms 24. The molten material within the flow paths 26 and about insert 322 is then solidified so as to form the container encasing preforms 24. As such, the solidified material about insert 322 defines external walls 18 of a container (e.g., container 10 in FIGS. 1-2), and the solidified material within flow paths 26 defines support structure within the container. One such embodiment has been previously described.

[0082] In some cases positioning a casting insert within a mold cavity can involve the use of additional preforms to support and orient the casting insert within the mold cavity in a desired position. For example, one, two, or more sacrificial preforms may be placed on the bottom surface of the mold cavity with the casting insert positioned on top of the sacrificial preforms to suspend the casting insert off of the bottom surface of the mold cavity. During the casting process, molten material may infiltrate the sacrificial preforms, thus forming an integral cast structure (e.g., possibly including the preforms) below the casting insert. Such as technique can be used, for example, to form the bottom wall of a container.

[0083] In some embodiments, compartments 14 are formed by disintegrating or removing preforms 24 from within a container after the molten material has solidified. In other embodiments, compartments 14 are formed by disintegrating or removing preforms 24 from within casting insert 322. This can be done either before or after the molten material has solidified. For instance, preforms 24 can be disintegrated or removed before the molten material is introduced into mold cavity 28 or before placing insert 322 in mold cavity 28. Removing the preforms 24 in this manner can leave behind the barrier layer still maintaining the general shape of the now removed preforms.

[0084] In some embodiments the preforms may be "burned" away by heating the casted container to a sufficiently high temperature. As just one example, in the case that preforms are made from a carbon-based material (e.g., graphite-based fiber material), the casted container and contents can be heated to 900°F such that the preforms burn releasing oxygen and carbon dioxide, which can be vented. As mentioned above, some preforms may be made from sand or salt, in which case the preforms may be washed or shaken out, respectively. Sand and/or salt preforms may be useful in casting containers and other articles in which the casting is thinner, such as a structural backer for armor.

[0085] Thus, embodiments of the invention are disclosed. Although the present invention has been described in considerable detail with reference to certain disclosed embodiments, the disclosed embodiments are presented for purposes of illustration and not limitation and other embodiments of the invention are possible. One skilled in the art will appreciate that various changes, adaptations, and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A structural component cast from a molten material, the structural component comprising:

a first outer wall portion;

a second outer wall portion;

an internal support structure extending between the first outer wall portion and the second outer wall portion; and

a plurality of compartments positioned within the internal support structure;

wherein the internal support structure comprises a plurality of rectilinear support members, each of the rectilinear support members comprising a solidified material formed by a corresponding molten material flow path provided by a core structure used to cast the structural component;

wherein at least one of the rectilinear support members is connected between the first outer wall portion and the second outer wall portion to enhance a structural integrity of the structural component; and

wherein the rectilinear support members comprise a plurality of internal walls defined by the compartments.

2. The structural component of claim 1, wherein the internal walls form at least a first contiguous cavity within the structural component, and wherein the first contiguous cavity comprises two or more of the compartments.

3. The structural component of claim 2, wherein the internal walls further provide at least one fluid flow path within the first contiguous cavity through the two or more compartments.

4. The structural component of claim 1, wherein the compartments are arranged in a geometric configuration corresponding to the locations of a plurality of preforms forming at least part of the core structure used to cast the structural component.

5. The structural component of claim 4, wherein the compartments have a polyhedral shape formed according to a corresponding polyhedral shape of the preforms.

6. The structural component of claim 4, wherein a first set of the compartments has a first size and a second set of the compartments has a second size larger than the first.

7. The structural component of claim 6, wherein the second set of compartments are positioned near a middle of the structural component and the first set of compartments are arranged between the second set of compartments and an external wall of the structural component.

8. The structural component of claim 7, wherein the external wall has a non-cylindrical surface contour corresponding to an arrangement of the first set of compartments.

9. The structural component of claim 4, wherein the compartments are positioned adjacently within the internal support structure, and further comprising a plurality of tubes, each tube positioned between and intersecting adjacent compartments to provide a fluid flow path between the adjacent compartments.

10. The structural component of claim 1, wherein at least one rectilinear support member is configured as a generally planer wall extending parallel to a polyhedral surface defining one side of a compartment.

11. A container cast from a molten material, the container comprising:

a plurality of compartments, each compartment having a configuration provided at least in part by a corresponding preform forming a part of a core structure used to cast the container;

an internal support structure comprising a plurality of rectilinear support members, the

rectilinear support members comprising a plurality of internal walls defined by the plurality of compartments; and

an external wall substantially enclosing the internal support structure and the plurality of compartments;

wherein the external wall comprises a first outer wall portion and a second outer wall portion; and

wherein at least one of the rectilinear support members is connected between the first outer wall portion and the second outer wall portion to enhance a structural integrity of the container.

12. The container of claim 11, wherein the external wall has a non-cylindrical

configuration.

13. The container of claim 11, wherein the rectilinear support members and the external wall are integrally formed and comprise a solidified material, wherein the external wall has a configuration corresponding to a molten material flow path created during casting between walls of a mold and an exterior of the core structure, and wherein each rectilinear support member has a configuration corresponding to a molten material flow path within the core structure between adjacent preforms.

14. The container of claim 13, wherein the solidified material comprises one or more of a metal, a glass, an elastomer, a confection, a thermoplastic polymer, and a thermosetting polymer.

15. The container of claim 11, wherein each of the plurality of compartments comprises a void formed in the container from removing one of the preforms from the core structure.

16. The container of claim 11, wherein each of the plurality of compartments comprises at least a portion of its corresponding preform, the corresponding preform comprising a permeable storage material configured to store a fluid.

17. The container of claim 16, wherein the storage material comprises a graphite based fiber material configured to adsorb the fluid.

18. A method for casting a container, comprising:

providing a mold comprising a cavity having a plurality of cavity walls;

positioning a core structure in the mold, the core structure comprising a plurality of preforms; forming an external container wall by introducing molten material into an exterior flow path between one or more of the cavity walls and the core structure;

forming a plurality of compartments and a plurality of rectilinear support members by

introducing the molten material into a plurality of interior flow paths extending between the plurality of preforms in the core structure, thereby locating one of the compartments at a location of each of the preforms and connecting the rectilinear support members between separate points on an internal surface of the external container wall; and

solidifying the molten material.

19. The method of claim 18, further comprising retaining the preforms within the core structure after solidification, wherein the preforms comprise a permeable storage material configured to store a fluid.

20. The method of claim 18, further comprising removing the preforms from within the core after solidification, thus configuring each compartment as a void in the container.