Lattice Support Structures
The present disclosure is drawn to a lattice support structure, comprising a plurality of fiber-based cross supports intersecting one another to form a multi-layered node. The multi-layered node can be consolidated within a rigid mold in the presence of resin, heat, and pressure. In another embodiment, a lattice support structure can comprise a first cross support comprising fiber material; a second cross support comprising a fiber material, said second cross support intersecting the first cross support; and multi-layered nodes located where the first cross support intersects the second cross support. The multi-layered nodes can comprise at least two layers of the first cross support separated by a least one layer of the second cross support. Also, one of the first cross support or the second cross support can be curved from node to node.
This application is a continuation application of U.S. patent application Ser. No. 13/692,879, filed Dec. 3, 2012 which is a continuation application claiming the benefit of U.S. patent application Ser. No. 12/542,442, filed Aug. 17, 2009, entitled, “LATTICE SUPPORT STRUCTURES,” which claims the benefit of U.S. Provisional Patent Application No. 61/089,124,” filed on Aug. 15, 2008, entitled, “THREE-DIMENSIONAL GEO-STRUT STRUCTURE AND METHOD OF MANUFACTURE, each of which are incorporated in their entirety by reference and made a part hereof.
BACKGROUNDStructural supports, including lattice-type structural supports, have been developed for many applications which provide high strength performances, but benefit from the presence of less material. In other words, efficient structural supports can possess high strength, and at the same time, be low in weight resulting in high strength/weight ratios. Truss systems have been pursued for many years and continue to be studied and redesigned by engineers with incremental improvements.
In the field of carbon fiber lattice support structures, a primary issue concerning such systems relates to the construction of joints, coupling members of the system together forming a single larger unit. Approaches to coupling the lattice members such as weaving, twisting, mechanical fastening, bypassing of nodes, or the like, have provided marginal results regarding strength performances of the resulting structures. Thus, it would be desirable to provide a lattice support structure that has exceptional node strength and a high level of structural integrity using fiber-based materials.
Additional features and advantages of the invention will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the invention; and, wherein:
Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.
DETAILED DESCRIPTIONThe following detailed description of representative embodiments of the present disclosure makes reference to the accompanying drawings, which form a part hereof and in which are shown, by way of illustration, various representative embodiments in which the teachings of the disclosure can be practiced. While these embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments can be realized and that various changes can be made to the disclosure without departing from the spirit and scope of the present invention. As such, the following detailed description is not intended to limit the scope of the disclosure as it is claimed, but rather is presented for purposes of illustration, to describe the features and characteristics of the present disclosure, and to sufficiently enable one skilled in the art to practice the disclosure. Accordingly, the scope of the present invention is to be defined by the appended claims.
In accordance with this, a lattice support structure can comprise a plurality of fiber-based cross supports intersecting one another to form a multi-layered node. The multi-layered node can be consolidated within a groove of a rigid mold in the presence of resin, heat, and pressure. In one embodiment, the cross supports can have a thickness where the multi-layered node is thinner than the sum of the thickness of each cross support at the multi-layered node.
In another embodiment, a lattice support structure can comprise a first cross support comprising fiber material, and a second cross support comprising a fiber material, where the second cross support intersects the first cross support. The lattice support structure can also include multi-layered nodes located where the first cross support intersects the second cross support. The multi-layered nodes can comprise at least two layers of the first cross support separated by a least one layer of the second cross support. Additionally, at least one of the first cross support or the second cross support can be curved from node to node.
It is noted that when referring to a “multi-layered” node, what is meant is that the cross supports are not merely stacked on top of one another, but rather, a first individual cross support has multiple layers with one or more layer(s) of material from other cross supports therebetween. Thus, in order to be “multi-layered, there must be at least one cross support or layer of at least one cross support that is between at least two layers of another cross support. Typically, however, each cross support of the node is layered with other cross support layers therebetween (as shown hereinafter in
It is also notable that the present disclosure provides lattice support structures or fiber-based composite articles. Examples of specific methods for the fabrication thereof and related systems, as well as solid mandrels used to form such structures, can be found in Applicants' copending U.S. patent applications filed Aug. 17, 2009 under Attorney Docket Nos. 3095-003.NP, 3095-004.NP, and 3095-006.NP, each of which is incorporated herein by reference in its entirety.
In further detail with respect to embodiments of the present disclosure, several figures provided herein setting forth additional features of the lattice support structures of the present disclosure are provided.
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With specific reference to curing, in one embodiment, the curing process comprises applying 90-150 psi nitrogen gas at 250-350° F. for a soak period of about 10 to 240 minutes depending on the size of the part and its coinciding tooling. In this embodiment, the cross supports with layered and interleaved nodes can be applied to a solid mandrel and wrapped with a membrane or bag. Once in place, the pressure from the ambient curing gas provides an even press through the bag on the entire part, thus curing and consolidating the multi-layered nodes.
In further detail with respect to the embodiments shown in
Additional structural supports can also be included in the lattice support structure. Components which are straight from junction to junction may be included to intersect multi-layered nodes parallel to the centerline to form unidirectional members (e.g. longitudinal cross supports). Components, which can be curved or straight, can also be added circumferentially to intersect with the multi-layered nodes along the length of the lattice support structure. These circumferential cross supports can be added to increase internal strength of the structure. These additional members may be added to intersect at the multi-layered nodes, but do not necessarily need to intersect the nodes formed by the helical cross supports crossing one another, e.g. they may cross at areas between helical-helical nodes. In other words, the longitudinal cross supports and/or the circumferential cross supports may form common multi-layered nodes with helical-helical formed multi-layered nodes, or can form their own multi-layered nodes between the helical-helical formed multi-layered nodes. In either case, the multi-layered nodes can still be formed using filament layering. The count of helical members compared to other members is flexible in certain embodiment to allow for multi-layered nodes to occur only as lattice support structures intersect in a given location, or to allow for multiple node locations composed of two or more, but not all of the members in the structure. The capability of such a design allows versatility in the number of helical cross supports, the coil density, as well as the number of multi-layered nodes or intersections with axial, radial, or lateral components. As a general principle, the more strength desired for an application, the higher the coil density; whereas, the less strength desired, the fewer coils and wider the wrap length per coil may be present.
Structural supports may be covered with a material to create the appearance of a solid structure, protect the member or its contents, or provide for fluid dynamic properties. The current disclosure is therefore not necessarily a traditional pipe, rope, coil, spring, or solid shaft, neither is it a reinforcement for a skin cover. Even though the structures disclosed herein are relatively lightweight, because of its relative strength to weight ratio, these lattice support structures are strong enough to act as stand-alone structural units. Further, these structures can be built without brackets to join individual lattice support structures.
In accordance with one embodiment, the present disclosure can provide a lattice structure where individual supports structures are wrapped with uni-directional tow, where each helical cross support, for example, is a continual strand. Further, it is notable that an entire structure can be wrapped with a single strand, though this is not required. Also, the lattice support structures are not weaved or braided, but rather, can be wrapped layer by layer where a leaving structure is created in the nodes. Thus, where the helical cross supports intersect one another and/or one or more longitudinal and/or circumferential cross supports, these intersections create multi-layered nodes of compounded material which couple the members together. In one embodiment, the composite strand does not change major direction at these multi-layered nodes to form any polyhedral shape when viewed from the axial direction.
It is also noted that these lattice support structures can be formed using a solid mandrel, having grooves embedded therein for receiving filament when forming the lattice supports structure. Being produced on a mandrel allows the cross supports of the structural unit to be round, triangular or square or any sectional form of these including but not limited to rounding one or more corners. For production, the filaments are wrapped around a break-away mandrel generally conforming to the desired patterns of the members and providing a solid geometric base for the structure during production. Though a secondary wrap, e.g., KEVLAR, may be applied once the structure has been cured or combined with the primary fibers before cure, consolidation of members can be achieved through covering the uncured structure with a bagging system, creating negative pressure over at least the multi-layered nodes, and running it through an autoclave or similar curing cycle. This adds strength through allowing segments of components to be formed from a continuous filament, while also allowing the various strands in a single member to be consolidated during curing.
Turning now to more specific detail regarding consolidation of the multi-layered nodes, it has been recognized that the closer the fibers are held together, the more they act in unison as a single piece rather than a group of fibers. In composites, resin can facilitate holding the fibers in close proximity of each other both in the segments of the cross supports themselves, and at the multi-layered nodes when more than one directional path is being taken by groups of unidirectional fibers are layered. In filament winding systems of the present disclosure, composite tow or tape (or other shaped filaments) can be wound and shaped using a solid mandrel, and then the composite fibers forced together using pressure. Under this pressure, heat can be used to fuse the multi-layered nodes, generating a tightly consolidated multi-layered node. Thus, the multi-layered node is held in place tightly using pressure, and under pressure, the multi-layered node (including the filament or tow material and the resin) can be heat fused or cured, making the multi-layered node more highly compacted and consolidated than other systems in the prior art. Further, by using a rigid mandrel with specifically cut paths for the unidirectional fiber to be laid into, the multi-layered nodes are held tight during the consolidation process. Industry-standard bags, polyurea-based products, or other bagging materials placed over the fibers can act as a pressure medium, pushing the fibers into the grooves of the solid mandrel and removing any voids which may occur by other methods. As a result, high levels of consolidation (90-100% or even 98-100%) can be achieved. In other words, porosity of the consolidated material providing voids and weak spots in the structure are significantly reduced or even virtually eliminated. In short, consolidation control using a rigid mandrel, pressure over the wound filament or fibers, and resin/heat curing provides high levels of consolidation that strengthen the lattice as a whole.
In addition, there are other advantages of the system described herein, namely the ability to manipulate the cross-sectional geometry of the cross sectional shape of the individual cross supports. As a function of the solid mandrel and the silicone, VacuSpray 20, or other similar materials, forcing the fibers into the cut grooves allows for the geometry of the cross supports to be modified in cross section. Any geometry which can be applied to the grooves of the rigid mandrel can be used to shape resulting cross supports and can range from square/rectangular to triangular, half-pipe, or even more creative shapes such as T-shape cross sections. This provides the ability to control or manipulate the moment of inertia of the cross support members. For example, the difference in inertial moments of a flat unit of about 0.005″ thickness and a T-shaped unit of the same amount of material can reach up to and beyond a factor of 200. With the use of a solid mandrel, pressure application, and resin/temperature curing, measurement has shown that geometric tolerances can be kept at less than 0.5%.
The above detailed description describes the disclosure with reference to specific representative embodiments. However, it will be appreciated that various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the appended claims. The detailed description and accompanying drawings are to be regarded as merely illustrative, rather than as restrictive, and all such modifications or changes, if any, are intended to fall within the scope of the present disclosure as described and set forth herein. More specifically, while illustrative representative embodiments of the invention have been described herein, the present invention is not limited to these embodiments, but includes any and all embodiments having modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations and/or alterations as would be appreciated by those in the art based on the foregoing detailed description. The limitations in the claims are to be interpreted broadly based on the language employed in the claims and not limited to examples described in the foregoing detailed description or during the prosecution of the application, which examples are to be construed as non-exclusive. Also, any steps recited in any method or process claims can be executed in any order and are not limited to the order presented in the claims.
Claims
1. A lattice support structure, comprising a plurality of fiber-based cross supports intersecting one another to form a multi-layered node, said multi-layered node being consolidated within a groove of a rigid mold in the presence of resin, heat, and pressure, wherein said multi-layered node comprises at least two layers of the cross supports.
2. The lattice support structure of claim 1, wherein each of said cross supports have a thickness, and wherein said multi-layered node is thinner than the sum of the thickness of each cross support at the multi-layered node.
3. The lattice support structure of claim 1, wherein the multi-layered node comprises multiple layers of all of the cross supports intersecting to form the node.
4. The lattice support structure of claim 1, further comprising a plurality of multi-layered nodes, each multi-layered node formed from a plurality of fiber-based cross supports intersecting one another, at least one of said cross supports being layered at each of the plurality of multi-layered nodes.
5. The lattice support structure of claim 4, wherein the at least one cross support is curved between two multi-layered nodes.
6. The lattice support structure of claim 4, said lattice support structure having a generally cylindrical shape, and comprising at least one helical cross support.
7. The lattice support structure of claim 6, further comprising a second helical cross support.
8. The lattice support structure of claim 7, wherein the helical cross support intersects the second helical cross support to form the multi-layered node.
9. The lattice support structure of claim 8, wherein the helical cross support intersects the second helical cross support to form a plurality of multi-layered nodes.
10. The lattice support structure of claim 6, further comprising a longitudinal cross support that intersects the helical cross support to form the multi-layered node.
11. The lattice support structure of claim 10, wherein the longitudinal cross support intersects the helical cross support to form a plurality of multi-layered nodes.
12. The lattice support structure of claim 6, further comprising a circumferential cross support that intersects the helical cross support to form the multi-layered node.
13. The lattice support structure of claim 1, wherein at least three cross supports intersect at the multi-layered node.
14. The lattice support structure of claim 13, wherein at least three cross supports each include at least two layers at the multi-layered node.
15. The lattice support structure of claim 1, wherein the multi-layered node has increased surface area along a top surface of the lattice support structure compared to a bottom surface of the lattice support structure.
16. The lattice support structure of claim 1, wherein the fiber material includes carbon fiber.
17. The lattice support structure of claim 1, wherein the fiber material includes fiber glass.
18. (canceled)
19. The lattice support structure of claim 1, wherein the fiber material is composited with a resin.
20. The lattice support structure of claim 1, wherein the rigid mold is a grooved mandrel.
21. A lattice support structure, comprising:
- a) a first cross support comprising fiber material;
- b) a second cross support comprising a fiber material, said second cross support intersecting the first cross support; and
- c) multi-layered nodes located where the first cross support intersects the second cross support, said multi-layered nodes comprising at least two layers of the first cross support separated by at least one layer of the second cross support,
- wherein at least one of said first cross support or said second cross support is curved from node to node.
22-45. (canceled)
Type: Application
Filed: Sep 24, 2013
Publication Date: Jun 5, 2014
Inventors: Erich A. Wilson (Provo, UT), Michael D. Ridges (American Fork, UT), Michael D. Kipp (Highland, UT)
Application Number: 14/035,703
International Classification: E04C 3/28 (20060101);