US20200270864A1

US20200270864A1 - Truss structure

Info

Publication number: US20200270864A1
Application number: US16/722,667
Authority: US
Inventors: Jordan W. Oldroyd; Jonathan J. Curtis; Carter J. Smith; Nathan D. Rich; David W. Jensen
Original assignee: Isotruss Industries; Isotruss Industries LLC
Current assignee: Isotruss Industries; Isotruss Industries LLC
Priority date: 2017-03-06
Filing date: 2019-12-20
Publication date: 2020-08-27
Also published as: US20180251980A1; US10557267B2; US20180251979A1; USD970754S1; US10180000B2; WO2018165193A1; US20180258642A1

Abstract

A truss structure may include a plurality of load bearing members, or force members, that are joined at a plurality of nodes to define a load bearing structure. The truss structure may include a plurality of longitudinal members extending in parallel along a longitudinal length of the truss structure, and a plurality of transverse members, joined to the plurality of longitudinal members at nodes, and extending between the plurality of longitudinal members. The plurality of transverse members may provide buckling support to the plurality of longitudinal members, so that an axial load, or compressive load, or buckling load, may be effectively carried by the truss structure.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. application Ser. No.15/913,836, filed on Mar. 6, 2018, which claims priority to U.S. Provisional Application No. 62/467,656, filed on Mar. 6, 2017, the disclosures of which are incorporated by reference herein in their entirety.
This application is related to application Ser. No.15/913,832, filed on Mar.6, 2018, the disclosure of which is incorporated by reference herein in its entirety.

FIELD

This document relates, generally, to truss structures.

BACKGROUND

A truss structure may include a plurality of load bearing members, or force members, that are joined at a plurality of nodes to define a load bearing structure. A truss structure may be employed in situations in which a support structure is to bear a considerable load across a relatively extensive span, and in a situation in which weight of the support structure itself may affect the performance of the support structure.

SUMMARY

In one aspect, a three-dimensional (3D) load bearing structure may include a transverse frame including a plurality of transverse members sequentially arranged so as to define a plurality of 3D polyhedral structures arranged in a helical pattern along a longitudinal direction of the load bearing structure, and a plurality of longitudinal members integrally coupled with the transverse frame. The plurality of longitudinal members may be arranged in parallel to a central longitudinal axis of the load bearing structure, and extend longitudinally along a length of the transverse frame. Each longitudinal member of the plurality of longitudinal members may be integrally coupled to a corresponding outer peripheral portion of each 3D polyhedral structure of the plurality of polyhedral structures defined by the plurality of transverse members of the transverse frame.
In another aspect, a method may include forming a node joining a longitudinal member of a truss structure with a transverse member of the truss structure, the transverse member defining a portion of a helical structure of the truss structure. Forming a node may include forming a first section of the node, including arranging fibers of a material of the longitudinal member and fibers of a material of the transverse member in a first pattern, and forming a second section of the node, the second section being adjacent to the first section, including arranging remaining fibers of the material of the longitudinal member and remaining fibers of the material of the transverse member in a second pattern. The second pattern may be different from the first pattern.
The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view, FIG. 1B is a side view, FIG. 1C is an isometric view, and FIG. 1D is an axial end view, of an example truss structure, in accordance with implementations described herein.

FIGS. 2A-2H illustrate an exemplary sequential application of three dimensional polyhedral structures to a longitudinal frame formed by a plurality of longitudinal members to form an example truss structure, in accordance with implementations described herein.

FIG. 3A is a perspective view, FIG. 3B is a side view, FIG. 3C is an isometric view, and FIG. 3D is an axial end view, of an example truss structure, in accordance with implementations described herein.

FIG. 3E illustrates an example longitudinal member of an example truss structure, FIG. 3F is a cross sectional view of a portion of an example truss structure in an example manufacturing fixture, and FIG. 3G is a cross sectional view of a node of an example truss structure, in accordance with implementations described herein.

FIG. 4A is a perspective view, FIG. 4B is a side view, FIG. 4C is an isometric view, and FIG. 4D is an axial end view, of an example truss structure, with longitudinal members being positioned at an outer peripheral portion of the example truss structure, in accordance with implementations described herein.

FIGS. 4E-4F are axial end views of example truss structures, with longitudinal members being positioned at an outer peripheral portion of the example truss structures, in accordance with implementations described herein.

FIG. 5 is a flowchart of an example method of joining an example longitudinal member and an example transverse member, in accordance with implementations described herein.

DETAILED DESCRIPTION

A truss structure may include a plurality of load bearing members joined at a plurality of nodes, and arranged so that the assembled plurality of load bearing members act together, as a single load bearing structure. In some implementations, the load bearing members may be arranged, and joined at the plurality of nodes, so that the load bearing members and nodes are positioned in multiple different planes, defining a three dimensional truss structure. In some implementations, a plurality of longitudinal members may provide for bending and axial strength of the truss structure, and a plurality of transverse members may carry shear and torsional forces applied to the truss structure.
A truss structure, in accordance with implementations described herein, may include a plurality of longitudinal members extending along a longitudinal length of the truss structure. A plurality of transverse members may extend between the longitudinal members. The transverse members define one or more tetrahedral shapes. Portions of the transverse members defining these tetrahedral shapes may be respectively joined to the longitudinal members at a plurality of nodes, to form a lattice type truss structure. In some implementations, the plurality of longitudinal members and the plurality of transverse members may be formed by a series of interwoven fibers, for example, carbon fibers, impregnated with epoxy. The interweaving of these fibers, particularly at the nodes, may join the longitudinal members and the transverse members. This interweaving at the nodes may provide for structural integration of the longitudinal members and the transverse members.
An example truss structure 100, in accordance with implementations described herein, is shown in FIGS. 1A-1D. In particular, FIG. 1A is a perspective view of the example truss structure 100, FIG. 1B is a side view of the example truss structure 100, FIG. 1C is an isometric view of the example truss structure 100, and FIG. 1D is an axial end view of the example truss structure 100. The example truss structure 100 shown in FIGS. 1A-1D is illustrated in a substantially horizontal orientation, with a central longitudinal axis A of the example truss structure 100 extending substantially horizontally, simply for purposes of discussion and illustration. However, the principles to be described herein with respect to the truss structure 100 may also be applied to a plurality of other orientations of the truss structure 100.
The example truss structure 100 may include a plurality of longitudinal members 110 extending axially, along a length L of the truss structure 100. The plurality of longitudinal members 110 may define a longitudinal frame portion of the truss structure 100. This longitudinal frame defined by the plurality of longitudinal members 110 may carry an axial load portion of a force exerted on, or a load borne by the truss structure 100. The example truss structure 100 shown in FIGS. 1A-1D includes eight longitudinal members 110. However, in some implementations, the truss structure 100 may include more, or fewer, longitudinal members 110. Numerous factors may affect the number of longitudinal members 110 included in the truss structure 100. These factors may include, for example, a length of the truss structure 100, a load to be carried by the truss structure 100 (including, for example, an amount of torsional loading, an amount of bending loading, an amount of tension/compression loading, and other such loads which may be applied to the truss structure 100), and the like.
The plurality of longitudinal members 110 defining the longitudinal frame portion of the truss structure 100 may be arranged in parallel to each other, and in parallel with the central longitudinal axis A of the truss structure 100. The arrangement of the longitudinal members 110 may be symmetric about any one of a plurality of different central planes extending through the central longitudinal axis A of the truss structure 100. The exemplary central plane B extending through the central longitudinal axis A of the truss structure 100 shown in FIG. 1D is just one example of a central plane extending through the central longitudinal axis A of the truss structure 100. The longitudinal members 110 of the truss structure 100 may be symmetrically arranged about any number of different central planes extending through the central longitudinal axis of the truss structure 100.
The longitudinal members 110 of the truss structure 100 may carry an axial, or compressive, or bending load applied to the truss structure 100. The transverses members 120 may provide reinforcement to the longitudinal members, to provide buckling resistance to the longitudinal members 110. In some situations/arrangements, the transverse members 120 carry a torsional component of the load applied to the truss structure 100.
The example truss structure 100 may include a plurality of transverse members 120. The plurality of transverse members 120 may define a transverse frame portion of the truss structure 100. This transverse frame portion of the truss structure 100 defined by the plurality of transverse members 120 may carry a torsional load portion of a force exerted on, or a load borne by the truss structure 100. The transverse frame may be coupled to, or joined with, or intersect, or be integrally formed with, the longitudinal frame to form the truss structure 100. That is, the transverse members 120 may be coupled to, or joined with, or intersect, or be integrally formed with, the longitudinal members 110 at a respective plurality of nodes 150.
In some implementations, the transverse members 120 may be disposed in a helical arrangement with respect to the longitudinal members 110 defining the longitudinal frame. For ease of discussion and illustration, FIGS. 2A-2H illustrate a sequential addition of exemplary three dimensional polyhedral structures 130 (each formed by a series of transverse members 120 arranged end to end) to an exemplary longitudinal frame including a plurality of longitudinal members 110, to form the truss structure 100, in accordance with implementations described herein. These three dimensional polyhedral structures 130 may be referred to as helical structures 130, simply for ease of discussion, in that the three dimensional polyhedral structures 130 appear to follow a somewhat helical pattern with respect to the longitudinal frame defined by the longitudinal members 110. The helical structures 130 may be incrementally, and sequentially, positioned along the longitudinal frame defined by the longitudinal members 110. In the example shown in FIGS. 2A-2H, the longitudinal frame includes eight longitudinal members 110 arranged in parallel to each other, about a central longitudinal axis A, and arranged symmetrically about a central longitudinal plane B, as described above. Each of FIGS. 2A through 2H includes an axial view (a) of the truss structure 100, and a longitudinal perspective view (b) of the truss structure 100 as a series of helical structures 130 are added to the arrangement of longitudinal members 110. However, as noted above, the truss structure 100 may include more, or fewer, longitudinal members 110, with a configuration of the helical structures 130 formed by the arrangement of transverse members 120 being defined according to the number of longitudinal members 110.
As noted above, FIGS. 2A-2H provide a sequential illustration of the arrangement of exemplary helical structures 130 relative to the exemplary arrangement of longitudinal members 110. This exemplary sequential illustration in FIGS. 2A-2H is provided to facilitate an understanding of the physical arrangement of the transverse members 120 (making up the helical structures 130) relative to the longitudinal members 110. The exemplary sequential illustration shown in FIGS. 2A-2H is not intended to be representative of the process by which the truss structure 100, in accordance with implementations described herein, is actually manufactured.
As shown in FIGS. 2A(a) and 2A(b), a first helical structure 130A may include a plurality of transverse members 120 arranged end to end to define the first helical structure 130A. Each of the transverse members 120 of the first helical structure 130A may be joined with respective longitudinal members 110 of the longitudinal frame at respective nodes 150A. FIGS. 2B(a) and 2B(b) illustrate a second helical structure 130B joined with the longitudinal members 120 of the longitudinal frame at respective nodes 150B. As shown in FIGS. 2B(a) and 2B(b), the second helical structure 130B may include a plurality of transverse members 120 arranged end to end to define the second helical structure 130B. Similarly, FIGS. 2C(a) and 2C(b) illustrate a third helical structure 130C, including a plurality of transverse members 120 arranged end to end, joined with the longitudinal members 120 of the longitudinal frame at respective nodes 150C; FIGS. 2D(a) and 2D(b) illustrate a fourth helical structure 130D, including a plurality of transverse members 120 arranged end to end, joined with the longitudinal members 120 of the longitudinal frame at respective nodes 150D; FIGS. 2E(a) and 2E(b) illustrate a fifth helical structure 130E, including a plurality of transverse members 120 arranged end to end, joined with the longitudinal members 120 of the longitudinal frame at respective nodes 150E; FIGS. 2F(a) and 2F(b) illustrate a sixth helical structure 130F, including a plurality of transverse members 120 arranged end to end, joined with the longitudinal members 120 of the longitudinal frame at respective nodes 150F; FIGS. 2G(a) and 2G(b) illustrates a seventh helical structure 130G, including a plurality of transverse members 120 arranged end to end, joined with the longitudinal members 120 of the longitudinal frame at respective nodes 150G; and FIGS. 2H(a) and 2 H(b) illustrate an eighth helical structure 130H, including a plurality of transverse members 120 arranged end to end, joined with the longitudinal members 120 of the longitudinal frame at respective nodes 150H.
In the example arrangement shown in FIG. 2H, the transverse members 120 are arranged in eight helical structures 130A through 130H, each defining a somewhat square helical section, joined with eight longitudinal members 110 of the longitudinal frame to form the truss structure 100. However, the truss structure 100 may include more, or fewer, longitudinal members 110 and/or more, or fewer, helical structures 130 formed by the transverse members 120. For example, in some implementations, the truss structure 100 may include six longitudinal members 110. In a truss structure 100 including six longitudinal members 110, the helical structures 130 (each including transverse members 120 arranged end to end) may define somewhat triangular helical sections joined with the longitudinal members 110 at the respective nodes 150. In the example arrangement shown in FIG. 2H, the helical structures 130 are in a counter-clockwise arrangement with respect to the longitudinal members 110. However, in some implementations, the helical structures 130 may be in a clockwise arrangement with respect to the longitudinal members 110.
As noted above, the number of longitudinal members 110 and corresponding number of helical structures 130 (each defined by transverse members 120 arranged end to end) of a particular truss structure may vary based on, for example, an amount of load to be borne by the truss structure, a type of load, a distribution of load, a particular application and/or installation and/or environment in which the truss structure is to be used, and other such factors. In some situations, a truss structure including eight longitudinal members 110 may provide increased rigidity when compared to a truss structure including six longitudinal members 110. A mass of the truss structure including eight longitudinal members 110 may be positioned further (radially outward) from the central longitudinal axis A of the truss structure, when compared to the truss structure including six longitudinal members 110, resulting in a comparatively greater moment of inertia for the truss structure including eight longitudinal members 110. In some arrangements, in the truss structure including eight longitudinal members 110, the helical structures 130 maybe positioned further from the central longitudinal axis A than in the truss structure including six longitudinal members 110, providing for a comparatively greater torque carrying capability for the truss structure including eight longitudinal members 110.
In some implementations, a truss structure including eight longitudinal members 110 positioned at the outer peripheral portion of the truss structure may exhibit as much as 70% greater stiffness, or rigidity, than a comparably sized truss structure including six longitudinal members 110. In some implementations, a truss structure including eight longitudinal members 110 may exhibit as much as 40% to 50% greater torque capacity than a comparably sized truss structure including six longitudinal members 110.
In some implementations, the longitudinal members 110 and the transverse members 120 are joined at a straight portion of the transverse member 120. For example, in some implementations, the nodes 150 (at which the longitudinal members 110 and the transverse members 120 are joined) may occur at a straight portion of the helical structure 130 (i.e., a straight portion of the corresponding transverse member 120), where the helical structure 130 does not change direction, rather than at a portion of the helical structure 130 at which one transverse member 120 is joined to the next adjacent transverse member 120 and the contour of the helical structure 130 changes direction. Connection of the transverse members 120 and the longitudinal members 110 at respective straight portions of the transverse members 120 may enhance the reinforcement of the buckling strength, or buckling resistance, of the longitudinal members 110, and thus enhance the overall strength, and buckling resistance, of the overall truss structure 100. Buckling strength of the truss structure 100 may also be affected by a distance between nodes 150 along a longitudinal member 110. That is, buckling strength, or buckling resistance, of the longitudinal member 110, and of the overall truss structure 100, may be further enhanced, or increased, as a distance d (see FIG. 1B) between adjacent nodes 150 along the longitudinal member 110 is decreased.
In some implementations, a material from which the longitudinal members 110 and/or the transverse members are made may be selected, taking into account various different characteristics of the material (such as, for example, strength, weight, cost, availability and the like), together with required characteristics of the truss structure 100 (such as, for example, size, load bearing capability and the like). For example, in some implementations, the longitudinal members 110 and/or the transverse members 120 may be made of a carbon type material, a glass type material, a basalt type material, a kevlar type material, and other such materials.
The truss structure 100 including longitudinal members 110 and/or transverse members 120 made of, for example, a carbon fiber material may be relatively light in weight relative to, for example, a comparable support structure made of, for example, a metal material such as steel, while being capable of bearing the same (or a greater) load than the comparable support structure made of a metal material. In another comparison, the truss structure 100 including longitudinal members 110 and/or transverse members 120 made of this type of carbon fiber material may be considerably stronger than, for example, a comparable support structure made of, for example, a metal material, of essentially the same weight and/or size. For example, in some implementations, the truss structure 100 including longitudinal members 110 and/or transverse members 120, structured in the manner described herein, and made of this type of carbon fiber material, may be approximately ten times stronger, than a steel tube of essentially the same weight.
A truss structure 100, in accordance with implementations described herein, may garner a considerable increase in strength from the material used for the longitudinal members 110 and/or the transverse member 120, in combination with the geometric structure defined by the arrangement of the longitudinal members 110 and the transverse members 120, and/or the geometric structure of the longitudinal members 110 and/or the transverse members 120 themselves.
In some implementations, a cross sectional shape of one or more of the longitudinal members 110 may be substantially triangular. In some implementations, a cross section of one or more of the longitudinal members 110 may be defined by another shape. For example, in some implementations, the cross sectional shape of one or more of the longitudinal members 100 may be circular, elliptical, square, rectangular, trapezoidal, and the like. In some implementations, all of the longitudinal members 100 may have substantially the same cross sectional shape. In some implementations, a cross sectional shape of one or more of the transverse members 120 may be substantially triangular. In some implementations, a cross section of one or more of the transverse members 120 may be defined by another shape. For example, in some implementations, the cross sectional shape of the one or more of the transverse members 120 may be circular, elliptical, square, rectangular, trapezoidal, and the like. In some implementations, all of the transverse members 120 may have substantially the same cross sectional shape. In some implementations, the cross sectional shape of one or more of the longitudinal members 110 may be substantially the same as the cross sectional shape as one or more of the transverse members 120. In some implementations, the longitudinal members 110 and the transverse members 120 may have different cross sectional shapes.
Hereinafter, an exemplary truss structure 200 will be described in which the longitudinal members 110 have a triangular cross sectional shape. In some implementations, the transverse members 120 of this exemplary truss structure 200 may also have a triangular cross sectional shape.
Various views of the example truss structure 200, including longitudinal members 110 having a substantially triangular cross sectional shape, are shown in FIGS. 3A-3D. FIGS. 3E and 3F provide a perspective view and an axial end view, respectively, of an example of a single longitudinal member 110 having a substantially rectangular cross section, and FIG. 3G is a cross sectional view of an example node 150 at which a longitudinal member 1120 and a transverse member 120 (of a corresponding helical structure 130) are joined. The example truss structure 200 shown in FIGS. 3A-3D includes eight longitudinal members 110, with transverse members 120 arranged end to end in helical structures 130 defining square helical sections. However, the truss structure 200 may include more, or fewer, longitudinal members 110, with the configuration of the transverse members 120 forming the helical structures 130 being adjusted accordingly.
As shown in FIGS. 3A-3E, the longitudinal members 110 having the triangular cross section may join, or intersect with, or be integrally formed with, the transverse members 120 forming the helical structures 130 at a respective plurality of nodes 150. In some implementations, the longitudinal members 110 and the transverse members 120 may be integrally joined at the nodes 150. For example, in some implementations, the longitudinal members 110 and the transverse members 120 may be made of a carbon fiber material. The carbon fiber material of the longitudinal members 110 and the transverse members 120 may include, for example, a plurality of strands that woven together to form a node 150 that integrally couples, or joins, the corresponding longitudinal member 110 and transverse member 120. For example, strands of the longitudinal member(s) 110 may be alternately arranged with the strands of the transverse member(s) 120 at the nodes 150, thus interweaving the longitudinal members 110 and the transverse members 120 at the nodes 150, and creating a substantially integral truss structure 200 from the longitudinal members 110 and the transverse members 120. In some implementations, this arrangement of the strands of the material of the longitudinal member 110 and the strands of the material of the transverse member 120 may be guided by features of a manufacturing fixture.
For example, in some implementations, the strands of the material of the longitudinal member(s) 110 and the strands of the material of the transverse members 120 may be laid up, or woven, on a manufacturing fixture 300 including grooves 320, or pockets, at points defining the nodes 150, as shown in FIG. 3F. The strands of the longitudinal member(s) 110 and the strands of the transverse member(s) 120 may be alternately arranged in these grooves in the fixture, to achieve the interweaving of the strands of the longitudinal member(s) 110 and the strands of the transverse member(s) 120, and the resulting integral structure of the truss structure 200.
An example of a method 500 of joining the longitudinal member(s) 110 and the transverse member(s) 120, or forming node(s) 150 at the intersection of the longitudinal member(s) 110 and the transverse member(s) 120 by, for example, a lay-up and/or interweaving of strands or fibers of materials of the longitudinal member(s) 110 and transverse member(s) 120, is shown in FIG. 5. In some implementations, the method 500 may include an alternating layering of the strands or fibers of a first member (for example, one of the longitudinal member 110 or the transverse member 120) with a second member (for example, the other of the longitudinal member 110 or the transverse member) in, for example, a recess or groove of a fixture.
For example, in some implementations, the method 500 may include forming a first section of the node 150 (block 510). In some implementations, the first section of the node 150 may include an interweaving of strands or fibers from the material of the first member with strands or fibers from the material of the second member. For example, the first section may include an interweaving of (a portion of) strands from the first member with (a portion of) strands from the second member. In some implementations, a second section of the node 150 may be formed adjacent to the first section of the node 150 (block 520). In some implementations, the second section may include a laying-in of (a portion of) the strands of the second member (either alone, or together with a portion of the strands of the first member) adjacent to the first section. In some implementations, a third section of the node 150 may be formed adjacent to the second section of the node 150 (block 530). In some implementations, the third section may include an interweaving of a (remaining) portion of the strands of the first member with a (remaining) portion of the strands of the second member. The layering of adjacent sections of the node 150 may include more, or fewer sections than discussed in this example, and/or different combinations of interwoven strands of the first and second members, and/or different sequencing of the strands of the first and second members. The layering of adjacent sections of the node 150 with strands of material from the first member and the second member may continue until it is determined that all of the strands of material have been incorporated into the node 150 (block 540). In some implementations, the layers or sections of material received in the recess or groove in this manner may be compressed in the recess or groove, to, for example, facilitate the reduction and/or elimination of voids. In some implementations, for example, when the material of the first member and/or the second member is pre-impregnated with an epoxy/resin material, the material received in the recess or groove in this manner may then be processed, for example, cured, to join the first member and the second member in an interwoven, or integral manner (block 550).
An example node 150, joining a longitudinal member 110 and a transverse member 120 (of one of the helical structures 130 of the truss structure 200), is shown in FIG. 3G. The example node 150 may include a first section 150A, which is formed by an interweaving of strands of material of the longitudinal member 110 and strands of material of the transverse member 120. The first section 150 of the example node 150, is illustrated by FIG. 3G by cross-hatching, to represent the interweaving of the respective strands. Various different patterns, or alternating arrangements, of strands may be implemented to accomplish this interweaving. The example node 150 may also include a second section 150B, positioned adjacent to the first section 150. In the example node 150 shown in FIG. 3G, the second section 150B of the node 150 has not yet been formed. The second section 150B may be made of the remaining strands of the material of the longitudinal member 110 and the remaining strands of material of the transverse member 120. The pattern, or arrangement of the respective strands in the second section 150B of the node 150 may be different from that of the first section 150A, or may be the same as that of the first section 150A. In some implementations, the second section 150B of the node 150 may include multiple sub-sections or layers, having multiple different arrangements of strands of the materials of the longitudinal member 110 and the transverse member 120.
In a first, non-limiting example of this type of alternating lay up of the fibers, or strands, of the longitudinal members 110 and the transverse members 120 in the groove defining the node 150 may include a weaving of approximately 25% of the strands of the longitudinal member 110 with approximately 50% of the stands of the transverse member 120, followed by approximately 50% of the strands of the longitudinal member 110, and then followed by a weaving of the remaining approximately 25% of the strands of the longitudinal member 110 with the remaining approximately 50% of the strands of the transverse member 120. This is just one example of an alternating layup of the strands of the longitudinal members 110 and the transverse members 120 in the groove defining the node 150. Other combinations of alternating carbon fiber material within the grooves of the fixture defining the nodes 150 may also be used, based on, for example, a size and/or shape and/or configuration of the truss structure 200, a type of material used for the longitudinal members 110 and/or the transverse members 120, a load to be carried by the truss structure 200, a geometric configuration of the helical structures 130, a cross sectional shape of the transverse members 120, and other such factors.
For example, in a second, non-limiting example of this type of alternating lay up of the fibers, or strands, of the longitudinal members 110 and the transverse members 120 in the groove defining the node 150 may include a relatively straightforward, consistent, repeated alternating layup, or weaving, of the strands of the longitudinal member 110 and the strands of the transverse member 120 at the node 150. This could include, for example, a layup at the node of a strand from the longitudinal member 110 followed by a strand from the transverse member 120, and then another strand from the longitudinal member 110 followed by another strand from the transverse member 120, repeating this pattern until all of the strands of the longitudinal member 110 and all of the strands of the transverse member 120 have been incorporated at the node 150. This example pattern is not necessarily limited to a repeated alternating pattern of a single strand from the longitudinal member 110, followed by a single strand from the transverse member 120. Rather, this example pattern could include a repeated alternating pattern of multiple strands from the longitudinal member 110 followed by (the same number of) multiple strands from the transverse member 120.
The first and second examples presented above may be applied in an arrangement in which, for example, a number of tows, or strands, in the helical structures 130 formed by the transverse members 120 would be half that of the longitudinal members 110. For example, the example (completed) truss structure illustrated in FIGS. 2A-2H includes eight longitudinal members 110, and sixteen helical structures 130 formed by the transverse members 120. If each of the helical structures 130 includes half the number of tows, or strands, of the longitudinal members 120, the first and second examples presented above may produce nodes 150 which incorporate all of the strands from the longitudinal members 110 and the transverse members 120 at each node 150. However, in some implementations, a third non-limiting example may include a pattern in which a ratio of longitudinal members 110 to helical structures 130 is not necessarily two to one. For example, in a truss structure which includes a three to one ratio of longitudinal members 110 to helical structures 130, a lay up pattern at the node 150 may include, for example, two strands from the helical structures 130 (one from each direction), followed by three strands from the longitudinal member 110, followed by another two strands from the helical structure 130, followed by another three strands from the longitudinal member 110, until all of the strands from the longitudinal member 110 and the helical structure 130 are incorporated at the node 150.
As noted above, these are just some examples of alternating layups of the strands of the longitudinal members 110 and the transverse members 120 forming the helical structures 130 in the groove defining the node 150. Other combinations of alternating carbon fiber material within the grooves of the fixture defining the nodes 150 may also be used, based on, for example, a size and/or shape and/or configuration of the truss structure, a type of material used for the longitudinal members 110 and/or the transverse members 120 forming the helical structures 130, a load to be carried by the truss structure, a geometric configuration of the helical structures 130, a cross sectional shape of the transverse members 120, and other such factors.
In some implementations, grooves 320 (for example, a series of grooves 320) in the manufacturing fixture 300 defining the longitudinal member(s) 110 and/or the transverse member(s) 120 and/or the nodes 150 at which the longitudinal member(s) 110 and the transverse member(s) 120 intersect, may have a V shape, as shown in the example illustrated in FIG. 3F. Layup of the fibers, or strands, of the carbon fiber material of the longitudinal member(s) 110 and the transverse member(s) 120 in the V groove 320, for example, in the manner described above, may facilitate layup of the carbon fiber material in the V groove 320, may enhance compaction, or consolidation, of the material in the V groove 320, and may produce the substantially triangular cross section shown in FIGS. 3E and 3F. In some implementations, the carbon fiber material may be pre-impregnated (pre-preg) with an epoxy resin material. Interwoven layup of the strands of pre-preg carbon fiber material in the V grooves 320 in the manner described above, having enhanced compaction in the V groove 320, followed by curing of the pre-preg carbon fiber material, may produce longitudinal member(s) 110 and/or transverse member(s) 120 and/or nodes 150 having a relatively low void ratio along the length of the truss structure 200 (i.e., the longitudinal members 110 and the transverse members 120 of the truss structure 200).
Longitudinal members 110 having a triangular cross sectional shape as described above may be produced using less material than longitudinal members 200 having other cross sectional shapes (for example, circular or rectangular/square cross sectional shapes), while providing at least equal, and in most circumstances, greater load bearing capability. The unexpected increase in load bearing capability provided by the longitudinal members 110 having the triangular cross section described above, when compared to truss structures with longitudinal members having other cross sectional shapes, is illustrated in Table 1 below. In particular, in one example, a truss structure with longitudinal members having a square cross section exhibited approximately 4.7% more load bearing capability than a comparable truss structure with longitudinal members having a circular cross section. In one example, a truss structure with longitudinal members having a triangular cross section exhibited approximately 20.9% more load bearing capability than comparable a truss structure with longitudinal members having a circular cross section. This significant, and unexpected, magnitude of improvement exhibited by the truss structure 200 with longitudinal members 110 having a triangular cross section may be due to improved local buckling resistance (buckling between two adjacent nodes 150 along a longitudinal member 110) and increased moment of inertia.
As noted above, one mode of failure of a truss structure 100 in accordance with implementations described herein may include buckling of individual longitudinal members 110. The ability of an individual longitudinal member 110 to resist bending and/or buckling may be directly proportional to an area moment of inertia of the longitudinal member 110. That is, by increasing moment of inertia, stiffness may be increased, thus reducing deflection of the truss structure under a given load. Table 1 below illustrates the difference in area moment of inertia for three different exemplary longitudinal members 110, each having a different cross sectional shape (i.e., circular, triangular, and square), holding an amount of material, of the cross sectional area, of the longitudinal members 110 constant for the three examples. As shown in Table 1, a longitudinal member having a triangular cross section may exhibit an increase in area moment of inertia of approximately 20.9% (compared to a longitudinal member 110 having a circular cross section of the same cross sectional area), affording the longitudinal member 110 having the triangular cross section an approximately 20.9% improvement in buckling strength over the longitudinal member 110 having the circular cross section. Similarly, a longitudinal member having a square cross sectional shape may exhibit an approximately 4.7% improvement in buckling resistance over a longitudinal member 110 having a circular cross section.

TABLE 1

Circular	Triangular	Square

Cross sectional area	1	1	1
(in{circumflex over ( )}2)
Moment of Inertia	0.07957747155	0.09621333333	0.08333333333
(in{circumflex over ( )}4)
% difference in	0	20.90524047	4.71975512
moment of inertia
related to circular

In the example truss structure 200 described above, the longitudinal members 110 have a triangular cross sectional shape. In some implementations, all of the longitudinal members 200 have a triangular cross sectional shape. In some implementations, some, or all, of the transverse members 120 defining the helical structures 130 have a triangular cross sectional shape. In some implementations, some, or all, of the transverse members 120 defining the helical structures 130 have a cross sectional shape that is different than the triangular cross sectional shape of the longitudinal members 110.
Hereinafter, a truss structure 400, in accordance with implementations described herein, may include a plurality of longitudinal members 110 positioned along an outer peripheral portion of the truss structure 400, will be described with reference to FIGS. 4A-4F. Positioning of the longitudinal members 110 along the outer peripheral portion of the truss structure 400 may enhance load bearing strength of the truss structure 400 (by, for example, increasing buckling strength/resistance), and may increase moment of inertia of the truss structure 400. In particular, by positioning the longitudinal members 110 at an outer peripheral portion of the truss structure 400 (rather than, for example, an interior facing side portion of the helical structures 130), moment of inertia for the truss structure 400 may be increased. This may allow the truss structure 400 shown in FIGS. 4A-4F to carry a greater load (when compared to, for example, an interior side positioning of the longitudinal members 110 relative to the transverse members 120 of the helical structures 130), or to carry essentially the same load while utilizing less material in the manufacture of the truss structure 400. In some situations, or some arrangements of the longitudinal members 110, positioning of the longitudinal members 110 at the outer peripheral portion of the truss structure 400 in this manner may increase the moment of inertia of the truss structure 400 by as much as approximately 70%.
In the example truss structure 400 shown in FIGS. 4A-4D, the longitudinal members 110 are positioned at an outer peripheral portion of the truss structure 400, and have a circular cross sectional shape. In the example truss structure 400 shown in FIG. 4E, the longitudinal members 110 are positioned at an outer peripheral portion of the truss structure 400, and have a triangular cross sectional shape. In the example truss structure 400 shown in FIG. 4F, the longitudinal members 110 are positioned at an outer peripheral portion of the truss structure 400, and have a rectangular cross sectional shape. As noted above, the longitudinal members 110 may have other cross sectional shapes.
Regardless of the cross sectional shape of the longitudinal members 110, positioning of the longitudinal members 110 at the outer peripheral portion of the truss structure 400 may increase overall strength (for example, buckling resistance) of the truss structure 400, and may increase moment of inertia of the truss structure 400. Overall strength of the truss structure 400 may be further enhanced based on a type of material used for the longitudinal members 110 and/or the transverse members 120, as described in detail above. Overall strength of the truss structure 400 may be further enhanced by the improved compaction, and improved void ratio, afforded by the triangular cross sectional shape as described above. Increased strength of the truss structure 400 may enhance utility of the truss structure 400, provide for use of the truss structure 400 in a variety of different environments, and expand on applications for use of the truss structure 400.
In the foregoing disclosure, it will be understood that when an element, such as a layer, a region, or a substrate, is referred to as being on, connected to, or coupled to another element, it may be directly on, connected or coupled to the other element, or one or more intervening elements may be present. In contrast, when an element is referred to as being directly on, directly connected to or directly coupled to another element or layer, there are no intervening elements or layers present. Although the terms directly on, directly connected to, or directly coupled to may not be used throughout the detailed description, elements that are shown as being directly on, directly connected or directly coupled can be referred to as such. The claims of the application may be amended to recite exemplary relationships described in the specification or shown in the figures.
As used in this specification, a singular form may, unless definitely indicating a particular case in terms of the context, include a plural form. Spatially relative terms (e.g., over, above, upper, under, beneath, below, lower, and so forth) are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. In some implementation, the relative terms above and below can, respectively, include vertically above and vertically below. In some implementations, the term adjacent can include laterally adjacent to or horizontally adjacent to.
While certain features of the described implementations have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the scope of the implementations. It should be understood that they have been presented by way of example only, not limitation, and various changes in form and details may be made. Any portion of the apparatus and/or methods described herein may be combined in any combination, except mutually exclusive combinations. The implementations described herein can include various combinations and/or sub-combinations of the functions, components and/or features of the different implementations described.

Claims

1. A three-dimensional (3D) load bearing structure, comprising:

a longitudinal frame including a plurality of longitudinal members arranged in parallel with respect to a central longitudinal axis of the load bearing structure and extending longitudinally along a length of the transverse frame; and

a transverse frame integrally coupled with the longitudinal frame at a respective plurality of nodes, the transverse frame including a plurality of transverse members defining a plurality of 3D polyhedral structures sequentially arranged along the central longitudinal axis of the load bearing structure, each of the 3D polyhedral structures following a helical pattern relative to the central longitudinal axis;

wherein:

the plurality of nodes are respectively defined at a plurality of points of intersection between the plurality of longitudinal members and the plurality of 3D polyhedral structures; and

each of the plurality of nodes includes an interweaving of longitudinal fibers of a longitudinal membr, of the plurality of longitudinal members, with transverse fibers of a transvers member of a polyhedral structure, of the plurality of 3D polyhedral structures.

2. The structure of claim 1, wherein the longitudinal frame is integrally coupled to the transverse frame at points at which a contour of each of the plurality of 3D polyhedral structures changes direction.

3. The structure of claim 1, wherein the transverse frame is integrally coupled to the longitudinal frame at points at which a contour of each of the plurality of 3D polyhedral structures forms an apex.

4. The structure of claim 3, wherein each apex of each of the plurality of 3D polyhedral structures is integrally coupled to a corresponding longitudinal member of the plurality of longitudinal members.

5. The structure of claim 1, wherein the longitudinal frame includes six longitudinal members, each extending in parallel to the central longitudinal axis of the load bearing structure.

6. The structure of claim 1, wherein a fiber pattern at each of plurality of nodes includes:

a first section including an interweaving of a first portion of the transverse fibers of the respective polyhedral structure and a first portion of the longitudinal fibers of the respective longitudinal member;

a second section adjacent to the first section, the second section including an arrangement of a second portion of the longitudinal fibers of the respective longitudinal member; and

a third section adjacent to the second section, the third section including an interweaving of a second portion of the transverse fibers of the respective polyhedral structure and a third portion of the longitudinal fibers of the respective longitudinal member.

7. A method of forming a load bearing structure, comprising:

integrally forming a transverse frame and a longitudinal frame, the transverse frame including a plurality of transverse members arranged end to end to define a plurality of three-dimensional (3D) polyhedral structures, and the longitudinal frame including a plurality of longitudinal members arranged in parallel with respect to a central longitudinal axis of the load bearing structure, wherein integrally forming the transverse frame and the longitudinal frame includes:

forming a plurality of nodes at a respective plurality of points of intersection between the transverse frame and the longitudinal frame, including, for each nodc of the plurality of nodes:

interweaving transverse fibers of a transverse member of a corresponding 3D polyhedral structure with longitudinal fibers of a longitudinal member of the plurality of longitudinal members, at a portion of the transverse frame at which a contour of each of the plurality of 3D polyhedral structures forms an apex.

8. The method of claim 7, wherein integrally forming the transverse frame and the longitudinal frame includes integrally forming the transverse frame and the longitudinal frame including six longitudinal members arranged in parallel to the central longitudinal axis of the load bearing structure, and arranged symmetrically about a central longitudinal plane of the load bearing structure.

9. The method of claim 8, wherein each of the plurality of 3D polyhedral structures includes a plurality of apexes, and wherein each apex of the plurality of apexes of each of the plurality of 3D polyhedral structures is positioned at a respective node of the plurality of nodes.

10. The method of claim 7, wherein interweaving the transverse fibers of the transverse member of the corresponding 3D polyhedral structure with the longitudinal fibers of the longitudinal member of the plurality of longitudinal members includes:

forming a first section of the node, including arranging the longitudinal fibers of the longitudinal member and the transverse fibers of the transverse member in a first pattern; and

forming a second section of the node, the second section being adjacent to the first section, including arranging remaining longitudinal fibers of the longitudinal member and remaining transverse fibers of the transverse member in a second pattern,

wherein the second pattern is different from the first pattern.

11. The method of claim 10, further comprising:

compressing the first section and the second section of the node; and

curing the compressed first section and second to form the node integrally coupling the longitudinal member and the transverse member

12. The method of claim 10, wherein forming the second section of the node includes:

forming a first portion of the second section of the node, the first portion of the second section being adjacent to the first section of the node; and

forming a second portion of the second section, the second portion of the second section being adjacent to the first portion of the second section.

13. The method of claim 12, wherein

forming the first portion of the second section of the node includes arranging a first portion of the remaining longitudinal fibers of the longitudinal member and a first portion of the remaining transverse fibers of the transverse member in a third pattern; and

forming the second portion of the second section of the node includes arranging a second portion of the remaining longitudinal fibers of the longitudinal member and a second portion of the remaining transverse fibers of the transverse member in a fourth pattern.

14. The method of claim 12, wherein the first portion of the second section of the node includes only longitudinal fibers of the longitudinal member, and the second portion of the second section of the node includes the remaining longitudinal fibers of the longitudinal member and the remaining transverse fibers of the transverse member.