A truss structure

Abstract

The present invention relates to lattice materials (5) used in many engineering fields, particularly materials engineering. These materials are formed from a lattice structure (1) comprising an inner element (2) in the form of an irregular polygon having at least six edges, with struts arranged along each edge to create at least one triangle (3.1).

Description

[0001] A TRUSS STRUCTURE

[0002] Field of the Invention

[0003] The present invention relates to lattice materials, which are used in many engineering fields, particularly materials engineering, consisting of a lattice structure obtained by arranging struts on each edge of an irregular polygon (at least with six edges) to form at least one triangle.

[0004] Prior Art

[0005] This application is an additional patent that is a continuation of the patent application numbered TR 2021 / 016251. In this application, an inner element that is different from the inner element defined in the patent application numbered TR 2021 / 016251 is defined and different embodiments of the said inner element are defined.

[0006] In the state of the art, there is no description of the technical features included in the present invention subject to the application and the technical effects provided by the invention subject to the application. In prior art applications, lattice materials consisting of a lattice structure whose unit cells are obtained by arranging struts to form at least two triangles on each edge of a polygon (triangle, quadrilateral, or hexagonal) are not encountered.

[0007] Most readily available negative Poisson’s ratio (NPO) lattice materials exhibit anisotropic mechanical properties and low stiffness. Therefore, increasing the stiffness of existing NPO lattice materials using various techniques or designing new lattice materials with isotropic mechanical properties and high stiffness is an active area of research. In addition, since lattices are multifunctional materials, the concept of "better" properties varies between applications. In some applications, high stiffness is favored, whereas, in others, Poisson’s ratio or thermal properties may take precedence. Each newly designed lattice structure (i.e., one with a particular microarchitecture) possesses unique physical and mechanical properties and offers advantages in several application areas. The in-plane elastic mechanical properties of “Hierarchical Triangular" and "Mixed Hexagonal -Triangular" lattice families formed from the truss structure provided by the present invention are isotropic when all its struts are made from the same isotropic material, whereas the in-plane elastic mechanical properties of "Mixed Quadrilateral-Triangular" lattice family are orthotropic. Due to their superior properties, the members of the lattice families formed from the truss structure described in the present invention can be used in various engineering applications, mainly as multifunctional materials.

[0008] Objects of the Invention

[0009] The objective of the present invention is to develop lattice materials consisting of a lattice structure obtained from an irregular polygon having at least six edges.

[0010] A further objective of the present invention is to realize lattice materials consisting of a lattice structure obtained from an irregular polygon whose inner element has six (6) edges, eight (8) edges, nine (9) edges, twelve (12) edges, fifteen (15) edges, sixteen (16) edges, eighteen (18) edges. The number of inner element edges of an irregular polygon is at least six and can be increased to a multiple of three or four.

[0011] A further objective of the present invention is to develop lattice materials comprising a truss structure formed by arranging struts to create a triangle on each edge of the inner element. A further objective of the present invention is to produce novel lattice materials with enhanced mechanical properties and high elastic and shear moduli.

[0012] Brief Description of the Invention

[0013] A truss structure, as defined in the first claim and the other claims dependent on this claim, implemented to achieve the objective of the present invention, consists of an inner truss element and outer struts. The truss structure of the present invention is obtained by placing outer struts on the inner element edges of the inner element of the truss. Combining truss structures yields unit cells, and lattice materials used in numerous engineering applications are generated by tessellating the plane with the unit cells.

[0014] In the invention that is the subject of this application, the inner element of the truss structure is an irregular polygon and the irregular polygon has at least six edges. The number of inner element edges can be 8, 9, 12, 15, 16, 18 and 24 (or more) edges, in addition to six. There is a triangle obtained from the outer struts on each edge of the inner element. There is an angle between the triangles, and by changing this angle, the triangles can be brought closer or further apart. Different lattice structures can be obtained by changing the angle between the triangles. The angle between triangles can be obtuse, acute or right angles. The angle between the triangles can be changed until the triangle edges touch each other. The angle between the triangles can be between 0°-180°; however, since the triangle edges will touch each other, it cannot be equal to 0 or 180 degrees. By changing the angle between the triangles, different lattice structures and therefore lattice structures with different properties can be obtained. With each angle change, materials with different mechanical properties can be obtained.

[0015] The truss structure described in the present application comprises an inner element having at least six edges. The inner element of the truss structure is formed by combining the inner element edges. The inner element of the truss structure is formed as an irregular polygon with at least six edges, and the number of edges can be increased to multiples of three greater than six (nine, twelve, fifteen, eighteen, twenty-one, twenty-four, twenty-seven, and more) or multiples of four greater than six (eight, twelve, sixteen, twenty, twenty-four, twenty-eight, and more). In the inner element of the truss structure in the invention that is the subject of the present application, outer struts are placed on the edges of the inner element. The outer struts are placed by joining them to form at least one triangle on the edge of the inner element. There is a preferred angle between the triangles on each edge of the inner element. The angle between the triangles can also preferably be the same as the angle between the acute angled edges of the inner element. In a different embodiment of the invention, the angle between the triangles and the acute angle between the inner element edges may also be different. Lattice materials with different mechanical properties can be obtained by varying the values of these angles.

[0016] The truss structures in the invention are combined to obtain a unit cell and the unit cells are combined to obtain a lattice structure. By adding unit cells to each other, lattice materials with superior in-plane isotropic or orthotropic mechanical properties and negative Poisson's ratio (NPO) can be obtained. The two- dimensional (2D) lattice material created can be folded on any axis on the plane to obtain a cylindrical tube. It is also possible to produce spherical lattice structures from lattice materials comprising the truss structure of the invention disclosed in the present application. By changing the angle between the triangles formed by the outer struts in the truss structure in the invention in question, in other words by rotating the triangles, the elastic modulus, shear modulus and Poisson's ratio of the resulting lattice material change. In the truss structure of the invention disclosed herein, optional auxiliary struts can be incorporated into the inner element. The auxiliary struts serve to tailor the mechanical properties of the lattice material derived from the truss structure as required.

[0017] Detailed Description of the Invention The truss structure realized to achieve the objectives of the present invention are depicted in the following figures:

[0018] Figure 1. A truss structure with an irregular polygon as its inner element.

[0019] Figure 2. View of a unit cell obtained by combining six truss structures.

[0020] Figure 3. View of a two-dimensional lattice structure obtained by the combination of unit cells.

[0021] Figure 4. View of a truss structure with irregular polygon inner elements and auxiliary struts.

[0022] Figure 5. View of a unit cell obtained by combining six truss structures with auxiliary struts.

[0023] Figure 6. View of a two-dimensional lattice structure obtained by combining unit cells with auxiliary struts.

[0024] Figure 7. View of a truss structure with an irregular dodecagonal polygon as its inner element, with auxiliary struts.

[0025] Figure 8. View of a two-dimensional lattice structure obtained by combining unit cells with auxiliary struts.

[0026] The parts in the figures are enumerated individually, and the corresponding descriptions for each number are given below.

[0027] 1. Truss structure

[0028] 2. Truss structure’s inner element

[0029] 2.1. Inner element edge

[0030] 3. Outer strut

[0031] 3.1. Triangle

[0032] 4. Unit cell

[0033] 5. Two-dimensional (2D) lattice structure

[0034] 6. Auxiliary strut In its most basic form, a truss structure (1), which forms the basis of lattice materials obtained by tessellating unit cells in the plane and ensures that the elastic modulus values per unit weight of the formed lattice materials are greater than those of many existing cellular solids with stochastic distribution and many existing lattice materials, consists of: at least one truss structure’s inner element (2) in irregular polygonal geometric form, formed by combining inner element edges (2.1) containing at least six inner element edges (2.1), outer strut (3) placed on the inner element edges (2.1) of the truss structure’s inner element (2), and placed by combining to form a triangle (3.1) on each inner element edge (2.1),

[0035] - triangle (3.1) structure on each inner element edge (2.1) and

[0036] - triangles (3.1) each positioned at an angle to the other triangle (3.1) on the other inner element edge (2.1)

[0037] Truss structure (1) consists of the truss structure’s inner element (2) and the triangles (3.1) located on the inner element edges (2.1). There is a triangle (3.1) on each inner element edge (2.1) of the truss structure’s inner element (2). The triangle (3.1) is obtained by combining the outer struts (3) on the inner element edge (2.1) to form a triangular geometric form.

[0038] The unit cell (4) is obtained by combining the truss structures (1). In one embodiment of the invention, the truss structure’s inner element (2) is an irregular polygon having six inner element edges (2.1) In this embodiment, the unit cell (4) is produced by combining six such inner elements (2).

[0039] A two-dimensional (2D) lattice structure (5) of the desired size can be obtained by combining the required number of unit cells (4).

[0040] The truss structure (1) may optionally contain auxiliary struts (6) that can be placed in different regions, in different numbers, and in different directions within the truss structure's inner element (2), increasing the resistance of the truss structure (1) to deformation.

[0041] In one embodiment of the present invention, the two-dimensional (2D) lattice structure (5) obtained by joining the unit cells (4) to each other can be folded around an axis in the plane to obtain lattice structures in the form of a first cylindrical tube or a second cylindrical tube.

[0042] The truss structure (1) at issue in this application is utilized in numerous engineering fields, especially in materials engineering. The truss structure (1) at issue in this application consists of the truss structure’s inner element (2) and the outer struts (3). The truss structure (1) of the present invention is formed by placing outer struts (3) so as to create at least one triangle (3.1) on each edge (2.1) of the truss structure’s inner element (2), which can have the form of a hexagon or an irregular polygon with a number of edges that are multiples of three greater than six (such as nine, twelve, fifteen, eighteen, twenty-one, twenty-four, twentyseven, or more), or multiples of four greater than six (such as eight, twelve, sixteen, twenty, twenty -four, twenty-eight, or more). The truss structures (1) are combined to create the unit cell (4).

[0043] Two-dimensional (2D) lattice materials (5) are obtained by tessellating unit cells (4) across a plane. In other words, the truss structures (1) constitute the unit cells (4), and the unit cells together form the lattice materials. The truss structure (1) enables the resulting lattice materials to achieve elastic modulus values per unit weight that are higher than those of many existing cellular solids with stochastic distribution and many other known lattice materials.

[0044] Depending on the geometric form of the truss structure’s inner element (2) and the angle between the triangles (3.1) placed on the inner element edges (2.1), it is possible to produce lattice materials with in-plane isotropic mechanical properties and high elastic and shear moduli. Depending on the geometric form of the truss structure’s inner element (2) and the angle between the triangles (3.1) placed on the inner element edges (2.1), it is possible to produce lattice materials with different negative Poisson’s ratio (NPO) values.

[0045] The truss structure (1) at issue in this application may optionally include auxiliary struts (6). Auxiliary struts (6) help to adjust the mechanical properties of the truss structure (1) in a desired way. The lattice structure (5) formed from the truss structure (1) can be folded around an axis in the plane to obtain lattice structures in the form of a first cylindrical tube or a second cylindrical tube. Spherical lattice structures can be created by joining truss structures (1).

[0046] Two-dimensional (2D) lattice structure (5) included in one embodiment of the present invention is obtained by tessellating the unit cells (4) in the plane. By combining the truss structures (1), unit cells (4) are obtained, and by tessellating the unit cells (4) in the plane, a two-dimensional (2D) lattice structure (5) is obtained.

[0047] The auxiliary strut (6), in one embodiment of the invention, can optionally be placed inside the truss structure (1). The auxiliary strut (6) allows the mechanical properties of the truss structure (1) in which it is placed to be adjusted as desired.

[0048] In one embodiment of the invention, cylindrical lattice structures in the form of a first cylindrical tube or a second cylindrical tube are obtained by folding the two- dimensional (2D) lattice structure (5), which is formed by combining the unit cells (4), around an axis in the plane. Spherical lattice structures can also be created by joining truss structures (1).

[0049] Truss structure’s inner element (1) is obtained by combining the inner element edges (2.1) of equal length. In a different alternative embodiment of the invention, the inner element (2) can be obtained by combining inner element edges (2.1) of different lengths or by combining some inner element edges (2.1) of equal length and some inner element edges (2.1) of different lengths.

[0050] Outer struts (3) are preferably added to each inner element edge (2.1) of the truss structure’s inner element (2) to form a triangle (3.1). Preferably, there is a triangle (3.1) on each inner element edge (2.1) of the truss structure’s inner element (2). The edge of the triangle (3.1) that coincides with the inner element edge (2.1) can be considered as the base edge. The junction point where the other edges, extending from the base edge, meet is the vertex of the triangle (3.1). The triangles on the edges (2.1) of the truss structure’s inner element (2) can be equilateral, isosceles, or scalene triangles. When these triangular forms (3.1) are used in a two-dimensional lattice structure (5) without disturbing the six-fold rotational symmetry, the elastic mechanical properties of the lattice structure become isotropic.

[0051] There is an angle between the triangles (3.1) on each edge of the truss structure’s inner element (2). The angle between triangles (3.1) can be the same as the angle between the edges of the inner element and is preferably called the a (alpha) angle. The angle between the triangles (3.1) can be increased or decreased. Changing the angle between the triangles (3.1) can also be expressed as rotating the triangles (3.1). The angle a between the triangles (3.1) can be decreased by bringing them closer to each other at their vertices, or the angle a between the triangles (3.1) can be increased by moving them away from each other at their vertices.

[0052] The triangles (3.1) on the edge and bottom edges of the truss structure’s inner element (2) can be brought closer or further apart to each other, thus widening or narrowing the angle between the triangles (3.1). The angle between triangles (3.1) can preferably be between 0 and 180 degrees (it cannot be equal to 0 or 180 degrees). The angle between the triangles (3.1) can be changed, increased or decreased until the edges of the triangle (3.1) touch each other.

[0053] For example, in an embodiment of the invention where the truss structure’s inner element (2) is in the form of an irregular hexagon, there are a total of six triangles (3.1) in the truss structure (1). The angle a between the closest groups of binary triangles (3.1) is 60 degrees. When the triangles (3.1) are rotated by 5°, each triangle (3.1) rotates by 5° and the angle between the closest binary triangle (3.1) groups decreases to 50°. Thus, the structure and form of the truss structure’s inner element (2) changes and materials with different mechanical properties are obtained.

[0054] The number of edges of the truss structure’s inner element (2) is important in determining the angle between the inner element edges (2.1) and the angle between the triangles (3.1). For example, in one embodiment of the invention, the truss structure’s inner element (2) is in the form of an irregular hexagon and three internal angles of the inner element are 160° and the other three internal angles are 80°. In this embodiment, the angle a between the nearest pairs of triangles (3.1) is 80 degrees. In another embodiment of the invention, the truss structure’s inner element (2) is in the form of an irregular dodecagon and the six internal angles of the inner element are 195° and the other six internal angles are 105 degrees. In this embodiment, the angle a between the nearest pairs of triangles (3.1) is 45 degrees. By changing these angles, materials with different mechanical properties are obtained. The angles in question can be rotated until the edges of the triangles (3.1) on the edges of the truss structure’s inner element (2) are very close to touching each other, without touching each other.

[0055] In one embodiment of the invention, the form of the truss structure’s inner element (2) preferably increases in increments of three. In one embodiment, the truss structure’s inner element (2) can be changed from an irregular hexagon to an irregular nonagon by increasing the number of edges (2.1) by three, and then further increasing the number of edges by three to form an irregular dodecagon.

[0056] The number of edges of the truss structure’s inner element (2) does not have to increase by three. If the truss structure’s inner element (2) is in a regular or irregular octagonal form, the number of edges can be increased by four. In one embodiment, when the inner element (2) is an irregular octagon, it can be converted into an irregular dodecagon by increasing the number of edges (2.1) by four, further changed into an irregular hexadecagon by increasing the number of edges by four again, and continued in this way to reach the desired number of edges.

[0057] In one embodiment of the invention, the triangles (3.1) formed by the outer struts (3) on the truss structure (1) are joined together at their vertices to form the unit cell (4). The unit cells (4) are then connected at the vertices of the triangles (3.1) to create a two-dimensional (2D) lattice structure (5).

[0058] In the truss structure (1) of this invention, there is an inner element (2) whose edges form a polygon, preferably with at least six edges. A triangle (3.1) is preferably arranged on each edge, with its base aligned along the edge (2.1), forming the truss structure (1). To create the unit cell (4), multiple truss structures (1) are connected by joining the triangle vertices. The unit cells (4) are then combined in the same way to produce a two-dimensional lattice structure (5).

[0059] In one embodiment of the invention, auxiliary struts (6) are added into the inner element (2) of the truss structure (1) to increase its resistance to deformation. As a result, the mechanical properties of the lattice material (5) formed from the truss structure (1) can be enhanced. The mechanical properties of both the truss structure (1) and the resulting lattice material (5) vary depending on the number of auxiliary struts (6), their orientation, and the region in which they are placed. To ensure that a lattice material (5) improved with auxiliary struts (6) retains in-plane isotropic mechanical properties, the added struts should not disrupt the six -fold rotational symmetry of the unit cell (4). Auxiliary struts (6) can be arranged to connect the vertices of the preferred triangles (3.1). They can also extend from the junction of two inner element edges (2.1) to the junction of another pair of edges within the unit cell (4).

[0060] By adding auxiliary struts (6) to the truss structure (1), the two-dimensional lattice structure (5) is strengthened and a two-dimensional lattice structure (5) with different mechanical properties is obtained.

[0061] In one embodiment, spherical lattice structures can be created by joining truss structures (1) together. In another embodiment, lattice materials (5) produced from the truss structure (1), which exhibit a wide range of mechanical properties, can be folded along any axis in the plane to form lattice structures in the shape of cylindrical tubes. The two-dimensional lattice structure (5) can be folded around the x-axis to create the first cylindrical tube, or around the y-axis to form the second cylindrical tube-shaped lattice structure.

Claims

CLAIMS1. A truss structure (1), which forms the basis of lattice materials obtained by tessellating unit cells in the plane and ensures that the elastic moduli per unit weight of the resulting lattice materials are greater than those of many existing cellular solids with stochastic distribution and many existing lattice materials, characterized by comprising: at least one truss structure’s inner element (2) in an irregular polygonal geometric form, formed by combining inner element edges (2.1) containing at least six inner element edges (2.1), outer struts (3) placed on the inner element edges (2.1) of the truss structure’s inner element (2) to form a triangle (3.1) on each inner element edge (2.1),- triangle (3.1) structure on each inner element edge (2.1) and- triangles (3.1) arranged such that each is positioned at an angle relative to another triangle (3.1) located on an adjacent inner element edge (2.1).

2. A truss structure (1) according to claim 1, characterized in that the inner element (2) is an irregular polygon and a triangle (3.1) is located on each inner element edge (2.1).

3. A truss structure (1) according to claim 1, characterized in that the inner element (2) is an irregular polygon having six inner element edges (2.1), and the unit cell (4) is obtained by combining six such inner elements (2).

4. A truss structure (1) according to claim 1, characterized in that auxiliary struts (6) are placed in different regions, in different numbers, and in different orientations within the inner element (2), increasing the deformation resistance of the truss structure (1) to which they are added.

5. A truss structure (1) according to claim 1, characterized in that the inner element (2) is in a regular or irregular polygonal geometric form selected from a hexagon, octagon, nonagon, dodecagon, pentadecagon, hexadecagon, octadecagon, or 24-gon, and is formed by placing outer struts (3) on each inner element edge (2.1) to create at least one triangle (3.1), and wherein the unit cell (4) is obtained by combining such truss structures (1).

6. A truss structure (1) according to claim 1, characterized in that the inner element (2) is in the form of an irregular polygon having six edges, or having a number of edges that are multiples of three greater than six (nine, twelve, fifteen, eighteen, twenty-one, twenty-four, twenty-seven, or more), or multiples of four greater than six (eight, twelve, sixteen, eighteen, twenty, twenty-four, twenty-eight, or more), and is formed by placing outer struts (3) on each inner element edge (2.1) to create at least one triangle (3.1), wherein a unit cell (4) is obtained by combining such truss structures (1).

7. A truss structure (1) according to claim 1, characterized in that the lattice structure (5) is obtained in the form of a first cylindrical tube or a second cylindrical tube by folding around an axis in the plane.

8. A truss structure (1) according to claim 1, characterized in that an angle is defined between the triangles (3.1) on each edge of the inner element (2).

9. A truss structure (1) according to claim 1, characterized in that the acute angle between the edges of the inner element (2) corresponds to the acute angle between the nearest pairs of triangles (3.1).

10. A truss structure (1) according to claim 1, characterized in that the angles between the inner element edges (2.1) of the inner element (2) are different from each other and from the angles between the triangles (3.1).

11. A truss structure (1) according to claim 1, characterized in that the a angle between the triangles (3.1) is adjustable, such that it can be decreased by bringing their vertices closer together or increased by moving them farther apart.

12. A truss structure (1) according to claim 1, characterized in that the angle between the triangles (3.1) on the side and bottom edges of the inner element (2) can be adjusted by moving the triangles closer together or farther apart.

13. A truss structure (1) according to claim 1, characterized in that the angle between the triangles (3.1) is between 0° and 180°, or that the angle between the triangles (3.1) can be varied until the edges of the triangles (3.1) come into contact with each other.

14. A truss structure (1) according to claim 1, characterized in that the angles between the inner element edges (2.1) and the angles between the triangles (3.1) are determined according to the number of edges of the inner element (2).

15. A truss structure (1) according to claim 1, characterized in that the form and the geometric configuration of the inner element (2) can be changed by increasing the number of its edges (2.1) in increments of three or four.

16. A truss structure (1) according to claim 1, characterized in that a unit cell (4) is obtained by connecting the vertices of the triangles (3.1), and a two- dimensional lattice structure (5) is formed by further joining the vertices of the triangles (3.1) within the unit cell (4).

17. A truss structure (1) according to claim 1, characterized in that auxiliary struts (6) are added so as to connect the vertices of the preferred triangles18. A truss structure (1) according to claim 1, characterized in that auxiliary struts (6) are arranged in the unit cell (4) to extend from the junctions of certain inner element edges (2.1) toward the junctions of other inner element edges (2.1).

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