KR20100019041A - Truss type periodic cellular materials having polyhedrons or spheres in their internal vacancies and a manufacturing method of the same - Google Patents

Abstract

PURPOSE: A truss type periodic cellular material and a method of manufacturing the same are provided to improve energy absorption force due to structural stability and deformation. CONSTITUTION: A method of manufacturing truss type periodic cellular material comprises the following steps of: weaving or cross-placing a wire(21) and forming a two-dimensional plane of a net shape with plural holes; placing polyhedron or sphere filler(31) on a part of plural holes formed on the two-dimensional plane; laminating the two-dimensional plane with layers; forming a 3D truss structure(11) by weaving the two dimensional plane with wire; and welding the polyhedron or the sphere filler and the wire respectively or to each other.

Description

TRUSS TYPE PERIODIC CELLULAR MATERIALS HAVING POLYHEDRONS OR SPHERES IN THEIR INTERNAL VACANCIES AND A MANUFACTURING METHOD OF THE SAME}

The present invention relates to a porous material and a method of manufacturing the same, and more particularly, to a truss-shaped periodic porous material and a method for producing the same, characterized in that the inner hollow space of the truss structure is filled with a filler. will be.

Porous materials are materials that are light and have relatively high strength due to the large number of small voids formed therein. Among such porous materials, materials having uniform sizes, shapes, and arrangements of internal void spaces are called periodic cellular materials.

Recently, a periodic porous material in the form of a truss has been introduced as a new intermediate material (H. N. G. Wadley, N. A. Fleck, A. G. Evans, 2003, Composite Science and Technology, Vol. 63, pp. 2331 ~ 2343).

The truss structure is designed to have the best strength through precise calculations, and has the mechanical properties comparable to that of a honeycomb lattice.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram for illustrating the monolayer structures of pyramids, octets, and kagome trusses. Hereinafter, the type of the truss structure will be described with reference to FIG. 1.

Pyramid trusses are the most common truss structures. Specifically, the pyramid truss has an advantageous advantage in the production of a rectangular plate structure, because the four regular triangular gratings form a sloped surface around one vertex and one square grating constitutes a bottom or top surface.

In addition, the octet truss is a structure in which a tetrahedron and an octahedron are combined, and each truss element forms an equilateral triangle with each other (R. Buckminster Fuller, 1961, US Patent 2,986,241).

In the 21st century, Kagome truss was published (S. Hyun, AM Karlsson, S. Torquato, AG Evans, 2003, Int J. of Solids and structures, Vol. 40, pp.6989-6998). It is known that the octate truss is modified, and the stiffness change of the structure according to the direction is less than that of the pyramid truss and the octet truss, and the buckling resistance, the stability of the deformation after buckling, and the energy absorption ability are particularly excellent.

On the other hand, in recent years, there has been proposed a method for producing a truss-shaped periodic porous material using a wire such as a piano wire, which is easy to mass produce, process, and achieve high strength. This is specifically disclosed in Patent Nos. 566729, 633657, 700212, 767186, Patent Application No. 2006-0119233, and the like. 2 to 6 show periodic porous materials produced by the method according to the patents and patent applications. In this case, if a wire made of a fiber reinforced plastic composite material is used, a lighter truss-shaped periodic porous material may be manufactured.

When a load such as compression or shear is applied to the truss-shaped periodic porous material as described above, the porous material is often damaged by the buckling of the truss element. In particular, elastic buckling is likely to occur when the truss element has high slenderness or when the material of the wire is a high strength fiber or a fiber reinforced resin used for a high strength metal or a composite material such as a piano wire. When elastic buckling occurs as described above, the strength of the periodic porous material tends to decrease rapidly, which causes a problem that the stability required for the structural material is significantly lowered and the amount of strain energy absorption is reduced.

In addition, ceramics and some high-strength metals are difficult to be manufactured and processed in large volumes, and thus there is a limit to their application as structural materials. Therefore, these materials have to be utilized in a relatively small size through sintering (sintering). For example, when a relatively large structure such as a structural plate is required, it is bonded or laminated with an adhesive as in brick or mortar, or reinforced by attaching a fiber reinforced composite resin (FRP), a composite plate, or a metal plate to the surface. use. However, the structure produced in this manner is vulnerable to impact loads, and once the failure is initiated, there is a disadvantage that it reaches a final failure at a high speed.

In addition, recently, a process of making a metal sphere with a hollow inside by spraying a metal powder on the surface of a styrofoam sphere and heating it, and then burning the styrofoam sphere has been developed. This is called MHS (Metal Hollow Sphere), and it is possible to manufacture a kind of porous metal by joining a plurality of MHS with resin or by applying heat and pressure (KM Hurysz, JL Clark, AR Nagle, CU Hardwicke, KJ Lee, JK). Cochran et al., Steel and titanium hollow sphere foams.In: A. Evans, D. Schwartz, D. Shih and H. Wadley, Editors, Porous and cellular materials for structural applications MRS Proceedings vol. 521, Materials Research Society, Pittsburgh, PA (1998), pp. 191203). As described above, the porous metal made of MHS is superior in strength and deformation energy absorption than conventional foam metals, but its internal space is closed, thereby limiting its utilization.

An object of the present invention is to provide a truss type periodic porous material having a structural stability and an energy absorption force due to deformation and a method of manufacturing the same by solving the above problems.

The gist of the truss-shaped periodic porous material filled with a polyhedron or spherical material according to the present invention is as follows.

(1) In the periodic porous material in the form of a truss in which a plurality of empty spaces are formed,

At least a portion of the plurality of empty spaces are filled with a truss-shaped periodic porous material, characterized in that filled with a polyhedral or spherical filler.

(2) The truss-shaped periodic porous material according to the above (1), wherein the polyhedral or spherical filler is made of any one selected from metal, ceramic, and synthetic resin.

(3) A method for producing a truss-shaped periodic porous material according to the above (1) or (2),

Weaving or crossing the wires to form a two-dimensional plane in the form of a net having a plurality of holes;

Arranging polyhedral or spherical fillers in at least some of the plurality of holes formed in the two-dimensional plane;

Stacking a two-dimensional plane in which the polyhedral or spherical fillers are arranged in a plurality of layers;

Forming a three-dimensional truss structure by weaving the two-dimensional plane stacked in the plurality of layers with a wire inserted in an out-of-plane direction;

Method for producing a periodic porous material of the truss form comprising a.

(4) after the truss structure is formed, further comprising the step of joining the polyhedral or spherical filler and the wire to each other or to each other, wherein the truss-shaped periodic porous material as described in the above (3). .

(5) The spherical filler,

After the metal powder is spray-coated and heated on the surface of the styrofoam sphere, the inside of the truss-shaped truss form (3) is characterized in that the interior of the hollow metal sphere (MHS) formed by burning the styrofoam sphere is formed. Method for producing a porous material.

According to the truss-shaped periodic porous material filled with a polyhedral or spherical material in the interior space according to the present invention as described above and a method of manufacturing the same, it is possible to suppress the buckling of the truss element during compression or shear load, even after buckling occurs By suppressing a sudden drop in strength, the stability as a structural member can be improved and the amount of energy absorption due to deformation can be increased. In addition, the present invention can be utilized as a structural member such as a plate material can be reduced in weight, by using the already established bonding technology has the advantage of reducing the production cost and easy mass production.

Hereinafter, a preferred embodiment of the truss-shaped periodic porous material filled with a polyhedral or spherical material according to the present invention and a manufacturing method thereof will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals designate like elements throughout the specification.

First, the truss-shaped periodic porous material will be described.

FIG. 7 illustrates a structure of a periodic porous material in the form of a truss according to an embodiment of the present invention.

Referring to FIG. 7, a periodic porous material in the form of a truss according to the present invention is composed of a truss structure 10 and a filler 30.

The truss structure 10 is formed by the crossing or weaving method of the wires 20, and the filler 30 is positioned and filled in a plurality of empty spaces formed in the truss structure 10.

The wire 20 serves to prevent the filler 30 from being separated from a specific position by weaving the fillers 30 together.

The filler 30 may be made of metal, ceramic, synthetic resin, or the like in consideration of the impact load to be applied. In addition, the filler 30 is formed in a spherical shape according to the empty space formed in the truss structure (10). In this case, although the spherical filler is exemplified in the present embodiment, the shape of the filler is not limited to the spherical shape and may be a polyhedron depending on the shape of the empty space. This will be described later.

The filler 30 manufactured in the material and shape as described above may be filled in some or all of the plurality of empty spaces formed in the truss structure 10 according to the required strength.

Subsequently, various embodiments of the truss-shaped periodic porous material according to the present invention will be described.

8 to 10 are views for showing the structure of the periodic porous material of the truss type according to another embodiment of the present invention.

8 shows a structure of a periodic porous material in which a hexahedral filler 31 is filled in a hexahedral truss structure 11 composed of three straight wires 21 perpendicular to each other. When the filler filled in the truss structure is a polyhedron in this manner, as shown in the right side of FIG. 8, the groove 34 having a shape corresponding to the outer circumferential surface of the wire 21 is formed in the corner portion of the filler 31. Each filler 31 may be in close contact with the adjacent filler 31 without interference of the wire 21.

In another embodiment of the present invention, FIG. 9 illustrates a structure of a periodic porous material filled with a spherical filler 32 in a pseudo-octet truss structure 12 composed of continuous straight wires 22.

10, as another embodiment of the present invention, a structure of a periodic porous material in which a pyramidal truss structure 13 is filled with a pyramidal filler 33 and a tetrahedral filler 33 ′ is shown. Here, only the structure of the first floor is shown for convenience of description. In the present embodiment, since the fillers 33 and 33 'of the non-spherical polyhedron are used similarly to the embodiment of FIG. 8, grooves corresponding to the shape of the wire 23 at the corners of the fillers 33 and 33' ( It is preferable that the fillers 33 and 33 'be brought into close contact with each other by forming 34).

As described above, the truss-shaped periodic porous material according to various embodiments of the present invention is composed of a truss structure and a filler, thereby taking all the advantages of each member. For example, when a truss structure is formed by using carbon fiber, piano wire, or the like as a wire, a porous material having an ideal physical property having both a strong property of tension of the wire and a high compressive strength property of a filler filled in an empty space of the truss structure. Can make

In the above, the truss-shaped periodic porous material in which the internal space of the present invention is filled with a polyhedral or spherical material has been described.

Hereinafter, a method of manufacturing a truss-shaped periodic porous material according to the present invention as described above will be described in detail.

According to the present invention, there is provided a method of manufacturing a truss-shaped periodic porous material, comprising: weaving or crossing wires to form a net-shaped two-dimensional plane having a plurality of holes, wherein at least one of the plurality of holes formed in the two-dimensional plane is formed. Arranging polyhedral or spherical fillers on a part, laminating a two-dimensional plane on which the polyhedral or spherical fillers are disposed in a plurality of layers, weaving a two-dimensional plane stacked in the plurality of layers with a three-dimensional truss Forming a structure.

In addition, the present invention may further include the step of bonding the wire and the polyhedral or spherical filler by the method of resin bonding, brazing, soldering, welding, etc. after the formation of the truss structure.

Here, when the hollow metal sphere (MHS) is used as the filler, it is possible to obtain a truss-shaped periodic porous material that is lighter and has improved absorption of strength and strain energy.

The method for manufacturing a truss-shaped periodic porous material according to the present invention as described above may be carried out in various forms. Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

11 to 14 are diagrams for illustrating a method of manufacturing a periodic porous material according to the embodiment of FIGS. 7 to 10, respectively.

First, referring to FIG. 11, the spiral wire 20 in three directions is woven in an in-plane to form a two-dimensional kagome truss structure, and a spherical filler is formed in a plurality of hexagonal holes formed in the two-dimensional kagome truss structure. Position and place the 30, then stack it in a plurality of layers and rotate the spiral wire 20 in three out-of-plane directions to form a structure 10 similar to a three-dimensional kagome truss shape. Can be formed.

In Fig. 12, as another embodiment of the present invention, two parallel wires 21 in a plane are arranged perpendicular to each other, and a plurality of hexahedral fillers 31 are disposed thereon, and then a third in the out-of-plane vertical direction is formed. A method of forming the porous structure 11 by inserting the wire 21 'is illustrated. In this case, since the wires 21 and 21 'do not restrain each other, the positions of the wires 21 and 21' may be fixed by using a separate support frame (not shown) on the outside of the porous structure 11. There is a need.

13, another embodiment of the present invention is shown.

Specifically, referring to FIG. 13, the three-dimensional straight wires 22 intersect to overlap each other to have an azimuth angle of 60 degrees or 120 degrees, and then spherical filler 32 is formed in a plurality of triangular holes formed accordingly. It is possible to form a structure 12 similar to a three-dimensional octet truss by arranging it, stacking it in a plurality of layers, and inserting the straight wire 22 again in three out-of-plane directions.

Here, when arranging the spherical filler 32 in a plurality of triangular holes, it is not disposed in all the holes in consideration of the volume of the filler 32, and the adjacent holes of the holes filled with the filler 32 are left empty. It is preferable.

In addition, even in this embodiment, since the wires 22 are not fixed, it is preferable to fix the position of the wire 22 by using a separate support frame (not shown) as in the embodiment of FIG. 12.

As still another embodiment of the present invention, FIG. 14 illustrates a method of forming a porous structure using pyramidal filler and tetrahedral filler. First, the pyramidal filler 33 is disposed on the flat plate 40 while maintaining a predetermined interval, and then the tetrahedral filler 33 'is disposed in the space formed between the plurality of pyramidal fillers 33. Subsequently, the pyramid truss structure is positioned on the plate on which the fillers 33 and 33 'are disposed, the tetrahedral filler 33' and the pyramidal filler 33 are sequentially arranged, and then a separate plate 41 is disposed thereon. The porous structure 13 can be obtained.

After forming the porous structure according to the embodiment of FIGS. 11 to 14 described above, as described above, the wire, the truss structure, the filler, the flat plate, and the like can be finally bonded to each other and fixed. Specifically, brazing may be used when the filler is a ceramic having a high melting point or a metal having a higher melting point than the metal constituting the wire or truss structure. In addition, a method such as resin bonding, soldering, welding, or the like may be used depending on the material or use of the wire, truss structure, and filler.

As described above, a preferred embodiment of a truss-shaped periodic porous material filled with a polyhedron or a spherical material and a method for manufacturing the same according to the present invention have been described in detail with reference to the drawings. It is to be understood that the present invention is not limited to the present invention and includes all modifications that can be grasped from the matters described in the claims.

1 is a view for showing the monolayer structure of the pyramid, the octet, and the kagome truss,

2 to 6 are views for showing a periodic porous material in the form of truss made of a wire material,

7 to 10 are views for showing the structure of the periodic porous material of the truss type according to various embodiments of the present invention,

11 to 14 illustrate a method of manufacturing a periodic porous material according to the embodiment of FIGS. 7 to 10, respectively.

* Description of the main parts of the drawing

10, 11, 12, 13: truss structure 20, 21, 22, 23: wire

30, 31, 32, 33, 33 ': Filler 34: Groove

40, 41: reputation

Claims (5)

In the periodic porous material in the form of a truss in which a plurality of empty spaces are formed, At least a portion of the plurality of empty spaces are filled with a truss-shaped periodic porous material, characterized in that filled with a polyhedral or spherical filler. The method of claim 1, The polyhedral or spherical filler is a truss type periodic porous material, characterized in that made of any one selected from metal, ceramic, synthetic resin. A method of manufacturing a periodic porous material in the form of a truss according to claim 1, Weaving or crossing the wires to form a two-dimensional plane in the form of a net having a plurality of holes; Arranging polyhedral or spherical fillers in at least some of the plurality of holes formed in the two-dimensional plane; Stacking a two-dimensional plane in which the polyhedral or spherical fillers are arranged in a plurality of layers; Forming a three-dimensional truss structure by weaving the two-dimensional plane stacked in the plurality of layers with a wire inserted in an out-of-plane direction; Method for producing a periodic porous material of the truss form comprising a. The method of claim 3, wherein After forming the truss structure, further comprising bonding each of the polyhedral or spherical fillers and wires to each other or to each other. The method of claim 3, wherein The spherical filler, Method of producing a truss-shaped periodic porous material, characterized in that the metal hollow (Metal Hollow Sphere: MHS) formed by burning the styrofoam spheres by heating and spray coating the surface of the styrofoam spheres.

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