KR100767186B1 - A light weight sandwich panel with a core constructed of wires and the manufacturing method of the same - Google Patents

Abstract

A lightweight sandwich panel having a core composed of wires and a manufacturing method thereof are provided to improve the rigidity by excluding interference with wires, to enhance the mechanical performance by adjusting the bending angle, arrangement and intervals, and to cut down manufacturing costs by bending wires simply. A sandwich panel is composed of upper and lower face sheets and a truss core. A wire(1) is placed in the upper and lower face sheets, arranged in parallel with an x-z plane, and formed of triangular wave in projecting a plane arranged vertically to a z-axis. The wire is arranged in the sandwich panel and formed of triangular wave having sides arranged alternately in projecting on a plane arranged vertically to a y-axis. The wires are arranged in parallel and placed at regular intervals on the x-z plane. The wires are arranged alternately or twisted repeatedly, and inclined between the parallel wires.

Description

Light weight sandwich plate with intermediate layer of wire and manufacturing method thereof {A LIGHT WEIGHT SANDWICH PANEL WITH A CORE CONSTRUCTED OF WIRES AND THE MANUFACTURING METHOD OF THE SAME}

1 is a perspective view of several conventional sandwich plate structures.

2 to 4 are each a perspective view of a sandwich plate material having a pyramid, an octet and a kagome truss structure as an intermediate layer and a face plate attached to the upper and lower sides thereof.

FIG. 5A is a diagram illustrating a conventional method of producing a pyramid truss by bending an expanded metal network; FIG.

Figure 5b is a view showing a conventional method for producing a pyramid truss by bending and then expanding the sheet to form an expanded metal network.

6 shows a conventional method of producing a pyramid truss by bending a woven wire mesh.

7 shows a conventional method of weaving a wire bent in a triangular wave in two orthogonal directions to produce a structure similar to a pyramid truss.

8 is a view showing a conventional method for producing an octet truss by weaving a wire bent in a triangular wave form in three directions.

FIG. 9 shows a conventional method of three-dimensional weaving wires in six directions to form a truss structure similar to a cargo truss.

10 is a perspective view of a representative embodiment of the lightweight sandwich plate according to the present invention.

FIG. 11 is a projection view showing the shape and arrangement of wires forming an intermediate layer of the light weight sandwich plate of FIG. 10; FIG.

Figure 12 is a comparison of the unit structure and pyramid truss of the triangular wave-shaped wire of Figure 11;

FIG. 13A is a perspective view and a plan view of an intermediate layer formed by staggering front and rear wires alternately with the wires of FIG. 11 one by one; FIG.

FIG. 13B is a perspective view and a plan view of an intermediate layer formed of a complete pyramid truss composed of truss elements of wire diameter and length as in FIG. 13A;

14 is a perspective view of various embodiments of the present invention arranged to adjust the spacing between the wires constituting the intermediate layer.

15 is a view in which wires formed to have a triangular wave shape are arranged in parallel to each other back and forth at irregular intervals without varying intervals.

16A is a view in which wires shaped to have a triangular wave shape are alternately arranged at two azimuth angles on the x-z plane.

FIG. 16B is a diagram in which wires shaped to have a triangular wave shape are disposed radially on an x-z plane; FIG.

FIG. 17A illustrates a process of first bending a wire to produce an intermediate layer of a lightweight sandwich plate according to the present invention. FIG.

FIG. 17B is an explanatory diagram illustrating a step of performing secondary bending of a wire bent primarily in accordance with FIG. 17A. FIG.

The present invention relates to a lightweight sandwich plate having an intermediate layer made of wire and a method of manufacturing the same.

In general, sandwich plate structures are composed of a material having high strength / density on the upper and lower surfaces, and a porous material or a lattice material having a low density such as styrofoam in the middle layer. 1 shows the shape of several sandwich plate structures with a lattice interlayer. Most lattice interlayers and porous materials consist of several closed rooms, making it difficult to utilize space.

Recently, a periodic truss structure has been introduced as a new intermediate layer material (H.N.G. Wadley, N.A.Fleck, A.G.Evans, 2003, Composite Science and Technology, Vol. 63, pp.2331-2343). The truss structure, which is designed for optimum strength through precise calculations, has the advantage that the internal space is opened and the space is utilized while having the mechanical properties comparable to the honeycomb lattice.

The most common truss type is the pyramid truss. Four regular triangular lattice forms an inclined plane, and the square lattice forms the lower (or upper) plane, which is advantageous for making a rectangular plate structure.

Another truss structure includes an octet truss (R. Buckminster Fuller, 1961, US Patent 2,986,241) in which a tetrahedron and an octahedron are combined. Each element of the truss forms an equilateral triangle.

In the 21st century, the Kagome truss, which transformed the octet truss, was announced (5S Hyun, AM Karlsson, S. Torquato, AS Evans, 2003, Int. J. of Solids and Structures, Vol. 40, pp.6989- 6998).

2, 3, and 4 show the shape of the sandwich plate material having a pyramid, an octet, and a kagome truss structure as an intermediate layer, and a face sheet attached to the top and bottom thereof, respectively. When compressive or tensile loads are applied, octets and kagome trusses are known to have slightly superior strength to weight compared to pyramid trusses. However, when shear loads are applied, the strength varies greatly depending on the direction. Therefore, when a lateral load such as three-point bending is applied to the sandwich plate, a truss having a small change in shear strength along the direction, such as a pyramid truss, is advantageous.

Several methods can be used to fabricate sandwich plates with pyramidal truss interlayers (Ref. H, HG Wadley et al., 2003, "Fabrication and structural performance of periodic cellular metal sandwich structure", Composite Science Technology, Vol. .63, pp. 2331-2343).

First, it is a method of manufacturing the entire structure including the truss intermediate layer using resin as a raw material and casting the metal into a mold. It is a metal that is expensive to manufacture and has a very good castability, and is prone to defects.

Second, it is a method of attaching a face plate to the top and bottom after forming a truss intermediate layer by forming periodic netted holes in a thin plate to form a net shape and bending it to form a V-shaped unevenness along a diagonal line. There is a problem that material loss occurs in the process of drilling the plate.

Third, in order to eliminate material loss of the second method, a method of making a metal plate in the form of a net is to use an expanded metal process instead of perforation.

Fourth, a wire mesh woven from two perpendicular wires is bent along a diagonal of the intersection to form “V” shaped irregularities to form a pyramid truss, and the upper and lower plates are attached to an intermediate layer. The second, third, and fourth methods are basically the same in that they first form a net with square holes and then bend into irregularities.

5 and 6 show the third and fourth methods, respectively. Although these two methods are known to minimize manufacturing costs, they are limited to materials having excellent formability, respectively, and there is a problem in that coarse wires cannot be used as a material because wires intersect at the vertices of the truss.

US Patent No. US 6,644,535 B2 (J.C. Wallach and L.J. Gibson, 2003) first proposed a method of making a pyramid truss-like structure by bending a wire in a triangular wave form and then weaving the wire in two orthogonal directions. 7 shows the form.

As a material constituting the truss, the wire has the following advantages.

First, the wire is easy to manufacture and few defects. Second, it is easy to increase the strength through work hardening or to obtain a high strength material such as a piano wire. Third, it is easy to carry out plastic working such as bending. Therefore, a method of constructing a periodic truss structure based on wires has recently been proposed.

In Korean Patent Application No. 10-2004-0105226 (Kang Gi-ju, Na Sung-jun, Kim Byung-guk, Ahn Dae-gun, Cho Young-jae, 2004, Manufacturing method of ultra-light sandwich plate), an octet truss is formed by weaving a wire bent in a triangular wave form in three directions. We have presented how to configure. 8 shows the form.

PCT Patent Application No. PCT / KR2004 / 002864 (Kang Gi-ju, Lee Yong-hyun, 2004) has proposed a method of constructing a truss structure similar to a Kagome truss by three-dimensional weaving wires in six directions. 9 shows the form.

A common problem in truss construction methods using the above wires as materials is that interference occurs between the wires because the wires are woven, woven or overlapped with each other. Therefore, there is a difference from the ideal truss structure originally intended to be implemented, or the wire corresponding to the straight strut (strut) constituting the truss is bent. The interference problem between the wires becomes more severe as the wires become thicker, and thus, it is difficult to use them as structural members requiring high strength.

In order to solve the above problems, an object of the present invention is to use a wire as a material, a truss having a structure that can completely eliminate the interference between the wires and easy to mass production and has a mechanical performance that is inferior to the existing truss structure There is provided a method for producing a lightweight sandwich board having an intermediate layer.

The gist of the present invention for achieving the above object is as follows.

(1) a sandwich plate composed of an upper / lower face sheet and a truss-shaped core layer;

In space, represented by the x-axis, z-axis, and y-axis perpendicular to this plane, which are coplanar and perpendicular to each other,

The upper and lower faceplates have a triangular wave shape when projected on a plane parallel to the xz plane and perpendicular to the xz plane, and the sides forming the triangular wave when projected on a plane perpendicular to the y axis. A sandwich plate, characterized in that there is a truss-shaped intermediate layer in which wires (1) molded to have a triangular wave shape are alternately changed every two nodes.

(2) The sandwich plate according to (1), wherein the wires (1) are arranged parallel to each other back and forth at regular intervals on the x-z plane.

(3) The sandwich plate according to (2), wherein the wires (1) are repeatedly turned upside down or staggered.

(4) The sandwich plate material according to (2), wherein a wire (1) facing in a direction inclined with respect to the wire (1) is disposed between the wires (1) arranged in parallel.

(5) The sandwich plate according to (1), wherein the wires (1) are arranged in parallel with each other back and forth at intervals varied on the x-z plane.

(6) The sandwich plate material according to (1), wherein the wire (1) is disposed radially on an x-z plane.

(7) The sandwich board according to any one of (1) to (6), wherein the sandwich plate is formed by filling the empty space of the intermediate layer with any one of a porous material, a resin, a metal, and a ceramic.

(8) A method for producing a sandwich plate according to any one of (1) to (6);

A first step of bending the wire (6) in a triangular wave form in one plane; A second step of repeatedly bending (8) the wire bent in said first step every two nodes again in the out-of-plane direction in the forward and reverse directions; A third step of arranging the intermediate wires by arranging the wires bent in the second step on the lower face plate; And a fourth step of placing the upper face plate on the wire intermediate layer arranged in the third step and coupling the middle layer and the upper and lower face plate contacts.

Hereinafter, the configuration and the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

10 is a perspective view showing an example of a lightweight sandwich plate according to the present invention.

FIG. 11 is a projection view showing the shape and arrangement of the wire 1 constituting the intermediate layer of the plate member of FIG. 10. The wire 1 has a triangular wave shape in two directions perpendicular to each other and is arranged at regular intervals on the x-z plane to form a truss.

In FIG. 12, the triangular truss 3 and the unit structure of the triangular wave-shaped wire of FIG. 11, that is, two triangular shapes consisting of two node truss elements, are zigzag in the y-axis. The comparison is shown. It can be seen that when one structure is moved in parallel with respect to the left and right symmetry lines of FIG. 12A and overlaps with the other structure, the same shape as the pyramid truss of FIG. 12B is obtained.

On the other hand, since the pyramid trusses have the same vertices of the two triangular structures, the four truss elements forming the truss support each other and have a stable shape, while the wire structure of the present invention separates the left and right triangular vertices to support each other. Because it is unstable. However, this wire structure becomes a stable structure because the vertices are attached to the upper and lower face plates as an intermediate layer between the upper and lower face plates.

FIG. 13A alternately arranges the front / rear wires 4 alternately by interlayer wires of FIG. 11. That is, the contact points of the lower face plate of a wire-shaped structure and the contact points of the wire structure before and after the wire contact each other, and the contact points with the lower face plate have a form where four truss elements meet like a pyramid structure. .

FIG. 13b is a complete pyramid truss 5 composed of truss elements of the same wire diameter and length as in FIG. 13a. Comparing FIG. 13A with FIG. 13B, it can be seen that FIG. 13A is part of a complete pyramid truss 5. That is, when two structures of FIG. 13A overlap, the complete pyramid truss 5 is obtained. In theory, the structure of FIG. 13A is half the density, strength, and stiffness of the pyramid truss in the state where the relative positions of the vertices are fixed by bonding with the upper and lower face plates.

FIG. 14 illustrates an example in which the intervals of the wires constituting the intermediate layer are adjusted in three ways. If the spacing is half of FIG. 13A, in theory, the density, strength and stiffness will be like a complete pyramid truss. In addition, since the gap between the junction points with the upper and lower face plates is 1/2 of the pyramid truss, the buckling strength of the face plate increases when the sandwich plate is bent. Thus, by adjusting the bending angle, the arrangement interval and the arrangement method of the wire forming the intermediate layer of the sandwich plate of the present invention can have a desired mechanical performance.

Therefore, it is possible to apply easily to various fields by changing the structure of an intermediate | middle layer in consideration of load conditions with the size, shape, use, etc. of a sandwich board material. For example, if the load distribution applied to the sandwich plate is not uniform, as shown in FIG. 15, the gap between the plurality of wires 1 parallel to each other may be varied to form an intermediate layer of the sandwich plate. It may be.

In addition to the method of arranging the wires constituting the intermediate layer in parallel, it is also possible to control the mechanical properties of the sandwich plate by adjusting the angle between the wires.

For example, FIG. 16A shows an embodiment in which wires having different azimuth angles are interposed between parallel wires 1. As a result, the intermediate layer of the sandwich plate of Fig. 16A is composed of a plurality of wires oriented in two directions. In particular, when the sandwich plate is in the shape of axisymmetric or in the shape of a part of a circle, the wires 1 may be arranged radially, and FIG. 16B shows an embodiment including such a configuration.

The most important advantage of the wire structure of the sandwich plate intermediate layer proposed in the present invention is that since the contact between the wires can be basically minimized or completely excluded, it is possible to construct a truss without interference with each other regardless of the thickness of the wire. Therefore, the production is easy and the mechanical performance is excellent.

According to a preferred embodiment of the present invention, the hollow space of the intermediate layer of the sandwich plate is filled with any one of a porous material, a resin, a metal, and a ceramic so as to add heat insulation performance, noise and vibration blocking performance, and other mechanical properties improvement and functions of the plate. It may be.

The following is an embodiment of a method of manufacturing a sandwich plate consisting of a wire proposed in the present invention.

FIG. 17 illustrates a bending process of wires. First, the wires are bent in a triangular wave shape in one plane as shown in FIG. 17A. FIG. 17B illustrates a process of laying the bent wire 7 lying on the horizontal plane and performing secondary bending as shown in FIG. 17A. Between the “V′-shaped molds 6 and 8, the bending interval is two nodes of the first bent wire. In the out-of-plane direction, it is bent in a zigzag shape by repeating the forward and reverse directions in the out-of-plane direction.

The bent wires 9 are arranged between the thin upper and lower face plates to form an intermediate layer, and the contact parts with the upper and lower face plates are joined by welding, brazing, resin bonding, and the like to complete the sandwich plate.

As seen above, the present invention is for a light weight sandwich plate has the following advantages.

(1) As an intermediate layer material, it is easy to manufacture and uses a wire with few defects, high strength, and easy processing.

(2) Since it has a structure that can completely eliminate interference between wires, it is possible to realize a structure having a thick truss element or a truss element having a low slenderness without using wires as a truss element, thereby obtaining a high strength structure.

(3) It has high design flexibility to adjust bending angle, arrangement interval and arrangement method of wire structure to have desired mechanical performance.

(4) The intermediate layer wire structure can be obtained by only two simple bending processes without complicated processes such as weaving or weaving wires together, thus reducing manufacturing cost and facilitating mass production.

Claims (8)

A sandwich plate composed of an upper / lower face sheet and a truss-shaped core layer; In the space represented by the x-axis, z-axis, and y-axis perpendicular to this plane, which are coplanar and perpendicular to each other, the upper and lower faceplates may be projected on a plane parallel to the xz plane and perpendicular to the z-axis in the middle. At the same time, the wire 1 formed to have a triangular wave shape in which the direction changes alternately every two nodes of the triangular wave when projected on a plane perpendicular to the y-axis when having a triangular wave shape. Sandwich board, characterized in that there is a truss-shaped intermediate layer. The method of claim 1, The sandwich plate, characterized in that the wire (1) is arranged parallel to each other back and forth at regular intervals on the x-z plane. The method of claim 2, Sandwich plate, characterized in that the wire (1) is repeatedly turned upside down or staggered. The method of claim 2, A sandwich plate, characterized in that a wire (1) facing in a direction inclined with respect to the wire (1) is disposed between the wires (1) arranged in parallel. The method of claim 1, The sandwich plate, characterized in that the wires (1) are arranged in parallel to each other back and forth at varying intervals on the x-z plane. The method of claim 1, The sandwich plate, characterized in that the wire (1) is disposed radially on the x-z plane. The method according to any one of claims 1 to 6, A sandwich plate formed by filling an empty space of an intermediate layer with any one of a porous material, a resin, a metal, and a ceramic. A method for producing a sandwich plate according to any one of claims 1 to 6; A first step of bending the wire (6) in a triangular wave form in one plane; A second step of repeatedly bending (8) the wire (7) bent in the first step every two nodes again in the out-of-plane direction in the forward and reverse directions; A third step of arranging the intermediate layers by arranging the wires (9) bent in the second step on the lower face plate; And a fourth step of placing the upper face plate on the wire intermediate layer arranged in the third step and combining the middle layer and the upper and lower face plate contacts.

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