WO2008078883A1 - A light weight sandwich panel with a core constructed of wires and the manufacturing method of the same - Google Patents

A light weight sandwich panel with a core constructed of wires and the manufacturing method of the same Download PDF

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Publication number
WO2008078883A1
WO2008078883A1 PCT/KR2007/006413 KR2007006413W WO2008078883A1 WO 2008078883 A1 WO2008078883 A1 WO 2008078883A1 KR 2007006413 W KR2007006413 W KR 2007006413W WO 2008078883 A1 WO2008078883 A1 WO 2008078883A1
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WO
WIPO (PCT)
Prior art keywords
wires
truss
sandwich panel
core
plane
Prior art date
Application number
PCT/KR2007/006413
Other languages
French (fr)
Other versions
WO2008078883A9 (en
Inventor
Ki Ju Kang
Chang Jun Lee
Dong Seok Lee
Byung Cheol Lee
Original Assignee
Industry Foundation Of Chonnam National University
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Publication date
Application filed by Industry Foundation Of Chonnam National University filed Critical Industry Foundation Of Chonnam National University
Publication of WO2008078883A1 publication Critical patent/WO2008078883A1/en
Publication of WO2008078883A9 publication Critical patent/WO2008078883A9/en

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
    • E04C2/30—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure
    • E04C2/34—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D13/00—Corrugating sheet metal, rods or profiles; Bending sheet metal, rods or profiles into wave form
    • B21D13/10—Corrugating sheet metal, rods or profiles; Bending sheet metal, rods or profiles into wave form into a peculiar profiling shape
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21F—WORKING OR PROCESSING OF METAL WIRE
    • B21F27/00—Making wire network, i.e. wire nets
    • B21F27/12—Making special types or portions of network by methods or means specially adapted therefor
    • B21F27/128—Making special types or portions of network by methods or means specially adapted therefor of three-dimensional form by connecting wire networks, e.g. by projecting wires through an insulating layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
    • E04C2/02—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials
    • E04C2/26—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by specified materials composed of materials covered by two or more of groups E04C2/04, E04C2/08, E04C2/10 or of materials covered by one of these groups with a material not specified in one of the groups
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
    • E04C2/30—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure
    • E04C2/34—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts
    • E04C2/3405—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts spaced apart by profiled spacer sheets
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C2/00—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels
    • E04C2/30—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure
    • E04C2/34—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts
    • E04C2002/3488—Building elements of relatively thin form for the construction of parts of buildings, e.g. sheet materials, slabs, or panels characterised by the shape or structure composed of two or more spaced sheet-like parts spaced apart by frame like structures

Definitions

  • the present invention relates to a lightweight sandwich panel with a core composed of wires and a manufacturing method thereof.
  • sandwich panel structures include upper and lower face sheets made of a material having a high strength/density and a core made of a porous material having a low density, such as Styrofoam, or a lattice-shaped material .
  • FIG.1 is a perspective view i 1 lustrat ing several conventional sandwich panel structures, each of which has a lattice-shaped core. Most lattice-shaped cores or porous materials include several closed chambers formed therein, and thus cause a difficulty in space utilization.
  • a truss structure designed to have the optimum strength through precise calculation is advantageous in that the truss structure has mechanical properties almost similar to those of a honeycomb lattice structure, and the inside of the truss structure is opened and thus the internal space of the truss structure can be used.
  • the most general truss structure is a pyramid truss.
  • the pyramid truss is configured such that four regular triangular lattices form inclined planes and a regular tetragonal lattice forms a lower (or upper) plane, and thus has an advantage of forming a rectangular plate structure.
  • another truss structure i.e., an Octet truss, in which regular tetrahedrons and regular octahedrons are mixed, (R. Buckminster Fuller, 1961, US Patent 2,986,241).
  • respective elements of the truss structure form an equilateral triangle.
  • FIGs. 2, 3, and 4 illustrate sandwich panels obtained by attaching face sheets to upper and lower surfaces of cores respectively having a pyramid, Octet, and Kagome truss structures.
  • the Octet and Kagome truss are slightly superior in compressive strength to weight to the pyramid truss when compressive or tensile load is applied to the trusses.
  • shearing load is applied to a truss
  • a variation in strength of the truss according to direction is severe.
  • lateral load such as three-point bending
  • the first method is that an entire structure including a truss core is made of a resin and then a metal is cast using the structure as a mold.
  • the first method is disadvantageous in that this method requires high production costs, is limited to a metal having an excellent castability, and easily causes defects.
  • the second method is that a truss core is made by forming periodic rectangular holes through a thin plate so as to produce the plate in a mesh shape and bending the plate in a V shape along diagonal lines, and then face sheets are respectively attached to the upper and lower surface of the core. This method generates a material loss during a process for punching the plate.
  • the third method is that a metal plate in a mesh shape is made by an expanded metal process instead of punching.
  • the fourth method is that a core having a pyramid truss structure is formed by bending a wire mesh, obtained by interweaving wires in orthogonal two direct ions, along diagonal lines of crossing points so as to form V-shaped prominences and depressions, and face sheets are respectively attached to the upper and lower surfaces of the core.
  • the second, third and fourth methods are basically the same in that a mesh shape with rectangular holes is fabricated first and then is bent to form a core.
  • FIGs. 5 and 6 illustrate the third method
  • FIG. 7 illustrates the fourth method. It was known that these two methods minimize production costs, but the methods are disadvantageous in that the methods are limited to a material having an excellent formability and cannot use thick wires due to interference generated by the crossing of the wires at apexes of trusses.
  • U.S. Patent No. 6,644,535 B2 J.C. Wallach and L.J. Gibson discloses a method for fabricating a structure similar to a pyramid truss by bending wires into a triangular wave shape and interweaving the wires with each other in orthogonal two directions.
  • FIG. 8 illustrates this structure.
  • Wires as a raw material for forming a truss have advantageous, as follows.
  • WO 2005/044483 discloses a method for fabricating a truss structure similar to a Kagome truss by three-dimensional Iy interweaving wires in six directions.
  • FIG. 10 illustrates this structure.
  • the above-described truss structure fabrication methods using wires have the common problem, i.e. , interference between wires due to the interweaving or overlapping of the wires.
  • the obtained truss structures differ from the ideal truss structure, which is originally desired, or wires corresponding to straight elements of the ideal truss structures, i.e., struts, are deflected.
  • the present invention has been made in view of the above problems, and it is an object of the present invention to provide a lightweight sandwich panel having a truss core using wires as a raw material, which has a structure of completely removing interference between the wires, is easily mass produced, and has a mechanical performance similar to that of a conventional truss structure, and a manufacturing method thereof.
  • a sandwich panel comprising upper and lower face sheets and a truss core, wherein in a space expressed by the ⁇ -axis and the z-axis, being on the same plane and crossing perpendicularly, and the y-axis being perpendicular to the plane, the upper and lower face sheets are parallel with the ⁇ -z plane, and the truss core having wires formed in a triangular wave shape, such that the wires have the triangular wave shape when the truss core is projected on a plane being perpendicular to the z-axis and have directions alternately changed per two sides of a unit structure of the triangular wave shape when the truss core is projected on a plane being perpendicular to the y-axis, is interposed between the upper and lower face sheets.
  • the sandwich panel according to (1) wherein the wires are disposed in parallel on the ⁇ -z plane at regular intervals.
  • the lightweight sandwich panel of the present invention has advantages, as follows.
  • the lightweight sandwich panel uses wires, which are easily manufactured, have few defects, achieve a high strength, and are easily processed, as a material for a core.
  • the lightweight sandwich panel has a structure, which can completely remove interference between the wires, and thus has a configuration using thick wires without deflecting as truss elements or having truss elements having a low slenderness ratio, thereby obtaining a high-strength structure.
  • the lightweight sandwich panel obtains a desired mechanical performance by adjusting the bending angle, disposition intervals, and disposition method of the wire structure.
  • the lightweight sandwich panel obtains the wire structure of the core only by two simple bending processes without any complicated process, such as interweaving of the wires, thus reducing production costs and being easily mass-produced.
  • FIG. 1 is a perspective view i 1 lustrat ing various conventional sandwich panel structures
  • FIGs.2 to 4 are perspective views i 1 lustrat ing sandwich panels, each of which is obtained by attaching face sheets to upper and lower surfaces of a core composed of a pyramid, Octet, or Kagome truss structure;
  • FIG.5 is a schematic view illustrating a conventional method for manufacturing a pyramid truss by bending an expanded metal mesh
  • FIG.6 is a schematic view illustrating a conventional method for manufacturing a pyramid truss by forming an expanded metal mesh by shearing/expanding a plate and then bending the expanded metal mesh
  • FIG.7 is a schematic view illustrating a conventional method for manufacturing a pyramid truss by bending a woven wire mesh
  • FIG.8 is a schematic view illustrating a conventional method for manufacturing a structure similar to a pyramid truss by interweaving wires, bent in a triangular wave shape, in orthogonal two directions;
  • FIG.9 is a schematic view illustrating a conventional method for manufacturing an Octet truss by interweaving wires, bent in a triangular wave shape, in three directions;
  • FIG.10 is a schematic view illustrating a conventional method for manufacturing a three-dimensional truss structure similar to a Kagome truss by interweaving wires in six directions!
  • FIG. 11 is a perspective view of a lightweight sandwich panel in accordance with a preferred embodiment of the present invention with the upper face sheet removed;
  • FIG. 12 shows plan, front, and right side views illustrating the shape and disposition of wires of a core of the lightweight sandwich panel of FIG. 11;
  • FIG. 13 shows views comparing a unit structure of the wires in a triangular wave shape of FIG. 12 to a pyramid truss;
  • FIG. 14 shows perspective and plan views of a core formed by alternately disposing the wires of FIG. 12;
  • FIG. 15 shows perspective and plan views of a core composed of a complete pyramid truss including truss elements having the same wire diameter and length as those of FIG. 14;
  • FIG. 16 shows perspective views of cores, in which intervals between wires are adjusted, in accordance with various embodiments of the present invention
  • FIG. 17 shows perspective and plan views of a core, in which wires bent in a triangular wave shape are disposed in parallel such that intervals between the wires are not regular but are varied;
  • FIG. 18 shows perspective and plan views of a core, in which wires bent in a triangular wave shape and having two azimuths are alternately disposed on the x-z plane;
  • FIG. 19 shows perspective and plan views of a core, in which wires bent in a triangular wave shape are radially disposed on the ⁇ -z plane;
  • FIG.20 is a view il lustrating a process for first bending wires so as to form a core of a lightweight panel in accordance with the present invention.
  • FIG.21 is a view illustrating a process for second bending the first-bent wires of FIG. 20.
  • FIG. 11 is a perspective view of a lightweight sandwich panel in accordance with the present invention.
  • FIG. 12 shows plan, front, and right side views illustrating the shape and disposition of wires 1 forming a core of the lightweight sandwich panel of FIG. 11.
  • the wires 1 bent in orthogonal two directions into a triangular wave shape are disposed on the x-z plane at regular intervals, thus forming a truss.
  • FIG. 13 compares a unit structure 2 of wires in a triangular wave shape of FIG. 12, i.e., a unit structure 2, in which two triangular forms, each including two truss elements, are connected in a zigzag shape seen from the y-axis, to a pyramid truss 3. It is understood that when one part of the unit structure 2 of FIG. 13(a) is parallel shifted with respect to the central line so as to be overlapped with the other part of the unit structure 2, the obtained structure is equal to the pyramid truss of FIG. 13(b).
  • FIG.14 shows perspective and plan views of a structure 4 formed by alternately disposing the wires of FIG.12.
  • contact points of a wire with the lower face sheet and contact points of the front or rear wire with the lower face sheet meet.
  • the contact points of the wires with the lower face sheet are configured such that four truss elements are met at the contact points in the same manner as the pyramid truss.
  • FIG.15 illustrates a complete pyramid truss 5 including truss elements having the same wire diameter and length, as those of FIG. 14.
  • the structure of FIG. 14 is a part of the complete pyramid truss 5 of FIG. 15. That is, when two structures of FIG. 14 are overlapped with each other, the complete pyramid truss 5 is obtained.
  • the structure of FIG.14 under the condition that the relative positions of the apexes of the structure are fixed by joining with upper and lower face sheets, has density, strength, and stiffness, which are half those of the pyramid truss.
  • FIG. 16 shows perspective views of structures, in which intervals between wires of the core are adjusted in three ways.
  • the intervals between the wires of a structure are half the intervals between the wires of FIG. 14, the structure has density, strength, and stiffness equal to those of the complete pyramid truss.
  • the intervals between the contact points of the structure with the upper and lower face sheets are half the intervals between the contact points of the pyramid truss with the upper and lower face sheets, when bending load is applied to the sandwich panel, the strength of the face sheets against buckling are increased.
  • the lightweight sandwich panel obtains a desired mechanical performance by adjusting the bending angle, disposition intervals, and disposition method of the wires of the core.
  • the sandwich panel it is possible to apply the sandwich panel to various fields by changing the constitution of the core, in consideration of load conditions together with the size, shape, and purpose of the panel.
  • the intervals between a plural ity of wires 1 disposed in paral IeI other are varied, as shown in FIG. 17, and thus the wires 1 form a core of the sandwich panel.
  • FIG.18 i llustrates an embodiment , in which a wire having a different azimuth is interposed between wires 1 disposed in parallel. Consequently, a core of the sandwich panel of FIG. 18 includes a plurality of wires oriented in two directions.
  • the wires 1 may be radially disposed.
  • FIG. 19 illustrates an embodiment, in which the wires 1 are radially disposed.
  • the most important advantage of the wire structure of the core of the sandwich panel of the present invention is that contacts between wires can be minimized or completely removed and thus it is possible to form a truss without interference between the wires regardless of the thickness of the wires. Accordingly, the sandwich panel is easily manufactured and has an excellent mechanical performance.
  • the vacant space in the core of the sandwich panel may be filled with one selected from the group consisting of a porous material, resin, metal, and ceramic, thereby improving the insulating capacity, noise and vibration suppression capacity, and other mechanical properties of the panel and providing other functions to the panel.
  • a method for manufacturing a sandwich panel having a core composed of wires in accordance with the present invention wi 11 be described.
  • FIGs.20 and 21 i llustrate the bending of the wires.
  • the wires are bent into a triangular wave shape in-plane, as shown in FIG.
  • FIG.21 illustrates a process for second bending the first-bent wires of FIG.20 laid on a horizontal plane. That is, the first-bent wires between V-shaped molds 6 and 8 are bent in a zigzag shape using a press out-of-plane repeatedly in regular and reverse directions at intervals of two sides of the first-bent wires.
  • the bent wires 9 are located between thin upper and lower face sheets and thus form a core.
  • contact points of the wires 9 with the upper and lower face sheets are respectively connected to the upper and lower face sheets by welding, brazing, or resin-bonding. Thereby, the manufacture of the sandwich panel of the present invention is completed.

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Abstract

Disclosed are a lightweight sandwich panel with a core composed of wires and a manufacturing method thereof. The lightweight sandwich panel includes upper and lower face sheets, and a truss core. The truss core is formed by bending wires. That is, the wires, bent inorthogonal two directions into a triangular wave shape, are disposed at regular intervals on a plane, and thus form a truss. The truss may have the same mechanical performance and shape as those of a conventional pyramid truss by adjusting the bending angle, disposition intervals, and disposition method of the wires. Since contacts between the wires are minimized or completely removed, it is possible to form a truss without interference between the wires regardless of the thickness of the wires. Thus, the sandwich panel is easi Iy manufactured and has an excellent mechanical performance.

Description

[DESCRIPTION] [Invention Title]
A LIGHT WEIGHT SANDWICH PANEL WITH A CORE CONSTRUCTED OF WIRES AND THE MANUFACTURING METHOD OF THE SAME
[Technical Field]
The present invention relates to a lightweight sandwich panel with a core composed of wires and a manufacturing method thereof.
[Background Art]
Generally, sandwich panel structures include upper and lower face sheets made of a material having a high strength/density and a core made of a porous material having a low density, such as Styrofoam, or a lattice-shaped material . FIG.1 is a perspective view i 1 lustrat ing several conventional sandwich panel structures, each of which has a lattice-shaped core. Most lattice-shaped cores or porous materials include several closed chambers formed therein, and thus cause a difficulty in space utilization.
Recently, a periodic truss structure as a novel material for a core has been introduced (H.N.G. Wadley, N.A. Fleck, A.G. Evans, 2003,
Composite Science and Technology, Vol.63, pp.2331-2343). A truss structure designed to have the optimum strength through precise calculation is advantageous in that the truss structure has mechanical properties almost similar to those of a honeycomb lattice structure, and the inside of the truss structure is opened and thus the internal space of the truss structure can be used.
The most general truss structure is a pyramid truss. The pyramid truss is configured such that four regular triangular lattices form inclined planes and a regular tetragonal lattice forms a lower (or upper) plane, and thus has an advantage of forming a rectangular plate structure. Further, there is another truss structure, i.e., an Octet truss, in which regular tetrahedrons and regular octahedrons are mixed, (R. Buckminster Fuller, 1961, US Patent 2,986,241). In this structure, respective elements of the truss structure form an equilateral triangle. In the twenty first century, a Kagome truss, which is transformed from the Octet truss, has been developed (S. Hyun, A.M. Karlsson, S. Torquato, A.G. Evans, 2003, Int J. of Solids and structures, Vol.40, pp.6989-6998).
FIGs. 2, 3, and 4 illustrate sandwich panels obtained by attaching face sheets to upper and lower surfaces of cores respectively having a pyramid, Octet, and Kagome truss structures. It was known that the Octet and Kagome truss are slightly superior in compressive strength to weight to the pyramid truss when compressive or tensile load is applied to the trusses. However, in the case that shearing load is applied to a truss, a variation in strength of the truss according to direction is severe. Thus, when lateral load, such as three-point bending, is applied to a sandwich panel, a truss having a low variation in shearing strength according to direction, such as a pyramid truss, is favorable. In order to manufacture a sandwich panel having a pyramid truss core, several methods can be used, as follows. (H.H.G. Wadley, etc., 2003, "Fabrication and structural performance of periodic cellular metal sandwich structure" , Composite Science Technology, Vol.63, pp.2331-2343).
The first method is that an entire structure including a truss core is made of a resin and then a metal is cast using the structure as a mold. The first method is disadvantageous in that this method requires high production costs, is limited to a metal having an excellent castability, and easily causes defects.
The second method is that a truss core is made by forming periodic rectangular holes through a thin plate so as to produce the plate in a mesh shape and bending the plate in a V shape along diagonal lines, and then face sheets are respectively attached to the upper and lower surface of the core. This method generates a material loss during a process for punching the plate.
In order to remove the material loss of the second method, the third method is that a metal plate in a mesh shape is made by an expanded metal process instead of punching.
The fourth method is that a core having a pyramid truss structure is formed by bending a wire mesh, obtained by interweaving wires in orthogonal two direct ions, along diagonal lines of crossing points so as to form V-shaped prominences and depressions, and face sheets are respectively attached to the upper and lower surfaces of the core. The second, third and fourth methods are basically the same in that a mesh shape with rectangular holes is fabricated first and then is bent to form a core.
FIGs. 5 and 6 illustrate the third method, and FIG. 7 illustrates the fourth method. It was known that these two methods minimize production costs, but the methods are disadvantageous in that the methods are limited to a material having an excellent formability and cannot use thick wires due to interference generated by the crossing of the wires at apexes of trusses.
U.S. Patent No. 6,644,535 B2 (J.C. Wallach and L.J. Gibson) discloses a method for fabricating a structure similar to a pyramid truss by bending wires into a triangular wave shape and interweaving the wires with each other in orthogonal two directions. FIG. 8 illustrates this structure.
Wires as a raw material for forming a truss have advantageous, as follows.
First, wires are easily manufactured and have few defects. Second, the strength of wires can be increased through work hardening, or high strength materials such as piano wires can be easi Iy obtained. Third, wires easily undergo plastic working, such as bending. Accordingly, methods for manufacturing a periodical truss structure by using wires have recently been proposed. KoreanPatent Application No.2004-0105226 (K.J. Kang, S.J. Na, B.K. Kim, D.G. Ann, and Y.J. Jo, 2004, Method for manufacturing lightweight sandwich panels) discloses a method for fabricating an Octet truss by interweaving wires, bent in a triangular wave shape, in three directions. FIG. 9 illustrates this structure. PCT Publication No. WO 2005/044483 (K.J. Kang and Y.H. Lee, 2004) discloses a method for fabricating a truss structure similar to a Kagome truss by three-dimensional Iy interweaving wires in six directions. FIG. 10 illustrates this structure.
The above-described truss structure fabrication methods using wires have the common problem, i.e. , interference between wires due to the interweaving or overlapping of the wires. Thus, the obtained truss structures differ from the ideal truss structure, which is originally desired, or wires corresponding to straight elements of the ideal truss structures, i.e., struts, are deflected. The thicker the wires are, the severer the interference between the wires becomes, and thus it is difficult to use the wires as a structural material requiring a high strength.
[Disclosure]
[Technical Problem]
Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a lightweight sandwich panel having a truss core using wires as a raw material, which has a structure of completely removing interference between the wires, is easily mass produced, and has a mechanical performance similar to that of a conventional truss structure, and a manufacturing method thereof.
[Technical Solution]
The features of the present invention for attaining the aforementioned objects are as follows.
(1) A sandwich panel comprising upper and lower face sheets and a truss core, wherein in a space expressed by the χ-axis and the z-axis, being on the same plane and crossing perpendicularly, and the y-axis being perpendicular to the plane, the upper and lower face sheets are parallel with the χ-z plane, and the truss core having wires formed in a triangular wave shape, such that the wires have the triangular wave shape when the truss core is projected on a plane being perpendicular to the z-axis and have directions alternately changed per two sides of a unit structure of the triangular wave shape when the truss core is projected on a plane being perpendicular to the y-axis, is interposed between the upper and lower face sheets. (2) The sandwich panel according to (1), wherein the wires are disposed in parallel on the χ-z plane at regular intervals.
(3) The sandwich panel according to (2), wherein the wires are repeatedly overturned or alternately disposed.
(4) The sandwich panel according to (2), wherein wires are interposed between the wires disposed in parallel such that the interposed wires are inclined to the wires disposed in parallel.
(5) The sandwich panel according to (1), wherein the wires may be disposed in parallel on the x-z plane at varied intervals.
(6) The sandwich panel according to (1), wherein the wires may be radially disposed on the χ-z plane.
(7) The sandwich panel according to any one of (1) to (6), wherein the space in the core may be filled with one selected from the group consisting of a porous material , resin, metal, and ceramic.
(8) A method for manufacturing the sandwich panel according to any one of (1) to (6), comprising: first bending wires in-plane into a triangular wave shape; second bending the first-bent wires out-of-plane repeatedly in regular and reverse directions at intervals of two sides of the first-bent wires arraying the second-bent wires on a lower face sheet so as to form a core! and laying an upper face sheet on the core arranged on the lower face sheet, and connecting contacts points, of the core with the upper and lower face sheets, to the upper and lower face sheets. [Advantageous Effects]
As described above, the lightweight sandwich panel of the present invention has advantages, as follows.
First, the lightweight sandwich panel uses wires, which are easily manufactured, have few defects, achieve a high strength, and are easily processed, as a material for a core.
Second, the lightweight sandwich panel has a structure, which can completely remove interference between the wires, and thus has a configuration using thick wires without deflecting as truss elements or having truss elements having a low slenderness ratio, thereby obtaining a high-strength structure.
Third, the lightweight sandwich panel obtains a desired mechanical performance by adjusting the bending angle, disposition intervals, and disposition method of the wire structure. Fourth, the lightweight sandwich panel obtains the wire structure of the core only by two simple bending processes without any complicated process, such as interweaving of the wires, thus reducing production costs and being easily mass-produced.
[Description of Drawings]
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 is a perspective view i 1 lustrat ing various conventional sandwich panel structures;
FIGs.2 to 4 are perspective views i 1 lustrat ing sandwich panels, each of which is obtained by attaching face sheets to upper and lower surfaces of a core composed of a pyramid, Octet, or Kagome truss structure;
FIG.5 is a schematic view illustrating a conventional method for manufacturing a pyramid truss by bending an expanded metal mesh;
FIG.6 is a schematic view illustrating a conventional method for manufacturing a pyramid truss by forming an expanded metal mesh by shearing/expanding a plate and then bending the expanded metal mesh; FIG.7 is a schematic view illustrating a conventional method for manufacturing a pyramid truss by bending a woven wire mesh;
FIG.8 is a schematic view illustrating a conventional method for manufacturing a structure similar to a pyramid truss by interweaving wires, bent in a triangular wave shape, in orthogonal two directions;
FIG.9 is a schematic view illustrating a conventional method for manufacturing an Octet truss by interweaving wires, bent in a triangular wave shape, in three directions;
FIG.10 is a schematic view illustrating a conventional method for manufacturing a three-dimensional truss structure similar to a Kagome truss by interweaving wires in six directions!
FIG. 11 is a perspective view of a lightweight sandwich panel in accordance with a preferred embodiment of the present invention with the upper face sheet removed; FIG. 12 shows plan, front, and right side views illustrating the shape and disposition of wires of a core of the lightweight sandwich panel of FIG. 11;
FIG. 13 shows views comparing a unit structure of the wires in a triangular wave shape of FIG. 12 to a pyramid truss;
FIG. 14 shows perspective and plan views of a core formed by alternately disposing the wires of FIG. 12;
FIG. 15 shows perspective and plan views of a core composed of a complete pyramid truss including truss elements having the same wire diameter and length as those of FIG. 14;
FIG. 16 shows perspective views of cores, in which intervals between wires are adjusted, in accordance with various embodiments of the present invention; FIG. 17 shows perspective and plan views of a core, in which wires bent in a triangular wave shape are disposed in parallel such that intervals between the wires are not regular but are varied;
FIG. 18 shows perspective and plan views of a core, in which wires bent in a triangular wave shape and having two azimuths are alternately disposed on the x-z plane;
FIG. 19 shows perspective and plan views of a core, in which wires bent in a triangular wave shape are radially disposed on the χ-z plane;
FIG.20 is a view il lustrating a process for first bending wires so as to form a core of a lightweight panel in accordance with the present invention; and
FIG.21 is a view illustrating a process for second bending the first-bent wires of FIG. 20.
[Mode for Invention]
Now, preferred embodiments of the present invention will be described in detail with reference to the annexed drawings.
FIG. 11 is a perspective view of a lightweight sandwich panel in accordance with the present invention.
FIG. 12 shows plan, front, and right side views illustrating the shape and disposition of wires 1 forming a core of the lightweight sandwich panel of FIG. 11. The wires 1 bent in orthogonal two directions into a triangular wave shape are disposed on the x-z plane at regular intervals, thus forming a truss.
FIG. 13 compares a unit structure 2 of wires in a triangular wave shape of FIG. 12, i.e., a unit structure 2, in which two triangular forms, each including two truss elements, are connected in a zigzag shape seen from the y-axis, to a pyramid truss 3. It is understood that when one part of the unit structure 2 of FIG. 13(a) is parallel shifted with respect to the central line so as to be overlapped with the other part of the unit structure 2, the obtained structure is equal to the pyramid truss of FIG. 13(b). Since the apexes of two triangular structures of a pyramid truss coincide with each other, four truss elements of the pyramid truss support one another and thus the pyramid truss is stable. On the other hand, since the right and left apexes of the unit structure of the present invention are separated from each other, the right and left parts do not support each other and thus the unit structure of the present invention is unstable. However, the unit structure of the present invention forms a core between upper and lower face sheets such that the apexes of the unit structure are attached to the upper and lower face sheets, thus becoming stable. FIG.14 shows perspective and plan views of a structure 4 formed by alternately disposing the wires of FIG.12. That is, contact points of a wire with the lower face sheet and contact points of the front or rear wire with the lower face sheet meet. The contact points of the wires with the lower face sheet are configured such that four truss elements are met at the contact points in the same manner as the pyramid truss.
FIG.15 illustrates a complete pyramid truss 5 including truss elements having the same wire diameter and length, as those of FIG. 14. In the comparison of FIG.14 and FIG. 15, it is understood that the structure of FIG. 14 is a part of the complete pyramid truss 5 of FIG. 15. That is, when two structures of FIG. 14 are overlapped with each other, the complete pyramid truss 5 is obtained. Theoretically, the structure of FIG.14, under the condition that the relative positions of the apexes of the structure are fixed by joining with upper and lower face sheets, has density, strength, and stiffness, which are half those of the pyramid truss.
FIG. 16 shows perspective views of structures, in which intervals between wires of the core are adjusted in three ways. When the intervals between the wires of a structure are half the intervals between the wires of FIG. 14, the structure has density, strength, and stiffness equal to those of the complete pyramid truss. Further, since the intervals between the contact points of the structure with the upper and lower face sheets are half the intervals between the contact points of the pyramid truss with the upper and lower face sheets, when bending load is applied to the sandwich panel, the strength of the face sheets against buckling are increased. As described above, the lightweight sandwich panel obtains a desired mechanical performance by adjusting the bending angle, disposition intervals, and disposition method of the wires of the core.
Accordingly, it is possible to apply the sandwich panel to various fields by changing the constitution of the core, in consideration of load conditions together with the size, shape, and purpose of the panel. For example, in the case that the applied load is unevenly distributed on the sandwich panel, the intervals between a plural ity of wires 1 disposed in paral IeI other are varied, as shown in FIG. 17, and thus the wires 1 form a core of the sandwich panel.
Further, in addition to the parallel disposition of the wires of the core, it is possible to control the mechanical properties of the sandwich panel by adjusting angles between the wires.
For example, FIG.18 i llustrates an embodiment , in which a wire having a different azimuth is interposed between wires 1 disposed in parallel. Consequently, a core of the sandwich panel of FIG. 18 includes a plurality of wires oriented in two directions.
Particularly, in the case that the sandwich panel has axisymmetric shape with respect to an axis or the shape of a portion of a circle, the wires 1 may be radially disposed. FIG. 19 illustrates an embodiment, in which the wires 1 are radially disposed.
The most important advantage of the wire structure of the core of the sandwich panel of the present invention is that contacts between wires can be minimized or completely removed and thus it is possible to form a truss without interference between the wires regardless of the thickness of the wires. Accordingly, the sandwich panel is easily manufactured and has an excellent mechanical performance.
According to the preferred embodiment of the present invention, the vacant space in the core of the sandwich panel may be filled with one selected from the group consisting of a porous material, resin, metal, and ceramic, thereby improving the insulating capacity, noise and vibration suppression capacity, and other mechanical properties of the panel and providing other functions to the panel. Hereinafter, a method for manufacturing a sandwich panel having a core composed of wires in accordance with the present invention wi 11 be described.
FIGs.20 and 21 i llustrate the bending of the wires. First , the wires are bent into a triangular wave shape in-plane, as shown in FIG.
20. FIG.21 illustrates a process for second bending the first-bent wires of FIG.20 laid on a horizontal plane. That is, the first-bent wires between V-shaped molds 6 and 8 are bent in a zigzag shape using a press out-of-plane repeatedly in regular and reverse directions at intervals of two sides of the first-bent wires.
Then, the bent wires 9 are located between thin upper and lower face sheets and thus form a core. Here, contact points of the wires 9 with the upper and lower face sheets are respectively connected to the upper and lower face sheets by welding, brazing, or resin-bonding. Thereby, the manufacture of the sandwich panel of the present invention is completed.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[CLAIMS] [Claim 1]
A sandwich panel comprising upper and lower face sheets and a truss core, wherein in a space expressed by the χ-axis and the z-axis, being on the same plane and crossing perpendicularly, and the y-axis being perpendicular to the plane, the upper and lower face sheets are parallel with the x-z plane, and the truss core having wires formed in a triangular wave shape, such that the wires have the triangular wave shape when the truss core is projected on a plane being perpendicular to the z-axis and have directions alternately changed per two sides of a unit structure of the triangular wave shape when the truss core is projected on a plane being perpendicular to the y-axis, is interposed between the upper and lower face sheets.
[Claim 2]
The sandwich panel according to claim 1, wherein the wires are disposed in parallel on the χ-z plane at regular intervals.
[Claim 3] The sandwich panel according to claim 2, wherein the wires are repeatedly overturned or alternately disposed.
[Claim 4]
The sandwich panel according to claim 2, wherein wires are interposed between the wires disposed in parallel such that the interposed wires are inclined to the wires disposed in parallel.
[Claim 5]
The sandwich panel according to claim 1, wherein the wires are disposed in parallel on the x-z plane at varied intervals.
[Claim 6]
The sandwich panel according to claim 1, wherein the wires are radially disposed on the χ-z plane.
[Claim 7]
The sandwich panel according to any one of claims 1 to 6, wherein the space in the core is filled with one selected from the group consisting of a porous material, resin, metal, and ceramic.
[Claim 8]
A method for manufacturing the sandwich panel according to any one of claims 1 to 6, comprising-' first bending wires in-plane into a triangular wave shape; second bending the first-bent wires out-of-plane repeatedly in regular and reverse directions at intervals of two sides of the first-bent wires! arraying the second-bent wires on a lower face sheet so as to form a core! and laying an upper face sheet on the core arranged on the lower face sheet , and connecting contacts points, of the core with the upper and lower face sheets, to the upper and lower face sheets.
PCT/KR2007/006413 2006-12-22 2007-12-10 A light weight sandwich panel with a core constructed of wires and the manufacturing method of the same WO2008078883A1 (en)

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WO2017034553A1 (en) 2015-08-25 2017-03-02 Hrl Laboratories, Llc Sparse truss structures and methods of making the same
CN113814327A (en) * 2020-06-19 2021-12-21 贵州理工学院 Manufacturing method of tetrahedral metal micro-truss sandwich structure and stamping die thereof
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101057946B1 (en) * 2008-07-25 2011-08-18 전남대학교산학협력단 Truss type periodic porous material filled with some of the cells inside
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KR101049658B1 (en) 2008-09-17 2011-07-14 전남대학교산학협력단 Zigzag truss structure and sandwich plate including the same
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KR101158088B1 (en) * 2010-07-16 2012-06-22 한국과학기술원 Polyhedron truss structure by using a sheet metal
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6644535B2 (en) * 2001-05-18 2003-11-11 Massachusetts Institute Of Technology Truss core sandwich panels and methods for making same
WO2005044483A1 (en) * 2003-11-07 2005-05-19 Ki Ju Kang Three-dimensional cellular light structures directly woven by continuous wires and the manufacturing method of the same
KR20060066766A (en) * 2004-12-14 2006-06-19 현대자동차주식회사 Method to manufacture light sandwich panels

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AR204992A1 (en) 1973-06-13 1976-03-31 Rheinische Filigranbau Gmbh Co CELOSIA BEAMS FOR CONCRETE ARMOR PROCEDURE AND APPARATUS FOR THEIR MANUFACTURE
JPS57155458A (en) 1981-03-20 1982-09-25 Takenaka Komuten Co Assembled truss skeletal
CH653080A5 (en) 1983-05-27 1985-12-13 Beaumond Jean J THREE-DIMENSIONAL METAL FRAMEWORK FOR CONSTRUCTION PANELS.
KR100589617B1 (en) * 2004-04-14 2006-06-19 한국과학기술원 Variable sandwich panel using metal wire
KR100700212B1 (en) * 2004-12-14 2007-03-27 전남대학교산학협력단 Assembly of coil springs and sandwich panel using the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6644535B2 (en) * 2001-05-18 2003-11-11 Massachusetts Institute Of Technology Truss core sandwich panels and methods for making same
WO2005044483A1 (en) * 2003-11-07 2005-05-19 Ki Ju Kang Three-dimensional cellular light structures directly woven by continuous wires and the manufacturing method of the same
KR20060066766A (en) * 2004-12-14 2006-06-19 현대자동차주식회사 Method to manufacture light sandwich panels

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013230593A (en) * 2012-04-27 2013-11-14 Nippon Steel & Sumitomo Metal Corp Laminated steel plate
EP2824251A3 (en) * 2013-07-11 2015-02-25 Korea Advanced Institute Of Science And Technology Pyramidal kagome structure and its fabricating method
WO2017034553A1 (en) 2015-08-25 2017-03-02 Hrl Laboratories, Llc Sparse truss structures and methods of making the same
CN108137309A (en) * 2015-08-25 2018-06-08 Hrl实验室有限责任公司 Sparse truss structure and its manufacturing method
EP3341322A4 (en) * 2015-08-25 2019-05-08 HRL Laboratories LLC Sparse truss structures and methods of making the same
CN113814327A (en) * 2020-06-19 2021-12-21 贵州理工学院 Manufacturing method of tetrahedral metal micro-truss sandwich structure and stamping die thereof
CN115556437A (en) * 2022-10-08 2023-01-03 上海兰钧新能源科技有限公司 Bottom protection plate for battery pack and battery pack

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