KR102079564B1 - Laminate grid panel structure and fabrication method therefore - Google Patents

Abstract

The present invention relates to a laminated lattice panel and a method for manufacturing the same, and more particularly, to a light and high rigid laminated lattice panel and a method for manufacturing the same that can be used as a lower support structure for the arrangement of the tile antenna.

Description

Laminated grid panel structure and fabrication method therefore

The present invention relates to a laminated lattice panel and a method for manufacturing the same, and more particularly, to a light and high rigid laminated lattice panel and a method for manufacturing the same that can be used as a lower support structure for the arrangement of the tile antenna.

Composite materials are being studied or applied in various industries requiring high weight due to high specific stiffness and specific strength, and various structural design methods have emerged in order to obtain higher rigidity with the same material. It was.

Representative composite structure design methods include sandwich structure and grid / lattice structure. The sandwich structure is a symmetrical structure in which the outermost layer is laminated with a composite material and a low density honeycomb core or a foam core is placed in the middle, and the thickness of the structure is increased to give high stiffness characteristics. .

In addition, the grating structure refers to a lightweight rigid structure to which various grating patterns are applied. Stiffness in the out-of-plane direction is weaker than sandwich structure of the same weight, but stiffness in the in-plane direction is excellent. In addition, it is easier to inspect due to damage than the sandwich structure, and corrosion of the core material due to moisture penetration during the manufacturing process or long-term operation is not concerned. Because of these advantages, it is being widely used in the space industry.

A typical method of manufacturing the composite lattice structure is the filament winding method. Structures manufactured in this form are mainly applied to projectile structures that must withstand high loads. Since this method is manufactured in the form of a cylinder, the shape that can be applied is limited, and the fiber volume fraction of the intersection portion and the non-contrast portion of the fiber is different in the manufacturing process. It takes time and effort.

Meanwhile, Tsai et al. Studied the interlocked lattice structure and confirmed its structural excellence. However, it is pointed out that by separately manufacturing the grating, a structure and a separate bonding process are required, and a large stress concentration occurs in the slot by performing slot processing to cross the grating.

Prior Document: Korean Patent Registration No. 10-1343912 "Grid-reinforced lightweight composite electronics housing for space mission applications"

The present invention is to solve the above-mentioned problems, an object of the present invention is to cut the fabric type fiber-reinforced composite material in a grid pattern in a prepreg (Prepreg) state, the production of a laminated grid panel laminated and molded integrally The purpose is to provide a method.

In addition, the present invention by freely setting the interval and thickness between the gratings for the grid structure, it is possible to apply variously depending on the intention of the structure or designer to which the grating panel is applied, with respect to the direction (outward or inward) of the grating An object of the present invention is to provide a method of manufacturing a laminated lattice panel which can be freely arranged and has high design freedom.

In addition, an object of the present invention is to provide a manufacturing method of a laminated grid panel capable of manufacturing a grid panel having a three-dimensional curved shape instead of a conventional flat grid panel panel, which can actively correspond to the shape of the application target. .

In order to solve the above-described problem, the manufacturing method of the laminated lattice panel according to the present invention is a manufacturing method of the lattice panel, the lattice pattern lamination groove 110 is provided on the surface, a plurality of blocks partitioned by the lamination groove Mold manufacturing step (S100) for producing a mold 100 is formed 120; A preliminary step (S200) of preparing a prepreg 200 by pre-impregnating a raw material for laminating in the mold in a resin; A cutting step (S300) of cutting the prepreg into a lattice pattern so as to correspond to a shape of a stack groove of the mold to produce a lattice type prepreg (300); A first stacking step (S400) of stacking the lattice type prepreg into the stack groove of the mold; Stacking the prepreg on top of the lattice prepreg (S500); And forming the laminated lattice type prepreg and the prepreg at a predetermined temperature and pressure to produce a lattice panel (S600).

At this time, the mold manufacturing step is characterized in that the upper edge portion of the laminated groove of the mold is produced to have a predetermined curvature.

In addition, the preparation step is characterized in that the material of the raw material is a fiber-reinforced composite material of the fabric type.

In addition, the cutting step is characterized in that the cutting based on the fiber direction of the grid-shaped prepreg in order to minimize the loss of the material.

At this time, the cutting step is characterized in that the grid-shaped prepreg is produced in an orthogonal shape based on the fiber direction.

On the other hand, the first lamination step is characterized in that it further comprises a pressing step (S410) for pressing the lattice prepreg in a vacuum state for each preset number of stacked.

In this case, the first lamination step and the second lamination step are characterized in that the prepreg and lattice-shaped prepreg is dropped and stacked along the length direction based on the design concept and load conditions of the object to which the lattice panel is applied.

As described above, the present invention can freely set the spacing and thickness between gratings for the grating structure, and can be variously applied according to the intention of the structure or the designer to which the grating panel is applied, and for the direction of the grating (outward or inward). It is possible to have free design and high design freedom.

In addition, the present invention is capable of manufacturing a grid panel consisting of a three-dimensional curved shape instead of a conventional flat grid panel panel has an effect that can actively correspond to the shape of the application target.

1 is a flow chart showing a manufacturing method of a laminated lattice panel according to a preferred embodiment of the present invention;
2 is a view showing a mold of a laminated lattice panel according to a preferred embodiment of the present invention;
3 is a view illustrating a concept in which a prepreg and a lattice prepreg are stacked in a mold according to a preferred embodiment of the present invention;
Figure 4 is a schematic cross-sectional view showing one side of the laminated grid panel according to an embodiment of the present invention,
5 is a view schematically showing a laminated grid panel according to another embodiment of the present invention.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description.

However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, similar reference numerals are used for similar elements.

When a component is said to be "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in the middle. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. Hereinafter, the same reference numerals are used for the same components in the drawings, and duplicate descriptions of the same components are omitted.

Hereinafter, with reference to the accompanying drawings, it will be described embodiments of the present invention. Like reference numerals in the drawings denote like elements. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

First, Figure 1 is a flow chart showing a manufacturing method of a laminated lattice panel according to a preferred embodiment of the present invention, Figure 2 shows a mold of a laminated lattice panel according to a preferred embodiment of the present invention, Figure 3 is a preferred embodiment of the present invention FIG. 4 is a view illustrating a concept in which a prepreg and a lattice type prepreg are stacked in a mold, and FIG. 4 is a view schematically showing a cross-section of one side of a laminated lattice panel according to a preferred embodiment of the present invention, and FIG. 2 is a view schematically illustrating a stacked lattice panel according to another embodiment.

Accordingly, the manufacturing method of the laminated lattice panel according to the present invention is largely mold manufacturing step (S100), preparation step (S200), cutting step (S300), the first lamination step (S400) as shown in FIG. ), The second lamination step (S500) and the molding step (S600).

First, the mold manufacturing step is a step of manufacturing a mold 100 having a lattice pattern lamination groove 110 is provided on the surface, a plurality of blocks 120 partitioned by the lamination groove is formed.

At this time, the mold manufacturing step is characterized in that the upper edge portion of the laminated groove of the mold is produced to have a predetermined curvature.

That is, the laminated groove of the mold is formed so that the upper edge portion has a curvature, and serves to prevent the delamination of the prepreg and the stress concentration between the panels when forming the grid panel later.

In this case, the set curvature may be formed to have a one-way curvature of 3,500mm based on the lower surface of the mold, as shown in FIG.

Next, a preparation step of preparing the prepreg 200 by pre-impregnating the raw material for laminating to the mold in the resin.

In this case, the raw material is characterized in that the material is a fabric-reinforced fiber-reinforced composite material, it may be preferably formed of plain weave fabric (CFRP, Carbon Fiber Reinforced Plastics).

Here, the mechanical properties of the plain woven carbon fiber reinforced composite material is shown in Table 1.

Property Symbol Value Unit   Lomg. Modulus E ₁₁ 64.02 GPa   Trans. Modulus E ₂₂ 64.02 GPa   In-plane shear modulus G ₁₂ 3.65 GPa   Poisson ’s ratio ν ₁₂ 0.06   Density ρ 1550 ㎏ / ㎥   Ply thickness t 0.2 mm

Prepreg can be prepared by preimpregnating such a plain woven carbon fiber reinforced composite material into a resin.

Next, a cutting step (S300) of manufacturing the lattice type prepreg 300 by cutting the prepreg in a lattice pattern to correspond to the shape of the stack groove of the mold.

At this time, the cutting step is characterized in that the cutting based on the fiber direction of the grid-shaped prepreg in order to minimize the loss of the material.

That is, in order to minimize the loss of the material by cutting in consideration of the direction of the fabric fibers of the above-mentioned plain weave carbon fiber reinforced composite material, the grid-shaped prepreg in an orthogonal grid based on the fiber direction It is characterized by being manufactured.

Next, a first lamination step (S400) of laminating the lattice type prepreg in the lamination groove of the mold.

In this case, the first lamination step may further include a pressing step (S410) for pressing the lattice prepreg in a vacuum state for each preset number of stacked.

That is, the lattice prepregs are sequentially stacked in the lamination grooves of the mold, so that the lattice prepregs are stacked in a vacuum state by using compression pads for each set number of laminations in order to prevent interlayer separation between materials. It is formed to be pressed in.

In this case, preferably, the preset stacking number may be set to 3 to 4 sheets.

Next, a second lamination step S500 of stacking the prepreg on top of the lattice prepreg.

That is, when lamination of the lattice type prepreg in the lamination groove of the mold is completed, the prepreg is sequentially stacked on the lamination prepreg.

At this time, as shown in Figure 5, the first and second lamination step is the prepreg and lattice-shaped prepreg drop along the longitudinal direction based on the design concept and load conditions of the object to which the lattice panel is applied It is characterized by laminating.

In other words, when the laminated lattice panel of the present invention is applied to an actual structure, it is divided into a part that receives a lot of load and a part that receives a lot of loads. .

Therefore, as described above, by stacking the prepreg and the lattice-shaped prepreg along the longitudinal direction, the portion under high load to support the load by making the grating thick and high, the portion under the low load By making it narrow and low, the shape of the grid can be optimized according to the size of the load.

That is, as shown in Figure 5, the detailed description of each lattice region of the laminated grid panel according to another embodiment of the present invention is as follows.

① The first lattice area 410-A lattice for relatively loaded parts, designed to be thicker and thicker than the second lattice area.

② First transition region 420-This is a transition region for smoothly connecting the second grid region in the first grid region, and is laminated by dropping the fiber constantly along the longitudinal direction.

③ The second lattice region 430-A grid for relatively low loads, designed to be lower and narrower than the first lattice region.

④ second transition region 440-a region extending from the second grid region to the panel region, in which the fibers are dropped and laminated in the same manner as the first transition region;

⑤ Panel Area 450-Area consisting of only panels without grids

Such a laminated grid panel according to another embodiment of the present invention has the advantage that can be optimized for the applied structure.

Finally, forming the lattice panel by molding the laminated lattice type prepreg and the prepreg at a predetermined temperature and pressure (S600).

At this time, the molding step may be preferably molded integrally through the autoclave process, the predetermined temperature and pressure are shown in Table 2.

The curing cycle

In order to confirm the mechanical properties of the laminated lattice panel manufactured according to the above-described manufacturing method, the tensile lattice panel and the lattice-less panel were subjected to tensile and compression, shear, and bending load tests in the axial direction using an MTS material tester.

At this time, the laminated lattice panel has a size of 360 x 360 mm 2, the cell size between the gratings is a square shape of 93 x 93 mm 2, the width and thickness of the grating is 4 mm, the weight is 780g.

In addition, the lattice-free panel was 360 × 360 mm 2, and the specimen weight was 645 g.

② axial tensile and compression test

Tensile load was added to the laminated lattice panel and the panel without lattice, respectively, and the compressive load was 10 kN in the X direction and 15 kN in the Y direction for the safety of the test. The setup of the axial tension and compression test is shown in Table 3.

Set up of axial tensile-compressive test
(a) non-grid structure / (b) grid structure

The results of the load test in the X direction are shown in Table 4.

Load-deflection results corresponding to x-direction
(a) under tensile load / (b) under compressive load

As shown in the table above, the test results confirm that the proposed specimen is in the linear deformation section under the test conditions in the X direction. The mechanical behavior predicted by the finite element analysis and the results obtained in the actual test were judged to be similar, and the validity of the present finite element model method and analysis was demonstrated.

Although the deformation of the lattice panel specimens appears smaller in the tensile compression behavior in the X direction, it is judged that the effect of the increase of in-plane rigidity due to the lattice is not significantly highlighted.

On the other hand, as a result of linear buckling analysis under X-direction compressive load, the buckling critical load was calculated to be 15.8 kN for the latticeless panel and 26.6 kN for the laminated lattice panel. That is, although the weight increase of 21% arises by a grating | lattice, it is thought that the buckling load increase effect of about 68% is due to the increase of rigidity of an out-of-plane direction.

Accordingly, the results of the buckling mode analysis under the X-direction compressive load are shown in Table 5.

Buckling mode under x-directional compressive load
(a) non-grid structure / (b) grid structure

On the other hand, the test results for the load in the Y direction is shown in Table 6.

Load-deflection results corresponding to y-direction
(a) under tensile load / (b) under compressive load

That is, in the Y-direction, there is a one-way curvature, so that a higher deformation appears than the test in the X-direction at the same load. In the Y direction, the analytical value was predicted to be larger than the measured value. This is judged to be an error due to curvature, but tendency can be seen that the similarity between analysis and test appears.

Thus, as in the X-axis test, the deformation of the laminated lattice panel is smaller but the effect of increasing the in-plane stiffness by the lattice is not significant. As mentioned, the Y-direction compression was expected to be susceptible to buckling due to the unidirectional curvature. As a result of the test, a large strain began to occur at about -7 kN for the lattice-free panel.

On the other hand, in the case of a laminated lattice panel it can be seen that the linearity is maintained to -15 kN. In the finite element model, the buckling critical load was calculated to be -10 kN for panels without lattice, while -17 kN for stacked lattice panels.

In other words, the proposed laminated grating panel increases the weight by 21% compared with the panel without the grating, but improves the stiffness in the out-of-plane direction and increases the buckling critical load by 70% in the curved direction, which is considered to be effective in preventing buckling. do.

In addition, the results of the buckling mode analysis for the Y-direction compressive load are shown in Table 7, and the buckling phenomenon occurred in the Y-axis compression test is shown in Table 8.

That is, as shown in Tables 7 to 8 below, it can be seen that the lattice structure is maintained under the buckling load of the non-lattice structure, and the buckling mode shown in the test is similar to the analysis.

Buckling mode under y-directional compressive load
(a) non-grid structure / (b) grid structure

Deformed shape of specimen under compression load
(a) non-grid structure / (b) grid structure

③ shear test

Shear test is made of jig as shown in Table 9, and the test was composed, and each corner was equipped with a ball bearing to enable shear deformation. In the shear test, the behavior of the structure was confirmed by applying a load of 10 kN.

Set up of shear test
(a) non-grid structure / (b) grid structure

The test results and analysis results for the shear load test described above are shown in Table 10.

Load-deflection results under shear load

From the shear load test results, it can be seen that the deformation of the non-lattice structure is smaller than the lattice structure in the linear section under a certain load, but this is judged as an error level that may occur in the shear jig set-up including complex components. There seems to be no big difference. On the other hand, in the case of a panel without a grid, it was confirmed that some nonlinear sections appeared as the load increased. This is considered to be due to the curvature of the Y direction, which is a geometric characteristic of the specimen.

However, in the case of the laminated lattice panel proposed by the present invention, such a phenomenon does not appear, and thus, it is determined that the lattice structure mitigates the nonlinear phenomenon due to curvature.

④ 3-point bending test

The bending load test was carried out by controlling the displacement by installing as shown in Table 11. Both ends of the specimen span the test fixture, and the structural behavior of each specimen was examined by applying a load at the center position. Reflecting the test conditions, the finite element model was also analyzed by simple supporting conditions and the results were calculated.

Set up of 3-point bending test
(a) non-grid structure / (b) grid structure

The results for the above bending load test are shown in Table 12 below.

Load-deflection results under bending load

This bending load test was carried out under the same displacement (10 mm) conditions, and the load of the laminated lattice panel was measured about 2.7 times compared to the panel without lattice.

In addition, in the case of the laminated lattice panel, it seems to agree with the value predicted by the analysis, and in the case of the panel without the lattice, there is some difference in load, but the tendency is consistent.

This proved through tests and analysis that the grating structure improved the panel's bending stiffness approximately 2.7 times.

As described above, the present invention can freely set the spacing and thickness between gratings for the grating structure, and can be variously applied according to the intention of the structure or the designer to which the grating panel is applied, and the outward or inward direction of the grating. It is possible to freely arrange and have a high design freedom.

In addition, the present invention is capable of manufacturing a grid panel consisting of a three-dimensional curved shape instead of a conventional flat grid panel panel has an effect that can actively correspond to the shape of the application target.

The best embodiments have been disclosed in the drawings and the specification. Herein, specific terms have been used, but they are used only for the purpose of illustrating the present invention and are not intended to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

100 ... mold 110 ... laminated groove
120 ... block 200 ... prepress
300 ... lattice prepregs
S100 ... mold production step S200 ... preparation step
S300 ... Foundation stage S400 ... Deposition stage
S500 ... second lamination step S600 ... molding step

Claims (8)

In the manufacturing method of the grating panel,
A mold manufacturing step (S100) having a lattice pattern lamination groove 110 provided on a surface thereof, and manufacturing a mold 100 in which a plurality of blocks 120 partitioned by the lamination grooves are formed;
A preliminary step (S200) of preparing a prepreg 200 by pre-impregnating a raw material for laminating in the mold in a resin;
A cutting step (S300) of cutting the prepreg into a lattice pattern so as to correspond to a shape of a stack groove of the mold to produce a lattice type prepreg 300;
A first stacking step (S400) of stacking the lattice type prepreg into the stack groove of the mold;
Stacking the prepreg on top of the lattice prepreg (S500); And
It comprises a molding step (S600) of forming the lattice panel by molding the laminated lattice type prepreg and prepreg at a predetermined temperature and pressure,
In the mold manufacturing step, the upper edge portion of the laminated groove of the mold is manufactured to have a predetermined curvature,
The raw material of the preparation step, characterized in that the fabric-type fiber-reinforced composite material, a method of manufacturing a laminated grid panel.
delete delete The method of claim 1, wherein the cutting step
Method of manufacturing a laminated grating panel, characterized in that the cutting based on the fiber direction of the grating prepreg in order to minimize the loss of material.
The method of claim 4, wherein the cutting step
The lattice type prepreg is a manufacturing method of a laminated lattice panel, characterized in that the fabricated in an orthogonal shape based on the fiber direction.
The method of claim 1, wherein the first stacking step
The method of manufacturing a laminated grid panel further comprises a pressing step (S410) for pressing the grid-shaped prepreg in a vacuum state for each preset number of stacked.
The method of claim 1, wherein the first stacking step and the second stacking step
A method of manufacturing a laminated lattice panel according to the design concept of the object to which the lattice panel is applied and the load condition, the prepreg and the lattice type prepreg are dropped along the longitudinal direction.
A laminated lattice panel, which is produced by the method of any one of claims 1 and 4.

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