JPS5953866B2 - sandwich panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sandwich panel composed of a face material and a core material, and particularly to a sandwich panel having a cross-sectional shape suitable for reducing the weight of the face material.

Sandwich panels have traditionally been used in fields such as aircraft, vehicles, ships, and architecture because of their characteristics of being strong despite being lightweight and thin.
These sandwich panels will be described below with reference to the drawings. 1 to 4 show typical conventional sandwich panels. In the figure,
1 and 1' are flat plate face materials, and 2 to 6 are core materials, which are honeycomb, corrugated sheet, pulsar material, foamed material, and spherical material, respectively. In general, properties such as strength, soundproofing, and heat insulation of a sandwich panel vary depending on the material and structure of the core material. Those using the metallic honeycomb 2 and corrugated plate 3 as shown in FIGS. 1 and 2 as the core material have almost no problems in terms of strength, but the upper and lower facing materials 1 and 1 ' becomes a contact state between metals, which is disadvantageous for heat insulation. They are also generally expensive. The i-way, as shown in Figures 3 and 4, uses pulsar material 4 and foam material 5 as core materials,
Conversely, it has excellent soundproofing and heat insulation properties, but its strength properties deteriorate.

In particular, when foam material 5 is used, the core material is inelastic and has almost no hardness, so when a localized concentrated load is applied to the facing material, the facing material will undergo local deformation as the plate thickness decreases. more likely to occur. For this reason, when using design specifications that severely limit local deformation, or the amount of denting, such as vehicle flooring, the thickness of the face material is increased compared to sanderch panels with other core materials. This is disadvantageous in terms of weight reduction. Moreover, in the case of balsa wood 4, the weight of the core material is large, which has the drawback of increasing the overall weight. Figures 5a and 5b show a structure that has recently been studied that incorporates the individual features of the sanderch panels shown in Figures 1 to 4, and is made of lightweight, inexpensive polymeric material with elastic core material. A hollow ball 6 is used. When this ball material 6 is subjected to a load P as shown in FIG. 6, it undergoes elastic deformation as shown in the figure, so the surface material 1 as a whole exhibits a deformation behavior similar to that of an elastic flooring beam shown in FIG. . However, in this case as well, when the load point is located at the midpoint of the adjacent balls 6, as shown in section D of FIG. tends to cause local deformation. For this reason, it is difficult to make the face material thinner, that is, to further reduce the weight of the sandwich panel.The purpose of the present invention is to improve local rigidity by effectively demonstrating the material strength characteristics of the face material. The object of the present invention is to provide a sanderch panel that is lightweight and has sufficient strength by reducing the thickness of the facing material.

A feature of the present invention is that in a sanderch panel that uses a hollow spherical material as the core material, the cross-sectional shape of the face material that receives an out-of-plane load that acts on the face material is partially attached to the spherical core material. In addition, by creating a corrugated shape, the in-plane force can be approximated, improving the local rigidity of the face material and making it possible to reduce the thickness of the face material.

Next, a sandwich panel which is an embodiment of the present invention will be described in detail using the drawings.

Figures 8a and 8b show a sandwich panel to which the present invention is applied. In the figure, the ball 6 and the adhesive 7 are the same as before, and the face materials 9 and 9'' have an uneven cross section that matches the four-curved shape of the ball 6 (hereinafter referred to as
(referred to as wavy surface material). The sanderch panel is basically composed of such parts, and the corrugated panels 9 and 9'' and the hollow spheres 6 are each bonded with an adhesive 7.The spheres 6
is made of a polymeric material that is elastic and has excellent sound and heat insulation properties. When a load from outside the plane is applied to such a sanderch panel, the individual balls 6 exhibit elastic deformation behavior as shown in FIG. 7, and the load is shared by the entire panel.

On the other hand, the so-called local deformation between the spheres 6 of the corrugated surface material 9, which greatly affects the amount of indentation due to permanent deformation, is caused by the area surrounded by the spheres 6 being a hemispherical surface as shown in Fig. 9, and the distributed load is When modeled as acting, it becomes membrane displacement as shown by equation (1) within the elastic range.

For comparison, the case of conventional flat plate (hereinafter referred to as flat plate)
Similarly, when modeled as shown in FIG. 10, the maximum deformation amount becomes equation (2). Therefore, assuming K1=R for the He type and 'T' concave material T and hj, and comparing equations (1) and (2) by expressing the load P/δ per unit deformation, we get (3)
It becomes like the expression.

Here, K,: (P/δ) of the corrugated surface material/(P of the flat surface material)
/δ) In formula (3), R2 for the Sanderch panel
〉2t2, and K,〉1.

In other words, in the case of a corrugated panel, the amount of deformation for the same load is smaller than that of a flat panel. Further, the maximum stress is expressed by equations (4) and (5), respectively. Here ゛, σ
W, σp: Stress (Kg/Mm2) When compared in the same manner as in the case of the amount of deformation described above, equation (6) is obtained.

Here, KO: stress of corrugated surface material/stress of flat surface material (6)
In the formula, 2t<3R, and KO×1.

In other words, the stress is smaller in the case of a rectangular plate than in the case of a flat plate. As is clear from FIG. 11, the relationship between the amount of deformation and the stress between the two is such that a convex portion is formed on the corrugated surface material 9 at the bonding surface between the surface material 9 and the ball material 6, and the surface material is the same as the ball material 6. By giving a radius of curvature of
, R1/R times. The relationship between the amount of deformation and the stress between the corrugated and flat face members tends to be almost the same even when a concentrated load is applied. As is clear from the above results, by providing the face material with a wave-like shape with a radius of curvature close to a spherical shape, the load from outside the plane acting on the face material becomes an in-plane force, and the amount of denting and stress due to permanent deformation are reduced. becomes smaller.

Therefore, it is possible to reduce the thickness of the face material having a large weight ratio in the entire sanderch panel, thereby making it possible to reduce the weight. In addition, the soundproofing and heat insulating properties are almost the same as in the case of using a conventional foam material and core material, since the hollow sphere material 6 is used and an air layer is provided between the upper and lower face materials. Figures 12a and 12b show other application examples of the present invention;
What differs from Figure b is that the ball 6'' is in contact with the recesses 9a and 9''a of the corrugated panel 9, and therefore the outer surface of the ball 6'' has a contact portion 6a with the panel 9. It is concave.

Further, FIG. 13 shows still another modification of the present invention, in which even when a hemispherical core material 10 is used, the concave portion of the corrugated surface material 9 is the aspherical portion 10 of the hemispherical surface 10. , a, and are assembled so that the convex portion is in contact with the spherical portion 10b. Such a combination of face material and core material also has the same effect as described above. According to the present invention, in order to increase the rigidity of the non-contact part of the face material with the ball material, the thickness of the face material, which accounts for most of the overall weight of the sanderch panel, can be made thinner, resulting in weight reduction. effective.

[Brief explanation of the drawing]

Figures 1 to 4 show typical conventional sanderch panels. Figure 1 has a honeycomb core, Figure 2 has a corrugated core, and Figure 3 has a balsa core. , Fig. 4 is a schematic structural diagram of the case where foam material is used as the core material, Fig. 5a is a structural diagram of the currently considered sanderch panel using spherical material as the core material, and Fig. 5b is the Figure 5a is a sectional view taken along line A-A, Figure 6 is an explanatory diagram showing the state of elastic deformation of the ball shown in Figure 5, and Figure 7 is an illustration of the sanderch panel shown in Figure 5 when an out-of-plane load is applied. Fig. 8a is an explanatory diagram showing the deformed state of the facing plate in the case of the present invention, and Fig. 8a is a structural diagram showing a sanderch panel in which the facing plate has a corrugated cross-sectional shape.
Figure b is a B-B sectional view of Figure 8a, Figures 9 and 10 are explanatory diagrams locally modeling the case where an out-of-plane load is applied to the inventive and conventional surface materials, FIG. 11 is an explanatory diagram showing details of the bonding state of the corrugated panel and the spherical core material in the present invention, and FIGS. 12a and 13 each show a sandwich panel which is an application example of the present invention. Fig. 12a shows the state in which the contact position between the corrugated surface material and the ball material is changed, Fig. 13 is a structural diagram showing the case where the core material is a hemispherical material, and Fig. 12b is the C-C cross section of Fig. 12a. It is a figure. 1,1″...Face material, 6...Hollow ball material, 9,9″・
...Corrugated surface material, 10...Semispherical material.

Claims (1)

[Scope of Claims] 1. In a sandwich panel consisting of opposing face plates made of metal or composite materials and a plurality of spherical core members sandwiched between the face plates, the cross-sectional shape of the face plates is wave-shaped. A sandwich panel characterized by: 2. In the sandwich panel according to claim 1, the wavy convex portion of the face material is in contact with the spherical core material, and the concave portion of the face material is located at the midpoint between the adjacent core material. A sandwich panel characterized by combining the above-mentioned face material and core material. 3. In the sandwich panel according to claim 1, a concave portion of an arbitrary size is provided on the outer surface of the spherical core material, and the concave portion of the face material is aligned and in contact with the concave portion of the core material, and the face material A sandwich panel characterized in that a face material and a core material are combined so that the convex portion of the panel is located at a midpoint between two adjacent core materials. 4. In the sandwich panel according to claim 3, the core material is made into a hemispherical shape by forming a large recessed portion, and the recessed portion of the face material is located on the aspherical surface portion of the hemispherical core material, and A sandwich panel characterized in that a face material and a core material are combined so that a convex part of the material contacts a spherical part of a hemispherical core material. 5. A sandwich panel according to claim 1, 2, 3, or 4, characterized in that the core material is hollow and made of a polymeric material.