Sandwich panel structure and sandwich panel structure manufacturing method

Abstract

This sandwich panel structure (1) comprises a plurality of split members (11). The split members (11) each comprise two sheets of a skin material (12) and a core material (13) disposed between the two sheets of the skin material (12). In a joining part (31) of the plurality of split members (11), a groove part (23), formed by thinning the skin material (12) in a range in which the outer surface of the core material (13) is not exposed, is present in the skin material (12). A patch member (21) is disposed in the groove part (23) via an adhesive (22). In a state in which the plurality of split members (11) are joined, the total thickness of the skin material (12), the adhesive (22), and the patch member (21) in the joining part (31) in the plate thickness direction, and the thickness of the skin material (12) in a non-joining part (32) in the plate thickness direction are continuous at the boundary between the joining part (31) and the non-joining part (32).

Description

Sandwich panel structure and method for manufacturing sandwich panel structure

[0001] The present disclosure relates to sandwich panel structures and methods for manufacturing sandwich panel structures.

[0002] Demand for higher functionality in communication and broadcasting satellites is increasing, necessitating the installation of high-performance, power-hungry communication devices. To achieve this, larger solar panels are required. Here, a solar panel is a structure consisting of a sandwich panel substrate and multiple solar cells mounted thereon. Increasing the size of a sandwich panel structure is crucial to increasing the size of solar panels. In sandwich panel structures, the core and skin materials must be integrated. Therefore, conventional technologies have a problem in that the upper limit of size is limited by the size of the forming furnace. To address this issue, a method has been developed to realize a large sandwich panel structure by joining multiple divided sandwich panel structures in a post-process. By dividing the sandwich panel structure into multiple pieces within the size constraints of the forming furnace, it is possible to increase the size of the sandwich panel structure without being bound by the size constraints of the forming furnace. Patent Document 1 discloses a sandwich structure and a method for manufacturing the same. The sandwich structure disclosed in Patent Document 1 has a core material and FRP (Fiber Reinforced Plastics) skin plates arranged on both sides of the core material, with the ends butted together, and is characterized by having an FRP connecting layer extending over the surfaces of both ends and a layer containing a resin diffusion medium between the butted end faces.

[0003] Japanese Patent Application Laid-Open No. 2000-108232

[0004] The technology disclosed in Patent Document 1 enables the strong joining of multiple divided sandwich structures by providing an FRP tie layer extending over the surfaces of both ends at butt-jointed joints in the sandwich structure. However, in the sandwich structure disclosed in Patent Document 1, because the FRP tie layer is provided on the surface of the FRP skin plate, the thickness of the FRP layer consisting of the FRP skin plate and the FRP tie layer at the joint is thicker than at non-jointed areas. The technology disclosed in Patent Document 1 has problems, such as uneven thermal deformation due to this uneven thickness and reduced strength at the joint between the joint and non-jointed areas. A specific example of such a joint is the boundary between the area where the FRP tie layer 6 is present and the area where it is not present in Figures 5 to 7 of Patent Document 1. The present disclosure aims to provide a sandwich panel structure in which the thickness of the joint and non-jointed areas in the thickness direction is continuous at the boundary between the joint and non-jointed areas in the thickness direction.

[0005] A sandwich panel structure according to the present disclosure is a sandwich panel structure comprising a plurality of divided members, each of which is a first divided member and which is to be joined to a second divided member of the plurality of divided members, wherein the first divided member is comprised of two skin materials and a core material disposed between the two skin materials, one of which is a first target skin material, wherein at a joint of the first divided member to the second divided member, the first target skin material has a groove formed by thinning the thickness of the first target skin material to an extent that the outer surface of the core material is not exposed, and wherein when the first divided member and the second divided member are joined together, a patch member is disposed in the groove via an adhesive, At the boundary between the joint portion and the non-joint portion, which is the portion of the first divided member other than the joint portion, the total thickness in the plate thickness direction of the first target skin material, the adhesive, and the patch member at the joint portion is continuous with the thickness in the plate thickness direction of the first target skin material at the non-joint portion.

[0006] According to the present disclosure, when the first divided member and the second divided member are joined, the total thickness in the thickness direction of the first target skin material, the adhesive, and the patch member at the joint is continuous with the thickness in the thickness direction of the first target skin material at the non-jointed portion at the boundary between the joint and non-jointed portion. Therefore, according to the present disclosure, it is possible to provide a sandwich panel structure divided into multiple parts, in which the thickness in the thickness direction of the joint and the thickness in the thickness direction of the non-jointed portion are continuous at the boundary between the joint and non-jointed portions.

[0007] 1 is a perspective view showing an example of the configuration of a sandwich panel structure 1 according to embodiment 1. FIG. 2 is a cross-sectional view showing an example of the configuration of a sandwich panel structure 1 according to embodiment 1. FIG. 3 is an enlarged cross-sectional view showing an example of the configuration of a sandwich panel structure 1 according to embodiment 1. FIG. 4 is a side view showing an example of the configuration of a sandwich panel structure 1 according to embodiment 2. FIG. 5 is an enlarged cross-sectional view showing an example of the configuration of a sandwich panel structure 1 according to embodiment 3. FIG. 6 is an enlarged cross-sectional view showing an example of the configuration of a sandwich panel structure 1 according to embodiment 4. FIG. 7 is a top view showing an example of the configuration of a sandwich panel structure 1 according to embodiment 5. FIG. 8 is an explanatory diagram showing a specific example of a method for manufacturing a sandwich panel structure 1 according to embodiment 6, where (a) is a diagram illustrating a member molding process, (b) is a diagram illustrating a groove / patch member processing process, (c) is a diagram illustrating a placement process, and (d) is a diagram illustrating an integration process.

[0008] In the description of the embodiments and the drawings, the same elements and corresponding elements are denoted by the same reference numerals, and the description of the elements denoted by the same reference numerals will be omitted or simplified as appropriate.

[0009] First Embodiment Hereinafter, the present embodiment will be described in detail with reference to the drawings.

[0010] 1 is a perspective view showing an example of the configuration of a sandwich panel structure 1 according to embodiment 1. The sandwich panel structure 1 is made up of a plurality of segment members 11, patch members 21, and adhesive 22.

[0011] Each segment 11 is composed of two skin materials 12 and a core material 13 disposed between the two skin materials 12. Grooves for disposing patch members 21 are formed in the segment 11 by thinning the skin materials 12 to an extent that the outer surface of the core material 13 is not exposed. The thickness of the segment 11 is the length of the segment in the thickness direction. The thickness direction is the normal direction to the top surface of the sandwich panel structure 1. The top surface of the sandwich panel structure 1 is a surface consisting of the skin materials 12 and the patch members 21, and is the surface where the core material 13 is not exposed. The sandwich panel structure 1 is integrally formed by joining two adjacent segment members 11 together via adhesive 22 and the patch members 21.

[0012] The configuration of the joint 31 will be described in detail below using specific examples. FIG. 2 is a cross-sectional view showing an example of the configuration of the sandwich panel structure 1. The cross-section is a plane having the same normal as the normal to the side surface of the sandwich panel structure 1 that includes the joint 31, as shown in FIG. 2 . The direction perpendicular to both the normal to the cross-section and the thickness direction of the sandwich panel structure 1 is referred to as the longitudinal direction. Regarding the region of the sandwich panel structure 1 when viewed along the longitudinal direction, as shown in FIG. 2 , the region where the patch member 21 is present is referred to as the joint 31, and the region other than the joint 31 is referred to as the non-jointed region 32. The joint 31 is a portion that is joined to another segment 11. FIG. 2 shows a flat sandwich panel structure with a uniform thickness as an example of the sandwich panel structure 1. The sandwich panel structure 1 shown in FIG. 2 consists of two segment members 11 separated by a plane whose normal is the longitudinal direction.

[0013] The skin material 12 has grooves 23 at the joints 31 into which the patch members 21 are fitted. The grooves 23 are formed by thinning the skin material 12 at the joints 31 to a degree that does not expose the surface of the core material 13 when the sandwich panel structure 1 is viewed from the thickness direction. The skin material 12 is not cut at the boundary between the joints 31 and the non-jointed portions 32. That is, the skin material 12 is continuous along the longitudinal direction of the sandwich panel structure 1 at the boundary. The patch members 21 are members having a rectangular cross section. Each patch member 21 is joined to each of the two skin materials 12 by fitting it into the grooves 23 provided in each of the two skin materials 12 via adhesive 22. As a specific example, aluminum alloy (A5052) can be used for each of the skin materials 12 and the patch members 21.

[0014] At the joints 31, the core material 13 constituting each segment 11 is joined to the opposing core material 13 via adhesive 22. Specifically, an aluminum alloy honeycomb core can be used as the core material 13, and a film-like adhesive (REDUX (registered trademark) 312, manufactured by Hexcel) can be used as the adhesive 22. The thickness of the core material 13 does not change at the boundary between the joint 31 and the non-jointed portion 32. The core material 13 is located between the two skin materials 12 throughout the entire longitudinal direction. The core material 13 is joined to the skin materials 12 via adhesive 22. At the joints 31, the skin materials 12 constituting each segment 11 are joined to the core material 13 or the skin material 12 of the opposing segment 11 via adhesive 22 on the surfaces that do not contact the patch member 21.

[0015] FIG. 3 is a diagram showing an example of the configuration of a sandwich panel structure 1, and is an enlarged cross-sectional view of one side of the sandwich panel structure 1. In FIG. 3 , the thickness of the patch member 21 in the thickness direction is set to be equal to the difference between the depth of the groove 23 in the thickness direction and the thickness of the adhesive 22 in the thickness direction. As a specific example, when the thickness of the patch member 21 is 500 μm and the thickness of the adhesive 22 is 50 μm, the depth of the groove 23 is 550 μm. In this example, by setting the thickness of the patch member 21 to be equal to the difference between the depth of the groove 23 and the thickness of the adhesive 22, the height of the surface of the skin material 12 in the non-bonded portion 32 in the thickness direction becomes the same as the height of the surface of the patch member 21 in the bonded portion 31 in the thickness direction. This ensures the smoothness of the surface of the sandwich panel structure 1. Furthermore, since the skin material 12 in the non-bonded portion 32 is similar to the combined configuration of the skin material 12 and patch member 21 in the bonded portion 31, a relatively high degree of homogeneity can be obtained between the non-bonded portion 32 and the bonded portion 31.

[0016] That is, in this embodiment, when each of the plurality of dividers 11 is defined as a first divider and the first divider is joined to a second divider of the plurality of dividers 11, the following holds true. Specifically, the sandwich panel structure 1 comprises a first divider, a second divider, a patch member 21, and an adhesive 22. Each of the first divider and the second divider comprises two skin members 12 and a core member 13 disposed between the two skin members 12. Here, one of the two skin members 12 of the first divider is defined as a first target skin member. At the joint 31 where the first divider is joined to the second divider, the first target skin member has a groove 23 formed by thinning the thickness of the first target skin member to an extent that the outer surface of the core member 13 is not exposed. When the first divider and the second divider are joined, a patch member 21 is disposed in the groove 23 via the adhesive 22. In this state, at the boundary between the bonded portion 31 and the non-bonded portion 32, the total thickness in the thickness direction of the first target skin material, adhesive 22, and patch member 21 in the bonded portion 31 is continuous with the thickness in the thickness direction of the first target skin material in the non-bonded portion 32. The non-bonded portion 32 is a portion of the first divided member other than the bonded portion 31. As a specific example, the depth in the thickness direction of the groove portion 23 is the same as the sum of the thickness in the thickness direction of the patch member 21 and the thickness in the thickness direction of the adhesive 22. The adhesive 22 is disposed between the first divided member and the patch member 21. Furthermore, the material of the first target skin material and the material of the patch member 21 may be the same.

[0017] Although the sandwich panel structure 1 has been described as having a uniform thickness and a flat plate-like shape, the sandwich panel structure 1 does not have to have a uniform thickness or a flat plate-like shape. The sandwich panel structure 1 may have a curved or cylindrical shape, and the thickness may vary from location to location. Although the sandwich panel structure 1 has been described as being composed of two segment members 11, the sandwich panel structure 1 may also be composed of three or more segment members 11. Although the dividing surface of the segment member 11 has been described as a surface normal to the longitudinal direction, the dividing surface may also be a surface normal to any other direction. For example, the dividing surface may be a surface normal to the paper plane or any direction within the plane between the longitudinal direction and the paper plane. Although an aluminum alloy has been described as being used as the material for the skin material 12 and the patch member 21, the material does not have to be an aluminum alloy. Specific examples of the material of at least one of the skin material 12 and the patch member 21 include metals such as stainless steel alloys or magnesium alloys, fiber-reinforced plastics (FRP) such as carbon fiber reinforced plastics (CFRP) or glass fiber reinforced plastics (GFRP), ceramics such as carbon fiber reinforced carbon (C / C) or silicon carbide (SiC), wood, plastics, etc. Although the above description has been given of the case where both the skin material 12 and the patch member 21 are made of aluminum alloys, i.e., where both are made of the same material, the skin material 12 and the patch member 21 may be made of different materials. Although the patch member 21 is provided on both skin materials 12 in the above description, the patch member 21 may be provided on only one of the skin materials 12. Furthermore, although the core material 13 is made of a honeycomb core in the above description, the material does not have to be a honeycomb core. The material may be a foam core, a flexible core, a paper core, or the like.Although the above description has been given of a case in which the thickness of the skin portion does not change between the joint portion 31 and the non-joint portion 32, the thickness of the skin portion may change continuously between the joint portion 31 and the non-joint portion 32. In other words, when the first and second divided members are joined, the thickness of the skin portion in the plate thickness direction may change continuously along the longitudinal direction of the sandwich panel structure 1 from the joint portion 31 to the non-joint portion 32. The skin portion is the entirety of the first target skin material, the adhesive 22 disposed between the first target skin material and the patch member 21, and the patch member 21. Although the above description has been given of a case in which the thickness of the skin material 12 changes discontinuously between the joint portion 31 and the non-joint portion 32, the thickness of the skin material 12 may change continuously between the joint portion 31 and the non-joint portion 32. In a case where the thickness of the skin material 12 continuously changes between the joint portion 31 and the non-joint portion 32, as a specific example, a slope is formed near the boundary between the joint portion 31 and the non-joint portion 32 of the first target skin material, and the thickness of the first target skin material in the plate thickness direction near the boundary changes tapered along the longitudinal direction. Although a film-like adhesive is used as the adhesive 22 in the above description, the adhesive 22 does not have to be a film-like adhesive. The adhesive 22 may be a one-component liquid adhesive, a two-component liquid adhesive, a foam adhesive, or the like. Although a single type of adhesive 22 has been described, the type of adhesive 22 may be changed depending on the location where the adhesive 22 is used. As a specific example, a foam adhesive is preferably used when joining core materials 13 having voids, such as honeycomb cores. Although a case where the cross section of the patch member 21 is rectangular has been described, the cross section of the patch member 21 does not have to be rectangular. The patch member 21 may be tapered in whole or in part. The cross-sectional shape of the patch member 21 may be any shape that matches the shape of the groove portion 23, and may be triangular, trapezoidal, or the like, for example. Although the ratio of the thickness of the adhesive 22 to the thickness of the patch member 21 is 1 / 10 in the above description, this ratio does not have to be 1 / 10. Specific examples of this ratio may be 10, 52, 1, 1 / 2, 1 / 5, 1 / 20, 1 / 50, 1 / 100, or the like.The smaller the ratio, the better, and more preferably, the smaller the ratio is than 1.

[0018] ***Description of Effects of Embodiment 1*** According to this embodiment, a groove 23 is formed in a segment 11, and a patch member 21 is placed in the groove 23. The patch member 21 and the groove 23 are bonded together via adhesive 22. The groove 23 is formed by thinning the skin material 12 of the segment 11. Therefore, at the boundary between the joint 31 and the non-jointed portion 32, the total thickness of the patch member 21, the skin material 12, and the adhesive 22 at the joint 31 can be made the same as the thickness of the skin material 12 at the non-jointed portion 32. Therefore, this embodiment can achieve a member in which the joint 31 and the non-jointed portion 32 are homogeneous. Furthermore, this embodiment can achieve a uniform structure at the joint 31 of the sandwich panel structure 1. Therefore, this embodiment can suppress stress concentration, thermal deformation, and the like.

[0019] Second Embodiment The following mainly describes the differences from the above-described embodiment with reference to the drawings.

[0020] *** Description of Configuration *** Figure 4 is a side view showing an example configuration of a sandwich panel structure 1 according to embodiment 2. The sandwich panel structure 1 has a skin-to-skin fitting portion 33. The skin-to-skin fitting portion 33 is an uneven portion formed on two opposing skin materials 12 so that the two skin materials 12 fit together at a joint 31. The two opposing skin materials 12 are the two skin materials 12 to be joined.

[0021] The configuration of the joint 31 will be described in detail below with specific examples. Figure 5 is a diagram showing an example of the configuration of a sandwich panel structure 1 according to embodiment 2, and is an enlarged cross-sectional view of one side of the sandwich panel structure 1. Figure 5 will explain the case where fiber-reinforced plastic (FRP) is used as the skin material 12. Each skin material 12 is composed of six layers, FRP layers 14a to 14f. Each FRP layer 14 is made of carbon fiber T800S (manufactured by Toray Industries, Inc.) and epoxy resin.

[0022] In Figure 5, only FRP layers 14a to 14c of FRP layers 14a to 14f are shown as FRP layers 14 for the left-hand segment. The left-hand segment is the segment 11 located on the left side in the figure. FRP layers 14a and 14b of the left-hand segment do not reach the core dividing surface 34 in the longitudinal direction, i.e., they do not reach the end of the core material 13 of the left-hand segment. Therefore, in the left-hand segment, FRP layers 14a and 14b form a recess at the skin-to-skin fitting portion 33.

[0023] 5, the FRP layers 14a and 14b of the right-side separate member protrude from the core dividing surface 34 in the longitudinal direction and extend beyond the end of the core material 13 of the right-side separate member to positions facing the FRP layers 14a and 14b of the left-side separate member. Therefore, in the right-side separate member, the FRP layers 14a and 14b form a convex portion at the skin-to-skin fitting portion 33. The right-side separate member is the separate member 11 located on the right side in the figure.

[0024] Furthermore, the FRP layer 14c is relatively long in the left-hand divided member and relatively short in the right-hand divided member. Therefore, the FRP layer 14c forms a convex portion in the left-hand divided member, and the FRP layer 14c forms a concave portion in the right-hand divided member. The FRP layer 14c of the left-hand divided member faces the FRP layer 14c of the right-hand divided member. The right-hand divided member may be considered the first divided member, and the left-hand divided member may be considered the second divided member. The longitudinal lengths of the convex portion of the left-hand divided member and the convex portion of the right-hand divided member at the skin-to-skin fitting portion 33 are each 20 mm. The FRP layer 14c forms the bottom surface of the groove 23 into which the patch member 21 is fitted. FRP layers 14d to 14f form the side surfaces of the groove 23. In this example, the sandwich panel structure 1 has skin-to-skin fitting portions 33 where the FRP layers 14a to 14c fit together, thereby enabling the two divided members 11 to be joined relatively firmly.

[0025] That is, the following holds true in this embodiment: A recess is formed in the first target skin material at the joint 31. A protrusion is formed in the second target skin material at the portion of the second divided member where the second divided member is joined to the first divided member (joint 31). The second target skin material is the skin material 12 provided in the second divided member, and is the skin material 12 that faces the first target skin material when the first divided member and the second divided member are joined. When the first divided member and the second divided member are joined, the recess and the protrusion fit together. The recess is formed on the joint surface where the first divided member and the second divided member are joined. The depth direction of the recess is the longitudinal direction of the sandwich panel structure. The protrusion is formed on the joint surface. The height direction of the protrusion is the longitudinal direction. The first target skin material and the second target skin material are each made of fiber-reinforced plastic. Each of the recess and the protrusion is made of a layer of fiber-reinforced plastic.

[0026] In this embodiment, carbon fiber is used as the reinforcing fiber of the fiber-reinforced plastic and epoxy resin is used as the matrix resin. However, other reinforcing fibers and matrix resins may be used to achieve desired characteristics. Specific examples of reinforcing fibers include glass fiber, aluminum oxide fiber, boron fiber, silicon carbide fiber, aramid fiber, Kevlar® fiber, Dyneema® fiber, Zylon® fiber, and hemp fiber. The fibers may be short or long fibers, or may be woven or braided using these fibers. Specific examples of matrix resins include unsaturated polyester resin, vinyl ester resin, phenolic resin, cyanate ester resin, polyvinyl acetate, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamide-imide, polyimide, and polyetherimide. While the longitudinal length of each of the left and right convex portions is 20 mm in the above description, the length does not have to be 20 mm. Specific examples of the length may be 10 mm, 50 mm, 100 mm, or 200 mm. Although the length of the convex portion of the left-side divided member and the length of the convex portion of the right-side divided member have been described, the lengths of the left-side divided member and the right-side divided member may be different. Although the number of convex portions of the left-side divided member and the right-side divided member is one each, the number of convex portions of each may be two or more.

[0027] ***Explanation of Effect of Embodiment 2*** According to this embodiment, the skin materials 12 are joined in a fitted state at the joints 31 of the sandwich panel structure 1. Therefore, according to this embodiment, the segment members 11 can be joined more firmly.

[0028] Third Embodiment Hereinafter, differences from the above-described embodiments will be mainly described with reference to the drawings.

[0029] *** Description of Configuration *** Figure 6 is a diagram showing an example configuration of a sandwich panel structure 1 according to Embodiment 3, and is an enlarged cross-sectional view of one side of the sandwich panel structure 1. The skin material 12 and the patch member 21 are each made of FRP and consist of multiple layers. Between the left and right divided members, each opposing layer has the same fiber orientation. The fiber content (Vf) of the skin material 12 is lower than that of the patch member 21. In other words, the fiber content of the patch member 21 is higher than that of the first target skin material.

[0030] The configuration of the joint portion 31 will be described in detail below with reference to a specific example. In Fig. 6, the patch member 21 has three layers, FRP layers 14d to 14f, and each skin material 12 has six layers, FRP layers 14a to 14f. The thickness of the skin material 12 in the non-joined portion 32 is 600 µm. The thickness of the patch member 21 is 270 µm, and the thickness of the adhesive 22 is 30 µm. The FRP layers 14d to 14f of the patch member 21 and the FRP layers 14d to 14f of the skin material 12 face each other. Each facing layer has the same fibers, resin, and fiber orientation.

[0031] Meanwhile, the fiber content of each of the FRP layers 14d to 14f of the patch member 21 is 56%. The Vf of each of the FRP layers 14a to 14f of the skin material 12 is 50%. Therefore, when the FRP layers 14a to 14c of the skin material 12, the adhesive 22, and the FRP layers 14d to 14f of the patch member 21 are viewed as a single unit at the joint 31, the Vf is 50%. Therefore, the Vf of the joint 31 and the Vf of the skin material 12 at the non-joined portion 32 are the same. Therefore, the homogeneity between the joint 31 and the non-joined portion 32 is high. In other words, in this embodiment, when the first and second divided members are joined, the material constituting the skin portion is continuous along the longitudinal direction at the boundary between the joint 31 and the non-joined portion 32.

[0032] ***Explanation of the Effects of Embodiment 3*** According to this embodiment, the opposing layers have the same fiber orientation, and the fiber content is consistent between the joints 31 and the non-joints 32. Therefore, according to this embodiment, a relatively high degree of homogeneity can be obtained between the joints 31 and the non-joints 32 of the sandwich panel structure 1.

[0033] Fourth Embodiment Hereinafter, differences from the above-described embodiments will be mainly described with reference to the drawings.

[0034] *** Description of Configuration *** Figure 7 is a diagram showing an example configuration of a sandwich panel structure 1 according to embodiment 4, and is an enlarged cross-sectional view of one side of the sandwich panel structure 1. In embodiment 4, the protruding convex portion of the skin-to-skin fitting portion 33 of the skin material 12 is configured to not warp due to thermal deformation. The convex portion according to this embodiment does not warp in the plate thickness direction beyond the standard warp value due to normal thermal deformation.

[0035] The structure of the joint 31 will be described in detail below with specific examples. In Figure 7, each skin material 12 is made up of seven layers, FRP layers 14a to 14g, made of the same material, and FRP layers 14a to 14d of the skin material 12 of the left-hand section face FRP layers 14a to 14d of the skin material 12 of the right-hand section. FRP layers 14e to 14g of the skin material 12 form the side surfaces of groove 23.

[0036] The FRP layers 14a to 14c are longer in the right-hand section than in the left-hand section. Therefore, a convex portion of the skin-to-skin fitting portion 33 is formed in the right-hand section. Furthermore, the FRP layers 14a to 14c are symmetrically laminated. More specifically, when the longitudinal direction is set to the 0° direction, the FRP layers 14a to 14c have a [0 / 90 / 0] orientation. Meanwhile, the FRP layer 14d is longer in the left-hand section than in the right-hand section. Therefore, a convex portion of the skin-to-skin fitting portion 33 is formed in the left-hand section. Furthermore, the FRP layer 14d is a single layer with a [0] orientation. Here, a single layer can be considered a symmetrical laminate. In other words, the convex layer is a symmetrical laminate. Symmetrical lamination of the same material does not cause deformation (warping) in the thickness direction. Therefore, when the segment member 11 is separated, no warping occurs in the right-side FRP layers 14a to 14c and the left-side FRP layer 14d, which correspond to the convex portion of the skin-to-skin fitting portion 33. This makes assembly of the segment member 11 relatively easy. Note that the expression "no warping" can also mean that the amount of warping is below a certain value. Furthermore, the patch member 21 is symmetrically laminated in a [0 / 90 / 0] ratio to match the orientation of the FRP layers 14e to 14g. Therefore, no warping occurs in the patch member 21.

[0037] The configuration of the FRP layer 14 corresponding to the convex portion of the skin-to-skin fitting portion 33 and the configuration of the patch member 21 have been described using the same material for each layer and symmetric lamination. However, the materials of each layer do not have to be the same, and symmetric lamination is not required; that is, the convex layer may be asymmetrically laminated. When using different materials for each layer, warping can be prevented by symmetrically laminating both the material and orientation. Furthermore, by using different materials for each layer, laminating them so that the orientation is asymmetric, and designing them to reduce the bending component of the thermal expansion coefficient, a warping-free configuration can be achieved. As a specific example, the warping in the thickness direction of the convex portion caused by thermal changes during molding can be configured to be 1 / 1, 1 / 2, 1 / 5, 1 / 10, or 1 / 20, etc., of the thickness of a single FRP layer or less. Each numerical value corresponds to a warpage standard value. Note that when the convex portion is a single layer, it can be considered symmetrically laminated with the center of the layer as the neutral axis. Although the case where warping does not occur in both the FRP layer 14 and the patch member 21 corresponding to the convex portion of the skin-to-skin fitting portion 33 has been described, warping may not occur in only a part of the FRP layer 14. It is preferable that warping does not occur in the thick plate portion having high rigidity.

[0038] ***Explanation of the Effects of Embodiment 4*** According to this embodiment, due to the improved fiber orientation, warping does not occur in the skin material 12, the patch member 21, or both, at the joint 31 of the sandwich panel structure 1 when the segment member 11 is segmented. Therefore, according to this embodiment, the sandwich panel structure 1 can be assembled relatively easily.

[0039] Fifth Embodiment Hereinafter, differences from the above-described embodiments will be mainly described with reference to the drawings.

[0040] ***Description of Configuration*** Figure 8 is a top view showing an example configuration of a sandwich panel structure 1 according to Embodiment 5. As shown in Figure 8, in Embodiment 5, the skin material 12 and the patch member 21 have concave and convex shapes that fit together. More specifically, in Figure 8, the skin material 12 and the patch member 21 each have a skin-patch fitting portion 35 where the skin material 12 and the patch member 21 fit together in a dovetail shape. The patch member 21 has the same shape in the thickness direction. In this example, the skin material 12 and the patch member 21 have the skin-patch fitting portion 35 where they fit together, thereby enabling a stronger bond between the skin material 12 and the patch member 21.

[0041] That is, the following holds true in this embodiment: A first uneven portion is formed on the first target skin material. A second uneven portion is formed on the patch member 21. In a target plane, which is a plane normal to the plate thickness direction, the first uneven portion has an uneven shape, and the second uneven portion has an uneven shape. When the first divided member and the second divided member are joined, the first uneven portion and the second uneven portion are fitted together. Furthermore, in the target plane, at least a portion of the sides of the first uneven portion do not extend along the longitudinal direction, and at least a portion of the sides of the second uneven portion do not extend along the longitudinal direction. Therefore, when the first uneven portion and the second uneven portion are fitted together, the first target skin material and the patch member 21 will not separate even if they are pulled in opposite directions along the longitudinal direction.

[0042] Although the case where the shape of the skin-patch fitting portion 35 is a dovetail joint has been described, the shape does not have to be a dovetail joint. Specific examples of the shape include a sickle joint and a dovetail joint. Furthermore, although the case where the patch member 21 has the same shape in the thickness direction has been described, the patch member 21 may have different shapes in the thickness direction.

[0043] ***Explanation of Effect of Embodiment 5*** According to this embodiment, the skin material 12 and the patch member 21 are joined in a fitted state at the joint 31. Therefore, according to this embodiment, the joint between the skin material 12 and the patch member 21 can be made stronger.

[0044] Sixth Embodiment Hereinafter, differences from the above-described embodiments will be mainly described with reference to the drawings.

[0045] ***Description of Manufacturing Method*** A specific example of a method for manufacturing a sandwich panel structure 1 according to the present disclosure will be described with reference to FIG. 9 . This manufacturing method corresponds to a method for manufacturing a sandwich panel structure. FIG. 9 is an explanatory diagram showing a specific example of a method for manufacturing a sandwich panel structure 1 according to Embodiment 6. Through steps 1 to 4, a sandwich panel structure 1 is produced, which is composed of segment members 11, patch members 21, and adhesive 22 disposed between the members. Here, a case will be described in which there are two segment members 11 in total, and the skin material 12 and patch members 21 are each made of FRP.

[0046] (Step 1: Member Molding Step) In this step, the divided member 11 and the patch member 21 are separately fabricated. FIG. 9A shows a cross-sectional view of the respective members after they have been separately fabricated. The divided member 11 is fabricated by fabricating the skin material 12 and then bonding and integrating the skin material 12 and the core material 13 using adhesive 22. Furthermore, when fabricating the skin material 12, the general shape of the groove portion 23 is formed by reducing the number of FRP layers in the joint portion 31 compared to the number of FRP layers in the non-joint portion 32. After this step, the surfaces of the skin material 12 and the patch member 21 are relatively smooth, reflecting the surface condition of the molding die. The member molding step also forms the first divided member, the second divided member, and the patch member 21.

[0047] (Step 2: Groove and Patch Member Processing Step) In this step, processing is performed on the groove portion 23 and the patch member 21. Figure 9(b) shows a cross-sectional view after groove processing. In the groove and patch member processing step, two processes are performed: shape processing and surface condition processing. In the shape processing, the portion that will become the groove portion 23, the rough shape of which was created in step 1, is machined to obtain the desired shape to address resin leakage and shape deviations caused by cure shrinkage and deformation. In the surface condition processing, the surfaces of the groove portion 23 and the patch member 21 are ground using abrasive paper to improve the adhesion between the groove portion 23 and the patch member 21. The process of forming the rough shape of the groove portion 23 and the process of processing the groove portion 23 in this step are collectively referred to as the groove processing step. The groove processing step is also a step of processing a first groove portion by thinning the thickness of the first target skin material in the thickness direction to an extent that the outer surface of the core material 13 of the first divided member is not exposed, and processing a second groove portion by thinning the thickness of the second target skin material in the thickness direction to an extent that the outer surface of the core material 13 of the second divided member is not exposed. The depth of the first groove portion is determined based on the sum of the thickness of the patch member 21 in the thickness direction and the thickness of the adhesive 22 disposed between the first groove portion and the patch member 21. The depth of the second groove portion is determined based on the sum of the thickness of the patch member 21 in the thickness direction and the thickness of the adhesive 22 disposed between the second groove portion and the patch member 21.

[0048] (Step 3: Placement Step) In this step, each component constituting the sandwich panel structure 1 is placed in the desired position. Figure 9(c) shows a cross-sectional view of the placement step. The arrows in Figure 9(c) indicate the movement direction of each component. The placement step will be described below in order. First, adhesive 22 is placed on the surfaces where the segment members 11 contact each other. Next, each segment member 11 is slid longitudinally to butt together. At this time, if a skin-to-skin fitting portion 33 is present, the segment members 11 are placed so that the uneven shapes on the left and right sides fit together. Here, since the segment members 11 are slid longitudinally, there is no need to lift the segment members 11. Next, adhesive 22 is placed in the groove portion 23 formed by the two segment members 11. Next, each patch member 21 is placed from the plate thickness direction of the sandwich panel structure 1. At this time, if a skin-to-patch fitting portion 35 is present, the uneven shapes of the skin material 12 and the patch member 21 are placed so that they fit together. The positioning step is also a step of positioning the first divided member, the second divided member, the patch member 21, and the adhesive 22 according to the shape of the sandwich panel structure 1. In the positioning step, the first divided member and the second divided member may be joined by moving each of them in the direction normal to the joining surface between the first divided member and the second divided member when the first divided member and the second divided member are joined together.

[0049] (Step 4: Integration Step) In this step, the components constituting the sandwich panel structure 1, which were arranged in the desired positions in the arrangement step, are integrated. Figure 9(d) shows a cross-sectional view after integration. In the integration step, the components constituting the sandwich panel structure 1 are integrated by curing the adhesive 22 at the joints 31. One curing method involves covering the surfaces of the joints 31 with a rubber heater (not shown) and applying electricity to the rubber heater to heat the rubber heater, thereby thermally curing the adhesive 22. When using the rubber heater for heating, placing a weight (not shown) on a surface of the rubber heater other than the surface that contacts the sandwich panel structure 1 can reduce the gap between the patch member 21 and the skin material 12, resulting in a stronger bond. The integration step also integrates the first divided member, the second divided member, and the patch member 21 by curing the adhesive 22.

[0050] In step 1, the divided member 11 is fabricated by fabricating the skin material 12 and then integrating the skin material 12 and the core material 13 using the adhesive 22. However, the skin material 12 may be placed on the core material 13, and the molding of the skin material 12 and the integration of the skin material 12 and the core material 13 may be performed simultaneously. In this case, the adhesive 22 may be placed between the skin material 12 and the core material 13. Although the grooves 23 are generally formed in step 1, they may not necessarily be formed in step 1. If the grooves 23 are not generally formed in step 1, they are formed in the shaping process in step 2. Although grinding using abrasive paper is described as the surface conditioning process, this process does not have to be grinding using abrasive paper. Specific examples of surface conditioning processes include grinding using an abrasive cloth, a wire brush, sandblasting, or the like. In addition to or instead of grinding, chemical treatment, primer treatment, ultraviolet irradiation treatment, plasma treatment, or the like may also be performed in the surface conditioning process. In addition, although a rubber heater is used for heating in step 4, heating may be performed without using a rubber heater. Specific examples of heating methods include a method using an IR (infrared) heater, a heat gun, or an oven. In addition, although a weight is used to reduce the gap that occurs between the patch member 21 and the skin material 12 in step 4, a method that does not use a weight may be used to reduce the gap. Specific examples of such methods include clamping using a vice or local bagging.

[0051] ***Explanation of Effects of Sixth Embodiment*** According to this embodiment, the sandwich panel structure 1 can be assembled relatively easily.

[0052] ***Other Embodiments*** The above-described embodiments can be freely combined, or any of the components of each embodiment can be modified, or any of the components can be omitted from each embodiment. Furthermore, the embodiments are not limited to those shown in embodiments 1 to 6, and various modifications are possible as needed.

[0053] 1 sandwich panel structure, 11 dividing member, 12 skin material, 13 core material, 14, 14a, 14b, 14c, 14d, 14e, 14f, 14g FRP layer, 21 patch member, 22 adhesive, 23 groove portion, 31 joint portion, 32 non-joint portion, 33 skin-skin fitting portion, 34 dividing surface, 35 skin-patch fitting portion.

Claims

1. In a sandwich panel structure made up of a plurality of divided members, each divided member of the plurality of divided members is a first divided member, and the first divided member is joined to a second divided member of the plurality of divided members, the first divided member includes two skin materials and a core material disposed between the two skin materials, one of the two skin materials being a first target skin material; At a joint portion of the first divided member where the first divided member is joined to the second divided member, the first target skin material has a groove portion formed by reducing the thickness of the first target skin material to an extent that the outer surface of the core material is not exposed, In a state in which the first divided member and the second divided member are joined together, a patch member is disposed in the groove portion via an adhesive; A sandwich panel structure in which, at the boundary between the joint and the non-joint portion, which is a portion of the first divided member other than the joint, the total thickness in the plate thickness direction of the first target skin material, the adhesive, and the patch member at the joint and the thickness in the plate thickness direction of the first target skin material at the non-joint portion are the same or change continuously.

2. a depth of the groove in the thickness direction is equal to a sum of a thickness of the patch member in the thickness direction and a thickness of the adhesive in the thickness direction; The sandwich panel structure according to claim 1 , wherein the adhesive is disposed between the first divided member and the patch member.

3. 3. The sandwich panel structure according to claim 1, wherein at least one of the first target skin material and the patch member is made of fiber-reinforced plastic.

4. each of the patch member and the first target skin material is made of fiber-reinforced plastic; 3. The sandwich panel structure according to claim 1, wherein the patch member has a fiber content greater than the fiber content of the first target skin material.

5. a recess is formed in the first target skin material at the joint; a second target skin material provided on the second divided member at a portion of the second divided member that is joined to the first divided member, the second target skin material being a skin material that faces the first target skin material when the first divided member and the second divided member are joined together, has a convex portion formed on it; 3. The sandwich panel structure according to claim 1, wherein the recess and the protrusion are fitted together when the first divided member and the second divided member are joined together.

6. the recess is formed on a joining surface where the first divided member and the second divided member are joined, The depth direction of the recess is the longitudinal direction of the sandwich panel structure, the protrusion is formed on the joining surface, The sandwich panel structure according to claim 5 , wherein the height direction of the protrusion is the longitudinal direction.

7. each of the first target skin material and the second target skin material is made of fiber-reinforced plastic; 6. The sandwich panel structure according to claim 5, wherein each of the recessed portion and the protruding portion is formed of a layer of fiber-reinforced plastic.

8. each of the first target skin material and the second target skin material is made of fiber-reinforced plastic; The sandwich panel structure according to claim 5, wherein the layers of the convex portion are symmetrically laminated.

9. each of the first target skin material and the second target skin material is made of fiber-reinforced plastic; The materials of the layers of the protrusions are not all the same, The layer of the convex portion is asymmetrically laminated, The sandwich panel structure according to claim 5 , wherein the protrusions do not warp in the thickness direction of the panel due to thermal deformation beyond a standard warp value.

10. a first uneven portion is formed on the first target skin material; a second uneven portion is formed on the patch member; In a target plane which is a plane having a normal line in the plate thickness direction, the shape of the first uneven portion is an uneven shape, and the shape of the second uneven portion is an uneven shape, 3. The sandwich panel structure according to claim 1, wherein the first concave-convex portion and the second concave-convex portion are fitted together when the first divided member and the second divided member are joined together.

11. In the target plane, at least a part of the side of the first uneven portion does not follow the longitudinal direction of the sandwich panel structure, and at least a part of the side of the second uneven portion does not follow the longitudinal direction, 11. The sandwich panel structure according to claim 10, wherein when the first uneven portion and the second uneven portion are fitted together, the first target skin material and the patch member do not separate even when they are pulled in opposite directions along the longitudinal direction.

12. 3. The sandwich panel structure according to claim 1, wherein the first target skin material and the patch member are made of the same material.

13. 3. The sandwich panel structure according to claim 1, wherein the thickness of the first target skin material in the plate thickness direction varies continuously from the joint portion to the non-joint portion along the longitudinal direction of the sandwich panel structure.

14. 3. The sandwich panel structure according to claim 1, wherein the material constituting the first target skin material is continuous along the longitudinal direction of the sandwich panel structure at the boundary between the joint portion and the non-joint portion.

15. A method for manufacturing a sandwich panel structure, comprising: a first divided member and a second divided member, each of which is made up of two skin materials and a core material disposed between the two skin materials; a patch member; and an adhesive, When one of the two skin materials of the first divided member is defined as a first target skin material, and one of the two skin materials of the second divided member that faces the first target skin material when the first divided member and the second divided member are joined together is defined as a second target skin material, a member molding step of molding each of the first divided member, the second divided member, and the patch member; a groove processing step of processing a first groove portion by reducing the thickness of the first target skin material in the thickness direction within a range in which the outer surface of the core material of the first divided member is not exposed, and processing a second groove portion by reducing the thickness of the second target skin material in the thickness direction within a range in which the outer surface of the core material of the second divided member is not exposed; an arrangement step of arranging the first divided member, the second divided member, the patch member, and the adhesive according to the shape of the sandwich panel structure; an integration step of integrating the first divided member, the second divided member, and the patch member by hardening the adhesive; A method for manufacturing a sandwich panel structure, comprising: a depth of the first groove portion is determined according to a sum of a thickness of the patch member in the thickness direction and a thickness of an adhesive disposed between the first groove portion and the patch member in the thickness direction, a depth of the second groove portion that is determined according to the sum of the thickness of the patch member in the plate thickness direction and the thickness of the adhesive disposed between the second groove portion and the patch member in the plate thickness direction.

16. 16. The method for manufacturing a sandwich panel structure according to claim 15, wherein in the positioning step, the first divided member and the second divided member are joined by moving each of the first divided member and the second divided member in a direction normal to the joining surface between the first divided member and the second divided member when the first divided member and the second divided member are joined.