Panel

Abstract

To provide a panel capable of improving impact resistance.SOLUTION: According to the present invention, there is provided a panel comprising a core material and a first face material and a second face material, wherein the core material is sandwiched between the first face material and the second face material, the first face material and the second face material are bonded to the core material, the second face material includes one or more deformation-promoting portions that promote plastic tensile deformation of the second face material, and the panel is supported on the second face material side by a plurality of support portions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a panel that can be used as a deck board or the like to be installed in a luggage compartment of a vehicle. [Background technology]

[0002] Patent Document 1 discloses a panel that includes a core material and first and second face materials, with the first face material being thicker than the second face material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-175421 Summary of the Invention [Problem to be solved by the invention]

[0004] In panels such as that disclosed in Patent Document 1, the second face material is made thinner than the first face material, thereby suppressing an increase in panel weight while ensuring impact resistance, but further improvements in impact resistance are desired.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a panel that can improve impact resistance. [Means for solving the problem]

[0006] According to the present invention, the following inventions are provided. [1] A panel comprising a core material, a first face material, and a second face material, wherein the core material is sandwiched between the first face material and the second face material, the first face material and the second face material are joined to the core material, the second face material has one or more deformation promoting portions that promote plastic tensile deformation of the second face material, and the panel is supported by a plurality of supporting portions on the second face material side. [2] A panel as described in [1], wherein the plurality of support portions are arranged along the periphery of the panel, and at least a portion of the deformation promoting portions are arranged within a distance from a center line passing through an area of ​​the panel where bending stress is concentrated, in a direction perpendicular to the center line, of 10.0% of the maximum length of the panel in the perpendicular direction. [3] A panel according to [2], wherein the ratio wtotal / W of the total length wtotal of the one or more deformation promoting portions in a direction parallel to the central straight line to the maximum length W of the panel in the parallel direction is 0.011 to 0.078. [4] A panel according to [3], wherein the ratio li / L of the length li of each of the one or more deformation promoting portions in a direction perpendicular to the central straight line to the maximum length L of the panel in the perpendicular direction is 0.020 to 0.420. [5] The panel according to any one of [1] to [4], wherein the panel has an opening. [6] A panel according to [5], wherein some of the one or more deformation promoting portions are provided along the periphery of the opening. [Effects of the Invention]

[0007] The inventors have conducted extensive research to improve the impact resistance of panels, and have found that in a panel in which a core material is sandwiched between a first panel and a second panel, and the first panel and the second panel are joined to the core material, and the panel is supported by a plurality of support portions on the second panel side, by providing one or more deformation-promoting portions that promote plastic tensile deformation of the second panel around a central line that passes through the area of ​​the panel where bending stress is concentrated, it is possible to suppress buckling deformation of the first panel and improve the impact resistance of the panel, which led to the completion of the present invention. [Brief explanation of the drawings]

[0008] [Figure 1]FIG. 1A is a diagram showing the planar shape of a panel 1 placed on a support in the first embodiment, FIG. 1B is a side view of the panel 1 of FIG. 1A with a box 9 placed thereon, FIG. 1C is an enlarged view of area C of FIG. 1B, and FIG. 1D is an enlarged view showing the components of FIG. 1C and their upper and lower edges. [Figure 2] FIG. 2A is a diagram showing the planar shape of panel 1 supported by support portions 5a to 5d arranged inside the peripheral edge of panel 1, and FIG. 2B is a plan view showing details of deformation promoting portions 6a and 6b provided in second face material 4 of panel 1. [Figure 3] Figure 3A is a plan view showing deformation promoting portions 6a to 6c arranged around the central straight line 12 of panel 1, Figure 3B is a plan view showing details of deformation promoting portions 6a to 6c of Figure 3A, and Figure 3C is a plan view showing a cross section for measuring the width of deformation promoting portions 6a to 6c of Figure 3A. [Figure 4] FIG. 4 is a diagram showing the planar shape of the panel 1 having the openings 7a and 7b. [Figure 5] Figure 5A is a diagram showing the planar shape of a second surface material 4 having deformation-promoting portions 6a and 6b, Figure 5B is an enlarged view of region B in Figure 5A when the deformation-promoting portions 6a and 6b are cutouts 61, and Figure 5C is an enlarged view of region B in Figure 5A when the deformation-promoting portions 6a and 6b include multiple slits 62. [Figure 6] FIG. 6 is a diagram showing the planar shapes of the panel 1 and the supporting portions 5a to 5d of the second embodiment. [Figure 7] FIG. 7 is a diagram showing the planar shapes of the panel 1 and supporting portions 5a to 5f of the third embodiment. [Figure 8] FIG. 8 is a diagram showing the planar shapes of the panel 1 and the supporting portions 5a to 5n of the fourth embodiment. [Figure 9] FIG. 9A is a diagram showing the planar shape of a core material 2 having a recess 8a and a small recess 8b, FIG. 9B is a cross-sectional view showing section BB of FIG. 9A, and FIG. 9C is an enlarged view of area C of FIG. 9B. [Figure 10]Figure 10A shows the model used in the impact resistance analysis, Figure 10B shows an example of the mesh of panel 1 in the impact resistance analysis, and Figure 10C shows an example of the mesh of second face material 4 when a cutout is present. [Figure 11] FIG. 11A is a diagram showing the results of an impact analysis when there is no notch (deformation promoting portion), and FIG. 11B is a diagram showing the results of an impact analysis when there is a notch (deformation promoting portion). DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an invention independently. Furthermore, in the following embodiments, elements not specified in the claims are optional elements and can be omitted. Any number of "0"s (for example, one or two) may be added to the end of numerical values ​​disclosed in the following description. For example, one or two "0"s may be added after "1.4" to make it "1.40" or "1.400."

[0010] 1. First embodiment 1-1. Structure of Panel 1 As shown in Fig. 1A, panel 1 in the first embodiment is a panel having a pair of opposing long sides and a pair of opposing short sides in a planar shape, and is supported by support portions 5a and 5b arranged on the second face member 4 side along the short sides. Furthermore, deformation promoting portions 6a and 6b are provided in the second face member 4 at the center portion along the long sides. The planar shape refers to the shape of panel 1 and the components of panel 1 when panel 1 is viewed from a direction perpendicular to the upper edge of panel 1 (i.e., upper edge 3a of first face member 3) or the lower edge of panel 1 (i.e., lower edge 4b ​​of second face member 4), as shown in Fig. 1A, for example.

[0011] If the lengths of the long and short sides are L1 and L2, respectively (i.e., L1≧L2), L1 is, for example, 700 mm to 1100 mm, preferably 800 mm to 1000 mm, and specifically, for example, 700, 800, 900, 1000, or 1100 mm, or may be within a range between any two of the numerical values ​​exemplified here. Similarly, L2 is, for example, 235 mm to 635 mm, preferably 335 mm to 535 mm, and specifically, for example, 235, 300, 335, 400, 435, 500, 535, 600, or 635 mm, or may be within a range between any two of the numerical values ​​exemplified here. Furthermore, the value of L2 / L1 is, for example, 0.20 to 1.0, and is preferably 0.33 to 0.67, and specifically, for example, 0.20, 0.25, 0.30, 0.33, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.67, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.0, and may be within a range between any two of the numerical values ​​exemplified here.

[0012] 1B, a load (e.g., a box 9) is placed on the upper edge of panel 1. This causes panel 1 to bend (flex) convexly in the direction of arrow z, while supporting the load of box 9.

[0013] As shown in Figures 1C and 1D, panel 1 has a structure in which core material 2 and first face material 3 are joined, and further core material 2 is joined to second face material 4. From the viewpoint of reducing the weight of panel 1, the weight per unit area of ​​panel 1 excluding deformation promoting portions 6a and 6b (for example, per unit area of ​​the upper edge of panel 1) is set to 3700 g / m 2 Preferably less than 3100 g / m 2 Less than 2100 g / m is more preferable. 2 More preferably, the weight is, for example, 1900 to 3700 g / m 2 Specifically, for example, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700 g / m 2and may be within a range between any two of the numerical values ​​exemplified here or equal to or less than any of them.

[0014] The core material 2 is preferably a plate-shaped member. The thickness of the core material 2 is, for example, 15 to 25 mm, preferably 18 to 22 mm. If the core material 2 is too thin, the overall deflection of the panel 1 may be too large. On the other hand, if the core material 2 is too thick, the weight of the panel 1 may be too large. Specific examples of the thickness are 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25 mm, and may be within a range between any two of the values ​​exemplified here. The thickness of the core material 2 refers to the distance between the opposing upper edge 2a and lower edge 2b of the core material 2 (the distance in the normal direction of the upper edge or lower edge) at the location where the distance is greatest. As shown in FIG. 1D, the upper edge 2a and lower edge 2b of the core material 2 are the surfaces that are joined to the first face material 3 and the second face material 4, respectively.

[0015] Preferably, a recess 8a (FIG. 9) is provided in the core material 2, and the first face material 3 and the second face material 4 can be fixed in the recess. This prevents the first face material 3 and the second face material 4 from peeling off from the core material 2. In this case, the thickness of the core material 2 is determined by the thickness at the recess 8a.

[0016] The core material 2 may be a foam or a non-foam. Examples of foams include expanded polystyrene (EPS), expanded acrylonitrile styrene (EAS), and expanded polypropylene (EPP). An example of a non-foam is a honeycomb core, which may be made from metal (e.g., aluminum), resin, or paper (including special paper such as aluminum hydroxide paper, and paper and special paper impregnated with resin and fire retardant). Using a foam or honeycomb core makes the core material 2 lighter and more rigid, thereby reducing the weight of the panel 1 and suppressing buckling deformation.

[0017] The density (apparent density including bubbles) and rigidity of the foam material are affected by the expansion ratio. When the expansion ratio is high, the resin material contains many bubbles, resulting in a decrease in apparent density and rigidity. On the other hand, when the expansion ratio is low, the apparent density and rigidity are improved. The expansion ratio of the core material 2 is, for example, 20 to 50 times to strike a balance between reducing the weight of the panel 1 and suppressing buckling deformation, and specifically may be, for example, 20, 25, 30, 35, 40, 45, or 50 times, or may be within a range between any two of the values ​​exemplified here. Foams having such expansion ratios can be produced, for example, by bead expansion molding.

[0018] The core material 2 may be hollow or solid. When the core material 2 is hollow, it is preferable that the vicinity of the neutral plane (a plane where no stress or strain occurs due to bending) when the panel 1 is bent and deformed is hollow, for example.

[0019] The rigidity of the core material 2 is evaluated, for example, by the magnitude of the compressive stress (10% compressive stress) required to generate a 10% compressive strain in the core material 2. The 10% compressive stress of the core material 2 is, for example, 0.05 to 1.0 MPa, and preferably 0.1 to 0.5 MPa. If this value is too small, buckling deformation of the panel 1 is likely to occur, while if this value is too large, the weight of the panel 1 is likely to be excessive. Specific examples of this value are 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, and 1.00 MPa, and may be within a range between any two of the values ​​exemplified here. The 10% compressive stress of the core material 2 can be measured in accordance with JIS K 7220.

[0020] The following formula 1 is the buckling stress σ of a rectangular plate material when a uniform compressive load acts on two opposing sides. cris the formula for calculating the buckling coefficient, where k is the buckling coefficient, E is Young's modulus (also known as the tensile modulus of elasticity), π is the constant of the circumference of the plate, ν is Poisson's ratio, t is the thickness of the plate, and b is the width of the plate (where a is the length of the plate, and a ≧ b). The buckling coefficient k is determined depending on the aspect ratio (a / b) of the plate and the support form (e.g., simple support on all four sides) (for example, for a plate with a / b=2 and simply supported on all four sides, k ≒ 4).

[0021]

number

[0022] As shown in Equation 1, the buckling stress of a plate increases as the plate's rigidity (Young's modulus) increases. On the other hand, the bending compressive stress acting on the plate will not increase unless the bending moment (which depends on the magnitude and position of the external force acting perpendicular to the surface of the plate) or the plate's second moment of area (which depends on the cross-sectional shape) changes. In other words, using a material with high rigidity is effective in suppressing buckling deformation, as it reduces the value of [bending compressive stress / buckling stress].

[0023] Equation 1 also shows that the buckling stress σ can be increased by increasing the plate thickness t and / or decreasing the plate width b. cr indicates that the thickness increases. Since an increase in thickness may lead to an increase in panel weight, and a decrease in width may lead to a decrease in panel area on which a load can be placed, it is preferable to change these values ​​taking into consideration the effects on, for example, panel weight and area.

[0024] In the case of a panel 1 that is supported on the second face material 4 side and has a load acting on the first face material 3 side, as in this embodiment, it is assumed that compressive stress due to bending acts on the first face material 3, and tensile stress due to bending acts on the second face material 4. It is assumed that compressive stress and tensile stress due to bending act simultaneously on the core material 2 across the neutral plane.

[0025] Therefore, it is preferable that the panel 1 has the ability to suppress buckling deformation due to compression of the first face material 3, and also has the ability to lead to weight reduction of the panel 1. Furthermore, it is preferable that the panel 1 has the ability to suppress breakage such as brittle shattering when subjected to an impact load (e.g., a dynamic load acting when the box 9 is dropped from a certain height). Hereinafter, the ability to suppress buckling deformation (and breakage due to impact) will be referred to as "impact resistance."

[0026] An example of a material that satisfies the requirements for impact resistance and light weight is aluminum (e.g., AL5052). Aluminum is softer and lighter than iron (including steel, alloy steel, etc.), so it has the advantage of being less likely to break into brittle pieces when subjected to impact and also contributing to lighter weight. Aluminum is particularly preferred as a material for the first surface material 3, and is also preferred as a material for the second surface material 4, for example.

[0027] Iron (including steel, alloy steel, etc.) is also a preferred material for the second surface material 4. Since tensile stress is expected to act on the second surface material 4, it is not necessary to increase the thickness of the material to suppress buckling deformation. If the thickness of the second surface material 4 can be reduced, the disadvantage of the heavy weight of iron is reduced, and the advantage of lower cost than aluminum for the same weight becomes greater.

[0028] The material of the first face material 3 and the second face material 4 may be, for example, a resin with high impact resistance (for example, a resin impregnated with glass fiber (GF)).

[0029] The first and second face materials 3 and 4 are preferably plate-shaped. To prevent buckling deformation, the thickness of the first face material 3 is preferably greater than that of the second face material 4. However, the first and second face materials 3 and 4 may be the same thickness, which allows for the use of the same raw material, simplifying manufacturing equipment and reducing costs. The term "thickness" here refers to the maximum length of a straight line connecting the upper and lower edges of the face material along the normal to the upper or lower edge. The lower edge 3b of the first face material 3 is the surface that is joined to the core material 2, and the upper edge 3a of the first face material 3 is the surface opposite the lower edge. The upper edge 4a of the second face material 4 is the surface that is joined to the core material 2, and the lower edge 4b ​​of the second face material 4 is the surface opposite the upper edge. If the face material has protrusions such as ribs, the thickness is calculated without including these protrusions.

[0030] The thickness of the first face material 3 is, for example, 0.30 mm to 1.00 mm, specifically, for example, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, or 1.00 mm, or may be within a range between any two of the values ​​exemplified here. The thickness of the second face material 4 is, for example, 0.10 mm to 0.30 mm, specifically, for example, 0.10, 0.15, 0.20, 0.25, or 0.30 mm, or may be within a range between any two of the values ​​exemplified here. Furthermore, the value of [thickness of first face material / thickness of second face material] is preferably 1.5 or greater. This value is, for example, 1.5 to 10.0, and specifically, for example, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, and may be within a range between any two of the numerical values ​​exemplified here.

[0031] The Young's modulus of the first face material 3 and the second face material 4 (Young's modulus in the direction along the fibers when fibers such as fiber-reinforced resin are included) is, for example, 2 to 300 GPa, and preferably 50 to 250 GPa, from the viewpoint of suppressing buckling deformation (first face material 3) and excessive deflection (second face material 4). Specific examples of this Young's modulus include 2, 3, 4, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, and 300 GPa, and may be within a range between any two of the values ​​exemplified here.

[0032] The second panel 4 is provided with deformation promoting portions 6a and 6b for promoting plastic deformation of the second panel 4 by concentrating the tensile stress generated during bending deformation of the panel 1. For example, the deformation promoting portions 6a and 6b locally reduce the cross-sectional area of ​​the second panel 4, causing stress concentration of the bending tensile stress and inducing plastic deformation.

[0033] There is a minimum thickness for face materials available on the market (for example, 0.20 mm for aluminum face materials), and reducing the thickness beyond this requires special production methods or additional processing, which poses a cost issue. On the other hand, reducing the length or width of face materials may also require additional processing, but in that case, inexpensive processing methods such as punching can be applied, which is considered more preferable from a cost perspective.

[0034] Panel 1 is supported from the side of second face material 4 by support portions 5a and 5b arranged along the periphery of panel 1. Although support portions 5a and 5b are arranged along the periphery of panel 1, this does not necessarily mean that support portions 5a and 5b are arranged so as to contact the periphery of panel 1; support portions 5a and 5b may contact panel 1 inside the periphery. Support portions 5a and 5b may be arranged at any position along the periphery of panel 1, as long as the support portions are arranged such that when panel 1 is placed on them, balance of forces and balance of moments are satisfied and panel 1 comes to rest.

[0035] The deformation promoting portions 6a and 6b are preferably arranged around a central straight line 12 of the panel 1. The central straight line 12 is determined as follows. First, the peripheral edge of the panel 1 that exists between two adjacent support portions in the distance along the peripheral edge of the panel 1 is referred to as the peripheral section, and the peripheral section that is the longest in the distance along the peripheral edge of the panel 1 among the peripheral sections is referred to as the longest peripheral section. Furthermore, the point along the peripheral edge of the panel 1 that bisects the distance of the longest peripheral section is defined as the midpoint. Second, of any two pairs of parallel lines that are tangent to (but do not intersect with) the peripheral edge of the panel 1 on either side of the panel 1, the direction in which the distance between the two pairs of parallel lines (i.e., the distance in the direction perpendicular to the two pairs of parallel lines) extends is defined as the first main direction of the panel 1, and the direction perpendicular to that direction is defined as the second main direction of the panel 1. The first and second main directions of panel 1 are indicated by arrows x and y in Fig. 1A, respectively, and these directions are applicable to definitions other than the central line 12. Third, among the lines that pass through the center point of the longest peripheral section and are parallel to the first or second main direction of panel 1, the line that most closely bisects the area of ​​panel 1 in its planar shape is defined as the central line 12 of panel 1.

[0036] The longest peripheral section (peripheral sections 10a and 10b), center points 11a and 11b, and center line 12 of panel 1 in this embodiment are shown in FIG. 1A.

[0037] If multiple center lines 12 can be defined, for example because there are multiple longest peripheral sections, the line that most closely bisects the area of ​​the panel 1 in its planar shape is defined as the center line 12 of the panel 1. If multiple center lines 12 can still be defined, all of them will be adopted as the center lines 12. Furthermore, for example, in a panel whose planar shape is circular, if the first and second main directions cannot be defined (i.e., any direction can be defined as the first and second main directions), the line that passes through the center point and bisects the area of ​​the panel 1 in its planar shape is defined as the center line 12 of the panel 1.

[0038] As shown in FIG. 2A, when the support portions 5a-5d are in contact with the panel 1 inside the periphery of the panel 1 (i.e., when the support portions 5a-5d do not intersect or contact the periphery of the panel 1 in planar form), the peripheral section of the panel 1 is defined as a section defined by a point where a line passing through the center of gravity G of the panel 1 in planar form and tangent to (but not intersecting with) the outer periphery of each of the support portions 5a-5d intersects with the periphery of the panel 1, and the section does not include the support portions 5a-5d. For example, in the case of the panel 1 and support portions 5a-5d shown in FIG. 2A, the panel 1 has peripheral sections 10a-10d, of which the peripheral sections 10a and 10b are the longest. The line passing through either of the center points 11a and 11b and parallel to the second main direction of the panel 1 is the central line 12 of the panel 1.

[0039] When a load (e.g., box 9) is placed on panel 1 (e.g., FIG. 1B), the bending stress of panel 1 is thought to be greatest around center line 12. Deformation promoting portions 6a and 6b are configured to be arranged around the center line to promote plastic deformation of second panel 4 and suppress buckling deformation of panel 1.

[0040] As shown in FIG. 2B, the deformation promoting portions 6a and 6b do not necessarily have to be arranged along the periphery of the panel 1 and / or the centers of gravity G1 and G2 of the deformation promoting portions 6a and 6b in the planar shape do not necessarily have to be arranged on the center line 12 and / or be arranged symmetrically with respect to the center line 12. As shown in FIG. 3A, it is sufficient that at least a portion of the deformation promoting portions 6a to 6c are within a certain distance from the center line 12 in the direction perpendicular to the center line 12 (for example, within m% of the maximum length L of the panel 1 in the perpendicular direction). In such an arrangement (for example, FIG. 3A), the deformation promoting portions 6a to 6c are arranged around the center line 12. The value of m is, for example, 10.0%, preferably 5.0%, and more preferably 2.5%. Specific examples of the value of m are 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, and 10.0%.

[0041] As shown in FIG. 3B, the length l of each deformation promoting portion in the direction perpendicular to the central straight line 12 i (i=1, 2, ..., N; N represents the total number of deformation promoting portions) is, for example, 20 mm to 420 mm, and preferably 120 mm to 320 mm. This value is specifically, for example, 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 420 mm, and may be within a range between any two of the values ​​exemplified here. Furthermore, the length l i The ratio l of the maximum length L of panel 1 in the direction perpendicular to the central line 12 to i The value of / L is, for example, 0.020 to 0.420, and preferably 0.120 to 0.320. Specific examples of this value include 0.020, 0.040, 0.060, 0.080, 0.100, 0.120, 0.140, 0.160, 0.180, 0.200, 0.220, 0.240, 0.260, 0.280, 0.300, 0.320, 0.340, 0.360, 0.380, 0.400, and 0.420, and may be within a range between any two of the values ​​exemplified here.

[0042] As shown in FIG. 3B, the sum of the lengths (i.e., widths) of the deformation promoting portions 6a to 6c in the direction parallel to the center line 12 is w total (w total The width (the detailed definition of which will be explained in the following paragraphs) is, for example, 5 mm to 35 mm, and preferably 15 mm to 25 mm. Specific examples of this value include 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, and 35 mm, and may be within a range between any two of the values ​​exemplified here. Furthermore, the ratio w of the sum of the widths of the deformation promoting portions 6a to 6c to the maximum length (i.e., maximum width) W of the panel 1 in the direction parallel to the central straight line 12 is total The value of / W is, for example, 0.011 to 0.078, and is preferably 0.033 to 0.056. Specifically, this value is, for example, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.020, 0.021, 0.022, 0.023, 0.024, 0.025, 0.026, 0.027, 0.028, 0.029, 0.030, 0.031, 0.032, 0.033, 0.034, 0.035, 0.036, 0.037, 0.038, 0.039, 0.040, 0.041, 0.042, 0.043, 0.044, 0.045, 0.0 0.070, 0.071, 0.072, 0.073, 0.074, 0.075, 0.076, 0.077, 0.078, and may be within a range between any two of the numerical values ​​exemplified here.

[0043] w totalThe value of is adopted as the value in the cross section along the central straight line 12 where the ratio of the total width of the deformation promoting portion to the maximum width W of the panel 1 is the largest. For example, in the example shown in FIG. 3C, among cross sections AA, BB, and CC, w total = Use the value w1+w2+w3.

[0044] Furthermore, as shown in Figure 4, total If the cross-sectional view in which the value of is calculated includes the openings 7a and 7b of the panel 1, W' is calculated by subtracting the total width of the openings 7a and 7b from the maximum width W of the panel 1 (in the example of Figure 4, W' = Ww o1 -w o2 ) and w total Calculate the value of / W' and set it to w total This will be used instead of the value of / W.

[0045] In the panel 1 of this embodiment, the length L1 corresponds to the maximum length L of the panel 1, and the length L2 corresponds to the maximum length W (maximum width W) of the panel 1.

[0046] As shown in FIG. 5, the deformation promoting portions 6a and 6b may be, for example, a cutout 61 throughout, or may be a region including multiple slits 62. The shape of the slits may be, for example, a long, narrow rectangle with rounded corners as shown in FIG. 5B-2, or may be a circle, ellipse, triangle, quadrangle (square, rectangle, trapezoid), other polygon, or a combination thereof. The deformation promoting portions 6a and 6b may also be a region including a hole having such a shape. Furthermore, the deformation promoting portions 6a and 6b may be, for example, a region of the upper edge 4a of the second face material 4 that is not joined to the core material 2 in the planar shape of the panel 1.

[0047] When the deformation promoting portion 6a is an area including a plurality of slits 62, the area surrounded by the shortest line among any lines that surround all of the plurality of slits 62 in the planar shape of the panel 1 as shown in FIG. 5B-2 is the deformation promoting portion. totalWhen calculating the value of w, each slit in the second face material 4 is regarded as a deformation promoting portion, and total According to the calculation method of w total The value of is calculated and used. In the planar shape shown in FIG. 5B-2, the ratio of the area of ​​the deformation promoting portions to the total area of ​​the slits 62 is, for example, 10% or more, and preferably 30% or more. Specific examples of this value are 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100%, and may be within a range between any two of the values ​​exemplified here (in the case of 100%, the deformation promoting portions are notches). The matters described in this paragraph above also apply when the deformation promoting portions 6a and 6b are regions including multiple holes (instead of slits 62).

[0048] The planar shape of the deformation promoting portion may be a rectangle as shown in FIG. 5, or may be, for example, a circle, an ellipse, a triangle, a quadrangle (square, rectangle, trapezoid), another polygon, or a combination thereof.

[0049] The core material 2 and the first surface material 3 and the core material 2 and the second surface material 4 may be bonded together using an adhesive. Examples of adhesives include urethane-based adhesives and olefin-based adhesives, with one-component reactive urethane-based adhesives being preferred. The thickness of the adhesive layer is, for example, 0.01 to 0.5 mm, specifically, for example, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, or 0.5 mm, and may be within a range between any two of the values ​​exemplified here. The "thickness" here refers to the maximum length of a straight line connecting the upper and lower edges of the adhesive layer along the normal direction of the upper or lower edge of the adhesive layer. For example, in the case of an adhesive layer between the core material 2 and the first surface material 3, the upper edge of the adhesive layer refers to the surface that contacts the first surface material 3, and the lower edge of the adhesive layer refers to the surface that contacts the core material 2. In the adhesive layer between the core material 2 and the second surface material 4, the surface in contact with the core material 2 is the upper edge, and the surface in contact with the second surface material 4 is the lower edge. Note that if localized convex portions are formed in the adhesive layer due to the provision of concave portions in the first surface material 3 or the second surface material 4, the thickness of the adhesive layer shall be calculated without including such convex portions.

[0050] 1-2. Manufacturing method of panel 1 The panel 1 can be manufactured, for example, by applying adhesive (eg, spray coating or bead coating) onto the core material 2 and then pressing the first and second facing materials 3 and 4 onto the core material 2 .

[0051] 2. Second embodiment 2-1. Structure of Panel 1 The structure of the panel 1 of the second embodiment shown in Figure 6 differs from the structure of the panel 1 of the first embodiment in the shape of the panel 1, the number and arrangement of the support parts, and the arrangement of the deformation promoting parts, but the other features are the same as those of the panel 1 of the first embodiment.

[0052] The panel 1 is supported on the second face material 4 side of the panel 1 by support parts 5a to 5d, but since no support parts are located on the periphery that is located inside the pair of ends of the longest peripheral section 10a (or 10b) in the distance perpendicular to the central line 12 and that faces the longest peripheral section 10a (or 10b), it can be considered that the panel 1 is essentially supported on two sides by support parts 5a and support parts 5b to 5d.

[0053] The maximum length L of the panel 1, i.e., the maximum length of the panel 1 in the direction perpendicular to the central straight line 12, is, for example, 600 mm to 1000 mm, specifically, for example, 600, 650, 700, 750, 800, 850, 900, 950, or 1000 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0054] The maximum width W of the panel 1, i.e., the maximum length of the panel 1 in the direction parallel to the central straight line 12, is, for example, 800 mm to 1200 mm, and specifically, for example, 800, 850, 900, 950, 1000, 1050, 1100, 1150, or 1200 mm, or may be within a range between any two of the values ​​exemplified here. The first and second main directions of the panel 1 are indicated by arrows x and y, respectively, in FIG. 6.

[0055] 2-2. Manufacturing method of panel 1 The manufacturing method of the panel 1 of the second embodiment may be the same as that of the panel 1 of the first embodiment.

[0056] 3. Third embodiment 3-1. Structure of Panel 1 The structure of the panel 1 of the third embodiment shown in Figure 7 differs from the structure of the panel 1 of the first embodiment in the shape of the panel 1, the number and arrangement of the support parts, and the arrangement of the deformation promoting parts, but the other features are the same as those of the panel 1 of the first embodiment.

[0057] The panel 1 is supported on the second face material 4 side of the panel 1 by support portions 5a to 5f, and support portions 5c and 5d are arranged on the periphery that is located more inward than the pair of ends of the longest peripheral section 10a in the distance perpendicular to the central line 12 and that faces the longest peripheral section 10a. Therefore, the panel 1 can be considered to be supported on three sides by support portions 5a and 5b, support portions 5c and 5d, and support portions 5e and 5f. However, because support portions 5c and 5d are located more than 0.25L (0.25 times the maximum length L of the panel 1) away from the central line 12 in the distance perpendicular to the central line 12, it can be considered that the panel 1 is supported on two sides by support portions 5a to 5c and support portions 5d to 5f.

[0058] The maximum length L of the panel 1, i.e., the maximum length of the panel 1 in the direction perpendicular to the central straight line 12, is, for example, 760 mm to 1160 mm, specifically, for example, 760, 800, 850, 900, 950, 1000, 1050, 1100, 1150, or 1160 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0059] The maximum width W of the panel 1, i.e., the maximum length of the panel 1 in the direction parallel to the central straight line 12, is, for example, 430 mm to 830 mm, and specifically may be, for example, 430, 450, 500, 550, 600, 650, 700, 750, 800, or 830 mm, or may be within a range between any two of the values ​​exemplified here. The first and second main directions of the panel 1 are indicated by arrows x and y, respectively, in FIG. 7.

[0060] 3-2. Manufacturing method of panel 1 The manufacturing method of the panel 1 of the third embodiment may be the same as that of the panel 1 of the first embodiment.

[0061] 4. Fourth embodiment 4-1. Structure of Panel 1 The structure of the panel 1 of the fourth embodiment shown in Figure 8 differs from the structure of the panel 1 of the first embodiment in the shape of the panel 1, the number and arrangement of the support parts, the arrangement of the deformation promoting parts, and the presence or absence of openings, but the other features are the same as those of the panel 1 of the first embodiment.

[0062] Panel 1 is supported on the second face material 4 side of panel 1 by support portions 5a to 5n, but support portions 5f to 5i are arranged on the periphery that is located inside a pair of ends of longest peripheral section 10a in the distance perpendicular to center line 12 and that faces longest peripheral section 10a, and support portions 5g and 5h are located within 0.25L (0.25 times the maximum length L of panel 1) from center line 12 in the distance perpendicular to center line 12, so it can be considered that panel 1 is essentially supported on three sides by support portions 5a to 5e, support portions 5f to 5i and support portions 5j to 5n.

[0063] Three-sided support can be said to be preferable in terms of impact resistance compared to two-sided support as in embodiments 1 to 3, for example, but in this embodiment, three-sided support is preferable because the impact resistance of panel 1 is affected by openings 7a and 7b.

[0064] In this embodiment, the deformation promoting portions 6a-6e are arranged on the periphery of the panel 1 as shown in embodiments 1-3, and also arranged within the second panel material 4 at positions on the periphery of the openings 7a and 7b and around the center line 12. The second panel material 4 is subject to tensile deformation due to bending of the panel 1, and this can result in tensile stress concentration around the openings 7a and 7b (particularly at the positions of the deformation promoting portions 6b-6d on the periphery of the openings 7a and 7b, as described above). By providing the deformation promoting portions 6b-6d in such areas, the second panel material 4 is more susceptible to plastic deformation, and buckling deformation due to bending of the panel 1 can be suppressed.

[0065] The maximum length L of the panel 1, i.e., the maximum length of the panel 1 in the direction perpendicular to the central straight line 12, is, for example, 870 mm to 1270 mm, specifically, for example, 870, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, or 1270 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0066] The maximum width W of the panel 1, i.e., the maximum length of the panel 1 in the direction parallel to the central straight line 12, is, for example, 730 mm to 1130 mm, and specifically, for example, 730, 750, 800, 850, 900, 950, 1000, 1050, 1100, or 1130 mm, or may be within a range between any two of the values ​​exemplified here. The first and second main directions of the panel 1 are indicated by arrows x and y, respectively, in FIG. 8.

[0067] 4-2. Manufacturing method of panel 1 The manufacturing method of the panel 1 of the fourth embodiment may be the same as that of the panel 1 of the first embodiment. The openings 7a and 7b may be formed, for example, by punching out the core material 2, the first face material 3, and the second face material 4 before the core material 2 and the first face material 3, and the core material 2 and the second face material 4 are bonded together.

[0068] 5. An example of the mechanism by which the impact resistance of the panel 1 can be improved by plastic deformation of the second surface material 4 In the case of a panel 1 using a second face material 4 that does not have a deformation promoting portion, the energy of the impact caused by a dropped package (e.g., box 9) is absorbed by buckling (bending) of the first face material 3, but in the case of a panel 1 using a second face material 4 that has a deformation promoting portion, the energy is absorbed by plastic tensile deformation of the second face material 4, which suppresses buckling of the first face material 3 and improves the impact resistance of the panel 1. In other words, impact resistance is improved by having the second face material 4 absorb more energy than the first face material 3.

[0069] Although the embodiments have been described above, the technical ideas of the present disclosure can also be adopted in the following aspects.

[0070] The bond between the core material 2 and the first face material 3 and / or the bond between the core material 2 and the second face material 4 may have a region that is not partially bonded.

[0071] 9, the core material 2 may have small recesses 8b that are smaller than the recesses 8a (recesses to which the first surface material 3 and the second surface material 4 can be fixed) of the core material 2 already described. In the small recesses 8b, for example, the core material 2 and the first surface material 3 and / or the core material 2 and the second surface material 4 may not be joined together.

[0072] The core material 2 and the first surface material 3 and / or the core material 2 and the second surface material 4 may be joined by fusion bonding instead of by adhesion with an adhesive.

[0073] If necessary, a skin material may be provided to cover the core material 2, the first face material 3, and the second face material 4. This improves the appearance and prevents the first face material 3 and / or the second face material 4 from peeling off from the core material 2. In one example, the skin material is a nonwoven fabric, and can be adhered to the core material 2, the first face material 3, and the second face material 4 via an adhesive layer. [Example]

[0074] 6. Impact resistance analysis The impact resistance test was modeled using the following method.

[0075] In the panel 1 of the first embodiment, a numerical analysis was performed to model how the impact resistance of the panel 1 changes depending on whether or not the deformation promoting portions 6a and 6b are present. In this analysis, the deformation promoting portions 6a and 6b were modeled as notches.

[0076] Impact resistance was determined by dropping a 6 kg box 9 from a height of 1 m vertically from the upper edge of the panel 1 (upper edge 3a of the first face material 3) and determining whether buckling deformation occurred in the panel 1. Specifically, if buckling deformation occurred in the first face material 3 of the panel 1, the panel was determined to lack impact resistance.

[0077] If the analysis determines that buckling deformation will occur, the actual panel is likely to experience buckling deformation and / or cracks due to impact, making it impossible for the panel to continue functioning as a deck board or the like installed in the trunk of a vehicle (no impact resistance).On the other hand, if the analysis determines that only plastic deformation will occur, the actual panel will be able to continue functioning as a deck board or the like (impact resistance), although deformation will be observed (impact resistance).

[0078] The thickness of the core material 2, the thickness of the first face material 3, and the thickness of the second face material 4 were constant at 20 mm, 0.38 mm, and 0.20 mm, respectively. The length and width of the core material 2, the first face material 3, and the second face material 4 were all 1000 mm and 450 mm, respectively. Furthermore, the length and width of the bottom of the box 9 (the surface that comes into contact with the panel 1 when dropped) were 220 mm and 180 mm, respectively.

[0079] Figure 10A shows the model used in this impact resistance analysis. This analysis was performed using analysis software based on the finite element method (Ansys LS-DYNA, manufactured by Ansys Inc.). As shown in Figure 10B, the mesh of panel 1 (a division for decomposing the model into finite elements) where the short side of the bottom of box 9 comes into contact is set finer than the mesh of other parts of panel 1, which makes it possible to accurately determine stress concentration (and the resulting buckling deformation).

[0080] The analysis was carried out for two cases: one in which there was no notch in the second face material 4, and one in which there was a pair of notches as shown in Figure 10C. Each of the pair of notches was 220 mm long and 10 mm wide.

[0081] The physical properties of each component of Panel 1 were as shown in Table 1 below.

[0082] [Table 1]

[0083] The materials for the first and second face materials 3 and 4 were assumed to be aluminum (AL5052), and the material for the core material 2 was assumed to be expanded polypropylene (EPP). The elastoplastic behavior of the core material 2, the first face material 3, and the second face material 4 was modeled using a polylinear approximation of the stress-strain curves of AL5052 and EPP, primarily using the physical properties in Table 1. In particular, the elastoplastic behavior of the core material 2 was modeled using a material model for foam materials. Furthermore, the box 9 dropped onto the panel 1 was modeled as an elastic body (without plastic behavior) with stiffness several times greater than the components of the panel 1.

[0084] The bond between the core material 2 and the first face material 3, and the bond between the core material 2 and the second face material 4 were modeled as perfect bonds with no sliding or separation occurring at the interface between the core material 2 and each face material.

[0085] Panel 1 is supported by a pair of supports 5a and 5b arranged along its short sides, and supports 5a and 5b are modeled as elastic bodies with stiffness several times greater than that of the panel, similar to box 9. At the interface between panel 1 and supports 5a and 5b, the physical properties of the interface were appropriately set so that slippage and peeling are permitted but excessive penetration is not permitted.

[0086] 6-1.Analysis results 11A and 11B show the analysis results for the case without a notch and the case with a notch, respectively. Specifically, these figures show the time series changes in the energy possessed by each component of panel 1, and indicate how much of the potential energy of box 9 was absorbed by each component of panel 1. In the case without a notch, a break (buckling of first panel 3) occurred, but in the case with a notch, no break occurred.

[0087] Comparing the energy distribution for the case without a cutout (Fig. 11A) and the case with a cutout (Fig. 11B), we can see that the proportion of energy accounted for by the second panel 4 (referred to as "back AL" in the legend of Fig. 11) is larger in the case with a cutout 10 msec after the box 9 hits the panel 1. Furthermore, we can see that the proportion of energy accounted for by the first panel 3 (referred to as "front AL" in the legend of Fig. 11) is smaller in the case with a cutout. These results indicate that the cutout (deformation promoting portion) promotes the plastic tensile deformation of the second panel 4, thereby absorbing energy into the second panel 4 and suppressing energy absorption (and resulting buckling deformation) of the first panel 3. In other words, impact resistance is improved by having the second panel 4 absorb more energy than the first panel 3. [Explanation of symbols]

[0088] 1: Panel 2: Core material 2a: upper edge 2b: lower edge 3: First surface material 3a: upper edge 3b: lower edge 4: Second surface material 4a: Upper edge 4b: Lower edge 5a: Support part 5b: Support part 5c: Support part 5d: Support part 5e: Support part 5f: Support part 5g: Support part 5h: Support part 5i: Support part 5j: Support part 5k: Support part 5l: Support part 5m: Support part 5n: Support part 6a: Deformation promoting section 6b: Deformation promotion section 6c: Deformation promotion section 6d: Deformation promotion section 6e: Deformation promotion section 7a: Opening 8a: Recess 8b: Small recess 9:Box 10a: Peripheral section 10b: Peripheral section 10c: Peripheral section 10d: Peripheral section 11a: Center point 12: Central line 61: Notch 62: Slit F :Force G: Center of gravity x :arrow y : arrow z :arrow

Claims

1. A panel comprising a core material, a first face material, and a second face material, the core material is sandwiched between the first face material and the second face material, the first face material and the second face material are bonded to the core material, The second surface material has one or more deformation promoting portions that promote plastic tensile deformation of the second surface material, The panel is supported by a plurality of support portions on the second panel side.

2. 2. The panel of claim 1, The plurality of support portions are arranged along the periphery of the panel, A panel in which at least a portion of the deformation promoting portion is positioned within a distance from a center line passing through an area of ​​the panel where bending stress is concentrated, in a direction perpendicular to the center line, of 10.0% of the maximum length of the panel in the perpendicular direction.

3. 3. The panel of claim 2, The total length of each of the one or more deformation promoting portions in a direction parallel to the center line w ｔｏｔａｌ The ratio w of the maximum length W of the panel in the parallel direction to ｔｏｔａｌ The panel has a value of / W of 0.011 to 0.

078.

4. 4. The panel of claim 3, The length l of each of the one or more deformation promoting portions in a direction perpendicular to the central straight line ｉ and the maximum length L of the panel in the vertical direction, ｉ The panel has a value of / L of 0.020 to 0.

420.

5. The panel according to any one of claims 1 to 4, The panel includes an opening.

6. 6. The panel of claim 5, A panel, wherein some of the one or more deformation promoting portions are provided along a periphery of the opening.

Images