Patent Application
20130295406
The present invention relates to a sheet material whose stiffness is increased by the formation of a concave-convex part, and to a vehicle panel and a laminated structure that are configured using the same.
With the aim of reducing the weight of, for example, an automobile, the potential replacement of the material of components comprising steel sheets and the like with a lightweight material such as an aluminum alloy sheet is being studied and implemented. In such a case, assuming that the weight is reduced, it is necessary that the required stiffness be ensured.
To date, studies conducted to increase stiffness without increasing the thickness of the sheet material have provided the sheet material with a wave shape, a concave-convex shape, and the like, and the stiffness has been increased by virtue of the shape.
As an example of implementing a convex-concave shape, one of the components, called a heat insulator, of an automobile is formed of a sheet material. As a material therefor, Patent Document 1 proposes the formation of numerous protruding parts by embossing in order to ensure sufficient stiffness without increasing sheet thickness. In addition, sheet materials have also been proposed (refer to Patent Documents 2-7) that increase stiffness not only in a heat insulator but also in various applications by forming a concave-convex part via embossing and the like.
Patent Document 1: Japanese Patent No. 4388558
Patent Document 2: Japanese Patent No. 3332353
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2000-257441
Patent Document 4: Japanese Unexamined Patent Application Publication No. 9-254955
Patent Document 5: Japanese Unexamined Patent Application Publication No. 2000-288643
Patent Document 6: Japanese Unexamined Patent Application Publication No. 2002-307117
Patent Document 7: Japanese Unexamined Patent Application Publication No. 2002-321018
A sheet material wherein corrugations, numerous concave-convex parts, and the like are formed is actually stiffer than a flat sheet in which concave-convex parts are not formed. Nevertheless, the stiffness of a sheet material provided with a corrugated shape has directionality, namely, there are cases wherein even though the stiffness increases in one direction, the desired stiffness increase effect is not obtained in another direction. In addition, in the sheet material provided with the concave-convex part described in Patent Document 1, Patent Document 2, and the like, even though stiffness anisotropy is reduced, the stiffness increase effect thereof is approximately only two times and the weight reduction effect thereof is approximately only 20% of a flat sheet wherein the concave-convex part is not formed, and these effects cannot necessarily satisfy the demand. Consequently, it cannot be said that the optimal concave-convex part shape that both increases stiffness and reduces weight has yet been elucidated, and there is always a demand for further increases in the stiffness increase effect and the weight reduction effect. In addition, apart from the need to reduce weight, there is also anticipation for a material cost reduction effect; when it comes to a sheet material (i.e., a sheet-shaped material), there is demand for increased stiffness and decreased weight—regardless of the material.
In addition, there is demand for a high degree of stiffness over and above that of the conventional art even for, for example, laminated structures that use a sheet material having a concave-convex part that features a high stiffness increase effect, vehicle panels that incorporate a sheet material having a concave-convex part that features a high stiffness increase effect, and the like.
The present invention was conceived considering this background, and it is an object of the present invention to provide a sheet material that has a concave-convex part pattern and whose stiffness is higher than that of the conventional art, and to provide a vehicle panel and a laminated structure that uses the same.
A first aspect of the invention is a sheet material whose stiffness is increased by the formation of a concave-convex part, wherein
a first reference plane and a second reference plane, which are two virtual planes that are spaced apart from and parallel to one another, are used as a reference;
numerous substantially H shaped first reference areas, each comprising two parallel longitudinal bar parts and a latitudinal bar part that connects them together at their center portions, are arrayed with the same orientation in the second reference plane;
a plurality of first reference area rows, wherein a plurality of the first reference areas is arrayed in a row in the X directions in each of the first reference area rows, is formed wherein the longitudinal directions of the longitudinal bar parts are the Y directions and the directions orthogonal thereto are the X directions;
any arbitrary two rows of the first reference area rows adjacent to one another in the Y directions are disposed with a positional relationship such that a state obtains wherein a total of two of the longitudinal bar parts of two of the first reference areas—one longitudinal bar part per first reference area—adjacent to one another in the X directions and belonging to one of the first reference area rows penetrates the space between a pair of the longitudinal bar parts of one of the first reference areas belonging to the other first reference area row; and
the concave-convex part is provided with first areas, each of which comprises a first top surface that is a projection of its first reference area into the first reference plane at either unity or reduced magnification such that the first top surface protrudes from the first reference area in the second reference plane toward the first reference plane, and first side surfaces that connect the contour of that first top surface and the contour of the corresponding first reference area.
Another aspect of the invention is a laminated structure wherein multiple sheet materials are laminated, wherein at least one of the sheet materials is a sheet material that has the concave-convex part.
Yet another aspect of the present invention is a vehicle panel that has an outer panel and an inner panel, which is joined to a rear surface of the outer panel, wherein one or both of the inner panel and the outer panel comprises a sheet material that has a concave-convex part.
In the sheet material having the concave-convex part, the concave-convex part is provided with the first areas, each of which protrudes from the first reference areas defined in the second reference plane toward the first reference plane. Furthermore, each of the first areas comprises the first top surface and the first side surfaces, which connect the contour of that first top surface and the contour of the corresponding first reference area.
Because it has such a structure, the sheet material has superior bending stiffness as well as superior energy absorption characteristics.
The following considers reasons why the stiffness is increased. Namely, each of the first areas comprises: one of the first top surfaces, which is disposed in the first reference plane disposed at a position that is spaced apart from the neutral plane of the sheet material, and the first side surfaces that intersect in the thickness directions of the sheet material. Consequently, a large amount of the sheet material can be disposed at a position that is spaced apart from the neutral plane of the sheet material. Accordingly, the large amount of material can be used effectively, and thereby the stiffness increase effect can be increased greatly.
In particular, the first reference areas, which are the basic shapes of the first areas, are each substantially H shaped, and the positional relationship of adjacency in the X directions is established as mentioned above, wherein the longitudinal bar parts of two of the first reference areas penetrate, in the Y directions, the space between the pair of longitudinal bar parts of one of the first reference areas. Thereby, the second moment of area can be improved in any cross section taken along any direction, thereby making it possible to obtain a concave-convex shape with a superior bending stiffness increase effect and low stiffness anisotropy. In addition, attendant with the increase in the stiffness, it is also possible to obtain the effect of improving damping characteristics; in addition, the concave-convex shape makes it possible to obtain the effect of suppressing sound reverberations.
In the abovementioned laminated structure, a laminated structure of extremely high stiffness can be easily obtained by using, in at least part of the abovementioned laminated structure, the sheet material having the concave-convex part that exhibits the stiffness increase effect as mentioned above. In addition, it is possible to obtain the damping improvement effect attendant with the increase in stiffness, and to obtain the sound absorption improvement effect by virtue of containing air layers.
In the vehicle panel, the sheet material that has the concave-convex part having the stiffness increase effect as mentioned above is used in the outer panel or the inner panel, or both, and thereby it is possible to easily obtain a vehicle panel whose stiffness is extremely high. In addition, it is possible to obtain the damping improvement effect attendant with the stiffness increase, and to obtain the sound absorption improvement effect by virtue of containing air layers.
In the present invention, the expression “H shape” refers to shapes that can generally be recognized as H shapes; for example, shapes that would naturally be allowed include: shapes wherein the sides are somewhat curved; so-called fillets wherein a round and the like needed for forming a molded shape is created in a corner part, a surface, and the like; and shapes provided with a so-called curvature.
In addition, in the present invention, the expression “parallel” is not limited to the narrow concept of geometry and may be anything that can generally be recognized as being parallel.
In addition, the first top surfaces in the sheet material that has the concave-convex part can also be configured by surfaces in the first reference plane or by regions that protrude from the first reference plane in the reverse direction to the direction in which the second reference plane is disposed. Examples of the shape of the protruding regions include a dome, a ridgeline, and a cone, but the shape of the protruding regions is not limited thereto.
In addition, in any arbitrary two rows of the first reference area rows that are adjacent in the Y directions, the amount by which a total of two of the longitudinal bar parts of two of the first reference areas—one longitudinal bar part per first reference area—that are adjacent in the X directions and belong to one of the first reference area rows penetrates the space between a pair of the longitudinal bar parts of one of the first reference areas belonging to the other first reference area row is preferably in the range of 0.2-1.0 E, in contrast to a protrusion length E, which is the amount by which the longitudinal bar parts protrude from the latitudinal bar parts in the Y directions. In this case, it is possible to obtain formability and a sufficient stiffness increase effect. If the penetration is less than 0.2 E, then it might not be possible to obtain a sufficient stiffness increase effect. In addition, if the penetration exceeds E, then the prescribed shape cannot be obtained.
In addition, it is also possible to make the penetrations different for each of the two adjacent first reference areas. In this case, too, it is possible to obtain a sheet material that exhibits both superior bending stiffness and excellent energy absorption characteristics.
In addition, in the second reference plane, the first reference areas are preferably disposed regularly. If the first reference areas are disposed irregularly, then the shape of the concave-convex part will also become irregular, and thereby local changes in stiffness may arise, resulting in unstable stiffness and anisotropy thereof.
In addition, the first reference areas may be disposed without any gaps over the entire surface of the second reference plane; it is also possible to provide gaps between the first reference areas and to have those gap portions coexist, as second reference areas, with the first reference areas as follows. Namely, it is also possible for the first reference areas and the second reference areas, which are those areas that exclude the first reference areas, to coexist in the second reference plane, and to provide second areas, each of which comprises a second top surface that is a projection of its second reference area into the first reference plane at either unity or reduced magnification such that the second top surface protrudes from the second reference area toward the first reference plane and second side surfaces that connect the contour of that second top surface and the contour of the corresponding second reference area, or plane areas, each of which comprises the second reference area in the second reference plane.
If the second areas are provided, then the concave-convex part comprises the first areas and the second areas, which are formed from the second reference plane to the first reference plane. In this case, too, it is possible to obtain a sheet material that exhibits both superior bending stiffness and excellent energy absorption characteristics. In addition, if the plane areas are provided, then the concave-convex part comprises the first areas and the plane areas. In this case, the first top surfaces can be formed in the first reference plane, which is spaced apart from the neutral plane of the sheet material, and the plane areas can be formed in the second reference plane. Accordingly, numerous members can be disposed on both sides of the neutral plane, which makes it possible to further enhance the bending stiffness increase effect of the sheet material having the concave-convex part.
In addition, if the second areas are provided, then each of the second top surfaces can also comprise a surface in the first reference plane or comprise a region that protrudes in a direction opposite to the direction in which the second reference plane is disposed with respect to the first reference plane. In addition, each of the plane areas can also comprise a surface in the second reference plane or comprise a region that protrudes in a direction opposite to the direction in which the first reference plane is disposed with respect to the second reference plane. Examples of the shape of the protruding regions include a dome, a ridgeline, and a cone, but the shape of the protruding regions is not limited thereto.
In addition, the width dimension in the X directions of each of the longitudinal bar parts is designated as a reference dimension A (mm), and a dimension B (mm), which is the width of each of the longitudinal bar parts in the Y directions, preferably is related to the reference dimension A (mm) by 3A≦B≦13A; furthermore, a dimension C (mm), which is the width of each of the latitudinal bar parts in the X directions, preferably is related to the reference dimension A (mm) by 2A≦C≦10A; furthermore, a dimension D (mm), which is the width of each of the latitudinal bar parts in the Y directions, preferably is related to the reference dimension A (mm) by A≦D≦3A; furthermore, the dimension B (mm) and the dimension D (mm) preferably have the relationship B≧D+2A. In this case, it is possible to form a superior concave-convex part shape wherein the bending stiffness increase effect is high and the bending stiffness anisotropy is low.
If the dimension B (mm) is less than 3A or exceeds 13A, then the bending stiffness anisotropy increases, which is not preferable.
In addition, if the dimension C (mm) is less than 2A, then the first reference areas cannot be disposed in the sheet material that has the concave-convex part. In addition, if the dimension C (mm) exceeds 10A, then the bending stiffness anisotropy increases, which is not preferable.
In addition, if the dimension D (mm) is less than A or exceeds 3A, then the bending stiffness anisotropy increases, which is not preferable.
In addition, if the relationship between the dimension B (mm) and the dimension D (mm) becomes B<D+2A, then the shape of each of the first reference areas cannot be made a substantially H shape, and the bending stiffness anisotropy increases, neither of which is preferable.
In addition, an inclination angle θ1(°) of the first side surface with respect to the second reference plane is preferably in the range of 10°-90°, and an inclination angle θ2(°) of the second side surface with respect to the second reference plane is preferably in the range of 10°-90°. If the inclination angle θ1(°) of the first side surface and the inclination angle θ2(°) of the second side surface are in the range of 10°-90°, then a concave-convex part shape that has a superior stiffness increase factor can be obtained while ensuring formability.
If the inclination angle θ1(°) of the first side surface and the inclination angle θ2(°) of the second side surface are less than 10°, then it becomes difficult to increase the height with which the first areas and the second areas protrude, which decreases the stiffness increase factor. In addition, if the inclination angle θ1(°) of the first side surface and the inclination angle θ2(°) of the second side surface exceed 90°, then forming the concave-convex part will be problematic, and such an area will not be needed.
Furthermore, in a case wherein a metal sheet is press formed, because of problems with formability, the upper limit value of the inclination angle θ1(°) of the first side surface and the upper limit value of the inclination angle θ2(°) of the second side surface are more preferably less than or equal to 70°. Accordingly, the range is more preferably 10°-70°.
In addition, the first side surface and the second side surface comprise a plurality of surfaces, but it is not necessary for all of those surfaces to have the same inclination angle; for example, the inclination angle may vary with the region. However, every surface is preferably within the abovementioned preferable inclination angle range.
In addition, at least part of the first reference plane and at least part of the second reference plane are preferably parallel curved surfaces.
In this case, the superior sheet material that has the concave-convex part can be deformed into various shapes, and the range of application can be expanded.
In addition, in a sheet material that has the concave-convex part, the sheet material is preferably one wherein the concave-convex part is formed by press forming a metal sheet. The concave-convex part can be easily formed by plastic working a metal sheet such as by press forming, for example, embossing, or by roll forming. Consequently, the superior concave-convex part shape can be adapted to a metal sheet comparatively easily. Various materials that can be plastically worked, such as aluminum alloy, steel, and copper alloy, can be used as the material of the metal sheet.
Furthermore, in addition to plastic working such as rolling, it is also possible to use casting, cutting, and the like as the forming method.
In addition, as long as it has the concave-convex part, the sheet material is also effective with materials other than metal; for example, the sheet material can also be a resin sheet and the like. In the case of a resin material and the like, the concave-convex part can be formed by, for example, injection molding or hot pressing. Compared with metal material, resin material tends not to be constrained in its formation and has a greater number of degrees of freedom in its design.
In addition, a sheet thickness t (mm) prior to the formation of the metal sheet is preferably 0.03-6.0 mm. When the sheet thickness of the metal sheet is less than 0.03 mm or exceeds 6.0 mm, there is little need to increase its stiffness in application.
In addition, a ratio A/t of the reference dimension A (mm) to the sheet thickness t (mm) is preferably 10-2000.
If the ratio A/t is less than 10, then there is a risk that forming will become difficult; moreover, if the ratio A/t exceeds 2000, then there is a risk that problems will arise, such as it being no longer possible to sufficiently form the concave-convex part shape, and that stiffness will decrease.
In addition, a ratio H/t of a distance H (mm) between the first reference plane and the second reference plan to the sheet thickness t (mm), and the maximum inclination angle θ1(°) formed between the first side surface and the second reference plane preferably have the relationship 1≦(H/t)≦−3θ1+272; and the ratio H/t and the maximum inclination angle θ2(°) formed between the second side surface and the second reference plane preferably have the relationship 1≦(H/t)≦−3θ2+272.
If the ratio H/t is less than 1, then there is a risk that a problem will arise wherein the stiffness increase effect produced by the formation of the first areas will not be sufficient. Moreover, if the ratio H/t exceeds −3θ1+272, then there is a risk that a problem will arise wherein forming will become difficult. Likewise, if the ratio H/t is less than 1, then there is a risk that a problem will arise wherein the stiffness increase effect produced by the formation of the second areas will not be sufficient. Moreover, if the ratio H/t exceeds −3θ2+272, then there is a risk that a problem will arise wherein forming will become difficult.
In addition, in the abovementioned laminated structure, it is possible to configure a laminated body with a three-layer structure wherein the sheet material that has the concave-convex part is used as one core material, and one flat face sheet is provided and disposed on each side thereof. In addition, it is also possible to configure a structure that repeats such a basic structure, namely, a multilayer structure wherein a plurality of the sheet materials, each sheet material having the concave-convex part, is stacked, with a flat face sheet inserted after every sheet material.
In addition, it is also possible to adopt a structure wherein the plurality of sheet materials having the concave-convex parts are directly stacked and used as the core material, and the flat face sheets are joined to a surface on one side thereof or to surfaces on both sides thereof.
In addition, it is also possible to configure a laminated structure in the state wherein the plurality of the sheet materials having the concave-convex parts is just directly stacked.
The number of the sheet materials stacked can be modified in accordance with the application and the required characteristics.
In addition, the abovementioned vehicle panel is not limited to the hood of an automobile and can also be adapted to: a panel, such as a door, a roof, a floor, and a trunk lid; a reinforcing member; and an energy absorbing member, such as a bumper, a crush box, a door beam, and the like. In addition, a steel sheet, an aluminum alloy sheet, or the like can also be used as the outer panel and the inner panel.
If the outer panel comprises an aluminum alloy sheet, then, for example, a 6000 series alloy is ideal because it is relatively low cost. In addition, if the inner panel comprises an aluminum alloy sheet, then, for example, a 5000 series alloy sheet is ideal because it has relatively good formability.
An embodiment of a sheet material 1 that has a concave-convex part 20 will now be explained, referencing
The sheet material 1 that has the concave-convex part 20 of the present embodiment is the sheet material 1 whose stiffness has been increased by the formation of the concave-convex part 20, as shown in
The concave-convex part 20 is configured as follows.
As shown in
In addition, any arbitrary two rows of the first reference area rows L1, L2 adjacent to one another in the Y directions are disposed with a positional relationship such that a state obtains wherein a total of two of the longitudinal bar parts 214 of two of the first reference areas 213—one longitudinal bar part 214 per first reference area 213—adjacent to one another in the X directions and belonging to one of the first reference area rows penetrates the space between a pair of the longitudinal bar parts 214 of one of the first reference areas 213 belonging to the other first reference area row. As shown in
As shown in
In addition, as shown in
As shown in
In addition, as shown in
In addition, as shown in
In addition, in the present embodiment, the sheet material 1 that has the concave-convex part 20 is a 1000 series aluminum sheet whose sheet thickness t=0.3 mm prior to formation of the sheet. The concave-convex part 20 is press formed using a pair of molds. Furthermore, it is also possible to use, as the forming method, some other plastic working method such as roll forming that forms by using a pair of forming rolls, the surfaces of which are profiled with the desired concave-convex shape.
In addition, the ratio A/t of the reference dimension A (mm) to the sheet thickness t (mm) of the aluminum sheet is 26.67, and is within a range of 10-2000.
In addition, the ratio H/t of the distance H (mm), which is the distance between the first reference plane K1 and the second reference plane K2, to the sheet thickness t (mm) is 5. In addition, the inclination angle θ1 formed between each of the first side surfaces 212 and the second reference plane K2 is 30°, and −3θ1+272=182. Accordingly, the relationship 1≦H/t≦182 is satisfied.
Next, the operation and effects of the sheet material 1 that has the concave-convex part 20 according to the present embodiment will be explained.
As mentioned above, the concave-convex part 20 is provided with the first areas 21, each of which protrudes from the first reference areas 213 defined in the second reference plane K2 toward the first reference plane K1. Furthermore, each of the first areas 21 comprises one of the first top surfaces 211 and the first side surfaces 212, which connect the contour of that first top surface 211 and the contour of the corresponding first reference areas 213. In addition, the plane areas 23, which comprise the second reference areas 223, are provided in the second reference plane K2, wherein the second reference areas 223 are those areas in the second reference plane K2 excluding the first reference areas 213.
Because it has such a structure, the sheet material 1 has superior bending stiffness as well as superior energy absorption characteristics.
The following considers reasons why the stiffness is increased. Namely, as shown in
In particular, the first reference areas 213, which are the basic shapes of the first areas 21, are each substantially H shaped, and the positional relationship of adjacency in the X directions is established as mentioned above, wherein the longitudinal bar parts 214 of two of the first reference areas 213 penetrate, in the Y directions, the space between the pair of longitudinal bar parts 214 of one of the first reference areas 213. Thereby, the second moment of area can be improved in any cross section taken along any direction, thereby making it possible to obtain a concave-convex shape with a superior bending stiffness increase effect and low stiffness anisotropy. In addition, attendant with the increase in the stiffness, it is also possible to obtain the effect of improving damping characteristics; in addition, the irregular shape makes it possible to obtain the effect of suppressing sound reverberations. In addition, attendant with the increase in the stiffness, it is also possible to obtain the effect of improving damping characteristics; in addition, the irregular shape makes it possible to obtain the effect of suppressing sound reverberations.
(FEM Analysis)
To quantitatively determine the stiffness increase effect of the sheet material 1 of the present embodiment, a bending stiffness evaluation of a cantilevered beam was performed by FEM analysis.
In the FEM analysis, the bending stiffness evaluation was performed in three directions, namely, 0°, 45°, and 90°, by changing the forming direction of the concave-convex part 20 in a test piece.
The test piece used in the FEM analysis has a rectangular shape measuring 120×120 mm, and the concave-convex part 20 is formed over the entire surface thereof. Furthermore, taking the increase in the surface area into consideration, the sheet thickness t was 0.284 mm.
In an end part of the test piece, one end was designated as a fixed end, and the end part disposed opposing that fixed end was designated as a free end. A load of 1 N was applied to the center part of the side formed by the free end, and the amount of deflection of the sheet material 1 was derived by performing the FEM analysis.
The evaluation was performed by comparing the amount of deflection obtained by conducting the same FEM analysis on the flat sheet shaped original sheet whereon the concave-convex part 20 is not formed.
<0° Direction>
As shown in
The sheet material 1 that has the concave-convex part 20 of the first embodiment was compared, in the 0° direction discussed above, with the flat sheet shaped original sheet, and it was obvious that the bending stiffness increased by 9.16 times.
<45° Direction>
As shown in
The sheet material 1 that has the concave-convex part 20 of the first embodiment was compared, in the 45° direction discussed above, with the flat sheet shaped original sheet, and it was obvious that the bending stiffness increased by 6.83 times.
<90° Direction>
As shown in
The sheet material 1 that has the concave-convex part 20 of the first embodiment was compared, in the 90° direction discussed above, with the flat sheet shaped original sheet, and it was obvious that the bending stiffness increased by 8.03 times.
Based on the results of the FEM analysis, with respect to the sheet material 1 that has the concave-convex part 20 described in the present embodiment, in the 0° direction, which is the direction in which the bending stiffness increase effect is the highest, a stiffness multiplier G is expected to be 9.16 times that of a flat sheet, and a weight reduction factor W (%) is expected to be approximately 52% of a flat sheet.
In addition, with respect to the sheet material 1 that has the concave-convex part 20 described in the present embodiment, in the 45° direction, which is the direction in which the bending stiffness increase effect is the lowest, the stiffness multiplier G is expected to be 6.83 times that of a flat sheet, and the weight reduction factor W (%) is expected to be at least approximately 47% of a flat sheet.
Furthermore, the weight reduction factor W (%) is derived using the stiffness multiplier G based on the formula W=(1−13√{square root over (G)})×100.
In addition, in the present embodiment, the shape of the concave-convex part 20 in the 135° direction is the same as in the 45° direction, and the shape of the concave-convex part 20 in the 180° direction is the same as in the 0° direction. Accordingly, the result of the FEM analysis is the same for both the 135° direction and the 45° direction, and is likewise the same for the 180° direction and the 0° direction.
The sheet material 1 having the concave-convex part 20 according to the present embodiment will now be explained, referencing
As shown in
As shown in
As shown in
In addition, as shown in
(FEM Analysis)
To quantitatively determine the stiffness increase effect of the sheet material 1 of the present embodiment, a bending stiffness evaluation of a cantilevered beam was performed by FEM analysis.
In the FEM analysis, the evaluation was performed in three directions, namely, 0°, 45°, and 90°, by changing the forming direction of the concave-convex part 20 in a test piece.
The test piece used in the FEM analysis has a rectangular shape measuring 120×120 mm, and the concave-convex part 20 is formed over the entire surface thereof. Furthermore, taking the increase in the surface area into consideration, the sheet thickness t was 0.279 mm.
In an end part of the test piece, one end was designated as a fixed end, and the end part disposed opposing that fixed end was designated as a free end. A load of 1 N was applied to the center part of the side formed by the free end, and the amount of deflection of the sheet material 1 was derived by performing the FEM analysis.
The evaluation was performed by comparing the amount of deflection obtained by conducting the same FEM analysis on the flat sheet shaped original sheet whereon the concave-convex part 20 is not formed.
<0° Direction>
As shown in
The sheet material 1 that has the concave-convex part 20 of the present embodiment was compared, in the 0° direction discussed above, with the flat sheet shaped original sheet, and it was obvious that the bending stiffness increased by 10.86 times.
<45° Direction>
As shown in
The sheet material 1 that has the concave-convex part 20 of the present embodiment was compared, in the 45° direction discussed above, with the flat sheet shaped original sheet, and it was obvious that the bending stiffness increased by 5.48 times.
<90° Direction>
As shown in
The sheet material 1 that has the concave-convex part 20 of the present embodiment was compared, in the 90° direction discussed above, with the flat sheet shaped original sheet, and it was obvious that the bending stiffness increased by 4.31 times.
Based on the result of the bending stiffness evaluation of a cantilevered beam performed by FEM analysis, it was obvious that the sheet material 1 having the concave-convex part 20 described in the present embodiment has a particularly superior stiffness increase effect in the 0° direction. In the 0° direction, the combined multiplier G is expected to be 10.86 times that of a flat sheet, and the weight reduction factor W (%) is expected to be approximately 55% of a flat sheet.
In addition, with respect to the sheet material 1 that has the concave-convex part 20 described in the present embodiment, in the 90° direction, which is the direction in which the bending stiffness increase effect is the lowest, the stiffness multiplier G is expected to be 4.31 times that of a flat sheet, and the weight reduction factor W (%) is expected to be at least approximately 39% of a flat sheet.
Furthermore, the weight reduction factor W (%) is derived using the stiffness multiplier G based on the formula W=(1−13√{square root over (G)})×100.
In addition, in the present embodiment, the shape of the concave-convex part 20 in the 135° direction is the same as in the 45° direction, and the shape of the concave-convex part 20 in the 180° direction is the same as in the 0° direction. Accordingly, the result of the FEM analysis is the same for both the 135° direction and the 45° direction, and is likewise the same for the 180° direction and the 0° direction.
The sheet material 1 having the concave-convex part 20 according to the present embodiment will now be explained, referencing
In the present embodiment, as in the second embodiment, the first reference areas 213 are disposed in the second reference plane K2, as shown in
(FEM Analysis)
To quantitatively determine the stiffness increase effect of the sheet material 1 of the present embodiment, a bending stiffness evaluation of a cantilevered beam was performed by FEM analysis.
In the FEM analysis, the evaluation was performed in three directions, namely, 0°, 45°, and 90°, by changing the forming direction of the concave-convex part 20 in a test piece.
The test piece used in the FEM analysis has a rectangular shape measuring 120×120 mm, and the concave-convex part 20 is formed over the entire surface thereof. Furthermore, taking the increase in the surface area into consideration, the sheet thickness t was 0.272 mm.
In an end part of the test piece, one end was designated as a fixed end, and the end part disposed opposing that fixed end was designated as a free end. A load of 1 N was applied to the center part of the side formed by the free end, and the amount of deflection of the sheet material 1 was derived by performing the FEM analysis.
The evaluation was performed by comparing the amount of deflection obtained by conducting the same FEM analysis on the flat sheet shaped original sheet whereon the concave-convex part 20 is not formed.
<0° Direction>
As shown in
The sheet material 1 that has the concave-convex part 20 of the present embodiment was compared, in the 0° direction discussed above, with the flat sheet shaped original sheet, and it was obvious that the bending stiffness increased by 8.11 times.
<45° Direction>
As shown in
The sheet material 1 that has the concave-convex part 20 of the present embodiment was compared, in the 45° direction discussed above, with the flat sheet shaped original sheet, and it was obvious that the bending stiffness increased by 3.92 times.
<90° Direction>
As shown in
The sheet material 1 that has the concave-convex part 20 of the present embodiment was compared, in the 90° direction discussed above, with the flat sheet shaped original sheet, and it was obvious that the bending stiffness increased by 3.79 times.
Based on the result of the bending stiffness evaluation of a cantilevered beam performed by the abovementioned FEM analysis, it was obvious that the stiffness increase effect of the sheet material 1 having the concave-convex part 20 described in the present embodiment was particularly superior in the 0° direction. In the 0° direction, the combined multiplier G is expected to be 8.11 times that of a flat sheet, and the weight reduction factor W (%) is expected to be approximately 50% of a flat sheet.
In addition, in the 90° direction, which is the direction in which the bending stiffness increase effect is the lowest, the stiffness multiplier G is expected to be 3.79 times that of a flat sheet, and the weight reduction factor W (%) is expected to be at least approximately 36% of a flat sheet.
Furthermore, the weight reduction factor W (%) is derived using the stiffness multiplier G based on the formula W=(1−13√{square root over (G)})×100.
In addition, in the present embodiment, the shape of the concave-convex part 20 in the 135° direction is the same as in the 45° direction, and the shape of the concave-convex part 20 in the 180° direction is the same as in the 0° direction. Accordingly, the result of the FEM analysis is the same for both the 135° direction and the 45° direction, and is likewise the same for the 180° direction and the 0° direction.
The present embodiment is an example wherein, in contrast to the first through third embodiments, the shape and arrangement of the first reference areas 213 in the second reference plane K2 has been changed. In the present embodiment, the shape of the sheet material 1 having the concave-convex part 20 is described by the arrangement of the first reference areas 213 alone or of the first reference areas 213 and the second reference areas 223 in the second reference plane K2. In either case, the sheet material 1 having the concave-convex part 20 is formed based on the second reference plane K2 shown in the figure.
In
In the second reference plane K2 shown in
In the second reference plane K2 shown in
In addition, in the second reference plane K2 shown in
In the sheet material 1 having the concave-convex part 20 in the second reference plane K2 described in the present embodiment, too, it is possible to obtain the sheet material 1 with low bending stiffness anisotropy and a high bending stiffness increase effect.
The present embodiment, as shown in
As described in the present embodiment, the sheet material 1 that has the concave-convex part 20 provided with superior characteristics can be deformed into a variety of shapes, thereby expanding its range of application.
In addition, by using a cylindrical structure like a beverage can or a rocket, it is possible to increase the stiffness of the cylindrical member 11 that has the concave-convex part 20 described in the present embodiment without increasing the sheet thickness of the material. In addition, the cylindrical member 11 of the present embodiment has superior energy absorption characteristics. Consequently, using such in a vehicle body of an automobile and the like imparts high stiffness and superior energy absorption characteristics.
The present embodiment, as shown in
Namely, the laminated structure 5 joins face sheets 42, 43 to the surfaces on both sides of the core material, which consists of one sheet material 1 that has the concave-convex part 20.
The face sheets 42, 43 are aluminum alloy sheets that are made of 3000 series material and whose sheet thickness is 1.0 mm.
In the laminated structure 5 of the present embodiment, the sheet material 1 that has the concave-convex part 20, which has superior stiffness as discussed above, is used as the core material, and the face sheets 42, 43 are joined, by bonding, brazing, and the like, to the first top surfaces 211 of the first areas 21 and to the plane areas 23; thereby, the laminated structure 5 obtains a remarkably higher stiffness than that of the sheet material 1 that has the concave-convex part 20 as a standalone. Moreover, because the sheet material 1 and the face sheets 42, 43 are aluminum alloy sheets, the weight is also reduced.
In addition, it is possible to obtain the effect of improving the damping characteristics attendant with the increase in stiffness, and to obtain the effect of improving the sound absorbing characteristics by virtue of containing air layers. In addition, as is well known, the sound absorbing characteristics can be further improved via the formation of a through hole in either of the face sheets 42, 43 so as to form a Helmholtz sound-absorbing structure.
Furthermore, it is also possible to use, as the face sheets 42, 43, a sheet made of resin or a metal other than an aluminum alloy, for example, a steel sheet or a titanium sheet.
The present embodiment, as shown in
In the vehicle panel 6 of the present embodiment, the sheet material 1 that has the concave-convex part 20 and that constitutes the inner panel obtains an excellent stiffness increase effect, as mentioned above, and therefore has the excellent characteristic of absorbing the energy of a primary impact as well as the energy of a secondary impact in the event the vehicle collides with a pedestrian. In addition, it is possible to obtain the effect of improving the damping characteristics attendant with the increase in stiffness, and to obtain the effect of improving the sound absorbing characteristics by virtue of containing an air layer.
Furthermore, in the present embodiment, the sheet material 1 that has the concave-convex part 20 is used as the inner panel, but the sheet material 1 can also be used as the inner panel or the outer panel 61, or both.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-281277 | Dec 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/061477 | 5/19/2011 | WO | 00 | 6/12/2013 |
