Vibration damping member, method for manufacturing vibration damping member, and system for manufacturing vibration damping member

Abstract

To provide a vibration suppressing member having a band gap and improved in applicability as a structural member.SOLUTION: In the vibration suppressing member 1, the first metal cell 11 and the second metal cell 12 are alternately arranged by connecting the plurality of unit cells 10 in the first direction X, and the outermost outer surface 15 of the plurality of unit cells 10 in the thickness direction Z is smooth. In each of the unit cells 10, the rigidity of the first metal cell 11 is different from the rigidity of the second metal cell 12, or the mass per unit length of the first metal cell 11 in the first direction X is different from the mass per unit length of the second metal cell 12 in the first direction X, or the rigidity of the first metal cell 11 is different from the rigidity of the second metal cell 12, and the mass per unit length of the first metal cell 11 in the first direction X is different from the mass per unit length of the second metal cell 12 in the first direction X.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a vibration damping member, a method for manufacturing a vibration damping member, and a system for manufacturing a vibration damping member. [Background technology]

[0002] Automobiles, railway vehicles, industrial machinery, home appliances, and other products require lightweight, high-speed, eco-friendly, and low-cost features. However, these requirements often result in vibration and noise problems, making achieving both a significant challenge. To address these issues, vibration-damping devices such as dynamic vibration absorbers and vibration-damping dampers, as well as vibration-damping materials such as vibration-damping rubber, are used. However, installing vibration-damping devices in products that require vibration suppression requires space, limiting their application. Furthermore, highly vibration-damping materials such as rubber have an extremely low elastic modulus, making them difficult to apply to products that require rigidity.

[0003] Research and development is being conducted into vibration suppression materials that utilize bandgaps as a new vibration suppression mechanism that can solve the above problems. Bandgaps refer to a specific frequency range in which vibration propagation is suddenly suppressed in a structure in which materials and structures with properties different from the bandgap are repeated. Vibration suppression materials with such bandgaps can realize a vibration suppression method that differs from applying vibration-damping devices or materials to structures.

[0004] Patent Document 1 discloses that a vehicle power mount unit structure having a periodic structure in which elastic plates made of rubber and metal plates made of steel, aluminum, or the like are alternately laminated is provided between a power unit bracket and a vehicle body bracket. It also discloses that by periodically providing differences in stiffness and mass from the power unit bracket to the vehicle body bracket, a band gap is generated in which the propagation of vibration waves in a frequency band corresponding to the difference in stiffness and mass is weakened, thereby suppressing the propagation of vibration to the vehicle body. Patent Document 1 also discloses that a band gap-generating frequency band appears for a periodic structure plate in which the plate thickness is periodically changed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-070334 Summary of the Invention [Problem to be solved by the invention]

[0006] The power mount unit structure of Patent Document 1 uses an elastic plate made of rubber, which has the problem of insufficient rigidity. Also, the power mount unit structure of Patent Document 1 has an elastic plate and a metal plate laminated in the thickness direction, which suppresses vibrations transmitted in the thickness direction, in other words, in the direction of repetition between the elastic plate and the metal plate, but has the problem of not suppressing vibrations transmitted in a direction perpendicular to the direction of repetition between the elastic plate and the metal plate.

[0007] Furthermore, the periodic structure plate of Patent Document 1 has a concave-convex shape on its surface, which makes it difficult to achieve a desirable design. The periodic structure plate of Patent Document 1 also has maintenance issues, such as the surface's concave-convex shape easily becoming dirty and making it difficult to clean. Furthermore, the periodic structure plate of Patent Document 1 has recessed spaces on the side with the concave-convex shape, which limits the installation location and makes it difficult to place the plate flat, which makes it difficult to install. In other words, the periodic structure plate of Patent Document 1 has issues in terms of its applicability as a structural member, such as design, maintenance, and installation.

[0008] The present disclosure has been made in view of the problems inherent in the conventional techniques, and an object of the present disclosure is to provide a vibration damping member having a band gap and having improved applicability as a structural member, a method for manufacturing a vibration damping member, and a system for manufacturing a vibration damping member. [Means for solving the problem]

[0009] A vibration suppression member according to a first aspect of the present disclosure includes a plurality of unit cells, each of which includes a first metal cell and a second metal cell, and each of which is connected in a first direction perpendicular to the thickness direction. The plurality of unit cells are connected in the first direction, so that the first metal cells and the second metal cells are arranged alternately. The plurality of unit cells have smooth outer surfaces in the thickness direction. In each of the unit cells, the stiffness of the first metal cell is different from the stiffness of the second metal cell, or the mass per unit length in the first direction of the first metal cell is different from the mass per unit length in the first direction of the second metal cell, or the stiffness of the first metal cell is different from the stiffness of the second metal cell, and the mass per unit length in the first direction of the first metal cell is different from the mass per unit length in the first direction of the second metal cell.

[0010] A second aspect of the present disclosure provides a method for manufacturing a vibration damping member. The vibration damping member includes a plurality of unit cells, each of which includes a first metal cell and a second metal cell, and the first metal cell and the second metal cell are connected in a first direction perpendicular to the thickness direction. The unit cells are connected in the first direction, so that the first metal cells and the second metal cells are arranged alternately. The unit cells have smooth outer surfaces in the thickness direction. In each of the unit cells, the stiffness of the first metal cell is different from that of the second metal cell, or the mass per unit length in the first direction of the first metal cell is different from that of the second metal cell, or the stiffness of the first metal cell is different from that of the second metal cell, and the mass per unit length in the first direction of the first metal cell is different from that of the second metal cell. The method for manufacturing a vibration damping member includes a dispersion curve acquisition step of acquiring a dispersion curve representing the relationship between frequency and wave number of the vibration damping member. The method for manufacturing a vibration suppression member includes a step of identifying parameters including at least one selected from the group consisting of Young's modulus, density, length, cross-sectional shape, stiffness ratio, and mass ratio of the first metal cell, the second metal cell, and the unit cell that satisfy the band gap characteristics representing the band gap frequency derived from the dispersion curve.

[0011] A third aspect of the present disclosure provides a manufacturing system for a vibration damping member. The vibration damping member includes a plurality of unit cells, each of which includes a first metal cell and a second metal cell, and the first metal cell and the second metal cell are connected in a first direction perpendicular to the thickness direction. The plurality of unit cells are connected in the first direction, resulting in an alternating arrangement of the first metal cells and the second metal cells. The plurality of unit cells have smooth outer surfaces in the thickness direction. In each of the unit cells, the stiffness of the first metal cell is different from that of the second metal cell, or the mass per unit length in the first direction of the first metal cell is different from that of the second metal cell, or the stiffness of the first metal cell is different from that of the second metal cell, and the mass per unit length in the first direction of the first metal cell is different from that of the second metal cell. The manufacturing system for a vibration damping member includes a dispersion curve acquisition unit that acquires a dispersion curve representing the relationship between frequency and wave number of the vibration damping member. The vibration suppression member manufacturing system includes a parameter identification unit that identifies parameters including at least one selected from the group consisting of Young's modulus, density, length, cross-sectional shape, stiffness ratio, and mass ratio of the first metal cell, the second metal cell, and the unit cell that satisfy the band gap characteristics representing the band gap frequency derived from the dispersion curve. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide a vibration damping member that has a band gap and has improved applicability as a structural member, a method for manufacturing a vibration damping member, and a system for manufacturing a vibration damping member. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a cross-sectional view illustrating an example of a vibration suppressing member according to an embodiment. [Figure 2] 1 is a cross-sectional view illustrating an example of a manufacturing system for a vibration damping member according to an embodiment. [Figure 3] This is the dispersion curve for a unit cell when the stiffness ratio s is 0.9 and the mass ratio m is 0.1. [Figure 4]10 is a graph showing the relationship between the rigidity ratio and the mass ratio in a unit cell in which the shape of the first metal cell and the shape of the second metal cell are the same, but the metal material of the first metal cell and the metal material of the second metal cell are different. [Figure 5] 10 is a graph showing the relationship between the rigidity ratio and the mass ratio in a unit cell in which the shape of the first metal cell and the shape of the second metal cell are different and the metal material of the first metal cell and the metal material of the second metal cell are the same. [Figure 6] 10 is a graph showing the relationship between the rigidity ratio and the mass ratio in a unit cell in which the shape of the first metal cell is different from the shape of the second metal cell and the metal material of the first metal cell is different from the metal material of the second metal cell. [Figure 7] This is the dispersion curve for a unit cell with Lcx=80 mm. [Figure 8] This is the dispersion curve for a unit cell with Lcx=100 mm. [Figure 9] This is the dispersion curve for a unit cell with Lcx=120 mm. [Figure 10] This is the dispersion curve for a unit cell with Lcx=140 mm. [Figure 11] This is the dispersion curve for a unit cell with Lcx=160 mm. [Figure 12] This is the dispersion curve for a unit cell with Lcx=180 mm. [Figure 13] This is the dispersion curve for a unit cell with Lax:Lbx=9:1. [Figure 14] This is the dispersion curve for a unit cell with Lax:Lbx=8:2. [Figure 15] This is the dispersion curve for a unit cell with Lax:Lbx=7:3. [Figure 16] This is the dispersion curve for a unit cell with Lax:Lbx=6:4. [Figure 17] This is the dispersion curve for a unit cell with Lax:Lbx=5:5. [Figure 18] This is the dispersion curve for a unit cell with Lax:Lbx=4:6. [Figure 19]This is the dispersion curve for a unit cell with Lax:Lbx=3:7. [Figure 20] This is the dispersion curve for a unit cell with Lax:Lbx=2:8. [Figure 21] This is the dispersion curve for a unit cell with Lax:Lbx=1:9. DETAILED DESCRIPTION OF THE INVENTION

[0014] The vibration damping member according to this embodiment will be described in detail below with reference to the drawings. The present disclosure is not limited to the following embodiment. Furthermore, some or all of the components in the embodiment can be combined as appropriate. Note that the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions.

[0015] [1. Vibration suppression material] 1, the vibration suppression member 1 according to this embodiment includes a plurality of unit cells 10. The plurality of unit cells 10 may be 2 or more, 3 or more, 5 or more, 10 or more, 50 or more, or 100 or more unit cells 10. The plurality of unit cells 10 may be 1000 or less, 500 or less, 100 or less, or 10 or less unit cells 10.

[0016] The plurality of unit cells 10 includes a first metal cell 11 and a second metal cell 12. In each unit cell 10, the first metal cells 11 and the second metal cells 12 are connected in a first direction X perpendicular to the thickness direction Z. By connecting the plurality of unit cells 10 in the first direction X perpendicular to the thickness direction Z, the first metal cells 11 and the second metal cells 12 are arranged alternately. In other words, in adjacent unit cells 10, the first metal cell 11 of one unit cell 10 and the second metal cell 12 of the other unit cell 10 are connected in the first direction X.

[0017] In this embodiment, an example will be described in which the first metal cell 11 and the second metal cell 12 are rectangular parallelepipeds. That is, in this embodiment, the first metal cell 11 and the second metal cell 12 are elongated. In this embodiment, an example will be described in which the first metal cell 11 and the second metal cell 12 have the same shape and are both rectangular parallelepipeds having a length, width, and thickness, but the first metal cell 11 and the second metal cell 12 may have the same size and shape or different sizes and shapes.

[0018] In this specification, the first direction X is the longitudinal direction of the first metal cell 11. The second direction Y, which is perpendicular to the first direction X, is the lateral direction of the first metal cell 11. The third direction Z, which is perpendicular to the first direction X and the second direction Y, is the thickness direction Z of the first metal cell 11. The length of the first metal cell 11 in the first direction X is Lax, the length in the second direction Y is Lay, and the length in the third direction Z is Laz. The length of the second metal cell 12 in the first direction X is Lbx, the length in the second direction Y is Lby, and the length in the third direction Z is Lbz. The term "elongated" means that the length in the first direction X, which is the length of the longest portion of the first metal cell 11 or the second metal cell 12, is longer than the length in the second direction Y.

[0019] The shapes of first metal cell 11 and second metal cell 12 are not limited to these shapes and may be, for example, a rectangular prism, a cylinder, or a flat plate. Furthermore, since first metal cell 11 and second metal cell 12 are rectangular parallelepipeds, unit cell 10 is also a rectangular parallelepiped. However, the shape of unit cell 10 is not limited to these shapes and may be, for example, a polygonal pillar, a polygonal cylinder, a cylinder, or a flat plate.

[0020] The unit cells 10 each have a smooth outer surface 15 on the outermost side in the thickness direction Z. For example, if the surface has an uneven shape, as in the periodic structure plate of Patent Document 1, the surface shape changes due to the repetition of concave and convex portions. Therefore, when a load is applied in the thickness direction Z, stress may concentrate in the concave portions, making fatigue failure more likely to occur. On the other hand, the vibration suppression member 1 according to this embodiment has a smooth outer surface 15, and the outer surfaces 15 on both sides along the first direction X are smooth. Therefore, the outer surface 15 does not have unevenness that would cause fatigue failure, and stress concentration due to the uneven shape can be reduced.

[0021] Furthermore, the vibration damping member 1 according to this embodiment has a smooth outer surface 15, which provides a high level of design, and is easy to clean and maintain, as the surface is resistant to dirt. Furthermore, the vibration damping member 1 according to this embodiment is easy to place flatly in relation to other components, or in relation to multiple vibration damping members 1, providing excellent installability. Therefore, compared to conventional structural members with uneven surfaces, the vibration damping member 1 according to this embodiment has improved applicability as a structural member, including design, maintainability, and installability.

[0022] In the rectangular parallelepiped unit cell 10 shown in FIG. 1 , the outermost outer surface 15 in the thickness direction Z is a surface that extends in the first direction X and the second direction Y and is perpendicular to the thickness direction Z. However, as described above, the shape of the unit cell 10 may be a rectangular tube, a cylinder, a flat plate, or the like. The outermost outer surface 15 in the thickness direction Z may be a flat shape, a curved shape, or a combination of these shapes. The shape of the unit cell 10 may be a solid structure or a hollow structure, as described below.

[0023] Here, a smooth surface means that the unit cells 10 are substantially free of large irregularities and steps, and are smooth enough to not pose a problem in applicability as a structural member. For example, when unit cells 10 are connected to each other by welding, a bead may be formed, but it is sufficient that the surface is smooth enough to not pose a problem in applicability as a structural member. It has been confirmed that even when unit cells 10 are connected to each other by welding, the bandgap characteristics are not significantly affected. Therefore, it is sufficient that the outer surface 15 is smooth enough not to affect the stiffness ratio and mass ratio. Furthermore, for example, even when the first metal cell 11 and the second metal cell 12 are connected to each other by welding, it is sufficient that the surface is smooth enough to not pose a problem in applicability as a structural member.

[0024] In each unit cell 10, the rigidity of the first metal cell 11 and the rigidity of the second metal cell 12 may be different, or the mass per unit length in the first direction X of the first metal cell 11 may be different from the mass per unit length in the first direction X of the second metal cell 12, or the rigidity of the first metal cell 11 and the rigidity of the second metal cell 12 may be different and the mass per unit length in the first direction X of the first metal cell 11 may be different from the mass per unit length in the first direction X of the second metal cell 12. By making at least one of the rigidity and mass of the first metal cell 11 and the second metal cell 12 different, a vibration suppressing member 1 having a band gap can be provided. Note that in each unit cell 10, the rigidity of the first metal cell 11 may be higher or lower than the rigidity of the second metal cell 12. The mass per unit length in the first direction X of the first metal cell 11 may be higher or lower than the mass per unit length in the first direction X of the second metal cell 12. In this specification, the rigidity refers to bending rigidity, which can be calculated as the product of Young's modulus E and the moment of inertia I.

[0025] The vibration suppressing member 1 may be formed by connecting one type of unit cells 10, in which the first metal cells 11 and the second metal cells 12 are different in at least one of rigidity and mass. Alternatively, the vibration suppressing member 1 may be formed by connecting multiple types of unit cells 10, in which the first metal cells 11 and the second metal cells 12 are different in at least one of rigidity and mass.

[0026] In each unit cell 10, the internal structure of the first metal cell 11 may be different from the internal structure of the second metal cell 12. Even with this configuration, it is possible to provide a vibration damping member 1 having a band gap by making at least one of the rigidity and mass of the first metal cell 11 and the second metal cell 12 different while maintaining the smooth shape of the outer surface 15. In other words, it is preferable to select a combination of internal structures that results in a difference in at least one of the rigidity and mass, with the rigidity and mass determined by the internal structures of the first metal cell 11 and the second metal cell 12.

[0027] The first metal cell 11 may have a solid structure or a hollow structure. Similarly, the second metal cell 12 may have a solid structure or a hollow structure. A solid structure is a structure that does not have a hollow portion. A hollow structure is a structure that has at least one hollow portion.

[0028] The first metal cell 11 may have a solid structure and the second metal cell 12 may have a hollow structure. Alternatively, the first metal cell 11 may have a hollow structure and the second metal cell 12 may have a solid structure. With such a configuration, it is possible to provide a vibration damping member 1 having a band gap.

[0029] The solid structure may include, for example, at least one selected from the group consisting of a cylindrical structure, a polygonal pillar structure, an E-shaped structure, an H-shaped structure, an I-shaped structure, an M-shaped structure, an N-shaped structure, a U-shaped structure, and a Z-shaped structure. The cylindrical structure may include a structure having a circular cross-sectional shape, such as an oval, a perfect circle, or an ellipse, when viewed from the first direction X. The polygonal pillar structure may include a structure having a polygonal cross-sectional shape, such as a quadrangle, when viewed from the first direction X. The E-shaped structure, H-shaped structure, I-shaped structure, M-shaped structure, N-shaped structure, U-shaped structure, and Z-shaped structure may include a structure having an E-shaped, H-shaped, I-shaped, M-shaped, N-shaped, U-shaped, and Z-shaped cross-sectional shape, respectively, when viewed from the first direction X, and extending continuously and linearly in the first direction.

[0030] The hollow structure may include, for example, at least one selected from the group consisting of a cylindrical structure, a harmonica structure, a truss structure, a honeycomb structure, a lattice structure, a mesh structure, and a porous structure. These structures may be formed continuously in the first direction X or may be formed continuously in the thickness direction Z. From the viewpoint of ease of extrusion molding, these structures are preferably formed continuously and linearly in the first direction X.

[0031] Second metal cell 12 may have at least one structure selected from the group consisting of an E-shaped structure, an H-shaped structure, an I-shaped structure, an M-shaped structure, an N-shaped structure, a U-shaped structure, a Z-shaped structure, a cylindrical structure, a harmonica structure, a truss structure, a honeycomb structure, a lattice structure, a mesh structure, and a porous structure. In this case, first metal cell 11 may have at least one structure selected from the group consisting of a cylindrical structure and a polygonal prism structure. Even with this configuration, a vibration damping member 1 having a band gap can be provided by making at least one of the rigidity and mass of first metal cell 11 and second metal cell 12 different.

[0032] Due to their high torsional rigidity, the first metal cell 11 or the second metal cell 12 preferably has at least one structure selected from the group consisting of a harmonica structure, a truss structure, a honeycomb structure, and a lattice structure. Meanwhile, cylindrical structures, polygonal prism structures, E-shaped structures, H-shaped structures, I-shaped structures, M-shaped structures, N-shaped structures, U-shaped structures, Z-shaped structures, harmonica structures, truss structures, and honeycomb structures are easily extrusion molded and therefore suitable for mass production. Among these, the harmonica structure and truss structure are particularly suitable for mass production because they are easily extrusion molded as hollow structures. At least one hollow structure selected from the group consisting of a harmonica structure, a truss structure, a honeycomb structure, a lattice structure, a mesh structure, and a porous structure can also be formed using a 3D printer. Porous structures can be formed by foaming a material containing a foaming agent or by baking metal particles.

[0033] In each unit cell 10, the metal material of the first metal cell 11 may be different from the metal material of the second metal cell 12. Even with this configuration, it is possible to provide a vibration suppression member 1 having a band gap while maintaining the smooth shape of the surfaces on both sides of the unit cell 10.

[0034] First metal cell 11 is formed of a metal material. The metal material contained in first metal cell 11 may include at least one selected from the group consisting of iron, copper, titanium, aluminum, and magnesium. The metal material contained in first metal cell 11 may be iron, copper, titanium, aluminum, magnesium, an alloy thereof, or a combination of these metals.

[0035] The second metal cell 12 is formed of a metal material. The second metal cell 12 can use the same metal material as the first metal cell 11. That is, the metal material contained in the second metal cell 12 may contain at least one selected from the group consisting of iron, copper, titanium, aluminum, and magnesium. The metal material contained in the second metal cell 12 may be iron, copper, titanium, aluminum, magnesium, an alloy thereof, or a combination of these metals. The metal material of the first metal cell 11 and the metal material of the second metal cell 12 may be the same or different. Note that an example of an alloy containing iron is steel.

[0036] The first metal cell 11 may be at least one selected from the group consisting of aluminum, magnesium, iron, copper, titanium, alloys of these metals, and steel. The second metal cell 12 may be at least one selected from the group consisting of aluminum, magnesium, titanium, and alloys of these metals. By combining the first metal cell 11 and the second metal cell 12 in this manner, the smooth surfaces of both sides of the unit cell 10 can be maintained while the first metal cell 11 and the second metal cell 12 have different rigidities and masses, thereby providing a vibration damping member 1 having a band gap. In other words, it is preferable to select a combination of metal materials that differ in at least one of the rigidity and mass, while the rigidity and mass are determined by the metal materials forming the first metal cell 11 and the second metal cell 12. Iron, copper, titanium, alloys of these metals, and steel are also preferred for the first metal cell 11. Titanium has characteristics such as a high Young's modulus and light weight, and these characteristics can be taken into consideration when using titanium for the first metal cell 11 or the second metal cell 12.

[0037] In each unit cell 10, the internal structure of the first metal cell 11 and the internal structure of the second metal cell 12 may be different, and the metal material of the first metal cell 11 may be different from the metal material of the second metal cell 12. With this configuration, it is possible to select a wider variety of combinations of stiffness ratios and mass ratios than when only the internal structures of the first metal cell 11 and the second metal cell 12 are different or when only the materials of the first metal cell 11 and the second metal cell 12 are different. This improves the design freedom of the vibration suppression member 1.

[0038] The first metal cell 11 may be made of steel, and the second metal cell 12 may be made of an aluminum alloy, with the first metal cell 11 having a solid structure and the second metal cell 12 having a hollow structure. For the first metal cell 11 and the second metal cell 12, a combination of steel and an aluminum alloy that results in a large difference in Young's modulus and density is used, and by making the first metal cell 11 solid and the second metal cell 12 hollow, the rigidity ratio s and mass ratio m between the first metal cell 11 and the second metal cell 12 can be increased. This makes it possible to obtain a vibration suppression member 1 using unit cells 10 having a predetermined rigidity ratio s and mass ratio m, as described below.

[0039] In this specification, the rigidity ratio s represents the ratio (s2 / s1) of the rigidity s2 of the second metal cell 12 to the rigidity s1 of the first metal cell 11. The mass ratio m represents the ratio (m2 / m1) of the mass m2 of the second metal cell 12 per unit length in the first direction X to the mass m1 of the first metal cell 11 per unit length in the first direction X.

[0040] And, when the stiffness ratio is s and the mass ratio is m, 0.01≦s / m<1 and 1 ​Note that as s / m calculated from the rigidity ratio s and the mass ratio m increases, that is, as the rigidity ratio s increases with respect to the mass ratio m (increasing so as to deviate from 1), the bandwidth of the band gap (especially the first band gap) tends to widen. For this reason, it is more preferable to satisfy the requirement of 2 ≤ s / m ≤ 100, even more preferable to satisfy the requirement of 5 ≤ s / m ≤ 100, and particularly preferable to satisfy the requirement of 10 ≤ s / m ≤ 100. Further, as s / m calculated from the rigidity ratio s and the mass ratio m decreases, that is, as the rigidity ratio s decreases with respect to the mass ratio m (decreasing so as to deviate from 1), the bandwidth of the band gap (especially the first band gap) tends to widen. For this reason, it is more preferable to satisfy the requirement of 0.01 ≤ s / m < 0.5, even more preferable to satisfy the requirement of 0.05 ≤ s / m < 0.4, and particularly preferable to satisfy the requirement of 0.1 ≤ s / m < 0.3.

[0041] Further, when the rigidity ratio is s and the mass ratio is m, it is preferable to satisfy the requirements of 0.01 ≤ s ≤ 100 and 0.01 ≤ m ≤ 100 (however, excluding 0.8 < s < 1 / 0.9 and 0.9 < m < 1 / 0.9). In this way, the rigidity of the first metal cell 11 and the rigidity of the second metal cell 12 take different numerical ranges by the rigidity ratio s deviating from around 1, and the mass of the first metal cell 11 and the mass of the second metal cell 12 take different numerical ranges by the mass ratio m deviating from around 1, which is preferable. Even when the rigidity ratio s and the mass ratio m are within the above ranges, it is possible to provide the vibration suppression member 1 having a better band gap (especially the second band gap). Note that when the mass ratio m is 0.2 or less, the bandwidth of the band gap (especially the second band gap) tends to widen within a wide range of the rigidity ratio s. For this reason, it is more preferable to satisfy the requirements of 0.01 ≤ s ≤ 100 and 0.01 ≤ m ≤ 0.2, even more preferable to satisfy the requirements of 0.05 ≤ s ≤ 20 and 0.02 ≤ m ≤ 0.15, and particularly preferable to satisfy the requirements of 0.1 ≤ s ≤ 10 and 0.05 ≤ m ≤ 0.1. Also, when the rigidity ratio s is 5 or more, the bandwidth of the band gap (especially the second band gap) tends to become wider within a wide range of the mass ratio m. Therefore, it is more preferable to satisfy the requirements of 5 ≤ s ≤ 100 and 0.01 < m ≤ 100, even more preferable to satisfy the requirements of 7.5 ≤ s ≤ 100 and 0.05 < m ≤ 20, and particularly preferable to satisfy the requirements of 10 ≤ s ≤ 20 and 0.1 < m ≤ 10.

[0042] In addition, when the above rigidity ratio is s and the above mass ratio is m, it is also preferable to satisfy the requirements of 0.6 ≤ s ≤ 100 and 从0.01 ≤ m ≤ 0.3. Thus, it is preferable that the rigidity ratio s takes a numerical range of 0.6 or more and the mass ratio m takes a numerical range of 0.3 or less even when the rigidity ratio s and the mass ratio m are within the above ranges, it is possible to provide the vibration suppression member 1 having a better band gap (especially the first band gap and the second band gap). Note that as the rigidity ratio s increases and the mass ratio m decreases, the bandwidth of the band gap (especially the first band gap and the second band gap) tends to become wider. Therefore, it is more preferable to satisfy the requirements of 0.8 ≤ s ≤ 100 and 0.01 ≤ m ≤ 0.2, even more preferable to satisfy the requirements of 1 ≤ s ≤ 20 and 0.02 ≤ m ≤ 0.15, and particularly preferable to satisfy the requirements of 2 ≤ s ≤ 10 and 0.05 ≤ m ≤ 0.1.

[0043] The stiffness ratio s may be 0.1 or greater and 10 or less. When the stiffness ratio s is within the above range, a vibration damping member 1 having an even better band gap can be provided. From the viewpoint of widening the band gap, the stiffness ratio s may be 0.2 or greater, 0.3 or greater, 0.4 or greater, 0.5 or greater, 0.6 or greater, 0.7 or greater, 0.8 or greater, 0.9 or greater, 1.0 or greater, 1 / 0.9 or greater, 1 / 0.8 or greater, 1 / 0.7 or greater, 1 / 0.6 or greater, 1 / 0.5 or greater, 1 / 0.4 or greater, 1 / 0.3 or greater, 1 / 0.2 or greater, or 1 / 0.1 or greater. The rigidity ratio s may be 1 / 0.1 or less, 1 / 0.2 or less, 1 / 0.3 or less, 1 / 0.4 or less, 1 / 0.5 or less, 1 / 0.6 or less, 1 / 0.7 or less, 1 / 0.8 or less, 1 / 0.9 or less, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, or 0.2 or less.

[0044] The mass ratio m may be 0.1 or more and 10 or less. When the mass ratio m is within the above range, a vibration damping member 1 having an even better band gap can be provided. From the viewpoint of widening the band gap, the mass ratio m may be 1 / 0.1 or less, 1 / 0.2 or less, 1 / 0.3 or less, 1 / 0.4 or less, 1 / 0.5 or less, 1 / 0.6 or less, 1 / 0.7 or less, 1 / 0.8 or less, 1 / 0.9 or less, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, or 0.2 or less. The mass ratio m may be 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1 / 0.9 or more, 1 / 0.8 or more, 1 / 0.7 or more, 1 / 0.6 or more, 1 / 0.5 or more, 1 / 0.4 or more, 1 / 0.3 or more, 1 / 0.2 or more, or 1 / 0.1 or more.

[0045] The vibration damping member 1 may have a bandgap center frequency in the range of 10 Hz to 6000 Hz. The bandgap center frequency may be 200 Hz or more, 300 Hz or more, 400 Hz or more, 600 Hz or more, 800 Hz or more, 1000 Hz or more, or 2000 Hz or more. The bandgap center frequency may be 6000 Hz or less, 3000 Hz or less, 1500 Hz or less, or 1000 Hz or less. The bandgap center frequency may be the center frequency of the first bandgap or the center frequency of the second bandgap. For example, the first bandgap center frequency may be 10 Hz or more and 1500 Hz or less. The second bandgap center frequency may be 200 Hz or more and 6000 Hz or less.

[0046] The band gap bandwidth may be 0.1 Hz or more and 5000 Hz or less. A wider band gap bandwidth is preferable, and may be 1 Hz or more, 10 Hz or more, 100 Hz or more, 200 Hz or more, 400 Hz or more, 600 Hz or more, 800 Hz or more, 1000 Hz or more, 1500 Hz or more, or 2000 Hz or more. The band gap bandwidth may be 4000 Hz or less, 3000 Hz or less, 2000 Hz or less, or 1000 Hz or less. The band gap bandwidth may be the bandwidth of a first band gap or the bandwidth of a second band gap.

[0047] When the rigidity of the first metal cell 11 is s1 and the rigidity of the second metal cell 12 is s2, s1 may be greater than s2. Furthermore, when the mass per unit length in the first direction X of the first metal cell 11 is m1 and the mass per unit length in the first direction X of the second metal cell 12 is m2, m1 may be greater than m2. The ratio of the length of the first metal cell 11 in the first direction X to the length of the second metal cell 12 in the first direction X may be greater than 1 / 9 and less than 8 / 2. In this way, when the rigidity s1 and mass m1 of the first metal cell 11 are greater than the rigidity s2 and mass m2 of the second metal cell 12, the first metal cells 11 with high rigidity and density and the second metal cells 12 with lower rigidity and density than the first metal cells 11 are alternately present. In this case, by setting the ratio of the length of the first metal cell 11 to the length of the second metal cell 12 within the above range, the second metal cells with low rigidity and density are present among the first metal cells 11 with high rigidity and density. Therefore, first metal cell 11 and second metal cell 12 become non-uniform, and the specificity between first metal cell 11 and second metal cell 12 increases, thereby widening the bandgap width. The ratio of the length of first metal cell 11 to the length of second metal cell 12 may be 2 / 8 or more, 3 / 7 or more, or 4 / 6 or more. The ratio of the length of first metal cell 11 to the length of second metal cell 12 may be 7 / 3 or less, 6 / 4 or less, or 5 / 5 or less.

[0048] The length Lcx of the unit cell 10 in the first direction X may be 10 mm or more and 100 mm or less. By setting the length Lcx of the unit cell 10 within the above range, the band width of the band gap can be widened. The length Lcx of the unit cell 10 may be 20 mm or more, 30 mm or more, or 50 mm or more. Furthermore, the length Lcx of the unit cell 10 may be 80 mm or less, 60 mm or less, or 40 mm or less.

[0049] The vibration damping member 1 has a band gap, which improves its applicability as a structural member. Therefore, the vibration damping member 1 may be used as a vehicle member, an aircraft member, a residential member, or a building member. Examples of vehicles include bullet trains, trains, buses, private cars, and trucks. The vibration damping member 1 can also be used in dash panels, floor panels, hoods, composite beams, and the like.

[0050] The vibration suppression member 1 may have a single band gap, or may have two or more band gaps. When the vibration suppression member 1 has two or more band gaps, the band gaps are numbered in order from lowest frequency to highest frequency, such as first band gap, second band gap, third band gap, and so on.

[0051] <Action and effect> The vibration suppression member 1 according to this embodiment includes a plurality of unit cells 10, each of which includes a first metal cell 11 and a second metal cell 12. The first metal cells 11 and the second metal cells 12 are connected in a first direction X perpendicular to the thickness direction Z. The unit cells 10 are connected in the first direction X, so that the first metal cells 11 and the second metal cells 12 are alternately arranged. The unit cells 10 have smooth outer surfaces 15 extending outward from each other in the thickness direction Z. In each of the unit cells 10, the rigidity of the first metal cell 11 and the rigidity of the second metal cell 12 may be different, or the mass per unit length in the first direction X of the first metal cell 11 may be different from the mass per unit length in the first direction X of the second metal cell 12, or the rigidity of the first metal cell 11 and the rigidity of the second metal cell 12 may be different, and the mass per unit length in the first direction X of the first metal cell 11 may be different from the mass per unit length in the first direction X of the second metal cell 12.

[0052] Furthermore, in the vibration suppression member 1 according to this embodiment, at least one of the rigidity and mass of the first metal cell 11 and the second metal cell 12 is different. With this configuration, it is possible to provide a vibration suppression member 1 having a band gap. Furthermore, by making at least one of the rigidity and mass of the first metal cell 11 and the second metal cell 12 different, it is possible to provide a vibration suppression member 1 having a band gap, and therefore it is possible to provide a vibration suppression member 1 with a high degree of freedom in design.

[0053] In the vibration suppression member 1 according to this embodiment, the outermost outer surface 15 in the thickness direction Z of the multiple unit cells 10 is smooth. Therefore, the outer surface 15 does not have unevenness that would cause fatigue failure, which reduces stress concentration due to the uneven shape. Furthermore, because the outer surface 15 is smooth, it has a high designability, is resistant to dirt, and is easy to clean, making it easy to maintain. Furthermore, because the outer surface 15 is smooth, the vibration suppression member 1 can be easily placed flat, making it easy to install. Therefore, compared to conventional structural members with uneven surfaces, the vibration suppression member 1 according to this embodiment has improved applicability as a structural member.

[0054] Therefore, it is possible to provide a vibration suppressing member 1 that has a band gap and has improved applicability as a structural member.

[0055] [2. Manufacturing method of vibration suppression member] Next, a description will be given of a method for manufacturing the vibration damping member 1 according to this embodiment. The method for manufacturing the vibration damping member 1 according to this embodiment includes a dispersion curve acquisition step and a specification step.

[0056] <Dispersion curve acquisition step> The dispersion curve acquisition step is a process of acquiring a dispersion curve according to the parameters.

[0057] The parameters include at least one selected from the group consisting of Young's modulus, density, length, cross-sectional shape, stiffness ratio, and mass ratio of a cell including at least one selected from the group consisting of first metal cell 11, second metal cell 12, and unit cell 10. The lengths included in the parameters may include a length Lax of first metal cell 11 in the first direction X, a length Lay of first metal cell 11 in the second direction Y, a length Laz of first metal cell 11 in the third direction Z, a length Lbx of second metal cell 12 in the first direction X, a length Lby of second metal cell 12 in the second direction Y, a length Lbz of second metal cell 12 in the third direction Z, a length Lcx of unit cell 10 in the first direction X, a length Lcy of unit cell 10 in the second direction Y, and a length Lcz of unit cell 10 in the third direction Z.

[0058] The dispersion curve represents the relationship between the frequency (angular frequency ω) and wave number k of the vibration suppression member 1. The dispersion curve does not depend on the number of repetitions of the unit cells 10, but depends only on the characteristics of the unit cells 10. Therefore, the dispersion curve may represent the dispersion relationship, which is the relationship between the frequency (angular frequency ω) of the unit cells 10 and the wave number k of the unit cells 10. The dispersion curve can be used to confirm the formation of a band gap in the vibration suppression member 1. If the vibration suppression member 1 has a band gap, vibrations transmitted through the vibration suppression member 1 are suppressed.

[0059] The dispersion curve can be obtained, for example, by calculating the wave number k of the unit cell 10 using the WAVE FINITE ELEMENT method (WFEM: see S. Tomita et al., “Elastic metamaterial composite made of molded pulp and steel for suppression of low-frequency vibration in thin-plate structures,” Materials & Design, November 2022, Vol. 223).

[0060] Specifically, the wave number k of the unit cell 10 can be calculated at a certain angular frequency ω from the propagation coefficient λ calculated as an eigenvalue of the transfer matrix T using the following equation (1). The transfer matrix T can be calculated using the dynamic stiffness matrix D of the unit cell 10. The propagation coefficient λ can represent the displacement and internal force within the unit cell 10. The eigenvalue λ is calculated by solving the eigenvalue problem between the transfer matrix T and the propagation coefficient λ at a certain angular frequency ω. By repeating this calculation, a dispersion curve representing the dispersion relationship between the angular frequency ω and the wave number k can be obtained. In a dispersion curve, the wave number is generally expressed as a complex number, with the real part of the wave number representing wave propagation and the imaginary part of the wave number representing wave attenuation. The frequency at which the imaginary part takes a negative value is called the cutoff frequency, and this cutoff frequency corresponds to the band gap. Therefore, by calculating the dispersion curve and examining the conditions under which the wave number becomes a complex number, the formation of a band gap can be determined. However, this disclosure deals with the dispersion relationship between the frequency f = ω / 2π and the wave number k, rather than the angular frequency ω.

[0061]

number

[0062] In the above formula (1), k represents the wave number, j represents the imaginary unit, λ represents the propagation coefficient, and Lcx represents the length of the unit cell 10.

[0063] In addition to WFEM, dispersion curves can also be obtained using the Differential Quadrature Method (DQM: see H. Xiang and Z. Shi, “Analysis of flexural vibration band gaps in periodic beams using differential quadrature method,” Computers & Structures, December 2009, Vol. 87, pp. 1559-1566) and the energy method (see L. Tang and L. Cheng, “Broadband locally resonant band gaps in periodic beam structures with embedded acoustic black holes,” Journal of applied physics, May 2017, Vol. 121, Issue 19).

[0064] <Specific step> In the identification step, parameters including at least one selected from the group consisting of Young's modulus, density, length, cross-sectional shape, stiffness ratio, and mass ratio of the first metal cell 11, the second metal cell 12, and the unit cell 10 are identified to satisfy the bandgap characteristics representing the frequency of the bandgap.

[0065] The bandgap characteristics represent the frequency of the bandgap derived from the dispersion curve, and more specifically, can be represented by the lower and upper limit frequencies of the bandgap, or the center frequency and bandgap width (bandwidth). The bandgap bandwidth may include at least one of a first bandwidth representing the bandgap width of a first bandgap and a second bandwidth representing the bandgap width of a second bandgap. The frequency at which the bandgap occurs may include at least one of a first frequency representing the frequency at which the first bandgap occurs and a second frequency representing the frequency at which the second bandgap occurs. Note that although the present specification refers to the first and second bandgap characteristics, the bandgap characteristics may also include third or more bandgap characteristics.

[0066] The identifying step may involve creating a map showing the relationship (combination) between the bandgap characteristics obtained by varying the parameters in the dispersion curve and the parameters, and identifying the parameters from the map. This allows identifying parameters that match the desired bandgap characteristics included in the map. Examples of the desired bandgap characteristics include those with high, low, highest, or lowest bandgap characteristics values, those within a predetermined range, or those outside a predetermined range. For example, parameters that result in a low lower limit frequency of the bandgap, a high upper limit frequency of the bandgap, a high center frequency of the bandgap, a low center frequency of the bandgap, a wide bandgap bandwidth, or a bandgap at a desired frequency can be identified. In this way, a vibration suppression member 1 capable of suppressing vibrations with desired frequency characteristics can be provided.

[0067] In the identification step, a map may be created that shows the relationship between the bandgap characteristics obtained by changing the stiffness ratio and mass ratio on the dispersion curve and the stiffness ratio and mass ratio, and the stiffness ratio and mass ratio may be identified from this map. This allows the stiffness ratio and mass ratio that match the desired bandgap characteristics to be identified. For example, it is possible to identify the stiffness ratio and mass ratio that result in a wide bandgap width or a bandgap at a target frequency. This makes it possible to provide a vibration suppression member 1 that can suppress desired vibrations.

[0068] In the identifying step, a map may be created that represents the relationship between the bandgap characteristics obtained by changing the length of the unit cell 10 in the first direction X on the dispersion curve and the length of the unit cell 10 in the first direction X, and the length of the unit cell 10 in the first direction X may be identified from this map. This makes it possible to identify the length of the unit cell 10 in the first direction X that matches the desired bandgap characteristics. For example, it is possible to identify the length in the first direction X of the unit cell 10 that provides a wide bandgap bandwidth or a bandgap at a target frequency. This makes it possible to provide a vibration suppression member 1 that can suppress desired vibrations.

[0069] In the specifying step, a map may be created that shows the relationship between the bandgap characteristics obtained by changing the lengths of the first metal cell 11 and the second metal cell 12 in the first direction X on the dispersion curve and the lengths of the first metal cell 11 and the second metal cell 12 in the first direction X, and the lengths of the first metal cell 11 and the second metal cell 12 in the first direction X may be specified from the map. This makes it possible to specify the lengths of the first metal cell 11 and the second metal cell 12 in the first direction X that match the desired bandgap characteristics. For example, it is possible to specify the lengths of the first metal cell 11 and the second metal cell 12 in the first direction X that provide a wide bandgap bandwidth or a bandgap at a target frequency. This makes it possible to provide a vibration suppression member 1 that can suppress desired vibrations.

[0070] <Action and effect> The method for manufacturing vibration suppression member 1 according to this embodiment includes a dispersion curve acquisition step for acquiring a dispersion curve that represents the relationship between frequency and wavenumber of vibration suppression member 1. The method for manufacturing vibration suppression member 1 also includes a specification step for identifying parameters including at least one selected from the group consisting of Young's modulus, density, length, cross-sectional shape, stiffness ratio, and mass ratio of first metal cell 11, second metal cell 12, and unit cell 10, which satisfy the bandgap characteristics that represent the frequency of the bandgap derived from the dispersion curve. Therefore, the method for manufacturing vibration suppression member 1 according to this embodiment makes it possible to manufacture a vibration suppression member 1 that has a bandgap and has improved applicability as a structural member.

[0071] [3. Manufacturing system for vibration suppression components] Next, a manufacturing system for the vibration damping member 1 according to this embodiment will be described. The manufacturing system for the vibration damping member 1 is a system for carrying out the manufacturing method for the vibration damping member 1 described above.

[0072] As shown in FIG. 2, the manufacturing system 100 for the vibration damping member 1 includes a general computer 110 , which includes an input unit 111 , a storage unit 112 , a calculation unit 113 , and an output unit 114 .

[0073] To the input unit 111, parameters including at least one selected from the group consisting of Young's modulus, density, length, cross-sectional shape, stiffness ratio, and mass ratio of a cell including at least one selected from the group consisting of first metal cell 11, second metal cell 12, and unit cell 10 are input. The input unit 111 includes input devices such as a keyboard and a mouse, and the computer 110 is operated by a user inputting instructions to the input unit 111.

[0074] The storage unit 112 stores a program for identifying parameters and data referenced in the execution of the program. The storage unit 112 may also store information related to a map representing the relationship between the bandgap characteristics and the parameters. The storage unit 112 may include a recording medium such as a random access memory (RAM) used as a main storage device and a read-only memory (ROM) used as an auxiliary storage device. The recording medium may also be an external recording medium such as an optical disk, such as a compact disc read-only memory (CD-ROM) or a digital versatile disc read-only memory (DVD-ROM); a universal serial bus (USB) memory, or a flash memory, such as an SD memory.

[0075] The program reads out information stored in the storage unit 112 and outputs parameters identified based on the read out information. The program is a program for causing the computer 110 to execute the dispersion curve acquisition step and the identification step.

[0076] The calculation unit 113 includes a dispersion curve acquisition unit 113a that acquires a dispersion curve and a parameter identification unit 113b that identifies parameters. Specifically, in the calculation unit 113, the dispersion curve acquisition unit 113a acquires a dispersion curve that represents the relationship between the frequency and wavenumber of the vibration suppression member 1. Then, in the calculation unit 113, the parameter identification unit 113b identifies parameters including at least one selected from the group consisting of Young's modulus, density, length, cross-sectional shape, stiffness ratio, and mass ratio of the first metal cell 11, the second metal cell 12, and the unit cell 10, which satisfy the bandgap characteristics that represent the frequency of the bandgap derived from the dispersion curve. The dispersion curve acquisition unit 113a and the parameter identification unit 113b are stored as programs in the storage unit 112. The calculation unit 113 includes a CPU (Central Processing Unit) that reads the program and reference data stored in the recording medium of the storage unit 112, expands them into the main storage device of the storage unit 112, and executes them to function as the dispersion curve acquisition unit 113a and the parameter identification unit 113b. The calculation unit 113 acquires a dispersion curve by the dispersion curve acquisition unit 113a, and identifies parameters by the parameter identification unit 113b.

[0077] The parameter specifying unit 113b may create a map showing the relationship between the bandgap characteristics obtained by varying the parameters in the dispersion curve and the parameters, and specify the parameters from the map. The parameter specifying unit 113b can specify parameters that match the desired bandgap characteristics included in the map. For example, the parameter specifying unit 113b can specify the parameters by reading the desired bandgap characteristics stored in the storage unit 112 and selecting parameters that match the read desired bandgap characteristics from combinations of bandgap characteristics and parameters included in the map.

[0078] Output unit 114 outputs the parameters of first metal cell 11, second metal cell 12, and unit cell 10 identified by calculation unit 113. Output unit 114 may include a display device such as an LCD monitor or a printer, and outputs the parameters processed by calculation unit 113.

[0079] <Action and effect> The manufacturing system 100 for the vibration damping member 1 according to this embodiment includes a dispersion curve acquisition unit 113a that acquires a dispersion curve that represents the relationship between frequency and wavenumber of the vibration damping member 1. The manufacturing system 100 also includes a parameter identification unit 113b that identifies parameters including at least one selected from the group consisting of Young's modulus, density, length, cross-sectional shape, stiffness ratio, and mass ratio of the first metal cell 11, the second metal cell 12, and the unit cell 10, which satisfy the bandgap characteristics that represent the frequency of the bandgap derived from the dispersion curve. Therefore, the manufacturing system 100 for the vibration damping member 1 according to this embodiment can manufacture a vibration damping member 1 that has a bandgap and has improved applicability as a structural member. [Example]

[0080] Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited to these.

[0081] [Test Example 1] Dispersion curves were obtained by varying the parameters of the first and second metal cells (and the unit cell itself) included in the unit cell, and the influence of these parameters on the bandgap characteristics was evaluated. The bandgap characteristics do not depend on the number of unit cell repetitions, but only on the unit cell characteristics. Therefore, a single unit cell was evaluated, in which the a-phase constituting the first metal cell and the b-phase constituting the second metal cell were connected in the first direction X, as shown in Figure 1. The length Lax of the first metal cell in the first direction X was 60 mm, the length Lay of the second direction Y was 20 mm, and the length Laz of the third direction Z was 3 mm. The length Lbx of the second metal cell in the first direction X was 60 mm, the length Lby of the second direction Y was 20 mm, and the length Lbz of the third direction Z was 3 mm. In the YZ cross section perpendicular to the first direction X, the cross-sectional area Aa of the first metal cell and the cross-sectional area Ab of the second metal cell were both 60 mm. 2 In this example, the length Lcx of the unit cell in the direction in which the first metal cell and the second metal cell are connected is set to 120 mm. The material of the first metal cell has a Young's modulus Ea of 182 GPa and a density ρa of 8020 kg / m 3 The material was maraging steel with a Poisson's ratio of 0.3, and the structure was solid.

[0082] The bandgap frequency trend was investigated by varying the material properties of the second metal cell, namely, Young's modulus Eb and density ρb, as well as the cross-sectional properties of the second metal cell, namely, the cross-sectional area Ab and moment of inertia Iyb. The material properties of the first metal cell, namely, Young's modulus Ea and density ρa, as well as the cross-sectional properties of the first metal cell, namely, the cross-sectional area Aa and moment of inertia Iya, were fixed. Specifically, the stiffness ratio s and mass ratio m were extracted from among many factors as material properties that affect vibration suppression, and their effects were investigated. The stiffness ratio s can be expressed as s = EbIyb / EaIya. The mass ratio m can be expressed as m = ρbAb / ρaAa.

[0083] Figure 3 shows the dispersion curve of a unit cell when the stiffness ratio s is 0.9 and the mass ratio m is 0.1. In Figure 3, the horizontal axis represents frequency, and the vertical axis represents the imaginary part of the wave number divided by 2π. As shown in Figure 3, band gaps appear at frequencies of approximately 490 Hz to 840 Hz and approximately 2300 Hz to 3400 Hz. From this, it is believed that in a unit cell with a stiffness ratio s of 0.9 and a mass ratio m of 0.1, band gaps are formed at frequencies of approximately 490 Hz to 840 Hz and approximately 2300 Hz to 3400 Hz. Of the two observed band gaps, the band gap at the lower frequency of 490 Hz to 840 Hz is referred to as the first band gap. Of the two observed band gaps, the band gap at the higher frequency of 2300 Hz to 3400 Hz is referred to as the second band gap. The first band gap started at 487 Hz, ended at 837 Hz, and had a bandwidth of 350 Hz. The second band gap started at 2345 Hz, ended at 3443 Hz, and had a bandwidth of 1098 Hz. Thus, dispersion curves were evaluated for a total of 361 unit cells, with 19 values ​​of s ranging from 0.1 to 1 / 1.0 and 19 values ​​of m ranging from 0.1 to 1 / 1.0. The evaluation results for the first band gap are shown in Tables 1 to 4, and the evaluation results for the second band gap are shown in Tables 5 to 8. In the tables, the left side of the top row represents the start of the band gap, the right side represents the end of the band gap, and the bottom row represents the bandwidth.

[0084] [Table 1]

[0085] [Table 2]

[0086] [Table 3]

[0087] [Table 4]

[0088] [Table 5]

[0089] [Table 6]

[0090] [Table 7]

[0091] [Table 8]

[0092] As shown in Tables 1 to 4, in the frequency range of 0 kHz to 1 kHz, when the values ​​of s and m are equal (s = m), no first band gap is formed in the unit cell. On the other hand, when the values ​​of s and m are most different, particularly when s is 10 and m is 0.1, the bandwidth is large. In other words, there is a tendency for the bandwidth of the first band gap to increase as the value of s / m becomes more distant from 1.

[0093] As shown in Tables 5 to 8, unlike the first band gap, the second band gap was formed even when s and m were equal (s = m), except when s = 1 and m = 1. It was also found that the bandwidth of the second band gap was large when m was 0.1, indicating a large effect of the mass ratio. The second band gap had the largest bandwidth when s = 10 and m = 0.1, and tended to become smaller as the conditions changed to s = 1 and m = 1. The band gap also tended to shift to the higher frequency side as the stiffness ratio s increased, and to the lower frequency side as the mass ratio m increased. It was also found that the band gap in the low frequency range tended to have a smaller bandwidth than the band gap in the high frequency range.

[0094] [Test Example 2] Next, we evaluated the relationship between the rigidity ratio and the mass ratio for unit cells in which the first and second metal cells had the same shape but the metal materials of the first and second metal cells were different. Specifically, the first metal cell was a rectangular bar (solid structure) with a length Lax of 60 mm, a width of 20 mm, and a thickness of 3 mm. The second metal cell was also a rectangular bar (solid structure) with a length Lbx of 60 mm, a width of 20 mm, and a thickness of 3 mm. The first metal cell was made of aluminum (Al), and the second metal cell was made of steel, titanium (Ti), or copper (Cu). That is, the materials of the first and second metal cells were Steel / Al, Ti / Al, or Cu / Al. As shown in Figure 4, the rigidity ratio and the mass ratio change depending on the combination of the materials of the first and second metal cells.

[0095] [Test Example 3] Next, the relationship between the stiffness ratio and the mass ratio was evaluated for unit cells in which the first metal cell and the second metal cell had different shapes and the metal material of the first metal cell and the second metal cell were the same. Specifically, the first metal cell was a rectangular rod (solid structure) with a length Lax of 60 mm, a width of 20 mm, and a thickness of 3 mm. The second metal cell was a rectangular pipe (hollow structure) with a length Lbx of 60 mm, a width of 20 mm, and a height of 3 mm. The hollow portion of the second metal cell was a rectangular parallelepiped, with a width of 19 mm and a thickness of 2.5 mm, 2 mm, 1.5 mm, and 1.0 mm. Specifically, the thickness of the pair of side walls of the second metal cell was 0.5 mm, and the thicknesses t of the upper and lower walls were varied to 0.25 mm, 0.5 mm, 0.75 mm, and 1.0 mm. The material of the first metal cell and the second metal cell was aluminum (Al). As shown in Fig. 5, it can be seen that the mass ratio decreases when the thickness t of the upper wall and the lower wall is reduced. For reference, Fig. 5 also plots the shape of the second metal member cell when the thickness t of the upper wall and the lower wall is 1.5 mm, that is, when the second metal member cell is a rectangular bar (solid structure) with a length Lax of 60 mm, a width of 20 mm, and a thickness of 3 mm.

[0096] [Test Example 4] Next, the relationship between the stiffness ratio and the mass ratio was evaluated for unit cells in which the first metal cell and the second metal cell had different shapes and different metal materials. Specifically, the first metal cell was a rectangular rod (solid structure) with a length Lax of 60 mm, a width of 20 mm, and a thickness of 3 mm. The second metal cell was a rectangular pipe (hollow structure) with a length Lbx of 60 mm, a width of 20 mm, and a height of 3 mm, and had a hollow portion. The hollow portion of the second metal cell was a rectangular parallelepiped, with a width of 19 mm and a thickness of 2.5 mm, 2 mm, 1.5 mm, and 1.0 mm. Specifically, the thickness of the pair of side walls of the second metal cell was 0.5 mm, and the thicknesses t of the upper and lower walls were varied to 0.25 mm, 0.5 mm, 0.75 mm, and 1.0 mm. The materials used for the first and second metal cells were Steel / Al, Al / Mg, Ti / Al, Steel / Mg, Al / Al, Cu / Al, and Ti / Mg. As shown in Figure 6, as the thickness t of the upper and lower walls decreases toward 0.25 mm (as the thickness of the hollow portion increases), the rigidity ratio and mass ratio decrease (moving away from 1). It was also found that the rigidity ratio and mass ratio change when the shapes and materials of the first and second metal cells are combined. In particular, it was confirmed that the mass ratio decreases when dissimilar metals are combined, and the rigidity ratio increases with the Al / Cu combination. Combining dissimilar metals changes the Young's modulus and density, allowing for the rigidity ratio and mass ratio to be varied. In addition, in Figure 6, for reference, the shape of the second metal member cell is also plotted when the thickness t of the upper wall and lower wall is 1.5 mm, that is, when the second metal member cell is a flat square bar (solid structure) with a length Lax of 60 mm, a width of 20 mm, and a thickness of 3 mm.

[0097] [Study (Test Examples 1-4)] In Test Example 1, a dispersion curve was obtained, and a map was created showing the relationship between the band gap characteristics and the stiffness ratio and mass ratio, obtained by changing the stiffness ratio and mass ratio between the first metal cell and the second metal cell. From this map, it was confirmed that a vibration damping member with a wide first band gap bandwidth could be obtained when the stiffness ratio s was 0.8 to 10 and the mass ratio m was 0.1 to 0.2. It was also confirmed that a vibration damping member with a wide second band gap bandwidth could be obtained when the stiffness ratio s was 0.1 to 10 and the mass ratio m was 0.1 to 0.2. In Test Example 2, it was confirmed that a mass ratio m of approximately 0.3 could be achieved when the metal material of the first metal cell and the metal material of the second metal cell were combined using Cu / Al. In Test Example 3, it was confirmed that the mass ratio m could be reduced to approximately 0.2 when the second metal cell had a hollow structure and the thicknesses t of the upper and lower walls were 0.25 mm. In Test Example 4, when the metal materials of the first metal cell and the second metal cell were combined as Steel / Al, Ti / Al, Steel / Mg, Cu / Al, Ti / Mg, or Al / Mg, and the second metal cell was hollow and the thicknesses t of the upper and lower walls were within a predetermined small range, it was confirmed that the mass ratio m could be reduced to approximately 0.2 or even below 0.2. Furthermore, in Test Example 4, it was confirmed that by combining the metal materials of the first metal cell and the second metal cell with a hollow second metal cell, the mass ratio m could be varied within a range of 0.1 to 0.2 and the stiffness ratio could be varied within a range of 0.1 to 0.6. In this way, a dispersion curve could be obtained, and a map showing the relationship between the bandgap characteristics and parameters obtained by varying the parameters of the first metal cell and the second metal cell could be created. Furthermore, from this map, parameters that achieve desired bandgap characteristics could be identified. Furthermore, by making the internal structure of the first metal cell different from the internal structure of the second metal cell, or by making the metal material of the first metal cell different from the metal material of the second metal cell, it is possible to realize parameters that achieve the desired band gap characteristics.In this case, in each unit cell, the internal structure of the first metal cell is different from the internal structure of the second metal cell, and the metal material of the first metal cell is different from the metal material of the second metal cell, so that parameters that achieve the desired band gap characteristics can be realized.

[0098] [Test Example 5] Next, we investigated the bandgap characteristics as a function of the unit cell length Lcx. Specifically, the second metal cell had the characteristics s = 0.7 and m = 0.4, and the first metal cell length Lax and the second metal cell length Lbx were set to the same length. The imaginary dispersion curves were evaluated for six unit cells with Lcx = 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, and 180 mm. The results are shown in Figures 7 to 12. As shown in Figures 7 to 12, we confirmed that the bandgap frequency tends to shift toward lower frequencies as the unit cell length Lcx increases. This tendency is thought to correspond to the decrease in the natural frequency as the unit cell length increases. Furthermore, the bandgap wavelength and unit cell length considered here satisfy the Bragg condition nΛ = 2Lcx (n is a natural number, Λ is the wavelength, and Lcx is the unit cell length). Therefore, as the unit cell length Lcx increases, the wavelength Λ increases, which can be interpreted as the bandgap frequency decreasing. Also, similar to the results in Tables 1 to 8, the bandwidth tends to become smaller as the frequency becomes lower.

[0099] [Test Example 6] Next, we investigated the relationship between the ratio of the length Lax of the first metal cell to the length Lbx of the second metal cell and the band gap characteristics. Specifically, the characteristics of the second metal cell were set to s = 0.7 and m = 0.4, and the unit cell length Lcx = 100 mm. We evaluated the imaginary dispersion curves of nine unit cells with Lax:Lbx ratios of 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, and 1:9. The results are shown in Figures 13 to 21. As Figures 13 to 21 show, the two band gaps tend to shift toward lower frequencies as the ratio of the length Lax of the first metal cell increases. Furthermore, the two band gaps tend to shift toward higher frequencies as the ratio of the length Lbx of the second metal cell increases. This is thought to be because the characteristics of the second metal cell use values ​​of s = 0.7 and m = 0.4, where the stiffness ratio s is greater than the mass ratio m, and when the ratio of the length Lbx of the second metal cell increases, the decrease in stiffness of the entire unit cell is smaller than the decrease in mass.

[0100] Furthermore, the bandwidth becomes smaller as the proportion of either the first metal cell or the second metal cell becomes more one-sided. This is thought to be because the increase in the proportion of one phase leads to a more uniform unit cell. Furthermore, when Lax:Lbx = 9:1 and 1:9, the bandwidth is smaller. The former is a condition where the majority of the material is high in stiffness and density. On the other hand, the latter is a condition where the majority of the material is low in stiffness and density, but there are some areas where these are high. Therefore, the singularity (non-uniformity) of the unit cell is thought to be greater in the latter. Therefore, when Lax:Lbx = 9:1 and 1:9, the bandwidth is smaller in the former and larger in the latter.

[0101] Regarding the second band gap, when the ratio of the second metal cell was increased, the band width again increased when Lax:Lbx = 2:8. This is thought to be the result of the combination of two factors: the tendency for the band width to increase as the frequency increases, and the tendency for the band width to decrease as the ratio of one of the two increases.

[0102] [Test Example 7] A vibration suppression component containing a unit cell in which the formation of a band gap was confirmed was actually fabricated, and vibration tests were conducted to experimentally verify the response characteristics. Specifically, maraging steel was used, and first and second metal cells were formed using a powder bed method with a metal 3D printer (LASERTEC30SLM 2nd Generation, DMG Mori Seiki Co., Ltd.). The vibration suppression component was then fabricated by TIG welding the first and second metal cells alternately so that the total number of first and second metal cells was 3, 4, 6, 7, 8, or 10.

[0103] The first metal cell had Lax of 50.00 mm, Lay of 20.00 mm, and Laz of 3.00 mm. The second metal cell had Lbx of 50.00 mm, Lby of 20.00 mm, and Lbz of 3.00 mm. The first metal cell had a solid structure, while the second metal cell had a hollow rectangular cylindrical structure. The width of the hollow portion of the second metal cell was 16.97 mm (each side wall was 1.515 mm thick), and the height of the hollow portion of the second metal cell was 2.12 mm (top and bottom walls were 0.44 mm thick, respectively). Lcx was 100.00 mm, the stiffness ratio s was 0.7, and the mass ratio m was 0.4. The dispersion curve of the unit cell formed by joining the first and second metal cells was measured using WFEM, confirming a band gap at frequencies around 650 Hz to 800 Hz.

[0104] For the six vibration suppression components fabricated as described above, the excitation force and acceleration were measured through vibration tests, and the acceleration, which is the frequency response function (FRF) of the response acceleration to the excitation force, was calculated from the measurement data. As a result, it was found that there was no resonance peak in the frequency range of 650 Hz to 800 Hz obtained from the dispersion curve. This also confirmed the vibration suppression effect of forming a band gap in vibration suppression components containing unit cells. [Explanation of symbols]

[0105] 1 Vibration suppression member 10 unit cells 11 First Metal Cell 12 Second metal cell 15 Outer surface 100 Manufacturing system for vibration suppression components 113a Dispersion curve acquisition part 113b Parameter specification part X first direction Z thickness direction

Claims

1. a plurality of unit cells including a first metal cell and a second metal cell, the first metal cell and the second metal cell being connected in a first direction perpendicular to the thickness direction; the plurality of unit cells are connected in the first direction, so that the first metal cells and the second metal cells are arranged alternately; the plurality of unit cells have smooth outer surfaces at the outermost positions in the thickness direction; A vibration suppression member in which, in each of the unit cells, the rigidity of the first metal cell is different from the rigidity of the second metal cell, the mass per unit length in the first direction of the first metal cell is different from the mass per unit length in the first direction of the second metal cell, or the rigidity of the first metal cell is different from the rigidity of the second metal cell and the mass per unit length in the first direction of the first metal cell is different.

2. The vibration suppressing member according to claim 1 , wherein in each of the unit cells, the first metal cell and the second metal cell have different internal structures.

3. the first metal cell is a solid structure; The vibration suppressing member according to claim 2 , wherein the second metal cell has a hollow structure.

4. 3. The vibration suppression member of claim 2, wherein the second metal cell has at least one structure selected from the group consisting of an E-shaped structure, an H-shaped structure, an I-shaped structure, an M-shaped structure, an N-shaped structure, a U-shaped structure, a Z-shaped structure, a cylindrical structure, a harmonica structure, a truss structure, a honeycomb structure, a lattice structure, a mesh structure, and a porous structure.

5. The vibration suppressing member according to claim 1 , wherein in each of the unit cells, the metal material of the first metal cell is different from the metal material of the second metal cell.

6. 2. The vibration suppression member of claim 1, wherein in each of the unit cells, the internal structure of the first metal cell is different from the internal structure of the second metal cell, and the metal material of the first metal cell is different from the metal material of the second metal cell.

7. the first metal cell is made of steel; the second metal cell is made of an aluminum alloy; the first metal cell is a solid structure; The second metal cell has a hollow structure. The vibration suppressing member according to claim 6 .

8. When a ratio of the rigidity of the second metal cell to the rigidity of the first metal cell is defined as a rigidity ratio s, and a ratio of a mass of the second metal cell per unit length in the first direction to a mass of the first metal cell per unit length in the first direction is defined as a mass ratio m, 2. The vibration suppressing member according to claim 1, which satisfies the requirements of 0.01≦s / m<1 and 1<s / m≦100.

9. When a ratio of the rigidity of the second metal cell to the rigidity of the first metal cell is defined as a rigidity ratio s, and a ratio of a mass of the second metal cell per unit length in the first direction to a mass of the first metal cell per unit length in the first direction is defined as a mass ratio m, The vibration suppressing member according to claim 1 , which satisfies the requirement of 2≦s / m≦100.

10. When a ratio of the rigidity of the second metal cell to the rigidity of the first metal cell is defined as a rigidity ratio s, and a ratio of a mass of the second metal cell per unit length in the first direction to a mass of the first metal cell per unit length in the first direction is defined as a mass ratio m, 2. The vibration suppressing member according to claim 1, which satisfies the requirements of 0.01≦s≦100 and 0.01≦m≦100 (excluding 0.8<s<1 / 0.9 and 0.9<m<1 / 0.9).

11. When a ratio of the rigidity of the second metal cell to the rigidity of the first metal cell is defined as a rigidity ratio s, and a ratio of a mass of the second metal cell per unit length in the first direction to a mass of the first metal cell per unit length in the first direction is defined as a mass ratio m, 2. The vibration suppressing member according to claim 1, which satisfies the requirements of 0.01≦s≦100 and 0.01≦m≦0.

2.

12. When a ratio of the rigidity of the second metal cell to the rigidity of the first metal cell is defined as a rigidity ratio s, and a ratio of a mass of the second metal cell per unit length in the first direction to a mass of the first metal cell per unit length in the first direction is defined as a mass ratio m, 2. The vibration suppressing member according to claim 1, which satisfies the requirements of 5≦s≦100 and 0.01<m≦100.

13. When a ratio of the rigidity of the second metal cell to the rigidity of the first metal cell is defined as a rigidity ratio s, and a ratio of a mass of the second metal cell per unit length in the first direction to a mass of the first metal cell per unit length in the first direction is defined as a mass ratio m, 2. The vibration suppressing member according to claim 1, which satisfies the requirements of 0.6≦s≦100 and 0.01≦m≦0.

3.

14. When a ratio of the rigidity of the second metal cell to the rigidity of the first metal cell is defined as a rigidity ratio s, and a ratio of a mass of the second metal cell per unit length in the first direction to a mass of the first metal cell per unit length in the first direction is defined as a mass ratio m, 2. The vibration suppressing member according to claim 1, which satisfies the requirements of 0.8≦s≦100 and 0.01≦m≦0.

2.

15. When the rigidity of the first metal cell is s1 and the rigidity of the second metal cell is s2, s1>s2; where m1 is a mass of the first metal cell per unit length in the first direction and m2 is a mass of the second metal cell per unit length in the first direction, m1>m2; The vibration suppression member according to claim 1 , wherein a ratio of a length of the first metal cells in the first direction to a length of the second metal cells in the first direction is 1 / 9 or more and 8 / 2 or less.

16. The vibration suppressing member according to claim 1 , wherein the length of the unit cell in the first direction is 10 mm or more and 100 mm or less.

17. A method for manufacturing a vibration suppression member, The vibration suppressing member is a plurality of unit cells including a first metal cell and a second metal cell, the first metal cell and the second metal cell being connected in a first direction perpendicular to the thickness direction; the plurality of unit cells are connected in the first direction, so that the first metal cells and the second metal cells are arranged alternately; the plurality of unit cells have smooth outer surfaces at the outermost positions in the thickness direction; In each of the unit cells, the rigidity of the first metal cell and the rigidity of the second metal cell are different, or the mass per unit length in the first direction of the first metal cell and the mass per unit length in the first direction of the second metal cell are different, or the rigidity of the first metal cell and the rigidity of the second metal cell are different and the mass per unit length in the first direction of the first metal cell and the mass per unit length in the first direction of the second metal cell are different, The method for manufacturing the vibration damping member includes: a dispersion curve acquisition step of acquiring a dispersion curve representing a relationship between the frequency and wave number of the vibration suppression member; identifying parameters of the first metal cell, the second metal cell, and the unit cell, which satisfy a bandgap characteristic representing a frequency of the bandgap derived from the dispersion curve, the parameters including at least one selected from the group consisting of Young's modulus, density, length, cross-sectional shape, stiffness ratio, and mass ratio; A method for manufacturing a vibration suppression member, comprising:

18. The method for manufacturing a vibration damping member according to claim 17 , wherein the identifying step identifies the parameter from a map that represents the relationship between the band gap characteristics obtained by changing the parameter in the dispersion curve and the parameter.

19. 19. The method for manufacturing a vibration damping member according to claim 18, wherein the specifying step specifies the stiffness ratio and the mass ratio from a map that represents the relationship between the band gap characteristics obtained by changing the stiffness ratio and the mass ratio in the dispersion curve and the stiffness ratio and the mass ratio.

20. 19. The method for manufacturing a vibration damping member according to claim 18, wherein the specifying step specifies the length of the unit cell in the first direction from a map that represents the relationship between the band gap characteristics obtained by changing the length of the unit cell in the first direction in the dispersion curve and the length of the unit cell in the first direction.

21. 19. A method for manufacturing a vibration damping member as described in claim 18, wherein the identification step identifies the lengths of the first metal cell and the second metal cell in the first direction from a map showing the relationship between the band gap characteristics obtained by changing the lengths of the first metal cell and the second metal cell in the first direction in the dispersion curve and the lengths of the first metal cell and the second metal cell in the first direction.

22. A manufacturing system for a vibration damping member, comprising: The vibration suppressing member is a plurality of unit cells including a first metal cell and a second metal cell, the first metal cell and the second metal cell being connected in a first direction perpendicular to the thickness direction; the plurality of unit cells are connected in the first direction, so that the first metal cells and the second metal cells are arranged alternately; the plurality of unit cells have smooth outer surfaces at the outermost positions in the thickness direction; In each of the unit cells, the rigidity of the first metal cell and the rigidity of the second metal cell are different, or the mass per unit length in the first direction of the first metal cell and the mass per unit length in the first direction of the second metal cell are different, or the rigidity of the first metal cell and the rigidity of the second metal cell are different and the mass per unit length in the first direction of the first metal cell and the mass per unit length in the first direction of the second metal cell are different, The manufacturing system for the vibration damping member includes: a dispersion curve acquisition unit that acquires a dispersion curve that represents a relationship between the frequency and wave number of the vibration suppression member; a parameter specifying unit that specifies parameters including at least one selected from the group consisting of Young's modulus, density, length, cross-sectional shape, stiffness ratio, and mass ratio of the first metal cell, the second metal cell, and the unit cell, which satisfy bandgap characteristics that represent the frequency of the bandgap derived from the dispersion curve; and A manufacturing system for a vibration suppression member, comprising:

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