A three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption properties

Abstract

A three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption characteristics includes a cubic shell with three through holes, a central cylinder passing through the through hole of the three-dimensional shell coaxially and pointing to the center of the cubic shell, a base surface of the central cylinder parallel to the outer surface of the three-dimensional shell, and a side surface of the central cylinder connected to the inner wall of the cubic shell through a fan-shaped block structure, and the three-dimensional shell, the fan-shaped block structure and the central cylinder are made of three different materials. The invention is lighter in weight with the same size, and can produce low-frequency bandgap characteristics, and has a controllable bandgap range for seismic waves. The bandgap can be adjusted by adjusting the number of fan-shaped blocks, the height of the central cylinder, the fan-shaped angle of the fan-shaped blocks and the wall thickness of the cubic shell. Compared with Bragg scattering type seismic metamaterials, it has the advantages of easy layout and material saving. The invention can be used for filling building foundations and effectively reducing shocks for important building infrastructure.

Description

Technical Field

[0001] The invention belongs to the technical field of earthquake damping, and in particular relates to a three-dimensional face-centered cubic earthquake metamaterial with low-frequency damping characteristics. Background Art

[0002] Earthquake is a serious natural disaster. With its suddenness and extremely destructiveness, it seriously threatens people’s lives and property. Therefore, earthquake protection is particularly important.

[0003] Elastic metamaterials are dielectric materials with periodic structures. They have attracted extensive attention from scholars because they can suppress the propagation of seismic waves within a certain range. In recent years, people have begun to develop elastic metamaterials from the field of solid physics to the field of earthquake engineering, resulting in a new shock absorption technology, namely seismic metamaterials.

[0004] Most of the existing seismic metamaterials are two-dimensional structures, and the main layout form is periodic layout protection. Due to the limitations of their structure, they can only absorb surface seismic waves, and fail to fully shield seismic waves in all directions. Recent research on the three-dimensional structure of seismic metamaterials is also mostly focused on simple cubic structures. Because their structures are filled with solid materials and the existing structures are large in size, they are often concentrated within a few meters or even tens of meters to achieve the required vibration reduction frequency (0-40Hz) of their buildings. Therefore, the existing structures generally require a large amount of materials during construction, which increases their construction costs. At the same time, due to their large size and structure, there are many inconveniences during installation and transportation. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption characteristics, which has a small size, good processing and transportation conditions and excellent low-frequency shock absorption performance.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption characteristics, whose main body is a cubic shell 1, characterized in that each set of opposite faces of the cubic shell 1 is provided with a through hole penetrating the center of the cube, and a central cylinder 3 is respectively arranged at both ends of each through hole, each central cylinder 3 is coaxial with the through hole in which it is located, and the inner end is spaced apart from the center of the cube, and the side surface of each central cylinder 3 is connected to the inner wall of the through hole through a plurality of fan-shaped block structures 2, and the cubic shell 1, the fan-shaped block structure 2 and the central cylinder 3 form a face-centered cubic structure as a whole.

[0008] The parameters of the through holes are completely the same, the parameters of the central cylinders 3 are completely the same, and the structures, parameters and settings of the sector-shaped block structures 2 connected to the central cylinders 3 are completely the same.

[0009] The central cylinders 3 are arranged in the six central through holes of the cubic shell 1, and there is no connection between the central cylinders 3, which are independent of each other. The end base surface of each central cylinder 3 is parallel to an outer surface of the cubic shell 1, and the outer end of each central cylinder 3 is flush with an outer surface of the cubic shell 1, and the longitudinal section of each sector block structure 2 is parallel to an outer surface of the cubic shell 1.

[0010] Each cross section of the cubic shell 1 is a square with a hole in the center, and the fan-shaped block structures 2 are cross-distributed and connected to the inner wall of the through hole and the outer wall of the central cylinder 3 respectively.

[0011] The transverse cross-section of the sector block structure 2 is a sector cut out by a circular ring, the outer diameter of the circular ring is the same as the aperture of the through hole, and the inner diameter of the circular ring is the same as the outer diameter of the central cylinder 3; the longitudinal cross-section shapes of the sector block structures 2 are the same, the transverse distance between the cross-sections on both sides is 10 mm, and the longitudinal height of the sector block structure 2 is the same as the thin-wall thickness of the cubic shell 1.

[0012] The fan-shaped block structure 2 is circumscribed to the through hole of the cubic shell 1 and inscribed to the central cylinder 3. The fan-shaped block structure 2 is embedded in the cubic shell 1. The cross sections on both sides of the fan-shaped block structure 2 are parallel to the inner and outer thin-wall surfaces of the cubic shell 1. The cross section on one side of the fan-shaped block structure 2 is also parallel to the end base surface of the central cylinder 3.

[0013] The cubic shell 1 is a thin shell structure, and through holes perpendicular to the surface are provided on the surface of the thin shell structure. The cubic shell 1 has a side length of 100 mm, a wall thickness of 5 mm, and a through hole diameter of 80 mm.

[0014] The longitudinal height of the central cylinder 3 is greater than the longitudinal height of the sector block structure 2 and the thin wall thickness of the cubic shell 1 , and the longitudinal height of the central cylinder 3 is 4 times the longitudinal height of the sector block structure 2 and the thin wall thickness of the cubic shell 1 .

[0015] The radius of the through hole is 1.6 times the radius of the central cylinder 3 .

[0016] The cubic shell 1 , the sector block structure 2 and the central cylinder 3 are made of different materials respectively.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] Compared with the prior art, the three-dimensional face-centered cubic seismic metamaterial of the present invention has a lighter mass than the traditional seismic metamaterial with the same size, and can produce low-frequency bandgap characteristics, and has a controllable bandgap range for seismic waves. Its bandgap can be adjusted by adjusting the number of fan-shaped blocks, the height of the central cylinder, the fan-shaped angle of the fan-shaped blocks, and the wall thickness of the cubic shell. Compared with the Bragg scattering type seismic metamaterial, it has the advantages of easy layout and material saving. The present invention can be used for building foundation filling and effective shock absorption protection for important building infrastructure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of a unit cell of a three-dimensional face-centered cubic seismic metamaterial according to the present invention.

[0020] Figure 2 This is the energy band diagram of the unit cell of the three-dimensional face-centered cubic seismic metamaterial of the present invention.

[0021] Figure 3 This is a structural diagram of the three-dimensional face-centered cubic seismic metamaterial of the present invention.

[0022] Figure 4 It is a diagram of the foundation filling structure of the three-dimensional face-centered cubic seismic metamaterial of the present invention.

[0023] Figure 5 It is a frequency response function curve diagram of the three-dimensional face-centered cubic seismic metamaterial of the present invention. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0025] like Figure 1 As shown, a new type of three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption characteristics includes a cubic shell 1, each set of opposite faces of the cubic shell 1 has a through hole at the center, three sets of opposite faces have three through holes in total, and each through hole runs through the center of the cube. A central cylinder 3 is respectively arranged at both ends of each through hole, and a total of six central cylinders 3 are arranged in the three through holes. Each central cylinder 3 is coaxial with the through hole in which it is located, and the inner end points to the body center of the cubic shell 1 and has a certain distance from the body center, that is, there is a certain distance between the two central cylinders 3 in the same through hole. The end base surface of the central cylinder 3 is parallel to an outer surface of the cubic shell 1, and the side of the central cylinder 3 is connected to the inner wall of the through hole through a fan-shaped block structure 2. The cubic shell 1, the fan-shaped block structure 2 and the central cylinder 3 are respectively made of three different materials.

[0026] In this embodiment, the cross section of the cubic shell 1 is a square with a hole in the center, and the sector block structures 2 are cross-distributed and connected to the inner wall of the through hole and the outer wall of the central cylinder 3 respectively.

[0027] Specifically, the central cylinder 3 is perpendicular to the outer surface of the cubic shell 1 and is coaxially arranged with the through hole. The central cylinders 3 are not connected to each other. The central cylinder 3 is connected to the sector block structure 2 and the cross section of the central cylinder is circular.

[0028] In the present invention, the longitudinal height of the central cylinder 3 is greater than the longitudinal height of the sector block structure 2 and the thin-wall thickness of the cubic shell 1 , and the longitudinal height 2 of the sector block structure 2 is equal to the thin-wall thickness of the cubic shell 1 .

[0029] In the embodiment of the present invention, the radius of the central cylinder 3 is 25 mm, the longitudinal height is 20 mm, the side length of the cubic shell 1 is 100 mm, the through hole radius of the cubic shell 1 is 40 mm, the thin wall thickness is 5 mm, the outer radius of the fan-shaped block structure 2 is 40 mm, the inner radius is 25 mm, the longitudinal height is 5 mm, the lateral distance between the two sides is 10 mm, and the angle θ between the two adjacent fan-shaped block structures 2 is 90°

[0030] The cubic shell 1, the sector block structure 2 and the central cylinder 3 of the present invention are made of epoxy resin, silicone rubber and lead respectively. The specific material parameters are: epoxy resin, density ρ1 = 1180 kg / m 3 , shear modulus E1 = 4.35 × 10 9 Pa, Poisson's ratio μ1 = 0.368; Silicone rubber, density ρ2 = 1300 kg / m 3 , shear modulus E2 = 1.175 × 10 5 Pa, Poisson's ratio μ2 = 0.469; lead, density ρ3 = 11600 kg / m 3 , shear modulus E3 = 4.08 × 10 10 Pa, Poisson's ratio μ3 = 0.369. Figure 2 It can be seen that there are band gaps in the 0-40Hz range, where the first band gap is 4.463-5.019Hz and the second band gap is 7.9-30.1Hz.

[0031] The three-dimensional face-centered cubic seismic metamaterial structure of the present invention is obtained by extending the three-dimensional face-centered cubic seismic metamaterial unit cell in three mutually perpendicular directions in space, such as Figure 3 shown.

[0032] In actual use, the three-dimensional face-centered cubic seismic metamaterial structure of the present invention is often coated with a cement layer of a certain thickness so that it can adapt to various complex environments. The thickness of the cement layer in the present invention is 50 mm, and the selected material parameters are density ρ4 = 2300 kg / m 3 , shear modulus E4 = 4 × 10 10 Pa, Poisson's ratio μ4 = 0.2. Figure 4 shown.

[0033] refer to Figure 5 , Figure 5 This is the transmission spectrum of a periodic structure consisting of a 4X4X4 unit cell space extension and a cement layer wrapped around it. It can be seen that there is a region in the frequency domain where the vibration attenuation is less than 0dB, which corresponds to the low-frequency band gap in the band structure. It should be noted that in the simulation of the transmission characteristics, the S-wave excitation method was adopted. Figure 5 It can be seen that the transmission spectrum corresponds to the complete band gap in the band structure.

[0034] It can be seen that the three-dimensional face-centered cubic seismic metamaterial structure of the present invention can enable the three-dimensional structure to generate a low-frequency band gap and effectively control seismic waves.

[0035] The three-dimensional face-centered cubic seismic metamaterial of the present invention has a lighter mass than the traditional three-dimensional phononic crystal structure under the condition of the same size, and can produce low-frequency band gap characteristics, and has a controllable band gap range for seismic waves. Its band gap can be adjusted by adjusting the number of fan-shaped blocks, the height of the central cylinder, the fan-shaped angle of the fan-shaped blocks, and the wall thickness of the cubic shell. Compared with the Bragg scattering type seismic metamaterial, it has the advantages of easy layout and material saving. The present invention can be used for building foundation filling and effective shock absorption protection for important building infrastructure.

Claims

1. A three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption characteristics, wherein the main body is a cubic shell (1), characterized in that: Each set of opposite faces of the cubic shell (1) is provided with a through hole penetrating the center of the cube, and a central cylinder (3) is provided at each end of each through hole. Each central cylinder (3) is coaxial with the through hole in which it is located, and the inner end is spaced apart from the center of the cube. The side surface of each central cylinder (3) is connected to the inner wall of the through hole via a plurality of fan-shaped block structures (2). The cubic shell (1), the fan-shaped block structure (2) and the central cylinder (3) form a face-centered cubic structure as a whole. Each cross section of the cubic shell (1) is a square with a hole in the center, and the fan-shaped block structures (2) are cross-distributed and respectively connected to the inner wall of the through hole and the outer wall of the central cylinder (3); The cubic shell (1), the sector block structure (2) and the central cylinder (3) are respectively made of different materials.

2. The three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption characteristics according to claim 1, characterized in that: The parameters of each through hole are completely the same, the parameters of each central cylinder (3) are completely the same, and the structure, parameters and setting form of the fan-shaped block structure (2) connected to each central cylinder (3) are completely the same.

3. The three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption characteristics according to claim 1, characterized in that: The central cylinders (3) are arranged in the six central through holes of the cubic shell (1), and the central cylinders (3) are not connected to each other and are independent of each other. The end base surface of each central cylinder (3) is parallel to an outer surface of the cubic shell (1), the outer end of each central cylinder (3) is flush with an outer surface of the cubic shell (1), and the longitudinal section of each sector block structure (2) is parallel to an outer surface of the cubic shell (1).

4. The three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption characteristics according to claim 1, characterized in that: The fan-shaped block structure (2) is circumscribed to the through hole of the cubic shell (1) and is inscribed to the central cylinder (3). The fan-shaped block structure (2) is embedded in the cubic shell (1). The cross sections on both sides of the fan-shaped block structure (2) are parallel to the inner and outer thin-wall surfaces of the cubic shell (1). The cross section on one side of the fan-shaped block structure (2) is also parallel to the end base surface of the central cylinder (3).

5. The three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption characteristics according to claim 1, characterized in that: The cubic shell (1) is a thin shell structure, and through holes perpendicular to the surface are provided on the surface of the thin shell structure. The cubic shell (1) has a side length of 100 mm, a wall thickness of 5 mm, and a through hole diameter of 80 mm.

6. The three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption characteristics according to claim 1, characterized in that: The longitudinal height of the central cylinder (3) is greater than the longitudinal height of the sector block structure (2) and the thin wall thickness of the cubic shell (1); the longitudinal height of the central cylinder (3) is 4 times the longitudinal height of the sector block structure (2) and the thin wall thickness of the cubic shell (1).

7. The three-dimensional face-centered cubic seismic metamaterial with low-frequency shock absorption characteristics according to claim 1, characterized in that: The radius of the through hole is 1.6 times the radius of the central cylinder (3).

Images