A lattice cylindrical shell superstructure with broadband vibration isolation characteristics and its fabrication method

Abstract

This invention discloses a lattice cylindrical shell superstructure with broadband vibration isolation characteristics and its fabrication method, belonging to the field of vibration control, which can integrate the load-bearing and vibration isolation functions of curved shell structures. The lattice cylindrical shell superstructure of this invention is composed of lattice structural cells containing local resonant structural units arranged circumferentially and axially. Each lattice structural cell is composed of an outer frame and internal double-pyramid crossbars, hexahedral blocks, and metal cylinders forming local resonant structural units. These lattice structural cells create a bandgap in the lattice cylindrical shell structure to attenuate elastic waves. Through bandgap design, broadband vibration suppression can be achieved when the lattice cylindrical shell structure is subjected to vibration excitation. Furthermore, the rod-based lattice structure is lightweight, high-strength, and designable, giving the overall cylindrical shell structure both superior static load-bearing performance and vibration suppression capabilities.

Description

Technical Field

[0001] This invention belongs to the field of vibration control technology, specifically relating to a lattice cylindrical shell superstructure with broadband vibration isolation characteristics and its preparation method. Background Technology

[0002] Lattice cylindrical shell structures, due to their lightweight, high strength, and high design flexibility, have broad application prospects in aerospace and shipbuilding engineering. Currently, most research on lattice cylindrical shell structures focuses on static performance, specifically achieving lightweighting through structural or material design while ensuring static load-bearing capacity, thereby achieving energy conservation and emission reduction. In recent years, with the development of manufacturing processes, especially additive manufacturing technology (3D printing), the functionalization of structures has become easier to achieve, and the demand is increasing. While lattice-designed cylindrical shell structures offer lightweighting, lightweight structures are more sensitive to vibration, making the suppression of harmful vibrations particularly important.

[0003] Locally resonant acoustic metamaterials, due to the presence of resonant units, can suppress low-frequency elastic waves, making them a novel material for vibration control. Their structural composition typically involves periodically embedding functional microstructural units with resonant characteristics within an elastic matrix. When an elastic wave is incident on the metamaterial, if the incident frequency is close to the resonant frequency of the resonant microstructural unit, the elastic wave energy will be consumed by the resonant unit, thus suppressing the propagation of the elastic wave near that frequency. Furthermore, due to the periodicity of the resonant unit, the elastic wave attenuation exhibits a bandgap characteristic. The design method of locally resonant acoustic metamaterials provides a new approach to vibration suppression in engineering structures. Applying this method to the design of lattice shell structures holds promise for achieving integrated load-bearing and vibration isolation in these structures. However, there is currently no research on the application of locally resonant metamaterials in rod-type lattice shell structures. Summary of the Invention

[0004] This invention provides a lattice cylindrical shell superstructure with broadband vibration isolation characteristics and its preparation method. In addition to the high load-bearing capacity of the lattice structure, the cylindrical shell structure has the function of broadband vibration suppression by introducing local resonance units.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A lattice cylindrical shell superstructure with broadband vibration isolation characteristics is composed of lattice structural cells containing local resonant structural units arranged in a circumferential and axial array; the lattice structural cells include: an outer frame and local resonant structural units composed of internal double pyramid cross rods, hexahedral blocks, and metal cylinders.

[0007] In the structure described above, both the outer frame and the inner double pyramid cross rods are round rods, and the inner cross rods are connected to the outer frame through nodes;

[0008] The circumferential curvature of the hexahedral block is the same as that of the lattice cylindrical shell superstructure, and the hexahedral block is located at the node of the internal double pyramid cross rod.

[0009] The hexahedral block is provided with a reserved cylindrical hole, the central axis of which points to and is perpendicular to the central axis of the lattice cylindrical shell superstructure;

[0010] The diameter of the metal cylinder is the same as the diameter of the reserved cylindrical hole. The metal cylinder is embedded in the reserved cylindrical hole, and the metal cylinder is symmetrical about the center point of the hexahedral block.

[0011] The external frame, the internal double pyramid crossbars, and the hexahedral blocks all have the same material properties.

[0012] Beneficial effects: This invention provides a lattice cylindrical shell superstructure with broadband vibration isolation characteristics and its fabrication method. Compared with the prior art, this invention has the following advantages:

[0013] 1. The lattice shell superstructure of the present invention is composed of lattice structural cells containing local resonant structural units arranged in a circumferential and axial array. The lattice structural cells are composed of an outer frame and internal double pyramidal crossbars, hexahedral blocks, and metal cylinders forming local resonant structural units. The lattice structural cells give the lattice shell structure a band gap that attenuates elastic waves. Through the band gap design, the lattice shell structure can achieve broadband vibration suppression when subjected to vibration excitation. When the shell structure is subjected to axial and lateral vibration excitation, due to the presence of the resonant units, the elastic waves generated by the vibration excitation are attenuated in certain specific frequency bands, achieving effective vibration isolation.

[0014] 2. The structural parameters (diameter, length, etc.) of the internal double pyramid cross rod, hexahedral block, and metal cylinder in this invention can be changed to adjust the frequency range (band gap) of vibration attenuation. Reducing the diameter of the internal double pyramid cross rod will lower the lower boundary frequency of the band gap. When the parameters of the hexahedral block and metal cylinder are changed to increase the mass, the lower boundary frequency range of the band gap will decrease. Therefore, the band gap can be customized as needed by changing the parameters.

[0015] 3. The lower boundary of the bandgap of the cylindrical shell superstructure in this invention is affected by the local resonant unit, and the upper boundary is affected by the external frame, and the bandgap has broadband characteristics;

[0016] 4. Compared with traditional acoustic metamaterials, this invention uses a lattice structure as the matrix and embeds the oscillator periodically into the lattice matrix to form a cylindrical shell structure. The rod lattice structure has the characteristics of being lightweight, high-strength, and designable, so that the overall cylindrical shell structure has both superior static load-bearing performance and vibration suppression function, and can achieve the integration of load bearing and vibration isolation.

[0017] 5. The lattice matrix of the lattice cylindrical shell superstructure in this invention can be prepared using 3D printing technology. The metal cylinder is manually embedded into a hexahedral block with pre-drilled holes, which is easy to manufacture. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the lattice cylindrical shell superstructure with broadband vibration isolation characteristics in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the external framework of the lattice structure cell in an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the resonator inside the lattice structure cell in an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the lattice structure cell in an embodiment of the present invention;

[0022] Figure 5 This is a graph showing the correlation between transmission loss and frequency obtained from simulation calculations and experimental tests in this embodiment of the invention.

[0023] In the diagram, 1-external frame, 2-internal double pyramid crossbar, 3-hexahedral block, 4-metal cylinder. Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments:

[0025] like Figure 1-4 As shown, a lattice cylindrical shell superstructure with broadband vibration isolation characteristics is composed of lattice structural cells containing localized resonant structural units arranged in an array along the circumferential and axial directions, such as... Figure 2 As shown, the lattice structure cell consists of an outer frame 1, an inner double-pyramid crossbar 2, a hexahedral block 3, and a metal cylinder 4. The outer frame 1 and the inner double-pyramid crossbar 2 are both round rods, and the inner double-pyramid crossbar 2 is connected to the outer frame 1 through nodes. The circumferential curvature of the hexahedral block 3 is the same as the curvature of the lattice shell, and the hexahedral block 3 is located at the intersection of the rods of the inner double-pyramid crossbar 2. The hexahedral block 3 has a reserved cylindrical hole, and the central axis of the reserved cylindrical hole points to and is perpendicular to the central axis of the lattice shell. The diameter of the metal cylinder 4 is the same as the diameter of the reserved cylindrical hole of the hexahedral block 3. The metal cylinder 4 is embedded in the reserved cylindrical hole, and the metal cylinder 4 is symmetrical about the center point of the hexahedral block 3.

[0026] The following defines the dimensions and material parameters of the lattice structure cell: the outer frame rod has a diameter of 3 mm, a height of 20 mm, a width of 20 mm, and a circumferential curvature of 12°; the inner double-pyramid cross rod has a diameter of 2 mm; the hexahedral block has a thickness of 10 mm, a height of 15 mm, a circumferential curvature of 10°, and a pre-drilled hole diameter of 10 mm; the metal cylinder has a diameter of 10 mm and a height of 18 mm. The outer frame, the inner double-pyramid cross rod, and the hexahedral block are all made of photosensitive resin with a Young's modulus of 2600 MPa, a Poisson's ratio of 0.4, and a density of 1150 Kg / m³. 3 The metal cylinder is made of steel, with a Young's modulus of 206 GPa, a Poisson's ratio of 0.3, and a density of 7850 kg / m³. 3 .

[0027] The aforementioned lattice cylindrical shell superstructure with broadband vibration isolation characteristics is assembled according to the following steps:

[0028] 1. Use Solidworks modeling software to create an integrated model of the external frame, internal double pyramid crossbars, and hexahedral blocks;

[0029] 2. The above-mentioned structural model was prepared using 3D printing technology;

[0030] 3. Embed the metal cylinder into the reserved hole of the hexahedral block, and use AB glue to bond and fix the metal cylinder to the reserved hole;

[0031] 4. Wait for the AB glue to cure, and the fabrication of the lattice shell superstructure is complete.

[0032] A lattice cylindrical superstructure with 30 cells circumferentially and 10 cells vertically ( Figure 1 Taking a lattice cylindrical shell superstructure as an example, the vibration transmissibility was tested using a frequency sweep test. The specific test process is as follows:

[0033] 1. The structure is freely suspended using elastic ropes to simulate a free boundary; 2. A vibration excitation system is used to provide a sinusoidal vibration input signal; 3. An accelerometer is used to receive the input and output signals; 4. A data acquisition instrument is used to collect the input and output data; 5. The collected data is processed to obtain the vibration transmission curve of the structure.

[0034] The experimental test frequency range was 0–6000 Hz, with a sampling frequency interval of 10 Hz; the vibration transfer function expression used in the calculation was as follows. The vibration transfer curves obtained from the experiment and simulation are shown below. Figure 5As shown by the solid and dashed lines, the experimentally measured vibration attenuation frequency range agrees well with the simulation results. Within the frequency range of 1786 Hz to 5600 Hz (shaded area in the figure), the vibration transmissibility decreases significantly, indicating that the vibration is effectively attenuated in this frequency band. This proves the effectiveness of using this lattice shell superstructure to achieve broadband vibration isolation. Analysis revealed that the vibration mode corresponding to the lower boundary of the vibration attenuation band gap is the local resonance of the internal resonant unit, while the vibration mode corresponding to the upper boundary of the vibration attenuation is the vibration of the external frame. Therefore, the appearance of the vibration attenuation frequency band is related to the local resonance of the resonator and the vibration of the external frame rods.

[0035] The above are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A lattice cylindrical shell superstructure with broadband vibration isolation characteristics, characterized in that, The lattice shell superstructure is composed of lattice structural cells containing local resonant structural units arranged circumferentially and axially. Each lattice structural cell includes an outer frame and local resonant structural units composed of internal double-pyramid crossbars, hexahedral blocks, and metal cylinders. The internal double-pyramid crossbars are connected to the outer frame via nodes. The hexahedral blocks are located at the intersections of the internal double-pyramid crossbars. The metal cylinders are embedded in the hexahedral blocks, making the metal cylinders symmetrical about the center of the hexahedral blocks. The circumferential curvature of the hexahedral blocks is the same as the curvature of the lattice shell superstructure. The hexahedral blocks have pre-drilled cylindrical holes, into which the metal cylinders are embedded. The central axis of the pre-drilled cylindrical holes points towards and is perpendicular to the central axis of the lattice shell superstructure. The frequency range of vibration attenuation can be adjusted by changing the structural parameters of the outer frame rods, internal double-pyramid crossbars, hexahedral blocks, and metal cylinders.

2. The lattice cylindrical shell superstructure with broadband vibration isolation characteristics according to claim 1, characterized in that, Both the outer frame and the internal double pyramid crossbars are round rods.

3. The lattice cylindrical shell superstructure with broadband vibration isolation characteristics according to claim 1, characterized in that, The diameter of the metal cylinder is the same as the diameter of the reserved cylindrical hole in the hexahedral block.

4. The lattice cylindrical shell superstructure with broadband vibration isolation characteristics according to claim 1, characterized in that, The external frame, the internal double pyramid crossbars, and the hexahedral blocks all have the same material properties.

5. The method for preparing the lattice cylindrical shell superstructure with broadband vibration isolation characteristics according to any one of claims 1-4, characterized in that, Includes the following steps: S1: Use Solidworks modeling software to create an integrated model of the external frame, internal double pyramid crossbars, and hexahedral blocks; S2: The above structural model was prepared using 3D printing technology; S3: Embed the metal cylinder into the reserved hole of the hexahedral block, and use AB glue to bond and fix the metal cylinder to the reserved hole; S4: Wait for the AB glue to cure, and complete the preparation of the lattice shell superstructure.

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