Body-centered cubic sandwich superstructure with low-frequency broadband characteristic and working method thereof

Abstract

The invention relates to a body-centered cubic sandwich superstructure with low-frequency broadband characteristics and a working method thereof.The body-centered cubic sandwich superstructure comprises a plurality of unit cell structures periodically arranged in the X direction and the Y direction, and each unit cell structure comprises an upper panel, an internal truss structure and a lower panel which are sequentially arranged from top to bottom; the body center of the internal truss structure is provided with a spiral beam-mass block local resonance unit, the spiral beam-mass block local resonance unit comprises at least one Archimedes spiral beam and a mass block, one end of the Archimedes spiral beam is fixed with the mass block, and the other end of the Archimedes spiral beam is fixed with a body center node of the internal truss structure. According to the invention, the structure is simple, the structural integration level is high, and through the ingenious built-in design, the Archimedes spiral beam oscillator unit is embedded into the body-centered cubic sandwich frame, and a significant bending wave band gap can be generated in a low-frequency band by using a multi-mode local resonance mechanism without damaging the surface of a panel.

Description

Technical Field

[0001] This invention relates to a body-centered cubic sandwich superstructure with low-frequency broadband characteristics and its working method. Background Technology

[0002] With the continuous pursuit of lightweight and high performance in fields such as aerospace, high-speed vehicles, and precision instruments, lattice sandwich structures are highly favored due to their excellent high specific strength and high specific stiffness. However, this structure generally suffers from significant low-frequency vibration transmission and slow energy attenuation, affecting the stability and reliability of equipment.

[0003] Existing vibration reduction methods are divided into two categories: active control and passive control. Active control relies on external energy and complex systems. Although it can accurately suppress vibrations in specific frequency bands, the system is complex and has poor environmental adaptability. Passive control has a simple and reliable structure, but its low-frequency vibration reduction effect is limited and is often accompanied by a decrease in load-bearing capacity.

[0004] In recent years, metamaterials have brought new opportunities for vibration control. Through periodic microstructure design, band gaps that suppress elastic wave propagation can be generated. Among them, local resonant metamaterials can achieve low-frequency control at the subwavelength scale. However, existing schemes that combine local resonant units with sandwich structures still have limitations: surface-attached types destroy structural integrity and functionality, while embedded plate types weaken load-bearing capacity and are difficult to simultaneously meet the requirements of low-frequency and broadband vibration reduction. Summary of the Invention

[0005] The present invention improves upon the above-mentioned problems by providing a body-centered cubic sandwich superstructure with low-frequency broadband characteristics and its working method. Through a clever built-in design, the Archimedes spiral beam oscillator unit is embedded in the body-centered cubic sandwich frame, which can generate a significant bending wave bandgap in the low-frequency band by utilizing the multimodal local resonance mechanism without damaging the panel surface.

[0006] The present invention is constructed as follows: it includes multiple unit cell structures arranged periodically along the X and Y directions. Each unit cell structure includes an upper panel, an internal truss structure, and a lower panel arranged sequentially from top to bottom. A helical beam-mass block local resonance unit is provided at the body center position of the internal truss structure. The helical beam-mass block local resonance unit includes at least one Archimedean helical beam and a mass block. One end of the Archimedean helical beam is fixed to the mass block, and the other end is fixed to the body center node of the internal truss structure.

[0007] Furthermore, the internal truss structure includes an upper truss and a lower truss, both of which are formed by multiple columns. One end of each column is fixed to the upper panel or the lower panel, and the other end of each column is connected as a whole.

[0008] Furthermore, the mass block is cylindrical.

[0009] Furthermore, multiple Archimedes' helical beams are arranged within the unit cell structure to form a multi-oscillator synergistic effect.

[0010] Furthermore, two rows of unit cell structures are arranged along the Y direction, and each row of unit cell structures has twenty-eight units arranged along the X direction.

[0011] Furthermore, the upper and lower panels each have a side length of 46mm and a thickness of 0.5mm; the internal truss structure has a height of 19mm; the Archimedes spiral beam has a starting radius of 2mm, an ending radius of 16mm, a thickness of 2mm, and a width of 1mm; the mass block has a diameter of 12mm and a height of 10mm.

[0012] Furthermore, the upper and lower panels and the internal truss structure are made of aluminum alloy with a Young's modulus of 69 GPa, a density of 2713 kg / m³, and a Poisson's ratio of 0.3; the Archimedes' spiral beam is made of stainless steel with a Young's modulus of 193 GPa, a density of 8027 kg / m³, and a Poisson's ratio of 0.3; and the mass block is made of lead with a Young's modulus of 17 GPa, a density of 11340 kg / m³, and a Poisson's ratio of 0.42. The overall density of the structure is 573.512 kg / m³.

[0013] Furthermore, the upper panel and the internal truss structure, the internal truss structure and the lower panel, the internal truss structure and the spiral beam-mass block local resonance unit, and the Archimedes spiral beam and the mass block are all welded or bonded.

[0014] Furthermore, the working method of the body-centered cubic sandwich superstructure with low-frequency broadband characteristics is as follows: when a low-frequency bending wave propagates through the upper or lower panel of the unit cell structure, the internal truss structure will transmit the excitation to the Archimedean spiral beam and cylindrical oscillator of the spiral beam-mass block local resonant unit, exciting its multimodal vibration. These modes are coupled with the elastic wave to form a band gap that suppresses wave propagation.

[0015] Furthermore, during the multimodal vibration of the helical beam-mass block local resonant unit, its multimodal vibration includes in-plane oscillation, torsion, and out-of-plane vibration, which facilitates coupling with the bending waves propagating through the upper and lower panels, and generates a bending wave bandgap in the low-frequency band based on the local resonance mechanism.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) High structural integration and functional integration: The spiral beam-mass block local resonance unit is embedded in the core cubic frame of the load-bearing body, realizing the integrated design of vibration reduction and load bearing, and maintaining the core advantages of traditional sandwich panels such as flat surface, light weight and high strength.

[0017] (2) Outstanding low-frequency broadband performance: The unique geometric configuration of the Archimedes spiral beam of the spiral beam-mass block local resonance unit is used to excite multimodal local resonance. Through strong coupling with the bending waves of the upper and lower panels, a wide bandwidth can be generated in the low-frequency band, which solves the problem of insufficient low-frequency suppression bandwidth of traditional structures. Without sacrificing the advantages of lightweight and high strength of the sandwich structure, low-frequency broadband vibration reduction is achieved through embedded design.

[0018] (3) Strong designability and controllability: Clear parameter control rules have been established. The center frequency and width of the band gap can be precisely controlled by changing limited geometric or material parameters. The position and width of the band gap can be precisely controlled by adjusting the lattice constant, core layer height, helical beam geometric parameters or material properties, so as to meet the customized needs of different engineering scenarios.

[0019] (4) Good engineering practicality: The structure concept is clear and has broad application prospects in fields such as aerospace, ships, and high-speed vehicles where there are strict requirements for lightweighting and low-frequency vibration control. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall body-centered cubic sandwich superstructure according to an embodiment of the present invention; Figure 2 for Figure 1 A magnified view of a section at point A in the middle; Figure 3 This is a schematic diagram of a single-cell structure according to an embodiment of the present invention; Figure 4 This is an exploded view of the unit cell structure of an embodiment of the present invention; Figure 5 This is a schematic diagram of the helical beam-mass block local resonance unit structure according to an embodiment of the present invention; Figure 6 This is a band structure diagram of the body-centered cubic superstructure according to an embodiment of the present invention; Figure 7 The simulated vibration transmission curves of the metamaterial beam structure with a 2×28-unit period in Embodiment 2 of the present invention are shown. Figure 8 This is a transient response diagram of a simple harmonic displacement excitation at a frequency of 99Hz within the bandgap according to an embodiment of the present invention. Figure 9 This is a transient response diagram of a simple harmonic displacement excitation at a passband frequency of 182Hz according to an embodiment of the present invention. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] Example: Refer to Appendix Figure 1-9As shown, a body-centered cubic sandwich superstructure with low-frequency broadband characteristics is provided. The body-centered cubic sandwich superstructure 100 includes a plurality of unit cell structures 200 arranged periodically along the X and Y directions. The unit cell structure 200 includes an upper panel 210, an internal truss structure 220, and a lower panel 230 arranged sequentially from top to bottom. A helical beam-mass block local resonance unit 240 is provided at the body center position of the internal truss structure. The helical beam-mass block local resonance unit 240 includes at least one Archimedes helical beam 241 and a mass block 242. One end of the Archimedes helical beam is fixed to the mass block, and the other end is fixed to the body center node of the internal truss structure.

[0023] The aforementioned upper and lower panels are two parallel thin plate structures, spaced a predetermined distance apart. The internal truss structure provides support, forming the internal support skeleton of the entire sandwich structure, providing the main load-bearing stiffness and decoupling the motion between the panels and the internal oscillators. The spiral beam-mass block local resonance unit is located at the body center of the spiral beam-mass block local resonance unit. The Archimedean spiral beam of the spiral beam-mass block local resonance unit is spiral-shaped, with its starting end fixed to the body center node of the internal truss structure and its ending end connected to a cylindrical mass block.

[0024] In this embodiment of the invention, the frequency range of vibration suppression of the sandwich superstructure can be effectively controlled by adjusting the following parameters: lattice constant, thickness of the upper and lower panels, height of the body-centered cubic sandwich layer (i.e., height of the internal truss structure), geometric parameters of the helical beam, size of the mass block, and material properties of each component. By adjusting the bandgap according to the above parameters, a significant bending wave bandgap can be opened in the frequency band below 200Hz, and the normalized bandgap width (the ratio of bandgap width to center frequency) can reach more than 0.6, thereby achieving low-frequency broadband vibration suppression.

[0025] In this embodiment of the invention, the internal truss structure 220 includes an upper truss 221 and a lower truss 222. Both the upper and lower trusses are formed by multiple columns. One end of each column is fixed to the upper panel or the lower panel, and the other end of each column is connected as a whole to form a plane that is fixed to the helical beam-mass block local resonance unit. The internal truss structure serves as a body-centered cubic sandwich layer.

[0026] In this embodiment of the invention, the mass block is cylindrical.

[0027] In this embodiment of the invention, in order to enhance broadband characteristics, multiple Archimedes spiral beams can be introduced into the unit cell. The parameters of each spiral beam can be independently adjusted to form a multi-oscillator synergistic effect. Through the modal superposition principle, multiple oscillators can couple to generate multiple sub-bandgap.

[0028] The unit cell structure contains multiple Archimedes spiral beams.

[0029] Specifically, there are two rows of unit cell structures along the Y direction, and each row of unit cell structures has twenty-eight units along the X direction.

[0030] In this embodiment of the invention, the upper panel and the internal truss structure, the internal truss structure and the lower panel, the internal truss structure and the spiral beam-mass block local resonance unit, and the Archimedes spiral beam and the mass block are all welded or bonded.

[0031] Of course, the body-centered cubic sandwich superstructure can also be manufactured as a single unit. This method utilizes additive manufacturing technology, using metal powder or resin as raw materials to directly print the entire unit cell structure, ensuring precision and seamless integration. Alternatively, if a modular assembly method is used, the upper panel 2, lower panel 3, internal truss structure 4, Archimedes' spiral beam 5, and cylindrical oscillator 6 are fabricated separately, and then assembled using laser welding or adhesive bonding. This structure is suitable for aerospace applications, such as aircraft wings or satellite panels, effectively suppressing low-frequency vibration transmission and improving equipment stability and reliability.

[0032] The materials for the top panel, bottom panel, internal truss structure, and helical beam-mass block local resonance unit can be metal, composite material, or high-performance polymer.

[0033] In this embodiment of the invention, when the body-centered cubic sandwich superstructure with low-frequency broadband characteristics is in operation, when a low-frequency bending wave propagates through the upper or lower panel of the unit cell structure, the internal truss structure will transmit the excitation to the Archimedes spiral beam and cylindrical oscillator of the spiral beam-mass block local resonance unit, exciting its multimodal vibration. These modes are coupled with the elastic wave to form a band gap that suppresses wave propagation.

[0034] During the multimodal vibration of the helical beam-mass block local resonance unit, its multimodal vibration includes in-plane oscillation, torsion and out-of-plane vibration, which facilitates coupling with the bending wave propagating through the upper and lower panels, and generates a bending wave bandgap in the low-frequency band based on the local resonance mechanism.

[0035] By adjusting the lattice constant, the height of the body-centered cubic sandwich layer (i.e., the height of the internal truss structure), the geometric parameters of the helical beam, or the material properties, the position and width of the bandgap can be precisely controlled. For example, increasing the mass of the cylindrical oscillator can widen the bandgap; increasing the rotation angle of the helical beam can lower the bandgap initiation frequency, thereby achieving broadband low-frequency vibration suppression.

[0036] Example 2: Based on Example 1, in this embodiment of the invention, the upper and lower panels are both 46mm in side length and 0.5mm in thickness; the internal truss structure is 19mm in height; the Archimedes spiral beam has a starting radius of 2mm, an ending radius of 16mm, and a thickness and width of 2mm and 1mm respectively; the mass block has a diameter of 12mm and a height of 10mm.

[0037] In this embodiment of the invention, the upper and lower panels and the body-centered cubic core layer are made of aluminum alloy with a Young's modulus of 69 GPa, a density of 2713 kg / m³, and a Poisson's ratio of 0.3; the Archimedes' helical beam is made of stainless steel with a Young's modulus of 193 GPa, a density of 8027 kg / m³, and a Poisson's ratio of 0.3; the mass block is made of lead with a Young's modulus of 17 GPa, a density of 11340 kg / m³, and a Poisson's ratio of 0.42. The overall density of the structure is 573.512 kg / m³. The core layer has a body-centered cubic configuration, meeting the design requirements of lightweight and high strength.

[0038] Based on the above parameters, a simulated band structure analysis is conducted, such as... Figure 6 As shown in the figure, the shaded area represents the bandgap, which ranges from 81.142 to 161.101 Hz. Within this bandgap range, the propagation of elastic waves is suppressed. To verify the accuracy of the calculated bandgap frequency range and the vibration reduction performance of the metamaterial beam, the simulated vibration transmission curve of a 2×28 unit cell period metamaterial beam is calculated as shown in the figure. Figure 7 As shown in the figure, the elastic wave transmission value within the bandgap range exhibits significant attenuation. A transient time-domain calculation was performed at a frequency of 99Hz within the bandgap range, compared to the transient calculation at 182Hz within the passband. Specifically, a simple harmonic displacement excitation with an amplitude of 1mm was applied to one end of the beam, and the displacement response of the sandwich beam under the aforementioned frequency excitation was calculated. Figure 8 As shown, the results indicate that the transmission of the excitation signal in the passband is unaffected in this structure. Figure 9 As shown, the excitation signal in the bandgap experiences significant attenuation during propagation in this structure. It should be noted that the low-frequency bandwidth of this embodiment reaches 79.959 Hz, and the normalized bandwidth can reach 0.638. Therefore, the sandwich metamaterial beam of this invention possesses excellent low-frequency vibration suppression performance.

[0039] Unless otherwise stated, if any technical solution disclosed in this invention discloses a numerical range, then the disclosed numerical range is a preferred numerical range. Anyone skilled in the art should understand that the preferred numerical range is merely a range of numerical values ​​among many implementable values ​​that have a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this invention discloses only some numerical values ​​to illustrate the technical solutions of this invention. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this invention.

[0040] If the terms "first" or "second" are used in this document to specify components, those skilled in the art should know that the use of "first" or "second" is merely for the purpose of distinguishing components in description, and unless otherwise stated, the above terms have no special meaning.

[0041] Meanwhile, if the present invention discloses or relates to mutually fixedly connected parts or structural components, then unless otherwise stated, fixed connection can be understood as: a fixed connection that can be detached (e.g., using bolts or screws), or a fixed connection that cannot be detached (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured by integral molding using a casting process) (except where it is obviously impossible to use an integral molding process).

[0042] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0043] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A body-centered cubic sandwich superstructure with low-frequency broadband characteristics, characterized in that, It includes multiple unit cell structures arranged periodically along the X and Y directions. Each unit cell structure includes an upper panel, an internal truss structure, and a lower panel arranged sequentially from top to bottom. The body center of the internal truss structure is provided with a helical beam-mass block local resonance unit. The helical beam-mass block local resonance unit includes at least one Archimedes helical beam and a mass block. One end of the Archimedes helical beam is fixed to the mass block, and the other end is fixed to the body center node of the internal truss structure.

2. The body-centered cubic sandwich superstructure with low-frequency broadband characteristics according to claim 1, characterized in that, The internal truss structure includes an upper truss and a lower truss, both of which are formed by multiple columns. One end of each column is fixed to the upper or lower panel, and the other ends of the columns are connected as one unit.

3. A body-centered cubic sandwich superstructure with low-frequency broadband characteristics according to claim 1, characterized in that, The mass block is cylindrical.

4. A body-centered cubic sandwich superstructure with low-frequency broadband characteristics according to claim 1, characterized in that, Multiple Archimedes' helical beams are arranged within the unit cell structure to form a multi-oscillator synergistic effect.

5. A body-centered cubic sandwich superstructure with low-frequency broadband characteristics according to claim 1, characterized in that, There are two rows of unit cell structures along the Y direction, and each row of unit cell structures has twenty-eight units along the X direction.

6. A body-centered cubic sandwich superstructure with low-frequency broadband characteristics according to claim 1, characterized in that, The upper and lower panels each have a side length of 46mm and a thickness of 0.5mm; the internal truss structure has a height of 19mm; the Archimedes spiral beam has a starting radius of 2mm, an ending radius of 16mm, a thickness of 2mm, and a width of 1mm; the mass block has a diameter of 12mm and a height of 10mm.

7. A body-centered cubic sandwich superstructure with low-frequency broadband characteristics according to claim 1, characterized in that, The upper and lower panels and internal truss structure are made of aluminum alloy with a Young's modulus of 69 GPa, a density of 2713 kg / m³, and a Poisson's ratio of 0.

3. The Archimedes' spiral beam is made of stainless steel with a Young's modulus of 193 GPa, a density of 8027 kg / m³, and a Poisson's ratio of 0.

3. The mass block is made of lead with a Young's modulus of 17 GPa, a density of 11340 kg / m³, and a Poisson's ratio of 0.

42. The overall density of the structure is 573.512 kg / m³.

8. A body-centered cubic sandwich superstructure with low-frequency broadband characteristics according to claim 1, characterized in that, The upper panel and the internal truss structure, the internal truss structure and the lower panel, the internal truss structure and the spiral beam-mass block local resonance unit, and the Archimedes spiral beam and the mass block are all welded or bonded.

9. The working method of a body-centered cubic sandwich superstructure with low-frequency broadband characteristics according to claim 1, characterized in that, When a low-frequency bending wave propagates through the upper or lower panel of the unit cell structure, the internal truss structure will transmit the excitation to the Archimedean spiral beam and cylindrical oscillator of the spiral beam-mass block local resonant unit, exciting its multimodal vibration. These modes are coupled with the elastic wave to form a band gap that suppresses wave propagation.

10. The working method of a body-centered cubic sandwich superstructure with low-frequency broadband characteristics according to claim 1, characterized in that, During the multimodal vibration of the helical beam-mass block local resonance unit, its multimodal vibration includes in-plane oscillation, torsion and out-of-plane vibration, which facilitates coupling with the bending wave propagating through the upper and lower panels, and generates a bending wave bandgap in the low-frequency band based on the local resonance mechanism.

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