Periodic negative Poisson's ratio vibration isolation anti-impact structure for ship

Abstract

The periodic negative Poisson's ratio vibration isolation and impact resistance structure for the ship comprises at least one periodic vibration isolation and impact resistance module, and each periodic vibration isolation and impact resistance module comprises two rigid cylindrical shells which are separated from each other up and down and two rigid cylindrical supporting pieces which are coaxially located in the cylindrical shells and are separated from each other up and down; the negative Poisson's ratio energy absorption structures are arranged between the cylindrical shells and the cylindrical supporting pieces and connect the two cylindrical shells with the two cylindrical supporting pieces; the negative Poisson's ratio energy absorption structure is of a rotary structure and comprises a plurality of negative Poisson's ratio cell elements made of elastic materials, and the multiple negative Poisson's ratio cell elements serve as fan-shaped rotary sections and are arranged in the circumferential direction of the axis of the cylindrical supporting piece at intervals. Based on the coupling effect of the negative Poisson's ratio effect and the local resonance mechanism, external vibration energy can be gathered near an excitation source through periodic arrangement of several units in the one-dimensional direction, downward transmission of vibration is effectively restrained, and the vibration isolation performance is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of shipboard raft vibration isolation system technology, and in particular to a periodic negative Poisson's ratio vibration isolation and shock-resistant structure for ships. Background Technology

[0002] As modern ships continue to develop towards larger and lighter designs, the issue of hull structure vibration is becoming increasingly prominent. High-intensity vibration and the noise it radiates not only easily lead to fatigue damage to the hull structure and affect the physical and mental health of the crew, but also seriously weaken the ship's stealth and navigation safety.

[0003] Furthermore, ships inevitably encounter extreme conditions such as wave impacts and grounding during operation, making it equally important to enhance their shock resistance to ensure safety. Floating raft vibration isolation systems, as continuous parametric systems composed of power equipment, the raft hull, upper and lower vibration isolators, and the ship's foundation, can simultaneously isolate vibrations generated by multiple onboard devices and provide reliable protection for the equipment under impact loads. They are one of the key technologies for improving the vibration and shock control capabilities of ships.

[0004] In recent years, mechanical metamaterials based on negative Poisson's ratio cell design have developed through concave, rotational, or chiral configurations. These metamaterials expand laterally when stretched and contract laterally when compressed, creating locally high-density and high-energy-dissipation regions. As a result, they exhibit significantly higher energy absorption efficiency than traditional foam or rubber materials.

[0005] However, existing research on negative Poisson's ratio metamaterials mainly focuses on their energy absorption characteristics under static or quasi-static loads, and a systematic design system for periodic, load-bearing-energy-absorbing integrated systems suitable for floating raft vibration isolation has not yet been established. In particular, in the area of ​​suppressing low-frequency, broadband vibrations of ship hulls, there is still a lack of design methods for periodic structures with adjustable frequencies and controllable band gaps, making it difficult to meet the actual needs for coordinated vibration and shock control under complex operating conditions of ships. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings and defects of existing technologies and provide a periodic negative Poisson's ratio vibration isolation and shock-resistant structure that can be used as the upper and lower layer vibration isolators in a floating raft vibration isolation system. While ensuring load-bearing stiffness, this invention, based on the coupling effect of the negative Poisson's ratio effect and the local resonance mechanism, uses a periodic arrangement of several units in a one-dimensional direction to concentrate external vibration energy near the excitation source, effectively suppressing the downward transmission of vibration, significantly improving vibration isolation performance. Furthermore, the overall structural design is simple, facilitating manufacturing and assembly.

[0007] This invention provides a periodic negative Poisson's ratio vibration isolation and shock-resistant structure for ships, comprising at least one periodic vibration isolation and shock-resistant module. The periodic vibration isolation and shock-resistant module includes two rigid cylindrical shells spaced vertically apart, two rigid cylindrical supports coaxially located inside the cylindrical shells spaced vertically apart, and a negative Poisson's ratio energy-absorbing structure arranged between the cylindrical shells and the cylindrical supports, connecting the two cylindrical shells and the two cylindrical supports. The negative Poisson's ratio energy-absorbing structure is a rotary structure, comprising multiple negative Poisson's ratio cells made of elastic material, and the multiple negative Poisson's ratio cells are arranged circumferentially around the axis of the cylindrical supports as fan-shaped rotary segments.

[0008] Preferably, the cylindrical outer shell is formed by joining two semi-circular shells together with a connector.

[0009] Preferably, the negative Poisson's ratio cell has an elliptical hole at its center and U-shaped notches on both sides of its outer peripheral wall. The upper and lower ends of the U-shaped notches form a shell connecting boss and a support connecting boss. The inner peripheral wall of the cylindrical shell and the outer peripheral wall of the cylindrical support have assembly grooves that are inserted and fitted with the shell connecting boss and the support connecting boss.

[0010] Preferably, the cylindrical support has multiple mounting grooves on its outer peripheral wall, which are circumferentially spaced around the axis of the cylindrical support; the connecting groove on the inner peripheral wall of the semi-circular shell of the cylindrical shell is an arc-shaped groove, which is coaxially arranged with the central axis of the cylindrical shell formed after assembly, and the arc-shaped grooves on the two semi-circular shells form a coaxial annular groove that runs through the entire circumference of the inner peripheral wall of the cylindrical shell when the shells are joined together.

[0011] Preferably, the outer shell connecting boss and the support connecting boss are arranged symmetrically from left to right.

[0012] Preferably, the major axis of the elliptical hole at the center of the negative Poisson's ratio cell is 2-4 times the minor axis.

[0013] Preferably, the negative Poisson's ratio cell has symmetrical concave arc surfaces at its upper and lower ends, and symmetrical convex portions at both ends of the concave arc surfaces. The convex portions at both ends of the upper concave arc surface are respectively connected to the upper shell connecting boss and the support connecting boss through an upper concave arc, and the convex portions at both ends of the lower concave arc surface are respectively connected to the lower shell connecting boss and the support connecting boss through a lower concave arc.

[0014] Preferably, the cylindrical shell and the cylindrical support are made of rigid metal material.

[0015] Preferably, the negative Poisson's ratio cell is formed from a polymer material.

[0016] The cyclic negative Poisson's ratio vibration isolation and shock-resistant structure for ships of the present invention provides the main load-bearing stiffness through the outer ring and central rigid support. The negative Poisson's ratio energy-absorbing structure undergoes lateral contraction and densification under impact load, realizing efficient dissipation of impact energy. In this way, the vibration and impact energy can be dissipated by utilizing the negative Poisson's ratio energy-absorbing units in the middle layer. By arranging this cyclic vibration isolation and shock-resistant structure periodically along a one-dimensional direction, a wideband vibration isolation bandgap can be formed in the low-frequency band based on the principle of local resonance, thereby effectively suppressing typical wideband vibrations of ships, while also having the ability to buffer strong transient impact loads.

[0017] The shipboard periodic negative Poisson's ratio vibration isolation and shock-resistant structure of the present invention can flexibly adjust the overall stiffness and resonant frequency by adjusting the height of the cut-off portion on the cylindrical shell and support, so as to adapt to the vibration isolation and shock resistance requirements under different working conditions. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a single-cycle three-dimensional structure of the present invention.

[0019] Figure 2 This is a schematic diagram of a single-cycle cylindrical shell structure according to the present invention.

[0020] Figure 3 This is a schematic diagram of the single-cycle negative Poisson's ratio energy absorption structure of the present invention.

[0021] Figure 4 This is a cross-sectional view of a two-dimensional negative Poisson's ratio cell in this invention.

[0022] Figure 5 This is a schematic diagram of a single-cycle cylindrical support in this invention.

[0023] Figure 6 This is a diagram illustrating the use of the present invention as an upper and lower layer vibration isolator in a floating raft vibration isolation system.

[0024] Figure 7 This is a comparison chart of the vibration isolation performance of the present invention with the reference results.

[0025] Explanation of reference numerals in the attached figures: 1. Cylindrical outer shell; 1-1. Bolt holes; 2. Negative Poisson's ratio energy absorption structure; 2-1. Cylindrical support connecting boss; 2-2. Negative Poisson's ratio cell; 2-3. Cylindrical shell connecting boss; 3. Cylindrical support; 3-1. Sector-shaped assembly slot; 4. Bottom of the power equipment; 5. Top of the raft. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0027] See Figures 1 to 5 As shown in the exemplary embodiment of this application, the shipboard periodic negative Poisson's ratio vibration isolation and shock-resistant structure includes at least one periodic vibration isolation and shock-resistant module. The periodic vibration isolation and shock-resistant module includes two rigid cylindrical shells 1 spaced apart vertically, two rigid cylindrical supports 3 coaxially located inside the cylindrical shells and spaced apart vertically, and a negative Poisson's ratio energy-absorbing structure 2 arranged between the cylindrical shells and the cylindrical supports and connecting the two cylindrical shells and the two cylindrical supports. The negative Poisson's ratio energy-absorbing structure is a rotary structure, containing multiple negative Poisson's ratio cells 2-2 made of elastic material. The multiple negative Poisson's ratio cells are arranged circumferentially around the axis of the cylindrical supports as fan-shaped rotary segments.

[0028] In this embodiment, the negative Poisson's ratio energy-absorbing structure 2 is formed by rotating a two-dimensional cell with negative Poisson's ratio around a central axis. This two-dimensional cell can cause the structure to shrink towards the center under compressive stress. Its rotation trajectory is a discontinuous fan-shaped ring, so that the negative Poisson's ratio energy-absorbing structure 2 has fan-shaped rotation segments distributed at intervals in the circumferential direction.

[0029] like Figure 2 As shown, the cylindrical shell 1 is a thin-walled hollow component, which is formed by connecting two semi-cylindrical shells through a connector, such as bolt hole 1-1. The semi-cylindrical shells have arc-shaped grooves cut at the connection position with the energy-absorbing structure. The arc-shaped grooves are arranged coaxially with the central axis of the cylindrical shell after being assembled. The arc-shaped grooves on the two semi-cylindrical shells are joined together to form a coaxial annular groove that runs through the entire circumference of the inner wall of the cylindrical shell.

[0030] like Figure 3 As shown, the negative Poisson's ratio energy-absorbing structure 2 is formed by rotating a two-dimensional negative Poisson's ratio cell 2-2 around a central axis. A cylindrical support connecting boss 2-3 is provided at the connection position with the cylindrical support body 3, and a cylindrical shell connecting boss 2-3 is provided at the connection position with the cylindrical shell. These bosses are radial bosses, configured to engage with the annular groove of the cylindrical shell and the fan-shaped assembly groove 3-1 on the cylindrical support, thereby achieving positioning and connection of the three components. When supported by a rigid structure, the negative Poisson's ratio energy-absorbing structure 2 of this application can absorb vibration and impact energy, and its structure is simple and easy to implement.

[0031] Specifically, the arc-shaped grooves on the two semi-cylindrical shells are arranged such that the arc-shaped groove of the upper semi-cylindrical shell is at the bottom and the arc-shaped groove of the lower semi-cylindrical shell is at the top. The two cylindrical shell connecting bosses 2-3 of the two-dimensional negative Poisson's ratio cell 2-2 are respectively assembled with the arc-shaped grooves of the two semi-cylindrical shells. The fan-shaped assembly grooves 3-1 on the two cylindrical supports 3 are arranged adjacently, that is, the fan-shaped assembly groove 3-1 on the upper cylindrical support is at the bottom and the fan-shaped assembly groove 3-1 on the lower cylindrical support is at the top. The two cylindrical support connecting bosses 2-3 of the two-dimensional negative Poisson's ratio cell 2-2 are assembled with the fan-shaped assembly grooves 3-1 on the two cylindrical supports 3.

[0032] In this embodiment, the negative Poisson's ratio energy-absorbing structure 2 is presented in the circumferential direction as several spaced fan-shaped rotating segments, the number of which n can be flexibly set according to actual needs, and its relationship with the rotation angle θ is as follows: .

[0033] like Figure 4 As shown, the two-dimensional negative Poisson ratio cell with negative Poisson bit properties can be formed by centrally symmetrically opening elliptical holes on the cross-section of a cube. For example, in this embodiment, the length of the major axis of the elliptical hole is 3 times the length of the minor axis.

[0034] In some embodiments, see Figure 4 As shown, the negative Poisson's ratio cell has symmetrical concave arc surfaces at its upper and lower ends, and symmetrical convex portions at both ends of the concave arc surfaces. The convex portions at both ends of the upper concave arc surface are respectively connected to the upper shell connecting boss and the support connecting boss through an upper concave arc. The convex portions at both ends of the lower concave arc surface are respectively connected to the lower shell connecting boss and the support connecting boss through a lower concave arc.

[0035] like Figure 5 As shown, the height of the cylindrical support 3 is the same as that of the cylindrical shell 1, and its height can be flexibly set according to actual needs. Multiple fan-shaped assembly slots 3-1 are cut out at the connection position with the negative Poisson's ratio energy absorption structure 2.

[0036] like Figure 6 As shown, the structure of this invention, arranged periodically along a one-dimensional direction as a unit structure, can be used as the upper and lower layer vibration isolators in a floating raft vibration isolation system. Depending on the selected number of periods, the negative Poisson's ratio energy-absorbing structure 2 of the middle layer of multiple periodic units is integrally formed; that is, when manufacturing the multiple negative Poisson's ratio cells of the middle layer negative Poisson's ratio energy-absorbing structure, they are stacked vertically and integrally formed into a single unit. Figure 4 For example, f is a structure in which multiple cells in the vertical direction are arranged one-dimensionally and connected together to form the required negative Poisson's ratio energy absorption structure. Each periodic unit contains a cylindrical support connecting boss 2-1 and a cylindrical shell connecting boss 2-3, which are respectively connected to the corresponding internal cylindrical support 3 and cylindrical shell 1 to form the overall structure.

[0037] When used as an upper vibration isolator, its upper end face is fixedly connected to the bottom 4 of the power equipment, and its lower end face is fixedly connected to the top 5 of the raft; that is, it is located between the bottom of the power equipment and the top of the raft. When used as a lower vibration isolator, its upper end face is fixedly connected to the bottom of the raft, and its lower end face is fixedly connected to the top of the ship foundation; that is, it is located between the bottom of the raft and the top of the ship foundation.

[0038] In a preferred embodiment, the cylindrical outer shell 1 and the cylindrical support 3 are made of alloy steel; the negative Poisson's ratio energy-absorbing structure 2 is made of rubber.

[0039] like Figure 7 As shown, by establishing a finite element model, the calculation is performed when... Figure 6 The vibration level difference between the upper and lower surfaces of the structure, which contains five periodic units, is used to verify its vibration isolation performance when the upper surface is excited. Calculations show that, compared with rubber vibration isolators of the same height and diameter, the vibration level difference of this structure is significantly improved, demonstrating excellent broadband vibration isolation capability.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the invention.

[0041] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A periodic negative Poisson's ratio vibration isolation and shock-resistant structure for ships, characterized in that, The system includes at least one periodic vibration isolation and shock-resistant module. The periodic vibration isolation and shock-resistant module includes two rigid cylindrical shells spaced vertically apart, two rigid cylindrical supports coaxially located inside the cylindrical shells spaced vertically apart, and a negative Poisson's ratio energy-absorbing structure arranged between the cylindrical shells and the cylindrical supports, connecting the two cylindrical shells and the two cylindrical supports. The negative Poisson's ratio energy-absorbing structure is a rotary structure containing multiple negative Poisson's ratio cells made of elastic material. The multiple negative Poisson's ratio cells are arranged circumferentially around the axis of the cylindrical supports as fan-shaped rotary segments.

2. The shipboard periodic negative Poisson's ratio vibration isolation and shock-resistant structure according to claim 1, characterized in that, The cylindrical outer shell is formed by joining two semi-circular shells together with a connector.

3. The shipboard periodic negative Poisson's ratio vibration isolation and shock-resistant structure according to claim 2, characterized in that, The negative Poisson's ratio cell has an elliptical hole at its center and U-shaped notches on both sides of its outer peripheral wall. The upper and lower ends of the U-shaped notches form a shell connecting boss and a support connecting boss. The inner peripheral wall of the cylindrical shell and the outer peripheral wall of the cylindrical support have assembly grooves that are inserted and fitted with the shell connecting boss and the support connecting boss.

4. The shipboard periodic negative Poisson's ratio vibration isolation and shock-resistant structure according to claim 3, characterized in that, The cylindrical support has multiple assembly grooves on its outer peripheral wall, which are arranged circumferentially around the axis of the cylindrical support. The connecting groove on the inner peripheral wall of the semi-circular shell of the cylindrical outer shell is an arc-shaped groove. This arc-shaped groove is coaxially arranged with the central axis of the cylindrical outer shell after assembly, and the arc-shaped grooves on the two semi-circular shells are joined together to form a coaxial annular groove that runs through the entire circumference of the inner peripheral wall of the cylindrical outer shell.

5. The shipboard periodic negative Poisson's ratio vibration isolation and shock-resistant structure according to claim 3, characterized in that, The outer shell connecting boss and the support connecting boss are arranged symmetrically from left to right.

6. The shipboard periodic negative Poisson's ratio vibration isolation and shock-resistant structure according to claim 3, characterized in that, The major axis of the elliptical hole at the center of the negative Poisson's ratio cell is 2-4 times the minor axis.

7. The shipboard periodic negative Poisson's ratio vibration isolation and shock-resistant structure according to claim 3, characterized in that, The negative Poisson's ratio cell has symmetrical concave arc surfaces at its upper and lower ends, and symmetrical convex portions at both ends of the concave arc surfaces. The convex portions at both ends of the upper concave arc surface are respectively connected to the upper shell connecting boss and the support connecting boss through an upper concave arc. The convex portions at both ends of the lower concave arc surface are respectively connected to the lower shell connecting boss and the support connecting boss through a lower concave arc.

8. The shipboard periodic negative Poisson's ratio vibration isolation and shock-resistant structure according to claim 1, characterized in that, The cylindrical outer shell and cylindrical support are made of rigid metal material.

9. The periodic negative Poisson's ratio vibration isolation and shock-resistant structure for ships according to claim 1, characterized in that, The negative Poisson's ratio cell is formed from polymer materials.

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