Tubular energy-absorbing structure based on bimodal compression-torsion coupling

Abstract

The application discloses a negative Poisson's ratio tubular energy-absorbing structure based on bimodal compression-torsion coupling and belongs to the technical field of mechanical metamaterials and structural engineering shock absorption. The application comprises an outer shell, an upper inner ring, a lower inner ring, an upper end frame plate, a lower end frame plate and a support rod. The upper end frame plate and the lower end frame plate are coaxially arranged in a top-down manner, and the outer shell is installed between the opposite end faces of the upper end frame plate and the lower end frame plate. The upper inner ring and the lower inner ring are coaxially arranged in a top-down manner inside the outer shell, and an axial spacing exists between the end faces of the upper inner ring and the lower inner ring. The upper inner ring is connected with the coaxially arranged upper end frame plate through a first group of support rods arranged in an inclined manner, and the lower inner ring is connected with the coaxially arranged lower end frame plate through a second group of support rods arranged in an inclined manner. The application ingeniously combines the heterogeneous bimodal mechanism of "outer layer negative Poisson's ratio compression shrinkage torsion" and "inner layer inclined bracing independent compression torsion", and significantly improves the impact resistance and energy-absorbing characteristics of the structure.

Description

Technical Field

[0001] This invention belongs to the field of mechanical metamaterials and structural engineering vibration reduction and impact resistance technology, specifically involving a negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling. Background Technology

[0002] Compression-torsion coupled mechanical metamaterials have attracted much attention due to their unique deformation mechanisms. These metamaterials, through specific microscopic topological designs, transform axial compressive loads into internal rotational motion. Due to their unique shear-compression coupling effect, they show great potential in aerospace cushioning, vehicle collision protection, and efficient energy dissipation. Based on different deformation-inducing mechanisms, existing compression-torsion metamaterials are mainly divided into four categories: first, chiral and anti-chiral structures relying on the coordinated rotation of rigid nodes; second, inclined truss or bracing structures utilizing the geometric inclination angles of the rods for force vector decomposition; third, pre-torsion / spiral structures based on preset geometric torsion angles or helical paths; and fourth, origami / paper-cutting metamaterials based on rigid origami theory, where the surfaces do not deform but only rotate along the creases. While these traditional configurations can achieve the conversion from compression to torsion and extend the stress wave propagation path, they generally suffer from the following technical bottlenecks: First, the mechanical response mode is singular, lacking multi-level impact resistance. Existing compression-torsion metamaterials mostly employ a single deformation-inducing mechanism (such as pure chirality or pure bracing), and under quasi-static or dynamic compression, their force-displacement curves typically exhibit only a long and single yield plateau. This monotonous energy absorption characteristic cannot meet the needs of complex working conditions. Secondly, there are issues with modal interference and rotational constraints during the deformation process of multi-level nested structures. To improve the energy absorption capacity per unit volume, multi-layer coaxial nested designs are widely used in thin-walled tubes or lattice structures. Except for some two-dimensional chiral networks with spontaneous contraction characteristics, most compression-torsion structures based on inclined rods or macroscopic helical pre-torsion designs exhibit positive Poisson's ratio characteristics. Due to the "bulging" phenomenon under compression, these structures inevitably experience disordered lateral expansion and cell distortion during axial crushing. For nested systems that rely on the "compression-torsion" mechanism for energy dissipation, this radial expansion causes the inner structure to squeeze the outer layer outward, triggering premature and irregular rigid interference. This not only severely restricts the rotational degrees of freedom within the structure and disrupts the torsional force transmission path, but also induces macroscopic overall instability, significantly reducing the energy absorption efficiency of the nested system.

[0003] Negative Poisson's ratio metamaterials are a class of advanced mechanical metamaterials with counterintuitive deformation properties. Their core characteristic is that under axial compressive loads, the structure undergoes lateral contraction, rather than the lateral expansion of traditional materials. This property does not stem from the material's inherent chemical properties but rather from its unique microscopic geometric topology (such as concave honeycombs, double arrowheads, etc.), allowing the structure to alter its porosity during deformation through the indentation of ligaments or the rotation of nodes. Compared to traditional positive Poisson's ratio structures, negative Poisson's ratio metamaterials, while exhibiting excellent shear resistance and energy absorption efficiency under impact by achieving material aggregation and densification in the stressed region, also suffer from limitations due to their weak load-bearing stiffness and singular energy dissipation path. Traditional two-dimensional negative Poisson's ratio cells (such as concave hexagons) dissipate energy primarily through in-plane bending or hinged deformation of the cell walls under axial compression. This singular translational deformation mode results in weak initial load-bearing stiffness and a rapid loss of buffering capacity after the structure reaches densification, failing to provide sustained high-level resistance during long-stroke compression.

[0004] Therefore, how to perfectly couple the "spatial rotation" mechanism of compression and torsion with the "compression-induced inward compaction" of negative Poisson's ratio in a nested structure, in order to broaden the energy dissipation path and achieve multi-order mechanical response, has become a key technical problem that urgently needs to be solved in the field of advanced passive protection. Summary of the Invention

[0005] In response to the aforementioned technical shortcomings of existing compression-torsion metamaterials, such as a single mechanical response mode, the tendency of multi-level nested structures to experience radial expansion (bulging) interference leading to rotational limitations, and the weak load-bearing stiffness and short energy dissipation path of simple negative Poisson's ratio structures, this invention provides a dual-mode compression-torsion coupled negative Poisson's ratio tubular energy-absorbing structure.

[0006] The technical solution of this invention is:

[0007] A negative Poisson's ratio tubular energy-absorbing structure based on dual-mode pressure-torsion coupling includes an outer shell 1, an upper inner ring 2, a lower inner ring 3, an upper frame plate 4, a lower frame plate 5, and a support rod 6.

[0008] The upper frame plate 4 and the lower frame plate 5 are arranged coaxially, and the outer shell 1 is installed between the opposite end faces of the upper frame plate 4 and the lower frame plate 5.

[0009] The upper inner ring 2 and the lower inner ring 3, located inside the outer shell 1, are arranged coaxially and vertically, and there is an axial gap between the end faces of the upper inner ring 2 and the lower inner ring 3; the upper inner ring 2 is connected to the coaxially arranged upper frame plate 4 through the first set of inclined support rods 6, and the lower inner ring 3 is connected to the coaxially arranged lower frame plate 5 through the second set of inclined support rods 6.

[0010] Furthermore, the first group of inclined support rods 6 and the second group of inclined support rods 6 have the same or opposite rotation directions.

[0011] Furthermore, the outer shell 1 is formed into a cylinder by circumferentially curling the arrayed two-dimensional negative Poisson's ratio cells 7.

[0012] Furthermore, a pre-twist angle of [0°, 30°] is applied to the cylinder rolled up circumferentially; where 0° corresponds to the state without pre-twist.

[0013] Furthermore, the two-dimensional negative Poisson's ratio cell 7 includes:

[0014] The concave hexagonal negative Poisson's ratio structure includes horizontal cell wall I8-1, horizontal cell wall II8-2, angled cell wall I8-3, and angled cell wall II8-4. The two concave angled cell walls I8-3 and II8-4 are arranged opposite each other, and the two sides of them are horizontal cell walls I8-1 and II8-2 arranged oppositely and in parallel.

[0015] The extended wall group includes extended walls I9-1 and II9-2 arranged symmetrically based on a concave hexagonal negative Poisson's ratio structure. Both extended walls I9-1 and II9-2 are arranged horizontally with the horizontal cell walls I8-1 and II8-2. One end of extended wall I9-1 is connected to the concave vertex of the included angle cell wall I8-3, and one end of extended wall II9-2 is connected to the concave vertex of the included angle cell wall II8-4.

[0016] The arcuate ligament group includes arcuate ligament I10-1 and arcuate ligament II10-2. Arcuate ligament I10-1 and arcuate ligament II10-2 are arranged concavely inside the concave hexagonal negative Poisson's ratio structure. One end of arcuate ligament I10-1 and arcuate ligament II10-2 is connected to the horizontal cell wall I8-1, and the other end of arcuate ligament I10-1 and arcuate ligament II10-2 is connected to the horizontal cell wall II8-2.

[0017] Two sets of arc-shaped ribs, one set of arc-shaped ribs connected to extension wall I9-1, and the other set of arc-shaped ribs connected to extension wall II9-2. Each set of arc-shaped ribs includes arc-shaped rib I11-1 and arc-shaped rib II11-2. The set of arc-shaped ribs connected to extension wall I9-1 is described as follows: one end of arc-shaped ribs I11-1 and II11-2, which are convex and arranged vertically, is connected to extension wall I9-1, and the other end of arc-shaped ribs I11-1 and II11-2, which are convex, is flush with the horizontal cell wall on the corresponding side.

[0018] The straight rib group includes straight ribs I12-1 and II12-2 arranged at an angle. Straight rib I12-1 starts and ends at the other end of the extension wall I9-1 and the horizontal cell wall I8-1, and is connected in sequence to the arc-shaped rib I11-1 connected to the extension wall I9-1, the upper cell wall of the angled cell wall I8-3, and the arc-shaped ligament I10-1. Straight rib II12-2 starts and ends at the other end of the horizontal cell wall II8-2 and the extension wall II9-2, and is connected in sequence to the arc-shaped ligament II10-2, the lower cell wall of the angled cell wall II8-4, and the arc-shaped rib II11-2 connected to the extension wall II9-2.

[0019] Furthermore, for the two-dimensional negative Poisson's ratio cell 7 of the array arrangement:

[0020] In two adjacent two-dimensional negative Poisson's ratio cells 7, the arc-shaped rib II11-2 of the upper two-dimensional negative Poisson's ratio cell 7 is connected to the arc-shaped rib I11-1 of the lower two-dimensional negative Poisson's ratio cell 7; the straight rib II12-2 of the upper two-dimensional negative Poisson's ratio cell 7 is connected to the straight rib I12-1 of the lower two-dimensional negative Poisson's ratio cell 7; the horizontal cell wall II8-2 of the upper two-dimensional negative Poisson's ratio cell 7 is connected to the horizontal cell wall I8-1 of the lower two-dimensional negative Poisson's ratio cell 7.

[0021] In the two adjacent two-dimensional negative Poisson's ratio cells 7, the extension wall II9-2 of the left two-dimensional negative Poisson's ratio cell 7 is connected to the extension wall I9-1 of the right two-dimensional negative Poisson's ratio cell 7, and the straight rib II12-2 of the left two-dimensional negative Poisson's ratio cell 7 is connected to the straight rib I12-1 of the right two-dimensional negative Poisson's ratio cell 7.

[0022] Furthermore, the upper frame plate 4 and the lower frame plate 5 have the same structure, both including: a first circular ring 13 and a six-chiral structure, wherein the six-chiral structure is connected to the inner ring of the first circular ring 13.

[0023] Furthermore, the six-chiral structure includes a second ring member 14 and six extension arms 15. The second ring member 14 is concentric with the first ring member 13, and the outer ring of the second ring member 14 is connected to the inner ring of the first ring member 13 by six extension arms 15 arranged at an angle.

[0024] The beneficial effects of this invention are:

[0025] 1. This invention innovatively combines two different compression and torsion mechanisms: an outer shell and an inner nested compression and torsion structure, which causes differential torsion between the inner and outer layers, transforming unidirectional axial impact into three-dimensional composite stress, thereby significantly widening the energy dissipation path and improving energy absorption.

[0026] 2. This invention reserves axial spacing in the inner nested compression-torsion structure, allowing the outer layer to provide a flexible buffer during the initial compression phase. Once the spacing closes, the stiffness of the inner and outer layers is superimposed, achieving a stepped mechanical response of "soft first, then stiff." Furthermore, the trigger point of the platform can be flexibly adjusted by regulating the axial spacing, adapting to application scenarios with different impact intensities.

[0027] 3. Through ingenious structural design, the present invention enables the outer tubular structure to possess both compressive and torsional properties as well as negative Poisson's ratio characteristics, significantly improving the structure's impact resistance and energy absorption characteristics. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the negative Poisson's ratio tubular energy-absorbing structure based on dual-mode pressure-torsion coupling of the present invention.

[0029] Figure 2 This is a partial three-dimensional cross-sectional view of the overall structure of the present invention.

[0030] Figure 3 This is a front longitudinal sectional view of the overall structure of the present invention.

[0031] Figure 4 This is a schematic diagram of the outer shell structure of the present invention.

[0032] Figure 5 A schematic diagram of a two-dimensional negative Poisson's ratio cell array.

[0033] Figure 6 This is a schematic diagram of a single two-dimensional negative Poisson's ratio cell.

[0034] Figure 7 This is a structural diagram of a modified embodiment of the present invention without pre-torsion.

[0035] Figure 8 This is a structural diagram of an embodiment of the present invention without straight ribs.

[0036] Figure 9 This is a comparison diagram of the force-displacement curves of comparative test 1 of the present invention.

[0037] Figure 10 This is a comparison diagram of the force-displacement curves of comparative test 2 of the present invention.

[0038] Figure 11 This is a comparison diagram of the force-displacement curves from comparative test 3 of the present invention.

[0039] Figure 12 This is a specific energy absorption curve of the structure of the present invention.

[0040] The labels in the figure are as follows: 1. Outer shell; 2. Upper inner ring; 3. Lower inner ring; 4. Upper frame plate; 5. Lower frame plate; 6. Support rod; 7. Two-dimensional negative Poisson's ratio cell; 8-1. Horizontal cell wall I; 8-2. Horizontal cell wall II; 8-3. Angle cell wall I; 8-4. Angle cell wall II; 9-1. Extension wall I; 9-2. Extension wall II; 10-1. Arc-shaped ligament I; 10-2. Arc-shaped ligament II; 11-1. Arc-shaped rib I; 11-2. Arc-shaped rib II; 12-1. Straight rib I; 12-2. Straight rib II; 13. First ring component; 14. Second ring component; 15. Extension arm. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0042] Example 1: As Figures 1-12 As shown, a negative Poisson's ratio tubular energy-absorbing structure based on dual-mode pressure-torsion coupling includes an outer shell 1, an upper inner ring 2, a lower inner ring 3, an upper frame plate 4, a lower frame plate 5, and a support rod 6.

[0043] The upper frame plate 4 and the lower frame plate 5 are arranged coaxially, and the outer shell 1 is installed between the opposite end faces of the upper frame plate 4 and the lower frame plate 5.

[0044] The upper inner ring 2 and the lower inner ring 3, located inside the outer shell 1, are arranged coaxially and vertically, and there is an axial distance h between the end faces of the upper inner ring 2 and the lower inner ring 3. The upper inner ring 2 is connected to the coaxially arranged upper frame plate 4 through the first set of inclined support rods 6, and the lower inner ring 3 is connected to the coaxially arranged lower frame plate 5 through the second set of inclined support rods 6, forming an inner nested compression and torsion structure.

[0045] Furthermore, the first group of inclined support rods 6 and the second group of inclined support rods 6 have the same or opposite rotation directions. Preferably, the first group of inclined support rods 6 and the second group of inclined support rods 6 have opposite rotation directions, forming a pair of inner nested compression-torsion structures with opposite properties.

[0046] Furthermore, the outer shell 1 is formed into a cylinder by circumferentially curling the arrayed two-dimensional negative Poisson's ratio cells 7.

[0047] Furthermore, a pre-twist angle of [0°, 30°] (e.g., 0°, 20°, 30°) is applied to the cylinder rolled circumferentially. It should be noted that 0° corresponds to the state without pre-twist.

[0048] Furthermore, such as Figure 6 , Figure 7 As shown, the two-dimensional negative Poisson's ratio cell 7 includes:

[0049] The concave hexagonal negative Poisson's ratio structure includes horizontal cell walls I8-1, II8-2, angled cell walls I8-3, and II8-4. The two concave angled cell walls I8-3 and II8-4 are arranged opposite each other, with horizontal cell walls I8-1 and II8-2 arranged parallel to each other on both sides. The angled cell walls I8-3 and II8-4 have the same structure, each including an upper cell wall and a lower cell wall, with one end of the upper cell wall connected to one end of the lower cell wall at an angle.

[0050] The extended wall group includes extended walls I9-1 and II9-2 arranged symmetrically based on a concave hexagonal negative Poisson's ratio structure. Both extended walls I9-1 and II9-2 are arranged horizontally with the horizontal cell walls I8-1 and II8-2. One end of extended wall I9-1 is connected to the concave vertex of the included angle cell wall I8-3, and one end of extended wall II9-2 is connected to the concave vertex of the included angle cell wall II8-4.

[0051] The arcuate ligament group includes arcuate ligament I10-1 and arcuate ligament II10-2. Arcuate ligament I10-1 and arcuate ligament II10-2 are arranged concavely inside the concave hexagonal negative Poisson's ratio structure. One end of arcuate ligament I10-1 and arcuate ligament II10-2 is connected to the horizontal cell wall I8-1, and the other end of arcuate ligament I10-1 and arcuate ligament II10-2 is connected to the horizontal cell wall II8-2.

[0052] Two sets of arc-shaped ribs are provided. One set connects to extension wall I9-1, and the other set connects to extension wall II9-2. Each set of arc-shaped ribs includes arc-shaped rib I11-1 and arc-shaped rib II11-2. The set connected to extension wall I9-1 is described as follows: Arc-shaped ribs I11-1 and II11-2, which are convex and arranged vertically, have one end connected to extension wall I9-1 (one end of arc-shaped rib I11-1 connects to the upper surface of extension wall I9-1, and one end of arc-shaped rib II11-2 connects to the corresponding lower surface of extension wall I9-1). The other end of arc-shaped ribs I11-1 and II11-2 connects to the corresponding side of the water... The cell walls are flush (the upper end face of the arc-shaped rib I11-1 is flush with the upper end face of the horizontal cell wall I8-1, and the lower end face of the arc-shaped rib II11-2 is flush with the lower end face of the horizontal cell wall II8-2); the arc-shaped ribs connected to the extension wall II9-2 are described as follows: the arc-shaped ribs I11-1 and II11-2, which are convex and arranged vertically, are connected at one end to the extension wall II9-2 ((one end of the arc-shaped rib I11-1 is connected to the upper end face of the extension wall II9-2, and one end of the arc-shaped rib II11-2 is connected to the lower end face of the corresponding part of the extension wall II9-2)), and the other end of the arc-shaped ribs I11-1 and II11-2, which are convex, is flush with the horizontal cell wall on the corresponding side.

[0053] The straight rib group includes straight ribs I12-1 and II12-2 arranged at an angle. Straight rib I12-1 starts and ends at the other end of the extension wall I9-1 and the horizontal cell wall I8-1, and is connected in sequence to the arc-shaped rib I11-1 connected to the extension wall I9-1, the upper cell wall of the angled cell wall I8-3, and the arc-shaped ligament I10-1. Straight rib II12-2 starts and ends at the other end of the horizontal cell wall II8-2 and the extension wall II9-2, and is connected in sequence to the arc-shaped ligament II10-2, the lower cell wall of the angled cell wall II8-4, and the arc-shaped rib II11-2 connected to the extension wall II9-2.

[0054] Furthermore, such as Figure 6 As shown, for the two-dimensional negative Poisson's ratio cell 7 arranged in the array:

[0055] In two adjacent two-dimensional negative Poisson's ratio cells 7, the arc-shaped rib II11-2 of the upper two-dimensional negative Poisson's ratio cell 7 is connected to the arc-shaped rib I11-1 of the lower two-dimensional negative Poisson's ratio cell 7; the straight rib II12-2 of the upper two-dimensional negative Poisson's ratio cell 7 is connected to the straight rib I12-1 of the lower two-dimensional negative Poisson's ratio cell 7; the horizontal cell wall II8-2 of the upper two-dimensional negative Poisson's ratio cell 7 is connected to the horizontal cell wall I8-1 of the lower two-dimensional negative Poisson's ratio cell 7.

[0056] In the two adjacent two-dimensional negative Poisson's ratio cells 7, the extension wall II9-2 of the left two-dimensional negative Poisson's ratio cell 7 is connected to the extension wall I9-1 of the right two-dimensional negative Poisson's ratio cell 7, and the straight rib II12-2 of the left two-dimensional negative Poisson's ratio cell 7 is connected to the straight rib I12-1 of the right two-dimensional negative Poisson's ratio cell 7.

[0057] Furthermore, such as Figure 1 , Figure 2 As shown, the upper frame plate 4 and the lower frame plate 5 have the same structure, both including: a first circular ring 13 and a six-chirp structure, wherein the six-chirp structure is connected to the inner ring of the first circular ring 13. In specific installation, the upper inner ring 2 is connected to the six-chirp structure of the upper frame plate 4 via a first set of inclined support rods 6, and the lower inner ring 3 is connected to the six-chirp structure of the lower frame plate 5 via a second set of inclined support rods 6.

[0058] Furthermore, the six-chiral structure includes a second ring member 14 and six extension arms 15. The second ring member 14 is concentric with the first ring member 13, and the outer ring of the second ring member 14 is connected to the inner ring of the first ring member 13 by the six inclined extension arms 15. The six inclined extension arms 15 in the upper frame plate 4 and the lower frame plate 5 have the same rotation direction. Furthermore, the inner diameter of the second ring member 14 is the same as the inner diameter of the upper inner ring 2 and the lower inner ring 3, and the outer diameter of the upper inner ring 2 and the lower inner ring 3 is larger than the outer diameter of the second ring member 14 to increase the contact area of ​​the upper inner ring 2 and the lower inner ring 3; the maximum outer diameter of the first ring member 13 is larger than the maximum outer diameter of the outer shell 1.

[0059] Furthermore, the negative Poisson's ratio tubular energy-absorbing structure based on dual-mode pressure-torsion coupling proposed in this invention can be made of AL6061 material.

[0060] Furthermore, to verify the structural performance of this invention, a negative Poisson's ratio tubular energy-absorbing structure model based on dual-modal compression-torsional coupling was established using SolidWorks software, and imported into the finite element analysis software Abaqus for quasi-static compression simulation experiments. The overall height of the negative Poisson's ratio tubular energy-absorbing structure based on dual-modal compression-torsional coupling is 58 mm, the outer diameter of the first circular ring 13 is 63 mm, and the material is defined as AL6061. The simulation boundary conditions are set as follows: the bottom is completely fixed, a constant axial compression velocity is applied to the top without restricting rotation, the compression displacement is 40 mm, and the velocity is 20 m / min, simulating a quasi-static compression process, and several sets of comparative experiments were conducted.

[0061] Comparative Experiment 1: The negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling described in this invention (hereinafter referred to as "the structure of this invention") with a 30° pre-torsion angle applied, compared with the structure with a 30° pre-torsion angle applied. Figure 4The difference in mechanical response of the outer shell structure under quasi-static compression conditions is shown.

[0062] To ensure the rigor of the comparison, both structures in Comparative Experiment 1 used the same material, mesh size, contact settings, and simulation boundary conditions. By extracting the support reactions, the following results were obtained: Figure 9 The force-displacement curves are shown in the comparison diagram. Combined with... Figure 9 As can be seen from the force-displacement curves, in the initial compression phase of 0-8mm, the curves of the two components highly overlap and remain in a stable low force range. This directly confirms that the structure of this invention is interference-free, with the outer shell bearing the load only during the initial compression phase. When the compression displacement reaches approximately 8mm (i.e., the reserved gap is compressed and closed), the force-displacement curve of this invention exhibits a steep "stiffness leap," with the force value rapidly increasing and stabilizing at a high plateau of 13-15kN, while the upper limit of the load-bearing capacity of the single outer shell structure is significantly lower (only about 11kN). This significant mechanical difference fully highlights the advantages of the stepped mechanical properties of this invention, proving that by triggering the coordinated compression and torsion of the inner and outer layers through a preset axial spacing h, the energy absorption bottleneck of a single structure can be completely broken, enabling the structure to achieve a leapfrog improvement in resistance to large deformations and overall energy absorption efficiency.

[0063] Comparative Experiment 2: The negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling described in this invention, with a pre-torsion angle of 30°, and Figure 7 The mechanical response differences of the non-pre-torsion structure of the present invention under quasi-static compression conditions are shown.

[0064] To ensure the rigor of the comparison, both structures used the same material, mesh size, contact settings, and simulation boundary conditions. By extracting the support reactions, the following results were obtained: Figure 10 The force-displacement curves are shown in the comparison diagram. Combined with... Figure 10The force-displacement curves show that the structure without pre-torsion exhibits a higher initial first-platform force (approximately 4.5 kN) and a relatively lower second-platform peak value (approximately 11-13 kN). In contrast, the structure of this invention with pre-torsion exhibits a significantly reduced first-platform force (approximately 2.5 kN) and a substantial increase in the second-platform peak value (approximately 15 kN). Furthermore, during simulation, the structure without pre-torsion rotates under the guidance of the straight ribs, and both structures exhibit almost identical deformation processes. This phenomenon indicates that the pre-torsion angle is not an absolute condition determining the presence or absence of a compression-torsion mechanism, but rather a key design parameter that alters the initial geometric stiffness of the structure and the degree of contact reinforcement between the inner and outer layers. As the pre-torsion angle increases, the first platform weakens while the second platform strengthens. In practical engineering applications, this characteristic endows this invention with excellent "performance customizability," allowing for free adjustment of the energy absorption ratio of the two platforms by changing the pre-torsion angle. For example, pre-torsion can be introduced for applications requiring extremely soft buffering and strong intrusion protection with large drop requirements, while pre-torsion can be reduced or eliminated for applications requiring high initial resistance, greatly broadening the application prospects of this structure in various complex vibration reduction scenarios.

[0065] Comparative Experiment 3: The negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling described in this invention with a 30° pre-torsion angle compared to the structure with a 30° pre-torsion angle. Figure 8 The mechanical response differences of the modified straight ribless structure of the present invention (i.e., straight ribless I12-1 and straight rib II12-2) under quasi-static compression conditions are shown.

[0066] To ensure the rigor of the comparison, both structures used the same material, mesh size, contact settings, and simulation boundary conditions. By extracting the support reactions, the following results were obtained: Figure 11 The force-displacement curves are shown in the comparison diagram. Combined with... Figure 11 The force-displacement curves show that the structure's load-bearing capacity collapsed catastrophically after the straight ribs were removed. The initial plateau force was less than 1 kN, and the highest force in the later stages hovered only around 5-6 kN with violent fluctuations, completely losing the stable high-level energy-absorbing plateau of up to 15 kN present in this invention. Furthermore, during simulation, the structure without straight ribs only exhibited extremely weak torsion under compression, and in the later stages of compression, it showed outward bulging with a positive Poisson's ratio. This fully demonstrates that the straight ribs are the necessary mechanical framework for forcing the structure to contract inward, preventing bulging failure, and maintaining stable crushing.

[0067] Combination Figure 12The energy absorption curve of this invention shows that its energy absorption exhibits a typical "nonlinear acceleration" characteristic: in the initial compression stage (0-10mm), the curve slope is gentle, corresponding to the low overload flexible buffer when the outer structure is under single-layer load; when the displacement exceeds 10mm (with the reserved gap closed), the curve slope rises sharply, strongly demonstrating the "differential torsion" and stiffness superposition mechanism induced by the activation of the inner inclined support rod, which greatly broadens the spatial energy dissipation path; when the displacement reaches 40mm, the specific energy absorption is as high as approximately 8.5J / g. This directly confirms that this invention, through ingenious internal and external heterogeneous design, fully exploits the plastic potential of the material without significantly increasing the structural mass, achieving extremely superior lightweight and high-efficiency energy absorption characteristics.

[0068] The aforementioned finite element quasi-static compression comparative tests and specific energy absorption data conclusively demonstrate that this invention, by stimulating differential torsion in the inner and outer layers, efficiently transforms unidirectional axial impact into three-dimensional composite friction and shear dissipation, achieving a leapfrog improvement in ultimate specific energy absorption (SEA) under the same material mass. Furthermore, analysis of Comparative Experiment 2 shows that by freely adjusting the energy absorption ratio of the two platforms by changing the pre-torsion angle, the application prospects of this structure in various complex vibration reduction scenarios are greatly broadened. This structure integrates excellent spatial geometric compatibility, dual-stage operational adaptability, and outstanding lightweight energy absorption efficiency, providing a highly promising advanced mechanical metamaterial solution for vehicle passive safety, aerospace landing cushioning, and impact protection of high-end equipment.

[0069] In summary, the present invention presents a dual-modal compression-torsion coupled negative Poisson's ratio tubular energy-absorbing structure, successfully overcoming the performance bottleneck of traditional compression-torsion and negative Poisson's ratio structures under complex impact conditions. By ingeniously integrating the heterogeneous dual-modal mechanism of "outer layer negative Poisson's ratio compression-contraction torsion" and "inner layer independent compression-torsion with inclined bracing," and pioneering the use of axial spacing h as a mechanical switch, the present invention not only effectively avoids the radial expansion interference easily induced by traditional nested structures, but also achieves a "flexible-then-rigid" stepped intelligent resistance regulation in macroscopic mechanical response.

[0070] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling, characterized in that, It includes an outer shell (1), an upper inner ring (2), a lower inner ring (3), an upper frame plate (4), a lower frame plate (5), and a support rod (6); The upper frame plate (4) and the lower frame plate (5) are arranged coaxially, and an outer shell (1) is installed between the opposite end faces of the upper frame plate (4) and the lower frame plate (5). The upper inner ring (2) and the lower inner ring (3) located inside the outer shell (1) are arranged coaxially and vertically, and there is an axial gap between the end faces of the upper inner ring (2) and the lower inner ring (3); the upper inner ring (2) is connected to the upper frame plate (4) arranged coaxially through the first set of inclined support rods (6), and the lower inner ring (3) is connected to the lower frame plate (5) arranged coaxially through the second set of inclined support rods (6).

2. The negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling according to claim 1, characterized in that, The first set of inclined support rods (6) have the same or opposite rotation direction as the second set of inclined support rods (6).

3. The negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling according to claim 1, characterized in that, The outer shell (1) is formed into a cylinder by circumferentially curling two-dimensional negative Poisson's ratio cells (7) after arraying.

4. The negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling according to claim 3, characterized in that, A pre-twist angle of [0°, 30°] is applied to a cylinder rolled up circumferentially; where 0° corresponds to the state without pre-twist.

5. The negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling according to claim 3, characterized in that, The two-dimensional negative Poisson's ratio cell (7) includes: The concave hexagonal negative Poisson's ratio structure includes horizontal cell wall I (8-1), horizontal cell wall II (8-2), angled cell wall I (8-3), and angled cell wall II (8-4). The two concave angled cell walls I (8-3) and angled cell walls II (8-4) are arranged opposite each other, and the two sides are horizontal cell walls I (8-1) and horizontal cell walls II (8-2) arranged in parallel. The extended wall group includes extended wall I (9-1) and extended wall II (9-2) arranged symmetrically based on a concave hexagonal negative Poisson's ratio structure. Both extended wall I (9-1) and extended wall II (9-2) are arranged horizontally with the horizontal cell wall I (8-1) and horizontal cell wall II (8-2). One end of extended wall I (9-1) is connected to the concave vertex of the angled cell wall I (8-3), and one end of extended wall II (9-2) is connected to the concave vertex of the angled cell wall II (8-4). The arcuate ligament group includes arcuate ligament I (10-1) and arcuate ligament II (10-2). Arcuate ligament I (10-1) and arcuate ligament II (10-2) are arranged concavely inside the concave hexagonal negative Poisson's ratio structure. One end of arcuate ligament I (10-1) and arcuate ligament II (10-2) is connected to horizontal cell wall I (8-1), and the other end of arcuate ligament I (10-1) and arcuate ligament II (10-2) is connected to horizontal cell wall II (8-2). Two sets of arc-shaped ribs, one set of arc-shaped ribs connected to extension wall I (9-1), and the other set of arc-shaped ribs connected to extension wall II (9-2). Each set of arc-shaped ribs includes arc-shaped rib I (11-1) and arc-shaped rib II (11-2). The arc-shaped ribs connected to extension wall I (9-1) are described as follows: one end of arc-shaped rib I (11-1) and arc-shaped rib II (11-2) which are convex and arranged vertically are connected to extension wall I (9-1), and the other end of arc-shaped rib I (11-1) and arc-shaped rib II (11-2) which are convex are flush with the horizontal cell wall on the corresponding side. The straight rib group includes straight rib I (12-1) and straight rib II (12-2) arranged at an angle. Straight rib I (12-1) starts and ends at the other end of the extension wall I (9-1) and the horizontal cell wall I (8-1), and is connected in sequence to the arc-shaped rib I (11-1) connected to the extension wall I (9-1), the upper cell wall of the angled cell wall I (8-3), and the arc-shaped ligament I (10-1). Straight rib II (12-2) starts and ends at the other end of the horizontal cell wall II (8-2) and the extension wall II (9-2), and is connected in sequence to the arc-shaped ligament II (10-2), the lower cell wall of the angled cell wall II (8-4), and the arc-shaped rib II (11-2) connected to the extension wall II (9-2).

6. The negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling according to claim 5, characterized in that, For the two-dimensional negative Poisson's ratio cell (7) of the array arrangement: In two adjacent two-dimensional negative Poisson's ratio cells (7), the arc-shaped rib II (11-2) of the upper two-dimensional negative Poisson's ratio cell (7) is connected to the arc-shaped rib I (11-1) of the lower two-dimensional negative Poisson's ratio cell (7), and the straight rib II (12-2) of the upper two-dimensional negative Poisson's ratio cell (7) is connected to the straight rib I (12-1) of the lower two-dimensional negative Poisson's ratio cell (7); the horizontal cell wall II (8-2) of the upper two-dimensional negative Poisson's ratio cell (7) is connected to the horizontal cell wall I (8-1) of the lower two-dimensional negative Poisson's ratio cell (7); In two adjacent two-dimensional negative Poisson's ratio cells (7), the extension wall II (9-2) of the left two-dimensional negative Poisson's ratio cell (7) is connected to the extension wall I (9-1) of the right two-dimensional negative Poisson's ratio cell (7), and the straight rib II (12-2) of the left two-dimensional negative Poisson's ratio cell (7) is connected to the straight rib I (12-1) of the right two-dimensional negative Poisson's ratio cell (7).

7. The negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling according to claim 1, characterized in that, The upper frame plate (4) and the lower frame plate (5) have the same structure, both including: a first circular ring (13) and a six-chirality structure, wherein the six-chirality structure is connected to the inner ring of the first circular ring (13).

8. The negative Poisson's ratio tubular energy-absorbing structure based on dual-mode compression-torsion coupling according to claim 7, characterized in that, The six-chiral structure includes a second ring (14) and six extension arms (15). The second ring (14) is concentric with the first ring (13). The outer ring of the second ring (14) is connected to the inner ring of the first ring (13) by six extension arms (15) arranged at an angle.

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