Double-layer multi-cell energy absorption thin-walled tube with pre-folded outer wall

Abstract

The invention relates to a double-layer multi-cell energy absorption thin-walled tube with a pre-folded outer wall. The double-layer multi-cell energy absorption thin-wall pipe comprises a thin-wall inner pipe, a thin-wall outer pipe and an inner rib plate which are arranged in a nested mode. The thin-wall inner pipe and the thin-wall outer pipe are repeatedly connected in the axial direction of the pipe through N layers of unit cell structures. Each layer of unit cell structure comprises a double-layer thin-wall outer tube and an inner square tube which is connected up and down, and an inner rib plate structure which forms an included angle is connected between the vertical center line of each side wall of the inner square tube and the double-layer thin-wall outer tube; the double-layer thin-wall outer pipe comprises a first unit wall plate and a second unit wall plate which are symmetrical in the circumferential direction of the thin-wall pipe. The first unit wall plate is defined by a double-layer first trapezoidal wall plate and double-layer parallelogram wall plates arranged on the two sides of the first trapezoidal wall plate, the second unit wall plate is a double-layer second trapezoidal wall plate arranged between the first unit wall plates, and the double-layer thin-wall outer pipe is formed by pre-folding a plurality of peak creases and valley creases. Compared with an existing thin-walled tube, the double-layer multi-cell energy absorption thin-walled tube has the advantages that the specific energy absorption is more obviously improved, the compression resistance advantage is obvious, and the application range is wider.

Description

Technical Field

[0001] This invention belongs to the field of structural mechanics technology, specifically relating to a double-layer multi-cell energy-absorbing thin-walled tube with a pre-folded outer wall. Background Technology

[0002] Thin-walled tubular structures, due to their small mass, high specific strength and stiffness, and significant energy absorption, have been widely used in industries such as automotive and aerospace, for example, in automotive crash beams, aircraft landing gear, and satellite landing gear. With the rapid development of new energy vehicles, drones, and other equipment, the demand for thin-walled structures is constantly increasing to meet the stringent requirements of impact collisions. Although traditional thin-walled tubular structures are lightweight and easy to manufacture and assemble, they face the challenge of not simultaneously meeting the requirements of low peak fracture force (PCF), high specific energy absorption (SEA), and load efficiency (CLE). Therefore, there is an urgent need to propose a design strategy for thin-walled structures to improve their impact resistance.

[0003] To improve the impact resistance of thin-walled structures, some works have introduced specific defects, such as corrugations, groove shapes, and trigger dents. Studies have shown that the mechanical properties and energy absorption of modified thin-walled tubes can be optimized through strategic defects, stabilizing the fracture mode by reducing fluctuations in initial peak force and reaction force. Nevertheless, specific energy absorption (SEA) generally remains unchanged or even decreases due to lower support levels along the creases.

[0004] Currently, filling thin-walled tubes with honeycomb structures can effectively enhance their overall strength and structural stability, creating more sites for energy absorption and providing richer deformation modes. However, this design faces challenges in preparation and processing. Precise cell molding requires advanced equipment and molds, and strict adaptation to the carrier is necessary during filling, leading to material waste, high costs, and low production efficiency. Mechanical properties also exhibit significant directional limitations. Damage resistance is weak, and repair is difficult. Thin-walled cells are prone to irreversible deformation and diffusion after overload, internal damage is difficult to detect, and repair requires specialized equipment and complex procedures, resulting in high costs and long cycles. Environmental adaptability is also poor. Metal honeycombs are susceptible to corrosion, while plastic or composite honeycombs are prone to aging. Furthermore, extreme temperatures can cause sudden changes in material properties, and the thermal expansion and contraction of the air layer between cells can lead to debonding of the honeycomb from the carrier, affecting overall stability.

[0005] Origami unit cell tubes are inspired by traditional origami art, forming three-dimensional tubular components through the regular folding of two-dimensional planar materials. This structure boasts high foldability, lightweight characteristics, and modular design potential, enabling transformation from planar to three-dimensional form, and possessing intelligent features such as self-unfolding and self-adaptation. However, origami unit cell tubes have poor impact resistance. While designing origami unit cell tubes as multi-cell structures can improve deformation stability, reduce initial peak force, and increase energy absorption efficiency in most cases, the impact resistance of this design remains unsatisfactory.

[0006] Origami-patterned tubes retain their full energy absorption capacity by maintaining material integrity. Their creases precisely guide the collapse along a predetermined path, forming plastic hinges that produce lower initial peak forces and more stable crushing compared to conventional tubes of matching dimensions. For example, patent application CN117553189A describes a biomimetic multi-cell sandwich tube structure capable of impact resistance, energy absorption, and pressure bearing. This structure includes an outer tube, a multi-cell sandwich structure, an inner tube, and the inner and outer tubes are assembled together. The multi-cell sandwich structure between the inner and outer tubes forms a multi-layered structure, composed of multiple hollow support tubes joined side-by-side. By increasing energy absorption and pressure bearing capacity through the multi-cell sandwich structure, while simultaneously reducing weight, it achieves a lightweight, high-strength tube structure. This technology is inspired by biomimicry. Based on microscopic observations of the Cybister elytra, it was discovered that its unique composite multicellular sandwich structure provides excellent resistance to axial and lateral impacts, and its bending and compressive strength is extremely stable. Therefore, by biomimetic design of the microstructure of the Cybister elytra, a lightweight, high-strength, and energy-absorbing biomimetic tube structure was obtained, with both the inner and outer tubes being circular. Furthermore, the applicant previously filed a patent application CN119435610A for a multicellular energy-absorbing thin-walled tube based on an origami structure. This design combines a thin-walled inner tube with an origami structure and a thin-walled outer tube with ribs, achieving a higher average crushing force and thus improving the structure's load stability. The origami configuration of this structure is diamond origami, with repeated connections of identical unit wall panels, achieving an optimal specific energy absorption (SEA) of approximately 20 J / g.

[0007] This application, through further innovative improvements, combines specific pre-folded patterns with multi-cell structures to obtain thin-walled tube structures with better energy absorption performance, superior impact resistance, and wider applicability. Summary of the Invention

[0008] This invention provides a double-layer multi-cell energy-absorbing thin-walled tube with a pre-folded outer wall, which combines trapezoidal origami with Miura origami. On this basis, a concave corner structure is introduced to form the origami outer wall. Compared with existing thin-walled tubes, it significantly improves the specific energy absorption (SEA) and has significant advantages in pressure resistance. It has a wider range of applications and solves the problems existing in the prior art.

[0009] This invention provides the following technical solution:

[0010] A double-layer multi-cell energy-absorbing thin-walled tube with a pre-folded outer wall includes a nested thin-walled inner tube and a thin-walled outer tube, and a plurality of inner ribs that connect the thin-walled inner tube and the thin-walled outer tube in combination. The thin-walled inner tube and the thin-walled outer tube are composed of N layers of single-cell structures that are repeatedly connected along the axial direction of the tube. The layer height h of the 2ith layer of the thin-walled inner tube is the same as that of the ith layer of the thin-walled outer tube, where 1≤i≤N.

[0011] Each unit cell structure includes a double-layer thin-walled outer tube and two inner square tubes connected at the top and bottom. An inner rib structure is connected at an angle between the vertical center line of each side wall of the two inner square tubes and the double-layer thin-walled outer tube.

[0012] The double-layer thin-walled outer tube includes a first unit wall panel symmetrically arranged along the circumference of the thin-walled tube, and a second unit wall panel symmetrically arranged between the two first unit wall panels; the first unit wall panel is formed by a double-layer first trapezoidal wall panel and a double-layer parallelogram wall panel provided on both sides of the first trapezoidal wall panel, and the second unit wall panel is formed by a double-layer second trapezoidal wall panel.

[0013] The first unit panel includes a first upper trapezoidal unit panel and a first lower trapezoidal unit panel connected along a first fold line along their short bottom edges. A first upper parallelogram unit panel is connected to the left and right sides of the first upper trapezoidal unit panel along a second fold line, and a first lower parallelogram unit panel is connected to the left and right sides of the first lower trapezoidal unit panel along a third fold line. The first upper parallelogram unit panel and the first lower parallelogram unit panel on each side are connected by a fourth fold line. A second upper parallelogram unit panel is connected to the outer side of each first upper parallelogram unit panel via a fifth fold line. Each first lower parallelogram unit panel is connected to a second lower parallelogram unit panel via a sixth fold line on its outer side; the second upper parallelogram unit panel and the second lower parallelogram unit panel on each side are connected via a seventh fold line; the second unit panel includes a second upper trapezoidal unit panel and a second lower trapezoidal unit panel connected along an eighth fold line along its long bottom edge; the second upper parallelogram unit panel is connected to the second upper trapezoidal unit panel along a ninth fold line on its left and right sides respectively; and the second lower parallelogram unit panel is connected to the second lower trapezoidal unit panel along a tenth fold line on its left and right sides respectively.

[0014] The adjacent side lengths of the inner square tube are respectively set horizontally parallel to the first crease and the eighth crease.

[0015] Furthermore, each layer of the unit cell structure includes an upper inner square tube and a lower inner square tube, the sum of the heights of the upper and lower inner square tubes being equal to the height of the double-layer thin-walled outer tube of each layer of the unit cell structure; the inner square tube sidewall corresponding to the first fold on the double-layer thin-walled outer tube is the first sidewall, and the inner square tube sidewall corresponding to the eighth fold on the double-layer thin-walled outer tube is the second sidewall; the inner rib plate structures provided on the adjacent first and second sidewalls of the inner square tube are the first rib plate structure and the second rib plate structure, respectively.

[0016] The first rib structure consists of a first group of ribs and a second group of ribs arranged at an angle, and the second rib structure consists of a third group of ribs and a fourth group of ribs arranged at an angle. The ribs on adjacent first and second sidewalls of the inner square tube are arranged parallel to each other. The first and second groups of ribs are each composed of a first upper rib and a first lower rib, and the third and fourth groups of ribs are each composed of a second upper rib and a second lower rib, respectively. One end of the first upper rib is connected to the vertical centerline of the first sidewall of the upper inner square tube, and the other end of the first upper rib is connected to the first upper parallelogram unit. The plates are connected at their diagonal points; one end of the first lower rib plate is connected to the vertical center line of the first side wall of the lower inner square tube, and the other end of the first lower rib plate is connected to the diagonal point of the first lower parallelogram unit plate; one end of the second upper rib plate is connected to the vertical center line of the second side wall of the upper inner square tube, and the other end of the second upper rib plate is connected to the diagonal point of the second upper parallelogram unit plate; one end of the second lower rib plate is connected to the vertical center line of the second side wall of the lower inner square tube, and the other end of the second lower rib plate is connected to the diagonal point of the second lower parallelogram unit plate.

[0017] Furthermore, the upper and lower inner square tubes are fixedly connected, the first upper and lower ribs are fixedly connected, and the second upper and lower ribs are fixedly connected.

[0018] Furthermore, the diagonals of the first upper parallelogram unit plate are diagonals passing through the top two sides of the first upper trapezoid unit plate; the diagonals of the first lower parallelogram unit plate are diagonals passing through the bottom two sides of the first lower trapezoid unit plate; the diagonals of the second upper parallelogram unit plate are parallel to the diagonals of the first lower parallelogram unit plate on the same side, and the diagonals of the second lower parallelogram unit plate are parallel to the diagonals of the first upper parallelogram unit plate on the same side.

[0019] Furthermore, the aforementioned double-layer multi-cell energy-absorbing thin-walled tube is integrally molded.

[0020] Furthermore, the dihedral angles of the trapezoidal slopes of the first upper trapezoidal unit plate and the first lower trapezoidal unit plate, the dihedral angles of the trapezoidal slopes of the second upper trapezoidal unit plate and the second lower trapezoidal unit plate, as well as the dihedral angles of the slopes of the first upper parallelogram unit plate and the first lower parallelogram unit plate, the second upper parallelogram unit plate, and the second lower parallelogram unit plate are all θ.

[0021] Furthermore, θ takes values ​​ranging from 48 to 80°.

[0022] Furthermore, the inner square tube is an inner square tube with a square cross-section.

[0023] Furthermore, the first, second, third, seventh, ninth, and tenth creases are all peak creases; the fourth, fifth, sixth, and eighth creases are all valley creases.

[0024] Furthermore, let the side length of the concave angle of the thin-walled outer tube formed by the parallelogram wall panel along the circumference of the double-layer multi-cell energy-absorbing thin-walled tube be *a*, the short side length *b* and the long side length *c* of the first upper trapezoidal unit plate, the short side length *l1* of the inner rib structure, and the long side length *l2* of the inner rib structure; and let the thickness of the double-layer multi-cell energy-absorbing thin-walled tube be *t*, then a = 8 - 12 mm. t = 1.2-1.4 mm, N = 2-6,

[0025] Furthermore, a = 12 mm, t = 1.4 mm, and N = 2.

[0026] Furthermore, θ is calculated from the values ​​of a, N, and H, satisfying...

[0027] Furthermore, the included angles of the thin-walled outer tubes at the corresponding first peak fold, fourth peak fold, first valley fold, and fourth valley fold on the first unit wall panel and the second unit wall panel are all 2θ.

[0028] Furthermore, by introducing a thickness gradient k, the specific energy absorption SEA can be increased by up to 65.9%. Let the thickness of the thin-walled outer tube be t1, the thickness of the inner square tube be t3, t1 / t3 = k, and the horizontal distance between the adjacent inner rib structures on the adjacent sides of the inner square tube be t2. Then t2 = 0.8-1.2 mm, k = 0.2; t2 is preferably 1.0.

[0029] The beneficial effects of this invention are:

[0030] 1. Compared to triangular, square, and other tubular structures, the double-layer multi-cell energy-absorbing thin-walled tube of this invention exhibits higher average crushing force, higher load stability, and better energy absorption characteristics. The introduction of a corresponding patterned origami-style thin-walled outer tube structure enables stable and gradual deformation during the plateau phase of the thin-walled tube structure, resulting in a continuous and stable energy absorption effect. Analysis of the structural parameters (a, N, t, etc.) of this double-layer multi-cell energy-absorbing thin-walled tube enhances the specific energy absorption of the structure; simultaneously, the introduction of a thickness gradient parameter k further improves the specific energy absorption and load efficiency of the thin-walled tube structure.

[0031] 2. The highest specific energy absorption SEA of the present invention can reach 30.4 J / g, which greatly improves the SEA compared with the prior art, resulting in better energy absorption and a wider range of applications. It can be applied in automobile crash boxes, rail train energy absorption frames, and aerospace robot landing legs. Attached Figure Description

[0032] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0033] Figure 1 This is a schematic diagram of the structure of the double-layer multi-cell energy-absorbing thin-walled tube with a pre-folded outer wall of the present invention;

[0034] Figure 2 for Figure 1 A diagram showing the creases of the double-layered thin-walled outer tube of a single-cell structure in a multicellular energy-absorbing thin-walled tube when fully expanded.

[0035] Figure 3 for Figure 1 A schematic diagram of the three-dimensional structure of a multicellular energy-absorbing thin-walled tube;

[0036] Figure 4 for Figure 3 A structural diagram from another angle;

[0037] Figure 5 for Figure 3 Another structural diagram from a different angle;

[0038] Figure 6 A schematic diagram of the compression test loading of the double-layer multi-cell energy-absorbing thin-walled tube of the present invention;

[0039] Figure 7 This is a schematic diagram of the deformation of the double-layer multi-cell energy-absorbing thin-walled tube of the present invention under uniaxial compression;

[0040] Figure 8 This study investigates the effect of the thickness of the double-layer multi-cell energy-absorbing thin-walled tube on the energy absorption effect of the multi-cell tube in this invention.

[0041] Figure 9This is a configuration diagram of the double-layer multi-cell energy-absorbing thin-walled tube of the present invention with different side lengths 'a' and different numbers of layers;

[0042] Figure 10 For the corresponding Figure 9 The trend of specific energy absorption under different side lengths 'a';

[0043] Figure 11 For the corresponding Figure 9 The trend of specific energy absorption at different levels;

[0044] Figure 12 A schematic cross-sectional view of the present invention to identify thickness parameters at different locations;

[0045] Figure 13 This study investigates the effect of the thickness gradient k of the double-layer multi-cell energy-absorbing thin-walled tube of the present invention on energy absorption.

[0046] Among them, (a) is a reference diagram of the crease of the pre-folded outer wall, (b) is a schematic diagram of the design structure of the double-layer multi-cell energy-absorbing thin-walled tube, (c) is a top view of (b), showing the connection between the inner and outer tubes of the rib plate, and (d) is a three-dimensional schematic diagram of (b).

[0047] Figure 9 (a) shows the concave angle of the double-layer multi-cell energy-absorbing thin-walled tube with different side lengths a, and (b) shows the number of layers N of the double-layer multi-cell energy-absorbing thin-walled tube.

[0048] Figure 10 (a) shows the effect of a on PCF and MCF, and (b) shows the effect of a on SEA and CLE compared to the effect of a.

[0049] Figure 11 (a) shows the effect of layer number N on PCF and MCF, and (b) shows the effect of layer number N on energy absorption SEA and CLE.

[0050] Figure 13 (a), (b), (c), and (d) show the effects of different values ​​of t on MCF, PCF, CLE, and SEA, respectively, at a fixed t value and as t increases.

[0051] In the figure, 1 is a double-layer thin-walled outer tube, 101 is the first upper trapezoidal unit plate, 102 is the first lower trapezoidal unit plate, 103 is the first upper parallelogram unit plate, 104 is the first lower parallelogram unit plate, 105 is the second upper parallelogram unit plate, 106 is the second lower parallelogram unit plate, 107 is the second upper trapezoidal unit plate, 108 is the second lower trapezoidal unit plate, 2 is an inner square tube, 201 is an upper inner square tube, 202 is a lower inner square tube, 211 is the first side wall, 212 is the second side wall, 3 is a rib plate, 31 is the first upper rib plate, 32 is the first lower rib plate, 33 is the second upper rib plate, 34 is the second lower rib plate, 41 is the first peak fold, 42 is the second peak fold, 43 is the third peak fold, 44 is the first valley fold, 45 is the second valley fold, 46 is the third valley fold, 47 is the fourth peak fold, 48 is the fourth valley fold, 49 is the fifth peak fold, and 50 is the sixth peak fold. Detailed Implementation

[0052] The present invention will be further described below with reference to specific embodiments, but the scope of protection of this application is not limited to these embodiments.

[0053] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0054] In the description of this invention, the terms “total energy absorption (EA)”, “mean crushing force (MCF)”, “specific energy absorption (SEA)”, “peak crushing force (PCF)” and “crushing force efficiency (CLE)” are primarily used to evaluate the impact resistance characteristics of thin-walled structures.

[0055] The term EA above refers to the total energy absorbed during the crushing process, which can be expressed as:

[0056]

[0057] Where d is the effective deformation displacement, which is set to 90 mm in this study. F(x) is the instantaneous crushing load.

[0058] Mean crushing force (MCF) represents the average crushing strength of a thin-walled structure, and is calculated using the following formula:

[0059] The specific energy absorbed per unit mass is a key indicator that distinguishes the energy absorption capacity of different materials and weights, and is defined as follows:

[0060]

[0061] Where M is the total mass of the structure. Obviously, the higher the SEA, the better the energy absorption capacity.

[0062] Peak breaking force (PCF) represents the maximum instantaneous breaking load within the effective compressive displacement. Considering the impact force of a vehicle, a high PCF typically leads to significant deceleration and severe injury or even death to occupants.

[0063] Crushing force efficiency (CLE) can be expressed as:

[0064]

[0065] CLE is a metric that characterizes load consistency; the higher the CLE, the better the load consistency. For an ideal energy absorber, CLE is 100%.

[0066] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0067] In order to achieve a thin-walled tube that can simultaneously meet the requirements of low peak breaking force (PCF), high specific energy absorption (SEA), load efficiency, and impact resistance, this invention designs a double-layer multi-cell energy-absorbing thin-walled tube with a pre-folded outer wall.

[0068] Specifically, see Figure 1-5 The structure of the double-layer multi-cell energy-absorbing thin-walled tube is shown. It includes a nested thin-walled inner tube, a thin-walled outer tube, and several inner ribs that connect the thin-walled inner tube and the thin-walled outer tube. The inner ribs are arranged at included angles on the four side walls of the thin-walled inner tube. Both the thin-walled inner tube and the thin-walled outer tube are composed of N layers of single-cell structures that are repeatedly connected along the longitudinal axis of the tube. The 2ith layer of single-cell structure of the thin-walled inner tube has the same layer height h as the 1st layer of single-cell structure of the thin-walled outer tube, where 1≤i≤N.

[0069] Each of the above single-cell structures includes a double-layer thin-walled outer tube 1 and two inner square tubes 2 connected at the top and bottom. Two sets of inner rib plate structures arranged at an angle are connected between the center line of each side wall of the two inner square tubes and the double-layer thin-walled outer tube. The inner rib plate structure is composed of several rib plates 3.

[0070] The above-mentioned double-layer thin-walled outer tube 1 includes a first unit wall panel arranged horizontally and symmetrically along the circumference of the thin-walled tube, and a second unit wall panel arranged symmetrically between the two first unit wall panels; the first unit wall panel is formed by a double-layer first trapezoidal wall panel and a double-layer parallelogram wall panel provided on both sides of the first trapezoidal wall panel; the second unit wall panel is formed by a double-layer second trapezoidal wall panel.

[0071] The first unit panel includes a first upper trapezoidal unit panel 101 and a first lower trapezoidal unit panel 102 connected by a first peak fold 41 along the short bottom edge. A first upper parallelogram unit panel 103 is connected to the left and right sides of the first upper trapezoidal unit panel along a second peak fold 42, and a first lower parallelogram unit panel 104 is connected to the left and right sides of the first lower trapezoidal unit panel 102 along a third peak fold 43. The first upper parallelogram unit panel and the first lower parallelogram unit panel on each side are connected by a first valley fold 44. A second upper parallelogram unit panel 105 is connected to the outside of each first upper parallelogram unit panel by a second valley fold 45. The outer side of the parallelogram unit plate is connected to a second lower parallelogram unit plate 106 via a third valley fold 46; the second upper parallelogram unit plate 105 and the second lower parallelogram unit plate 106 on each side are connected via a fourth peak fold 47; the second unit wall plate includes a second upper trapezoidal unit plate 107 and a second lower trapezoidal unit plate 108 connected along the fourth valley fold 48 along the long bottom edge, the second upper parallelogram unit plate 105 is connected to the left and right sides of the second upper trapezoidal unit plate 107 via a fifth peak fold 49 respectively, and the second lower parallelogram unit plate 106 is connected to the left and right sides of the second lower trapezoidal unit plate 108 via a sixth peak fold 50 respectively.

[0072] The adjacent side lengths of the inner square tube are horizontally parallel to the first peak fold 41 and the fourth valley fold 48, respectively. The cross-section of the inner square tube is square.

[0073] The inner square tube includes an upper inner square tube 201 and a lower inner square tube 202, which correspond to the upper and lower layers of the double-layer thin-walled outer tube, respectively. The inner square tube sidewall corresponding to the first peak fold 41 is the first sidewall 211, and the inner square tube sidewall corresponding to the fourth valley fold 47 is the second sidewall 212. The inner rib plate structures provided on the first and second sidewalls are the first rib plate structure and the second rib plate structure, respectively. The first rib plate structure is composed of a first group of ribs and a second group of ribs arranged at an angle, and the second rib plate structure is composed of a third group of ribs and a fourth group of ribs arranged at an angle. The first and second groups of ribs are each composed of a first upper rib plate 31 and a first lower rib plate 32, respectively, and the third and fourth groups of ribs are each composed of a second upper rib plate 33 and a second lower rib plate 34, respectively. One end of the first upper rib plate 31 is connected to the center line of the first sidewall 211 of the upper inner square tube 201. One end of the upper rib 31 is connected to the diagonal of the first upper parallelogram unit plate 103; one end of the first lower rib 32 is connected to the center line of the first side wall of the lower inner square tube 202, and the other end of the first lower rib 32 is connected to the diagonal of the first lower parallelogram unit plate 104; one end of the second upper rib 33 is connected to the center line of the second side wall 212 of the upper inner square tube 201, and the other end of the second upper rib 33 is connected to the diagonal of the second upper parallelogram unit plate 105; one end of the second lower rib is connected to the center line of the second side wall of the lower inner square tube 202, and the other end of the second lower rib is connected to the diagonal of the second lower parallelogram unit plate 106.

[0074] The diagonal of the first upper parallelogram unit plate 103, which is connected to the other end of the first upper rib plate 31, is the line connecting the intersection of the first valley fold 44 and the second valley fold 45 on the same side of the single cell structure with the top of the second peak fold 42. The diagonal of the first lower parallelogram unit plate 104, which is connected to the other end of the first lower rib plate 32, is the line connecting the intersection of the first valley fold 44 and the second valley fold 45 on the same side of the single cell structure with the bottom of the third peak fold 43. The diagonal of the second upper parallelogram unit plate 105 is parallel to the aforementioned diagonal of the first lower parallelogram unit plate 104 on the same side, and the diagonal of the second lower parallelogram unit plate 106 is parallel to the aforementioned diagonal of the first upper parallelogram unit plate 103 on the same side.

[0075] The dihedral angles of the upper and lower trapezoidal inclined surfaces of the first and second unit wall panels are both θ, that is, the included angles of the thin-walled outer tubes at the corresponding first peak fold, fourth peak fold, first valley fold, and fourth valley fold on the first and second unit wall panels are all 2θ.

[0076] like Figure 1In section (b), the side length of the concave angle of the thin-walled outer tube formed by the parallelogram wall plate along the circumference of the thin-walled outer tube is a, the total height of the thin-walled tube is H, the number of thin-walled tube layers is N, and the thickness of the inner and outer tubes is uniformly t. The value of θ can be found to be in the range of 48°-80°; the short side length b and long side length c of the first upper trapezoidal unit plate, the short side length l1 of the inner rib plate 3, and the long side length l2 of the inner rib plate satisfy: a = 8-12mm.

[0077] t = 1.2-1.4 mm, N = 2-6.

[0078] Furthermore, introducing a thickness gradient k, let the thickness of the thin-walled outer tube be t1, the thickness of the inner square tube be t3, t1 / t3 = k, and the horizontal distance between two adjacent ribs 3 on adjacent sides of the inner square tube be t2. Then, the following conditions are met: t2 = 0.6 - 1.2 mm, k = 0.2 - 1.0. At the same t2, the smaller k is, the greater the specific energy absorption; that is, at the same t2, k is preferably 0.2.

[0079] The following will provide a detailed description of the double-layer multi-cell energy-absorbing thin-walled tube with a pre-folded outer wall provided by the present invention through specific embodiments.

[0080] Example 1

[0081] In this embodiment, the total layer height of the double-layer thin-walled outer tube, with each layer being a single-cell structure, is H = 90 mm, N = 4, t = 1.0 mm, and a = 16 mm.

[0082] See Figure 6 , 7 This is a schematic diagram of the compression test loading and deformation under uniaxial compression of the present invention. Figure 6 The middle part is a reference diagram of the compression test loading of the test specimen by the upper and lower pressure plates of the testing machine. The test adopts the displacement loading mode and compresses the specimen at a speed of 1 mm / min. Since different cross-sectional structures will significantly affect the energy absorption capacity and load-bearing performance of the present invention, the performance of the present invention in terms of compression resistance and energy absorption can be effectively tested through this loading device. Figure 7 In this context, the percentage represents the displacement generated under axial load. It can be seen that when the double-layer multi-cell energy-absorbing thin-walled tube provided by this invention is subjected to external force, it dissipates energy through pre-folded outer wall deformation and tensile deformation, resulting in stable and gradual deformation of the overall structure under crease-induced deformation.

[0083] I. Investigating the effect of thin-walled tube thickness on the energy absorption performance of multi-cell energy-absorbing thin-walled tubes:

[0084] See Figure 8The influence of the thickness of the thin-walled tube in this invention on the energy absorption effect of the multicell tube was investigated. In the figure, thickness t represents the uniform thickness of the thin-walled inner tube, thin-walled outer tube, and inner rib. The study concludes that thickness has a significant impact on the energy absorption of the multicell tube, producing more and more stable deformation wrinkles, and substantially increasing the plateau force and various energy absorption indicators. Figure 8 Results (a) and (b) show that when t varies within the range of 0.6 mm to 1.4 mm, the peak breaking force (PCF) and average breaking force (MCF) increase with increasing thickness, as does the specific energy absorption (SEA) and the energy absorption capacity (CLE), while the CLE is not significantly affected by thickness. A thickness t of 1.4 mm is preferred for multicellular energy-absorbing thin-walled tubes, as it is beneficial to energy absorption performance.

[0085] II. Investigating the effects of different side lengths 'a' of the concave angle and different numbers of layers 'N' on the energy absorption effect of the double-layered multi-celled energy-absorbing thin-walled tube.

[0086] See Figures 9-11 ,Depend on Figure 10 As shown in (a), with other parameters remaining constant, as the concave corner side length a of the double-layer multi-cell energy-absorbing thin-walled tube increases, both the peak breaking force PCF and the average breaking force MCF show a gradual increasing trend. Moreover, when a is 14 mm and 16 mm, the change in MCF is not obvious. Figure 10 The results in (b) show that the specific energy absorption (SEA) first increases and then decreases with the side length *a* of the cross section, indicating that the structure will have a higher specific energy absorption when *a* = 12 mm. Based on the optimal *a*, see... Figure 11 The results showed that the SEA (Series Aspect Ratio) tends to decrease as the number of layers N increases.

[0087] III. Investigating the effect of the thickness gradient k of a double-layered multicellular energy-absorbing thin-walled tube on energy absorption.

[0088] Introducing a thickness gradient k, such as Figure 12 , 13 As shown, the weight is kept consistent with the uniform thickness of the tube. The thickness t1 of the double-layer thin-walled outer tube is proportional to the thickness t3 of the inner square tube, k. If t2 remains constant, the structural mass remains unchanged (t2 is the horizontal distance between two adjacent sets of inner ribs on the adjacent sidewalls of the inner square tube, see [reference]). Figure 13 , Figure 13 In the middle horizontal axis (t, i.e. t2), introducing a thickness gradient k can further improve the specific energy absorption and load efficiency of the structure. The specific energy absorption can be increased by up to 65.9%. Under the same t2, the smaller k is, the higher the specific energy absorption SEA is generally. Therefore, k is preferably 0.2.

[0089] When a double-layer multicellular energy-absorbing thin-walled tube satisfies the following conditions: a = 12 mm, t2 = 1.0 mm, k = 0.2, and N = 4, the SEA can reach as high as 30.4 J / g. At the same time, the MCF reaches 170 kN, the PCF reaches 211 kN, and the CLE exceeds 80%.

[0090] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0091] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A double-layered multi-cell energy-absorbing thin-walled tube with pre-folded outer wall, comprising a thin-walled inner tube, a thin-walled outer tube arranged in a nested manner, and a plurality of inner rib plates for compositely connecting the thin-walled inner tube and the thin-walled outer tube, characterized in that, The thin-walled inner tube and the thin-walled outer tube are composed of N layers of unit cells connected in sequence along the axial direction of the tube, and the 2i layer of the thin-walled inner tube has the same layer height h as the i layer of the thin-walled outer tube, wherein 1≤i≤N; Each layer of unit cell structure includes a double-layer thin-walled outer tube and two inner square tubes connected above and below, and an inner rib plate structure is arranged between the vertical center lines of the side walls of the two inner square tubes and the double-layer thin-walled outer tube; The double-layer thin-walled outer tube includes first unit wall plates symmetrically arranged along the circumference of the thin-walled tube, and a second unit wall plate symmetrically arranged between the two first unit wall plates; the first unit wall plate is surrounded by a double-layer first trapezoidal wall plate and a double-layer parallelogram wall plate arranged on both sides of the first trapezoidal wall plate, and the second unit wall plate is surrounded by a double-layer second trapezoidal wall plate; The first unit wall plate includes a first upper trapezoidal unit plate and a first lower trapezoidal unit plate connected along a first fold line, a first upper parallelogram unit plate connected along a second fold line on the left and right sides of the first upper trapezoidal unit plate, and a first lower parallelogram unit plate connected along a third fold line on the left and right sides of the first lower trapezoidal unit plate; the first upper parallelogram unit plate and the first lower parallelogram unit plate on each side are connected by a fourth fold line; a second upper parallelogram unit plate is connected to the outside of each first upper parallelogram unit plate by a fifth fold line, and a second lower parallelogram unit plate is connected to the outside of each first lower parallelogram unit plate by a sixth fold line; the second upper parallelogram unit plate and the second lower parallelogram unit plate on each side are connected by a seventh fold line; the second unit wall plate includes a second upper trapezoidal unit plate and a second lower trapezoidal unit plate connected along an eighth fold line, the second upper parallelogram unit plate connected along a ninth fold line on the left and right sides of the second upper trapezoidal unit plate, and the second lower parallelogram unit plate connected along a tenth fold line on the left and right sides of the second lower trapezoidal unit plate; The adjacent side lengths of the inner square tube are arranged horizontally parallel to the first fold line and the eighth fold line.

2. The double-walled multi-cell energy absorbing thin-walled tube with pre- folded outer wall of claim 1, wherein, The inner square tube of each layer of unit cell structure includes an upper inner square tube and a lower inner square tube, and the sum of the heights of the upper and lower inner square tubes is equal to the height of the double-layer thin-walled outer tube of each layer of unit cell structure; the side wall of the inner square tube corresponding to the first fold line of the double-layer thin-walled outer tube is a first side wall, and the side wall of the inner square tube corresponding to the eighth fold line of the double-layer thin-walled outer tube is a second side wall; the inner rib plate structures arranged on the adjacent first and second side walls of the inner square tube are a first rib plate structure and a second rib plate structure, respectively. The first rib plate structure is composed of a first group of rib plates and a second group of rib plates arranged at an angle, and the second rib plate structure is composed of a third group of rib plates and a fourth group of rib plates arranged at an angle; the rib plates on the adjacent first and second side walls of the inner square tube are arranged in parallel; the first group and the second group of rib plates are each composed of a first upper rib plate and a first lower rib plate, and the third group and the fourth group of rib plates are each composed of a second upper rib plate and a second lower rib plate; one end of the first upper rib plate is connected to the vertical center line of the first side wall of the upper inner square tube, and the other end of the first upper rib plate is connected to the diagonal line of the first upper parallelogram unit plate; one end of the first lower rib plate is connected to the vertical center line of the first side wall of the lower inner square tube, and the other end of the first lower rib plate is connected to the diagonal line of the first lower parallelogram unit plate; one end of the second upper rib plate is connected to the vertical center line of the second side wall of the upper inner square tube, and the other end of the second upper rib plate is connected to the diagonal line of the second upper parallelogram unit plate; one end of the second lower rib plate is connected to the vertical center line of the second side wall of the lower inner square tube, and the other end of the second lower rib plate is connected to the diagonal line of the second lower parallelogram unit plate.

3. The double-walled multi-cell energy absorbing thin-walled tube with pre- folded outer wall of claim 2, wherein, The diagonal line of the first upper parallelogram unit plate is a diagonal line passing through the two side top ends of the first upper trapezoidal unit plate; the diagonal line of the first lower parallelogram unit plate is a diagonal line passing through the two side bottom ends of the first lower trapezoidal unit plate; the diagonal line of the second upper parallelogram unit plate is parallel to the diagonal line of the first lower parallelogram unit plate on the same side, and the diagonal line of the second lower parallelogram unit plate is parallel to the diagonal line of the first upper parallelogram unit plate on the same side.

4. The double-walled, multi-cellular, energy-absorbing thin-walled tube with pre-folded outer wall of claim 1, wherein, The dihedral angle of the trapezoidal slope of the first upper trapezoidal unit plate and the first lower trapezoidal unit plate, the dihedral angle of the trapezoidal slope of the second upper trapezoidal unit plate and the second lower trapezoidal unit plate, and the dihedral angle of the slope of the first upper parallelogram unit plate and the first lower parallelogram unit plate, the dihedral angle of the slope of the second upper parallelogram unit plate and the second lower parallelogram unit plate are all θ.

5. The double-walled, multi-cellular, energy-absorbing thin-walled tube with pre-folded outer wall of claim 4, wherein, θ is in the range of 48°-80°.

6. The double-walled, multi-cellular, energy-absorbing thin-walled tube with pre-folded outer wall of claim 1, wherein, The inner square tube is a square cross-section inner square tube.

7. The double-walled, multi-cellular, energy-absorbing thin-walled tube with pre-folded outer wall of claim 1, wherein, The first crease, the second crease, the third crease, the seventh crease, the ninth crease, and the tenth crease are all peak creases; the fourth crease, the fifth crease, the sixth crease, and the eighth crease are all valley creases.

8. The double-walled, multi-cellular, energy-absorbing thin-walled tube with pre-folded outer wall of claim 1, wherein, Let the concave angle side length of the thin-walled outer tube formed by the parallelogram wall plate along the circumference of the double-layer multi-cell energy-absorbing thin-walled tube be a, the short side length b and the long side length c of the first upper trapezoidal unit plate, the short side length l1 of the inner rib plate structure, and the long side length l2 of the inner rib plate structure; the thickness of the double-layer multi-cell energy-absorbing thin-walled tube is t, then: a = 8 mm - 12 mm, t = 1.2 - 1.4 mm, N = 2 - 6, 9. The double-walled, multi-cellular, energy-absorbing thin-walled tube with pre-folded outer wall of claim 8, wherein, a = 12 mm, t = 1.4 mm, N = 2.

10. The double-walled, multi-cellular, energy-absorbing thin-walled tube with pre- folded outer wall according to any one of claims 1 to 9, characterized in that Let the thickness of the thin-walled outer tube be t1, the thickness of the inner square tube be t3, t1 / t3 = k, and the horizontal distance between the inner rib plate structures adjacent to each other on the adjacent side length of the inner square tube be t2, then t2 = 0.8-1.2 mm, k = 0.2.

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