Energy absorbing structure based on nested corrugated twist metamaterials

Abstract

This invention discloses an energy-absorbing structure based on nested corrugated compression-torsion metamaterials, belonging to the field of metamaterial vibration reduction and impact resistance technology. The invention comprises an energy-absorbing core layer disposed between an upper panel and a lower panel arranged coaxially at intervals. The energy-absorbing core layer includes a first energy-absorbing cell and multiple second energy-absorbing cells arranged in a circular array based on the first energy-absorbing cell. The first and second energy-absorbing cells have identical structures, each including a first outer unit cell, a first inner unit cell, a second outer unit cell, and a second inner unit cell. The first inner unit cell is coaxially disposed inside the first outer unit cell, and the second inner unit cell is coaxially disposed inside the second outer unit cell. The first and second outer unit cells are mirror images of each other along the height direction. The first and second inner unit cells are also mirror images of each other along the height direction. This invention can achieve stable graded crushing energy absorption under compressive loads and can reduce the displacement response and stress concentration of the lower panel through the coordinated deformation of the multi-cell array under explosive impact loads.

Description

Technical Field

[0001] This invention relates to the field of metamaterial vibration reduction and impact resistance technology, specifically to an energy-absorbing structure based on nested corrugated compression-torsion metamaterials. Background Technology

[0002] Energy-absorbing metamaterials are a class of structural materials whose equivalent mechanical response is controlled through artificial configuration design. Their energy dissipation capacity mainly originates from the buckling evolution, folding and crushing, plastic hinge formation, and multi-level force transmission paths of structural units during loading, rather than simply depending on the strength or toughness of the matrix material itself. In the field of impact protection, such structures are usually designed as sandwich core layers to absorb external input energy within a limited installation space and reduce displacement, velocity, and stress response on the protective back side.

[0003] For compression- and explosion-proof sandwich structures, their working environment exhibits significant multi-condition coupling characteristics. On the one hand, under quasi-static or low-velocity compressive loads, the core layer needs a stable crushing plateau and a long effective deformation stroke to avoid rapid attenuation of load-bearing capacity due to local buckling concentration. On the other hand, under explosive impact loads, the load duration is short, the peak value is high, and the spatial distribution is uneven. The structure not only needs to rapidly dissipate the input energy but also needs to effectively diffuse the local impact load between the panel and the core layer to suppress excessive transient displacement and local stress concentration on the back blast surface. Therefore, simply pursuing high initial stiffness or high peak load-bearing capacity cannot meet the comprehensive requirements of compression energy absorption and explosion protection.

[0004] Existing sandwich energy-absorbing structures still have several shortcomings in practical applications. Some thin-walled or multi-cell structures are prone to local collapse dominated by a single buckling band during compression, resulting in uncontrollable deformation modes, large fluctuations in platform loads, or insufficient effective energy absorption stroke. Although some structures can improve load-bearing capacity, they tend to directly transfer higher loads to the back plate under impact loads, making it difficult to effectively reduce the displacement response and stress concentration on the back explosion surface. Furthermore, some sandwich structures rely on welding, adhesive bonding, or mechanical connections to achieve the face-core combination. Under transient loads such as explosive impacts, the face-core interface is prone to debonding, cracking, or connection failure, weakening the overall force transmission continuity and energy dissipation stability of the structure.

[0005] Therefore, how to enable sandwich energy-absorbing structures to simultaneously possess stable compressive deformation, graded energy dissipation, impact load diffusion, and integrated face-core anti-failure capability is a pressing technical problem to be solved in the design of compression and explosion-proof protective structures. To this end, it is necessary to propose an energy-absorbing structure capable of inducing controllable buckling and synergistic crushing through geometric configuration, so as to achieve high energy absorption efficiency and low back-burst surface deformation response under both axial compression and explosive impact conditions. Summary of the Invention

[0006] This invention provides an energy-absorbing structure based on nested corrugated compressive-torsional metamaterials. The structure forms a double-layered mirrored reverse torsion, coaxial nesting, and integrally connected energy-absorbing structure through a first outer unit cell, a first inner unit cell, a second outer unit cell, and a second inner unit cell. Under compressive loads, it can achieve stable graded crushing energy absorption. Under explosive impact loads, it can reduce the displacement response and stress concentration of the lower panel (back explosion surface) through the coordinated deformation of the multi-cell array.

[0007] The technical solution of this invention is:

[0008] An energy-absorbing structure based on nested corrugated compression-torsion metamaterial includes an upper panel 8, a lower panel 9, and an energy-absorbing core layer disposed between the upper panel 8 and the lower panel 9 arranged coaxially at intervals.

[0009] The energy-absorbing core layer includes a first energy-absorbing cell and a plurality of second energy-absorbing cells arranged in a circular array based on the first energy-absorbing cell. The first energy-absorbing cell and the second energy-absorbing cell have the same structure, each including a first outer unit cell 4, a first inner unit cell 5, a second outer unit cell 6, and a second inner unit cell 7.

[0010] The first inner cell 5 is coaxially disposed inside the first outer cell 4 and a first gap space is formed between the first inner cell 5 and the first outer cell 4. The second inner cell 7 is coaxially disposed inside the second outer cell 6 and a second gap space is formed between the second inner cell 7 and the second outer cell 6, which is connected to the first gap space.

[0011] One end of the first outer unit cell 4 and one end of the first inner unit cell 5 are integrally formed and connected to the side of the lower panel 9 near the upper panel 8. One end of the second outer unit cell 6 and one end of the second inner unit cell 7 are integrally formed and connected to the side of the upper panel 8 near the lower panel 9. The first outer unit cell 4 and the second outer unit cell 6 are arranged in a mirror image along the height direction, and the other end of the first outer unit cell 4 and the other end of the second outer unit cell 6 are integrally formed and connected at the mirror interface. The first inner unit cell 5 and the second inner unit cell 7 are arranged in a mirror image along the height direction, and the other end of the first inner unit cell 5 and the other end of the second inner unit cell 7 are integrally formed and connected at the mirror interface.

[0012] Furthermore, the first outer unit cell 4, the first inner unit cell 5, the second outer unit cell 6, and the second inner unit cell 7 are all corrugated twisted thin-walled structures arranged along the height direction, and their cross-sections are all continuous corrugated closed sections.

[0013] The continuous corrugated closed section is formed by the inner boundary curve and the outer boundary curve. The inner boundary curve is formed equidistantly from the reference curve inwards, and the outer boundary curve is formed equidistantly from the reference curve outwards. The distances between the inner boundary curve, the outer boundary curve and the reference curve are equal.

[0014] The reference curve is formed by connecting multiple Bézier curves 1 one after another. Each Bézier curve 1 has an outward convex peak and an inward concave valley. The multiple Bézier curves 1 use a regular polygon 2 and the inscribed circle 3 of the regular polygon 2 as the configuration reference. The two endpoints of each side of the regular polygon 2 are taken as the first endpoint and the second endpoint. The first endpoint of each side of the regular polygon 2 is the endpoint of the corresponding Bézier curve 1 that is closer to the outward convex peak, and the second endpoint of each side of the regular polygon 2 is the endpoint of the corresponding Bézier curve 1 that is closer to the inward concave valley.

[0015] Furthermore, the Bézier curve 1 is a cubic Bézier curve. The control points for the convex peak and the concave valley are determined as follows: the sides of the regular polygon 2 are divided into three equal parts from the first endpoint to the second endpoint to form two perpendicular lines perpendicular to the corresponding sides: a first perpendicular line and a second perpendicular line. The first perpendicular line is closer to the first endpoint. The control point of the convex peak is located on the first perpendicular line, and the control point of the concave valley is located on the second perpendicular line. The perpendicular distance L between the control points of the convex peak and the concave valley and the corresponding sides is equal.

[0016] Furthermore, the value of L ranges from 2mm to 10mm.

[0017] Furthermore, the radius of the inscribed circle 3 of the first outer unit cell 4 is 20 mm to 100 mm, and the radius of the inscribed circle 3 of the first inner unit cell 5 is 0.4 to 0.8 times the radius of the inscribed circle 3 of the first outer unit cell 4.

[0018] Furthermore, the distance between the center of each second energy-absorbing cell and the center of the first energy-absorbing cell is equal, and the distance between the center of the second energy-absorbing cell and the center of the first energy-absorbing cell is 1.1 to 1.8 times the radius of the inscribed circle 3 of the first outer unit cell 4.

[0019] Furthermore, the first outer unit cell 4, the first inner unit cell 5, the second outer unit cell 6, and the second inner unit cell 7 have the same single-layer height, which is 10mm to 60mm, and the same wall thickness, which is 0.3mm to 3mm.

[0020] Furthermore, the cylinder walls of the first outer cell 4 and the first inner cell 5 are both twisted and extended along the height direction, and the cylinder walls of the second outer cell 6 and the second inner cell 7 are both twisted and extended along the height direction.

[0021] Furthermore, the torsion angle of the upper end cross section of the first outer unit cell 4 and the first inner unit cell 5 relative to the lower end cross section is 10° to 60°; the torsion angles of the first outer unit cell 4 and the first inner unit cell 5 are equal in magnitude and in the same direction; the torsion angles of the second outer unit cell 6 and the second inner unit cell 7 are equal in magnitude and in the same direction, the torsion angles of the second outer unit cell 6 and the first outer unit cell 4 are equal in magnitude and opposite in direction, and the torsion angles of the second inner unit cell 7 and the first inner unit cell 5 are equal in magnitude and opposite in direction.

[0022] The beneficial effects of this invention are:

[0023] 1. The present invention adopts an integral structure of the upper panel, lower panel and energy-absorbing core layer, so that the first outer unit cell, the first inner unit cell, the second outer unit cell and the second inner unit cell form a continuous integral structure with the panel, avoiding the debonding, cracking and connection failure problems that are easily caused by traditional welding, gluing or mechanical connection methods under impact load, and improving the overall load-bearing stability and impact resistance reliability of the sandwich energy-absorbing structure.

[0024] 2. The present invention arranges the first outer cell and the second outer cell in a mirror-image reverse twisting arrangement along the height direction, and the first inner cell and the second inner cell in a mirror-image reverse twisting arrangement along the height direction, so that the upper and lower cell layers generate a twisting and folding trend in opposite directions during compression or explosive impact, thereby suppressing the overall rotational instability and eccentric collapse that are prone to occur in unidirectional torsion thin-walled structures, and improving the stability of the structure during the crushing process.

[0025] 3. The present invention adopts a coaxial nested cell structure with an inner and outer unit cell, and forms a communicating gap space between the outer unit cell and the inner unit cell, so that the inner and outer unit cells can undergo asynchronous buckling, torsion folding and graded crushing during loading, thereby extending the effective energy absorption stroke and improving the impact energy dissipation capacity.

[0026] 4. Each unit cell of the present invention adopts a continuous corrugated closed section composed of Bézier curves, which can form a continuous undulating deformation-inducing region in the circumference of the thin-walled structure. Compared with straight-edged polygonal cylinders, ordinary cylinders or single corrugated cylinder structures, it can reduce local stress concentration and guide the wall surface to produce more stable bending, folding and crushing deformation.

[0027] 5. The present invention arranges multiple energy-absorbing cells in a circular array around the first energy-absorbing cell, which can transfer and disperse local impact loads to multiple cells. Through the coordinated deformation of multiple cells, the displacement response, velocity response and stress concentration of the lower panel are reduced, thereby improving the ability of the structure to suppress the deformation of the back surface under explosive impact or strong impact load.

[0028] 6. The structural performance of the present invention has strong design flexibility. By adjusting geometric parameters such as the control distance of the Bézier curve, cell torsion angle, inner and outer unit cell size ratio, wall thickness, cell height and array number, the trigger load, crushing mode, energy absorption stroke and explosion-proof response of the structure can be controlled to adapt to different impact protection and energy absorption vibration reduction application scenarios. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0030] Figure 2 An exploded view of the energy-absorbing structure of the present invention provided according to an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the configuration of the continuous corrugated closed section of the present invention;

[0032] Figure 4 This is a top view of the structure of the present invention, which is a plurality of second energy-absorbing cells arranged in a circular array based on the first energy-absorbing cells;

[0033] Figure 5 This is a schematic diagram of the overall structure of the first comparison structure;

[0034] Figure 6 This is a schematic diagram of the overall structure of the second comparative structure;

[0035] Figure 7 This is a schematic diagram of the overall structure of the third comparison structure;

[0036] Figure 8 This is a comparison diagram of the force-displacement curves and specific energy absorption-displacement curves of the energy-absorbing structure of the present invention and the first comparative structure under axial compression conditions; wherein, Figure 8 (a) is a comparison diagram of the force-displacement curves of the energy-absorbing structure of the present invention and the first comparative structure under axial compression conditions; Figure 8 (b) is a comparison diagram of the specific energy absorption-displacement curves of the energy-absorbing structure of the present invention and the first comparative structure under axial compression conditions;

[0037] Figure 9 This is a comparison diagram of the displacement response of the upper and lower panels of the energy-absorbing structure of the present invention and the first comparative structure under an explosive impact condition; wherein, Figure 9 (a) is a comparison diagram of the upper panel displacement response of the energy-absorbing structure of the present invention and the first comparative structure under the explosive impact condition; Figure 9 (b) is a comparison diagram of the displacement response of the lower panel of the energy-absorbing structure of the present invention and the first comparative structure under the explosive impact condition;

[0038] Figure 10 This is a comparison diagram of the total energy absorption of the energy-absorbing structure of the present invention and the first comparative structure under explosive impact conditions;

[0039] Figure 11 This is a comparison diagram of the force-displacement curves and specific energy absorption-displacement curves of the energy-absorbing structure of the present invention and the second comparative structure under axial compression conditions; wherein, Figure 11 (a) is a comparison diagram of the force-displacement curves of the energy-absorbing structure of the present invention and the second comparative structure under axial compression conditions; Figure 11 (b) is a comparison diagram of the specific energy absorption-displacement curves of the energy-absorbing structure of the present invention and the second comparative structure under axial compression conditions;

[0040] Figure 12 This is a comparison diagram of the displacement response of the upper and lower panels of the energy-absorbing structure of the present invention and the second comparative structure under an explosive impact condition; wherein, Figure 12 (a) is a comparison diagram of the upper panel displacement response of the energy-absorbing structure of the present invention and the second comparative structure under the explosive impact condition; Figure 12 (b) is a comparison diagram of the displacement response of the lower panel of the energy-absorbing structure of the present invention and the second comparative structure under the condition of explosion impact;

[0041] Figure 13 This is a comparison diagram of the total energy absorption of the energy-absorbing structure of the present invention and the second comparative structure under explosive impact conditions;

[0042] Figure 14 This is a comparison diagram of the force-displacement curves and specific energy absorption-displacement curves of the energy-absorbing structure of this invention and the third comparative structure under axial compression conditions; wherein, Figure 14 (a) is a comparison diagram of the force-displacement curves of the energy-absorbing structure of the present invention and the third comparative structure under axial compression conditions; Figure 14 (b) is a comparison diagram of the specific energy absorption-displacement curves of the energy-absorbing structure of the present invention and the third comparative structure under axial compression conditions;

[0043] Figure 15 This is a comparison diagram of the displacement response of the upper and lower panels of the energy-absorbing structure of this invention and the third comparative structure under an explosive impact condition; wherein, Figure 15 (a) is a comparison diagram of the upper panel displacement response of the energy-absorbing structure of the present invention and the third comparative structure under the explosive impact condition; Figure 15 (b) is a comparison diagram of the displacement response of the lower panel of the energy-absorbing structure of the present invention and the third comparative structure under the explosive impact condition;

[0044] Figure 16 This is a comparison diagram of the total energy absorption of the energy-absorbing structure of the present invention and the third comparative structure under explosive impact conditions;

[0045] The labels in the figure are as follows: 1-Bezier curve, 2-regular polygon, 3-inscribed circle, 4-first outer unit cell, 5-first inner unit cell, 6-second outer unit cell, 7-second inner unit cell, 8-top panel, 9-bottom panel. Detailed Implementation

[0046] 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.

[0047] Example 1: As Figures 1 to 4As shown, the energy-absorbing structure based on nested corrugated compression-torsion metamaterial includes an upper panel 8, a lower panel 9, and an energy-absorbing core layer disposed between the upper panel 8 and the lower panel 9 arranged coaxially at intervals.

[0048] The energy-absorbing core layer includes a first energy-absorbing cell and a plurality of second energy-absorbing cells arranged in a circular array based on the first energy-absorbing cell. The first energy-absorbing cell and the second energy-absorbing cell have the same structure, each including a first outer unit cell 4, a first inner unit cell 5, a second outer unit cell 6, and a second inner unit cell 7.

[0049] The first inner cell 5 is coaxially disposed inside the first outer cell 4 and a first gap space is formed between the first inner cell 5 and the first outer cell 4. The second inner cell 7 is coaxially disposed inside the second outer cell 6 and a second gap space is formed between the second inner cell 7 and the second outer cell 6, which is connected to the first gap space.

[0050] One end of the first outer unit cell 4 and one end of the first inner unit cell 5 are integrally formed and connected to the side of the lower panel 9 near the upper panel 8. One end of the second outer unit cell 6 and one end of the second inner unit cell 7 are integrally formed and connected to the side of the upper panel 8 near the lower panel 9. The first outer unit cell 4 and the second outer unit cell 6 are arranged in a mirror image along the height direction, and the other end of the first outer unit cell 4 and the other end of the second outer unit cell 6 are integrally formed and connected at the mirror interface. The first inner unit cell 5 and the second inner unit cell 7 are arranged in a mirror image along the height direction, and the other end of the first inner unit cell 5 and the other end of the second inner unit cell 7 are integrally formed and connected at the mirror interface.

[0051] As can be seen from the above scheme, in this invention, the first outer cell 4 and the second outer cell 6, and the first inner cell 5 and the second inner cell 7 are integrally connected without a middle panel. The lower ends of the first outer cell 4 and the first inner cell 5 are integrally connected to the upper end of the lower panel 9, and the upper ends of the second outer cell 6 and the second inner cell 7 are integrally connected to the lower end of the upper panel 8. Through the above design, the energy-absorbing structure of this invention is a continuous, integrated, double-layer mirror force transmission structure, so that the upper panel 8, the lower panel 9, and the energy-absorbing core layer form an integral and cooperative load-bearing structure. Furthermore, there are no radial direct connectors between the first outer cell 4 and the first inner cell 5, and between the second outer cell 6 and the second inner cell 7. Instead, they are designed to communicate with the first gap space and the second gap space. This design allows the inner and outer cells to undergo local buckling, torsional folding, and crushing deformation respectively during loading.

[0052] Furthermore, the first outer unit cell 4, the first inner unit cell 5, the second outer unit cell 6, and the second inner unit cell 7 are all corrugated twisted thin-walled structures arranged along the height direction, and their cross-sections are all continuous corrugated closed sections.

[0053] The continuous corrugated closed section is formed by the inner boundary curve and the outer boundary curve. The inner boundary curve is formed equidistantly from the reference curve inwards, and the outer boundary curve is formed equidistantly from the reference curve outwards. The distances between the inner boundary curve, the outer boundary curve and the reference curve are equal.

[0054] The reference curve is formed by connecting multiple Bézier curves 1 one after another. Each Bézier curve 1 has an outward convex peak and an inward concave valley (that is, the reference curve is formed by connecting multiple Bézier curves 1 to form an alternating outward convex peak and inward concave valley along the circumference). The multiple Bézier curves 1 use a regular polygon 2 and the inscribed circle 3 of the regular polygon 2 as the configuration reference. The number of sides of the regular polygon 2 is the same as the number of Bézier curves 1 that form the reference curve. The two endpoints of each side of the regular polygon 2 are taken as the first endpoint and the second endpoint. The first endpoint of each side of the regular polygon 2 is the endpoint of the corresponding Bézier curve 1 that is closer to the outward convex peak, and the second endpoint of each side of the regular polygon 2 is the endpoint of the corresponding Bézier curve 1 that is closer to the inward concave valley.

[0055] The Bézier curve 1 is a cubic Bézier curve. The control points for the convex peak and the concave valley are determined as follows: the sides of the regular polygon 2 are divided into three equal parts from the first endpoint to the second endpoint to form two perpendicular lines perpendicular to the corresponding sides: the first perpendicular line and the second perpendicular line. The first perpendicular line is closer to the first endpoint. The control point of the convex peak is located on the first perpendicular line, and the control point of the concave valley is located on the second perpendicular line. The perpendicular distance L between the control points of the convex peak and the concave valley and the corresponding sides is equal.

[0056] Furthermore, the value of L ranges from 2mm to 10mm (e.g., it can be 2mm, 3mm, 4mm, 5mm, 6mm, 10mm, etc.). Preferably, L is 5mm.

[0057] For example, such as Figure 3 As shown, the regular polygon is a regular hexagon. The two endpoints of each side of the regular hexagon are called the first endpoint and the second endpoint, described in a clockwise direction, with the first endpoint closer to the starting position: the first endpoint of each side of the regular hexagon corresponds to the endpoint of the Bézier curve 1 closest to the convex peak, and the second endpoint of each side of the regular hexagon corresponds to the endpoint of the Bézier curve 1 closest to the concave valley; or, the first endpoint of each side of the regular hexagon corresponds to the endpoint of the Bézier curve 1 closest to the concave valley, and the second endpoint of each side of the regular hexagon corresponds to the endpoint of the Bézier curve 1 closest to the convex peak. When using a regular hexagon, the six Bézier curves 1 are connected to form a reference curve with six convex peaks and six concave valleys alternately distributed circumferentially, forming a total of 12 control points.

[0058] Furthermore, the cylinder walls of the first outer cell 4 and the first inner cell 5 are both twisted and extended along the height direction, and the cylinder walls of the second outer cell 6 and the second inner cell 7 are both twisted and extended along the height direction.

[0059] Furthermore, the torsion angle of the upper cross-section of the first outer unit cell 4 and the first inner unit cell 5 relative to the lower cross-section is 10° to 60° (e.g., 10°, 20°, 30°, 60°, etc.); the torsion angles of the first outer unit cell 4 and the first inner unit cell 5 are equal in magnitude and in the same direction; the torsion angles of the second outer unit cell 6 and the second inner unit cell 7 are equal in magnitude and in the same direction, the torsion angle of the second outer unit cell 6 is equal in magnitude and opposite in direction to that of the first outer unit cell 4, and the torsion angle of the second inner unit cell 7 is equal in magnitude and opposite in direction to that of the first inner unit cell 5. Preferably, the torsion angle is 30°. By arranging the upper and lower sections in opposite torsional directions, the energy-absorbing structure can counteract the overall deflection trend caused by unidirectional torsion under different working conditions, thereby improving stability.

[0060] Further, the radius of the inscribed circle 3 of the first outer unit cell 4 is 20mm to 100mm (e.g., 20mm, 30mm, 50mm, 60mm, 100mm, etc.), and the radius of the inscribed circle 3 of the first inner unit cell 5 is 0.4 to 0.8 times the radius of the inscribed circle 3 of the first outer unit cell 4 (e.g., 0.4 times, 0.5 times, 0.6 times, 0.8 times, etc.). Preferably, the radius r of the inscribed circle 3 of the first outer unit cell 4 is 50mm, and the radius of the inscribed circle 3 of the first inner unit cell 5 is 0.6 times the radius of the inscribed circle of the first outer unit cell 4. The dimensions of the second outer unit cell 6 and the second inner unit cell 7 are similar.

[0061] Furthermore, the first outer unit cell 4, the first inner unit cell 5, the second outer unit cell 6, and the second inner unit cell 7 all have the same layer height, ranging from 10mm to 60mm (e.g., 10mm, 20mm, 30mm, 60mm, etc.), and the same wall thickness t, ranging from 0.3mm to 3mm (e.g., 0.3mm, 1mm, 2mm, 3mm, etc.). Preferably, the layer height is 20mm and the wall thickness is 1mm.

[0062] For example, refer to Figure 4Six second energy-absorbing cells are used, arranged in a circular array uniformly based on the first energy-absorbing cells located between the upper panel 8 and the lower panel 9 (adjacent second energy-absorbing cells are arranged at 60° intervals, i.e., θ is 60°). The central axis of the first energy-absorbing cell is coaxial with the central axes of the upper panel 8 and the lower panel 9. The distance between the center of any second energy-absorbing cell and the center of the first energy-absorbing cell is 1.1 to 1.8 times the radius of the inscribed circle 3 of the first outer cell 4 (e.g., 1.1, 1.3, 1.4, 1.5, 1.8, etc.). For example, the distance between the center of each second energy-absorbing cell and the center of the first energy-absorbing cell is equal, and is 1.3 times the radius of the inscribed circle 3 of the first outer cell 4. That is, when the radius r of the inscribed circle 3 of the first outer cell 4 is 50 mm, the distance between the center of each second energy-absorbing cell and the center of the first energy-absorbing cell is 65 mm.

[0063] Furthermore, the upper panel 8, lower panel 9, first outer unit cell 4, first inner unit cell 5, second outer unit cell 6, and second inner unit cell 7 are all made of metallic materials and integrally formed using metal additive manufacturing. Preferably, the metallic material is 316L stainless steel. In an optional embodiment, the metal additive manufacturing method is selective laser melting, laser powder bed melting, direct metal laser sintering, or electron beam melting. After forming, the energy-absorbing structure can undergo stress-relieving heat treatment, support removal, and surface cleaning to improve structural dimensional stability and service reliability.

[0064] Furthermore, the thickness of both the upper panel 8 and the lower panel 9 is 0.5mm to 5mm (e.g., 0.5mm, 1mm, 2mm, 5mm, etc.). Preferably, the thickness of both the upper panel 8 and the lower panel 9 is 1mm, and the thickness of the energy-absorbing core layer is 40mm, thus the total height of the energy-absorbing structure based on the nested corrugated compression-torsion metamaterial is 42mm.

[0065] The parameters in the above numerical ranges can be combined arbitrarily to form feasible solutions.

[0066] The working principle of this invention is as follows:

[0067] When the energy-absorbing structure is subjected to a compressive load along its height, the load is first transferred from the upper panel 8 to the second outer unit cell 6 and the second inner unit cell 7. Since both the second outer unit cell 6 and the second inner unit cell 7 are corrugated torsional thin-walled structures, their walls undergo local bending, torsional folding, and thin-wall buckling after compression. As the compressive displacement increases, the load continues to be transferred to the first outer unit cell 4 and the first inner unit cell 5 via the mirror interface. The first outer unit cell 4 and the first inner unit cell 5 undergo opposite torsional folding and crushing deformation, thus forming a graded crushing energy absorption process. Because the torsional directions of the first outer unit cell 4 and the second outer unit cell 6 are opposite, and the torsional directions of the first inner unit cell 5 and the second inner unit cell 7 are opposite, the torsional deformation trends of the upper and lower cell layers during compression can mutually restrain each other, thereby reducing overall rotational instability. Since there are no radial direct connections between the inner and outer cell elements, asynchronous buckling and graded crushing can occur between the inner and outer cell elements, extending the effective energy absorption stroke of the structure.

[0068] When the energy-absorbing structure is subjected to an explosive impact load, the upper panel 8 first bears the explosive impact and undergoes localized indentation deformation, and then the impact load is transferred to the energy-absorbing core layer. The energy-absorbing core layer absorbs the explosive impact energy through the buckling of the corrugated walls of the first outer unit cell 4, the first inner unit cell 5, the second outer unit cell 6, and the second inner unit cell 7, reverse torsional folding, asynchronous crushing of inner and outer cells, and the coordinated deformation of the array of multiple energy-absorbing cell groups, thereby reducing the maximum displacement, peak velocity, and stress concentration of the lower panel 9.

[0069] Example 2: To verify the compressive energy absorption performance of the energy-absorbing structure of the present invention, an axial compression simulation of the energy-absorbing structure of the present invention was performed using the finite element method. The simulation model adopted the preferred structural parameters in Example 1 (L is 5mm, the torsion angle is 30°; the radius of the inscribed circle 3 of the first outer unit cell 4 is 50mm, and the radius of the inscribed circle 3 of the first inner unit cell 5 is 0.6 times the radius of the inscribed circle of the first outer unit cell 4 (the dimensions of the second outer unit cell 6 and the second inner unit cell 7 are similar); the single-layer height of the first outer unit cell 4, the first inner unit cell 5, the second outer unit cell 6, and the second inner unit cell 7 is 20mm, and the wall thickness is 1mm; the thickness of the upper panel 8 and the lower panel 9 is 1mm, and the total height of the energy-absorbing structure in this example is 42mm; the material is 316L stainless steel, and the regular polygon is a regular hexagon). The compression direction is the height direction of the sandwich structure. The lower panel 9 is fixed, and a pressure plate is set above the upper panel 8. The pressure plate moves downward along the height direction at a speed of 0.5mm / s, and the loading displacement is 24mm.

[0070] During compression simulation, the force-displacement curves and specific energy absorption-displacement curves of the energy-absorbing structure of this invention and the first comparative structure are extracted. The first comparative structure is a straight-sided hexagonal cross-section replaced with the continuous corrugated closed cross-section of this invention, while maintaining the same structural parameters. Exploded views of the energy-absorbing structure of this invention and the first comparative structure in this embodiment are shown below. Figure 2 , Figure 5 As shown.

[0071] like Figure 8 (a) and Figure 8 As shown in (b), under the same axial compression conditions, the load-bearing capacity of the energy-absorbing structure of the present invention is significantly higher than that of the first comparative structure in the initial stage of compression, and maintains a relatively gentle load change during the middle and later stages of compression. Simultaneously, the specific energy absorption curve of the energy-absorbing structure of the present invention is higher than that of the first comparative structure throughout the entire compression displacement range, and continues to rise with increasing displacement. This demonstrates that by using the continuous corrugated closed section formed by Bézier curve 1, the cell wall can participate more fully in bending, folding, and crushing deformation, enabling the structure to form a continuous energy dissipation process during axial compression, thereby improving the compression bearing capacity and specific energy absorption level.

[0072] Example 3: To verify the explosion resistance of the structure of the present invention, the CONWEP method was used to apply a TNT equivalent explosion load to the energy-absorbing structure of the present invention in Example 2. The explosive type was TNT equivalent, the explosive equivalent was 100g, the explosion distance was 100mm, the explosion point was located directly above the center of the upper panel 8, the simulation time was 1.5ms, and material failure and fracture were not considered during the simulation.

[0073] During the explosion simulation, the upper panel displacement response, lower panel displacement response, and total energy absorption curve of the energy-absorbing structure of the present invention and the first comparative structure corresponding to Example 2 were extracted. The explosion load conditions used in the simulation of the first comparative structure were consistent with those of the present invention.

[0074] like Figure 9 (a) Figure 9 As shown in (b), under the same explosive impact conditions, the peak displacement of the upper and lower panels of the energy-absorbing structure of the present invention in the initial stage of impact is lower than that of the first comparative structure, wherein... Figure 9 As can be seen in (b), the peak displacement of the lower panel decreases more significantly. Because explosive loads are characterized by short duration and high instantaneous peak values, the maximum displacement at the initial stage of impact better reflects the degree of deformation of the panel at the most unfavorable loading moment; subsequent fluctuations in the displacement curve mainly correspond to the vibration and rebound process of the structure after impact. Therefore, combining the initial peak displacement and... Figure 10 As can be seen from the total energy absorption curve, the energy absorption structure of the present invention can maintain a higher energy absorption level while reducing the maximum impact deformation of the panel, indicating that it has good impact energy dissipation capability and back-burst surface deformation suppression capability.

[0075] Example 4: To further verify the influence of the energy-absorbing structure of the present invention on its resistance to pressure and explosion, based on the simulation conditions of Examples 2 and 3, the following were set: Figure 6The single-layer energy-absorbing structure shown is a second comparative structure. The energy-absorbing core layer of the single-layer energy-absorbing structure retains the first outer unit cell 4 and the first inner unit cell 5, and removes the second outer unit cell 6 and the second inner unit cell 7 arranged in a mirror image along the height direction to form a single-layer energy-absorbing structure. The associated structural parameters and loading conditions are consistent with the structure of the present invention.

[0076] like Figures 11 to 13 As shown, under the same axial compression and explosive impact conditions, the energy-absorbing structure of this invention exhibits different response characteristics compared to the second comparative structure. Figure 11 (a) It can be seen that the second comparative structure exhibits a load peak in the initial stage of compression, but the load subsequently decreases continuously with increasing displacement; the initial peak value of the energy-absorbing structure of the present invention is higher than that of the second comparative structure, and it still maintains a certain load-bearing capacity and shows an increase in load in the subsequent compression stage, indicating that the double-layer structure can enable the upper and lower cells to participate in the crushing deformation successively, giving the compression process a staged energy consumption characteristic. Figure 11 As shown in (b), under the same axial compression condition, the specific energy absorption curve of the energy-absorbing structure of the present invention continuously increases with the increase of displacement, and is generally higher than that of the second comparative structure. This indicates that the upper and lower double-layer mirror-image reverse torsional arrangement can extend the effective crushing stroke, allowing more cells to participate in energy absorption, thereby improving the specific energy absorption level of the structure. Figure 12 (a) and Figure 12 (b) It is evident that the peak displacements of both the upper and lower panels of the energy-absorbing structure of this invention during the initial impact phase are lower than those of the second comparative structure, with the lower panel showing a more significant reduction in peak displacement. Due to the short duration and high instantaneous peak value of the explosive load, the maximum displacement during the initial impact phase better reflects the degree of deformation of the panel at the most unfavorable loading moment; subsequent fluctuations in the displacement curve mainly correspond to the vibration and rebound process of the structure after the impact. Therefore, combined with... Figure 11 Compression response in Figure 12 The initial displacement peak and Figure 13 As can be seen from the total energy absorption curve, the energy absorption structure of the present invention can maintain a higher energy absorption level while reducing the maximum impact deformation of the panel, indicating that it has good impact energy dissipation capability and back-burst surface deformation suppression capability.

[0077] Example 5: To further verify the influence of the inner and outer coaxial nested structure on the compression and explosion resistance performance, based on the simulation conditions of Examples 2 and 3, the following were set: Figure 7 The structure shown without embedded inner cell units serves as the third comparative structure. This third comparative structure retains the first and second outer cells, but removes the first and second inner cells. The associated structural parameters, boundary conditions, and loading conditions remain consistent with the structure of this invention.

[0078] like Figures 14 to 16As shown, under the same axial compression and explosive impact conditions, the energy-absorbing structure of this invention exhibits different response characteristics compared to the third comparative structure. Figure 14 (a) As can be seen, the force-displacement curve of the energy-absorbing structure of the present invention is higher than that of the third comparative structure throughout the entire compression process, indicating that the participation of the inner unit cell in bearing the load can improve the compressive bearing capacity of the structure and increase the energy consumption level during the compression process. Figure 14 As shown in (b), under the same axial compression conditions, the specific energy absorption curve of the energy-absorbing structure of the present invention continuously increases with the increase of displacement, and is generally higher than that of the third comparative structure. Figure 15 (a) and Figure 15 (b) It is evident that the peak displacements of the upper and lower panels of the energy-absorbing structure of this invention during the initial impact phase are significantly lower than those of the third comparative structure, with the upper panel showing a more significant reduction in peak displacement. Due to the short duration and high instantaneous peak value of the explosive load, the maximum displacement during the initial impact phase better reflects the degree of deformation of the panel at the most unfavorable loading moment; subsequent fluctuations in the displacement curve mainly correspond to the vibration and rebound process of the structure after the impact. Therefore, combined with... Figure 14 Compression response in Figure 15 The initial displacement peak and Figure 16 The total energy absorption curve shows that the energy-absorbing structure of the present invention can maintain a higher energy absorption level while improving the compressive bearing capacity and reducing the maximum impact deformation of the panel. This indicates that the inner and outer coaxial nested structure is conducive to forming a coordinated bearing and crushing energy absorption process, thereby improving the impact energy dissipation capacity and the deformation suppression capacity of the back burst surface of the structure.

[0079] In summary, this invention utilizes a nested corrugated compressive-torsional metamaterial to form a double-layered, mirror-image, reverse-torsional, coaxially nested, and integrally connected energy-absorbing structure. This structure, comprised of a first outer unit cell 4, a first inner unit cell 5, a second outer unit cell 6, and a second inner unit cell 7, achieves stable, graded crushing energy absorption under compressive loads. Under explosive impact loads, it reduces the displacement response and stress concentration of the lower panel 9 through the coordinated deformation of the multi-cell array. This structure is suitable for applications such as explosion-proof wall panels, explosion-proof enclosures, protective partitions, hazardous materials storage and transportation protection structures, equipment bottom protection, and impact protection for critical equipment.

[0080] 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. An energy-absorbing structure based on nested corrugated compression-torsion metamaterials, characterized in that, It includes an upper panel (8), a lower panel (9), and an energy-absorbing core layer disposed between the upper panel (8) and the lower panel (9) arranged coaxially at intervals; The energy-absorbing core layer includes a first energy-absorbing cell and a plurality of second energy-absorbing cells arranged in a circular array based on the first energy-absorbing cell. The first energy-absorbing cell and the second energy-absorbing cell have the same structure, each including a first outer unit cell (4), a first inner unit cell (5), a second outer unit cell (6), and a second inner unit cell (7). The first inner cell (5) is coaxially disposed inside the first outer cell (4) and a first gap space is formed between the first inner cell (5) and the first outer cell (4). The second inner cell (7) is coaxially disposed inside the second outer cell (6) and a second gap space is formed between the second inner cell (7) and the second outer cell (6) and is arranged in communication with the first gap space. One end of the first outer unit cell (4) and one end of the first inner unit cell (5) are integrally formed and connected to the side of the lower panel (9) near the upper panel (8). One end of the second outer unit cell (6) and one end of the second inner unit cell (7) are integrally formed and connected to the side of the upper panel (8) near the lower panel (9). The first outer unit cell (4) and the second outer unit cell (6) are arranged in a mirror image along the height direction, and the other end of the first outer unit cell (4) and the other end of the second outer unit cell (6) are integrally formed and connected at the mirror interface. The first inner unit cell (5) and the second inner unit cell (7) are arranged in a mirror image along the height direction, and the other end of the first inner unit cell (5) and the other end of the second inner unit cell (7) are integrally formed and connected at the mirror interface.

2. The energy-absorbing structure based on nested corrugated compression-torsion metamaterials according to claim 1, characterized in that, The first outer unit cell (4), the first inner unit cell (5), the second outer unit cell (6), and the second inner unit cell (7) are all corrugated twisted thin-walled structures arranged along the height direction, and their cross sections are all continuous corrugated closed sections. The continuous corrugated closed section is formed by the inner boundary curve and the outer boundary curve. The inner boundary curve is formed equidistantly from the reference curve inwards, and the outer boundary curve is formed equidistantly from the reference curve outwards. The distances between the inner boundary curve, the outer boundary curve and the reference curve are equal. The reference curve is formed by connecting multiple Bézier curves (1) end to end in sequence. Each Bézier curve (1) has an outward convex peak and an inward concave valley. The multiple Bézier curves (1) use a regular polygon (2) and the inscribed circle (3) of the regular polygon (2) as the configuration reference. The two endpoints of each side of the regular polygon (2) are taken as the first endpoint and the second endpoint. The first endpoint of each side of the regular polygon (2) is the endpoint of the corresponding Bézier curve (1) near the outward convex peak, and the second endpoint of each side of the regular polygon (2) is the endpoint of the corresponding Bézier curve (1) near the inward concave valley.

3. The energy-absorbing structure based on nested corrugated compression-torsion metamaterials according to claim 2, characterized in that, The Bézier curve (1) is a cubic Bézier curve. The control points of the convex peak and the concave valley are determined as follows: the sides of the regular polygon (2) are divided into three equal parts from the first endpoint to the second endpoint to form two perpendicular lines that are perpendicular to the corresponding sides: the first perpendicular line and the second perpendicular line. The first perpendicular line is close to the first endpoint. The control point of the convex peak is located on the first perpendicular line, and the control point of the concave valley is located on the second perpendicular line. The vertical distance L between the control points of the convex peak and the concave valley and the corresponding sides is equal.

4. The energy-absorbing structure based on nested corrugated compression-torsion metamaterials according to claim 3, characterized in that, The value of L ranges from 2mm to 10mm.

5. The energy-absorbing structure based on nested corrugated compression-torsion metamaterials according to claim 2, characterized in that, The radius of the inscribed circle (3) of the first outer unit cell (4) is 20 mm to 100 mm, and the radius of the inscribed circle (3) of the first inner unit cell (5) is 0.4 to 0.8 times the radius of the inscribed circle (3) of the first outer unit cell (4).

6. The energy-absorbing structure based on nested corrugated compression-torsion metamaterials according to claim 2, characterized in that, The distance between the center of each second energy-absorbing cell and the center of the first energy-absorbing cell is equal, and the distance between the center of the second energy-absorbing cell and the center of the first energy-absorbing cell is 1.1 to 1.8 times the radius of the inscribed circle (3) of the first outer cell (4).

7. The energy-absorbing structure based on nested corrugated torsion metamaterials according to claim 1, characterized in that, The first outer unit cell (4), the first inner unit cell (5), the second outer unit cell (6), and the second inner unit cell (7) have the same single-layer height, which is 10mm to 60mm, and the same wall thickness, which is 0.3mm to 3mm.

8. The energy-absorbing structure based on nested corrugated compression-torsion metamaterial according to claim 1, characterized in that, The cylinder walls of the first outer cell (4) and the first inner cell (5) are twisted and extended along the height direction, and the cylinder walls of the second outer cell (6) and the second inner cell (7) are twisted and extended along the height direction.

9. The energy-absorbing structure based on nested corrugated compression-torsion metamaterials according to claim 8, characterized in that, The torsion angle of the upper section of the first outer unit cell (4) and the first inner unit cell (5) relative to the lower section is 10° to 60°; the torsion angles of the first outer unit cell (4) and the first inner unit cell (5) are equal in magnitude and in the same direction; the torsion angles of the second outer unit cell (6) and the second inner unit cell (7) are equal in magnitude and in the same direction, the torsion angles of the second outer unit cell (6) and the first outer unit cell (4) are equal in magnitude and opposite in direction, and the torsion angles of the second inner unit cell (7) and the first inner unit cell (5) are equal in magnitude and opposite in direction.

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