Bionic sagittaria sagittifolia flower metamaterial capable of regulating and controlling positive and negative Poisson ratios

Abstract

The invention discloses a bionic arrowhead flower metamaterial capable of regulating and controlling the positive and negative Poisson ratio. A unit cell structure of the metamaterial is formed by combining a central circular ring and three peripheral curve blades which take arrowhead flower petals as inspiration and rotate around a circle center O in a circumferential mode. The geometric parameters of the unit cell are respectively the outer diameter d0 of the central circular ring, the wall thickness t0, the radius R1 of the curved blade and the thickness t1 of the blade. The bionic metamaterial unit cells form an n * n complete structure through transverse and longitudinal array combination. According to the bionic metamaterial disclosed by the invention, the controllable positive and negative Poisson's ratio characteristic and excellent bearing capacity and impact resistance are realized. The invention provides a brand new technical path for cross-field engineering application of bionic metamaterials.

Description

Technical Field

[0001] This invention relates to the field of metamaterial structure design and engineering applications, and can achieve dynamic control of the positive and negative Poisson's ratio of metamaterials / structures by adjusting the structural geometric parameters. Background Technology

[0002] The concept of "metamaterials" was introduced in 21st-century physics. These materials, through artificially designed composite structures, achieve extraordinary physical properties unattainable by natural materials, with wide applications in acoustics, optics, thermodynamics, mechanics, and electromagnetism. In mechanics, zero- and negative Poisson's ratio materials / structures, as typical mechanical metamaterials, exhibit unique properties. Unlike positive Poisson's ratio materials, which contract laterally (or expand) under tension (or compression), zero Poisson's ratio materials maintain lateral invariance under longitudinal tension (or compression), while negative Poisson's ratio materials exhibit the unique mechanical property of lateral expansion (or contraction) under longitudinal tension (or compression). The special mechanical responses of zero- and negative Poisson's ratio materials / structures provide new pathways for metamaterial structural design, offering structural and technological innovations for fields such as deployable antennas (aerospace) and soft robotics (human-computer interaction).

[0003] Most materials in nature have a fixed Poisson's ratio and cannot be dynamically adjusted. This uniformity makes it difficult for materials to adapt to complex application scenarios. For example, in the aerospace field, wings need to maintain a zero Poisson's ratio during cruise (for stable aerodynamic shape) while simultaneously improving their shock resistance through negative Poisson's ratio during takeoff and landing. Current technologies struggle to achieve both simultaneously. These characteristics make materials / structures with adjustable positive and negative Poisson's ratios have considerable potential and application value in engineering.

[0004] Zero- and negative Poisson's ratio adjustable materials / structures have shown tremendous potential for breakthrough applications in the biomedical field. Their unique axial and radial deformation response mechanisms are highly compatible with the dynamic physiological environment of the human body. In the application of artificial vascular stents, the zero- and negative Poisson's ratio characteristics can precisely control the radial support force, avoiding the risk of vascular collapse caused by improper Poisson's ratio in traditional stents, and continuously maintaining the vasculature open. In the epidermal contact design of wearable devices, zero- and negative Poisson's ratio structures can simulate the deformation compatibility of human tissue, reduce mechanical friction damage between the device and the skin, and adapt to the needs of long-term wear.

[0005] Existing designs with adjustable positive and negative Poisson's ratios still have limitations. For example, achieving positive and negative Poisson's ratio conversion through multi-material combinations mainly relies on the stiffness differences between different materials, has stringent material compatibility requirements, and stress concentration can easily occur at multi-material connections, leading to failure under large deformations. Therefore, research on metamaterial structures that go beyond traditional adjustable Poisson's ratio materials and achieve adjustable negative Poisson's ratios by adjusting the geometric parameters of the same material / structure is imperative. Summary of the Invention

[0006] To address the aforementioned problems, this invention aims to provide a biomimetic metamaterial with an adjustable Poisson's ratio, inspired by the arrowhead flower. The metamaterial's unit cell consists of a central ring and three outer curved blades inspired by arrowhead flower petals. The upper curved blades are arranged in a circular array around the center O of the central ring, with the vertical y-axis as the axis of symmetry, forming the three curved blades. The angle between the centerlines of each blade is 120°. Based on this, the novel unit cell is arrayed in both horizontal and vertical directions to form an n×n metamaterial structure. The biomimetic metamaterial of this invention exhibits an adjustable Poisson's ratio from positive to negative and good energy absorption capacity. Changes in the geometric parameters of the unit cell structure have a significant impact on the overall mechanical properties of the structure.

[0007] To achieve the objectives of this invention, the invention is implemented through the following technical solutions:

[0008] A further improvement is that the biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratio can be made of one of the following materials: metal, shape memory alloy, composite material, or thermoplastic polyurethane superelastic material, and can be prepared by 3D printing technology.

[0009] Further improvements are made in the following: The outer diameter of the central ring of the biomimetic arrowhead flower metamaterial unit cell with adjustable positive and negative Poisson's ratios is d0, and the wall thickness is t0. The arc segments of the three curved blades connected to the outer periphery of the central ring are formed by the intersection of two equally sized circles O and O1 on the same horizontal straight line with the central ring. The radius of curvature of the three curved blades is R1, the wall thickness is t1, and the arc length S1 = πR1 / 3 - (π / 180) × arctan(d0 / 2R1). The edges of the curved blades are connected by straight lines, the edge thickness of the blades is also t1, and the edge length of the blades is L1 = 0.52R1. The three vertices on the center lines of the three curved blades are all located at the edge of a circle with center O and radius R1.

[0010] Further improvements lie in the use of biomimetic arrowhead flower metamaterial unit cells with adjustable positive and negative Poisson's ratios, which are combined in a linear array in both horizontal and vertical directions to form an n×n complete structure. When arrayed horizontally, the vertical segments L at the upper edges of the two curved leaves on the lower left and lower right are... p The blades are of equal size and lie on the same straight line. When arrayed vertically, the 120° circumferential array of the three blades ensures that the endpoints of the left and right edges of the upper curved blade and the endpoints of the lowest edges of the lower left and lower right curved blades lie on the same vertical line, thus automatically achieving vertical arraying.

[0011] Further improvements are made in the ABAQUS finite element software preprocessing module, where material properties, analysis steps, contact properties, boundary conditions, and load conditions are first set for the structure, and the structure is meshed into a finite element mesh, thereby performing quasi-static compression simulation calculations on the structure.

[0012] Further improvements are made by using the finite element method ABAQUS simulation software to perform quasi-static compression simulation on the biomimetic arrowhead metamaterial with adjustable positive and negative Poisson's ratios, and obtaining the stress-strain curves, Poisson's ratio-strain curves, and specific energy absorption-strain curves of the biomimetic arrowhead metamaterial structure with adjustable positive and negative Poisson's ratios under quasi-static compressive loads.

[0013] Further improvements are made in the following: the mechanical properties of the biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratio under quasi-static compressive load and its adjustable positive and negative Poisson's ratio effect can be determined by changing parameters such as the diameter d0 and wall thickness t0 of the central ring structure, the radius of curvature R1 and blade thickness t1 of the outer curved blades.

[0014] The beneficial effects of this invention are as follows: Inspired by the biomimetic arrowhead flower, the metamaterial of this invention, with adjustable positive and negative Poisson's ratios, possesses advantages such as lightweight, high specific strength, and adjustable positive and negative Poisson's ratio effects. Changes in the geometric parameters of this metamaterial have a significant impact on the overall mechanical properties of the structure. This biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratios can provide high-performance, highly adaptable metamaterial solutions for aerospace, biomedicine, and mechatronics fields. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the metamaterial unit cell geometry of the biomimetic arrowhead flower with adjustable positive and negative Poisson's ratio, as described in Embodiment 1 of the present invention.

[0016] Figure 2 This is the 4×4 metamaterial structure of the biomimetic arrowhead flower with adjustable positive and negative Poisson's ratio, as described in Embodiment 1 of the present invention.

[0017] Figure 3 The stress-strain curve of the biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratio in Embodiment 2 of the present invention is shown as the change of the radius of curvature R1 of the outer petal-shaped curved leaf under quasi-static compressive load.

[0018] Figure 4 The Poisson's ratio-strain curve of the biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratio in Embodiment 2 of the present invention, under quasi-static compressive load, shows the change in the radius of curvature R1 of the outer petal-shaped curved leaves.

[0019] Figure 5 The specific energy absorption-strain curve of the biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratio in Embodiment 2 of the present invention, under quasi-static compressive load, shows the change in the radius of curvature R1 of the outer petal-shaped curved leaf. Detailed Implementation

[0020] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0021] Example 1

[0022] according to Figure 1 As shown in the diagram, this embodiment provides a schematic diagram of a metamaterial with adjustable positive and negative Poisson's ratios, inspired by the flower shape of the arrowhead. The unit cell structure designed in this invention consists of a central ring and three outer curved blades inspired by arrowhead flower petals. The upper curved blades are arranged in a circular array around the center O of the central ring, with the vertical y-axis as the axis of symmetry. The angle between the centerlines of each blade is 120°. The outer diameter of the central ring is d0, and the wall thickness is t0. The arc segments connecting the three curved blades at the periphery of the central ring are formed by the intersection of two equally sized circles O and O1 on the same horizontal straight line with the central ring. The radius of curvature of the three curved blades is R1, and the wall thickness is t1. The edges of the curved blades are connected by straight lines, and the edge thickness of the blades is also t1. The three vertices on the centerlines of the three curved blades are all located at the edge of a circle with center O and radius R1.

[0023] according to Figure 2 As shown, this embodiment provides a 4×4 structure of a biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratios. The biomimetic arrowhead flower metamaterial unit cell with adjustable positive and negative Poisson's ratios is constructed into an n×n complete structure through linear arrays in the horizontal and vertical directions. When arrayed horizontally, the vertical line segments L at the upper edges of the two curved blades at the lower left and lower right are... p The blades are of equal size and lie on the same straight line. When arrayed vertically, the 120° circumferential array of the three blades ensures that the endpoints of the left and right edges of the upper curved blade and the endpoints of the lowest edges of the lower left and lower right curved blades lie on the same vertical line, thus automatically achieving vertical arraying.

[0024] The biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratio can be made of one of the following materials: metal, shape memory alloy, composite material, or thermoplastic polyurethane superelastic material, and can be prepared by 3D printing technology.

[0025] Example 2

[0026] In the preprocessing module of the ABAQUS finite element software, material properties, analysis steps, contact properties, boundary conditions, and load conditions are set for the structure, and the finite element mesh of the structure is generated, thereby performing quasi-static compression simulation calculations on the structure.

[0027] Material properties were set in ABAQUS finite element simulation software. Aluminum alloy was selected as the research object, with elastic modulus E = 69 GPa, Poisson's ratio μ = 0.3, and yield stress σ = 76 MPa.

[0028] according to Figure 3 As shown, this embodiment provides stress-strain curves of a biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratios under quasi-static compressive loading, varying with the radius of curvature R1 of the outer petals. It can be seen that the biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratios exhibits the best mechanical properties with a radius of curvature R1 = 90 mm. Within the linear elastic range, the elastic modulus of the biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratios decreases with increasing radius of curvature R1. In the stress plateau region, the stress of all three materials remains essentially constant with increasing strain, exhibiting a relatively long stress plateau period, which can effectively increase the energy absorption of the structure. Finally, the stress of all three materials rises rapidly, reaching the dense region.

[0029] according to Figure 4 As shown in the figure, this embodiment provides the Poisson's ratio-strain curves of a biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratios under quasi-static compressive loading, varying with the radius of curvature R1 of the outer petals and leaves. It can be seen that the material with R1 = 90 mm has a positive Poisson's ratio, while the materials with R1 = 100 mm and 110 mm have negative Poisson's ratios, exhibiting a significant negative Poisson's ratio effect. Furthermore, the negative Poisson's ratio effect of the biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratios increases with increasing radius R1.

[0030] according to Figure 5 As shown in the figure, this embodiment provides the specific energy absorption-strain curves of a biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratios under quasi-static compressive load, as a function of the radius of curvature R1 of the outer petals and leaves. It can be seen that the specific energy absorption value of the material with R1 = 90 mm is greater than that of the materials with R1 = 100 mm and 110 mm, and all three groups of materials exhibit good energy absorption effects.

[0031] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A metamaterial with adjustable positive and negative Poisson's ratio, inspired by the flower of the arrowhead, characterized in that: The structure is composed of multiple periodic unit cells arrayed along the horizontal and vertical directions. The designed unit cell structure consists of a central ring and three outer curved blades inspired by arrowhead flower petals. The upper curved blades are arranged in a circular array around the center O of the central ring with the vertical y-axis as the axis of symmetry, forming three curved blades, with the center lines of each blade forming an angle of 120°.

2. The biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratio according to claim 1, characterized in that: The outer diameter of the central ring is d0, and the wall thickness is t0. The arc segments of the three curved blades connected to the outer perimeter of the central ring are formed by the intersection of two equal-sized circles O and O1 on the same horizontal straight line with the central ring. The radius of curvature of the three curved blades is R1, the wall thickness is t1, and the arc length S1 = πR1 / 3 - (π / 180) × arctan(d0 / 2R1). The edges of the curved blades are connected by straight lines, and the edge thickness of the blades is also t1, with an edge length L1 = 0.52R1. The three vertices on the center lines of the three curved blades are all located on the edge of a circle with center O and radius R1.

3. The biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratio according to claim 1, characterized in that: A biomimetic arrowhead flower metamaterial unit cell with adjustable positive and negative Poisson's ratios is constructed into an n×n complete structure through linear arrays in both horizontal and vertical directions. When arrayed horizontally, the vertical segments L at the upper edges of the two curved leaves on the lower left and lower right are... p The blades are of equal size and aligned on the same straight line. When arrayed vertically, the 120° circular array of the three blades ensures that the endpoints of the left and right edges of the upper curved blade are aligned with the endpoints of the lowest edges of the lower left and right curved blades, thus automatically achieving vertical arraying. The out-of-plane thickness of this biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratio is H. z This is not shown in the floor plan.

4. The biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratio according to claim 1, characterized in that: It was prepared using 3D printing technology.

5. The metamaterial with adjustable positive and negative Poisson's ratio based on the biomimetic arrowhead flower according to claim 1, characterized in that: The biomimetic arrowhead flower metamaterial with adjustable positive and negative Poisson's ratio can be made of one of the following materials: metal, shape memory alloy, composite material, or thermoplastic polyurethane superelastic material.

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