A three-dimensional horse-shoe microstructure based biomimetic mesh metamaterial

Abstract

This invention provides a biomimetic mesh metamaterial based on a three-dimensional horseshoe-shaped microstructure, belonging to the field of metamaterial design technology. This metamaterial is obtained by spatially arranging a three-dimensional unit cell structure. The three-dimensional unit cell structure is formed by connecting the upper and lower vertices of the horseshoe-shaped microstructures along the eight lateral edges of a regular octahedron in the same bending direction to form a cage-like structure. In the three-dimensional unit cell structure, there are no structures distributed along the transverse edges of the regular octahedron. The upper and lower parts, bounded by the transverse edges, are considered as spatial four-ligament chiral units in the longitudinal direction, and are centrally symmetrical about the center point of the regular octahedron. The plane containing each horseshoe-shaped microstructure has an equal angle with the adjacent lateral surface of the regular octahedron. This metamaterial uses the three-dimensional horseshoe shape as the basic functional unit, forming a three-dimensional periodically arranged mesh metamaterial through a regular octahedron lattice. It possesses a large stress-strain control range while also exhibiting the nonlinear mechanical properties of biological tissues and unconventional tensile-torsional coupling mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of metamaterial design technology, and in particular to a biomimetic mesh metamaterial based on a three-dimensional horseshoe-shaped microstructure. Background Technology

[0002] With the ever-increasing demand for new material properties and the continuous development of new fabrication processes, the artificial design and synthesis of metamaterials with special properties has gradually become a research hotspot. Metamaterials generally refer to artificial functional materials that use conventional natural materials as a substrate, employing artificially designed microstructures as basic units, and arranging them periodically to achieve special properties rarely found or not possessed by natural materials. The unusual and special properties of metamaterials are determined by the geometric configuration of their microstructures, influenced by design parameters and component materials, but unrelated to the properties of the component materials themselves. Metamaterials exhibit promising characteristics in many aspects, including adjusting porosity, controlling mechanical properties, achieving unconventional mechanical properties, and acoustic and phonon properties.

[0003] As one of the emerging research directions in metamaterials in recent years, mechanics-materials science and structural genome engineering have proposed a new research approach for metamaterial design: exploring the interrelationship between the comprehensive performance of the structure and factors such as material composition, component configuration, and manufacturing process. Through multi-scale structural and component design, precise control of performance, function, intelligence, and biomimicry can be achieved. Studying the intrinsic relationship between component configuration and material properties and functions provides important insights for metamaterial design. Currently, chiral and helical structures with deformation mode conversion characteristics are widely used in mechanical metamaterial design. They can achieve negative Poisson's ratio in two dimensions and J-type stress-strain mechanical response similar to soft biological tissues in three dimensions. In recent years, chiral and helical structures have achieved compression-torsional coupling characteristics at two-dimensional and three-dimensional levels. However, most existing designs are still limited to realizing single unconventional mechanical properties, lacking the intrinsic relationship between component structure and material properties, as well as the comprehensive practice and application of multiple unconventional mechanical properties, making it difficult to achieve multifunctional integration in a single metamaterial.

[0004] Chiral structures are currently widely used in the design of two-dimensional metamaterials. They are mainly divided into two types: one is a combination of a centrally symmetric closed curve and a centrally symmetric linear structure that does not pass through the center of symmetry; the other is a centrally symmetric nonlinear structure.

[0005] In the design of negative Poisson's ratio metamaterials, existing literature reports can be summarized into three recognized basic structures: reentry structures, chiral structures, and rotationally rigid structures.

[0006] For biomimetic material design, the existing approach is mainly inspired by the internal mechanisms of living organisms, analyzing the formation mechanism of their various mechanical properties, and designing and preparing materials in imitation of their structures. The main approach is to achieve the transformation of deformation modes through nonlinear structures, such as horseshoe microstructures and helical microstructures.

[0007] In the design of compression-torsion coupled metamaterials, the existing design approach mainly involves setting up a chiral structure. When the overall structure is subjected to compressive load, the compressive deformation along the load direction can be transformed into torsional deformation perpendicular to the load direction.

[0008] Current research on chiral structure applications and negative Poisson's ratio metamaterial design is still concentrated at the two-dimensional level, making it difficult to directly extend from two-dimensional to three-dimensional levels. Recently reported three-dimensional structures with chiral characteristics are all splicing and extension of two-dimensional structures in three-dimensional directions, resulting in redundant material usage and difficulty in achieving large-scale deformation.

[0009] In the design of biomimetic materials, spiral microstructures are applied to the design of three-dimensional biomimetic materials by means of weaving and arrangement. However, the problem is that weaving is difficult to achieve large-scale deformation due to the mutual restriction between fibers, and the arrangement is complicated to control due to the large number of control parameters of spiral microstructures.

[0010] In the design of compression-torsion coupled metamaterials, current solutions are limited by the chiral characteristics of the structure, and isotropic structures can only achieve a small range of torsional angle control. If the torsional angle is increased, the torsional coupling in both directions must be sacrificed, and a larger range of torsion can only be achieved in the loaded direction, and it is difficult to control the torsional deformation rate. Summary of the Invention

[0011] This invention addresses the limitation of current three-dimensional mechanical metamaterials in terms of their single function. It proposes a biomimetic mesh metamaterial based on a three-dimensional horseshoe-shaped microstructure that simultaneously possesses the nonlinear mechanical properties of soft biological tissue, negative Poisson's ratio, and tensile-torsional coupling within a large deformation range. Furthermore, the macroscopic configuration mechanical properties can be controlled through microstructural parameters, thus enabling customized targeting of unconventional mechanical properties. This metamaterial uses a three-dimensional horseshoe shape as its basic functional building block, forming a three-dimensional periodically arranged mesh metamaterial through a lattice of regular octahedrons. While exhibiting a large stress-strain control range (200% strain range), it also possesses the nonlinear mechanical properties of biological tissue and the unconventional tensile-torsional coupling mechanical properties. The macroscopic structural physical and mechanical properties of this metamaterial are dominated by the microstructural functional building blocks, with minimal influence from the properties of the component materials. Polymers, photosensitive resins, and rubber can be used as carriers.

[0012] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0013] A biomimetic mesh metamaterial based on a three-dimensional horseshoe-shaped microstructure is obtained by spatial arraying a three-dimensional unit cell structure.

[0014] The three-dimensional single-cell structure is achieved by connecting the upper and lower vertices of the horseshoe-shaped microstructure along the eight side edges of the regular octahedron in the same bending direction to form a cage-like structure.

[0015] In the three-dimensional unit cell structure, there are no structures distributed along the transverse edges of the regular octahedron. The upper and lower parts bounded by the transverse edges are regarded as spatial four-ligament chiral units in the longitudinal direction, and are centrally symmetrical about the center point of the regular octahedron. The plane containing each horseshoe-shaped microstructure has an equal angle with the side surface of the adjacent regular octahedron.

[0016] The metamaterial design method includes the following steps:

[0017] S1. Using a set of lateral edges connecting the top and bottom vertices of a regular octahedron as chords, construct spatial horseshoe-shaped microstructures with the same central angle but opposite directions on two planes passing through the lateral edges and perpendicular to each other. The two horseshoe-shaped microstructures are symmetrical about the connected nodes.

[0018] S2. Construct eight horseshoe-shaped microstructures that are centrally symmetrical about the center point of the octahedron along the eight longitudinal lateral edges of the octahedron:

[0019] Continue to construct three sets of spatial horseshoe-shaped microstructures according to the method in step S1. The four sets of spatial horseshoe-shaped microstructures are symmetrical about the center of the straight line where the top and bottom vertices of the octahedron are located, and the planes where the four sets of chords are located have an equal angle of 90° between them, forming a four-ligament horseshoe-shaped chiral structure.

[0020] S3. Set nodal spheres with a diameter of 1.2 times that of horseshoe-shaped microstructures at all nodal positions to form a three-dimensional unit cell;

[0021] S4. Using the line connecting the three sets of nodes in relative positions of the regular octahedron as the three principal axes, the three-dimensional unit cells are periodically arranged along the three principal axes to form a three-dimensional horseshoe-shaped mesh metamaterial with square lattice.

[0022] In step S1, the horseshoe-shaped microstructure changes its shape by altering the corresponding central angle.

[0023] The horseshoe-shaped microstructure can be transformed into either of the following two structures:

[0024] ① Semi-elliptical microstructure: Construct an ellipse with the side edge as the axis, taking the top and bottom halves in opposite directions;

[0025] ② Straight rod joint microstructure: Keeping the node distance unchanged, the horseshoe-shaped microstructure is scaled down proportionally except for the diameter, and the two ends are connected to the original nodes with straight rods of equal diameter.

[0026] In step S2, the four-ligament horseshoe-shaped chiral structure can be replaced with a three-ligament horseshoe-shaped chiral structure, that is, three sets of spatial horseshoe-shaped microstructures are constructed with an angle of 120° between them. Correspondingly, in step S4, the horizontal periodic arrangement direction is replaced with an angle of 120°, and the square lattice formed becomes a triangular lattice.

[0027] In step S2, the four-ligament horseshoe-shaped chiral structure can be replaced with a six-ligament horseshoe-shaped chiral structure, that is, six sets of spatial horseshoe-shaped microstructures are constructed with an angle of 60° between them. Correspondingly, in step S4, the horizontal periodic arrangement direction is replaced with an angle of 60°, and the square lattice formed becomes a hexagonal lattice.

[0028] The metamaterials are used in the design of flexible electronic devices, soft robots, longitudinal wave-rotational wave converters, and biological flaw detection sensors.

[0029] The above technical solution has at least the following advantages compared with the existing technology:

[0030] The aforementioned scheme designs a three-dimensional metamaterial integrating multiple unconventional mechanical properties and proposes a three-dimensional biomimetic material design method based on a horseshoe-shaped microstructure. This method allows for precise control of the nonlinear mechanical properties of the macroscopic configuration by adjusting the geometric parameters of the microstructure; it can reproduce the nonlinear mechanical properties of three-dimensional biological tissues. This invention proposes a simpler tension-torsion coupled metamaterial design method, enabling the achievement of a wider range of strain and larger torsion angles, significantly greater than existing structures. The range of torsion angles and the rate of change of torsion angle with strain can be controlled through structural parameters. Due to the integration of multiple unconventional mechanical properties, this invention has broad application prospects in flexible electronic devices, soft robots, longitudinal / rotational wave conversion, and biological flaw detection sensors. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the three-dimensional mesh metamaterial, the regular octahedral unit cell, and the horseshoe-shaped microstructure in this invention;

[0033] Figure 2 These are top views of the octahedral unit cell and the square lattice of the four-ligament chiral structure in an embodiment of the present invention, wherein (a) is a top view of the octahedral unit cell and (b) is a top view of the square lattice.

[0034] Figure 3These are top views of the triacylchiral structure unit cell and the triangular lattice in an embodiment of the present invention, wherein (a) is a top view of the triacylchiral structure unit cell and (b) is a top view of the triangular lattice.

[0035] Figure 4 These are top views of the hexagonal ligament chiral structure unit cell and hexagonal lattice in an embodiment of the present invention, wherein (a) is a top view of the hexagonal ligament chiral structure unit cell and (b) is a top view of the hexagonal lattice;

[0036] Figure 5 The stress-strain curves and torsional angle-strain curves are the results of finite element analysis of the four-ligament chiral structure in this embodiment of the invention.

[0037] Figure 6 This is a schematic diagram of a regular octahedral unit cell and a semi-elliptical microstructure in an embodiment of the present invention.

[0038] Figure 7 This is a schematic diagram of the octahedral unit cell and the straight rod joint microstructure in an embodiment of the present invention;

[0039] Figure 8 This is a schematic diagram of the experimental measurement and finite element analysis results curves and corresponding octahedral unit cells used to reproduce the nonlinear mechanical properties of the mouse esophageal wall in this embodiment of the invention. Detailed Implementation

[0040] 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. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0041] This invention provides a biomimetic mesh metamaterial based on a three-dimensional horseshoe-shaped microstructure.

[0042] like Figure 1 This metamaterial is obtained by spatial arraying a three-dimensional unit cell structure;

[0043] The three-dimensional unit cell structure is achieved by connecting the upper and lower vertices of the horseshoe-shaped microstructures along the eight lateral edges of the regular octahedron in the same bending direction to form a cage-like structure. In the three-dimensional unit cell structure, there are no structures distributed along the transverse edges of the regular octahedron. The upper and lower parts bounded by the transverse edges are regarded as spatial four-ligament chiral units in the longitudinal direction, and are centrally symmetrical about the center point of the regular octahedron. The plane where each horseshoe-shaped microstructure is located has the same angle with the adjacent lateral surface of the regular octahedron.

[0044] The metamaterial design method includes the following steps:

[0045] S1. Using a set of lateral edges connecting the top and bottom vertices of a regular octahedron as chords, construct spatial horseshoe-shaped microstructures with the same central angle but opposite directions on two planes passing through the lateral edges and perpendicular to each other. The two horseshoe-shaped microstructures are symmetrical about the connected nodes.

[0046] S2. Construct eight horseshoe-shaped microstructures that are centrally symmetrical about the center point of the octahedron along the eight longitudinal lateral edges of the octahedron:

[0047] Continue to construct three sets of spatial horseshoe-shaped microstructures according to the method in step S1. The four sets of spatial horseshoe-shaped microstructures are symmetrical about the center of the straight line where the top and bottom vertices of the octahedron are located, and the planes where the four sets of chords are located have an equal angle of 90° between them, forming a four-ligament horseshoe-shaped chiral structure.

[0048] S3. Set nodal spheres with a diameter of 1.2 times that of horseshoe-shaped microstructures at all nodal positions to form a three-dimensional unit cell;

[0049] S4. Using the lines connecting the three sets of nodes in relative positions of the regular octahedron as the three principal axes, the three-dimensional unit cells are periodically arranged along these three principal axes to form a three-dimensional horseshoe-shaped mesh metamaterial with a square lattice. For example... Figure 2 As shown.

[0050] In step S1 above, the horseshoe-shaped microstructure changes its shape by changing the corresponding central angle.

[0051] The horseshoe-shaped microstructure can be transformed into either of the following two structures:

[0052] ① Semi-elliptical microstructure: Construct an ellipse with the side edge as the axis, taking the top and bottom halves in opposite directions;

[0053] like Figure 6 As shown;

[0054] ② Straight Rod Joint Microstructure: Keeping the node distance constant, the horseshoe-shaped microstructure is scaled down proportionally except for its diameter, and both ends are connected to the original nodes with straight rods of equal diameter, such as... Figure 7 As shown.

[0055] In step S2 above, the four-ligament horseshoe-shaped chiral structure can be replaced with a three-ligament horseshoe-shaped chiral structure, that is, three sets of spatial horseshoe-shaped microstructures are constructed with an angle of 120° between them. Correspondingly, in step S4, the horizontal periodic arrangement direction is replaced with a 120° angle, and the resulting square lattice becomes a triangular lattice, as shown below. Figure 3 As shown.

[0056] In step S2 above, the four-ligament horseshoe-shaped chiral structure can be replaced with a six-ligament horseshoe-shaped chiral structure, that is, six sets of spatial horseshoe-shaped microstructures are constructed, with an included angle of 60° between them. Correspondingly, in step S4, the horizontal periodic arrangement direction is replaced with a 60° included angle, and the resulting square lattice becomes a hexagonal lattice, such as... Figure 4 As shown.

[0057] In practical design, a four-ligament chiral structure with a central angle of 90° and a cross-sectional diameter to lattice constant ratio of 0.05 is subjected to finite element analysis. The corresponding stress-strain curves and torsional angle-strain curves are shown below. Figure 5 As shown.

[0058] The metamaterials of this invention can be used to reproduce the nonlinear mechanical properties of biological tissues, such as... Figure 8 As shown, the experimental measurement and finite element analysis results curves for reproducing the nonlinear mechanical properties of the mouse esophageal wall, along with the corresponding octahedral unit cell schematic diagram, explore potential applications for realizing the nonlinear mechanical properties of three-dimensional soft biological tissues.

[0059] The metamaterial of this invention can be used in the design of flexible electronic devices, soft robots, longitudinal wave-rotational wave converters, and biological flaw detection sensors.

[0060] The following points need to be explained:

[0061] (1) The accompanying drawings of the embodiments of the present invention only involve the structures involved in the embodiments of the present invention. Other structures can refer to the general design.

[0062] (2) Where there is no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0063] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A biomimetic mesh metamaterial based on three-dimensional horseshoe microstructures, characterized in that, Obtained by spatial arraying of three-dimensional unit cell structures; The three-dimensional single-cell structure is achieved by connecting the upper and lower vertices of the horseshoe-shaped microstructure along the eight side edges of the regular octahedron in the same bending direction to form a cage-like structure. In the three-dimensional unit cell structure, there are no structures distributed along the transverse edges of the regular octahedron. The upper and lower parts bounded by the transverse edges are regarded as spatial four-ligament chiral units in the longitudinal direction, and are centrally symmetrical about the center point of the regular octahedron. The plane where each horseshoe-shaped microstructure is located has an equal angle with the side surface of the adjacent regular octahedron. The metamaterial design method includes the following steps: S1. Using a set of lateral edges connecting the top and bottom vertices of a regular octahedron as chords, construct spatial horseshoe-shaped microstructures with the same central angle but opposite directions on two planes passing through the lateral edges and perpendicular to each other. The two horseshoe-shaped microstructures are symmetrical about the connected nodes. S2. Construct eight horseshoe-shaped microstructures that are centrally symmetrical about the center point of the octahedron along the eight longitudinal lateral edges of the octahedron: Continue to construct three sets of spatial horseshoe-shaped microstructures according to the method in step S1. The four sets of spatial horseshoe-shaped microstructures are symmetrical about the center of the straight line where the top and bottom vertices of the octahedron are located, and the planes where the four sets of chords are located have an equal angle of 90° between them, forming a four-ligament horseshoe-shaped chiral structure. S3. Set nodal spheres with a diameter of 1.2 times that of horseshoe-shaped microstructures at all nodal positions to form a three-dimensional unit cell; S4. Using the line connecting the three sets of nodes in relative positions of the regular octahedron as the three principal axes, the three-dimensional unit cells are periodically arranged along the three principal axes to form a three-dimensional horseshoe-shaped mesh metamaterial with square lattice.

2. The biomimetic mesh metamaterial based on a three-dimensional horseshoe-shaped microstructure according to claim 1, characterized in that, In step S1, the horseshoe-shaped microstructure changes its shape by altering the corresponding central angle.

3. The biomimetic mesh metamaterial based on a three-dimensional horseshoe-shaped microstructure according to claim 2, characterized in that, The horseshoe-shaped microstructure can be transformed into either of the following two structures: ① Semi-elliptical microstructure: Construct an ellipse with the side edge as the axis, taking the top and bottom halves in opposite directions; ② Straight rod joint microstructure: Keeping the node distance unchanged, the horseshoe-shaped microstructure is scaled down proportionally except for the diameter, and the two ends are connected to the original nodes with straight rods of equal diameter.

4. The biomimetic mesh metamaterial based on a three-dimensional horseshoe-shaped microstructure according to claim 1, characterized in that, In step S2, the four-ligament horseshoe-shaped chiral structure can be replaced with a three-ligament horseshoe-shaped chiral structure, that is, three sets of spatial horseshoe-shaped microstructures are constructed with an angle of 120° between them. Correspondingly, in step S4, the horizontal periodic arrangement direction is replaced with an angle of 120°, and the square lattice formed becomes a triangular lattice.

5. The biomimetic mesh metamaterial based on a three-dimensional horseshoe-shaped microstructure according to claim 1, characterized in that, In step S2, the four-ligament horseshoe-shaped chiral structure can be replaced with a six-ligament horseshoe-shaped chiral structure, that is, six sets of spatial horseshoe-shaped microstructures are constructed with an angle of 60° between them. Correspondingly, in step S4, the horizontal periodic arrangement direction is replaced with an angle of 60°, and the square lattice formed becomes a hexagonal lattice.

6. The biomimetic mesh metamaterial based on a three-dimensional horseshoe-shaped microstructure according to claim 1, characterized in that, The metamaterials are used in the design of flexible electronic devices, soft robots, longitudinal wave-rotational wave converters, and biological flaw detection sensors.

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