Metamaterial structure determination method and device, metamaterial and storage medium

Abstract

The invention provides a metamaterial structure determination method and device, a metamaterial and a storage medium, and the method comprises the steps: carrying out the discretization of a target temperature field, obtaining a plurality of temperature sub-regions, and enabling the temperature of the target temperature field to continuously change in three directions in a space; determining respective temperature variation of the plurality of temperature sub-regions; respective target thermal strain of the metamaterial in three directions is acquired, the metamaterial comprises a plurality of material sub-regions, and the plurality of material sub-regions are in one-to-one correspondence with the plurality of temperature sub-regions; based on the respective target thermal strain of the metamaterial in the three directions and the respective temperature variation of the plurality of temperature sub-regions, determining the respective thermal expansion coefficients of the material sub-regions corresponding to the plurality of temperature sub-regions in the three directions; and determining respective geometric parameters of the plurality of material sub-regions based on respective thermal expansion coefficients of the material sub-regions corresponding to the plurality of temperature sub-regions in the three directions. According to the technical scheme, the gradient metamaterial adaptive to the target temperature field can be determined.

Description

Technical Field

[0001] The present application relates to the field of metamaterial technology, and in particular to a metamaterial structure determination method and device, a metamaterial, and a storage medium. Background Art

[0002] With the development of artificially designed metamaterial structures, metamaterials are widely used in many fields. For example, metamaterials can be used to make satellite brackets in the aerospace field. However, since satellite brackets need to be exposed to non-uniform temperature fields in space, existing metamaterials cannot achieve uniform thermal response in non-uniform temperature fields, causing deformation of satellite brackets and possibly causing satellite deflection. Summary of the invention

[0003] In order to solve the above problems, the present application provides a metamaterial structure determination method and device, a metamaterial, and a storage medium.

[0004] In a first aspect, the present application provides a method for determining a metamaterial structure, comprising: discretizing a target temperature field to obtain a plurality of temperature sub-zones, wherein the temperature of the target temperature field changes continuously in three directions in space; determining the temperature change amount of each of the plurality of temperature sub-zones; obtaining the target thermal strain of the metamaterial in the three directions, the metamaterial comprising a plurality of material sub-zones, and the plurality of material sub-zones corresponding one-to-one to the plurality of temperature sub-zones; determining the thermal expansion coefficients of the material sub-zones corresponding to the plurality of temperature sub-zones in the three directions based on the target thermal strains of the metamaterial in the three directions and the temperature change amounts of the plurality of temperature sub-zones; and determining the geometric parameters of the plurality of material sub-zones based on the thermal expansion coefficients of the material sub-zones corresponding to the plurality of temperature sub-zones in the three directions.

[0005] In combination with the first aspect, the material sub-region includes a unit cell; or, the material sub-region includes a region composed of a plurality of unit cells having the same thermal expansion coefficient.

[0006] In combination with the first aspect, the unit cell is composed of a plurality of quadrangular pyramids, and the bases and hypotenuses of the quadrangular pyramids are made of two materials with different thermal expansion coefficients.

[0007] In combination with the first aspect, the two materials with different thermal expansion coefficients include a first material and a second material, and the thermal expansion coefficient of the first material is greater than the thermal expansion coefficient of the second material; wherein, in the direction in which the target thermal strain of the metamaterial is positive in the three directions, the base of the tetrahedron in this direction is the second material, and the hypotenuse is the first material; in the direction in which the target thermal strain of the metamaterial is negative in the three directions, the base of the tetrahedron in this direction is the first material, and the hypotenuse is the second material.

[0008] In combination with the first aspect, two materials with different thermal expansion coefficients include a first material and a second material, and the thermal expansion coefficient of the first material is greater than the thermal expansion coefficient of the second material; based on the thermal expansion coefficients of the material sub-regions corresponding to each of the multiple temperature sub-regions in three directions, the geometric parameters of the multiple material sub-regions are determined, including: based on the thermal expansion coefficients of the material sub-regions corresponding to each of the multiple temperature sub-regions in three directions, as well as the thermal expansion coefficient of the first material and the thermal expansion coefficient of the second material, the geometric parameters include the base lengths and hypotenuse lengths of the multiple quadrangular pyramids included in each of the multiple material sub-regions.

[0009] In combination with the first aspect, the material sub-region includes vertex-sharing unit cells and / or bottom-sharing unit cells.

[0010] In combination with the first aspect, the target temperature field is discretized to obtain a plurality of temperature sub-zones, including: dividing the target temperature field into a plurality of cubes in space to obtain a plurality of temperature sub-zones, wherein each temperature sub-zone is a uniform target temperature field.

[0011] In a second aspect, the present application also provides a metamaterial, which is prepared according to the above method.

[0012] In a third aspect, the present application also provides a metamaterial structure determination device, comprising: a discrete module, a determination module and an acquisition module; the discrete module is used to discretize the target temperature field to obtain multiple temperature sub-zones, wherein the temperature of the target temperature field changes continuously in three directions in space; the determination module is used to determine the temperature change amount of each of the multiple temperature sub-zones; the acquisition module is used to obtain the target thermal strains of the metamaterial in three directions, the metamaterial includes multiple material sub-zones, and the multiple material sub-zones correspond one-to-one to the multiple temperature sub-zones; the determination module is also used to determine the thermal expansion coefficients of the material sub-zones corresponding to the multiple temperature sub-zones in the three directions based on the target thermal strains of the metamaterial in the three directions and the temperature changes of the multiple temperature sub-zones; the determination module is also used to determine the geometric parameters of the multiple material sub-zones based on the thermal expansion coefficients of the material sub-zones corresponding to the multiple temperature sub-zones.

[0013] In a third aspect, an embodiment of the present application provides an electronic device, comprising: a processor; a memory, the memory being connected to the processor, the memory being used to store a computer program, and the computer program, when executed by the processor, implements the above-mentioned metamaterial structure determination method.

[0014] In a fourth aspect, an embodiment of the present application provides a storage medium having a computer program stored thereon. When the computer program is executed by a processor, the above-mentioned method for determining a metamaterial structure is implemented.

[0015] In a fifth aspect, an embodiment of the present application provides a computer program product, including computer program instructions, which implement the above-mentioned metamaterial structure determination method when executed by a processor.

[0016] Through the above technical solution, in an embodiment of the present application, after determining the geometric parameters of each of the multiple material sub-regions, a gradient metamaterial adapted to the target temperature field can be obtained. The metamaterial includes multiple material sub-regions (for example, unit cells), and the multiple material sub-regions are arranged in a gradient array along three directions. Different material sub-regions have different geometric parameters to adapt to different temperature sub-regions, thereby achieving uniform thermal deformation of the metamaterial in three directions and ensuring the stability of the metamaterial structure in the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flowchart of a method for determining a metamaterial structure provided in an embodiment of the present application.

[0018] Figure 2 It is a schematic diagram of a target temperature field and a discrete temperature field provided in an embodiment of the present application.

[0019] Figure 3 The material distribution patterns of two tetrahedral pyramid structures are shown.

[0020] Figure 4a A schematic diagram of the structure of a common vertex unit cell is shown.

[0021] Figure 4b A schematic diagram of the structure of a unit cell with a common bottom edge is shown.

[0022] Figure 5a The periodic metamaterial obtained by unit cell periodic array is shown.

[0023] Figure 5b The thermal deformation of the periodic metamaterial in the z direction in a gradient temperature field is shown.

[0024] Figure 5c The gradient metamaterial obtained by the unit cell gradient array is shown.

[0025] Figure 5d The thermal deformation of the gradient metamaterial in the z direction in the gradient temperature field is shown.

[0026] Figure 6a A schematic diagram of the structure of a common vertex unit cell is shown.

[0027] Figure 6b A schematic diagram of the structure of a unit cell with a common bottom edge is shown.

[0028] Figure 7a The periodic metamaterial obtained by unit cell periodic array is shown.

[0029] Figure 7b The thermal deformation of the periodic metamaterial in the z direction in a gradient temperature field is shown.

[0030] Figure 7c The gradient metamaterial obtained by the unit cell gradient array is shown.

[0031] Figure 7d The thermal deformation of the gradient metamaterial in the z direction in the gradient temperature field is shown.

[0032] Figure 8 It is a structural schematic diagram of a metamaterial structure determination device provided in one embodiment of the present application.

[0033] Fig. 9 It is a schematic diagram of the structure of an electronic device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] Traditional metamaterials are usually made of a single type of periodic arrangement of unit cells (also called a periodic array). Metamaterials with periodic arrays will undergo non-uniform thermal deformation when placed in a non-uniform temperature field, which will lead to distortion or even failure of the metamaterial. Therefore, metamaterials with periodic arrays cannot adapt to application requirements under gradient temperature fields, which greatly limits the application of metamaterials.

[0036] In view of the above technical problems, the embodiment of the present application provides a method for determining a metamaterial structure, comprising: discretizing a target temperature field to obtain a plurality of temperature sub-regions, wherein the temperature of the target temperature field changes continuously in three directions in space; determining the temperature change amount of each of the plurality of temperature sub-regions; obtaining the target thermal strain of the metamaterial in the three directions, wherein the metamaterial comprises a plurality of material sub-regions, and the plurality of material sub-regions correspond to the plurality of temperature sub-regions one by one; determining the thermal expansion coefficient of the material sub-regions corresponding to the plurality of temperature sub-regions in the three directions based on the target thermal strain of the metamaterial in the three directions and the temperature change amount of each of the plurality of temperature sub-regions; determining the geometric parameters of the plurality of material sub-regions based on the thermal expansion coefficient of the material sub-regions corresponding to the plurality of temperature sub-regions in the three directions. In the embodiment of the present application, after determining the geometric parameters of the plurality of material sub-regions, a metamaterial adapted to the target temperature field can be obtained, wherein the metamaterial comprises a plurality of material sub-regions (e.g., a unit cell), and the plurality of material sub-regions are arranged in a gradient array along three directions, and the geometric parameters of different material sub-regions are different to adapt to different temperature sub-regions, thereby realizing that the metamaterial has uniform thermal deformation in the three directions, and ensuring the stability of the metamaterial structure in the environment.

[0037] Figure 1 FIG. 1 is a flow chart of a method for determining a metamaterial structure provided in an embodiment of the present application. Figure 1 As shown, the method includes the following steps.

[0038] Step S110, discretizing the target temperature field to obtain a plurality of temperature sub-areas.

[0039] In the embodiment of the present application, the temperature of the target temperature field changes continuously in three directions in space. Specifically, the three directions in space can be three coordinate axis directions in the spatial coordinate system, namely, the x direction, the y direction and the z direction. The target temperature field is discretized to obtain a discrete temperature field, and the discrete temperature field includes multiple temperature sub-areas. For example, Figure 2 As shown, the target temperature field is spatially divided into multiple cubes to obtain multiple temperature sub-zones. Each temperature sub-zone is a uniform target temperature field, and the temperatures of adjacent temperature sub-zones may be the same or different, which is not limited in the embodiment of the present application. Optionally, in the embodiment of the present application, when dividing the temperature field, the division may be based on the preset size of the unit cell contained in the metamaterial, so that the size of each temperature sub-zone is the same or similar to the size of one or more unit cells.

[0040] For example, the temperature of the target temperature field is T=G(x, y, z), and the temperatures of the multiple temperature sub-areas after discretization are T ijk=g(i,j,k). Where x, y, z represent the coordinates in the x, y, and z directions in the spatial coordinate system, respectively; i, j, k represent the row, column, and layer number corresponding to each temperature sub-zone, respectively; T ijk Represents the temperature of the temperature sub-zone at the ijk-th position (i.e., the i-th row, the j-th column, the k-th layer).

[0041] Step S120, determining the temperature variation of each of the plurality of temperature sub-zones.

[0042] In the embodiment of the present application, the temperature change refers to the change of the temperature of the temperature sub-area relative to the ambient temperature. The ambient temperature is the temperature of the metamaterial before being placed in the target temperature field, and the ambient temperature can be set to a constant.

[0043] For example, the temperature change can be determined by formula (1):

[0044] ΔT ijk =g(i,j,k)-T a (1);

[0045] Among them, T a is the ambient temperature, ΔT ijk is the temperature change of the temperature sub-zone at the ijk position (i.e., the i-th row, the j-th column, the k-th layer).

[0046] Step S130, obtaining the target thermal strains of the metamaterial in three directions.

[0047] In the embodiment of the present application, the target thermal strain refers to the thermal strain expected by the metamaterial. The target thermal strains of the metamaterial in three directions may be the same or different. For example, the thermal strains of the metamaterial in three directions are the same, all 1×10 -3 Alternatively, the thermal strain of the metamaterial in the three directions is different, for example, 1×10 -3 , and 1.5×10 in the y and z directions -3 In addition, the target thermal strain may be a positive value, that is, the metamaterial achieves positive expansion; or the target thermal strain may be a negative value, that is, the metamaterial achieves negative expansion, which is not limited in the embodiments of the present application.

[0048] In an embodiment of the present application, the metamaterial includes a plurality of material sub-regions, and the plurality of material sub-regions correspond one to one with the temperature sub-regions. In an embodiment of the present application, the material sub-region includes a unit cell; or, the material sub-region includes a region composed of a plurality of unit cells having the same coefficient of thermal expansion. Optionally, the material sub-region includes a common vertex type unit cell and / or a common bottom edge type unit cell. In an embodiment of the present application, the unit cell is composed of a plurality of tetrahedrons (for example, the common vertex type unit cell is composed of six tetrahedrons, and the bottom edges of the six tetrahedrons respectively constitute the six faces of the unit cell), and the bottom edge and hypotenuse of the tetrahedron are two materials having different coefficients of thermal expansion. Optionally, in other embodiments, the unit cell may also be composed of a plurality of triangular pyramids, or other geometric structures, which are not limited by the embodiments of the present application.

[0049] Optionally, the two materials with different thermal expansion coefficients include a first material and a second material, and the thermal expansion coefficient of the first material is greater than the thermal expansion coefficient of the second material. Among them, in the direction where the target thermal strain of the metamaterial is positive in the three directions, the base of the tetrahedron in this direction is the second material, and the hypotenuse is the first material; in the direction where the target thermal strain of the metamaterial is negative in the three directions, the base of the tetrahedron in this direction is the first material, and the hypotenuse is the second material. That is, in the embodiment of the present application, the thermal strain of the metamaterial is regulated by two materials with different thermal expansion coefficients.

[0050] For example, Figure 3 The material distribution modes of two tetrahedral pyramid structures are shown. Among them, the hypotenuse of variant 1 is the first material (i.e. material 1), and the bottom is the second material (i.e. material 2). Since the thermal expansion coefficient of the first material is greater than that of the second material, after heating, the hypotenuse of variant 1 increases more, that is, in the direction perpendicular to the bottom surface, variant 1 has positive expansion ability. The hypotenuse of variant 2 is the second material (i.e. material 2), and the bottom is the first material (i.e. material 1). Since the thermal expansion coefficient of the first material is greater than that of the second material, after heating, the bottom of variant 1 increases more, that is, in the direction perpendicular to the bottom surface, variant 2 has negative expansion ability. The material distribution mode of the tetrahedral pyramid is determined according to the requirements of the actual scenario for positive expansion or negative expansion.

[0051] Step S140 , based on the respective target thermal strains of the metamaterial in the three directions and the respective temperature changes of the plurality of temperature sub-regions, determining the respective thermal expansion coefficients of the material sub-regions corresponding to the plurality of temperature sub-regions in the three directions.

[0052] Optionally, for any of the three directions, the product of the thermal expansion coefficient of each material sub-region and the temperature change of the corresponding temperature sub-region is the target thermal strain of the metamaterial in that direction. Therefore, the thermal expansion coefficient of each material sub-region in that direction can be determined.

[0053] For example, in the x direction, the thermal expansion coefficient of each material sub-region needs to satisfy formula (2):

[0054] α xijk ΔT ijk =ε x , (2),

[0055] Among them, α xijk represents the thermal expansion coefficient of the material sub-region at the ijk position (i.e., row i, column j, layer k) in the x direction, ε x represents the target thermal strain in the x-direction.

[0056] For the y direction, the thermal expansion coefficient of each material sub-region needs to satisfy formula (3):

[0057] α yijk ΔT ijk =ε y (3)

[0058] Among them, α yijk represents the thermal expansion coefficient of the material sub-region at the ijk position (i.e., row i, column j, layer k) in the y direction, ε y represents the target thermal strain in the y direction.

[0059] For the z direction, the thermal expansion coefficient of each material sub-region needs to satisfy formula (4):

[0060] α zijk ΔT ijk =ε z (4)

[0061] Among them, α zijk represents the thermal expansion coefficient of the material sub-region at the ijk position (i.e., row i, column j, layer k) in the z direction, ε z represents the target thermal strain in the z-direction.

[0062] Step S150, determining geometric parameters of each of the plurality of material sub-regions based on the thermal expansion coefficients of the material sub-regions corresponding to each of the plurality of temperature sub-regions in three directions.

[0063] In an embodiment of the present application, each material sub-region includes two materials with different thermal expansion coefficients, that is, a first material and a second material, and the thermal expansion coefficient of the first material is greater than the thermal expansion coefficient of the second material. Specifically, based on the thermal expansion coefficients of the material sub-regions corresponding to each of the multiple temperature sub-regions in three directions, as well as the thermal expansion coefficient of the first material and the thermal expansion coefficient of the second material, the geometric parameters of each of the multiple material sub-regions are determined. Optionally, the geometric parameters include the base length and hypotenuse length of each of the multiple quadrangular pyramids included in each of the multiple material sub-regions.

[0064] Exemplarily, the functional relationship between the thermal expansion coefficient of any material sub-region in the x-direction, y-direction and z-direction and the geometric parameters of the first material and the second material is formula (5):

[0065] α xijk =h xijk (α1,α2,l1,l2),α yijk =h yijk (α1,α2,l1,l2),α zijk =h zijk (α1,α2,l1,l2)(5),

[0066] Wherein, α1 represents the thermal expansion coefficient of the first material, α2 represents the thermal expansion coefficient of the second material, l1 represents the side length of the first material, and l2 represents the side length of the second material.

[0067] Since the thermal expansion coefficient of the first material and the thermal expansion coefficient of the second material are determined values, the length of the side of the first material and the length of the side of the second material can be determined according to formula (5), and the base and the hypotenuse of the tetrahedron are determined according to the arrangement of the first material and the second material, and then the structure of each material sub-region is determined to obtain a metamaterial structure (i.e., a gradient metamaterial). In the embodiment of the present application, after determining the geometric parameters of each of the multiple material sub-regions, a metamaterial adapted to the target temperature field can be obtained. The metamaterial includes multiple material sub-regions (e.g., unit cells), and the geometric parameters of the multiple material sub-regions are different to adapt to different temperature sub-regions. The multiple material sub-regions are arranged in a gradient array along three directions, so that the metamaterial has uniform thermal deformation in three directions, ensuring the stability of the metamaterial structure in the environment.

[0068] The technical solution of the present application is exemplarily described below in conjunction with specific embodiments (for example, Embodiment 1 and Embodiment 2). It can be understood that Embodiment 1 and Embodiment 2 here are only for illustrative purposes and are not intended to limit the scope of protection of the present application.

[0069] Example 1

[0070] In the embodiment of the present application, the design objectives mainly include: the temperature of the target temperature field T = 76-2 (x + y + z), the ambient temperature T a =30℃; the target thermal strain of the metamaterial in three directions is 1×10 -3 , that is, ε x =ε y =ε z =+1×10 -3 ; The length, width and height of the metamaterial are H1=H2=H3=20mm respectively.

[0071] First, if Figure 2As shown, the target temperature field is discretized, and the continuous temperature field in the target temperature field is equivalent to a discrete temperature field. The discrete temperature field includes multiple temperature sub-zones, and the temperature of each temperature sub-zone is T = 76-2 (i + j + k), where i, j, k = 1, 2. Determine the temperature change ΔT of each of the multiple temperature sub-zones ijk =76-2(i+j+k)-30.

[0072] Then, the thermal expansion coefficients of each material sub-region of the metamaterial in three directions are determined. Specifically, for the x direction, α x111 ΔT 111 =α x112 ΔT 112 =…=α x222 ΔT 222 =+1×10 -3 For the y direction, α y111 ΔT 111 =α y112 ΔT 112 =…=α y222 ΔT 222 =+1×10 -3 For the z direction, α z111 ΔT 111 =α z112 ΔT 112 =…=α z222 ΔT 222 =+1×10 -3 .

[0073] In the embodiment of the present application, the material sub-area includes a unit cell, and the unit cell in the metamaterial is designed and the thermal expansion coefficient expression is established. The unit cell is composed of a plurality of tetrahedral pyramids (for example, 6 tetrahedral pyramids). According to the requirements of the design target, the metamaterial has positive expansion capabilities in three directions. Therefore, the material distribution method of the tetrahedral pyramid structure is selected. Figure 3 Variant 1 in the example is rotated and / or symmetric, for example, the tetrahedron is rotated 90° and 180° around the vertex in space to obtain a common vertex unit cell, such as Figure 4a In other embodiments, variant 1 can also be used to obtain a common bottom edge unit cell, such as Figure 4b shown.

[0074] by Figure 4a Taking the common vertex unit cell as an example, the thermal expansion coefficient expression is formula (6):

[0075]

[0076] Among them, α x , α y , α zare the thermal expansion coefficients of the unit cell in the x, y, and z directions, respectively.

[0077] In addition, in order to ensure the uniformity of the initial shape of the gradient metamaterial, the dimensions of each unit cell in three directions are fixed, namely:

[0078]

[0079] In the embodiment of the present application, the first material is selected as Al-7075, and the thermal expansion coefficient α1=24×10 -6 ℃, the second material is Invar, thermal expansion coefficient α1=2.4×10 -6 ℃.

[0080] Therefore, the geometric parameters of different material sub-regions can be determined according to the above formula, and then the metamaterial structure (ie, gradient metamaterial) can be determined, as shown in Table 1 and Table 2.

[0081] Table 1 shows the geometric parameters (l1, l2) of the material sub-area of ​​the first layer, in mm.

[0082]

[0083] Table 2 shows the geometric parameters (l1, l2) of the material sub-area of ​​the second layer, in mm.

[0084]

[0085] Figure 5a The figure shows a periodic metamaterial obtained by a periodic array of unit cells, that is, each unit cell is exactly the same. Figure 5b The thermal deformation of the periodic metamaterial in the z direction in a gradient temperature field is shown. Figure 5c The figure shows the gradient metamaterial obtained by the unit cell gradient array, that is, the geometric parameters of each unit cell are different. Figure 5d Figure 2 shows the thermal deformation of the gradient metamaterial in the z direction in the gradient temperature field. Figure 5b and 5d As shown in Figure 2, the thermal deformation of the periodic material in the gradient temperature field is non-uniform, while the gradient metamaterial has uniform thermal deformation in the gradient temperature field, and the thermal strain is 1×10 -3 , which meets the design goals.

[0086] Example 2

[0087] In the embodiment of the present application, the design objectives mainly include: the temperature of the target temperature field T = 76-2 (x + y + z), the ambient temperature T a =30℃; the target thermal strain of the metamaterial in three directions is -1×10 -3 , that is, ε x =ε y =ε z=-1×10 -3 ; The length, width and height of the metamaterial are H1=H2=H3=20mm respectively.

[0088] First, if Figure 2 As shown, the target temperature field is discretized, and the continuous temperature field in the target temperature field is equivalent to a discrete temperature field. The discrete temperature field includes multiple temperature sub-zones, and the temperature of each temperature sub-zone is T = 76-2 (i + j + k), where i, j, k = 1, 2. Determine the temperature change ΔT of each of the multiple temperature sub-zones ijk =76-2(i+j+k)-30.

[0089] Then, the thermal expansion coefficients of each material sub-region of the metamaterial in three directions are determined. Specifically, for the x direction, α x111 ΔT 111 =α x112 ΔT 112 =…=α x222 ΔT 222 =-1×10 -3 For the y direction, α y111 ΔT 111 =α y112 ΔT 112 =…=α y222 ΔT 222 =-1×10 -3 For the z direction, α z111 ΔT 111 =α z112 ΔT 112 =…=α z222 ΔT 222 =-1×10 -3 .

[0090] In the embodiment of the present application, the material sub-area includes a unit cell, and the unit cell in the metamaterial is designed and the thermal expansion coefficient expression is established. The unit cell is composed of a plurality of tetrahedral pyramids (for example, 6 tetrahedral pyramids). According to the requirements of the design target, the metamaterial has negative expansion capabilities in three directions. Therefore, the material distribution method of the tetrahedral pyramid structure is selected. Figure 3 Variant 2 in the example is rotated and / or symmetric, for example, the tetrahedron is rotated 90° and 180° around the vertex in space to obtain a common vertex unit cell, such as Figure 6a In other embodiments, variant 1 can also be used to obtain a common bottom edge unit cell, such as Figure 6b shown.

[0091] by Figure 6a Taking the common vertex unit cell as an example, the thermal expansion coefficient expression is formula (6):

[0092]

[0093] Among them, α x , α y , α z are the thermal expansion coefficients of the unit cell in the x, y, and z directions, respectively.

[0094] In addition, in order to ensure the uniformity of the initial shape of the gradient metamaterial, the dimensions of each unit cell in three directions are fixed, namely:

[0095]

[0096] In the embodiment of the present application, the first material is selected as Al-7075, and the thermal expansion coefficient α1=24×10 -6 ℃, the second material is Invar, thermal expansion coefficient α1=2.4×10 -6 ℃.

[0097] Therefore, the geometric parameters of different material sub-regions can be determined according to the above formula, and then the metamaterial structure (ie, gradient metamaterial) can be determined, as shown in Table 3 and Table 4.

[0098] Table 3 shows the geometric parameters (l1, l2) of the material sub-area of ​​the first layer, in mm.

[0099]

[0100] Table 4 shows the geometric parameters (l1, l2) of the material sub-area of ​​the second layer, in mm.

[0101]

[0102] Figure 7a The figure shows a periodic metamaterial obtained by a periodic array of unit cells, that is, each unit cell is exactly the same. Figure 7b The thermal deformation of the periodic metamaterial in the z direction in a gradient temperature field is shown. Figure 7c The figure shows the gradient metamaterial obtained by the unit cell gradient array, that is, the geometric parameters of each unit cell are different. Figure 7d Figure 2 shows the thermal deformation of the gradient metamaterial in the z direction in the gradient temperature field. Figure 7b and 7d As shown in Figure 2, the thermal deformation of the periodic material in the gradient temperature field is non-uniform, while the gradient metamaterial has uniform thermal deformation in the gradient temperature field, and the thermal strain is -1×10 -3 , which meets the design goals.

[0103] In a second aspect, the present application also provides a metamaterial, which is prepared according to the method in the above embodiment. The metamaterial is a gradient metamaterial, that is, the metamaterial includes multiple material sub-regions, and different material sub-regions have different geometric parameters.

[0104] In a third aspect, an embodiment of the present application also provides a metamaterial structure determination device.

[0105] Figure 8 Schematic diagram of the structure of a metamaterial structure determination device provided by an embodiment of the present application. Figure 8 As shown, the metamaterial structure determination device includes a discrete module 810 , a determination module 820 and an acquisition module 830 .

[0106] The discretization module 810 is used to discretize the target temperature field to obtain a plurality of temperature sub-areas, wherein the temperature of the target temperature field changes continuously in three directions in space.

[0107] Optionally, the discrete module 810 is used to divide the target temperature field into a plurality of cubes in space to obtain a plurality of temperature sub-regions, wherein each temperature sub-region is a uniform target temperature field.

[0108] The determination module 820 is used to determine the temperature variation of each of the plurality of temperature sub-regions.

[0109] The acquisition module 830 is used to acquire the target thermal strains of the metamaterial in three directions. The metamaterial includes a plurality of material sub-regions, and the plurality of material sub-regions correspond to a plurality of temperature sub-regions one by one.

[0110] The determination module 820 is further configured to determine the thermal expansion coefficients of the material sub-regions corresponding to the multiple temperature sub-regions in the three directions, based on the target thermal strains of the metamaterial in the three directions and the temperature changes of the multiple temperature sub-regions.

[0111] The determination module 820 is further configured to determine geometric parameters of each of the plurality of material sub-regions based on the thermal expansion coefficients of the material sub-regions corresponding to each of the plurality of temperature sub-regions in three directions.

[0112] Optionally, the determination module 820 is further used to determine the geometric parameters of each of the multiple material sub-regions based on the thermal expansion coefficients of the material sub-regions corresponding to each of the multiple temperature sub-regions in three directions, and the thermal expansion coefficient of the first material and the thermal expansion coefficient of the second material.

[0113] The specific working principle and benefits of the metamaterial structure determination device provided in the embodiment of the present application are similar to the specific working principle and benefits of the metamaterial structure determination method provided in the embodiment of the present application, and will not be repeated here.

[0114] Below, reference Fig. 9 To describe an electronic device according to an embodiment of the present application. Fig. 9 It is a schematic diagram of the structure of an electronic device provided in one embodiment of the present application.

[0115] like Fig. 9As shown, the electronic device 900 includes one or more processors 901 and a memory 902 .

[0116] The processor 901 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device 900 to perform desired functions.

[0117] The memory 902 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, a random access memory (RAM) and / or a cache memory (cache), etc. The non-volatile memory may include, for example, a read-only memory (ROM), a hard disk, a flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 901 may run the program instructions to implement the metamaterial structure determination method of each embodiment of the present application described above and / or other desired functions. Various contents such as target temperature field, target thermal strain, etc. may also be stored in the computer-readable storage medium.

[0118] In one example, the electronic device 900 may further include: an input device 903 and an output device 904 , and these components are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0119] The input device 903 may include, for example, a keyboard, a mouse, etc.

[0120] The output device 904 can output various information to the outside, including the temperature variation of the temperature sub-zone, the geometric parameters of the material sub-zone, etc. The output device 904 can include, for example, a display, a speaker, a printer, a communication network and its connected remote output device, etc.

[0121] Of course, to simplify, Fig. 9 Only some of the components related to the present application in the electronic device 900 are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, according to specific application situations, the electronic device 900 may also include any other appropriate components.

[0122] In addition to the above-mentioned methods and devices, an embodiment of the present application may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to execute the steps of the metamaterial structure determination method according to various embodiments of the present application described above in this specification.

[0123] The computer program product may be written in any combination of one or more programming languages ​​to write program codes for performing the operations of the embodiments of the present application, including object-oriented programming languages, such as Java, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as an independent software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0124] In addition, an embodiment of the present application may also be a computer-readable storage medium having computer program instructions stored thereon, and when the computer program instructions are executed by a processor, the processor executes the steps of the method for determining the metamaterial structure according to various embodiments of the present application described above in this specification.

[0125] The computer readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can include, for example, but is not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0126] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0127] The block diagrams of the devices, apparatuses, equipment, and systems involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.

[0128] It should also be noted that in the apparatus, device and method of the present application, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0129] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0130] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A method for determining a metamaterial structure, characterized in that: include: Discretizing the target temperature field to obtain a plurality of temperature sub-areas, wherein the temperature of the target temperature field changes continuously in three directions in space; Determining a temperature change of each of the plurality of temperature sub-regions; Obtaining target thermal strains of the metamaterial in each of the three directions, wherein the metamaterial includes a plurality of material sub-regions, and the plurality of material sub-regions correspond one-to-one to the plurality of temperature sub-regions; Determine the thermal expansion coefficients of the material sub-regions corresponding to the multiple temperature sub-regions in the three directions based on the target thermal strains of the metamaterial in the three directions and the temperature changes of the multiple temperature sub-regions; Based on the thermal expansion coefficients of the material sub-regions corresponding to the temperature sub-regions in the three directions, the geometric parameters of the material sub-regions are determined.

2. The method according to claim 1, characterized in that: The material sub-region includes a unit cell; or, the material sub-region includes a region composed of a plurality of unit cells having the same thermal expansion coefficient.

3. The method according to claim 2, characterized in that The unit cell is composed of a plurality of quadrangular pyramids, and the base and the hypotenuse of the quadrangular pyramid are made of two materials with different thermal expansion coefficients.

4. The method according to claim 3, characterized in that: The two materials with different thermal expansion coefficients include a first material and a second material, and the thermal expansion coefficient of the first material is greater than the thermal expansion coefficient of the second material; Among them, in the direction where the target thermal strain of the metamaterial is positive among the three directions, the base of the tetrahedron in the direction is the second material, and the hypotenuse is the first material; in the direction where the target thermal strain of the metamaterial is negative among the three directions, the base of the tetrahedron in the direction is the first material, and the hypotenuse is the second material.

5. The method according to claim 3, characterized in that: The two materials with different thermal expansion coefficients include a first material and a second material, and the thermal expansion coefficient of the first material is greater than the thermal expansion coefficient of the second material; and determining the geometric parameters of the plurality of material sub-regions based on the thermal expansion coefficients of the material sub-regions corresponding to the plurality of temperature sub-regions in the three directions, respectively, includes: Based on the thermal expansion coefficients of the material sub-regions corresponding to each of the multiple temperature sub-regions in the three directions, as well as the thermal expansion coefficient of the first material and the thermal expansion coefficient of the second material, the geometric parameters of each of the multiple material sub-regions are determined; wherein the geometric parameters include the base lengths and hypotenuse lengths of the multiple quadrangular pyramids included in each of the multiple material sub-regions.

6. The method according to claim 1, characterized in that The material sub-regions include vertex-sharing unit cells and / or bottom-sharing unit cells.

7. The method according to claim 1, characterized in that The discretizing the target temperature field to obtain a plurality of temperature sub-areas includes: dividing the target temperature field into a plurality of cubes in the space to obtain the plurality of temperature sub-areas, wherein each of the temperature sub-areas is a uniform target temperature field.

8. A metamaterial, characterized in that: The metamaterial is prepared according to the method according to any one of claims 1 to 7.

9. A metamaterial structure determination device, characterized in that: include: A discrete module, used for discretizing the target temperature field to obtain a plurality of temperature sub-areas, wherein the temperature of the target temperature field changes continuously in three directions in space; A determination module, used to determine the temperature change of each of the plurality of temperature sub-areas; An acquisition module, configured to acquire target thermal strains of the metamaterial in the three directions, wherein the metamaterial includes a plurality of material sub-regions, and the plurality of material sub-regions correspond one-to-one to the plurality of temperature sub-regions; The determination module is further used to determine the thermal expansion coefficients of the material sub-regions corresponding to the multiple temperature sub-regions in the three directions, based on the target thermal strains of the metamaterial in the three directions and the temperature changes of the multiple temperature sub-regions; The determination module is further configured to determine the respective geometric parameters of the plurality of material sub-regions based on the respective thermal expansion coefficients of the material sub-regions corresponding to the plurality of temperature sub-regions in the three directions.

10. A storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by the processor, the method for determining the metamaterial structure according to any one of claims 1 to 7 is implemented.

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