Structure optimization method of magnetostatic shielding box

Abstract

The invention relates to a structure optimization method of a magnetostatic shielding box. The method comprises the following steps: constructing a magnetostatic shielding box with a multilayer cube laminated structure; performing isovolumetric transformation processing to obtain the equivalent sphere radius of the nth shielding layer of the magnetostatic shielding box; constructing a target function according to the structural parameters of the shielding layer; and establishing an equivalence relation between the thickness of each shielding layer of the magnetostatic shielding box and the thickness of the corresponding equivalent sphere shielding layer, and introducing the thickness equivalence relation into a target function so as to uniformly map the structural parameters of the shielding layers into an equivalent sphere model for shielding effectiveness calculation. The target function can reflect the shielding effectiveness change trend under different thickness combinations; and performing global optimization on the target function by adopting a particle swarm optimization algorithm, searching the number of shielding layers with the maximum shielding effectiveness and the thickness and volume parameters of each layer, determining the number of shielding layers with the maximum shielding effectiveness and the thickness and volume parameters of each layer according to a search result, and performing structure optimization on the magnetostatic shielding box.

Description

Technical Field

[0001] This invention relates to the field of magnetic shielding technology, and in particular to a method for optimizing the structure of a static magnetic shielding box. Background Technology

[0002] With the widespread application of high-precision equipment in fields such as electronics and medicine, these devices place high demands on the stability of the magnetic environment. Microelectronic automotive instruments, transformers, sensors, and miniature components within precision electronic equipment require magnetic field shielding. Furthermore, precision equipment such as MRI scanners and magnetocardiographs have extremely high requirements for magnetic field stability; even minor magnetic field interference can lead to blurred images or diagnostic errors, affecting medical outcomes. Therefore, magnetically shielded boxes with excellent shielding effects are of paramount importance.

[0003] Currently, most magnetic shielding boxes use a single material for their shielding layer, resulting in a heavy shielding layer that is prone to saturation in strong magnetic fields. Commonly used shielding materials have limited shielding effectiveness in strong magnetic fields and are easily saturated. For example, commonly used materials such as permalloy and silicon steel have insufficient relative permeability and saturation magnetic induction, and their density is also very high. The effectiveness of traditional shielding boxes in verifying magnetic field shielding relies on experimental testing. Achieving the optimal shielding structure depends on a large amount of experimental data, which is inefficient and costly. Therefore, it is necessary to develop a structural optimization method that can quickly, efficiently, and cost-effectively optimize the structure of the shielding box and obtain a magnetic shielding box with better magnetic shielding performance based on the optimized structure. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the prior art by proposing a structural optimization method for a static magnetic shielding box.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a method for optimizing the structure of a static magnetic shielding box, the method comprising:

[0006] A multi-layered magnetically shielded box is constructed. The magnetically shielded box has a cubic structure and includes a cavity and n shielding layers from the inside out, where n is an odd number greater than or equal to 3. From the inside out, the odd-numbered shielding layers are high relative permeability alloy layers, and the even-numbered shielding layers are low-density non-magnetic material layers. The n shielding layers are multiple concentrically arranged hollow cubic structures.

[0007] Each shielding layer is subjected to an equal volume transformation to obtain the equivalent sphere radius (r) of the nth shielding layer. n );

[0008] An objective function is constructed based on the structural parameters of the shielding layer, wherein the objective function uses the thickness and volume of each shielding layer as variable parameters; the structural parameters of the shielding layer include: the thickness (t) of the nth shielding layer. n ), the volume of the nth shielding layer (v)n ), the equivalent sphere radius (r n ) of the nth shielding layer, the number of shielding layers (n), and the relative permeability (μ n ) of the material of the nth shielding layer;

[0009] An equivalence relationship between the thickness of each shielding layer of the static magnetic shielding box and the thickness of the corresponding equivalent sphere shielding layer is established, and the thickness equivalence relationship is introduced into the objective function, so as to uniformly map the structural parameters of the shielding layers to the equivalent sphere model for shielding effectiveness calculation, thereby enabling the objective function to reflect the shielding effectiveness variation trend under different thickness combinations;

[0010] Based on the set constraint conditions and parameter boundaries, a particle swarm optimization algorithm is used to globally optimize the objective function, search for the shielding layer number, thickness and volume parameters of each layer with the maximum shielding effectiveness, and determine the shielding layer number, thickness and volume parameters of each layer with the maximum shielding effectiveness according to the search results, and perform structural optimization on the static magnetic shielding box.

[0011] Preferably, the material of the high relative permeability alloy layer is at least one of permalloy, super-permalloy, iron-silicon alloy, iron-cobalt alloy, iron-based amorphous alloy, and nanocrystalline alloy with a relative permeability greater than or equal to 50,000;

[0012] The material of the low-density non-magnetic material layer is at least one of polymethyl methacrylate (PMMA), polypropylene (PP), polycarbonate (PC), polyether ether ketone (PEEK), carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), alumina ceramic material, and silicon nitride ceramic material with a density less than 2 g / cm 3 .

[0013] Preferably, the equal-volume transformation processing is performed on each shielding layer to obtain the equivalent sphere radius (r n ) of the nth shielding layer, and specifically includes:

[0014] The static magnetic shielding box with a multi-layer structure is subjected to equal-volume transformation processing with a multi-layer sphere shielding box, so that V n = v n , and the equivalent sphere radius r n of the nth shielding layer is obtained. Wherein, V n is the volume of the nth layer of the multi-layer sphere shielding box, and v n is the volume of the nth layer of the static magnetic shielding box with a multi-layer structure.

[0015] Further preferably, the objective function SE' is constructed according to the structural parameters of the shielding layers, and specifically includes:

[0016] Based on the shielding effectiveness SE of the multi-layer spherical shielding box and the equivalent spherical radius R of the nth shielding layer. n ’ And the volume difference ΔV between the nth shielding layer and the (n-1)th shielding layer n Construct the objective function SE'; where the shielding effectiveness of the multi-layer spherical shielding box is... μ n T represents the relative permeability of the nth shielding layer of a multi-layered spherical shielded box. n R is the thickness of the nth shielding layer of the multi-layer spherical shielding box. n Let ΔV be the inner radius of the nth shielding layer of the multi-layer spherical shielding box. n Let ΔV be the volume difference between the nth and (n-1)th shielding layers of the multi-layer spherical shielding box. n =V n -V n-1 =v n -v n-1 ;

[0017] The objective function SE' is:

[0018]

[0019] More preferably, establishing the equivalence relationship between the thickness of each shielding layer of the static magnetic shielding box and the thickness of the corresponding equivalent spherical shielding layer, and incorporating this thickness equivalence relationship into the objective function to uniformly map the structural parameters of the shielding layers to the equivalent spherical model for shielding effectiveness calculation, specifically includes:

[0020] First, establish the equivalence relationship between the thickness t2 of the second shielding layer of the static magnetic shielding box and the thickness T2 of the equivalent spherical shielding layer:

[0021] Will Generalization, establishing the thickness T of the equivalent spherical shielding layer. n The thickness t of each shielding layer in the corresponding static magnetic shielding box n The equivalence relation between them:

[0022] Will The objective function SE' is introduced to uniformly map the structural parameters of the shielding layer of the magnetically static shielding box to an equivalent sphere model for calculating the shielding effectiveness of the magnetically static shielding box.

[0023] Where, μ n The relative permeability of the nth shielding layer in a multi-layered magnetically shielded box is given by π, where π is pi and t is t. n The thickness of the nth equivalent spherical shielding layer of the multi-layered magnetically shielded box is given.

[0024] v n Volume of the nth shielding layer of the multi-layered magnetically shielding box.

[0025] Preferably, the particle swarm optimization algorithm is used to globally optimize the objective function based on the set constraints and parameter boundaries, to search for the shielding layer number, thickness and volume parameters of each layer with the maximum shielding effectiveness, and the structure of the magnetically shielding box is optimized according to the shielding layer number, thickness and volume parameters of each layer with the maximum shielding effectiveness determined through the search results, specifically including:

[0026] The range of the number n of the shielding layers of the magnetically shielding box is set, and the particle swarm optimization algorithm is used to globally optimize the objective function, to search for the number n of the shielding layers with the maximum shielding effectiveness SE' and the thickness t n and volume parameters v n of each layer; and the structure of the magnetically shielding box is optimized according to n, t n and v n .

[0027] In the particle swarm optimization algorithm, the number N of particles is determined through testing, the maximum number of iterations iter max corresponding to the number n of the shielding layers is set, the inertia weight w is determined using the linear decreasing method, and the formula of the inertia weight w is:

[0028] wherein w max is the maximum inertia weight, w min is the minimum inertia weight, iter is the actual number of iterations when converging, the convergence precision threshold ∈ is 1e -3 , and the spatial boundary of t n is searched.

[0029] Preferably, the structure optimization method further includes simulation verification; the simulation verification includes modeling and simulation verification of the number of the shielding layers with the maximum shielding effectiveness and the thickness and volume parameters of each layer determined using the finite element method.

[0030] Further preferably, the finite element method includes a multi-physical field simulation software (COMSOL Multiphysics).

[0031] In a second aspect, the application provides a magnetically shielding box, which is a cubic structure and sequentially includes a cavity and n layers of shielding layers from inside to outside, wherein n is an odd number greater than or equal to 3; the n layers of shielding layers include odd-numbered layers of high relative permeability alloy layers and even-numbered layers of low-density non-magnetic material layers from inside to outside; and the n layers of shielding layers are a plurality of concentric hollow cubic structures.

[0032] The structural parameters of the static magnetic shielding box are obtained by the structural optimization method in any one of claims 1-8: the number n of layers of the shielding layer, the thickness t of each layer of the shielding layer n , and the volume v of the cube formed by each layer of the shielding layer n .

[0033] Preferably, the material of the high relative permeability alloy layer is at least one of a permalloy, a super-permalloy, a ferrosilicon alloy, a ferrocobalt alloy, a ferro-based amorphous alloy, and a nanocrystalline alloy, with a relative permeability greater than or equal to 50,000.

[0034] The material of the low-density non-magnetic material layer is at least one of polymethyl methacrylate (PMMA), polypropylene (PP), polycarbonate (PC), polyether ether ketone (PEEK), carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), aluminum oxide ceramic material, and silicon nitride ceramic material, with a density less than 2 g / cm 3 .

[0035] The embodiment of the present application provides a structural optimization method of a static magnetic shielding box, which first constructs a static magnetic shielding box with a multi-layer cube structure; then performs an equivalent volume transformation on each layer of the shielding layer of the static magnetic shielding box to obtain an equivalent spherical radius (r n ) of the nth layer of the shielding layer; then constructs an objective function according to the structural parameters of the shielding layer, including the thickness t n , the volume v n , the equivalent spherical radius r n , the number n of layers, and the relative permeability μ n , the objective function taking the thickness t n and the volume v n of each layer of the shielding layer as variable parameters; then establishes an equivalence relationship between the thickness of each layer of the shielding layer of the static magnetic shielding box and the thickness of the corresponding equivalent spherical shielding layer, and introduces the thickness equivalence relationship into the objective function, so as to uniformly map the structural parameters of the shielding layer to the equivalent spherical model for shielding effectiveness calculation, so that the objective function can reflect the shielding effectiveness variation trend under different thickness combinations; finally, based on the set constraint conditions and parameter boundaries, the particle swarm optimization algorithm is used to globally optimize the objective function, to search for the number of layers of the shielding layer with the maximum shielding effectiveness, and the thickness and volume parameters of each layer, and to determine the number of layers of the shielding layer with the maximum shielding effectiveness, and the thickness and volume parameters of each layer according to the search results, to optimize the structure of the static magnetic shielding box. The determined number of layers of the shielding layer with the maximum shielding effectiveness, and the thickness and volume parameters of each layer can be modeled and simulated by the finite element method for verification.

[0036] The structural optimization method provided by the embodiment of the present application can more quickly and effectively obtain the optimal structural parameters of the static magnetic shielding box, while reducing errors and improving efficiency.

[0037] The static magnetic shielding box provided by the embodiment of the present application can be widely applied in the fields of electronics, medical treatment and the like due to the optimal structure parameters obtained by the structure optimization method provided by the present application, the multilayered structure of the high relative magnetic permeability alloy layer and the low-density non-magnetic material layer, the reduced weight of the shielding layer, the reduced risk of single-layer magnetic shielding saturation and the improved magnetic environment stability. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The flow chart of the structure optimization method of the static magnetic shielding box provided by the embodiment of the present application.

[0039] Figure 2 The three-dimensional structure schematic diagram of the static magnetic shielding box provided by the embodiment of the present application.

[0040] Figure 3 The top view sectional schematic diagram of the static magnetic shielding box provided by the embodiment of the present application.

[0041] Figure 4 The comparison diagram of the predicted value of the structure optimization method provided by the embodiment 1 and the COMSOL Multiphysics simulation actual value. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present application.

[0043] The technical scheme of the present application will be further described in detail below with reference to the drawings and embodiments.

[0044] The embodiment of the present application provides a structure optimization method of a static magnetic shielding box, as shown in the figure, specifically comprising the following steps: Figure 1

[0045] Step 110, a static magnetic shielding box with a multilayer structure is constructed, the static magnetic shielding box is a cubic structure, and the static magnetic shielding box comprises a cavity and n layers of shielding layers from inside to outside, n is an odd number greater than or equal to 3; the n layers of shielding layers are arranged from inside to outside, and the odd layers are high relative magnetic permeability alloy layers, and the even layers are low-density non-magnetic material layers; the n layers of shielding layers are a plurality of hollow cubic structures arranged concentrically.

[0046] The material of the high relative magnetic permeability alloy layer is at least one of permalloy, super-permalloy, iron-silicon alloy, iron-cobalt alloy, amorphous alloy, iron-aluminum alloy and nanocrystalline alloy with a relative magnetic permeability greater than or equal to 50000.​

[0047] The material of the low-density non-magnetic material layer is at least one of polymethyl methacrylate (PMMA), polypropylene (PP), polycarbonate (PC), polyether ether ketone (PEEK), carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), alumina ceramic material, and silicon nitride ceramic material, and the density of the low-density non-magnetic material layer is less than 2 g / cm 3

[0048] A three-dimensional structure diagram of the multi-layer structure of the static magnetic shielding box constructed by the application is shown in the figure, and the figure only shows a three-layer shielding layer structure. Figure 2 As can be seen, the static magnetic shielding box constructed by the application includes a cavity, a first shielding layer, a second shielding layer, and a third shielding layer from inside to outside, the first shielding layer and the third shielding layer are high-permeability alloy layers, and the second shielding layer is a low-density non-magnetic material layer, forming a sandwich structure.

[0049] In step 120, each shielding layer is subjected to an equal-volume transformation process to obtain an equivalent spherical radius (r n ) of the nth shielding layer.

[0050] Specifically, the multi-layer structure of the static magnetic shielding box and the multi-layer spherical shielding box are subjected to an equal-volume transformation process, so that V n =v n , and an equivalent spherical radius r n of the nth shielding layer is obtained. Wherein, V n is the volume of the nth layer of the multi-layer spherical shielding box, and v n is the volume of the nth layer of the multi-layer structure of the static magnetic shielding box.

[0051] In step 130, a target function is constructed according to the structure parameters of the shielding layer, and the thickness and volume of each shielding layer are used as variable parameters.

[0052] Wherein, the structure parameters of the shielding layer of the static magnetic shielding box include the thickness (t n ) of the nth shielding layer, the volume (v n ) of the nth shielding layer, the equivalent spherical radius (r n ) of the nth shielding layer, the number of shielding layers (n), and the relative permeability (μ n ) of the material of the nth shielding layer.

[0053] Specifically, the process of constructing the target function according to the structure parameters of the shielding layer is as follows: based on the shielding effectiveness SE of the multi-layer spherical shielding box and the equivalent spherical radius r​n and the volume (v n ) of the n-1th shielding layer n-1 ) of the n-1th shielding layer n Construct a target function SE';

[0054] Wherein, the shielding effectiveness SE of the multi-layer spherical shielding box is:

[0055]

[0056] μ n is the relative permeability of the n-th shielding layer of the multi-layer spherical shielding box, T n is the thickness of the n-th shielding layer of the multi-layer spherical shielding box, R n is the inner radius of the n-th shielding layer of the multi-layer spherical shielding box, △V n is the volume difference between the n-th shielding layer and the n-1th shielding layer of the multi-layer spherical shielding box, △V n = V n -V n-1 = v n -v n-1 ;

[0057] The target function SE' is:

[0058]

[0059] In step 140, the equivalence relationship between the thickness of each shielding layer of the static magnetic shielding box and the thickness of the corresponding equivalent spherical shielding layer is established, and the thickness equivalence relationship is introduced into the target function, so as to map the structural parameters of the shielding layer to the equivalent spherical model for shielding effectiveness calculation, so that the target function can reflect the shielding effectiveness change trend under different thickness combinations.

[0060] Specifically, first, the equivalence relationship between the thickness t2 of the second shielding layer of the static magnetic shielding box and the thickness T2 of the equivalent spherical shielding layer is established: the top view of the static magnetic shielding box provided by the application is shown in FIG. 1, the innermost layer of the static magnetic shielding box is a cavity, d1 and d2 are the side lengths of the first and second cubic shielding layers, R1 and R2 are the radii of the first and second equivalent spheres, t2 and T2 are the thicknesses of the second cubic shielding layer and the second equivalent spherical shielding layer, respectively, and the following is obtained: Figure 3

[0061]

[0062] The following can be obtained: ​​​The second layer of the static magnetic shielding box is obtained by arranging the thickness t2 of the shielding layer and the thickness T2 of the equivalent spherical shielding layer, and the equivalence relationship between them is obtained:

[0063]

[0064] The generalization is established between the thickness T of each layer of the equivalent spherical shielding layer and the thickness t of each layer of the corresponding static magnetic shielding box: n n The equivalence relationship between them is obtained: The generalization in the application refers to the equivalence relationship between the thickness T of each layer of the equivalent spherical shielding layer and the thickness t of each layer of the corresponding static magnetic shielding box: The equivalence relationship between them is obtained by analogy: n n The equivalence relationship between them is obtained:

[0065] The target function SE' is introduced into the target function SE' to uniformly map the structural parameters of the shielding layer of the static magnetic shielding box to the equivalent spherical model for calculating the shielding effectiveness of the static magnetic shielding box:

[0066] Wherein, μ n is the relative magnetic permeability of the nth layer of the shielding layer of the multi-layer structure static magnetic shielding box, π is the circular constant, t n is the thickness of the nth layer of the equivalent spherical shielding layer of the multi-layer structure static magnetic shielding box,

[0067] v n is the volume of the nth layer of the shielding layer of the multi-layer structure static magnetic shielding box.

[0068] Step 150, based on the set constraint condition and parameter boundary, the particle swarm optimization algorithm is used to globally optimize the target function, search the shielding layer number and the thickness and volume parameters of each layer with the maximum shielding effectiveness, and according to the search result, the shielding layer number and the thickness and volume parameters of each layer with the maximum shielding effectiveness are determined, and the structure of the static magnetic shielding box is optimized;

[0069] The specific process is: setting the range of the number n of the shielding layer of the static magnetic shielding box, using the particle swarm optimization algorithm to globally optimize the target function, searching the shielding layer number n and the thickness t n and volume parameters v n of each layer with the maximum shielding effectiveness SE'; according to n, t n and v n , the structure of the static magnetic shielding box is optimized.

[0070] ​​Wherein, when the particle swarm optimization algorithm is used, the number of particles N is obtained by testing, and the maximum iteration number iter corresponding to the number of layers n is set max The inertia weight w is determined using a linear decreasing method, and the formula of the inertia weight w is:

[0071] Wherein, w max is the maximum inertia weight, w min is the minimum inertia weight, iter is the actual iteration number when convergence, and the convergence accuracy threshold value is 1e -3 The space boundary of t n is searched.

[0072] In addition, the structure optimization method provided by the embodiment of the application further comprises simulation verification; the determined shielding layer number, thickness and volume parameters of each layer with the maximum shielding effectiveness are modeled and simulated for verification using a finite element method. The finite element method includes but is not limited to using a multi-physical field simulation software (COMSOL Multiphysics) to model and simulate the determined shielding layer number, thickness and volume parameters of each layer when the shielding effectiveness of the static magnetic shielding box is the maximum.

[0073] The embodiment of the application further provides a static magnetic shielding box with a multi-layer cubic structure, which comprises cavities and n layers of shielding layers from inside to outside, and n is an odd number greater than or equal to 3; from inside to outside, the n layers of shielding layers are an odd number of high relative permeability alloy layers and an even number of low-density non-magnetic material layers; the n layers of shielding layers are a plurality of concentric hollow cubic structures. Wherein, the material of the high relative permeability alloy layer is at least one of permalloy, super-permalloy, iron-silicon alloy, iron-cobalt alloy, amorphous alloy, iron-aluminum alloy and nanocrystalline alloy with a relative permeability greater than or equal to 50000; the material of the low-density non-magnetic material layer is at least one of polymethyl methacrylate (PMMA), polypropylene (PP), polycarbonate (PC), polyether ether ketone (PEEK), carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), aluminum oxide ceramic material and silicon nitride ceramic material with a density less than 2g / cm 3 .

[0074] The embodiment of the application obtains the optimal structure parameters of the static magnetic shielding box under the maximum shielding effectiveness by the above structure optimization method: the number of shielding layers n, the thickness t n of each shielding layer and the volume v n of the cubic structure formed by each shielding layer.

[0075] The structural optimization method provided in this invention can obtain the optimal structural parameters of the static magnetic shielding box more quickly and effectively, reducing errors while improving efficiency. Furthermore, the static magnetic shielding box manufactured based on these optimal structural parameters can significantly reduce the weight of the shielding layer and the risk of single-layer magnetic shielding saturation compared to existing technologies, thereby improving the stability of the magnetic environment and enabling wider application in fields such as electronics and medicine.

[0076] To better understand the technical solution provided by this invention, the following specific examples illustrate the structural optimization method of the static magnetic shielding box of this invention.

[0077] Example 1

[0078] This invention provides a method for optimizing the structure of a static magnetic shielding box, as detailed below:

[0079] (1) Construct a multi-layered static magnetic shielding box. From the inside out, the odd-numbered shielding layers are made of iron-based amorphous alloy with a relative permeability of 200,000. The even-numbered shielding layers are made of PMMA with a relative permeability of 1.

[0080] (2) The multi-layered magnetically shielded box and the multi-layered spherical shielded box are subjected to equal volume transformation, so that V n =v n The equivalent spherical radius of the nth shielding layer of the magnetically static shielding box is obtained. Among them, V n Let v be the volume of the nth layer of the multi-layer spherical shielded box. n Let n be the volume of the nth layer of the multi-layered magnetically shielded box.

[0081] (3) Based on the shielding effectiveness SE of the multi-layer spherical shielding box and the equivalent spherical radius r of the nth shielding layer n And the volume difference ΔV between the nth shielding layer and the (n-1)th shielding layer n Construct the objective function SE';

[0082] Specifically, the shielding effectiveness (SE) of the multi-layer spherical shielding box is: Where, μ n T represents the relative permeability of the nth shielding layer of a multi-layered spherical shielded box. n R is the thickness of the nth shielding layer of the multi-layer spherical shielding box. n Let ΔV be the inner radius of the nth shielding layer of the multi-layer spherical shielding box. n Let ΔV be the volume difference between the nth and (n-1)th shielding layers of the multi-layer spherical shielding box. n =V n -V n-1 =v n -v n-1 ;

[0083] The target function SE' is:

[0084]

[0085] (4) Establish the equivalence relationship between the thickness t2 of the second shielding layer of the static magnetic shielding box and the thickness T2 of the equivalent spherical shielding layer: the front view of the static magnetic shielding box provided by the application is shown in Figure 3 The innermost layer of the static magnetic shielding box is a cavity, d1 and d2 are the side lengths of the first and second cubic shielding layers, R1 and R2 are the radii of the first and second equivalent spheres, t2 and T2 are the thicknesses of the second cubic shielding layer and the second equivalent spherical shielding layer, respectively, and the following is obtained:

[0086] Then

[0087] Then The following can be obtained: The equivalence relationship between the thickness t2 of the second shielding layer of the static magnetic shielding box and the thickness T2 of the equivalent spherical shielding layer is obtained:

[0088] The following is introduced: Generalization is established to obtain the equivalence relationship between the thickness T of each shielding layer of the equivalent sphere and the thickness t of each shielding layer of the corresponding static magnetic shielding box: n n

[0089] The following is introduced: It is introduced into the target function SE' to uniformly map the structural parameters of the shielding layers of the static magnetic shielding box to the equivalent spherical model for static magnetic shielding box shielding effectiveness calculation:

[0090] Where μ n is the relative magnetic permeability of the nth shielding layer of the multi-layer static magnetic shielding box, π is the circular constant, t n is the thickness of the nth equivalent spherical shielding layer of the multi-layer static magnetic shielding box,

[0091] v n is the volume of the nth shielding layer of the multi-layer static magnetic shielding box.

[0092] (5) The number of shielding layers n of the static magnetic shielding box is set to be in the range [2, 10], and the particle swarm optimization algorithm is used to globally optimize the target function to search for the shielding layer number n with the maximum shielding effectiveness SE' and the thickness t n and volume parameters v​​n ; according to n, t n and v n Structural optimization is performed on the magnetostatic shielding box;

[0093] Wherein, when the particle swarm optimization algorithm is used, the number of particles N is 30 obtained by testing, the maximum iteration number iter corresponding to the layer number 50 is set max , according to the inertia weight formula Wherein, the maximum inertia weight w max is 0.9, the minimum inertia weight w min is 0.5, iter is the actual iteration number when converging, and the convergence accuracy threshold ∈ is 1e -3 , the search space boundary of t n is 0.5≤t n ≤1.

[0094] The result of the particle swarm optimization algorithm is that the shielding effectiveness of the magnetostatic shielding box reaches the highest when the total number of layers is 9.

[0095] Therefore, a magnetostatic shielding box with the innermost layer being a cubic cavity composed of 10 cubic nests and 9 shielding layers is constructed, the difference set between adjacent cubes constitutes a shielding layer, and the thickness of each shielding layer is determined by the optimal parameters optimized by the algorithm. From the inside out, the material of the odd shielding layer is iron-based amorphous alloy, the relative permeability of the odd shielding layer is 200000, the material of the even shielding layer is PMMA, and the relative permeability of the even shielding layer is 1.

[0096] (6) The shielding layer and the thickness and volume parameters of each layer of the magnetostatic shielding box when the shielding effectiveness is the largest are modeled and simulated using COMSOL Multiphysics software: set an ordinary uniform magnetic field with a strength of 0.5T, set the material of the cavity as air with a relative permeability of 1, for the 9 shielding layers from the inside to the outside, set the material of the odd layers as high permeability alloy with a relative permeability of 200000, and set the material of the even layers as plastic with a relative permeability of 1.

[0097] A one-dimensional plot set of magnetic flux density modes is obtained by simulation, and the shielding effectiveness is calculated using the magnetic flux density mode in the cavity of the shielding box and the magnetic flux density mode at the same position without shielding. The obtained shielding effectiveness is highly consistent with the algorithm optimization result, verifying the result of the algorithm optimization. In order to increase the reliability of the result, for the non-optimal layer number n, a fixed n value can be set to optimize the optimal parameters t n , v n under the fixed n, and COMSOL simulation verification is performed, and the predicted value of the final structural optimization method is compared with the actual value of COMSOL Multiphysics simulation, as Figure 4As shown in the figure, the green curve is the shielding effectiveness data of the static magnetic shielding box obtained by applying the method of the embodiment (referred to as algorithm optimization), and the blue curve is the simulation verification data of COMSOL (referred to as simulation verification). By comparing the two curves, it can be seen that the simulation results of the shielding effectiveness are basically consistent with the algorithm optimization results. Figure 4 It can be seen that the simulation results of the shielding effectiveness are basically consistent with the algorithm optimization results.

[0098] Those skilled in the art should further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized in electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been described in the above description in general terms. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0099] The steps of the method or algorithm described in combination with the embodiments disclosed herein can be implemented in hardware, software modules executed by a processor, or a combination of both. The software modules can be placed in random access memory (RAM), memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs or any other form of storage medium known in the art.

[0100] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for optimizing the structure of a static magnetic shielding box, characterized in that, The structural optimization method includes: A multi-layered magnetically shielded box is constructed. The magnetically shielded box has a cubic structure and includes a cavity and n shielding layers from the inside out, where n is an odd number greater than or equal to 3. From the inside out, the odd-numbered shielding layers are high relative permeability alloy layers, and the even-numbered shielding layers are low-density non-magnetic material layers. The n shielding layers are multiple concentrically arranged hollow cubic structures. Each shielding layer is subjected to an equal volume transformation to obtain the equivalent sphere radius (r) of the nth shielding layer. n ); An objective function is constructed based on the structural parameters of the shielding layer, wherein the objective function uses the thickness and volume of each shielding layer as variable parameters; the structural parameters of the shielding layer include: the thickness (t) of the nth shielding layer. n ), the volume of the nth shielding layer (v) n ), the equivalent sphere radius (r) of the nth shielding layer n The number of shielding layers (n) and the relative permeability (μ) of the material of the nth shielding layer. n ); An equivalence relationship is established between the thickness of each shielding layer of the static magnetic shielding box and the thickness of the corresponding equivalent spherical shielding layer. This equivalence relationship is then introduced into the objective function to uniformly map the structural parameters of the shielding layer to the equivalent spherical model for shielding effectiveness calculation. This allows the objective function to reflect the trend of shielding effectiveness variation under different thickness combinations. Based on the set constraints and parameter boundaries, the particle swarm optimization algorithm is used to globally optimize the objective function, search for the number of shielding layers with the highest shielding effectiveness and the thickness and volume parameters of each layer, and optimize the structure of the static magnetic shielding box based on the number of shielding layers with the highest shielding effectiveness and the thickness and volume parameters of each layer determined by the search results.

2. The structural optimization method for the static magnetic shielding box according to claim 1, characterized in that, The material of the high relative permeability alloy layer is at least one of the following: permalloy, superpermalloy, iron-silicon alloy, iron-cobalt alloy, iron-based amorphous alloy, and nanocrystalline alloy, with a relative permeability greater than or equal to 50,000. The low-density non-magnetic material layer is made of a material with a density of less than 2 g / cm³. 3 The material is selected from at least one of the following: polymethyl methacrylate (PMMA), polypropylene (PP), polycarbonate (PC), polyetheretherketone (PEEK), carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), alumina ceramic materials, and silicon nitride ceramic materials.

3. The structural optimization method for the static magnetic shielding box according to claim 1, characterized in that, The process involves performing an equal volume transformation on each shielding layer to obtain the equivalent sphere radius (r) of the nth shielding layer. n Specifically: By performing an equal-volume transformation between a multi-layered magnetically shielded box and a multi-layered spherical shielded box, V n =v n The equivalent spherical radius r of the nth shielding layer of the static magnetic shielding box is obtained. n : Where V n Let v be the volume of the nth layer of the multi-layer spherical shielded box. n Let n be the volume of the nth layer of the multi-layered magnetically shielded box.

4. The structural optimization method for the static magnetic shielding box according to claim 3, characterized in that, The construction of the objective function (SE') based on the structural parameters of the shielding layer specifically includes: Based on the shielding effectiveness SE of the multi-layer spherical shielding box and the equivalent spherical radius r of the nth shielding layer of the static magnetic shielding box. n And the volume difference ΔV between the nth shielding layer and the (n-1)th shielding layer n Construct the objective function SE'; where the shielding effectiveness SE of the multi-layer spherical shielding box is: μ n T represents the relative permeability of the nth shielding layer of a multi-layered spherical shielded box. n R is the thickness of the nth shielding layer of the multi-layer spherical shielding box. n Let ΔV be the inner radius of the nth shielding layer of the multi-layer spherical shielding box. n Let ΔV be the volume difference between the nth and (n-1)th shielding layers of the multi-layer spherical shielding box. n =V n -V n-1 =v n -v n-1 ; The objective function SE' is:

5. The structural optimization method for the static magnetic shielding box according to claim 4, characterized in that, The process of establishing an equivalence relationship between the thickness of each shielding layer in the static magnetic shielding box and the thickness of the corresponding equivalent spherical shielding layer, and incorporating this thickness equivalence relationship into the objective function, to uniformly map the structural parameters of the shielding layers to the equivalent spherical model for shielding effectiveness calculation, specifically includes: First, establish the equivalence relationship between the thickness t2 of the second shielding layer of the static magnetic shielding box and the thickness T2 of the equivalent spherical shielding layer: Will Generalization, establishing the thickness T of each shielding layer of the equivalent sphere. n The thickness t of each shielding layer in the corresponding static magnetic shielding box n The equivalence relation between them: Will The objective function SE' is introduced to uniformly map the structural parameters of the shielding layer of the magnetically static shielding box to an equivalent sphere model for calculating the shielding effectiveness of the magnetically static shielding box. Where, μ n The relative permeability of the nth shielding layer in a multi-layered magnetically shielded box is given by π, where π is pi and t is t. n The thickness of the nth equivalent spherical shielding layer of the multi-layered magnetically shielded box is given. v n Let n be the volume of the nth shielding layer of the multi-layered magnetically shielded box.

6. The structural optimization method for the static magnetic shielding box according to claim 1, characterized in that, Based on the set constraints and parameter boundaries, a particle swarm optimization algorithm is used to globally optimize the objective function, searching for the number of shielding layers with the highest shielding effectiveness and the thickness and volume parameters of each layer. Based on the results obtained from the search, the structure of the static magnetic shielding box is optimized, specifically including: The range of the number of shielding layers n in the static magnetic shielding box is defined. A particle swarm optimization algorithm is used to globally optimize the objective function, searching for the shielding layer number n and the thickness t of each layer that maximize the shielding effectiveness SE'. n and volume parameter v n According to n and t n and v n The structure of the static magnetic shielding box was optimized. When using the particle swarm optimization algorithm, the number of particles N is determined through testing, and the maximum number of iterations (iter) corresponding to the layer number n is set. max The inertia weight w is determined using a linear decreasing method, and the formula for the inertia weight w is: Among them, w max For the maximum inertia weight, w min The minimum inertia weight is given, iter is the actual number of iterations at convergence, and the convergence accuracy threshold is 1e. -3 Search t n The spatial boundary.

7. The structural optimization method for the static magnetic shielding box according to claim 1, characterized in that, The structural optimization method also includes simulation verification; the simulation verification includes: using the finite element method to model and simulate the number of shielding layers with the highest shielding effectiveness and the thickness and volume parameters of each layer.

8. The structural optimization method for the static magnetic shielding box according to claim 5, characterized in that, The finite element method includes: multiphysics simulation software (COMSOL Multiphysics).

9. A static magnetic shielding box, characterized in that, The static magnetic shielding box has a cubic structure, which includes a cavity and n shielding layers from the inside out, where n is an odd number greater than or equal to 3; the n shielding layers are arranged from the inside out, with odd-numbered layers being high relative permeability alloy layers and even-numbered layers being low-density non-magnetic material layers. The n-layer shielding layer is a plurality of concentrically arranged hollow cube structures; The structural parameters of the static magnetic shielding box are obtained by the structural optimization method described in any one of claims 1-8: the number of shielding layers n, the thickness t of each shielding layer. n The volume v of the cube formed by each shielding layer n .

10. The static magnetic shielding box according to claim 9, characterized in that, The material of the high relative permeability alloy layer is at least one of the following: permalloy, superpermalloy, iron-silicon alloy, iron-cobalt alloy, amorphous alloy, iron-aluminum alloy, and nanocrystalline alloy, with a relative permeability greater than or equal to 50,000. The low-density non-magnetic material layer is made of a material with a density of less than 2 g / cm³. 3 The material is selected from at least one of the following: polymethyl methacrylate (PMMA), polypropylene (PP), polycarbonate (PC), polyetheretherketone (PEEK), carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), alumina ceramic materials, and silicon nitride ceramic materials.

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