A bearing integrated with a magnetic shielding sandwich shell structure and a design and manufacturing method thereof

Abstract

A kind of bearing and magnetic shielding integrated sandwich shell structure and its design and manufacturing method, the structure mainly includes: inner skin, outer skin and the lattice core layer distributed between inner skin and outer skin, wherein the lattice core layer is closely distributed along the outer periphery and / or axial direction of inner skin, the gap between lattice units is minimized as much as possible, and the mechanical properties of the structure are strengthened.The BCC lattice cell with high stiffness is used in the lattice core layer of the structure to bear shear load, and the inner skin and outer skin bear in-plane force, so that the structure has good vibration reduction function, high resonance frequency and magnetic shielding performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of magnetic shielding and vibration technology, and particularly relates to a bearing and magnetic shielding integrated sandwich shell structure and a design and manufacturing method thereof. BACKGROUND

[0002] The service process of a spacecraft such as a satellite, a spaceship, a deep space probe, etc. generally involves the action of a constant magnetic field or magnetic field fluctuation generated by the earth, an extraterrestrial planet or a device of the spacecraft itself, which produces a non-negligible interference on the operation of sensitive devices (gyroscopes, atomic clocks, traveling wave tubes, angular displacement sensors, etc.) of the spacecraft for guidance, navigation and control, remote sensing imaging and scientific exploration, and brings severe challenges to frontier technologies and basic scientific researches such as high-precision control of the attitude of the spacecraft, high-precision positioning and navigation of the satellite, high-precision imaging on the earth and detection of space gravitational waves. For example, the magnetic field around a main detector photomultiplier tube of an effective load of a space hard X-ray imaging observation satellite is required to be less than 0.7 x 10 -4 T, the magnetic field noise of the environment in which an atomic spin gyroscope is located is required to be better than dozens of fT / Hz 1 / 2 , and the clock error prediction error of an atomic clock for autonomous switching of the working mode of a magnetic torque of the satellite attitude control can reach the level of attoseconds. The innovative design of a light-weight high-performance magnetic shielding structure becomes a key factor affecting the performance improvement of a magnetic sensitive platform device or an effective load function of a spacecraft in the fields of aerospace, etc.

[0003] The traditional magnetic shielding structure has the disadvantages of large density of solid materials, heavy structure mass, lack of rigidity and strength design against complex mechanical environment, etc., and has been unable to meet the stringent requirements of future aerospace equipment for the fusion of bearing and magnetic shielding functions and extreme light-weight performance. How to propose an innovative configuration and design strategy of a sandwich shell structure with bearing and magnetic shielding functions under the premise of meeting the light-weight requirement, establish the mechanical theory thereof, and reveal the performance coupling mechanism thereof has become a key technical problem and a key scientific problem to be solved in the field. SUMMARY

[0004] To solve the above technical problems, the present disclosure provides a bearing and magnetic shielding integrated sandwich shell structure and a design and manufacturing method thereof, to solve the problems of insufficient rigidity and strength of the magnetic shielding structure in the prior art, and difficulty in combining high strength and light weight.

[0005] The bearing and magnetic shielding integrated sandwich shell structure provided by the present disclosure is used for resisting constant magnetic field interference and vibration of sensitive devices, and mainly comprises an inner skin, an outer skin and a dot matrix core layer rigidly connected between the inner skin and the outer skin. In the structure, the inner cavity of the inner skin is used for placing sensitive devices; the dot matrix core layer is tightly distributed along the outer periphery and / or the axial direction of the inner skin, the gap between the dot matrix units is minimized as much as possible, and the structural mechanical properties are strengthened.

[0006] As preferred, the basic unit cell of the lattice core layer is a BCC lattice cell; the ends of the rods of adjacent cells are connected. The BCC lattice cell has excellent additive manufacturing performance, high magnetic shielding performance and high stiffness performance, for example, it has higher magnetic shielding performance and excellent additive manufacturing performance than a honeycomb core layer; it has higher structural stiffness and higher magnetic shielding performance than a pyramid cell.

[0007] As preferred, the inner skin, the outer skin and the lattice core layer are all made of high magnetic permeability material, for example, permalloy material.

[0008] As preferred, the inner skin and the outer skin are both cylindrical shell structures and have the same axis, and the lattice core layer is tightly distributed along the circumference and the axis of the cylinder.

[0009] Preferably, when the core layer region is distributed circumferentially, the ends of the rods between adjacent cells are connected.

[0010] Preferably, when the core layer region is distributed axially, the ends of the rods between adjacent cells are connected.

[0011] Preferably, the height h1 of the inner skin, the height h2 of the outer skin and the height h3 of the lattice core layer are equal.

[0012] The present disclosure provides a design method for the above structure, comprising the following steps:

[0013] Step 1) setting the initial values of the design parameters of the inner skin, the outer skin and the lattice core layer, which can specifically include:

[0014] Setting the structural material parameters of the inner skin, the outer skin and the lattice core layer, including relative magnetic permeability, density, elastic modulus and Poisson's ratio; the inner skin, the outer skin and the lattice core layer can be made of the same material;

[0015] Setting the inner diameters D1 and D2 and the wall thicknesses d1 and d2 of the inner skin and the outer skin, wherein the inner diameter is determined according to the required space size of the sensitive element placed in the cavity of the shell, and the wall thickness is set as an initial value, for example, d1 = d2 = d, and d is a pre-set thickness;

[0016] Setting the initial values of the edge length L of the lattice cell, the angle a between the horizontal diagonal and the edge, the angle β between the rod and the horizontal plane, and the rod radius r, wherein L = 0.05D, D is the diameter of the required space of the sensitive device, and r = D1 / 2,

[0017] The initial value of the number of the lattice core layer region lattice cells distributed circumferentially s and the number of the lattice core layer region lattice cells distributed axially n is set, wherein: if the lattice cells are uniformly distributed circumferentially along the core layer region, the number of the circumferentially distributed lattice cells in the preliminary design is s = 360 / [360 / (the circumference of the inner skin / L) + 1]; if the lattice cells are uniformly distributed axially in the core layer region, the number of the axially distributed lattice cells in the preliminary design is n = 30.

[0018] The height of the lattice core layer is set as h3 = n·L, the height of the inner skin is h1, the height of the outer skin is h2, and h1 = h2 = n·L.

[0019] Step 2), a finite element model of the lattice sandwich shell structure composed of the inner skin, the lattice core layer and the outer skin is established, including: a finite element model for magnetic shielding simulation and a finite element model for modal calculation. In the model, the inner cavity of the inner skin is used to place sensitive devices.

[0020] Further, the finite element model for magnetic shielding simulation selects solid elements, the finite element model for modal calculation selects a simplified model, the inner skin and the outer skin adopt shell elements, the lattice core layer adopts Euler beam elements, and the inner skin, the outer skin and the lattice core layer adopt rigid connection.

[0021] Step 3), according to the displacement constraint condition when the structure is used, a displacement boundary condition is applied, modal calculation is performed, and a natural frequency f1 is obtained;

[0022] Step 4), according to the on-orbit magnetic field working condition, a background static magnetic field is applied, the residual magnetic field intensity is calculated by using Maxwell equation, and the static magnetic shielding efficiency SE1 of the structure is obtained;

[0023] Step 5), the modal calculation result and the residual magnetic field intensity calculation result are compared with the first-order natural frequency constraint value f0 and the static magnetic shielding efficiency constraint value SE0 of the structure respectively, if f1 > f0 and SE1 > SE0, the structure design parameters meet the use requirement, and the configuration design scheme of the structure is completed; otherwise, steps j and k are performed.

[0024] j. If f1 ≥ f0 and SE1 < SE0, the thickness of the inner skin and the wall thickness of the outer skin are increased, d2 = 1.1d1, d3 = 1.1d2, and iteration is performed until f1 ≥ f0 and SE1 ≥ SE0 are met;

[0025] k. If f1 < f0 and SE1 ≥ SE0, the number of the axially distributed lattice cells is reduced, n2 = n1-1, n3 = n2-1, and iteration is performed until f1 ≥ f0 and SE1 ≥ SE0 are met. If n·L < h, the iteration is stopped, and step l is performed.

[0026] l.At this time, f1 < f0, and SE1 >= SE0, the number of lattice cells cannot meet the requirements, then increase the inner skin thickness and the outer skin wall thickness and the lattice rod radius at the same time, iterate according to d2 = 1.1d1, d3 = 1.1d2,..., and r2 = 1.1r1, r3 = 1.1r2,..., until f1 >= f0, and SE1 >= SE0 is met;

[0027] As preferred, in the above structure determination method, d = 0.5 mm.

[0028] In the present disclosure, a method for preparing the above sandwich shell structure by laser selective melting of metal powder is provided. Because high precision and high complexity can be achieved, lattice sandwich complex structures can be manufactured, and the process has the advantages of integrated additive manufacturing and easy post-processing, ensuring the overall stiffness and magnetic shielding performance of the structure.

[0029] The laser selective melting forming process parameter value range is laser power 280-290W, scanning speed 1050-1150mm / s, layer thickness 40μm, line spacing 0.12mm; after additive manufacturing, the structure is heated to 500±10℃ in the furnace, and after holding for 0.5±0.1 hours, it is quickly heated to 1050±10℃ and held for 4±0.1 hours, and then cooled to room temperature.

[0030] Through this set of processes, the physical properties of the additive manufactured permalloy can be improved, and the high magnetic permeability and excellent stiffness and strength performance of the material can be considered.

[0031] Through the structural design of the lattice sandwich cylindrical shell, the present disclosure realizes high stiffness in vibration and high anti-interference in static magnetism, and the first-order natural frequency and static magnetic shielding effectiveness meet the use requirements of most satellite payloads and static magnetic shielding.

[0032] Compared with the prior art, the present disclosure has the following beneficial effects: (1) by splitting the single-layer magnetic shielding cylindrical shell structure into an inner skin, an outer skin and a lightweight lattice core, wherein the weight of the lattice core is less than 30% of the weight of the original single-layer magnetic shielding cylindrical shell structure, the vibration high stiffness reaches 2-4 times the weight of the original structure;

[0033] (2) The first-order natural frequency of the traditional magnetic shielding structure is improved by more than twice, which can meet the requirements of the first-order natural frequency of the structure during the launch vehicle launch phase;

[0034] (3) The magnetic shielding effectiveness is greater than 46dB, which can meet the requirements that the sensitive devices are not affected by the magnetic field interference under the on-orbit magnetic field working condition of the spacecraft;

[0035] (4) The sandwich shell structure can meet the design requirements of the residual magnetic field strength and structural stiffness of sensitive devices such as spacecraft gyroscopes, atomic clocks, traveling wave tubes, and angular displacement sensors, and has good application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0036] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like parts throughout the figures, and wherein:

[0037] Figure 1 Fig. 1 is a schematic diagram of the inner skin and the outer skin according to an example embodiment of the present disclosure;

[0038] Figure 2 Fig. 2 is a schematic diagram of an example lattice cell;

[0039] Figure 3 Fig. 3 is a schematic diagram of the circumferential arrangement of an example lattice cell;

[0040] Figure 4 Fig. 4 is a schematic diagram of the axial arrangement of an example lattice cell;

[0041] Figure 5 Fig. 5 is a schematic diagram of the background magnetic field of an example sandwich shell structure according to the present disclosure;

[0042] Figure 6 Fig. 6 is a schematic diagram of the displacement constraint of an example sandwich shell structure according to the present disclosure;

[0043] Figure 7 Fig. 7 is a graph of the relationship between the first-order natural frequency and the number of axial lattice cells of the present disclosure;

[0044] Figure 8 Fig. 8 is a flowchart of an example method for determining a sandwich shell structure according to the present disclosure. DETAILED DESCRIPTION

[0045] Preferred embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. Although preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0046] The present disclosure aims at the problem of insufficient rigidity and strength of magnetic shielding structure in the prior art, and proposes a bearing and magnetic shielding integrated sandwich shell structure: by designing a lattice sandwich cylindrical shell structure, using high-rigidity BCC lattice cells to bear shear load, and the inner skin and the outer skin to bear in-plane force, so that the structure has good vibration reduction function, arranging the BCC lattice cells in the core layer region along the circumferential direction and the axial direction to improve the overall rigidity of the structure, so that the structure has high resonance frequency and magnetic shielding performance.

[0047] The following will be described in combination with the accompanying Figures 1 to 8 The bearing and magnetic shielding integrated sandwich shell structure determination method in an example embodiment is described.

[0048] First, the structure of the sandwich shell is described.

[0049] The sandwich shell structure in this embodiment is used for sensitive device static magnetic protection and bearing, which comprises an inner skin, an outer skin and a lattice core layer; the structure is prepared by laser selective melting forming process of metal powder, and due to the machining precision, the accuracy of the values of all the following dimensions is only 0.1mm; the inner skin and the outer skin are in the shape of cylindrical shell and have the same axis, as shown in the accompanying Figure 1 .

[0050] The space required by the sensitive device is set as a cylindrical region, the diameter is denoted as D, the height is denoted as h, the inner diameter, height and thickness of the inner skin are denoted as D1, h1 and d1 respectively, the inner diameter, height and thickness of the outer skin are denoted as D2, h2 and d2 respectively, wherein D1=D, D2=1.1D, d1=d2=d, h1=h2=n·L, it must be noted that due to the minimum size of additive manufacturing being 0.5mm, d>0.5mm, based on design rationality, the height of the inner skin and the outer skin should be equal to the height of the lattice core layer, i.e. h1, h2=h3, if it is convenient for manufacturing, it can also be rounded up.

[0051] As shown in the accompanying Figure 2 , the unit cell structure of the lattice core layer is a BCC lattice cell composed of 8 interconnected rods, the length, width and height of the cell are all L, in order to enable the lattice cell to connect the inner skin and the outer skin, L=0.05D, the radius of the rod is r, the value range of r cannot be too much smaller than the thickness of the skin, otherwise such structure cannot reach the corresponding rigidity, and it must be greater than the minimum size of additive manufacturing, it is preset that r=t1 / 2, the angle between the diagonal of the horizontal plane and the edge is a, the angle between the rod and the horizontal plane is b, and

[0052] As shown in the accompanying Figure 3As shown, the lattice cells are uniformly distributed along the circumference of the core layer. In order to make the structure more compact and continuously transmit the force, the ends of the cell rods are connected together as much as possible. The initial design of the number of circumferential lattice cells is s = 360 / [360 / [π·D1 / L]+1]. If the gap between the lattice cells is too large, s = [π·D1 / L]+1 can be made.

[0053] like Figure 4 As shown, the lattice cells are uniformly distributed along the axial direction. The initial design specifies that the number of axial lattice cells is n2 = 30, and the lattice core layer height is h3 = n·L.

[0054] like Figure 5 As shown, since the spacecraft orbits the Earth, the geomagnetic field interference is always radially parallel to the sandwich shell structure. Therefore, when calculating the static magnetic shielding effectiveness of the structure, a radial magnetic field is selected as the background static magnetic field, with the magnetic induction intensity being the same as the geomagnetic induction intensity of 5 × 10⁻⁶. -5 T;

[0055] like Figure 6 As shown, since the bottom of the structure is fixed by bolts during use, the displacement constraint is set as a fixed constraint at the bottom of the structure and a free constraint at the top of the structure during modal calculation.

[0056] To ensure reliable coupling between the inner skin, outer skin, and lattice core layer, the structure employs an integrated additive manufacturing method. The inner skin, outer skin, and lattice core layer are all made of the same material: permalloy, a high-permeability material.

[0057] This leads to an exemplary design method for a sandwich shell structure integrating load-bearing and magnetic shielding, as shown in the attached figure. Figure 8 As shown, the specific steps include:

[0058] a. The basic parameters of the sandwich shell structure material are denoted as: relative magnetic permeability is μ, density is ρ, elastic modulus is E, and Poisson's ratio is v;

[0059] b. Set the space required by the sensitive device as a cylindrical region, with the diameter denoted as D and the height as h. The inner diameters of the inner skin and the outer skin are denoted as D1 and D2, respectively, and D1 = D, D2 = 1.1D. The wall thicknesses of the inner skin and the outer skin are denoted as d1 and d2, respectively, and d1 = d2 = d, where d is a pre-set thickness.

[0060] c. The basic unit cell of the lattice core layer consists of 8 interconnected rods forming a BCC lattice cell. The cell side length is L, the rod radius is r, the angle between the horizontal face diagonal and the edge is α, and the angle between the rod and the horizontal plane is β. L = 0.1D, and r is assumed to be t1 / 2.

[0061] d. The dot matrix cells are uniformly distributed circumferentially along the core layer region, and the preliminary design circumferential dot matrix cell number s = 360 / [360 / [pi*D1 / L]+1]; and the dot matrix cells are uniformly distributed axially in the core layer region, and the preliminary design axial dot matrix cell number n = 25;

[0062] e. The dot matrix core layer height h3 = n*L, the inner skin height and the outer skin height are h1 and h2 respectively, and h1 = h2 = n*L;

[0063] f. A finite element model is established, including the dot matrix sandwich cylindrical shell structure composed of the inner skin, the dot matrix core layer and the outer skin, wherein the finite element model for magnetic shielding simulation selects solid elements, the finite element model for modal calculation selects a simplified model, the inner skin and the outer skin adopt shell elements, the dot matrix core layer adopts Euler beam elements, the inner skin, the outer skin and the dot matrix core layer adopt rigid connection mode, and the calculation efficiency is improved;

[0064] g. According to the displacement constraint condition when the structure is used, the displacement boundary condition is applied, the modal calculation is carried out, and a natural frequency f1 is obtained;

[0065] h. According to the on-orbit magnetic field working condition, the background static magnetic field is applied, the residual magnetic field strength is calculated by using Maxwell equation, and the static magnetic shielding efficiency SE1 of the structure is obtained;

[0066] i. The modal calculation result and the residual magnetic field strength calculation result are compared with the first-order natural frequency constraint value f0 and the structure static magnetic shielding efficiency constraint value SE0 respectively, if f1 > f0 and SE1 > SE0, the structure design parameters meet the use requirement, and the configuration design scheme of the sandwich shell structure is completed;

[0067] Otherwise, steps j, k or l are performed:

[0068] j. If f1 >= f0 and SE1 < SE0, increase the inner skin thickness and the outer skin wall thickness, and perform iteration according to d2 = 1.1d1, d3 = 1.1d2,..., until f1 >= f0 and SE1 >= SE0 are met;

[0069] k. If f1 < f0 and SE1 >= SE0, reduce the axial dot matrix cell number, and perform iteration according to n2 = n1-1, n3 = n2-1,..., until f1 >= f0 and SE1 >= SE0 are met, if n*L < h, stop iteration and go to step l;

[0070] l.At this time, f1 < f0, and SE1 ≥ SE0, the number of lattice cells cannot meet the requirements, then increase the inner skin thickness and the outer skin wall thickness and the lattice rod radius at the same time, d2 = 1.1d1, d3 = 1.1d2,..., and r2 = 1.1r1, r3 = 1.1r2,..., iteration until f1 ≥ f0, and SE1 ≥ SE0.

[0071] Application examples

[0072] A bearing and magnetic shielding integrated sandwich shell structure, which is a lattice sandwich cylindrical shell, comprises an inner skin, a lattice core layer and an outer skin, the entire lattice sandwich cylindrical shell is made of permalloy 1J80, and the material parameters of the permalloy 1J80 are as follows: relative magnetic permeability 40000, density 8400 kg / m 3 , elastic modulus 200 GPa, and Poisson's ratio 0.3.

[0073] A cylindrical space required by a sensitive device, with a diameter D = 70 mm and a height h = 150 mm.

[0074] The inner diameter D1 of the inner skin is D = 140 mm, the inner diameter D2 of the inner skin is 1.1D = 154 mm, the wall thicknesses of the inner skin and the outer skin are respectively denoted as d1 and d2, and d1 = d2 = d = 0.5 mm is preset.

[0075] The edge length L of the BCC lattice cell is 0.05D = 7 mm, the rod radius r is t1 / 2 = 0.25 mm, the angle between the horizontal diagonal line and the edge is α, and the angle between the rod and the horizontal plane is β.

[0076] The number of circumferential lattice cells s in the preliminary design is 360 / [360 / [π·D1 / L]+1] = 60, and the number of axial lattice cells n is 25.

[0077] The height h3 of the lattice core layer is n·L = 175 mm, the heights of the inner skin and the outer skin are respectively denoted as h1 and h2, and h1 = h2 = n·L = 175 mm.

[0078] The finite element models of the inner skin, the lattice core layer and the outer skin in the lattice sandwich cylindrical shell are established by using the Solidworks software, the Comsol software is used, a radial static magnetic field of 5×10 -5 T is applied, and the structural static magnetic shielding effectiveness SE1 = 47.3 dB is obtained.

[0079] The inner skin and the outer skin are simplified into shell units, and the lattice core layer is simplified into Euler beam units by using the Abaqus software, a fixed displacement constraint is applied to the bottom of the structure, modal calculation is performed, and the first-order natural frequency f1 = 1689 Hz of the structure is obtained.

[0080] The first order natural frequency and the static magnetic shielding effectiveness obtained by the finite element calculation are compared with the first order natural frequency constraint value f0 and the static magnetic shielding effectiveness constraint value SE0 respectively, and it is found that f1 = 1689Hz < f0 = 1800Hz, SE1 = 47.3dB > SE0 = 46dB, the first order natural frequency does not meet the use requirement, and step k is performed;

[0081] The number of axial lattice cells is reduced, n2 = n1-1, n3 = n2-1,..., iteration is performed, and the change of the first order natural frequency of the iteration structure is as shown in the formula (1) and the formula (2). Figure 7 As shown in the formula (1) and the formula (2), when n3 = 23, SE3 = 47.3dB > SE0 = 46dB, and f3 = 1822Hz > f0 = 1800Hz are met.

[0082] So far, the related parameters of the sandwich shell structure in the embodiment are determined.

[0083] Further, the inner skin, the lattice core layer and the outer skin are manufactured by additive manufacturing by using a laser selective melting forming technology, and a lattice sandwich cylindrical shell integrated structure is formed. Taking permalloy as an example, the laser selective melting forming manufacturing process parameter value range is: laser power 280-290W, scanning speed 1050-1150mm / s, layer thickness 40μm, line spacing 0.12mm; after additive manufacturing forming, the structure is heated to 500℃ in the furnace, and then rapidly heated to 1050℃ after 0.5 hours of heat preservation, and then cooled to room temperature after 4 hours of heat preservation.

[0084] Since the sandwich shell structure in the present disclosure has the internal open geometric characteristics, it can ensure that the unformed powder is easily removed in the post-processing stage, and has good process realizability.

[0085] The above technical solutions are only exemplary embodiments of the present application, and for those skilled in the art, on the basis of the application disclosed application method and principle, various types of improvements or modifications can be easily made, and are not limited to the method described in the above embodiment, therefore, the above described method is only preferred, and does not have the meaning of limitation.

Claims

1. A method of designing a load bearing and magnetic shielding integrated sandwich shell structure, the load bearing and magnetic shielding integrated sandwich shell structure comprising: An inner skin, an outer skin, and a lattice core layer between the inner and outer skins; wherein: The inner skin has an internal cavity for placing a sensitive device; The lattice core layer is closely distributed along the outer circumference and / or the axial direction of the inner skin; The inner skin, the outer skin, and the lattice core layer are made of high magnetic permeability material; The inner skin and the outer skin are cylindrical shell structures with the same axis; The inner skin, the outer skin, and the lattice core layer are made of permalloy material; The basic unit cell of the lattice core layer is a BCC lattice cell formed by a plurality of interconnected rods; the rod ends of adjacent cells are connected; The method comprises the following steps: S1, setting the initial values of the design parameters of the inner and outer skins and the lattice core layer; S2, establishing a finite element model of the lattice sandwich shell structure composed of the inner skin, the lattice core layer, and the outer skin, including: a finite element model for magnetic shielding simulation and a finite element model for modal calculation; S3, according to the displacement constraint condition when the structure is used, the displacement boundary condition is applied, the modal calculation is carried out, and the first-order natural frequency f1 is obtained; S4, according to the background static magnetic field under the on-orbit magnetic field working condition, the residual magnetic field intensity is calculated by using Maxwell equation, and the static magnetic shielding efficiency SE1 of the structure is obtained; S5, the modal calculation result and the residual magnetic field intensity calculation result are compared with the first-order natural frequency constraint value f0 and the structure static magnetic shielding efficiency constraint value SE0 respectively, if f1≥f0 and SE1≥SE0, the structure design parameters meet the use requirements, and the configuration design scheme of the structure is completed; Otherwise, the structure design parameters are adjusted gradually until f1≥f0 and SE1≥SE0.

2. The method of claim 1, wherein, The step S1 specifically comprises: Setting the structural material parameters of the inner and outer skins and the lattice core layer, including: relative magnetic permeability, density, elastic modulus, and Poisson's ratio; Setting the inner diameter and wall thickness of the inner and outer skins, wherein the inner diameter is determined according to the space size required by the sensitive device placed in the cavity of the shell, and the wall thickness is set as an initial value; The initial values of the edge length L of the lattice cell, the angle a between the horizontal diagonal and the edge, the angle β between the rod and the horizontal plane, and the radius r of the rod are set, wherein L = 0.05D, D is the diameter of the space required by the sensitive device, and r = inner skin wall thickness / 2, Setting the circumferential distribution number s and the initial value n of the axial distribution number of the lattice cell in the lattice core layer region, wherein: if the lattice cells are uniformly distributed along the circumference of the core layer region, the number of circumferential lattice cells is preliminarily designed as s=360 / [360 / (circumference of inner skin / L)+1]; if the lattice cells are uniformly distributed in the axial direction of the core layer region, the number of axial lattice cells is preliminarily designed as n=30; Setting the height of the lattice core layer, the height of the inner skin, and the height of the outer skin as n·L.

3. The method according to claim 1 or 2, characterized in that, The specific method of step S2 comprises: Establishing a finite element model of the lattice sandwich shell structure composed of the inner skin, the lattice core layer, and the outer skin, wherein the finite element model for magnetic shielding simulation selects solid elements, the finite element model for modal calculation selects a simplified model, the inner and outer skins adopt shell elements, the lattice core layer adopts Euler beam elements, and the inner and outer skins and the lattice core layer adopt rigid connection.

4. The method of claim 1, wherein, In step S5, the step of gradually adjusting the structure design parameters specifically comprises: S51, if f1≥f0 and SE1<SE0, iterative calculation is performed by gradually increasing the thickness of the inner skin and the wall thickness of the outer skin until f1≥f0 and SE1≥SE0 are met; S52, if f1 S53, through iterative calculation of gradually increasing the thickness of the inner skin, the thickness of the outer skin, and the radius of the lattice rod, until f1≥f0, and SE1≥SE0.

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