Design method of pressure-resistant and impact-resistant soft and hard dual-phase composite structure

Abstract

The invention discloses a design method of a pressure-resistant and impact-resistant soft and hard double-phase composite structure. The method comprises the following steps: determining geometric design parameters of a soft and hard double-phase composite unit cell structure; selecting a matched hard and soft phase matrix material, and determining material parameters; calculating an equivalent elastic modulus under the action of the impact load according to a cooperative deformation and energy dissipation mechanism; selecting a soft-hard double-phase composite multi-cell structure with multiple groups of geometric parameters to carry out finite element modeling calculation, simulating a load displacement relationship under a quasi-static compression test, and preselecting a group with the optimal bearing capacity; obtaining an equivalent stress strain relation according to the load displacement relation; the relationship between energy absorption and strain is obtained according to the equivalent stress-strain relationship, and the specific energy absorption of the soft and hard dual-phase composite unit cell structure is obtained through calculation; the effective elastic modulus and the specific energy absorption of the soft and hard double-phase composite unit cell structure are used as evaluation indexes, and geometric design parameters are adjusted to meet the design requirements of bearing and impact resistance. The soft and hard double-phase composite structure with the bearing capacity and the anti-impact capacity meeting the design requirements can be designed.

Description

Technical Field

[0001] This invention relates to the field of underwater pressure-resistant structure technology, and in particular to a design method for a soft and hard dual-phase composite structure. Background Technology

[0002] In fields such as deep-sea exploration, national defense, and security, extremely high requirements are placed on the pressure resistance and impact resistance of structural materials. Traditional single homogeneous materials (such as high-strength steel, titanium alloys, or ceramics) often face the contradiction of being "strong but not tough" or "tough but not strong": hard materials (such as ceramics) have high strength and hardness, and can effectively resist puncture and compression, but are prone to brittle fracture under impact; soft materials (such as polymers and rubber) have high toughness and energy dissipation capacity, but have limited pressure resistance and are easily deformed.

[0003] In existing technologies, the use of a soft-hard dual-phase composite structure is a mainstream solution. Traditional methods often draw inspiration from nature, such as the nacreous layer of seashells and biomimetic structures like bones. However, biomimetic design has certain limitations: firstly, natural structures are the result of long-term evolution, and their optimality is specific to certain biological loads, which may not match engineering loads; secondly, biomimetic structures are often complex in shape, difficult to manufacture, and costly.

[0004] Therefore, there is an urgent need for a new design method that can achieve the optimized layout and firm combination of soft and hard phases in three-dimensional space, thereby significantly improving the overall pressure resistance and impact resistance of composite structures. Summary of the Invention

[0005] The main objective of this invention is to provide a design method for a hard-soft dual-phase composite structure. Through theoretical and numerical simulation, a hard-soft dual-phase composite structure with load-bearing and impact resistance that meets design requirements can be designed and applied in the field of underwater explosion impact protection structure design.

[0006] The technical solution adopted in this invention is: A design method for a pressure-resistant and impact-resistant dual-phase composite structure, wherein the dual-phase composite structure comprises a hard phase matrix material and a soft phase matrix material coating the hard phase matrix material; comprising the following steps: S1. Determine the geometric design parameters of the soft-hard dual-phase composite unit cell structure. The soft-hard two-phase composite unit cell structure is hexahedral, and its hard phase matrix material includes rods located on the diagonals of the hexahedron; the geometric design parameters include the rod lengths. l ,radius r The unit cell side length L, and the angle θ between the rod and the horizontal plane; S2. Select matching hard phase matrix materials and soft phase matrix materials for configuration design and determine material parameters; S3. Based on the mechanism of coordinated deformation and energy dissipation of soft and hard dual-phase composite unit cell structure, establish a theoretical calculation formula for the equivalent elastic modulus of soft and hard dual-phase composite unit cell structure under impact load. S4. Select multiple sets of soft and hard two-phase composite multi-cell structures with different structural geometric parameters for finite element modeling and calculation, simulate the load-displacement relationship of the soft and hard two-phase composite multi-cell structures under quasi-static compression test, and pre-select the set with the best bearing capacity. S5. Obtain the equivalent stress-strain relationship based on the load-displacement relationship; S6. Based on the equivalent stress-strain relationship, the relationship between energy absorption and strain is obtained, and the specific energy absorption of the soft and hard dual-phase composite unit cell structure is further calculated. S7. Using the effective elastic modulus and specific energy absorption of the hard and soft dual-phase composite unit cell structure as evaluation indicators, adjust the geometric design parameters of the BCC unit cell structure to meet the load-bearing and impact-resistant design requirements.

[0007] In the above scheme, in step S2, the material parameters include the elastic modulus of the hard phase matrix material. E s Yield strength Poisson's ratio v y and density and the elastic modulus of soft phase matrix materials E r Yield strength Poisson's ratio v r and density .

[0008] In the above scheme, the theoretical calculation formula for the equivalent elastic modulus of the soft-hard two-phase composite unit cell structure established in step S3 is as follows:

[0009] In the formula, E The equivalent elastic modulus of the soft-hard dual-phase composite unit cell structure. E y The elastic modulus of a BCC unit cell structure composed of a hard phase matrix material. E r This represents the elastic modulus of the soft-phase matrix material. V f This represents the volume fraction of the hard phase matrix material.

[0010] In the above scheme, the elastic modulus of the BCC unit cell structure composed of hard phase matrix material is... E y The theoretical calculation formula is:

[0011] In the formula, It is an external load force; It is the equivalent length of the BCC unit cell structure; It is the deformation deflection of a unit cell beam; The correction factor representing the nodal volume effect. It is the effective length of the rod in a BCC unit cell structure; The correction factor representing the shear effect. G is the elastic modulus of the hard phase matrix material, and G is the shear modulus of the hard phase matrix material. k It is the shape factor of the beam cross section.

[0012] In the above scheme, in step S5, the formula for converting load displacement into equivalent stress and strain is:

[0013]

[0014] In the formula, The equivalent stress of the soft-hard dual-phase composite multicellular structure, It is the equivalent strain in the vertical direction of the soft-hard dual-phase composite multicellular structure. For compressive loads on a soft-hard dual-phase composite multicellular structure, ΔL The compression displacement is a two-phase composite multicellular structure with a soft and hard substrate.

[0015] In the above scheme, in step S6, the relationship between energy absorption and strain is obtained by performing the following integration based on the equivalent stress-strain relationship:

[0016] In the formula, This refers to energy absorption during the compression process of a soft-hard dual-phase composite multicellular structure.

[0017] In the above scheme, the specific energy absorption of the soft-hard dual-phase composite unit cell structure is calculated using the following formula:

[0018] In the formula, The specific energy absorption of the soft-hard dual-phase composite unit cell structure The quality of the soft-hard biphase composite multicellular structure.

[0019] In the above scheme, the hard phase matrix material is a metallic material, and the soft phase matrix material is a polymer material; the equivalent elastic modulus of the hard-soft dual-phase composite structure is greater than the elastic modulus of the hard phase matrix material.

[0020] This invention also proposes a pressure-resistant and impact-resistant soft-hard dual-phase composite structure, comprising a hard phase matrix material and a plurality of soft phase matrix materials filled inside the hard phase matrix material; the soft-hard dual-phase composite unit cell structure is hexahedral in shape, and its hard phase matrix material includes eight rods located on the diagonals of the hexahedron; the soft-hard dual-phase composite multi-cell structure is designed using the above-mentioned design method.

[0021] In the above scheme, the preparation method of the pressure-resistant and impact-resistant soft-hard dual-phase composite structure includes the following steps: (1) Preparation of hard phase matrix multicellular structure: using metal powder as raw material, hard phase matrix multicellular structure is printed using 3D laser selective melting forming equipment; (2) Soft phase matrix material infusion: The above-mentioned hard phase matrix multicellular structure is placed in the mold, and the liquid soft phase matrix material is slowly poured into the mold to reduce the generation of air bubbles; (3) Solidification of soft phase matrix material: After the mold is filled with soft phase matrix material, it is placed in a vacuum drying oven. The drying oven is heated to eliminate air bubbles and solidify the liquid soft phase matrix material. (4) Curing and demolding of soft and hard dual-phase composite multicellular structure: After the liquid soft phase matrix material is completely cured, the model is demolded to obtain the soft and hard dual-phase composite multicellular structure.

[0022] The beneficial effects of this invention are: The design method for pressure-resistant and impact-resistant dual-phase composite structures proposed in this invention can design dual-phase composite structures with load-bearing and impact resistance that meet design requirements. Through optimized design and interpenetration of the two phases in three-dimensional space, a "combination of rigidity and flexibility" effect is achieved. The hard phase ensures the structure's stiffness and strength to resist crushing, while the soft phase effectively absorbs impact energy and inhibits crack propagation. Its comprehensive pressure resistance and impact resistance performance far exceeds that of traditional composite structures. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a flowchart of the design method for the pressure-resistant and impact-resistant soft-hard dual-phase composite structure of the present invention; Figure 2 This is a schematic diagram of the soft and hard dual-phase composite structure in an embodiment of the present invention; Figure 3 This is a deformed diagram of a representative cell of the BCC single-cell structure in an embodiment of the present invention; Figure 4This is a numerical simulation diagram of the soft-hard dual-phase composite multicellular structure in an embodiment of the present invention; Figure 5 This is the compression deformation mode of the soft-hard dual-phase composite multicellular structure in the embodiments of the present invention; Figure 6 This is a load-displacement diagram of the hard phase matrix material with different rod diameters and lengths in an embodiment of the present invention; Figure 7 These are the equivalent stress-strain curves of the soft-hard dual-phase composite multicellular structure and the BCC multicellular structure of this invention; Figure 8 This is a flowchart illustrating the preparation process of the soft-hard biphase composite multicellular structure in this invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] It should be noted that the illustrations provided in the embodiments of the present invention are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0027] In this invention, it should also be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used only for descriptive and distinguishing purposes and should not be construed as indicating or implying relative importance.

[0028] like Figure 1 As shown, this invention proposes a design method for a pressure-resistant and impact-resistant soft-hard dual-phase composite structure, including the following steps: S1. Determine the geometric design parameters of the soft-hard dual-phase composite unit cell structure.

[0029] The hard-soft dual-phase composite structure comprises a hard phase matrix material and a soft phase matrix material coating the hard phase matrix material. The hard phase matrix material is made of metal, and the soft phase matrix material is made of polymer. The equivalent elastic modulus of the hard-soft dual-phase composite structure is greater than that of the hard phase matrix material. The overall unit cell structure of the hard-soft dual-phase composite structure is hexahedral, and its hard phase matrix material includes eight rods located on the diagonals of the hexahedron. Figure 2 The single-cell and multi-cell forms of the soft-hard dual-phase composite structure, as well as the single-cell and multi-cell forms of the BCC structure (i.e., the structure of the hard phase matrix material configuration), are shown respectively.

[0030] The geometric design parameters that need to be determined in this step include the length of the rod. l ,radius r The side length L of the unit cell, and the angle between the rod and the horizontal plane. θ In this embodiment, to simplify the design process, the overall soft-hard dual-phase composite unit cell structure is designed as a regular hexahedron. , The BCC multicell structure is obtained by arranging the BCC single-cell structure four times in the X, Y, and Z directions. The length of the BCC multicell structure is 4. L The BCC array multicell structure consists of 64 BCC single-cell structures.

[0031] S2. Select matching hard and soft matrix materials for configuration design and determine material parameters. Material parameters include the elastic modulus of the hard matrix material. E s Yield strength Poisson's ratio v y and density and the elastic modulus of soft phase matrix materials E r Yield strength Poisson's ratio v r and density .

[0032] The hard phase material in the hard-soft dual-phase composite unit cell structure can be selected from 316L stainless steel, 921A steel, aluminum alloy, and carbon fiber composite materials. This embodiment uses 316L stainless steel, a low-carbon "marine-grade" stainless steel whose core advantage lies in its excellent overall corrosion resistance. Due to the addition of molybdenum, it effectively resists pitting and crevice corrosion caused by chlorides. Simultaneously, its extremely low carbon content eliminates the tendency for intergranular corrosion after welding, ensuring the safety and stability of long-term post-weld use. Therefore, it is widely used in shipbuilding and marine engineering, coastal construction, and other fields. 316L stainless steel material parameters: elastic modulus... E sThe yield strength is 210 GPa. The material has a strength of 800 MPa and a Poisson's ratio. v y The density is 0.3. 7850kg / m 3 .

[0033] The soft phase material in the hard-soft dual-phase composite unit cell structure can be selected from epoxy resin, silicone, or shear-thickening gel. This embodiment uses epoxy resin, a thermosetting polymer with exceptionally high performance. Its core advantages lie in its superior adhesive strength, excellent mechanical strength, and strong chemical resistance. It can form strong bonds with various materials such as metals, ceramics, and glass, far exceeding its own strength; after curing, it has high hardness, wear resistance, and dimensional stability; and it also has excellent resistance to acids, alkalis, solvents, and other chemicals. Furthermore, it possesses excellent electrical insulation, low curing shrinkage, and flexible moldability, making it an irreplaceable key material in the field of composite materials. Epoxy resin (ER) material parameters: Elastic modulus E r The yield strength is 3 GPa. The strength is 235 MPa, and the material's Poisson's ratio is... v r The density is 0.38. 1200 kg / m 3 .

[0034] S3. Based on the mechanism of coordinated deformation and energy dissipation of soft and hard two-phase composite unit cell structures, a theoretical calculation formula for the equivalent elastic modulus of soft and hard two-phase composite unit cell structures under impact load is established.

[0035] For BCC unit cell structures, such as Figure 3 As shown, the effective performance of the BCC unit cell structure is calculated using Timoshenko beam theory and considering shear effects. The deformation deflection of the unit cell beam is determined through geometric relationships. and strain The relationship can be defined as follows: (1) in, h This represents the vertical displacement of the cell. It is the deformation deflection of a unit cell beam.

[0036] According to Timoshenko-Liang theory, we have: (2) in, F It is the shear force acting on the beam. Indicates the angle of twist of the beam. I It is the moment of inertia of the beam's cross section.x This indicates the horizontal displacement along the length of the beam.

[0037] Solve for the first differential of equation (2) and apply the boundary conditions. ,get: (3) Under the action of external force, the deflection gradient of the beam is: (4) in k =1.1 is the shape factor of the beam section, G is the material shear modulus, and A is the cross-sectional area of ​​the beam. It is the deformation deflection of the unit cell beam. Substituting the beam rotation equation (3) into equation (4), and according to the boundary conditions... Solve the first-order differential equation: (5) The final deflection of the beam is at the free end, therefore: (6) Substituting equations (1) and (6) into the constitutive governing equations of the BCC unit cell structure, we get: (7) Among them, E y The elastic modulus of the BCC unit cell structure; It is unit cell compressive stress. and A These are the external load force and the corresponding area of ​​action, respectively. It is the equivalent length of the BCC unit cell structure; The correction factor representing the nodal volume effect. It is the effective length of the rod in a BCC unit cell structure; Correction factor representing the shear effect .

[0038] The behavior of composite structures can be simplified to a weighted average of the volume fractions of their components. For two-phase structures (solid framework and filled resin), the most commonly used simple model is the Voigt upper bound model.

[0039] The model assumes that the two phases of material are subjected to the same strain.

[0040] Formula for calculating equivalent elastic modulus: (8) In the formula, E The equivalent elastic modulus of the soft-hard dual-phase composite unit cell structure. E yThe elastic modulus of the BCC unit cell structure. E r This represents the elastic modulus of the soft-phase matrix material. V f This represents the volume fraction of the hard phase matrix material.

[0041] S4. Select multiple sets of soft and hard two-phase composite multicellular structures with different structural geometric parameters for finite element modeling and calculation, such as... Figure 4 As shown, the load-displacement relationship of a soft-hard two-phase composite multicellular structure under a simulated quasi-static compression test is illustrated. By comparing the differences in load-displacement relationships under different material types and structural geometric parameters, a set of soft-hard two-phase composite multicellular structures with optimal compressive strength is pre-selected. During compression, the deformation modes of the soft-hard two-phase composite multicellular structure are as follows: Figure 5 As shown.

[0042] In this embodiment, the finite element modeling process includes component creation, assigning material properties, assembling components, setting interactions, mesh generation, and setting boundary conditions. The interaction is set to general contact, the friction factor is set to 0.15, the mesh size is 0.15 mm, and the loading boundary condition is set to a uniform loading rate of 4 mm / min applied to the upper end while the lower end is fixed. This process calculates the load-displacement relationship of the soft-hard two-phase composite multicellular structure under a quasi-static compression test, comparing the differences in load-displacement relationships under the parameters of side length L = 4 mm, 5 mm, and 6 mm for the hard phase matrix material, and radius r = 0.2 mm, 0.25 mm, and 0.3 mm for the hard phase matrix material. The results are as follows: Figure 6 As shown, under the same displacement conditions, the hard phase matrix material with a side length L=4mm and a radius r=0.3mm has a higher load, that is, a higher load-bearing capacity.

[0043] S5. For the soft-hard two-phase composite multicellular structure pre-selected in S4, the equivalent stress-strain relationship of the soft-hard two-phase composite multicellular structure is obtained by using the quasi-static compression load-displacement curve of the soft-hard two-phase composite multicellular structure obtained from numerical simulation through the following nominal stress and strain transformation calculation method: (9) (10) In the formula, The equivalent stress of the soft-hard dual-phase composite multicellular structure, It is the equivalent strain in the vertical direction of the soft-hard dual-phase composite multicellular structure. For compressive loads on a soft-hard dual-phase composite multicellular structure, ΔL The compression displacement is a two-phase composite multicellular structure with a soft and hard substrate.

[0044] Figure 7The equivalent stress-strain curves of the soft-hard dual-phase composite multicellular structure and the BCC multicellular structure are shown. By comparison, it can be seen that the soft-hard dual-phase composite multicellular structure has a higher equivalent stress under the same equivalent strain conditions than the BCC multicellular structure, indicating that the soft phase matrix material encapsulating the hard phase matrix material has a higher load-bearing capacity than the single hard phase matrix material.

[0045] S6. Based on the equivalent stress-strain relationship of the soft-hard dual-phase composite multi-cell structure, the relationship between energy absorption and strain is obtained, which is used to evaluate the impact resistance of the structure, and the specific energy absorption of the soft-hard dual-phase composite single-cell structure is further calculated.

[0046] Based on the equivalent stress-strain relationship, the following integration yields the relationship between energy absorption and strain:

[0047] In the formula, This refers to energy absorption during the compression process of a soft-hard dual-phase composite multicellular structure.

[0048] The specific energy absorption of the soft-hard dual-phase composite unit cell structure is calculated using the following formula:

[0049] In the formula, The specific energy absorption of the soft-hard dual-phase composite unit cell structure The quality of the soft-hard biphase composite multicellular structure.

[0050] S7. Using the effective elastic modulus and specific energy absorption of the hard and soft dual-phase composite unit cell structure as evaluation indicators, adjust the geometric design parameters of the BCC unit cell structure to meet the load-bearing and impact-resistant design requirements.

[0051] In this embodiment, the method for adjusting the geometric design parameters of the hard-soft two-phase composite unit cell structure is as follows: among the structural geometric design parameters (r, l), select any one geometric parameter, fix the other parameters, and calculate the effective elastic modulus and specific energy absorption of the hard-soft two-phase composite unit cell structure using finite element method within the range of its variable values. Compare the calculation results with the evaluation indicators. When all evaluation indicators are met, the calculation is stopped, indicating that the set of structural parameters meets the load-bearing and impact-resistant design requirements of the hard-soft two-phase composite structure. If not, the geometric design parameters need to be changed, and the iterative calculation continues until all evaluation indicators are met.

[0052] Finally, based on the optimal structural design parameters selected through theoretical and numerical simulation optimization, a hard-soft dual-phase composite multicellular structure was prepared through a process involving the fabrication of a hard-phase matrix multicellular structure, the infusion of a soft-phase matrix material, the solidification of the soft-phase matrix material, and the curing and demolding of the hard-soft dual-phase composite multicellular structure. (See [link to relevant documentation]). Figure 8 The specific preparation process is as follows: (1) Preparation of hard phase matrix multicellular structure: Using 316L stainless steel powder as raw material, a small SLM metal 3D printing device, DiMetal-100H, specifically developed for forming small-sized parts, was used to print hard phase matrix multicellular structures. The laser forming process parameters of the metal 3D printing device were as follows: laser power 250W, scanning speed 950mm / s, layer thickness 0.04mm, and scanning spacing 0.1mm. The entire laser scanning process was carried out in a forming chamber filled with argon gas to avoid oxidation.

[0053] (2) Soft phase matrix material pouring: First, using an electronic balance with an accuracy of 0.01g, accurately weigh the epoxy resin and matching curing agent at a weight ratio of 3:1. Pour both into a clean container and stir at a constant speed for 2-3 minutes using a glass rod or mechanical stirrer until the mixture is uniform and transparent, without visible streaks or undispersed components. To reduce the introduction of air bubbles, stir slowly along the container wall and avoid vigorous stirring. Then, slowly and continuously pour the mixed epoxy resin into the mold cavity. The pouring process should maintain a single pouring path, and the pouring port should be as close as possible to the bottom of the mold to reduce turbulence and gas entrainment.

[0054] (3) Solidification of the soft phase matrix material: During the solidification process of epoxy resin, internal defects, especially the generation and elimination of bubbles, must be strictly controlled. After the epoxy resin is poured, the mold is smoothly moved into the vacuum drying oven. By evacuating the oven, the pressure inside is gradually reduced, which helps the dissolved gases and tiny bubbles inside the material to escape. At the same time, the heating program is started to reduce the viscosity of the epoxy resin and enhance its fluidity, further promoting the rise and elimination of bubbles. This process is usually maintained at a certain temperature and vacuum for a period of time to ensure that the epoxy resin is fully cured, the internal structure is dense and uniform, and finally a bubble-free, stable soft-hard two-phase composite multicellular structure is formed.

[0055] (4) Curing and Demolding of Soft-Hard Dual-Phase Composite Multicellular Structure: After the epoxy resin has fully cured under the set temperature and time conditions to form a stable solid structure, the demolding operation can be carried out. Care must be taken during demolding to avoid damaging the soft phase area or the hard phase portion bonded to it. Because the mold is printed using water-soluble materials, and the epoxy resin used in this invention is insoluble in water, demolding can be completed simply by placing the mold in water.

[0056] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0057] The order of the steps in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0058] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A design method of a pressure-resistant impact-resistant soft-hard dual phase composite structure, the soft-hard dual phase composite structure including a hard phase matrix material and a soft phase matrix material coating the hard phase matrix material; characterized in that, Design methods include: S1. Determine the geometric design parameters of the soft-hard dual-phase composite unit cell structure. The soft-hard dual-phase composite unit cell structure is a hexahedron, the BCC unit cell structure of which comprises a rod located on a diagonal line of the hexahedron; the geometric design parameters comprise a rod length of the rod l , a radius r , a unit cell edge length L, and an included angle θ of the rod and a horizontal plane; S2. Select matching hard phase matrix materials and soft phase matrix materials for configuration design and determine material parameters; S3. Based on the mechanism of coordinated deformation and energy dissipation of soft and hard two-phase composite unit cell structure, establish the theoretical calculation formula for the equivalent elastic modulus under impact load. S4. Select multiple sets of soft and hard two-phase composite multi-cell structures with different structural geometric parameters for finite element modeling and calculation, simulate the load-displacement relationship under quasi-static compression test, and pre-select the set with the best bearing capacity. S5. Obtain the equivalent stress-strain relationship based on the load-displacement relationship; S6. Based on the equivalent stress-strain relationship, the relationship between energy absorption and strain is obtained, and the specific energy absorption of the soft and hard two-phase composite unit cell structure is calculated. S7. Using the effective elastic modulus and specific energy absorption of the hard and soft dual-phase composite unit cell structure as evaluation indicators, adjust the geometric design parameters of the BCC unit cell structure to meet the load-bearing and impact-resistant design requirements.

2. The design method of the pressure-resistant and impact-resistant soft-hard dual-phase composite structure according to claim 1, characterized in that, In step S2, the material parameters include the elastic modulus of the hard phase matrix material E s , the yield strength , the Poisson's ratio v y and the density , and the elastic modulus of the soft phase matrix material E r , the yield strength , the Poisson's ratio v r and the density .

3. The design method of pressure-resistant impact-resistant soft-hard dual phase composite structure according to claim 1, characterized in that, In step S3, the theoretical formula for calculating the equivalent elastic modulus of the soft-hard two-phase composite unit cell structure is as follows: wherein, E Eeff is the equivalent elastic modulus of the soft-hard dual-phase composite unit cell structure, E y Ebcc is the elastic modulus of the BCC unit cell structure composed of the hard phase matrix material, E r Esoft is the elastic modulus of the soft phase matrix material, V f Vh is the volume fraction of the hard phase matrix material.

4. The design method of the pressure-resistant and impact-resistant soft-hard dual-phase composite structure according to claim 3, characterized in that, Elastic modulus of BCC unit cell structure of hard phase matrix material E y The theoretical calculation formula is: wherein is the external load force; is the equivalent length of the BCC unit cell structure; is the deformation deflection of the unit cell beam; is a correction factor representing the nodal volume effect, is the effective length of the rod of the BCC unit cell structure; is a correction factor representing the shear effect, is the elastic modulus of the hard phase matrix material, G is the shear modulus of the hard phase matrix material, k is the shape factor of the beam cross section.

5. The design method of the pressure-resistant and impact-resistant soft-hard dual-phase composite structure according to claim 1, characterized in that, In step S5, the formula for converting load displacement into equivalent stress and strain is: In the formula, The equivalent stress of the soft-hard dual-phase composite multicellular structure, It is the equivalent strain in the vertical direction of the soft-hard dual-phase composite multicellular structure. For compressive loads on a soft-hard dual-phase composite multicellular structure, ΔL The compression displacement is a two-phase composite multicellular structure with a soft and hard substrate.

6. The design method of the pressure-resistant and impact-resistant soft-hard dual-phase composite structure according to claim 5, characterized in that, In step S6, the relationship between energy absorption and strain is obtained by performing the following integration based on the equivalent stress-strain relationship: In the formula, This refers to energy absorption during the compression process of a soft-hard dual-phase composite multicellular structure.

7. The design method of the pressure-resistant and impact-resistant soft-hard dual-phase composite structure according to claim 6, characterized in that, The specific energy absorption of the soft-hard dual-phase composite unit cell structure is calculated using the following formula: In the formula, The specific energy absorption of the soft-hard dual-phase composite unit cell structure The quality of the soft-hard biphase composite multicellular structure.

8. The design method of the pressure-resistant and impact-resistant soft-hard dual-phase composite structure according to claim 1, characterized in that, The hard phase matrix material is made of metal, and the soft phase matrix material is made of polymer; the equivalent elastic modulus of the hard-soft dual-phase composite structure is greater than that of the hard phase matrix material.

9. A pressure-resistant and impact-resistant dual-phase composite structure, comprising a hard phase matrix material and a plurality of soft phase matrix materials filled within the hard phase matrix material; characterized in that, The soft-hard dual-phase composite unit cell structure is a hexahedron, and its hard phase matrix material includes eight rods located on the diagonals of the hexahedron; the soft-hard dual-phase composite multi-cell structure is designed using the design method described in any one of claims 1-8.

10. The pressure-resistant and impact-resistant dual-phase composite structure according to claim 9, characterized in that, The preparation method of the pressure-resistant and impact-resistant soft-hard dual-phase composite structure includes the following steps: (1) Preparation of hard phase matrix multicellular structure: using metal powder as raw material, hard phase matrix multicellular structure is printed using 3D laser selective melting forming equipment; (2) Soft phase matrix material infusion: The above-mentioned hard phase matrix multicellular structure is placed in the mold, and the liquid soft phase matrix material is slowly poured into the mold to reduce the generation of air bubbles; (3) Solidification of soft phase matrix material: After the mold is filled with soft phase matrix material, it is placed in a vacuum drying oven. The drying oven is heated to eliminate air bubbles and solidify the liquid soft phase matrix material. (4) Curing and demolding of soft and hard dual-phase composite multicellular structure: After the liquid soft phase matrix material is completely cured, the model is demolded to obtain the soft and hard dual-phase composite multicellular structure.

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