Lightweight shock-resistant composite material and method for manufacturing same

Abstract

The application belongs to the technical field of advanced composite materials and structure engineering, and particularly relates to a lightweight anti-seismic composite material and a preparation method thereof. The material is a sandwich structure, comprising upper and lower panels and an intermediate core layer. The upper and lower panels are composed of a resin matrix and carbon fibers in which metal nanoparticles are in-situ compounded. The intermediate core layer is prepared by laser selective melting or precise sheet metal folding to obtain a negative Poisson's ratio metal lattice core layer and then subjected to surface roughening treatment. A core-shell damping emulsion is prepared on the surface of the core layer by a step-by-step emulsion polymerization method, and a functional damping coating is formed by coating and solidification. The panels and the core layer are compounded and solidified by a vacuum-assisted resin transfer molding process. Through multi-scale collaborative design, the lightweight, high strength, high damping and excellent impact resistance are synergistically optimized, the structure has high integrity and high designability, and is suitable for building seismic mitigation, lightweight transportation and high-end equipment protection.

Description

Technical Field

[0001] This application belongs to the field of advanced composite materials and structural engineering technology, and specifically relates to a lightweight earthquake-resistant composite material and its preparation method. Background Technology

[0002] In the fields of construction, transportation, and equipment manufacturing, the requirements for structural materials are increasingly trending towards a combination of lightweight, high strength, and high energy efficiency. Traditional seismic-resistant materials such as steel and concrete have significant self-weight and typically limited damping performance, making it difficult to meet the dual demands of efficiency and safety in modern engineering. Currently, some technologies attempt to improve material properties through single methods, such as using lightweight sandwich structures to increase specific strength or utilizing damping materials to enhance vibration reduction. However, these methods often have shortcomings in overall performance: the damping performance of lightweight sandwich structures is often insufficient, while adding damping materials may increase weight or weaken overall strength. Furthermore, in fiber-reinforced composite materials, the interfacial bond strength between the fiber and the matrix is ​​crucial to performance, but traditional methods for strengthening this interface have limited effectiveness and are complex processes.

[0003] To overcome this predicament, the industry has explored several technologies: some solutions employ honeycomb sandwich structures (such as the nano-modified vibration damping honeycomb sandwich panel disclosed in patent CN106313761A), which improves damping performance by adding nano-modified powder to the carbon fiber panel. However, the core layer is still a traditional positive Poisson's ratio honeycomb structure, resulting in limited energy absorption efficiency. Furthermore, the nanoparticles are only dispersed in the resin matrix, failing to effectively solve the interfacial bonding problem between the fiber and the matrix. Other technologies attempt to coat the surface of the lattice metal core with a damping coating (such as the lattice metal-acrylic resin-based damping coating composite structure in patent CN106915104A). Its core layer is a positive Poisson's ratio configuration such as a pyramid or corrugation. The lateral shrinkage deformation characteristics during impact result in insufficient energy dissipation, and the panel lacks interfacial reinforcement design, limiting the overall load-bearing capacity.

[0004] The emergence of negative Poisson's ratio metamaterials has provided a new path for improving impact resistance. Existing technologies have developed negative Poisson's ratio structures based on metal rubber, concave hexagonal cells, etc., which significantly improve energy absorption capacity by utilizing the lateral expansion characteristics under pressure. However, these structures are mostly single-core designs, lacking synergistic integration with high-damping coatings and reinforced panels, resulting in insufficient damping performance or weak interfacial bonding. Although patent KR1020220035502 discloses a multi-layer composite structure containing negative Poisson's ratio fibers, it adopts a multi-segment heterogeneous fiber winding process, which is complex and costly. Moreover, the damping performance depends on the frictional damping of the core layer itself, resulting in limited vibration reduction effect.

[0005] Furthermore, the interfacial bonding strength problem prevalent in fiber-reinforced composites remains unresolved. Traditional solutions either employ surface coating with nanoparticles or rely on adhesive bonding, but the former is prone to particle detachment, while the latter has limited bonding strength, making it difficult to achieve efficient stress transfer and hindering the overall mechanical properties of the material. Simultaneously, existing composite processes often focus on optimizing a single structure or property, lacking a systematic integration of the multi-scale synergistic mechanism of negative Poisson's ratio structure, interfacial reinforcement, and damping coating. This makes it difficult for materials to simultaneously meet the integrated requirements of lightweight, high strength, high damping, and high impact resistance. Summary of the Invention

[0006] To address the aforementioned problems, in a first aspect, this application proposes a lightweight, earthquake-resistant composite material, which is a sandwich structure, comprising: Both the upper and lower panels are made of resin matrix and reinforcing material through impregnation; the reinforcing material is carbon fiber with in-situ composite metal nanoparticles. The intermediate core layer is a metal lattice structure with zero Poisson ratio or negative Poisson bit characteristics, which is disposed between the upper panel and the lower panel; the surface of the metal lattice structure is coated with a functional damping coating.

[0007] Furthermore, the metal nanoparticles are copper, zinc, silver, or nickel nanoparticles with a particle size of 5-50 nm. The metal lattice structure is made of aluminum alloy, titanium alloy or magnesium alloy, with a volume relative density of 10-20%, based on the corresponding dense metal.

[0008] Furthermore, the functional damping coating is a nano-core-shell structure formed by epoxy resin / acrylate, and the coating thickness is 50-200μm; The core layer of the nano-core-shell structure is an acrylate elastomer, and the shell layer is an epoxy resin, with a mass ratio of core layer to shell layer of 3:1-5:1.

[0009] Furthermore, the cell configuration of the metal lattice structure includes concave hexagons, double-arrow shapes, triangles, chiral structures, or functional gradient structures designed through topology optimization. The Poisson's ratio of the functionally graded structure designed through topology optimization gradually changes from -0.1 to -0.3 in the core of the metal lattice structure to 0 to 0.1 towards the edge of the structure.

[0010] Furthermore, the resin matrix is ​​epoxy resin; Alternatively, the resin matrix may be an epoxy resin with added chemical foaming agent, wherein the amount of chemical foaming agent added accounts for 0.5-2% of the total amount of epoxy resin; The chemical foaming agent is azodicarbonamide or sodium bicarbonate.

[0011] Secondly, this application proposes a method for preparing a lightweight earthquake-resistant composite material, comprising the following steps: Preparation of carbon fibers in situ composited with metal nanoparticles: a spinning solution containing a metal source and a carbon fiber precursor is electrospinned to form a precursor fiber membrane. The precursor fiber membrane is then subjected to pre-oxidation treatment and high-temperature calcination treatment under an inert atmosphere to obtain carbon fibers in situ composited with metal nanoparticles. Fabrication of a negative Poisson's ratio metal lattice core layer: Based on a pre-defined three-dimensional model, a metal lattice structure with zero or negative Poisson's ratio characteristics is fabricated, and its surface is roughened. Applying a functional damping coating: applying damping material to the roughened surface of the metal lattice structure, and curing it to form a functional damping coating. Composite curing molding: The carbon fiber in situ composited with metal nanoparticles is used as the panel, and a metal lattice structure with a functional damping coating cured on the surface is placed between the upper panel and the lower panel as the core layer. A resin matrix is ​​introduced, and the composite material is obtained by vacuum-assisted impregnation and molding curing.

[0012] Furthermore, in the process of preparing metal nanoparticle-doped carbon fiber preforms, The metal source is zinc nitrate, copper acetate, silver nitrate, or nickel nitrate; The carbon fiber precursor is polyacrylonitrile; The metal source in the spinning solution has a mass fraction of 5-15%, and the polyacrylonitrile mass fraction has a mass fraction of 8-12%. The pre-oxidation treatment conditions are 220-280℃ for 1.5-2.5 hours; The conditions for the high-temperature calcination treatment are calcination at 800-1200℃ for 1.5-2.5 hours.

[0013] Furthermore, in the process of preparing the negative Poisson's ratio metal lattice core layer, the roughening treatment is sandblasting or chemical etching, and the surface roughness Ra of the metal lattice structure after treatment is 1.5-3.0 μm.

[0014] Furthermore, during the application of the functional damping coating, the damping material is prepared via a stepwise emulsion polymerization method, specifically: Using acrylate monomers as the core layer raw material, an emulsion is formed under the action of an emulsifier, and then epoxy resin monomers are added for shell layer polymerization to obtain an epoxy resin / acrylate core-shell emulsion. An epoxy resin / acrylate core-shell emulsion is uniformly coated onto the surface of a metal lattice core layer by spraying, and a functional damping coating is obtained after curing at 80-120℃ for 0.5-2 hours. The acrylate monomers include one or more combinations of butyl acrylate, methyl methacrylate, and isooctyl acrylate.

[0015] Furthermore, during the composite curing and molding process, The vacuum-assisted impregnation process employs a vacuum-assisted resin transfer molding process with a vacuum degree of -0.09 to -0.07 MPa. The molding curing conditions are: temperature 100-140℃, pressure 0.5-1.0MPa, and time 2-4 hours.

[0016] Compared with the prior art, this application has the following advantages: This application employs a sandwich structure consisting of an in-situ reinforced carbon fiber panel with metal nanoparticles, a negative Poisson's ratio metal lattice core layer, and a nano-core-shell damping coating, achieving synergistic improvements in multiple performance aspects. The unique deformation mechanism of the negative Poisson's ratio core layer, which expands laterally under pressure, increases impact energy absorption efficiency by more than 40% compared to traditional positive Poisson's ratio honeycomb structures. The nano-core-shell damping coating efficiently converts vibration energy into heat energy, with a damping loss factor more than double that of pure resin coatings. The in-situ generated metal nanoparticles form micro-anchors between the carbon fiber and resin, increasing interlayer shear strength by more than 20% compared to unmodified carbon fiber panels, ultimately achieving lightweight construction (area density as low as 5.2 kg / m³). 2 It integrates high strength (three-point bending strength up to 312MPa), high damping (damping loss factor 0.085) and high impact resistance (drop hammer impact energy absorption 45.6 J / g).

[0017] Compared to traditional physical mixing of nanoparticles for interface strengthening, this application utilizes electrospinning and in-situ reduction processes to firmly embed metal nanoparticles (copper, zinc, silver, nickel, etc.) within carbon fibers, forming a stable fiber-nanoparticle-resin interface structure. This effectively avoids particle detachment or interface delamination, significantly improving stress transfer efficiency and structural load-bearing stability. Tests show that the interlaminar shear strength of this application reaches 28.7 MPa, far exceeding the performance levels of non-in-situ doping schemes and commercial carbon fiber panels.

[0018] The functional damping coating of this application adopts an epoxy resin / acrylate nano core-shell structure. The elastomeric properties of the core layer and the rigid structure of the shell layer work synergistically. Compared with a single epoxy resin coating, the damping loss factor is significantly improved. Moreover, the coating is firmly bonded to the roughened metal lattice core layer and is not easy to fall off under vibration and impact environments. The vibration reduction and noise reduction effect is long-lasting and stable, which can meet the stringent requirements for vibration control in scenarios such as building vibration isolation and lightweight transportation vehicles.

[0019] The cell configuration (concave hexagon, double-arrow shape, etc.) and Poisson's ratio parameter (zero Poisson's ratio to -0.3) of the metal lattice core layer in this application can be flexibly designed through a three-dimensional model. Furthermore, a topology-optimized functional gradient structure can be used to further adapt to stress distribution. The type of metal nanoparticles, the core-shell coating ratio, and the resin matrix formulation can be adjusted according to application requirements to meet the performance requirements of different fields such as construction, transportation, and high-end equipment protection. Moreover, while ensuring high performance, this application effectively reduces the surface density of the material through the low-density design of the negative Poisson's ratio lattice (relative density 10%-20%), the ultra-thin coating of the core-shell damping coating (50-200μm), and optional chemical foaming agent-modified resin. This results in significant weight reduction compared to traditional seismic materials such as steel and concrete, reducing the self-weight of building structures, energy consumption of transportation vehicles, and transportation costs of equipment, thus possessing both economic value and environmental significance.

[0020] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description and claims. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Example 1 Preparation of in-situ composite carbon fibers with metal nanoparticles: Zinc nitrate hexahydrate was used as the zinc source, and N,N-dimethylformamide was used as the solvent. Zinc nitrate and polyacrylonitrile were mixed at a mass ratio of 10:90 (zinc nitrate mass fraction 10%, polyacrylonitrile mass fraction 9%) and stirred thoroughly until completely dissolved to prepare a homogeneous spinning solution. Precursor fiber membranes were prepared by electrospinning (voltage 18kV, receiving distance 15cm, feed speed 0.8mL / h). The precursor fiber membranes were pre-oxidized at 250℃ in air for 2 hours, followed by calcination at 1000℃ for 2 hours under argon protection to obtain carbon fibers (particle size 10-30nm) in-situ composite with zinc nanoparticles.

[0023] Fabrication of a negative Poisson's ratio metal lattice core layer: Based on a three-dimensional model of a concave hexagonal cell, a negative Poisson's ratio lattice plate (Poisson's ratio -0.2) with a relative density of 15% was printed using laser selective melting technology and aluminum-silicon alloy powder as raw material. After printing, the core layer was sandblasted, and the surface roughness Ra after treatment was 2.0 μm.

[0024] Preparation of functional damping coatings: Preparation of core-shell emulsions (using stepwise emulsion polymerization method) Core layer polymerization: 100 parts butyl acrylate, 2 parts methyl methacrylate (core layer monomer mixture), 3 parts emulsifier (sodium alkylbenzene sulfonate) and 150 parts deionized water were added to the reactor, stirred evenly, and heated to 75°C. 0.5 parts potassium persulfate initiator were added, and the mixture was kept at the temperature for 2 hours to obtain the core layer emulsion. Shell polymerization: A pre-emulsion consisting of 30 parts epoxy resin monomer (bisphenol A type epoxy resin E-51), 1 part emulsifier, and 50 parts deionized water was slowly added dropwise to the above core emulsion, while simultaneously adding 0.3 parts potassium persulfate initiator. The addition was controlled to be completed within 2 hours, and polymerization was continued at 85°C for 2 hours. After the reaction was completed, the mixture was cooled and discharged to obtain an epoxy resin / acrylate core-shell emulsion (core-shell mass ratio of 4:1, solid content of approximately 40%). Coating and curing: The epoxy resin / acrylate core-shell emulsion was uniformly coated onto the surface of the metal lattice core layer by spraying, with a coating thickness of 100 μm, and then cured at 80°C for 1 hour.

[0025] Integral composite molding: Two sheets of the aforementioned zinc nanoparticle-doped carbon fiber cloth are laid in a mold as the top and bottom panels, with a coated metal lattice core layer placed in the middle to form a preform. Vacuum-assisted resin transfer molding is used, injecting an epoxy resin system containing 1% azodicarbonamide foaming agent (E-51 epoxy resin and curing agent are mixed at a ratio of 100:30) under a vacuum of -0.08 MPa. The mold is then placed in a hot press and cured at 120°C and 0.6 MPa for 3 hours. After demolding, a standard sample is obtained.

[0026] Example 2 The standard sample was prepared according to the method of Example 1, but the difference from Example 1 is as follows: The core layer adopts a topology-optimized titanium alloy gradient lattice structure (the Poisson's ratio in the core is -0.1, gradually decreasing to 0.1 towards the edge).

[0027] Carbon fiber cloth was prepared by using copper acetate precursor to prepare carbon fibers in situ composited with copper nanoparticles.

[0028] No foaming agent is added to the resin system.

[0029] Example 3 The standard sample was prepared according to the method of Example 1, except that a metal lattice core layer with a Poisson's ratio of 0 was used in this example: The process for preparing a metal lattice core layer with a Poisson's ratio of 0 is as follows: Based on a three-dimensional model of an equilateral triangular cell, a triangular lattice structure with a relative density of 15% and a Poisson's ratio of 0 is printed using selective laser melting (SLM) with aluminum-silicon alloy powder as the raw material. After printing, the core layer is sandblasted, resulting in a surface roughness Ra of 2.0 μm.

[0030] Example 4 Preparation of in-situ composite carbon fibers with metal nanoparticles: Silver nitrate was used as the silver source, and N,N-dimethylformamide was used as the solvent. A spinning solution was prepared by mixing the silver source and polyacrylonitrile at a mass ratio of 12:88 (silver source mass fraction 12%, polyacrylonitrile mass fraction 11%). Electrospinning parameters were: voltage 18 kV, receiving distance 15 cm, and feed rate 0.8 mL / h. The precursor fiber membrane was pre-oxidized at 260 °C for 1.5 h and calcined at 1100 °C under argon protection for 1.5 h to obtain in-situ composite carbon fibers with silver nanoparticles (particle size 15-40 nm).

[0031] Preparation of a negative Poisson's ratio metal lattice core layer: A magnesium alloy lattice structure with double-arrow-shaped cells was adopted, with a relative density of 12% and a Poisson's ratio of -0.25. After being formed by precision sheet metal folding, it was sandblasted to achieve a surface roughness Ra of 1.8 μm.

[0032] Preparation of functional damping coating: Core-shell emulsion preparation: The core layer is isooctyl acrylate (100% by mass), and the emulsifier is sodium alkylbenzene sulfonate (3.5% by mass), polymerized at 75℃ for 1.5 hours; the shell layer is epoxy resin with a mass ratio of 5:1 to the core layer, polymerized at 90℃ for 2.5 hours. The emulsion is applied by spraying, with a coating thickness of 80 μm, and cured at 120℃ for 0.5 hours.

[0033] Integral composite molding: After assembling the preform, an epoxy resin system containing 2% sodium bicarbonate foaming agent is injected using a vacuum-assisted resin transfer molding process (vacuum degree -0.07MPa). The mixture is cured at 110℃ and 0.5MPa for 4 hours, and then demolded to obtain the sample.

[0034] Example 5 Preparation of in-situ composite carbon fibers with metal nanoparticles: A spinning solution was prepared using nickel nitrate as the nickel source and N,N-dimethylformamide as the solvent, with a nickel source to polyacrylonitrile mass ratio of 9:91 (9% nickel source, 10% polyacrylonitrile). Electrospinning parameters were: voltage 18 kV, receiving distance 15 cm, and feed rate 0.8 mL / h. The precursor fiber membrane was pre-oxidized at 250 °C for 2 hours and calcined at 1050 °C under argon protection for 2 hours to obtain carbon fibers (particle size 12-35 nm) in situ composited with nickel nanoparticles.

[0035] Preparation of a negative Poisson's ratio metal lattice core: A gradient lattice structure of aluminum alloy with topology optimization design was adopted, with a Poisson's ratio of -0.3 in the core, gradually decreasing to 0.1 towards the edge, and a relative density of 16%. After laser selective melting, the core was sandblasted to a surface roughness of Ra=2.2μm.

[0036] Application of the functional damping coating: A core-shell emulsion (core-shell mass ratio 5:1, core layer butyl acrylate / methyl methacrylate = 8:2, shell layer epoxy resin) was prepared by stepwise emulsion polymerization with 3% emulsifier. Core polymerization was carried out at 70℃ for 2 hours, followed by shell polymerization at 85℃ for 3 hours to obtain an epoxy resin / acrylate core-shell emulsion. The epoxy resin / acrylate core-shell emulsion was then uniformly coated onto the surface of the metal lattice core layer by spraying, with a coating thickness of 150 μm, and cured at 90℃ for 1.2 hours.

[0037] Integral composite molding: Vacuum-assisted resin transfer molding process (vacuum degree - 0.085MPa) is used to inject non-foaming agent epoxy resin, which is cured at 125℃ and 0.7MPa for 3 hours, and then demolded to obtain the sample.

[0038] Example 6 Preparation of carbon fibers in situ incorporating metal nanoparticles: Zinc nitrate hexahydrate was used as the zinc source, with a zinc source mass fraction of 11% and a polyacrylonitrile mass fraction of 10% in the spinning solution. The electrospinning voltage was 21 kV, the receiving distance was 13 cm, and the feed rate was 0.6 mL / h. Pre-oxidation was performed at 230℃ for 2.5 hours, followed by calcination at 950℃ under argon for 2.5 hours to obtain carbon fibers in situ incorporating zinc nanoparticles (zinc nanoparticle size 8-28 nm).

[0039] Preparation of a negative Poisson's ratio metal lattice core layer: a double-arrow-shaped cellular magnesium alloy lattice with a relative density of 14% and a Poisson's ratio of -0.28. After precision sheet metal folding and forming, chemical etching (immersion in 3% sulfuric acid solution for 8 minutes) was performed, resulting in a surface roughness Ra=1.6μm.

[0040] Preparation of functional damping coating: Core-shell emulsion with a core-shell mass ratio of 3:1, the core layer being ethyl acrylate and the shell layer being epoxy resin. Impregnation coating was performed to a thickness of 90 μm, and curing was carried out at 110℃ for 0.8 hours.

[0041] Integral composite molding: Vacuum degree - 0.075MPa, inject epoxy resin containing 0.8% sodium bicarbonate foaming agent, cure at 105℃ and 0.9MPa for 3.5 hours, and demold to obtain the sample.

[0042] Comparative Example 1 The difference from Example 1 is that the core layer uses a traditional hexagonal honeycomb structure aluminum alloy core material (Poisson's ratio 0.3), while the rest of the preparation steps are the same as in Example 1.

[0043] Comparative Example 2 The difference from Example 1 is that the step of applying the functional damping coating is omitted, and no damping coating is applied to the surface of the metal lattice core layer. The remaining preparation steps are the same as in Example 1.

[0044] Comparative Example 3 The difference from Example 1 is that the carbon fiber panel uses commercial T300 carbon fiber plain weave fabric that has not been modified with any metal nanoparticles, while the rest of the preparation steps are the same as in Example 1.

[0045] Comparative Example 4 The difference from Example 1 is that the carbon fiber panel does not use an in-situ composite process. Instead, zinc nanoparticles (particle size 10-30nm) are directly mixed into the epoxy resin matrix (mass fraction is the same as in Example 1), and then commercial T300 carbon fiber cloth is impregnated to prepare the panel. The remaining steps are exactly the same as in Example 1.

[0046] Comparative Example 5 The difference from Example 1 is that the functional damping coating does not use a core-shell structure, but directly uses a pure epoxy resin coating (with the same amount of epoxy resin as in the core-shell emulsion of Example 1), with a coating thickness of 100 μm, cured at 80°C for 1 hour, and the remaining steps are the same as in Example 1.

[0047] Comparative Example 6 (Negative Poisson's Ratio Non-Gradient Structure, in contrast to gradient design innovation) The difference from Example 1 is that the metal lattice core layer has a uniform negative Poisson ratio structure (overall Poisson ratio is -0.1, with no gradient change), while the rest of the preparation steps are exactly the same as in Example 1.

[0048] The samples prepared in the above embodiments and comparative examples were subjected to performance tests, including areal density, three-point bending strength, drop weight impact energy absorption, damping loss factor, and interlaminar shear strength. The test methods are as follows: 1. Surface density test (kg / m³) 2 Reference standards: GB / T 451.3-2002 "Determination of thickness of paper and paperboard" and GB / T 1033.1-2008 "Determination of density of non-foamed plastics - Part 1: Impregnation method, liquid pyrometer method and titration method".

[0049] 2. Three-point bending strength test (MPa): Reference standard: GB / T 1449-2005 "Test method for bending properties of fiber reinforced plastics" 3. Drop hammer impact energy absorption test (J / g): Reference standard: GB / T 1843-2008 "Determination of impact strength of plastic cantilever beams" (Modified for energy absorption calculation).

[0050] 4. Damping loss factor test: Reference standard: GB / T 22315-2008 "Test method for elastic modulus and Poisson's ratio of metallic materials" (dynamic mechanical analysis correction method) 5. Interlaminar shear strength test (MPa): Reference standard: GB / T 1450.1-2005 "Test method for interlaminar shear strength of fiber reinforced plastics".

[0051] The test results are shown in Table 1: Table 1

[0052] As can be seen from Table 1, the energy absorption values ​​of Examples 1 and 2 are about 40% higher than those of Comparative Example 1, proving that the negative Poisson's ratio structure can dissipate energy more effectively through lateral expansion deformation under impact, and its seismic and impact resistance performance is significantly better than that of the traditional honeycomb structure.

[0053] The damping loss factor of Example 1 is much higher than that of Comparative Example 2, indicating that the nano-core-shell damping coating can significantly improve the vibration reduction and noise reduction capabilities of the structure, which is crucial for earthquake resistance and comfort.

[0054] The interlaminar shear strength of Example 1 is higher than that of Comparative Example 3, indicating that the in-situ generated metal nanoparticles form a stronger bond between the fiber and the resin, effectively improving the overall integrity and load-bearing capacity of the material.

[0055] The interlayer shear strength of Comparative Example 4 (non-in-situ doping) of 24.1 MPa is much lower than that of Example 1 (28.7 MPa), which proves that the in-situ composite metal nanoparticles of this application can form stronger micro-anchors and solve the problem of weak interfacial bonding caused by traditional physical mixing.

[0056] The damping loss factor of Comparative Example 5 (pure epoxy resin coating) was 0.041, which was only 48% of that of Example 1 (0.085), and the impact energy absorption was significantly reduced. This verifies that the epoxy resin / acrylate nano core-shell structure improves the damping performance through the synergistic effect of the core and shell, rather than the simple effect that can be achieved by a single coating.

[0057] The impact energy absorption of Comparative Example 6 (non-gradient negative Poisson's ratio structure) was 44.7 J / g, which was lower than that of Example 2 (48.3 J / g), indicating that the gradient design can more accurately control the stress distribution and further improve the energy dissipation efficiency.

[0058] Multi-parameter synergistic performance improvement: The comprehensive performance (bending strength, impact absorption, damping factor) of Examples 5 (gradient structure + optimized core-shell ratio) and 6 (process optimization + magnesium alloy core layer) is better than that of the basic examples, proving that the innovation of this application is not limited to a single element, but is the synergistic effect of multiple parameters and multiple conditions.

[0059] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A lightweight, earthquake-resistant composite material, characterized in that, It is a sandwich structure, including: Both the upper and lower panels are made of resin matrix and reinforcing material through impregnation; the reinforcing material is carbon fiber with in-situ composite metal nanoparticles. The intermediate core layer is a metal lattice structure with zero Poisson ratio or negative Poisson bit characteristics, which is disposed between the upper panel and the lower panel; the surface of the metal lattice structure is coated with a functional damping coating.

2. The lightweight earthquake-resistant composite material according to claim 1, characterized in that, The metal nanoparticles are copper, zinc, silver or nickel nanoparticles with a particle size of 5-50 nm. The metal lattice structure is made of aluminum alloy, titanium alloy or magnesium alloy.

3. The lightweight earthquake-resistant composite material according to claim 1, characterized in that, The functional damping coating is a nano core-shell structure formed by epoxy resin / acrylate, and the coating thickness is 50-200μm. The core layer of the nano-core-shell structure is an acrylate elastomer, and the shell layer is an epoxy resin, with a mass ratio of core layer to shell layer of 3:1-5:

1.

4. The lightweight earthquake-resistant composite material according to any one of claims 1-3, characterized in that, The cell configurations of the metal lattice structure include concave hexagons, double-arrow shapes, triangles, chiral structures, or functional gradient structures designed through topology optimization. In this design, the Poisson's ratio of the functionally graded structure, which is designed through topology optimization, gradually changes from -0.1 to -0.3 in the core of the metal lattice structure to 0 to 0.1 towards the edge of the structure.

5. The lightweight earthquake-resistant composite material according to any one of claims 1-3, characterized in that, The resin matrix is ​​epoxy resin; Alternatively, the resin matrix may be an epoxy resin with added chemical foaming agent, wherein the amount of chemical foaming agent added accounts for 0.5-2% of the total amount of epoxy resin; The chemical foaming agent is azodicarbonamide or sodium bicarbonate.

6. A method for preparing a lightweight earthquake-resistant composite material, characterized in that, The method for preparing the composite material according to any one of claims 1-5 comprises the following steps: Preparation of carbon fibers in situ composited with metal nanoparticles: a spinning solution containing a metal source and a carbon fiber precursor is electrospinned to form a precursor fiber membrane. The precursor fiber membrane is then subjected to pre-oxidation treatment and high-temperature calcination treatment under an inert atmosphere to obtain carbon fibers in situ composited with metal nanoparticles. Fabrication of a negative Poisson's ratio metal lattice core layer: Based on a pre-defined three-dimensional model, a metal lattice structure with zero or negative Poisson's ratio characteristics is fabricated, and its surface is roughened. Applying a functional damping coating: applying damping material to the roughened surface of the metal lattice structure, and curing it to form a functional damping coating. Composite curing molding: The carbon fiber in situ composited with metal nanoparticles is used as the panel, and a metal lattice structure with a functional damping coating cured on the surface is placed between the upper panel and the lower panel as the core layer. A resin matrix is ​​introduced, and the composite material is obtained by vacuum-assisted impregnation and molding curing.

7. The method according to claim 6, characterized in that, In the process of preparing metal nanoparticle-doped carbon fiber preforms The metal source is zinc nitrate, copper acetate, silver nitrate, or nickel nitrate; The carbon fiber precursor is polyacrylonitrile; The metal source in the spinning solution has a mass fraction of 5-15%, and the polyacrylonitrile mass fraction has a mass fraction of 8-12%. The pre-oxidation treatment conditions are 220-280℃ for 1.5-2.5 hours; The conditions for the high-temperature calcination treatment are calcination at 800-1200℃ for 1.5-2.5 hours.

8. The method according to claim 6, characterized in that, In the process of preparing the negative Poisson's ratio metal lattice core layer, the roughening treatment is sandblasting or chemical etching, and the surface roughness Ra of the metal lattice structure after treatment is 1.5-3.0 μm.

9. The method according to claim 6, characterized in that, During the application of the functional damping coating, The damping material is prepared by a stepwise emulsion polymerization method, specifically: Using acrylate monomers as the core layer raw material, an emulsion is formed under the action of an emulsifier, and then epoxy resin monomers are added for shell layer polymerization to obtain an epoxy resin / acrylate core-shell emulsion. An epoxy resin / acrylate core-shell emulsion is uniformly coated onto the surface of a metal lattice core layer by spraying, and a functional damping coating is obtained after curing at 80-120℃ for 0.5-2 hours. The acrylate monomers include one or more combinations of butyl acrylate, methyl methacrylate, and isooctyl acrylate.

10. The method according to claim 6, characterized in that, During the composite curing and molding process, The vacuum-assisted impregnation process employs a vacuum-assisted resin transfer molding process with a vacuum degree of -0.09 to -0.07 MPa. The molding curing conditions are: temperature 100-140℃, pressure 0.5-1.0MPa, and time 2-4 hours.

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