Composite material thermal forming method based on thermal activation topology reconstruction
Through the thermally activated topological reconstruction method, combined with interface modification and multi-physics field assistance, the problems of internal residual stress and low interface performance of composite material blanks were solved, and high-strength and high-precision composite material forming was achieved, which is suitable for aerospace components.
Patent Information
- Application Number
- CN202510723949.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-02
- Publication Date
- 2025-10-17
AI Technical Summary
Existing thermoforming technology improves interface properties through a multi-step curing process, but it leads to problems of residual stress inside the composite blank and low interface performance.
A thermally activated topological reconstruction method is adopted, including material pretreatment, topological structure design, thermal activation stage, dynamic reconstruction forming and topological locking steps, combined with interface modification technologies such as silane coupling agent and oxygen plasma treatment, and coordinated with multi-physical field assistance to achieve dynamic rearrangement of the reinforcement phase and precise topological structure formation.
The interface performance and forming accuracy of composite materials have been significantly improved. The carbon fiber interface shear strength has increased by 36.8% to 52MPa, and the aramid fiber interlayer shear strength has increased by 45% to 46MPa. The forming error is ≤0.8%, the bending modulus reaches 45GPa, and the shape recovery rate is ≥92%, meeting the high performance requirements of aerospace components.
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Figure CN120792192A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of hot forming, in particular to a composite material hot forming method based on thermal activation topological reconstruction. BACKGROUND
[0002] Hot forming technology is an advanced manufacturing process that heats metal plates to the austenitizing temperature interval and keeps them for a certain time, softens the material, quickly puts it into the mold for stamping forming, and quenches the formed parts through the cooling system inside the mold, thereby obtaining parts with high strength and high dimensional accuracy. Composite material hot forming technology is a key process in the fields of aerospace, automobile manufacturing, etc.
[0003] The existing hot forming technology improves the interface performance by adopting a multi-step curing process, but the unmodified reinforcing phase (such as carbon fiber, ceramic particles) has weak interfacial bonding with the matrix, resulting in internal residual stress of the blank and low interface performance. SUMMARY
[0004] In view of the shortcomings of the prior art, the present application provides a composite material hot forming method based on thermal activation topological reconstruction, which solves the problem of internal residual stress of the blank and low interface performance caused by the existing hot forming technology by adopting a multi-step curing process to improve the interface performance.
[0005] To achieve the above purpose, the present application is implemented by the following technical scheme: a composite material hot forming method based on thermal activation topological reconstruction, comprising the following steps:
[0006] S1, material pretreatment: preparing a composite material blank containing a thermal activation matrix and a reinforcing phase, and performing interface modification treatment on the reinforcing phase;
[0007] S2, topological structure design: applying pre-deformation to the blank above the glass transition temperature of the matrix material, forming a temporary topological configuration by mold constraint, and then programmed cooling to lock stress;
[0008] S3, thermal activation stage: heating the programmed blank to an activation temperature interval, wherein the temperature interval is at the transition temperature to the transition temperature + 50℃, and applying an external field for assistance;
[0009] S4, dynamic reconstruction forming: guiding the dynamic rearrangement of material molecular chains and reinforcing phase in the thermal activation state to form a target topological structure;
[0010] S5, topological locking: fixing the reconstructed topological structure by gradient cooling or cross-linking curing;
[0011] S6, post-processing and verification: machining and performance testing of the formed part.
[0012] By the above technical solution, the polyimide powder is dissolved in NMP solvent, the solid content is adjusted to 25%-30%, it is fully dissolved after constant temperature stirring at 80℃ for 4 hours, film forming is carried out by using flow casting process, and then uniform film with thickness of 0.2-0.5mm is obtained through vacuum dehydration treatment; for shape memory epoxy resin, the epoxy resin is mixed with DDM curing agent at mass ratio of 10:1, and 0.5% carbon nanotube is added to improve the thermal conductivity, the resin is fully impregnated into carbon fiber fabric through impregnation process, and B-stage prepreg is prepared by pre-curing at 80℃ for 2 hours; and for polyether ether ketone-based composite material, high temperature melting process is used, PEEK raw material and 20%-40% Si3N4 reinforcing phase are high temperature melted and blended in a double screw extruder at 380℃, and then mold forming is carried out to ensure that the material fully flows and uniformly distributes.
[0013] Preferably, in S1, the heat-activated matrix is thermoplastic polyimide, shape memory epoxy resin or polyether ether ketone, the reinforcing phase is at least one of continuous carbon fiber, aramid fiber or silicon nitride particles, and the surface of the reinforcing phase is treated by silane coupling agent or oxygen plasma.
[0014] Preferably, in S2, the programmed cooling rate is 2-8℃ / min, and the constraint pressure of 0.5-5MPa is applied to the blank by the mold during the cooling process.
[0015] Preferably, in S3, the external field assistance includes at least one of the following:
[0016] Mechanical pressure: applied by air pressure or hydraulic pressure, pressure range is 0.5-8MPa;
[0017] Electric field: field strength is 1-10kV / mm, frequency is 50Hz-1kHz;
[0018] Magnetic field: magnetic induction intensity is 0.1-2T.
[0019] Preferably, in S4, the strain rate of dynamic reconfiguration forming is controlled in the range of 5×10-3-5×10-2s-1, and the guiding mode of the target topological structure includes:
[0020] Mold cavity geometric constraint;
[0021] Reinforcing phase preset gradient distribution and thermal expansion coefficient difference synergistic control;
[0022] External stress field direction and reinforcing phase orientation matching.
[0023] Preferably, in S5, the gradient cooling rate is 1-3℃ / min, and the crosslinking and curing are triggered by UV irradiation or thermal initiator, the UV irradiation wavelength is 300-400nm, and the irradiation dose is 20-80mJ / cm 2.
[0024] Preferably, in the S6, the performance test comprises:
[0025] Microstructure analysis: observe the distribution of reinforcing phase and interface bonding state by micro-CT or scanning electron microscopy (SEM);
[0026] Mechanical property test: determine the bending strength, interlaminar shear strength and anisotropic modulus;
[0027] Shape stability verification: cycle loading 3-5 times in the environment of the transformation temperature ±10℃, and the shape recovery rate is ≥90%.
[0028] Preferably, the same blank is reconstructed multiple times by repeating S3-S5, and the shape recovery rate after each reconstruction attenuates by ≤5%.
[0029] Preferably, the composite material has a spatial gradient topology structure, the local reinforcing phase volume fraction continuously changes in the range of 10%-60%, and presents a controllable anisotropic mechanical response under different temperature activation conditions.
[0030] Preferably, in S4, the material strain field distribution is monitored based on infrared thermal imaging or optical fiber sensors, and the external field auxiliary parameters are dynamically adjusted to ensure that the forming precision error of the target topology structure is ≤1.5%.
[0031] The application provides a composite material hot forming method based on thermal activation topology reconstruction.
[0032] The application has the following beneficial effects:
[0033] 1、The application adopts interface modification technologies such as silane coupling agent treatment of carbon fibers, oxygen plasma treatment of silicon nitride particles, and two-step treatment of aramid fibers, and combines an optimized matrix composite process, so that the carbon fiber interface shear strength is increased by 36.8% to 52 MPa, the aramid fiber interlaminar shear strength is increased by 45% to 46 MPa, and the porosity of the composite material is controlled in the range of 0.3%-0.5%, thereby providing a blank basis with high bonding strength and low defects for subsequent hot forming and improving the interface performance.
[0034] 2、The application precisely controls the mold constraint pressure through programmed cooling and cooperates with multi-physical field auxiliary assistance, so that the tensile strength of carbon fiber / PEEK is increased by 50% to 650 MPa, the order degree of barium titanate particles reaches 88%, the crystal plane orientation degree of carbonyl iron powder (110) is increased to 75%, and the residual stress increase is controlled within 40%, and the fiber breakage rate is less than 5%, thereby achieving the effect of precise regulation of the microstructure of the material.
[0035] 3、The application controls the strain rate through servo driving mold, combines the synergistic guidance of invar alloy cavity, gradient distribution design of reinforcing phase and dynamic adjustment of stress field direction of six-axis mechanical arm, so that the forming error is less than or equal to 0.8%, the strain uniformity of the wave structure with a curvature radius of 5-20mm is greater than or equal to 92%, the bending modulus reaches 45GPa, the molecular chain disentanglement efficiency is greater than 80%, and the porosity is less than 2%, and high-precision forming is realized.
[0036] 4、The application promotes the carbon fiber / epoxy bending strength to reach 620MPa through the synergistic effect of 1-3℃ / min gradient cooling and controllable curing process, which is 40% higher than that of the traditional process, the shape recovery rate is maintained above 92% for 5 cycles, the curing degree is greater than or equal to 90%, the interlaminar shear strength is 55MPa, the variation coefficient of the reinforcing phase distribution is less than or equal to 8% according to the two micro-CTs, the requirements of durability and SEM observation of anisotropy are met, and the effect of high-performance topological locking is realized. BRIEF DESCRIPTION OF DRAWINGS
[0037] Figure 1 A process flow chart of a composite material hot forming method based on thermal activation topological reconstruction is provided. DETAILED DESCRIPTION
[0038] The technical solutions of the application will be described clearly and completely below with reference to the drawings of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.
[0039] Please refer to the drawings of the application Figure 1 A composite material hot forming method based on thermal activation topological reconstruction, comprising the following steps:
[0040] S1, material pretreatment: preparing a composite material blank containing a thermal activation matrix and a reinforcing phase, and performing interface modification treatment on the reinforcing phase;
[0041] S2, topological structure design: applying pre-deformation to the blank above the glass transition temperature of the matrix material, forming a temporary topological configuration through mold constraint, and then programming cooling to lock stress;
[0042] S3, thermal activation stage: heating the programmed blank to an activation temperature interval, wherein the temperature interval is at the transition temperature to the transition temperature+50℃, and an external field is applied for assistance;
[0043] S4, dynamic reconstruction forming: guiding the dynamic rearrangement of the molecular chains and the reinforcing phase of the material in the thermal activation state to form a target topological structure;
[0044] S5, Topology locking: fixing the reconfigured topology by gradient cooling or crosslinking solidification;
[0045] S6, Post-processing and verification: machining and performance testing of the formed part.
[0046] In S1, the heat-activated matrix is thermoplastic polyimide, shape memory epoxy resin or polyether ether ketone, the reinforcing phase is at least one of continuous carbon fiber, aramid fiber or silicon nitride particles, and the surface of the reinforcing phase is treated with silane coupling agent or oxygen plasma.
[0047] In S2, the programmed cooling rate is 2-8℃ / min, and the mold applies a restraining pressure of 0.5-5MPa to the blank during cooling.
[0048] In S3, the external field assistance includes at least one of:
[0049] Mechanical pressure: applied by air pressure or hydraulic pressure, pressure range 0.5-8MPa;
[0050] Electric field: field strength 1-10kV / mm, frequency 50Hz-1kHz;
[0051] Magnetic field: magnetic induction intensity 0.1-2T.
[0052] In S4, the strain rate of dynamic reconfiguration forming is controlled within the range of 5×10-3-5×10-2s-1, and the guiding mode of the target topology structure includes:
[0053] Mold cavity geometric constraint;
[0054] Reinforcing phase preset gradient distribution and thermal expansion coefficient difference synergistic control;
[0055] External stress field direction and reinforcing phase orientation matching.
[0056] In S5, the gradient cooling rate is 1-3℃ / min, and the crosslinking solidification is triggered by UV irradiation or thermal initiator, the UV irradiation wavelength is 300-400nm, and the irradiation dose is 20-80mJ / cm 2 .
[0057] In S6, the performance test includes:
[0058] Microstructure analysis: observing the reinforcing phase distribution and interface bonding state by micro-CT or scanning electron microscope (SEM);
[0059] Mechanical property testing: determining the bending strength, interlaminar shear strength and anisotropic modulus;
[0060] Shape stability verification: cyclic loading 3-5 times in an environment of ±10℃ of the transformation temperature, shape recovery rate ≥90%.
[0061] The same blank is subjected to multiple topological structure reconstruction by repeating S3-S5, and the shape recovery rate after each reconstruction is attenuated by ≤5%.
[0062] The composite material has a spatial gradient topological structure, the local reinforced phase volume fraction of which continuously changes in the range of 10%-60%, and exhibits controllable anisotropic mechanical response under different temperature activation conditions.
[0063] In S4, the material strain field distribution is monitored based on infrared thermal imaging or optical fiber sensors, and the external field auxiliary parameters are dynamically adjusted to ensure that the forming precision error of the target topological structure is ≤1.5%.
[0064] Specifically, thermoplastic polyimide powder is dissolved in N-methyl pyrrolidone by solution casting method, the solid content is controlled to be 25%-30%, then after stirring at 80℃ for 4 hours, a 0.2-0.5mm thin film is formed to avoid film forming defects; the shape memory epoxy resin matrix is prepared by mixing epoxy resin and 4,4'-diaminodiphenyl methane (mass ratio 10:1), and adding 0.5wt% carbon nanotube to enhance the thermal conductivity, then impregnating carbon fiber cloth, pre-curing at 80℃ for 2h, and forming B-stage prepreg; and the polyether ether ketone matrix is prepared by melt blending method, polyether ether ketone particles and 20%-40% silicon nitride particles are blended in a double screw extruder at 380℃, and then molded to ensure that the melt flows sufficiently;
[0065] After the continuous carbon fiber is treated with 3% KH550 silane solution at pH=4.5 and 60℃ for 30 minutes, the interfacial shear strength is increased from 38MPa to 52MPa, and the contact angle is reduced from 120° to 40°; after the silicon nitride particles are treated by oxygen plasma, the surface oxygen content is increased from 12% to 28%, and the bonding energy with polyether ether ketone is increased to 1.8J / m2; the aramid fiber is treated by a two-step method of plasma activation and KH560 silane treatment, the interlaminar shear strength is increased by 45% to 46MPa, and the surface roughness is increased from 15nm to 85nm; during the blank forming stage, the carbon fiber prepreg is laid in 0° / 90° cross pattern and vacuum bagged (porosity ≤0.3%); the particle reinforced blank is uniformly dispersed by ultrasonic dispersion, the interface performance between the treated carbon fiber and Si3N4 / PEEK is optimized, and the porosity is reduced to 0.3%-0.5%;
[0066] The PID temperature control system is used to reduce the temperature at a rate of 2-8 ℃ / min, while the hydraulic device is used to maintain the constraint pressure of 0.5-5 MPa on the blank by the mold, the mold is made of Invar alloy (CTE≤1.5×10-6 / ℃) with low thermal expansion coefficient to ensure the dimensional stability of the cavity; the X-ray residual stress analyzer is used to monitor in real time during the cooling process, the results show that when the rate is >8 ℃ / min, the internal residual stress of the blank increases by 40%, and when the rate is <2 ℃ / min, the energy consumption increases by 2 times and the production efficiency decreases; the constraint pressure is optimized by finite element simulation, when the pressure is <0.5 MPa, the springback rate of the blank is 15%, and when the pressure is >5 MPa, the fiber is broken;
[0067] The external field assisted dynamic response of the material is controlled by multi-physical field coupling: the hydraulic system (precision ±0.1 MPa) is used to apply a pressure of 0.5-8 MPa (preferably 5 MPa), the pressure direction is 30°-60° to the fiber axial direction to promote the molecular chain slip and enhance the synergistic orientation (finite element simulation shows that when the pressure is <0.5 MPa, the material density is insufficient, the porosity is >2%, and when the pressure is >8 MPa, the fiber breakage rate is >5%); the electric field assisted is applied by parallel plate electrodes with a field strength of 1-10 kV / mm (frequency 50 Hz-1 kHz), for composite materials containing barium titanate (BaTiO3) particles, the dielectrophoresis effect is significant under the condition of 500 Hz / 5 kV / mm, SEM observation shows that the particle arrangement order along the electric field line is 88% (the untreated group is only 35%), and the dielectric spectrum test shows that the dielectric loss factor tanδ peak value (0.15) at this frequency avoids overheating; the magnetic field assisted is generated by an electromagnetic coil with a magnetic induction intensity of 0.1-2 T (preferably 1 T), for the carbonyl iron powder reinforced system, the magnetic field makes the particles form a chain structure (XRD shows that the (110) crystal plane orientation degree is improved to 75%), and the magnetic field induced Lorentz force makes the matrix rheological storage modulus decrease by 40% (rheometer test, strain rate 0.01 s -1 ), promoting the rearrangement of molecular chains. The implementation effect verification shows that when the 5 MPa pressure and 1 T magnetic field are synergistically applied, the tensile strength of the carbon fiber / PEEK composite material is improved to 650 MPa (50% higher than that without external field), and the particle distribution uniformity (coefficient of variation <8%) under the electric field-pressure coupling meets the high-precision device requirements. Parameter optimization is based on breakdown field strength test (>12 kV / mm dielectric breakdown occurs) and magnetic saturation curve (>2 T magnetization increases by <5%), ensuring efficient and safe external field assistance;
[0068] The dynamic reconfiguration forming stage realizes the target topology through precise strain rate control (5x10-3~5x10-2s-1) and multi-factor synergistic guidance: the servo-driven mold (displacement resolution 0.1 μm) is used to control the strain rate, and the rheological test shows that the range can balance the molecular chain disentanglement efficiency (>80%) and defect suppression, that is, when the strain rate is greater than 5x10-2s-1, the porosity is greater than 2%, and when the strain rate is less than 5x10-3s-1, the energy consumption increases by 3 times; in the target structure guidance, the mold cavity is precisely machined (tolerance ±5 μm) with Invar alloy (CTE≤1.5x10-6 / ℃), combined with gradient preposition of reinforcing phase and difference in thermal expansion coefficient between matrix and reinforcing phase, after heating, a wave structure with a curvature radius of 5-20 mm is formed (DIC strain field analysis shows that the uniformity is greater than or equal to 92%); the direction of the external stress field is dynamically adjusted by a six-axis mechanical arm (the matching error with the fiber orientation is less than or equal to 2°), and finite element simulation shows that when the matching is 0°, the fiber slip rate is reduced by 70%; at the same time, the integrated fiber grating sensor (wavelength resolution 1 pm, sampling frequency 1 kHz) and infrared thermal imaging (accuracy ±0.5℃) are used to monitor the strain-temperature field in real time, and the pressure (±0.2 MPa) and heating power (±5%) are dynamically adjusted through the PID algorithm, so that the forming precision error is reduced from 3.2% to 0.8%, and the bending modulus of the gradient structure reaches 45 GPa through the ASTM D790 test;
[0069] The gradient cooling stage cools from the activation temperature to Tg-30℃ at a rate of 1-3℃ / min through a process-controlled annealing furnace, while maintaining the mold pressure at 0.5-5 MPa, and the temperature gradient is monitored by infrared thermal imaging to be less than or equal to 5℃ / mm, to ensure the ordered arrangement of molecular chains, and DSC shows that when the cooling rate is greater than 3℃ / min, the crystallinity decreases by 15%, and when the cooling rate is less than 1℃ / min, the energy consumption increases by 2 times; the crosslinking and curing of the photosensitive resin system uses a 365 nm UV-LED array (wavelength half-width ±10 nm) for irradiation, the dose is 20-80 mJ / cm 2 , the irradiation time is 10-30 minutes, and FTIR test shows that when the dose is less than 20 mJ / cm 2 , the double bond conversion rate is only 65%, and when the dose is greater than 80 mJ / cm2, surface yellowing (color difference ΔE>5) is caused; for the thermosetting system, dicumyl peroxide (DCP) is used as an initiator (addition amount 1-2 wt%), and crosslinking is triggered at 160-180℃ (TGA determines that the decomposition peak is 170℃), and the rheometer monitors that the storage modulus G' rises from 103 Pa to 10 5Pa (curing degree ≥ 90%), 2℃ / min gradient cooling combined with 50mJ / cm2 UV irradiation can make the bending strength of carbon fiber / epoxy composite material increase to 620MPa, which is 40% higher than that of traditional quenching process, and the shape recovery rate remains 92% after 5 cycles; while the interlaminar shear strength of DCP thermal curing system reaches 55MPa, and the porosity is ≤0.2%, which meets the performance requirements of high load structure and ensures the balance of topology locking efficiency and energy consumption;
[0070] Performance testing comprehensively evaluates material performance through cross-scale analysis: microstructure analysis uses high-resolution micro-CT (resolution 0.5μm, scanning voltage 80kV) to reconstruct the three-dimensional distribution of the reinforcing phase, and quantitatively calculates the local volume fraction variation coefficient ≤8%, while the untreated sample is >20%, and the interface bonding state is observed by field emission scanning electron microscope (SEM, acceleration voltage 15kV, working distance 10mm), which shows that there is no visible debonding between silane-treated carbon fiber and matrix; mechanical property testing is carried out by three-point bending test, with span ratio 16:1 and loading rate 2mm / min, and the bending strength of gradient composite material reaches 720MPa, while the isotropic sample is only 480MPa, the interlaminar shear strength is tested by short beam method and increased to 58MPa, the interface modification increases by 45%, and the anisotropic modulus is measured by biaxial extensometer (axial / transverse modulus ratio 18:1), which confirms the effectiveness of reinforcing phase orientation control; shape stability verification is carried out in a temperature-controlled fatigue testing machine, with Tg±10℃ cyclic loading for 5 times, the adjusted load is 80% of the yield strength, the frequency is 0.5Hz, and the digital image correlation (DIC) technology quantifies the shape recovery rate ≥93%, and the attenuation is ≤2.7% after the 5th cycle (SEM observation shows no micro-crack propagation), which meets the durability requirements of aerospace dynamic components.
[0071] Example one:
[0072] I. Technical solution:
[0073] 1. Material pretreatment:
[0074] Matrix: thermoplastic polyimide (TPI) is prepared into a film by solution casting method, using NMP as solvent, preparing TPI solution with solid content of 28%, uniformly coating the solution, and drying at 80℃ for 12 hours to form a film.
[0075] Reinforcing phase: T700 grade carbon fiber is treated with 3% KH550 silane, and then ultrasonic treated at pH=4.5, 60℃ for 30 minutes.
[0076] Blank forming: 0° / 90° cross-lamination, vacuum bag pressing (porosity 0.3%).
[0077] 2. Topology programming:
[0078] Pre-deformation temperature: Tg+20℃ (270℃), compression deformation 40%.
[0079] Programmed cooling: rate 2℃ / min, mold pressure 3MPa, mold is Invar alloy mold.
[0080] 3. Thermal activation and external field assistance:
[0081] Activation temperature: 270-320℃, hydraulic pressure 5MPa, 45° angle with fiber.
[0082] 4. Dynamic reconstruction:
[0083] In the dynamic reconstruction forming process, the servo-driven mold (displacement resolution 0.1 μm) is used to accurately control the strain rate of 1×10-2s-1, combined with the geometric constraint of the low thermal expansion coefficient Invar alloy mold cavity (tolerance ±5 μm), and through the preset carbon fiber volume fraction gradient (from 10% on the surface to 50% in the core, continuously increasing) and the difference in thermal expansion coefficient of the matrix, the laser displacement sensor is used to monitor the deformation in real time (accuracy ±0.1%), to ensure that the molecular chain disentanglement efficiency is >85% while the porosity is suppressed below 0.5%, and finally the shaped parts are verified by digital image correlation (DIC) technology, the strain uniformity is ≥92%, the bending modulus reaches 45GPa, realizing the integrated forming of high strength and lightweight gradient structure.
[0084] 5. Topological locking:
[0085] Gradient cooling rate 2℃ / min, UV curing (365nm, 50mJ / cm2).
[0086] II. Technical effect verification:
[0087] Microstructure: Micro-CT shows that the carbon fiber gradient distribution is uniform (coefficient of variation 5%), and the interface has no debonding (observed by SEM).
[0088] Mechanical properties: According to ASTM D790-17 standard, the bending strength of the sample of the embodiment is 720MPa, while the bending strength of the sample of the prior art is 480MPa; the short beam shear method is used to test the sample, the interfacial shear strength of the sample of the embodiment is 58MPa, while the interfacial shear strength of the sample of the prior art is 35MPa, and the anisotropic modulus ratio is 18:1.
[0089] Shape stability: shape recovery rate 93.5% after 5 cycles, attenuation amplitude 2.5%.
[0090] III. Conclusion: TPI-based composites realize high strength and high shape stability through gradient distribution and external field synergistic control, and are suitable for aerospace load-bearing components.
[0091] Example II:
[0092] I. Technical Solution:
[0093] 1. Material Pre-treatment:
[0094] Matrix: Shape memory epoxy resin (E51: 4,4'-diaminodiphenyl methane = 10:1, pre-cured 80°C / 2h).
[0095] Reinforcement: Aramid fibers treated by two steps of plasma (150W, 3min) and KH560 silane.
[0096] Blank forming: Unidirectional lay-up, prepreg resin content 42%.
[0097] 2. Topology Programming:
[0098] Pre-deformation temperature: Tg+15°C (95°C), bending deformation curvature radius 10mm.
[0099] Programmed cooling: rate 5°C / min, mold pressure 2MPa.
[0100] 3. Thermal Activation and External Field Assistance:
[0101] Activation temperature: 95-145°C, electric field assistance (5kV / mm, 500Hz).
[0102] 4. Dynamic Reconfiguration:
[0103] Strain rate 8x10-3s-1, external stress field and fiber orientation matching (error ≤1°).
[0104] 5. Topology Locking:
[0105] Gradient cooling rate 1.5°C / min, DCP thermal initiator (1.5wt%, 170°C curing).
[0106] II. Technical Effect Verification:
[0107] Microstructure: AFM shows fiber surface roughness 85nm, interlaminar shear strength 46MPa (improved by 45%).
[0108] Mechanical properties: bending strength 580MPa, anisotropic modulus ratio 12:1.
[0109] Shape stability: recovery rate 94.2% after 3 cycles, no interface cracks (SEM).
[0110] III. Conclusion: Aramid / epoxy resin system through plasma-silane synergistic treatment and electric field assistance, improves interface strength and shape memory performance, suitable for deformable satellite antennas.
[0111] Example Three:
[0112] I. Technical Solution:
[0113] 1. Material Preparation:
[0114] Matrix: PEEK with 30% silicon nitride particles melt blended (double screw extruder, 380°C).
[0115] Reinforcement: Silicon nitride particles treated with oxygen plasma (200W, 5 minutes).
[0116] Blank formation: Ultrasonic dispersion (500W, 40kHz), D50 = 15μm after sieving.
[0117] 2. Topology Programming:
[0118] Pre-deformation temperature: Tg + 25°C (168°C), with 30% thickness reduction.
[0119] Programmed cooling: Rate 8°C / min, mold pressure 4MPa.
[0120] 3. Thermal Activation and Field Assistance:
[0121] Activation temperature: 168-218°C, with magnetic field assistance (1T).
[0122] 4. Dynamic Reconstruction:
[0123] Strain rate 3x10-2s-1, thermal expansion coefficient difference induced self-organization structure (curvature radius 8mm).
[0124] 5. Topology Locking:
[0125] Gradient cooling rate 2.5°C / min, without additional curing (dependent on PEEK crystallinity).
[0126] II. Technical Effect Verification:
[0127] Microstructure: XPS shows 28% oxygen content on the surface of silicon nitride, interfacial binding energy 1.8J / m 2 .
[0128] Mechanical properties: Tensile strength 650MPa (50% higher than untreated), wear resistance increased by 60%.
[0129] Shape stability: Recovery rate after cyclic loading 91.8%, porosity 0.4%.
[0130] III. Conclusion: PEEK / silicon nitride composite materials have high wear resistance and reconfigurability through magnetic field-induced particle arrangement and gradient cooling, suitable for medical implant devices.
[0131] The experimental results of the embodiments are shown in the following figures:
[0132]
[0133] According to the above experiments, the application has the following effects:
[0134] 1. Significant improvement in mechanical properties:
[0135] The bending strength of Example One is 720 MPa, which is 50% higher than the prior art (480 MPa); the tensile strength of Example Three is 650 MPa, which is 50% higher than the untreated system (430 MPa).
[0136] 2. Enhanced shape stability:
[0137] The shape recovery rate of Example One after 5 cycles is 93.5%, with a decay amplitude of ≤2.5%, which is better than the prior art (85%, with a decay of 10%).
[0138] 3. Optimized interfacial bonding:
[0139] The interfacial shear strength of carbon fibers in Example One is 58 MPa (35 MPa in the prior art); the interfacial bonding energy of silicon nitride in Example Three is 1.8 J / m 2 (1.2 J / m 2 ) in the untreated system.
[0140] 4. Improved process efficiency:
[0141] The programmed cooling rate (2-8℃ / min) reduces residual stress by 40% and energy consumption by 30% compared to traditional quenching (10℃ / min).
[0142] 5. Multifunctional adaptability:
[0143] Example Two achieves ordered arrangement of particles through electric field assistance, suitable for electromagnetic sensitive devices; Example Three induces self-organized structure through magnetic field, extending to the field of biological medicine.
[0144] 6. Precise control of microstructure:
[0145] The porosity is ≤0.5% (1.2% in the prior art), and the uniformity of the reinforcing phase distribution (coefficient of variation ≤8%) supports high-precision applications.
[0146] Although embodiments of the application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the application, and the scope of the application is defined by the appended claims and their equivalents.
Claims
1. A composite material thermoforming method based on thermally activated topological reconstruction, characterized in that: The following steps are involved: S1. Material pretreatment: preparing a composite material blank comprising a heat-activated matrix and a reinforcement phase, and performing interface modification on the reinforcement phase; S2. Topological structure design: Pre-deform the blank above the glass transition temperature of the base material, form a temporary topological configuration through mold constraints, and then programmatically cool and lock the stress; S3, thermal activation stage: heating the programmed blank to an activation temperature range, wherein the temperature range is from the transition temperature to the transition temperature + 50 ° C, and applying an external field assistance; S4, dynamic reconstruction forming: guiding the dynamic rearrangement of the material molecular chains and the reinforcement phase under thermal activation to form the target topological structure; S5, topological locking: fix the reconstructed topological structure through gradient cooling or cross-linking curing; S6. Post-processing and verification: Machining and performance testing of formed parts.
2. A composite material thermoforming method based on thermally activated topological reconstruction according to claim 1, characterized in that: In S1, the heat-activated matrix is thermoplastic polyimide, shape memory epoxy resin or polyetheretherketone, the reinforcement phase is at least one of continuous carbon fiber, aramid fiber or silicon nitride particles, and the surface of the reinforcement phase is treated with a silane coupling agent or oxygen plasma.
3. The composite material thermoforming method based on thermally activated topological reconstruction according to claim 1, characterized in that: In S2, the programmed cooling rate is 2-8°C / min, and during the cooling process, the mold is kept to apply a constraint pressure of 0.5-5 MPa to the blank.
4. The composite material thermoforming method based on thermally activated topological reconstruction according to claim 1, characterized in that: In S3, the external assistance includes at least one of the following: Mechanical pressure: applied by air pressure or hydraulic pressure, with a pressure range of 0.5-8MPa; Electric field: field strength is 1-10kV / mm, frequency is 50Hz-1kHz; Magnetic field: The magnetic induction intensity is 0.1-2T.
5. The composite material thermoforming method based on thermally activated topological reconstruction according to claim 1, characterized in that: In S4, the strain rate of the dynamic reconstruction forming is controlled within the range of 5×10-3 to 5×10-2s-1, and the guidance method of the target topological structure includes: Mold cavity geometric constraints; Synergistic regulation of the preset gradient distribution of the reinforcement phase and the difference in thermal expansion coefficient; The direction of the external stress field matches the orientation of the reinforcement phase.
6. The composite material thermoforming method based on thermally activated topological reconstruction according to claim 1, characterized in that: In the step S5, the gradient cooling rate is 1-3°C / min, and the crosslinking curing is triggered by UV irradiation or thermal initiator, the UV irradiation wavelength is 300-400nm, and the irradiation dose is 20-80mJ / cm 2 .
7. The composite material thermoforming method based on thermally activated topological reconstruction according to claim 1, characterized in that: In the S6, the performance test includes: Microstructure analysis: Observe the distribution of the reinforcement phase and the interface bonding state by micro-CT or scanning electron microscopy (SEM); Mechanical properties test: determination of flexural strength, interlaminar shear strength and anisotropic modulus; Shape stability verification: Cycle loading 3-5 times in an environment of transition temperature ±10℃, and the shape recovery rate is ≥90%.
8. The composite material thermoforming method based on thermally activated topological reconstruction according to claim 1, characterized in that: Multiple topological structure reconstructions of the same blank are achieved by repeating S3-S5, and the shape recovery rate decays by ≤5% after each reconstruction.
9. The composite material thermoforming method based on thermally activated topological reconstruction according to claim 1, characterized in that: The composite material has a spatial gradient topological structure, the volume fraction of the local reinforcement phase thereof changes continuously within the range of 10%-60%, and presents a controllable anisotropic mechanical response under different temperature activation conditions.
10. The composite material thermoforming method based on thermally activated topological reconstruction according to claim 1, characterized in that: In S4, the material strain field distribution is monitored based on infrared thermal imaging or fiber optic sensors, and external field auxiliary parameters are dynamically adjusted to ensure that the forming accuracy error of the target topology structure is ≤1.5%.