2348 results about "Fibrous composites" patented technology

The invention discloses a mechanical property prediction method of a composite material based on an improved sparrow algorithm-random forest, and belongs to the technical field of composite material property prediction, and the method comprises the following steps: carrying out finite element multi-scale simulation on a carbon fiber composite material to obtain an elastic constant matrix; connecting the elastic constant matrix material to a macroscopic model for macroscopic simulation to obtain sample data; a random forest RF model is constructed in Matlab software; an improved sparrow search algorithm is introduced into a random forest RF model to construct a CFSSA-SF prediction model; training a CFSSA-SF prediction model by using the training set data; and inputting test set data into the CFSSA-SF prediction model to obtain a prediction result. According to the method, the finite element method is adopted to carry out multi-scale modeling, the improved sparrow algorithm is combined with the random forest to construct the fusion CFSSA-RF prediction model, and the mechanical properties of the carbon fiber composite material under different parameters are effectively predicted.

The invention belongs to the technical field of fiber reinforced composite material additive manufacturing, and discloses a continuous fiber composite material 3D printer tail end heating extrusion device. Aiming at the problems of poor fiber impregnation degree of a resin matrix, low process flexibility of a mode of directly printing pre-impregnated composite filaments and incapability of changing the fiber content in a composite material structure by adjusting process parameters in real time in an in-situ impregnation printing mode, the invention designs an in-situ impregnation printing method capable of ensuring the printing process flexibility and improving the printing efficiency. According to the tail end heating extrusion device, the continuous fiber reinforced composite material structure can be formed in a high-quality mode, the fiber impregnation degree can be remarkably improved, and the structure of a printing nozzle is optimally designed. Through the structural design of the internal channel and the outlet nozzle of the tail end heating device, the impregnation effect of a resin matrix on continuous fibers can be improved, scraping of the nozzle on the continuous fibers is relieved, and the quality of a printing component can be effectively improved.

The invention discloses a processing control method and system for a carbon fiber composite transmission shaft, and relates to the technical field of intelligent transmission shaft manufacturing, and the method comprises the steps: dynamically adjusting the control current of a magneto-rheological damper through a PID controller based on a process control parameter set, and recording tension fluctuation and temperature gradient data; inputting tension fluctuation and temperature gradient data into an ANSYS coupling simulation engine, establishing a three-dimensional temperature field model, calculating a resin flow compensation coefficient, generating a temperature-pressure cooperative control curve through an NSGA-III multi-objective optimization algorithm based on the resin flow compensation coefficient, and calculating the resin flow compensation coefficient and the temperature-pressure cooperative control curve according to the resin flow compensation coefficient and the temperature-pressure cooperative control curve. And integrating through a time sequence control engine to generate a solidification control instruction. According to the invention, a multi-source data fusion algorithm is combined with the industrial Internet of Things edge computing gateway, so that accurate monitoring and synchronous processing of the process control parameter set are realized, and the dynamic behavior of the carbon fiber composite material in the processing process is comprehensively reflected.

The invention discloses a carbon fiber composite material surface modification spraying system and a control method thereof. The system comprises a multi-axis robot, a plasma spray gun, a contact angle measuring probe, a 3D line laser scanner, a hyperspectral imager, an environment sensor and a controller. According to the method, the plasma power and the robot speed are adjusted in real time through contact angle measurement and plasma treatment feedback control, so that the CFRP surface can accurately reach a target value, and the coating adhesive force is improved; 3D line laser scanning and hyperspectral imaging are combined, and the posture, the distance, the wet film thickness and the component uniformity of the spray gun are monitored in real time; based on a prediction model fusing a physical model and a neural network, a self-adaptive fuzzy PID control algorithm is adopted, and the coating flow and the track posture of a spray gun are accurately regulated and controlled in real time. The problems of weak coating binding force, uneven thickness, orange peel, sagging and serious coating waste in traditional spraying are effectively solved, and self-adaptive, high-quality and green spraying of workpieces with complex curved surfaces is achieved.

A composite material having a skin optionally including a top surface coating; and one or more layers. The skin is adapted to be used on or to produce sporting equipment, such as on a sport or game paddle. The present teachings also include a paddle having a core, a first skin, and a second skin, where the first skin and the second skin sandwich the core. The skins may be a multi-layer fibrous composite.

The invention relates to the technical field of special papermaking and carbon fiber composite material preparation, in particular to high-air-permeability pitch-based carbon fiber base paper and a preparation technology thereof.The preparation method comprises the following steps that 1, pitch-based carbon fibers A are cleaned with diluted hydrochloric acid; dividing and brooming aramid fibers to obtain aramid pulp B; 2, performing wet forming on the pitch-based carbon fibers and the aramid pulp to obtain carbon fiber paper; and step 3, impregnating the pitch-based carbon fiber paper with phenolic resin, drying, and finishing to obtain the pitch-based carbon fiber base paper. The invention provides a novel method for preparing the high-air-permeability carbon fiber base paper through acid cleaning of carbon fibers, fibrillation of aramid fibers, wet forming of mixed pulp, resin impregnation strengthening and hot-pressing finishing, and the method comprises the steps that aramid pulp assists in interweaving, low-concentration resin strengthening is conducted, and the high-air-permeability carbon fiber base paper is obtained; the problem that strength, flexibility, high conductivity and high air permeability are difficult to consider at the same time is solved, and the high-air-permeability carbon fiber base paper and the preparation process thereof are provided.

The invention belongs to the field of electric heating materials, and discloses an electric heating element and electrode integrated material based on a fiber woven structure, an electric heating composite material and a preparation method thereof. An electric heating element and an electrode in the material are made of integrated fiber woven fabric. The electrode area is composed of a high-conductivity carbon fiber woven structure, and the high-conductivity characteristic of the electrode area is obtained through in-situ growth of graphene on the fiber surface through chemical vapor deposition; the electric heating area is composed of fiber cloth with a certain conductive characteristic. According to the fiber electric heating / electrode integrated woven structure, an extra electrode is prevented from being used in an electric heating material structure, and the problems of combination and connection of the electrode and the electric heating material and the defect of poor contact are solved. Meanwhile, the electric heating / electrode fiber integrated woven structure retains the integrity of a fiber electric heating element / electrode fabric, solves the problem of mismatching of material modulus, thermal expansion coefficient and the like caused by the use of a metal electrode, and can be applied to the fields of electric heating resin-based fiber composite materials, electric heating ice prevention and removal and the like.

The invention discloses a modified aramid fiber as well as a preparation method and application thereof. The modified aramid fiber comprises an aramid fiber and a carbon nanotube, the aramid fiber and the carbon nanotube are connected through an amido bond, the length of the carbon nanotube is 1-5 [mu] m, and the surface of the carbon nanotube is grafted with an amino-containing polymer. According to the modified aramid fiber disclosed by the invention, the surface roughness of the aramid fiber is improved due to the fact that the carbon nanotubes with the length of 1-5 microns are grafted on the surface, so that the aramid fiber and the epoxy resin generate a mechanical locking effect. Furthermore, the amino groups on the surface of the modified aramid fiber are covalently bonded with the epoxy resin, so that the bonding force between the fiber and the resin is further improved. In addition, the modulus of the introduced interface layer is between the modulus of the resin and the modulus of the aramid fiber, so that the defects at the interface of the fiber composite material under working conditions can be reduced. Meanwhile, the modified aramid fiber can be continuously produced, the treatment process is simple, efficient and green, and industrial amplification is facilitated.

The invention discloses a carbon fiber composite material layer extrusion device and method, and relates to the technical field of carbon fiber composite material processing.The carbon fiber composite material layer extrusion device comprises a working frame, a movable through groove and an extrusion mechanism are formed in the bottom end of the working frame, the extrusion mechanism comprises a fixing frame rod, a rubber sleeve and an extrusion roller, and the extrusion roller is arranged in the movable through groove; a fixing frame rod is arranged at the upper end of the extrusion roller, the bottom ends of the two sides of the fixing frame rod are connected with the two ends of the extrusion roller through bearings, the extrusion roller is sleeved with a rubber sleeve and a follow-up detection mechanism, the follow-up detection mechanism comprises an elastic ejector rod and an extrusion rod, and the extrusion rod is installed in the middle of the rear side of the fixing frame rod through a rebound hinge. An elastic ejector rod is movably mounted on the front side of the top end of the extrusion rod. When a carbon fiber composite material continues to be twisted, laid and extruded, extrusion forming machining can be carried out, the flatness of an extruded area can be detected, and the comprehensiveness in the machining process is improved.

The invention provides a rapid repairing method for an aerospace carbon fiber composite material, and belongs to the technical field of carbon fiber composite material repairing, in the aspect of cleaning, a special cleaning agent for self-research is free of damage and efficient, a preset cleanliness can be achieved by matching with a tool with a replaceable brush head, a foundation is laid for repairing, the damage is accurately measured by advanced detection equipment, the detection precision is 0.1 mm, and the detection efficiency is high. The repair material is scientific in formula and reasonable in component proportion, it can be guaranteed that the performance of a repaired part is close to that of an original part, the strict repair technology such as vacuum auxiliary pressure injection and autoclave curing guarantees sufficient curing and optimal performance of the material, and it is guaranteed that the quality reaches the standard through surface treatment and detection; all the devices of the equipment cooperate and are provided with intelligent systems, parameters can be regulated and controlled, the technology can be automatically adjusted, the structure meets special aviation requirements, carrying and operation are convenient, various scene requirements are met, and the equipment has great significance in guaranteeing aircraft operation and flight safety.

The invention relates to the technical field of composite material lightning protection, in particular to a pyrolytic dynamics simulation analysis method for lightning stroke damage of a carbon fiber composite material. According to the technical scheme, the method comprises the following steps that a new model is established in ABAQUS / CAE, a carbon fiber composite material is established, a laminated plate laying layer is defined, a multi-physical field analysis step is set, load current density is applied to a lightning stroke action area, the pyrolysis behavior of the carbon fiber composite material under lightning stroke high Joule heat is simulated based on a pyrolysis kinetic model, and operation is established in a Job module. And parallel computing parameters are selected and submitted for solution, temperature field distribution is checked, and the current density diffusion trend is verified. Through the electric-thermal-structure coupling model, the conductivity gradient design and the lightning arc model, refined prediction of CFRP lightning stroke damage is achieved, the damage area is reduced, the lightning stroke process is accurately simulated, and the adaptation and protection effects on the lightning stroke environment are improved.

The invention discloses a carbon fiber composite material sound barrier forming device, and relates to the technical field of sound barrier forming, the carbon fiber composite material sound barrier forming device comprises a working bottom table and a first supporting column, the first supporting column is fixedly connected to the top surface of the working bottom table, an upper mold is installed on the lower surface of the top end of the first supporting column, a sound insulation barrier is arranged on the working bottom table, and an auxiliary assembly is arranged on the working bottom table; production and forming of the carbon fiber composite material sound barrier are divided into simultaneous operation of four stations with coherent processes, the four stations do not interfere with one another during operation, and the problems that in the traditional hot press forming process, equipment is in an idle state during cooling, demolding and other steps, four stations are adopted for simultaneous operation, and when one station is used for cooling and demolding, the equipment is not in an idle state are solved. Other stations can be used for machining, residue removal or release agent spraying, feeding and other operations, the equipment utilization rate is greatly improved, no obvious intermittency exists in the production process, and therefore more carbon fiber composite material sound barriers can be produced in unit time.

The invention relates to the technical field of composite material thermocuring molding, in particular to a carbon fiber composite material molding optimization control system, which is characterized in that historical molding data of a carbon fiber composite material is acquired through a historical data acquisition unit, and current state information of a carbon fiber mold is acquired through a mold state acquisition unit. The process parameter determination unit generates process parameters based on the A-PPO model and the current state information. And the image acquisition unit applies the process parameters to the mold to acquire a carbon fiber composite material image. And the image detection unit extracts the image features of the carbon fiber composite material by using a ResNet model, and evaluates the quality of a finished product in combination with a random forest model. And the process parameter optimization unit dynamically adjusts process parameters through an A-PPO model according to a finished product quality result. And the parameter determination unit further optimizes the process parameters by using Bayesian optimization to obtain optimized process parameter settings. The finished product quality and the production efficiency of the carbon fiber composite material are effectively improved.

The invention relates to the technical field of degradable fibers, and discloses a degradable bamboo fiber composite material master batch and a preparation method thereof. The composite material is prepared from the following raw materials: modified bamboo fibers, modified polylactic acid, polyadipic acid / butylene terephthalate, a lubricant, an antioxidant and a plasticizer. The preparation method comprises the following steps: 1) performing alkali treatment and tannic acid-metal ion compound modification on the bamboo fibers to form a hydrophobic surface; 2) blending and modifying polylactic acid and bio-based elastomer polyhydroxybutyrate to construct a tough matrix; and 3) carrying out melt blending on the modified bamboo fiber, poly (adipic acid) / butylene terephthalate, the modified polylactic acid and an auxiliary agent, and then carrying out extrusion granulation. The degradable bamboo fiber composite material master batch prepared by the invention has good processability and mechanical properties, and can be widely applied to the fields of disposable tableware, packaging materials, agricultural plastic mulching films and the like.

The invention relates to a basalt high-performance fiber composite material and a manufacturing method thereof.The composite material is obtained by treating, cooling and curing basalt fibers, specifically, the basalt fibers are grafted with boron nitride and multi-walled carbon nanotubes and then treated with a resin material, and then various properties of the fibers are improved; the fiber composite material is prepared from the following components in parts by weight: 5-10 parts of basalt fiber, 77-94 parts of boron nitride, 68-75 parts of multiwalled carbon nanotubes and 87-105 parts of maleic anhydride polybutadiene resin. According to the manufacturing method of the basalt high-performance fiber composite material, the basalt fiber composite material manufactured by the method is excellent in tensile property, impact resistance, wear resistance and the like.

The invention provides a composite material additive manufacturing method and device based on size error compensation, and the method comprises the steps: selecting the number, type and combination mode of materials needed by each layered structure strip according to the material performance of a prepared component and the local thermodynamic performance and mechanical performance of the component; all strips of the single layered structure are laid at the same time or in each round, so that the single layered structure is formed; each strip is made of a single type of material or is formed by laminating and compounding a plurality of single type of materials, and the self-adaptive laying method is executed according to data of various sensors in the laying process and data of a detection mechanism after laying; and the steps are repeated, and the strips are laid layer by layer according to the layer sequence of the layered structure till the component is formed. According to the method, through effective combination of additive manufacturing modes of multiple fiber composite materials, multiple materials are combined and then laid, and it is ensured that the distribution of fibers and the infiltration effect of a matrix reach the ideal state.

The invention discloses a carbon fiber composite material as well as a preparation method and application thereof. Based on the structural design of the liquid crystal polymer with different dimensions, a liquid crystal polymer molecule assembly layer is constructed on the surface of the carbon fiber, the roughness and surface activity of the surface of the carbon fiber are improved, and meanwhile, the interface performance of the composite material is improved through the efficient redirectionality of the liquid crystal polymer under the microcosmic mesocrystal domain structure and the load. Besides, based on the high orientation of the liquid crystal polymer in the interface phase of the composite material, a multi-dimensional heat conduction network is constructed, the dominant vibration mode of the carbon fiber and the resin matrix in the phonon heat transfer process is effectively coupled, the possibility of carrier phonon scattering at the interface is reduced, the interface thermal resistance is greatly reduced, and the thermal conductivity of the composite material is improved. Therefore, the heat-conducting property of the composite material is improved.

The invention provides a composite material skin isogeometric modeling method considering micro-pores, which comprises the following steps: obtaining internal characteristics of a composite material skin through an SEM scanning electron microscope, and establishing parameterized unit cell microstructure units according to the characteristics; determining a skin deformation area, constructing a constitutive matrix based on different components in the composite material, obtaining and endowing defined material attributes, and obtaining different unit mass matrixes and local stiffness matrixes in the area; and filling into the macroscopic overall matrix through an isogeometric mapping strategy, carrying out inverse mapping fitting on a skin appearance structure, and carrying out applied load calculation. According to the method provided by the invention, through an isogeometric analysis method, three-dimensional curved surface dimension reduction processing is realized, and the calculation cost is reduced; meanwhile, a parameterized microscopic unit is considered to ensure the accuracy of modeling; and the mechanical property of the composite material skin is really simulated. The method is suitable for the structure elasticoplastic deformation state that the skin bears large load, large deformation and the like, and calculation operation is easy and convenient.

The invention discloses a recyclable epoxy resin matrix and a preparation method thereof, and a composite material and a preparation method thereof, and relates to the technical field of composite materials. The recoverable epoxy resin matrix comprises mixed resin, a transesterification catalyst and a curing agent, the mixed resin comprises epoxy resin and thermoplastic toughening resin, and the mass of the thermoplastic toughening resin is 8-15% of the total mass of the mixed resin; the mass of the ester exchange catalyst is 3-7% of the total mass of the mixed resin; the mass ratio of the epoxy resin to the curing agent is 100: (30-70). The epoxy resin matrix disclosed by the invention has the advantages of high strength and good toughness, and the cured resin matrix can be degraded in an organic solvent, so that recycling of carbon fibers in the carbon fiber composite material is realized, and environmental pollution is reduced while the economic value of the carbon fiber composite material is greatly improved.

The invention relates to the technical field of plastic material preparation, and discloses a modified bamboo fiber, a PBAT composite material and a plastic object. The modified bamboo fiber comprises bamboo fiber subjected to hot pressing treatment in water and a closed aziridine cross-linking agent loaded on the bamboo fiber, and the mass ratio of the bamboo fiber subjected to hot pressing treatment in water to the closed aziridine cross-linking agent is 100: (1-10). The PBAT composite material comprises the following components in parts by weight: PBAT and modified bamboo fibers, and the mass ratio of the PBAT to the modified bamboo fibers is 100: (20-40). The modified bamboo fiber is subjected to hot pressing treatment in water, so that the generation of volatile gas caused by high-temperature processing can be avoided when the modified bamboo fiber is applied to the plastic material, and the interface interaction with the plastic material can be improved; the closed aziridine cross-linking agent can release active groups at high temperature, and can react with active functional groups such as hydroxyl and carboxyl on the surfaces of the bamboo fibers and the surfaces of the plastic materials, so that the interface interaction between the bamboo fibers and the plastic matrix is improved, and the tensile strength of the composite material is improved.

The invention provides a method and a system for predicting residual compression strength of a carbon fiber composite material after lightning stroke, and belongs to the technical field of electric digital data processing. According to the method, by considering the pyrolysis degree of the lightning stroke CFRP composite material, the non-linear mechanical property parameters related to the pyrolysis degree actually measured based on the test and the thermal and mechanical damage results predicted based on the electric-thermal-mechanical multi-physics field coupling model are calculated; an actually measured nonlinear mechanical property thermal damage factor and a mechanical damage factor caused by impact damage are introduced into a constitutive relation of the CFRP composite material, and a finite element simulation method capable of quantitatively predicting the residual compression strength after lightning stroke is established by virtue of finite element software ABAQUS; the problems that in the prior art, the influence mechanism of lightning stroke damage on the mechanical property of the CFRP composite material is not clear, and a simulation modeling method capable of being directly used for calculating and predicting the residual compression strength after lightning stroke is lacked are solved.

The invention belongs to an equivalent modeling method, and provides a foam core material composite material structure equivalent modeling method and a related device aiming at the technical problems that according to an existing foam sandwich composite material structure design method, time and labor are consumed in the calculation iteration process, and especially for a geometrically irregular special-shaped structure, related research is lacked. The method comprises the following steps: according to an enveloping appearance curved surface, endowing a fiber composite material with layer attributes and thickness, firstly, carrying out preliminary proofing design according to the enveloping appearance curved surface, selecting an appearance curved surface of a foam core material in a modeling process, endowing the foam core material with the attributes with equivalent thickness, and carrying out modeling; then, the optimized fiber composite material laying layer and foam core material attribute design result is determined through iterative optimization, under the condition that the design requirement is met through optimization, the fiber composite material is endowed with a face body attribute, the foam core material is endowed with an entity attribute, and the attributes of the fiber composite material and the foam core material are confirmed through strength checking; and an equivalent modeling result is ensured to meet a final requirement.

The invention discloses an aviation composite material-oriented ultrasonic guided wave damage rapid imaging method, which relates to the field of nondestructive testing, and comprises the following steps: calculating a frequency dispersion curve according to material parameters of a carbon fiber composite material plate, and obtaining an ultrasonic optimal excitation angle and an ultrasonic guided wave propagation mode; scanning and collecting two groups of ultrasonic guided wave signals in the orthogonal direction in sequence; decomposing the guided wave signal, and obtaining a reconstructed ultrasonic guided wave signal after extracting a target component according to the size of an energy entropy value; calculating time-frequency information and energy of the signal, and estimating the damage probability in the scanning path by combining a damage index; embedding the expansion kernel convolution and the double probability distribution function into the damage index curve to respectively realize the reinforcement of the damage index and the sharpening of the edge; and expanding the two groups of damage index curves in the orthogonal direction into a two-dimensional damage matrix, and imaging according to a composite path cross imaging method, thereby finally realizing damage positioning imaging of the carbon fiber composite material plate.

The invention relates to a fiber composite material uniform compaction device and a compaction method. The compaction device comprises a sealing gasket, a lower mold plate, a heating and cooling channel, an upper mold plate, a metal film, an oil pump, a base and the like, forming surfaces are arranged on the two opposite surfaces of the lower mold plate and the upper mold plate, and fiber prepreg is laid on the forming surfaces; the metal film is located on the lower side of the upper die plate, a metal bag cavity is formed between the metal film and the upper die plate, and the oil pump is connected with the metal bag cavity and fills oil into the metal bag cavity to generate forming pressure. The lower die plate is fixed to the base, and heating and cooling channels are arranged in the upper die plate and the lower die plate. The interior of the metal bag cavity is pressurized through the oil pump, uniform pressure is applied to all the surfaces of the fiber prepreg through expansion of the metal bag cavity, and therefore the problems that a traditional hard mold cannot apply uniform pressure to the curved surface and a soft mold cannot be attached to a blank in the whole process, so that a fiber composite material is not compacted sufficiently are solved.

The invention discloses a warping prediction optimization method for a complex carbon fiber composite suspension structure, and the method comprises the steps: S1, reading CAD and laying layers, and tracking a main heat flow along fibers to segment an anisotropic block; s2, rearranging nodes, locally fitting a principal curvature and a control area, extracting characteristics of a fiber angle, a layer thickness, a temperature and warping, and constructing a weighted adjacency graph; s3, retrieving a historical high-fidelity sample, mapping and enhancing the historical high-fidelity sample into a source domain graph, and performing confrontation training by combining an encoder and a domain discriminator to realize node-level alignment; s4, constructing a generator and a discriminator based on the alignment graph, and carrying out alternate confrontation optimization after preheating; s5, constructing reconstruction, confrontation, peak stress and energy constraint multi-target loss; and S6, the freezing generator reasones initial version warping, and evaluates a node risk clustering high-risk sub-domain. According to the method, on the premise that node-level physical conservation is guaranteed, the warping morphology of the carbon fiber composite component with any shape and fiber laying layer combination under the curing working condition can be rapidly and accurately predicted.

A mold (14) for producing fiber-reinforced composite components is described, comprising a frame (17) and / or a holding frame formed from at least one side retaining element (4) and a mold insert (9) having a forming contour (10). The mold insert (9) is formed from stacked layers of plate-shaped support elements (8). The mold insert (9) can be covered with a mold layer (15), and the fiber-reinforced composite material can be placed on the mold layer (15). The resulting fiber-reinforced composite component can then be molded with the forming contour (10) of the mold insert (9).

The invention provides a fatigue test method, system and equipment based on texture change of carbon fibers and a medium, and belongs to the technical field of material tests.The method comprises the steps that a carbon fiber composite material is selected as a test sample; applying a fatigue load to the test sample according to a designed test condition, and collecting a surface image of the test sample; the method comprises the following steps of: preprocessing an acquired image, clustering according to the gray level and texture similarity of pixels to obtain a plurality of clustering subareas, and marking different clustering areas by using different colors to complete color mapping; extracting texture feature parameters from the image after color mapping, and performing PCA dimension reduction to obtain key texture feature parameters; and comparing the key texture feature parameters of the image under different test conditions, identifying texture feature changes, and completing fatigue performance evaluation. According to the method, image processing and texture feature analysis are combined, so that non-destructive testing of the CFRP fatigue performance is realized, and the testing accuracy and efficiency are improved.

The present invention provides a long-short carbon nanotube reinforced and toughened fiber composite material and a preparation method thereof. The preparation method provided by the present invention comprises: a) mixing short carbon nanotubes, a thermosetting resin and an additive to obtain a resin-based slurry; b) pouring the resin-based slurry into a fiber preform and curing and forming it to obtain a long-short carbon nanotube reinforced and toughened fiber composite material; wherein: the fiber preform comprises: an upper fiber cloth layer, a long carbon nanotube fiber yarn layer, and a lower fiber cloth layer stacked and contacted in sequence; the long carbon nanotube fiber yarn layer is a yarn-like structure formed by long carbon nanotubes; the length of the short carbon nanotubes is 0.5 to 3 μm, and the average length is ≤2 μm; the length of the long carbon nanotubes is 50 to 1000 μm, and the average length is >100 μm. The present invention optimizes the spatial layout of long and short carbon nanotubes in the composite material, simultaneously achieving the dual purposes of intra-layer reinforcement and inter-layer toughening of the fiber composite material.

The invention discloses a recoverable benzoxazine / fiber composite material and a preparation method thereof, and belongs to the technical field of composite materials. The composite material is obtained by hot-pressing and curing degradable benzoxazine containing boric acid ester and fibers according to the mass ratio of 1: (0.1-0.8), the degradable benzoxazine containing the boric acid ester is obtained by reacting diphenol containing a boric acid ester structure, long-chain monoamine and paraformaldehyde according to a molar ratio of 1: 2: (4.1-4.4). The composite material prepared by the invention is obtained by hot-pressing and curing the degradable benzoxazine containing boric acid ester and the fiber, and the reversible boric acid ester bond endows the benzoxazine with excellent degradability and endows the composite material with excellent recoverability, so that the fiber can be reused. In addition, the composite material contains boron element, so that the composite material has excellent flame retardant property. The prepared composite material has wide application prospects in the fields of buildings, traffic, military industry and the like.

The invention discloses a halogen-free flame-retardant benzoxazine-epoxy / aramid fiber composite material and a preparation method thereof, and belongs to the technical field of polymer composite materials. The composite material is obtained by heating and curing main chain type phosphorus-containing benzoxazine, epoxy resin and aramid fiber according to the mass fraction ratio of (1%-50%): (40%-70%): (30%-70%); the main chain type phosphorus-containing benzoxazine is prepared by carrying out Mannich condensation reaction on phosphorus-containing diamine, bisphenol and paraformaldehyde according to the molar ratio of 1: 1: (4.1-4.4). According to the prepared composite material, main chain type phosphorus-containing benzoxazine modified epoxy resin serves as a matrix, the matrix and aramid fibers are subjected to heating curing to prepare the composite material, benzoxazine is crosslinked with the aramid fibers and the epoxy resin when subjected to ring opening polymerization, the interface bonding performance between the aramid fibers and the epoxy resin can be remarkably improved, and the composite material can be used for preparing the aramid fibers and the epoxy resin. The mechanical property of the composite material can be effectively improved; meanwhile, benzoxazine contains phosphorus, so that the flame retardant property of the composite material can be improved, and the application field of the aramid fiber composite material is expanded.