59 results about "Volume content" patented technology

The invention discloses a polyimide composite material and a preparation method thereof, and relates to the technical field of functional composites.The polyimide composite material is composed of hollow quartz fibers and silicon-containing polyimide resin, the fiber volume content of the polyimide composite material is 45%-60%, and the density of the polyimide composite material is 1.25-1.55 g / cm < 2 >; wherein the silicon-containing polyimide resin is formed by polymerizing a mixture of aromatic dianhydride, aromatic diamine and diamine containing a siloxane structure, and an end-capping reagent. The preparation method comprises the following steps: synthesizing a polyamide acid solution, preparing a prepreg by preimpregnation, performing by a vacuum bag method, performing hot-pressing curing and performing high-temperature post-treatment. Through collaborative innovation of the components and the process, the preparation method is simple, and the composite material has ultralow density, ultrahigh heat resistance, low dielectric constant and high strength and is suitable for the fields of aerospace, 5G communication, semiconductors and the like.

The invention belongs to the technical field of building materials, and particularly relates to a geopolymer composite material and a preparation method and application thereof. The geopolymer composite material provided by the invention comprises a geopolymer matrix and fibers doped in the geopolymer matrix, the volume mixing amount of the fibers in the geopolymer composite material is 1.5-2%; the fibers comprise modified natural fibers and synthetic fibers, and the volume ratio of the modified natural fibers to the synthetic fibers is (0.5-1): (0.5-1); the preparation method of the modified natural fiber comprises the following steps: soaking natural fiber in a strong alkali solution, and modifying to obtain the modified natural fiber; the natural fibers comprise jute fibers and / or coconut fibers. According to the invention, the modified natural fiber and the synthetic fiber are compounded to form a mixed fiber reinforced system, so that the usage amount of the synthetic fiber is reduced; and by controlling the dosage ratio of the modified natural fibers to the synthetic fibers, the natural fibers play a role in skeleton reinforcement in the cracking stage, and the overall strength of the geopolymer composite material is improved.

The present application relates to the technical field of fireproof coating, and particularly relates to a geopolymer-based aerogel fireproof coating, a preparation method and application thereof. The fireproof coating comprises the following components in the following proportions: geopolymer precursor material, alkaline activator, aerogel, fiber and water; the mass ratio of the alkaline activator and the geopolymer precursor material is 0.52-0.63:1; the volume content of the aerogel is 70%-85%; the mass content of the fiber is 0-1% and is not 0; and the water-binder ratio is 0.5-0.7. The added fiber can effectively inhibit the high-temperature shrinkage of the coating, and at the same time, to a certain extent, improve the tensile strength and tensile bonding strength, so as to ensure the structural stability and continuous fireproofing capability of the coating in a fire scene; by optimizing the aerogel content and the water-binder ratio, the coating realizes an excellent balance between the thermal conductivity and the compressive strength, and has the characteristics of high strength and efficient heat insulation; the production process of the present application is low-carbon and environmentally friendly, and has economic and environmental benefits.

The invention relates to the technical field of high-temperature fire-resistant composite materials, and provides a high-density ablation-resistant rudder heat-proof cup and a manufacturing method thereof.The manufacturing method comprises the steps that 2.5 D quartz fabric is adopted for Z-direction sewing; the sewn fabric is put into a shape maintaining device, and the shape maintaining device adjusts the fiber state of the fabric and improves the fiber volume content to 50-65%; the fabric subjected to shape maintaining operation is firstly impregnated and shaped with inorganic sol and then impregnated and cured with a phenolic aldehyde solution, and a rudder heatproof cup blank is obtained; and finally, machining to obtain the rudder heat-proof cup. The density of the rudder heat-proof cup reaches 1.6 g / cm < 3 > or above, the linear ablation rate on a kerosene small engine is smaller than 0.1 mm / s, and the rudder heat-proof cup is excellent in ablation performance and suitable for thermal protection of a ballistic missile aerial rudder shaft.

The invention discloses an I-shaped mould pressing polymer workpiece and a preparation method thereof. The workpiece comprises a web, a first wing plate and a second wing plate, the first wing plate and the second wing plate are symmetrically parallel and are formed by compression molding of sheet molding compounds, pultrusion profiles are embedded in the web to enhance rigidity, and the parallelism of the wing plates is smaller than or equal to 0.5 mm. According to the preparation method, a pultrusion profile is coated with a material sheet of the sheet molding compound, then mold pressing is conducted, the mold pressing temperature is 120-140 DEG C, the pressure is 8-15 MPa, and the pressure maintaining time is calculated according to the thickness of a web. The formula of the sheet molding compound contains unsaturated polyester resin, epoxy vinyl ester resin and the like, and the glass fiber accounts for 30-40% of the total weight. The pultrusion profile is mainly made of unsaturated polyester resin, the fiber volume content is larger than or equal to 50%, and the surface is subjected to sand blasting or corona treatment. According to the workpiece prepared by the method, the bending strength is improved, the salt spray corrosion resistance is improved, the thermal deformation temperature is increased, and the problems of poor rigidity and low precision of a traditional sheet molding compound molded profile are solved.

The invention relates to a hybrid fiber composite material rib with ribs on the surface and a preparation method thereof, and belongs to a resin fiber material. The rib material comprises carbon fibers, other fibers and a resin matrix, the carbon fibers and the other fibers are embedded in the resin matrix, and spiral resin ribs are arranged on the surface of the rib material. The other fibers are selected from one or more of aramid fibers, basalt fibers and glass fibers. The carbon fibers are distributed at the core part of the rib material, and the other fibers are distributed at the periphery of the carbon fibers. The diameter of the rib material is 2mm-36mm, the volume content of the carbon fibers is 52%-57%, and the volume content of the other fibers is 19%-22%. The rib material has the excellent axial strength and elasticity modulus of the core layer carbon fiber and the additional performance of other fibers on the surface layer, the comprehensive performance and integrity of the rib material are improved, and the service requirements of more complex application scenes are met.

To provide a fiber-reinforced plastic capable of storing a matrix resin at a normal temperature, reducing management of a molding process while management of liquid preparation is unnecessary and further having an impact resistance.SOLUTION: A fiber base material in which a plurality of reinforcing fiber yarns are arranged in one direction and which has a high density of 50-65% fiber volume content calculated from thickness of a sheet at 0.1 Mpa pressure and is formed in a sheet shape is incorporated, and technical means is adopted in which the fiber base material or a laminate of the fiber base materials is impregnated with a one pack curable type thermoset acrylic resin and is incorporated by curing.SELECTED DRAWING: Figure 4

The invention belongs to the field of new materials, relates to the field of fiber preforms, and particularly provides a 2.5 D woven preform of a U-shaped radome, which adopts the 2.5 D woven preform with excellent interlayer strength as a composite radome reinforcement. The reinforcement body is prepared by integrally sewing the 2.5 D laminated woven main prefabricated body and the 2.5 D laminated sewn secondary prefabricated body through a three-dimensional sewing process, and has the characteristics of high fiber volume content, high surface precision and low manufacturing cost; the antenna housing 2.5 D braided preform / aryne composite material prepared from the material has the advantages of high interlayer strength, good dielectric property, outstanding high temperature resistance and the like, and is particularly suitable for the requirements of high-temperature, high-overload and near-net-size formed composite material wave-transparent antenna housing.

The invention discloses a preparation method and a preparation mold for a thin-wall ceramic matrix composite spray pipe, belongs to the technical field of preparation of ceramic matrix composite spray pipes, and solves the problems that the preparation process of an existing three-dimensional needling preform is complicated and is not suitable for a thin-wall spray pipe preform. Comprising the following steps: driving a mold to rotate by utilizing a cloth tape winding machine, and winding a preform on the mold; cracking the preform by adopting a vapor deposition process; depositing a pyrolytic carbon interface layer on the surface of the preform; performing high-temperature treatment on the prefabricated body; impregnating and curing the prefabricated body by adopting a precursor impregnating and cracking process; carrying out SIC matrix deposition on the preform by adopting a chemical vapor deposition process; and machining the inner and outer molded surfaces of the prefabricated body. According to the method, the carbon cloth prepreg tape winding forming mode is adopted, so that the preparation precision of the preform can be improved, fiber faults in the machining process are reduced, and the circumferential strength is enhanced. And meanwhile, the fiber volume content of the preform can be increased by a prepreg tape winding preparation process.

The invention belongs to the technical field of thermal field equipment, and discloses a guide cylinder for a thermal field and a manufacturing method of the guide cylinder. An integrated fiber prefabricated body is prepared on a mold, in the process, by controlling fiber layer laying, a barrel prefabricated part with the low fiber volume content, a ring prefabricated part with the high fiber volume content and a gradient transition area connecting the barrel prefabricated part and the ring prefabricated part are formed in the prefabricated body, and then a Z-direction reinforcing technology is adopted to enable the barrel prefabricated part, the ring prefabricated part and the gradient transition area to form a whole with continuous fibers; and carrying out densification treatment on the prefabricated body. By constructing an integrated structure with gradient performance, the guide cylinder body has excellent heat insulation performance, and the bottom ring piece has high mechanical strength. An anti-scouring functional layer with a reinforced bonding interface can be preferably arranged on the inner wall, and a bionic microscopic groove is machined, so that the structural reliability and the performance matching degree of the guide cylinder are cooperatively improved, and the service life of the guide cylinder is prolonged.

[Problem] A problem to be addressed by the present invention is to provide a CFRP with a low risk of edge glow by virtue of controlling the structure of the CFRP and without relying on expensive electroconductive particles. In other words, provided is a CFRP such that the risk of edge glow is greatly decreased, even in a case where electroconductive particles are used in an amount equal to or smaller than in a conventional technology. Further provided is a CFRP such that the risk of edge glow is greatly decreased without using electroconductive particles.[Solution] A carbon-fiber-reinforced composite material including carbon fiber sheets containing unidirectionally arranged carbon fibers, laminated multidirectionally one on another, and impregnated with a matrix resin, which is cured; wherein, assuming that a region in which the carbon fibers have the same angle of fiber orientation consecutively in the thickness direction is defined as a Layer, and that, when the Layer is composed of a plurality of regions having a given thickness, and having different carbon fiber volume content factors (Vcf), each of the regions having a given thickness is defined as a Sublayer, the carbon fiber sheet contains a specific Layer that satisfies (1) to (3), and the thickness of a resin portion between the specific Layer and at least one Layer adjacent to the specific Layer is 5 μm or less; (1) the average Vcf of the Layer (hereinafter referred to as the Layer average Vcf) is 50% or more, (2) as both outermost parts of the Layer, Sublayers each having a Vcf the ratio of which to the Layer average Vcf is 0.5 or more (hereinafter, such a Sublayer is referred to as a high-Vcf Sublayer) are disposed, wherein each average Vcf is higher than the Layer average Vcf, and (3) between the high-Vcf Sublayers as both outermost parts of the Layer, a Sublayer having a Vcf the ratio of which to the Layer average Vcf is less than 0.5 (hereinafter, such a Sublayer is referred to as a low-Vcf Sublayer) exists.

The invention provides a maritime work cement-based material floating structure protection layer and a preparation method thereof, and relates to an ocean engineering material. The maritime work cement-based material floating structure protection layer comprises a surface layer and a bottom layer, and a cementing material of the surface layer is composed of cement, mineral powder, nano SiO2 and calcium carbonate whiskers according to the mass ratio of 40: 43-47: 9-11: 4-6; basalt fibers are doped into the surface layer, and the volume mixing amount of the basalt fibers is controlled to be 1.5%-2.5%; the bottom layer is formed by mixing cement, silica fume, metakaolin, quartz sand powder and elastic latex powder according to the mass ratio of 60: (9-11): (9-11): (9-11): (9-11); and an iron gauze is embedded in the bottom layer. The thickness of the surface layer is 3-5 mm, and the thickness of the bottom layer is 3-5 mm. The maritime work cement-based material floating structure is better optimized through the protective layer, a more stable and durable floating platform for mariculture and the like can be provided, and the development requirements of deep and far sea ocean engineering are better met.

The invention discloses a method for detecting the content of mica in fine aggregate, and belongs to the technical field of concrete raw material detection. The method comprises the following steps: S1, preparing an SEM sample sheet: preparing an epoxy resin block embedded with fine aggregate, and carrying out mirror polishing treatment on the surface of the epoxy resin block to prepare the SEM sample sheet; step S2, image acquisition; s3, preliminarily screening mica particles; s4, secondary screening of mica particles; s5, screening the mica particles for the third time; s6, mica content calculation: calculating the volume content and the mass content of mica particles in the fine aggregate. SEM sample slices are prepared according to the steps of drying, screening, sample inlaying, mirror polishing and the like, and human errors are prevented from being introduced; the mica particles in the SEM sample slice image are identified and screened by adopting three modes, so that the comprehensiveness and the accuracy of the mica particle detection mode are improved, and the accuracy and the reliability of the mica content detection result are further improved.

A kind of continuous fiber wet winding process technology method and device of post large tension, it is characterized in that, including the following procedures: fiber yarn route design, fiber spread yarn thinning control, impregnation auxiliary adjustment, winding resin preparation, fiber impregnation adjustment, impregnated fiber spread yarn extrusion glue adjustment, winding tension adjustment, winding line design, solidification and mechanical property test.The device of the application is simple, can be popularized and applied, and low wear winding under large winding tension can be realized.The present application effectively solves the process problem that traditional process cannot simultaneously realize fiber low damage impregnation and fiber large tension precision winding by designing special winding device and matching winding process, and provides an efficient process technology path for realizing high fiber volume content and high mechanical property fiber composite material preparation.

The application discloses an integrated expansion section preform and a preparation method thereof. The preparation method comprises the following steps: making a forming die; dividing the preform into N unit layers with different areas according to function requirements; laying different kinds of unit layers on the forming die according to the function requirements of each part of the preform, and fixing the unit layers layer by layer by using a needle punching process; fixing and suturing the unit layers after being punched for several layers by using a blind seam process; and performing needle punching and blind seam on all the unit layers, so that each unit layer forms an entirety, the forming preform is taken out of the die, and the preparation of the preform is completed. The preparation method of the application is used for making the preform by layer stacking thickness, the fibers of the layer are continuous, the integrated expansion section is formed, the overall structural strength is improved, the interlaminar performance and comprehensive performance of the composite material are enhanced, the fiber volume content of the preform is improved, and the expansion section with complex structure, large curvature and various sizes can be prepared.

The application provides a kind of nano-modified ultra-high toughness concrete and its preparation method, provide a kind of nano-modified ultra-high toughness concrete, by mass fraction, including the following preparation raw materials: fine aggregate 100~140 parts, water 8~18 parts, water reducing agent 2~4 parts;Cementitious material: silica fume 10~20 parts, superfine fly ash silicate aluminate fine substance 10~30 parts, cement 50~80 parts;Wherein, water-binder ratio is 0.16;And steel fiber volume content 1.2~2.5%, the content of nano-silica is 0.5~2%.The application is limited by the composition of ternary cementitious system and the content of nano-silica;Obtain the working performance and mechanical properties of ultra-high toughness concrete that have been greatly improved;The nano-modified ultra-high toughness concrete preparation method of the application has the characteristics of low cost, convenient operation, wide application scene, suitable for industrial production.

The application relates to a cemented carbide with needle-shaped structure and a preparation method thereof, and belongs to the technical field of cemented carbide additive manufacturing. The method comprises the following steps: WC-VC-Co spherical composite powder is prepared by taking WC, Co and VC powder with an average particle size of less than 1 mu m as raw materials; after heat treatment and particle size grading, the WC-VC-Co spherical composite powder is printed and formed by adopting a powder laying type selective laser melting device, so that WC and VC form VWC2 phases in situ under the action of laser; and the cemented carbide part obtained by printing is heat treated at 1410-1480 DEG C and 5-6 MPa in an argon atmosphere for 50-80 min, so that the VWC2 phases are decomposed into WC and V4WC5, and the formed WC is caused to grow in orientation. The cemented carbide with needle-shaped structure prepared by the application has a dense microstructure, needle-shaped WC is uniformly distributed in different directions in space, and the volume content of the needle-shaped structure is high.

The application belongs to the technical field of sports equipment, and particularly relates to an anti-fatigue badminton racket rod based on three-dimensional woven composite material and a manufacturing method, which comprises a net frame, a racket rod and a handle connected in sequence, and the net frame, the racket rod and the handle are integrally formed into a continuous whole member by three-dimensional woven composite material; the three-dimensional woven composite material comprises a reinforcing body and a matrix, the reinforcing body is a carbon fiber three-dimensional woven preform, and the matrix is modified epoxy resin; the fiber volume content of the racket rod is 55%-65%, the application constructs a fiber space interlocking network through a four-way weaving structure, eliminates interlayer interfaces and splicing stress concentration in combination with an integrated forming process, and improves the anti-fatigue performance, anti-torsion stiffness and interlayer bonding strength of the racket rod; through optimization of the fiber volume content and a stepped curing process, the best balance of strength, formability and fatigue life is achieved, and the technical problems of easy delamination, poor anti-fatigue performance and low connection reliability of a traditional laminated material badminton racket rod are solved.

The invention provides a discrete entity unit-based long fiber composite material performance prediction method, and belongs to the field of composite material simulation calculation, and the method comprises the following steps of: firstly, collecting model parameters; then, based on a unit cell array and fiber relocation, establishing a microscopic representative volume element (RVE) model of the long fiber composite material, and predicting to obtain equivalent performance parameters of a prepreg sheet; and finally, establishing a microscopic RVE model by simulating random placement of prepreg sheets, and predicting equivalent macroscopic performance parameters of the long-fiber composite material in combination with the microscopic RVE model. According to the method, the macroscopic performance parameters of the long-fiber composite material with high fiber volume content can be obtained only by determining the parameters of the fiber and the resin matrix and carrying out finite element asymptotic damage analysis based on a sequential multi-scale method. Meanwhile, a standard hexahedron unit is adopted for the microcosmic RVE model, the number of node freedom degrees is reduced, and high-efficiency and high-precision macroscopic performance prediction of the long-fiber composite material can be achieved.

The application discloses a kind of elastic modulus prediction calculation methods under the multiscale of ultra-high performance concrete, the prediction calculation method includes (1) according to material composition and representative volume element (RVE) size, the structure type of determining solution object;(2) according to the structure type of solution object, RVE unit internal component is divided into matrix phase and inclusion phase;(3) according to the volume content of matrix phase, elastic parameter and the morphology of inclusion phase, elastic parameter, volume content, the local strain concentration tensor of all inclusion phase is calculated;(4) according to the local strain concentration tensor of all inclusion phase, the elastic parameter of RVE is calculated using mean field theory.Compared with conventional test methods such as empirical formula method, finite element calculation method, this method is not only more suitable for a variety of doped ultra-high performance concrete composite materials, but also can improve the calculation efficiency of concrete elastic parameters under different scales.

Provided is a concrete reinforcing composite material that is impregnated with a thermoplastic resin having excellent alkali resistance and handleability. In a concrete reinforcing composite material 10, a core material 12 is formed from a fiber bundle of reinforcing fibers. The core material 12 is covered with a coating layer 14 made of a thermoplastic resin. The core material 12 is impregnated with the thermoplastic resin. The thickness of the coating layer 14 is 84 μm or more. The fiber volume content Vf of the core material 12 is 60% or more.

The invention relates to a concrete comprising a binder (1), and wood particles (2) coated in a metakaolin (3), the volume content of the wood particles (2) in the concrete being greater than or equal to 30%. The invention also relates to a method for manufacturing a concrete according to the invention. This method is particular in that it comprises the following steps: - mixing the wood particles (2) with the metakaolin (3), in order to obtain a coating of the wood particles (2) by the metakaolin (3), - mixing the wood particles (2) with at least one binder (1) and water. Figure for abstract: Fig 1

The application discloses a kind of directional reinforced puncture fabric and its forming method, comprising: step 1: according to the design of fabric directional reinforcement requirement, unit layer includes at least one fiber layer, and the unit layer formed by at least one fiber layer is distributed with fiber in multiple directions, and the volume content ratio of fiber distributed in multiple directions is not all same;Step 2: the fiber layer in the first layer unit layer is sequentially laid in the puncture device and puncture pressurization setting is carried out;Step 3: the fiber layer of remaining unit layer is sequentially carried out puncture pressurization setting according to step 2 until reaching predetermined height;Step 4: the position of puncture needle is replaced by Z direction fiber bundle one by one, and finally three-dimensional fabric is formed.The application utilizes the fiber type, fiber structure, organization structure and fiber layer combination design of fiber layer, realizes the limit promotion of fabric specified single or multiple direction fiber volume content or performance, forms directional reinforced puncture fabric to meet the requirement of material directional high performance.

This invention discloses a method for distributed unidirectional fiber composite material damage testing and characterization. The method comprises the following steps: Step S1: selecting fibers and a matrix, determining the fiber volume content, and controlling the positional distribution of a single-mode sensing optical fiber within the unidirectional fiber composite material; then forming the fibers, matrix, and single-mode sensing optical fiber into a unidirectional fiber composite material; Step S2: employing millimeter-level high-spatial-resolution strain sensing technology to perform optical fiber high-spatial-resolution strain testing on the unidirectional fiber composite material, collecting optical fiber single-mode sensing optical fiber strain, and performing damage testing and characterization on the unidirectional fiber composite material. This method can be effectively applied to characterize and evaluate the entire process of damage initiation, development, and evolution in unidirectional fiber composite materials.

Method for producing a fiber composite component (10) containing recycled carbon fibers (2), in particular a fiber composite component (10) for a motor vehicle, comprising the steps: - Providing flat semi-finished fiber products (3) containing recycled carbon fibers (2), wherein the proportion of recycled carbon fibers (2) is at least 50 vol.%, based on the total volume of the fibers used in the semi-finished fiber product (3), - Production of a standard fibre composite component with a defined number of fibre semi-finished products (3), defined fibre material, defined matrix material and defined layer arrangement, - Determining the flexural rigidity of the fiber composite component (10) according to the following formula (1): B bv = φ ( t ) φ lit = E lit , where B bv (t) the flexural rigidity of the fiber composite component (10) to be produced, E bv the elastic modulus of the fiber composite component (10), t sollis the layer thickness of the fiber composite component (10) and v is the Poisson's ratio, where E bv is determined using the following formula (2): E bv = φ ( t ) φ lit E lit , where E lit the elastic modulus of the fiber composite standard component, φ lit is the fiber volume content of the fiber composite standard component and φ(t) is the fiber volume content in the fiber composite component (10), - Arranging a number of flat fiber semi-finished products (3) which have the desired bending stiffness B bv (t) results in - Impregnating the flat fiber semi-finished products (3) with matrix material (9) and - Hardening of the matrix material (9).

The invention provides a numerical analysis method for an all-carbon hybrid laminated plate based on continuum damage mechanics, which is characterized in that a constitutive model for describing LE and HE layers and a UMAT subprogram for damage evolution are written based on secondary development of finite element software, and material parameters are obtained by subsequently performing uniaxial tensile test on a pure LE fiber laminated plate and a pure HE laminated plate. Two centralized configurations with the same LE layer volume content and different LE layer thicknesses are prepared by utilizing a vacuum bag method, and damage evolution and stress-strain response of the centralized configurations are obtained by utilizing a digital image correlation technology. On the basis of continuous medium damage mechanics, progressive damage of an LE layer and local layering of an LE / HE interface are achieved in a finite element model, and the micro damage mechanism of the pseudo-ductility is revealed. According to the method, the defects of an existing numerical method are overcome through the simulation technology, the efficient, feasible and accurate method is provided for accurately predicting the full-carbon interlayer hybrid material, and experimental verification is carried out.

The present invention is a thermally conductive sheet comprising a plurality of unit layers, each comprising a silicone resin and a thermally conductive filler, the plurality of unit layers being laminated such that the plurality of unit layers are adhered to each other, wherein a volume content of the silicone resin is 32% by volume or less, and a compressive load at a sheet area of 25.4 mm×25.4 mm when the thermally conductive sheet is 30% compressed from a direction perpendicular to an adhesion plane on which the plurality of unit layers are adhered to each other is 7.0 kgf or less. According to the present invention, it is possible to improve the thermal conductivity and enhance the softness of a thermally conductive sheet using a silicone resin as a matrix component and composed of a large number of unit layers laminated as compared with the conventional one.

The application discloses a kind of temperature response type double-layer interlocking fabric and preparation method thereof, including surface layer, inner layer and interlocking yarn, surface layer and inner layer form interlocking by interlocking yarn, inner layer is formed by inner layer warp yarn and inner layer weft yarn interweave, inner layer warp yarn and inner layer weft yarn all include core line and ornament line, fabric has first state, second state and third state, the length and diameter of interlocking yarn in first state are all greater than the length and diameter in second state;The length and diameter of core line in first state are all less than the length and diameter in second state, the length and diameter of core line in third state are all greater than the length and diameter in second state;The length and diameter of ornament line in third state are all less than the length and diameter in second state.The double-layer interlocking fabric of the application can adjust air layer volume content in fabric with temperature change, to realize the function of storing and releasing heat, can form stable and comfortable temperature for people in the closed space of fabric contact skin.

The invention relates to a method for repairing a part (10) made of a ceramic matrix composite material, the part having a damaged zone, the method comprising: - a step of machining away at least the damaged zone so as to obtain a recessed repair zone (12); - a step of placing, in the recessed repair zone (12), a repair material (13) comprising at least one ply (15) of composite material preimpregnated with a ceramic matrix precursor; - a step of compacting the one or more plies (15) of composite material preimpregnated with the ceramic matrix precursor in order to increase a fiber volume content; and - a sintering step for consolidating a bond between the repair material (13) and the composite part (10).

The invention provides a method and a system for predicting the static water external pressure bearing capacity of a composite material flexible pipe, and relates to the technical field of ocean engineering, the method comprises the following steps: calculating the structural instability pressure of a pipeline under the static water external pressure and the material failure pressure obtained by iteration based on a Hashin-Yeh failure criterion in parallel, and taking the smaller value of the two as a final bearing capacity prediction value. Wherein the thick lining layer and the outer protection layer are theoretically divided into sub-layers with the same thickness as the enhancement layer, so that the improved laminated plate theory can be applied to accurately calculate the instability pressure; meanwhile, a formula based on fiber and matrix performance and fiber volume content is adopted to calculate a material elastic constant, and a Hashin-Yeh criterion capable of distinguishing multiple failure modes is utilized to carry out iterative failure judgment, so that an empirical damage coefficient is abandoned. According to the method, the accuracy and reliability of still water external pressure bearing capacity prediction of the deep sea composite material flexible pipe are remarkably improved, and a scientific basis is provided for pipeline safety design and optimization.