254 results about "Interlaminar shear" patented technology

The invention relates to the technical field of preparation of high-performance composite materials, and discloses a multilayer fabric laying method for improving interlayer bonding strength of a carbon fiber material, which comprises the following steps: step 1, selecting carbon nanotubes or graphene sheets as nanoparticles, carrying out chemical oxidation treatment to introduce functional groups, and carrying out functionalization treatment by using a silane coupling agent; step 2, mixing the functionalized nano particles with epoxy resin in a high-shear-force mixing device to form uniform nano reinforced resin; and 3, weaving the carbon fibers according to a predetermined three-dimensional structure mode by using a three-dimensional weaving machine, and monitoring the fiber tension and the weaving density in real time in the weaving process. By using nanoparticles to reinforce the composite material and carrying out chemical oxidation and coupling agent functionalization treatment, the interface adhesive force between the carbon fibers and the epoxy resin is improved, functional groups can form stronger chemical bonds with the resin, the interlaminar shear strength of the composite material is improved, and the overall structural integrity and durability of the material are enhanced.

A preparation method of an emulsion type aramid fiber sizing agent belongs to the technical field of fiber surface treatment, and the specific scheme is as follows: preparing aromatic polyamide from corresponding diamine and acyl chloride, then reacting with epoxy resin to prepare modified epoxy resin, and preparing the emulsion type aramid fiber sizing agent under the action of a compound emulsifier. The preparation method disclosed by the invention is simple and relatively low in cost, better interface bonding can be formed between the aramid fiber and the epoxy resin after sizing by the sizing agent, and particularly, the interlayer shear strength of the aramid fiber / epoxy resin composite material is relatively well improved; the preparation method has important significance in improving the use performance and stability of the aramid fiber composite material and expanding the application of the aramid fiber.

Carbon composites, including carbon fibers, are disclosed and exhibit unique, advantageous mechanical properties, including inter laminar shear strength, compression strength, and resistance to forces applied at angles deviating from parallel to the longitudinal axis of the overall fiber. These improvements allow use of less material while conveying improved strength in myriad practical applications, reducing overall financial cost of fabrication, distribution, and practical utilization of resulting products. These advantages are optimized via utilizing inventive fabrication techniques that incorporate carbon filaments into carbon fibers, preferably incorporating carbon filaments including three-dimensional (3D) graphene platelets into said fibers. The filaments mechanically reinforce both individual fibers, as well as compositions including multiple fibers strung together in a single cord, by “crosslinking” the individual fibers with 3D graphene ligands. The combined result of these inventive efforts includes materials exhibiting superior mechanical strength and reduced mass relative to conventional carbon fibers.

The invention discloses a carbon fiber sizing agent composition suitable for thermoplastic resin, sized carbon fiber, a carbon fiber sizing agent as well as a preparation method and application of the carbon fiber sizing agent, belongs to the technical field of carbon fiber sizing agents, and solves the problem that a sizing agent in the prior art cannot meet excellent mechanical properties and high temperature resistance at the same time. The composition is prepared from the following components in parts by weight: 15 to 35 parts of modified polyaryletherketone resin matrix, 0.3 to 2 parts of neutralizer, 1 to 3 parts of emulsifier, 1.5 to 3 parts of defoaming agent and 57 to 80 parts of deionized water. The sizing agent containing the composition has good wettability and film-forming property on the surface of the carbon fiber, and meanwhile, the sizing agent is matched with other components with specific contents in the composition, so that the carbon fiber sizing agent containing the carbon fiber sizing agent composition has excellent heat resistance, can bear processing at the high temperature of 350 DEG C or above, and has good application prospects. And the composite material containing the sizing agent has excellent interlaminar shear strength.

The invention discloses a bamboo longitudinal and wood transverse composite whole container bottom plate and a preparation method thereof, and belongs to the field of bamboo-wood composite materials. The bottom plate is of a seven-layer alternate paving structure and is formed by compositing transverse wood veneer layers and longitudinal radial bamboo curtain layers, wood veneers are made of lignin modified polyurethane adhesive (reinforced by nano-silicon dioxide), and bamboo curtains are made of bamboo fiber nano-crystal reinforced soybean protein adhesive (cross-linked by genipin). Through continuous paving, fixed-length saw cutting and a'cold-in-cold-out 'hot pressing process (the pressure is 1.5-8.0 MPa, and the temperature is 140-220 DEG C), whole-piece production of any length is achieved. According to the technology, the bamboo-wood interface bonding problem is solved, the bending strength reaches 120 MPa, the interlayer shear strength is 7.8 MPa, the strength retention rate after damp-heat aging resistance is 90%, the formaldehyde emission is smaller than or equal to 0.05 mg / m < 3 >, the bio-based carbon content is 85%, high strength, weather resistance and environment friendliness are achieved, a traditional spliced container bottom plate can be replaced, the material utilization rate is increased by 20% or above, and the manufacturing cost is remarkably reduced.

The invention discloses a woven tape 3D simulation system based on finite element analysis, and relates to the technical field of woven tape simulation, multidirectional stress on a grid area can be accurately calculated by applying different types of force, comprehensive stress is constructed by using an equivalent stress theory, and the system can identify whether a stress field is smooth or not based on the comprehensive stress, so that the woven tape 3D simulation system can be used for simulating the woven tape. And a stress concentration area and a potential instability risk can be quickly found. The structure evaluation module monitors the relative slippage condition among yarns in the multilayer structure of the braid by regulating and controlling different vibration load conditions, calculates the interlayer shear stress, and fits and outputs a structure stability score in combination with an effect evaluation model, and the design can dynamically reflect the stability performance of the braid under the complex working condition, so that the stability of the braid under the complex working condition is improved. And a scientific basis is provided for optimizing design parameters (such as interweaving point density, yarn material and the like) of the braid.

The invention relates to the field of carbon fibers, and discloses a polyacrylonitrile carbon fiber precursor, a preparation method thereof and a carbon fiber. The method comprises the following steps: spinning stock solution is subjected to spinning to form stock solution trickles, the stock solution trickles are in contact with a coagulating agent in an air layer and then enter a coagulating bath to be coagulated; the coagulator is a small molecular alcohol compound. According to the method, the advantages of wet spinning and dry-wet spinning are combined, the high spinning speed can be kept, the groove structure can be formed in the surface of the protofilament, and then the interlaminar shear strength of the composite material can be improved.

The invention provides a method for improving the interface performance of an aramid fiber laminate composite material through high-temperature pretreatment and a preparation process of the aramid fiber laminate composite material, and relates to the field of performance improvement of composite materials. Comprising the following steps: S1, heating aramid fibers at 150-300 DEG C for 3-15 minutes, and immediately taking out the aramid fibers; s2, fully and uniformly coating epoxy resin on the aramid fiber obtained in the step S1; and S3, carrying out molding treatment on the aramid fiber obtained in S2 to obtain the aramid fiber composite material with improved interface performance. The simple high-temperature pretreatment method is adopted, the number of polar functional groups on the surface of the aramid fiber is increased, the resin impregnation degree of the aramid fiber and the bonding performance between fiber-resin interfaces are improved, and the interlaminar shear strength of the composite material is greatly improved.

The invention discloses a composite material fan blade layering design method in the technical field of aero-engine fan blade design, and the method comprises the following steps: S1, constructing a blade model, and carrying out optimization based on a model structure; s2, prepreg is selected, the curing thickness of a single layer of prepreg is obtained through a laminated plate curing process, a laying layer profile diagram is extracted according to the blade optimization model, and laying layers are grouped according to the height; s3, paving layers are uniformly arranged according to a height marshalling method under the paving layer design criterion condition, paving layer angles are given, whether the requirements are met or not is judged, and a preliminary blanking drawing is generated; and S4, carrying out cutting design on the prepreg according to the blanking drawing. According to the method, through parametric modeling and actual measurement data calibration, tenon extension design and layering angle distribution and sorting design are optimized, fiber continuity is ensured, process accumulative errors are eliminated, then, 90-degree layering is locally introduced to enhance out-of-plane rigidity, stress concentration is dispersed in combination with step transition treatment, and therefore the method has the advantages of being simple in structure and convenient to operate. And the peak value of the interlayer shear stress of a tenon-blade body transition area is reduced, and the impact resistance is improved.

The invention relates to the technical field of carbon fiber sizing agents, in particular to a preparation method and application of a self-emulsifying cationic waterborne polyurethane emulsion sizing agent. The preparation method comprises the following steps: firstly, preparing the cationic waterborne polyurethane emulsion by adopting a self-emulsifying method, then mixing the cationic waterborne polyurethane emulsion with the lubricant, the surfactant and the coupling agent, adding distilled water, and stirring and diluting to prepare the sizing agent. According to the cationic waterborne polyurethane emulsion prepared by the method disclosed by the invention, the performance of the emulsion is improved, and the cationic waterborne polyurethane emulsion can be prepared by changing different synthesis raw materials, the ratio of the raw materials and the content of a solid intermediate and introducing a nano SiO2 structure. The emulsion has different hydrophilicity and lipophilicity, different particle sizes and different heat resistance degrees, is applied to fiber production with different requirements, and has the properties of improving the chemical bonding property and wettability of a resin and fiber interface, improving the tensile strength of fibers, enhancing the interlaminar shear strength of composite materials and the like.

The invention discloses a carbon fiber anodized surface treatment device and a surface treatment method, the device includes an electrolysis unit for carbon fiber anodized surface treatment and a post-electrolysis waste gas treatment unit. The device can flexibly adjust the spacing of the impregnation rollers in the electrolytic cell, control the electrolysis time, oxidize each single filament evenly, and have a good electrolytic oxidation treatment effect. Active functional groups such as oxygen and nitrogen are introduced into the surface of the carbon fiber, and the interlayer shear strength of the carbon fiber composite material is significantly improved; the equipment manufacturing cost is low; the operation is simple, and it is easy to process a large number of carbon fiber bundles, which is suitable for batch production; the electrolysis device is equipped with an inlet suction hood, an outlet suction hood, and a movable cover plate, and a fan is used to extract the ammonia waste gas generated by the electrolysis device to the post-electrolysis waste gas treatment device equipped with a foldable cover plate to produce an acid-base reaction, effectively blocking the escape of waste gas, reducing environmental pollution, avoiding harm to the health of operators during operation, and ensuring safe production.

The invention provides toughened epoxy resin for a carbon fiber epoxy prepreg and a preparation method of the toughened epoxy resin, and relates to the technical field of high polymer material preparation. The preparation method comprises the steps of aminating phenyl polymethylsiloxane, modifying epoxy resin and preparing toughened epoxy resin. And aminating phenyl polymethylsiloxane: mixing phenyl trimethoxy silane, 3-aminopropyltriethoxysilane and a diluent, dropwise adding a catalyst, and adjusting the pH value after a reaction to obtain the amino-containing phenyl polymethylsiloxane. The epoxy resin is modified, wherein phenyl polymethylsiloxane containing amino groups and polyhedral oligomeric silsesquioxane are used as modifiers. And preparing toughened epoxy resin: mixing the modified epoxy resin, solid epoxy resin, a diluent, a curing agent and a flame retardant. The toughened epoxy resin prepared by the invention maintains a high glass transition temperature while toughening, and optimizes the interlaminar shear strength and flexural modulus of the carbon fiber epoxy prepreg.

According to the carbon fiber reinforced 3D printing wire rod and the preparation method thereof, the mechanical property of continuous carbon fibers and a resin matrix can be effectively improved, full transmission of loads in a composite material can be effectively guaranteed, and improvement of the overall performance of the composite material is guaranteed; meanwhile, the short carbon fibers are doped into the carbon fiber reinforced 3D printing wire rod, so that the fluidity of the short carbon fibers in a molten matrix can be effectively improved, and the mechanical property of the carbon fiber reinforced 3D printing wire rod can be effectively ensured; the composite treatment agent can effectively enhance the surface modification treatment effect on the short carbon fibers and the continuous carbon fibers, so that the combination effect of the short carbon fibers and the continuous carbon fibers with the thermoplastic resin is better; nickel hydroxide and polydopamine modification can fill the defects of the short carbon fibers, the interface bonding state of the short carbon fibers and the thermoplastic resin is improved, correspondingly, the deformation resistance is higher during external force loading, and the interlaminar shear strength can be improved to different degrees.

The invention belongs to the technical field of carbon fiber surface treatment, and particularly relates to a cross-linked polymer modified carbon fiber, a preparation method and a composite material. Aiming at the problem of insufficient interface bonding force between the existing polyarylsulfone / ketone thermoplastic sizing agent and the carbon fiber, the core of the invention is to apply a polyarylsulfone / ketone derivative of which a main chain or a side chain is provided with an electrochemically crosslinkable active group to the technical field of carbon fiber surface treatment. And constructing a covalent bond combined three-dimensional network structure coating on the surface of the carbon fiber in situ. According to the method, firm anchoring of the coating and the carbon fibers is achieved, and the interface load transmission efficiency and the interlayer shear strength of the carbon fiber / polyether-ether-ketone composite material can be remarkably improved. The method is mild in process condition, easy in parameter control and convenient in post-treatment, meets green manufacturing requirements, and has remarkable large-scale production advantages.

The invention discloses an interlayer shear performance evaluation method and device considering the pore type of a special-shaped ceramic matrix composite, equipment, a medium and a product, and the method comprises the steps: segmenting pores in a CT image through employing adaptive filtering, gray scale transformation and Otsu dual-threshold segmentation algorithms, and determining a pore segmentation image; carrying out quantitative description on distribution characteristics of pores with different scale forms in the pore segmentation image, determining a relationship between each pore type and pore box dimension in the pore segmentation image, and further determining detailed representation of the pores; performing short beam shear test on the special-shaped ceramic matrix composite test piece, and determining a linear fitting relationship between detailed characterization of pores and interlayer shear strength of the short beam shear test; the short beam shear test interlaminar shear strength of the to-be-tested special-shaped ceramic matrix composite material test piece is predicted. According to the method, the interlayer shear performance of the to-be-tested special-shaped ceramic matrix composite material test piece can be effectively evaluated based on detailed characterization of the pores.

The invention discloses layered surgical drape composite hot melt adhesive spraying equipment and method, and relates to the field of layered products, the spraying equipment comprises a workbench, a plurality of mounting racks mounted at the top of the workbench, and an adhesive spraying table mounted at the top of the workbench; a spraying mechanism is arranged on the top of the glue spraying table, a connecting block is fixed to the bottom end of a spraying cylinder, and an air curtain assembly is installed at the bottom of the connecting block. The device further comprises a control system, a three-axis translation mechanism and a clamping mechanism, wherein the three-axis translation mechanism and the clamping mechanism are installed on the installation frame. According to the requirement for interlayer shearing force of the surgical drape, the glue spraying amount is dynamically adjusted, selective gradient spraying control is formed, the interface bonding force is met, meanwhile, use of hot melt glue is reduced, and therefore in large-scale batch production, the requirement for economic benefits can be met, the consistency of bonding strength is improved, and the service life of the surgical drape is prolonged. And the overall quality and performance of the surgical drape are obviously improved.

The utility model belongs to the technical field of carbon fiber production equipment, and discloses a large-tow carbon fiber in-situ surface modification device. The device comprises a large-tow precursor frame, a bundling ring, a large-tow conveying roller set, a large-tow heating roller set, a carbon fiber surface oxidation heating loop, an in-situ modifier dipping spraying plate, a reaction furnace and a large-tow collecting roller set which are sequentially connected from front to back, and then the large-tow precursor frame, the bundling ring, the large-tow conveying roller set and the large-tow heating roller set are sequentially connected. The large-tow carbon fibers jointly pass through a large-tow precursor frame, a bundling ring, a large-tow conveying roller set, a large-tow heating roller set, a carbon fiber surface oxidation heating loop, an in-situ modifier dipping spraying plate, a reaction furnace and a large-tow collecting roller set in sequence. Through multi-aspect structural improvement, the structure of the surface modification device is simplified, the tensile strength and interlaminar shear strength of the carbon fiber composite material are effectively enhanced, the problems of insufficient reinforcement and low production efficiency of the original carbon fiber composite material are solved, and advanced manufacturing of the high-performance large-tow carbon fiber composite material is promoted.

The invention provides a system and a method for detecting the mechanical property of a micro area of a composite material structure, and belongs to the technical field of material mechanical testing equipment. Comprising a fixing base and testing equipment, a clamping device is arranged in the fixing base and used for fixing a tiny test piece, force generated by the testing equipment is transmitted to the tiny test piece, a pressing disc is arranged in the testing equipment and controlled by a servo motor to move, and force is applied to the tiny test piece fixed in the clamping device; and an improved short beam shearing method is adopted for interlayer shearing performance testing. The bottleneck problem in the aspect of testing the interlayer shear strength of the composite material in a specific small area in the current composite material industry is solved, an important testing means is provided for research and development of the composite material, and experiments prove that the measurement repeatability error of the system is smaller than 2%, the standard requirement is completely met, and the system has a wide application prospect.

The invention discloses a short fiber and polyurethane-based interlayer in-situ modification method for a composite material, and relates to the technical field of resin material modification. According to the method disclosed by the invention, the epoxy resin is synergistically modified by utilizing the discrete short carbon fibers and the microphase separation polyurethane, so that the interlayer performance of the continuous carbon fiber reinforced epoxy composite material laminated board is enhanced and toughened; the epoxy resin is toughened by adding microphase separation polyurethane, so that the interlaminar fracture toughness of the composite material is improved, in addition, a proper amount of discrete short carbon fibers are added into the epoxy resin, and the interlaminar shear strength of the composite material is improved by utilizing the high-strength characteristic of the short carbon fibers; the method has the advantages that the thickness is easy to control, operation is easy, cost is low and the like, the interlayer performance of the continuous carbon fiber reinforced epoxy composite material can be comprehensively improved, and the requirement of engineering application in the aerospace field for the interlayer performance of a laminated board can be met.

The invention discloses a preparation method of a PE bulletproof plate. The preparation method comprises the following steps: S1, preparing materials; s2, laminating and laying: pre-stretching or pre-heating the UHMWPE fiber non-woven cloth before laying by adopting a cross laying structure (1); (2) cleaning the mold, and laying a layer of demolding cloth; (3) a first layer of UHMWPE fiber non-woven cloth is laid, the fiber direction is set to be 0 degree, then a layer of resin film is laid, a second layer of UHMWPE fiber non-woven cloth is laid, the fiber direction is rotated by 90 degrees and is perpendicular to the first layer, and the steps are repeated; a multi-stage temperature-pressure curve is adopted in the hot press molding stage, the porosity can be effectively and remarkably reduced, the interlaminar shear strength (ILSS) is improved, the product size stability is extremely high, a cooling curve is designed according to the crystallization dynamic characteristics of resin during cooling, slow cooling is achieved in the crystallization temperature interval, and the product quality is improved. The resin is promoted to form a more perfect crystal structure with a more uniform size.

The invention relates to a continuous fiber reinforced thermoplastic pressure pipeline and a preparation method thereof, the continuous fiber reinforced thermoplastic pressure pipeline is provided with a core pipe inner layer, a core pipe outer layer, a continuous fiber winding middle layer and a maleic anhydride grafting modification interface layer, the continuous fiber winding middle layer is wound on the surface of the core pipe inner layer, and the maleic anhydride grafting modification interface layer is wound on the surface of the core pipe outer layer. The maleic anhydride grafting modification interface is a transition layer between the continuous fiber winding middle layer and the outer layer of the core pipe, and the continuous fiber winding middle layer comprises continuous fibers and a resin film. The invention has the following beneficial effects: 1, a special prepreg process is adopted, a maleic anhydride grafting interface layer is added, and gradient heating is carried out, so that the problem of fusion and combination of thermoplastic materials is solved, the interlaminar shear strength is 35.1-42.0 MPa, and the internal pressure resistance of the pipeline reaches 15.2-20.1 MPa, which is far higher than that of a traditional winding pipeline by 50-100%; 2, the strength and the cost are balanced through the hybrid design of the continuous fiber winding middle layer, and the cost is reduced by 30%-40% compared with that of a full carbon fiber reinforced pipeline;

Carbon composites, including carbon fibers in a binder matrix, exhibit unique, advantageous mechanical properties, including inter laminar shear strength, compression strength, and resistance to forces applied at various angles. These improvements allow use of less material while conveying improved strength in myriad practical applications, reducing overall financial cost of fabrication, distribution, and practical utilization. These advantages are optimized via utilizing fabrication techniques that incorporate carbon filaments into carbon fibers, preferably incorporating carbon filaments and / or graphene platelets into said fibers, and incorporating the composite fibers, filaments, and / or graphene platelets into a binder matrix. The filaments and graphene platelets mechanically reinforce individual fibers, structures including multiple fibers strung together in a single cord, and the binder matrix, by “crosslinking” the individual fibers and / or fibers and binder matrix, e.g., with filaments and / or graphene ligands. The result includes materials exhibiting superior strength and reduced mass relative to conventional carbon fibers in a binder matrix.

The utility model discloses a carbon fiber prepreg cloth preparation device, and particularly relates to the field of carbon fiber processing, the carbon fiber prepreg cloth preparation device comprises a workbench, the upper end of the workbench is provided with a connecting assembly, the connecting assembly comprises a mounting rack, the upper end of the mounting rack is fixedly provided with an air cylinder, the bottom of the air cylinder is sleeved with an air rod, and the outer part of the air rod is connected with a spring in a surrounding manner; a connecting plate is fixedly connected to the bottom of the air rod, and connecting frames are symmetrically and fixedly arranged at the two ends of the bottom of the connecting plate. According to the utility model, through the arrangement of the connecting assembly, the carbon fiber prepreg cloth is moved into the resin soaking tank through the connecting rod for soaking operation, and in the soaking process, surface and internal pores of carbon fibers can be fully soaked, and gaps among the fibers can be filled, so that good physical contact is formed between resin and the carbon fibers; and the resin is subjected to a cross-linking reaction in subsequent curing, and is tightly combined with the carbon fibers, so that the mechanical properties such as interlaminar shear strength and tensile strength of the composite material are improved.

The invention discloses an interlaminar shear test method for an asphalt mixture composite board. The method comprises the following steps: preparing an asphalt mixture composite board test piece; putting the obtained asphalt mixture composite board test piece into an environmental box for heat preservation; the testing machine is adjusted to the testing temperature, and the asphalt mixture composite board test piece obtained after heat preservation is placed on a special clamp; vertically and downwards loading the asphalt mixture composite board test piece at a constant speed, and collecting pressure load and vertical displacement; and calculating the shear strength and the interlayer bonding coefficient. According to the interlayer shear test method for the asphalt mixture composite board, the problem that an interlayer shear test method special for the asphalt mixture does not exist in the prior art is solved.

The invention provides a method for improving the high-temperature interface strength of a quartz fiber reinforced polyimide resin composite material. The method comprises the steps of fiber cleaning, fiber surface activation, fiber surface grafting treatment and composite material preparation. Taking a quartz fiber reinforced PMR type polyimide resin composite material as an example, the bending strength of the composite material prepared by the method is greater than or equal to 373.5 Mpa under the test condition of 350 DEG C / 20 min, and is improved by 46%; the interlayer shear strength is greater than or equal to 34.5 MPa and is improved by 43%, and the dielectric constant is less than or equal to 3.40. The method solves the problems of poor interface bonding strength, low mechanical strength and poor structural stability of the quartz fiber reinforced polyimide resin-based composite material under the long-time high-temperature working condition, and is simple, easy to operate and suitable for batch production and application.

The invention discloses a high-molecular-weight thermoplastic phenolic resin with a narrow molecular weight distribution and a preparation method thereof. The resin preparation method comprises two steps, namely a polymerization process and a xylene extraction process. The invention uses dihydroxydiphenylmethane as a starting raw material, thereby ensuring that the resin obtained by polymerization has a narrower molecular weight distribution than that of a traditional phenolic resin. Furthermore, xylene extraction is performed to remove part or most of the low-molecular-weight fractions in the resin, thereby increasing the average molecular weight of the resin while further narrowing the molecular weight distribution of the resin, thereby achieving the purpose of significantly improving the charring rate of the resin. The thermoplastic phenolic resin prepared by the invention has a weight-average molecular weight of more than 2600 g / mol and a molecular weight distribution index as low as 1.79. The charring rate of the resin increases with increasing molecular weight and narrowing molecular weight distribution. After the resin is cured with hexamethylenetetramine, the charring rate can reach a maximum of 63.0%, and the interlaminar shear strength of the carbon fiber reinforced composite material reaches 55 MPa.

The present invention proposes a method for measuring and calculating the interlaminar shear strength of heterogeneous multilayer composite plates, which is used to solve the problem that the existing interlaminar shear strength test method of composite materials is only applicable to single-layer composite plates or isotropic laminates. The steps of the present invention are: starting from the pure bending theory, a normal stress calculation formula for pure bending of a rectangular cross-section composite plate composed of three layers of plates with different moduli and different thicknesses is constructed; according to the normal stress calculation formula, a shear stress calculation method for the neutral plane position and any position in the thickness direction of the composite plate is established; and the calculation formula for the normal stress, neutral plane position and interlaminar shear stress distribution of an n-layer rectangular cross-section composite plate in pure bending is derived. The present invention combines the maximum load and interlaminar failure position measured by the three-point bending test to accurately calculate the shear stress distribution and interlaminar shear strength of the heterogeneous multilayer rectangular cross-section composite plate; it breaks through the limitations of the existing interlaminar shear strength test method and fills the gap in this field.

This application relates to the field of household appliance technology, disclosing a panel and its molding process, and a household appliance. The panel includes: a fiber composite material layer; and a magnetic insert located on one side of the fiber composite material layer in the thickness direction. The magnetic insert includes a magnetic material and a resin encapsulating the magnetic material. The resin encapsulating the magnetic material can chemically react with the resin of the fiber composite material layer, thereby enhancing the bonding strength between the fiber composite material layer and the magnetic insert, eliminating the physical interface between the fiber composite material layer and the magnetic insert, and improving the interlayer shear strength. This completely solves the problems of panel delamination and warping caused by the difference in thermal expansion coefficients due to the addition of metal sheets in traditional processes. Moreover, the connection between the fiber composite material layer and the magnetic insert can be achieved by utilizing the chemical reaction between the resin encapsulating the magnetic material and the resin of the fiber composite material layer, eliminating the need for additional adhesive films or mechanical connectors.

The present invention discloses a carbon-carbon composite material preform and a preparation method thereof, which relates to the technical field of composite materials. The pores of the preform are filled with short-cut fibers, and the density of the obtained preform is increased. Compared with the traditional carbon fiber preform, the density of the preform is deposited to 1.6g / cm 3 The carbon-carbon composite material preparation cycle can be shortened by approximately 50%. Oblique needling of the preform, including the chopped fiber filling, increases the number of fibers in the preform's longitudinal direction, converting fiber shearing into fiber tension. This significantly improves the preform's interlaminar shear performance, increasing the interlaminar shear strength of the deposited carbon-carbon composite material by approximately 15%.

The invention discloses a method for evaluating seawater resistance of a cyanate ester-based composite material for a structural material, and belongs to the field of material performance testing, and the method comprises the following steps: S1, preparing a sample plate of the cyanate ester-based composite material for seawater resistance testing, and cutting the sample plate into a sample sheet I, a sample sheet II and a sample sheet III; s2, soaking the sample piece I, the sample piece II and the sample piece III, and sampling and testing at different time nodes; s3, obtaining a fitting equation about the water absorption rate, the interlayer shear strength and the glass transition temperature; s4, converting into a long-time fitting equation; s5, calculating an evaluation score; s6, comparing the evaluation score S with the required score of the allowable value of the cyanate ester matrix composite to obtain an evaluation conclusion; the evaluation score is calculated through fitting equations corresponding to the water absorption rate, the interlaminar shear strength and the glass transition temperature, and the method is used for predicting the seawater resistance of the cyanate ester matrix composite for the structural material.