8 results about "Matrix cracking" patented technology

The invention discloses a method for evaluating the residual strength of a multi-scale fiber-reinforced flexible pipe under a stretch-bending load, and relates to the technical field of structural strength evaluation of ocean engineering composite materials, and the method comprises the following steps: extracting fiber distribution characteristics by adopting digital image processing based on a scanning electron microscope image; a Monte Carlo method is combined to construct a two-dimensional RVE geometric model of the fiber reinforced structure containing the damp-heat degradation, and macroscopic elastic parameters are predicted; a VUMAT user material subprogram containing dynamic damage is written based on Fortran, damage starting and evolution failure criteria of a fiber reinforced structure are embedded, and the nonlinear coupling evolution process of multiple damage modes such as fiber fracture, matrix cracking and interface debonding is simulated. According to the method, a material-damage-response multi-scale analysis framework is constructed by coupling microscopic material components, a microscopic damage model and macroscopic pipeline structure analysis, the problem that a traditional method lacks multi-scale damage coupling analysis under a complex load is solved, and the residual strength evaluation precision of the pipeline under the action of a stretching-bending combined load is improved.

This invention relates to a silicon carbide ceramic matrix composite material reinforced with unidirectional silicon carbide fibers and its preparation method, comprising: 1) winding silicon carbide fibers in the same direction to obtain a unidirectional tape; 2) depositing an interface phase on the surface of a single fiber using chemical vapor deposition; 3) preparing a prepreg slurry by mixing carbon powder, dispersant, etc.; 4) impregnating the unidirectional tape with the slurry to obtain a prepreg tape; 5) layering the prepreg tape and the unimpregnated unidirectional tape at a layer ratio of 1:1 to 16:1 and a silicon carbide fiber angle of 0° to 90°; 6) obtaining the composite material through curing, pyrolysis, and melt infiltration densification. This invention breaks away from the traditional single-layer layup mode, constructing a continuous gas flow path through mixed layering, guiding process gas generation, solving the drawbacks of high porosity and matrix cracking, optimizing the material's stress state, and obtaining a composite material with both low density and high compactness, excellent mechanical properties at room temperature and high temperature, and excellent oxidation stability, shortening the preparation cycle, and meeting extreme service requirements.

The application discloses a continuous fiber 3D printing high-bearing self-monitoring deformation ceramic matrix composite truss and a preparation method and application thereof, and relates to the technical field of additive manufacturing. The truss comprises top chords, bottom chords and built-in units arranged between the top chords and the bottom chords; the built-in units comprise one or more shapes of units selected from a triangle, a trapezoid, a circle and a rhombus; the structure of the truss comprises single-layer or multi-layer trusses; and the constituent material of the truss comprises continuous conductive fibers, pyrolytic carbon interfaces and precursor ceramic matrices. The application deposits a conductive layer on the fiber surface and the matrix crack of the composite material, so that an electrically poor ceramic matrix composite forms an electrically conductive network in the interior, the electrical conductivity of the ceramic matrix composite is improved, the ceramic matrix composite is endowed with piezoresistive performance, and bearing monitoring integration is realized.

The application discloses a kind of oxidized coal pitch nanocarbon material modified water-related polymer friction pair materials and preparation method, belong to polymer material technical field.The water-related polymer friction pair material of the present application is made of soluble oxidized pitch nanomaterial of formic acid / hydrogen peroxide oxidation system oxidation coal pitch and ultra-high molecular weight polyethylene matrix.The present application utilizes the gap of polymer molecular chain of soluble oxidized pitch nanomaterial of ultra-small structure, and plastic rheology and adhesive wear of material are reduced in friction process by steric hindrance and interface anchoring effect;Combination of the "nanometer reinforcing network" formed by uniform dispersion can effectively transfer friction stress, avoid the matrix cracking caused by local stress concentration;While the nanometer size of soluble oxidized pitch nanomaterial and carbon-based characteristics give it unique dynamic lubrication function, its surface abundant functional groups can form high density, strong adhesion transfer film, significantly improve the wear resistance and service life of composite material.

An embedded thin-walled reinforced structure made of hybrid materials and its preparation method are disclosed. The structure includes a lower composite material layer and a metal layer, the metal layer being disposed on the upper surface of the lower composite material layer and having a hollow structure. It also includes an upper composite material layer covering the upper surfaces of the metal layer and the lower composite material layer, and completely encapsulating the metal layer. A resin matrix is ​​further included, filling the voids between the lower composite material layer, the metal layer, and the upper composite material layer. This structure meets the performance requirements of composite material shell structures in terms of bending resistance, lightweight, impact resistance, and energy absorption characteristics. It also provides a connection scheme between the thin-walled hybrid material member and the composite material shell, ensuring connection strength and reliability without causing damage to either structure due to processing techniques. Such damage includes, but is not limited to, fiber breakage and matrix cracking of the composite material, as well as the initiation of cracks in the metal.

The application discloses a composite material fracture energy calculation method considering reinforcement-matrix interface dispersion, and comprises the following steps: S1, a matrix crack fracture energy model is established; S2, a reinforcement-matrix interface fracture energy model is established; S3, a composite material fracture control equation model is established; S4, a composite material critical energy release rate is modified; S5, the interface phase field, the displacement field and the crack phase field in the composite material fracture control equation are discretized by using the finite element method, and an incremental iteration is carried out, so that the crack propagation in the composite material considering the interface dispersion is calculated. Through the adoption of the phase field model, the advantages of realizing the micro-to-macro multi-scale simulation are utilized, the properties of the interface in the composite material are associated with the properties of the matrix, that is, the interface crack propagation and other fracture properties of the composite material under the action of the load are dispersed to the surrounding matrix in the form of a continuous exponential function, and a mechanical model for more accurately predicting the mechanical behavior and fracture evolution of the composite material is established.

This invention relates to the field of building materials, specifically to a steel slag-based low-carbon ultra-high-performance concrete composite material and its preparation method. The composite material comprises, by weight, 30-50 parts mineralized steel slag powder, 20-30 parts cement, 10-15 parts silica fume, 5-10 parts fly ash, 1-3 parts water-reducing agent, 15-25 parts steel fiber, and 10-15 parts water. The mineralized steel slag powder is obtained by biochemical mineralization of steel slag powder through a mixture of alkaline bacterial solution containing Bacillus pasteurella and a calcium source substrate. A calcium carbonate crystal layer is deposited in situ on its surface, and residual bacterial protein adheres to the pores, forming a multi-scale stacked cementitious skeleton with silica fume and fly ash. The preparation includes mineralization, dry mixing, slurry preparation, fiber addition, and curing steps. This invention eliminates the free calcium oxide expansion source, preventing matrix cracking, fills the pores on the steel slag surface, and strengthens the interfacial bonding strength.

A coated fiber structure for use in a ceramic matrix composite comprises a fiber extending along a fiber axis and an interface coating arrangement applied to and circumscribing the fiber. The interface coating arrangement comprises: a first boron nitride layer extending coaxially about and in direct contact with the fiber, a first silicon-doped boron nitride layer extending coaxially about and in direct contact with the first boron nitride layer, a carbon layer extending coaxially about and in direct contact with the first silicon-doped boron nitride layer, a second boron nitride layer extending coaxially about and in direct contact with the carbon layer, and a second silicon-doped boron nitride layer extending coaxially about and in direct contact with the second boron nitride layer. A silicon content of the first silicon-doped boron nitride layer is higher than the silicon content of the second silicon-doped boron nitride layer.