Structure Of Composite Materials Research Articles

Preparation and properties of high-efficiency lignin-carbon based photocatalytic composites for the degradation of dye wastewater under visible light

Lignin-based carbon/cadmium sulfide (LCS) composite photocatalytic materials with excellent porous structures were prepared by simple carbonization and in situ precipitation using lignin from a wide range of sources as a carbon source. The CdS nanoparticles were uniformly fixed in LC, which improved the sunlight absorption ability and good stability of the photocatalyst. The effect of different factors on the pore structure of composite photocatalytic materials was investigated. The results showed that the obtained LCS composites had the maximum specific surface area (334.841 m2·g−1) and porosity (0.4406 mL·g−1) when the mass ratio (the lignin: the templating agent) was 2:1 and the carbonization was carried out at 600 °C for 1.5 h (LCS-600-1.5-2). Compared with pure CdS, the photodegradation performance of the prepared LCS under simulated sunlight (500 W Xe lamp) irradiation was significantly improved. The degradation rate of methylene blue (MB) and methyl orange/methylene blue (MO/MB) by LCS reached 91.7% and 90.8% in 2 h, respectively. The material stability test of LCS showed that LCS has good acid–base stability, and the degradation rate of MB remained above 80% after 5 cycles. The LCS prepared from lignin biomass, improved the dispersion uniformity of cadmium sulfide, reduced the recombination of photogenic electron hole, enhanced the photocatalytic performance under visible light, which greatly expanded the application of photocatalytic material.

INVESTIGATION OF THE DENSITY OF CCCM AND ITS INFLUENCE ON SPECIFIC VOLUME ELECTRICAL RESISTIVITY

This article investigates the structure and properties of carbon-carbon composite materials (CCCM), where the carbon matrix is formed by the deposition of pyrolytic carbon in the porous volume of a carbon fiber preform using thermogradient gas-phase pyrolysis densification technologies. The results of studying the apparent density of CCCM by hydrostatic methods and its influence on the specific volume electrical resistivity of the material are presented. The conducted study established that the specific volume electrical resistivity of CCCM significantly depends on a number of factors, one of which is the material density. An increase in the apparent density of the material leads to a decrease in its porosity, which, in turn, affects the decrease in electrical resistance. It is emphasized that density control becomes a key factor in ensuring optimal electrical conductivity of carbon-carbon composite materials. It is shown that the densification of CCCM significantly improves the structure of blanks and crucibles, increasing their physical and operational characteristics. This makes them more suitable for use in high-temperature conditions, aggressive environments, in the production of heat-resistant components and other high-tech areas. Repeated densification of CCCM revealed a significant impact on the quality of the material. It is shown that an increase in density after additional densification leads to a decrease in porosity, improvement of mechanical properties and a change in the pore distribution in the material, which positively affects its porosity and strength. Bench tests of model samples made of CCCM showed that an increase in the apparent density of the material leads to a decrease in its electrical resistance. To ensure control in industrial practice, an effective and affordable method for assessing the degree of completion of crystalline transformations and determining the degree of graphitization during high-temperature treatment of carbon materials is recommended to compare the specific volume electrical resistivity of the working sample with the reference one. The importance of controlling the parameters of density, porosity, and electrical resistance to optimize technological processes and ensure high quality of final products is emphasized. The obtained data can be useful for applications in various industries.

Applying the principles of digital materials science to study and analysis the structure of structural composite materials

Applying the principles of digital materials science to study and analysis the structure of structural composite materials

Damage and Failure Modeling of Composite Material Structures Using the Pam-Crash Code

Simulating composite material structures requires complex constitutive models, which normally require fine meshes to obtain an accurate prediction of their behavior. Pam-Crash software has been used for several years in the automotive industry and has been proved to be an efficient tool for simulating metallic structures, returning good correlations in a fast computational time. However, constitutive models for composite materials in Pam-Crash present some difficulties: some materials are not able to be suitably modeled and the predictive results depend on the mesh refinement. This work proposes a solution for predicting the progressive damage of composite materials in Pam-Crash, which scales the energy dissipated by the damage mechanisms and checks the viability of modeling the material behavior, taking into account the recommended size of finite elements in the automotive industry. The proposed solution is applied for the simulation of Open Hole specimens to evaluate the ultimate strength consistency. After this, it is applied for the simulation of Compact Tension specimens to check the consistency of crack propagation behavior. By considering the target size of the finite elements in the material card definition, the predictions demonstrate great improvement in the equivalence in results between different mesh refinements. Finally, the solution is applied to simulate impact tests on large structures. Good correlations with experimental data are obtained in fast computational times, making this methodology a candidate for application in composite-related automotive simulations.

Investigation into the mechanical properties and impact tendency of coal-rock composite structures with peridynamics: A study on predicting the occurrence tendency of dynamic pressure in coal-rock structures.

Due to the difficulty in predicting the occurrence of rockburst in deep mining areas,this paper proposes that the use of Peridynamics to analyze the mechanical characteristics of coal-rock composite structures under loading conditions from the perspective of energy, Determine the impact tendency of coal rock composite structures by combining rock elastic deformation energy index (WET) and rock impact energy index (WCF); Use Lammps software to simulate the loading of composite structural materials and compare and verify with experimental results, to more accurately determine the tendency of rockburst occurrence in different coal-rock composite structures.The results indicate that after the specimen reaches the yield stress, the sample exhibits an "X" shaped failure. The coal body has a significant impact on the overall model's fragmentation, and different combination states and ratios can affect the degree of damage in the coal-rock composite structure. which has important theoretical value for rock mechanics research. The research results can reduce the occurrence of rockburst accidents, the difficulty of mine support, and the cost of mining engineering, as well as improve mine safety levels.

Pre-processing for isogeometric analysis of laminated composites

Composites are materials resulting from the mixture of two or more components, usually a polymer matrix reinforced with synthetic fibers, used to build stronger structures capable of withstanding heavy loads and unfavorable environmental conditions. Laminated shells are made of layers of fiber-reinforced composite material, stacked in a specific sequence to ensure good structural performance. The analysis of these structures is predominantly done using the Finite Element Method, a conventional approach used to solve these problems, approximating both the displacements and the geometry of the structure using polynomial functions. A more recent alternative is Isogeometric Analysis (IGA), which uses rational functions to approximate the displacements and geometry of the structure. This ensures that the geometry of the problem is exact, regardless of the level of discretization used. The aim of this work is to study the use of NURBS surfaces in the context of isogeometric analysis of laminated structures. The theoretical and practical aspects of these representations will be studied, with emphasis on the pre-processing stage of the numerical analysis. In this context, the pre-processing of the numerical model of the composite material structure is carried out in the academic software FEMEP (Finite Element Method Educational Computer Program), written in the Python language. The software's graphical interface has been extended to handle models of laminated composite plates. The numerical model is processed using the FAST tool, where the pre-processing program writing routines have been implemented. In the post-processing stage, the simulation results are visualized using the Nlpos tool. The system developed was used in examples of laminated plates, demonstrating the system's capabilities.

N-doped carbon sphere-SiO2 composite structure materials with high adsorption rate and low regeneration energy consumption for CO2 capture from flue gas

N-doped carbon sphere-SiO2 composite structure materials with high adsorption rate and low regeneration energy consumption for CO2 capture from flue gas

The Role of Micro Propulsion in Enabling Autonomous Operations of Nanosatellites

Micro-Electro-Mechanical Systems (MEMS)-based propulsion devices have significant potential for providing high specific power. The application of Micro Power Generation technology to space propulsion systems can enhance orbit and station-keeping capabilities, potentially at lower costs. New-generation spacecraft and satellites are becoming smaller and require micro-propulsion systems for all aspects of their operations. The development of micro-propulsion systems with associated combustors for micro-electricity generation, utilizing liquid fuel, presents major challenges in fuel injection, mixing, combustion, and chemical reactor systems. A micro-spacecraft with high-accuracy station-keeping and attitude control capabilities needs to have low mass and deliver small impulses. Each nanosatellite will weigh a maximum of 10 kg, including the propellant mass. Provisions for orbital manoeuvres, attitude control, multiple sensors, and instruments, along with full autonomy, will result in a highly capable miniaturized satellite. All onboard electronics will endure a total radiation dose of 100 k rads over a two-year mission lifetime. Nanosatellites designed for in-situ measurements will be spin-stabilized and equipped with a complement of particles and fields instruments. Nanosatellites intended for remote measurements will be three-axis stabilized and equipped with imaging and radio wave instruments. Key technologies under development include: advanced, miniaturized chemical propulsion systems; miniaturized sensors; highly integrated, compact electronics; autonomous onboard and ground operations; miniaturized onboard orbit determination methods; onboard RF communications capable of transmitting data to Earth from significant distances; lightweight and efficient solar array panels; lightweight, high-output battery cells; a miniaturized heat transport system; lightweight yet strong composite materials for nano-satellite and deployer-ship structures; and simple, reusable ground systems.

Design, Preparation, and Analysis of the Acoustic Performance of Waste Hemp/PLA Fiber Sound-Absorbing Composites with Different Bionic Structures

Noise pollution is becoming more and more serious, and the environmental friendliness of building materials could be better. To solve these problems, waste hemp fibers were used as reinforcement and polylactic acid (PLA) fibers as matrix. Sustainable biodegradable sound-absorbing composites with different bionic structures were prepared by carding and hot press molding process. The sound absorption properties of bionic structural composites with smooth surface,triangular wedge surface, trapezoidal prismatic surface, sinusoidal wave surface,cylindrical pit surface, and rectangular raised surface were tested. Composites were 30mm in thickness and 100mm in diameters.The bionic sound structure models was constructed according to the extracted bionic structure. The sound performance of the sound-absorbing composites was analyzed by finite element method simulation. The effects of bionic structure and sound characteristic parameters on the sound absorption performance of the composites were investigated and the sound absorption mechanism of the sound composites with bionic structures was revealed. Then the model of the cylindrical pit surface was used as a research object further to optimize the sound absorption performance. The results revealed that the optimized bionic structural composite materials had a sound absorption performance grade of II, with a sound absorption average (SAA) coefficient in the mid-frequency range of 27.16% higher than that of the smooth surface composites. The noise reduction coefficient was 0.603, and the SAA coefficient was 0.583.The results not only find a new way to recycle the waste hemp fibers, but also provide an experimental basis and theoretical basis for the optimization of sound absorption composites in building applications.

Исследование влияния жидкой среды на механические характеристики полимерных композиционных материалов

The problem of determining the ability of a liquid to penetrate into the structure of a composite material prepared using reinforcing glass fabrics and a polyester binder is solved. The determination of the ability of water to penetrate into the structure of samples cut from a common plate of polymer composite materials (PCM) is carried out by determining the change in weight of samples before and after their immersion in a container with a liquid medium (water) for a certain period of time. The ability of water penetration into the composition of this material has been established depending on its structure, that is, on the location of the reinforcing material. The mechanical properties (tensile, compressive and bending strength) of a composite material after its removal from a liquid container are presented. The problem of the possibility of the effect of processing the ends of cut test samples with polyester resin on the ability of liquid penetration into the composition of a PCM is solved. For this purpose, samples cut from a common plate were immersed in containers with water, while the ends of one batch of samples were coated with polyester resin, and the other batch was uncoated. The influence of the presence of samples in a liquid medium (water) with a certain ratio of layers of reinforcing material (glass wool and roving fiberglass) on their mechanical characteristics during bending, stretching and compression has been established. The test results of the samples are presented, which showed a direct dependence of the tensile strength and destructive force on the number of roving layers in the PCM structure of the samples whose edges were treated with polyester resin. During the experiments, the ability of liquid penetration into the structure of composite materials and changes in mechanical properties as a result of immersion of these materials in a liquid medium were determined. The obtained results of experimental tests of samples made of PCM with various reinforcement schemes will justify their widespread use in ship hull structures, in particular, as a material for the manufacture of ship tanks.

Experimental investigation on the local damage behavior of reinforced concrete-stainless steel membrane composite material structures subjected to large-scale missile impact

Large-scale membrane liquefied natural gas (LNG) storage tanks may experience missile impacts caused by wind or explosions during operation. However, the damage and dynamic response of reinforced concrete (RC) and stainless steel membrane (SSM) composite structures of the tank under such impacts remain unclear. This study addresses this gap by investigating the damage characteristics and dynamic responses of RC-SSM composite structures through eight large-scale missile impact tests. The findings reveal that the RC plates exhibit penetration, scabbing, and perforation damage. Failures at the interface between the SSM insulation system and the RC component are attributed to reverse tensile stress exerted on the rear surface of the RC plate, coupled with rebar-induced actions, ultimately resulting in detachment of its protective layer. Additionally, indirect effects from concrete conical plugs and scab fragments contribute to damage in the SSM insulation system. The impact loads cause the corrugations and knots of the stainless steel membrane to flatten, effectively absorbing a significant amount of impact energy. This observation suggests that the corrugated membrane exhibits superior impact resistance compared to flat films. To meet the requirements of "airtightness," this study establishes five damage modes and proposes an evaluation methodology for RC-SSM composite structures under large-scale missile impacts.

Nanoporous and IPN structural composite material of cyanate ester modified by hollow silica and polyimide

Cyanate ester resin (CE), a high-performance and low dielectric materials, was modified with amino hollow silica (HSMs-NH2) and polyimide resin (PI) to form an IPN structure. Reducing the crosslinking density of the composite system and accompanying with its steric hindrance effect, PI increased the free volume of the composite material. The hollow structure introduced by HSMs-NH2 further enhanced a low dielectric property. IPN structure and HSMs-NH2 also significantly improved the impact toughness of HSMs-NH2/PI/CE composites. The bonding between the Si–O–Si and HSMs-NH2 offered an excellent heat resistance and as well surface bonding capability to matrix, which reduced the decomposition and effectively improved their thermal stability. Simultaneously, profited by the hydrophobicity of Si–O–Si, HSMs-NH2/PI/CE composite materials enabled to keep low dielectric properties in humid environments.

Energy storaging multifunctional carbon fiber composites based on Nano‐SiO2 reinforced epoxy matrix structural electrolytes

AbstractMultifunctional carbon fiber composite materials capable of storing energy and carrying structural loads have advantages for aerospace structures. In this paper, a structural supercapacitor that consists of an epoxy‐based solid polymer electrolytes (E‐SPEs) and carbon fiber was proposed. To develop an E‐SPEs with better mechanical properties and ionic conductivity, Nano‐SiO2 was introduced into the solid polymer electrolytes. Nano‐SiO2 reinforced E‐SPEs (Nano‐SiO2/E‐SPEs) show improved mechanical properties (Young's modulus [E] = 0.85 GPa) and ionic conductivity (4.99 × 10−4 S cm−1), compared to E‐SPEs without Nano‐SiO2. Structural supercapacitors were further prepared by combining E‐SPEs with carbon fibers. The structural supercapacitor prepared with Nano‐SiO2/E‐SPEs exhibits the higher power and energy density (261.93 W kg−1 and 2.11 Wh kg−1) compared to the structural supercapacitor prepared with E‐SPEs without Nano‐SiO2 (51 W kg−1 and 0.34 Wh kg−1), indicating improved mechanical and energy storage properties for structural supercapacitors after incorporation of Nano‐SiO2. This strategy has great potential in enhancing performance of structural energy storage composite materials for application in next‐generation aerospace vehicles.

Open source tool for Micro-CT aided meso-scale modeling and meshing of complex textile composite structures

Volumetric image-based modeling of textile reinforcements and composites is favored over ideal geometric modeling because of its ability to represent complex structures in sufficient detail. Although several approaches were devised, there is still a scarcity of dedicated tools capable of effectively transferring pertinent information from images to high-fidelity models. This work presents the open source project, PolyTex, a Python-based object-oriented application that establishes a streamlined and reproducible workflow for such tasks. Dual kriging serves as the foundational theory for the parametric approach developed to represent, simplify, and approximate the morphology and topology of fiber tows. The code takes two types of input, either an explicit representation of tow geometry using point clouds or implicit representations, such as image masks representing fiber tows separately with grayscale values. Tailored APIs allow for smooth integration between PolyTex’s modeling capabilities and the simulation environments offered by OpenFOAM and Abaqus. Case studies on virtual testing of textile permeability were presented to demonstrate this capability. The modular and object-oriented design makes PolyTex a highly reusable and extensible tool that allows users to create a customized pipeline.

Neutron Radiography: an Overview

Although similar to X-ray and gamma-ray radiography, neutron radiography (NR) is a separate NDT method that evaluates structures somewhat differently and reveals unique internal characteristics that are often difficult to interpret using other NDT methods. Solid metals, for example, can appear nearly transparent with NR, as when analyzing hydrogenous materials in composite structures or assemblies. Although NR got its start in the mid-1900s, the technology took several decades to mature and migrate out of academic research and government experimentation and into the profession of NDT. Even today, NR has limited applications but is gradually gaining traction, especially where conventional X-ray and gamma-ray imaging are not possible. This article provides an overview of the method, along with recent content from ASNT’s media channels.

K+-doped lead-free Cs3Bi2Br9 nanocrystals Enable efficient blue emission and Ultra-stability

A new type of lead-free perovskite Cs3Bi2Br9 nanocrystal (NCs) was synthesized by thermal injection method at 190 °C, according to X-ray diffraction and theoretical analysis, the Cs3Bi2Br9 NCs belongs to the monoclinic system C12/c1. We report for the first time that the luminescence intensity of broad-peak-emitting Cs3Bi2Br9 is significantly improved by doping with K+, and the full-width at half maximum (FWHM) of sample Cs3Bi2Br9:0.2K+ is 124 nm. Herein, the stability of Cs3Bi2Br9:xK was monitored and found to have excellent environmental stability, thermal stability, and photostability. In addition, Cs3Bi2Br9:0.2K was coated outside Sr2MgSi2O7:Eu2+,Dy3+ (SMS) to form a core-shell structure composite material Cs3Bi2Br9:0.2K+/SMS@SiO2 and achieved fine tuning of the afterglow color. This work increases the luminescence intensity of Cs3Bi2Br9 by ion doping and exhibits excellent stability, in addition to the cladding of lead-free perovskites with long afterglow materials provides a new application strategy for lead-free perovskites.

In situ catalyzed growth of carbon nanotube with asphalt cladding as a bicarbon synergistic framework of silicon anodes for lithium-ion batteries.

Silicon, as the most promising advanced anode material for lithium-ion batteries, faces challenges in large-scale industrial production due to the significant volume expansion effect. In this investigation, Si/CNTs/C composite materials were effectively produced through high-temperature carbonization utilizing asphalt, silicon, hexahydrate ferric chloride, and melamine as primary elements. The distinctive dual-carbon framework of asphalt-derived carbon and carbon nanotubes alleviates the volume expansion of silicon, thereby stabilizing the composite material's structure. Testing the electrochemical performance reveals that the Si/CNTs/C composite material exhibits a reversible specific capacity of 1187 mAh g-1 with a capacity retention rate of 92.6% after 150 cycles at a current density of 0.2 A g-1. Even after 500 cycles at a current density of 1 A g-1, it sustains a specific capacity of 879.4 mAh g-1 with a capacity retention rate of 87.9%, showcasing outstanding electrochemical performance.

MANUFACTURING METHODS OF FIBER REINFORCED POLYMER COMPOSITES

Before talking about polymer matrix composites, it is necessary to examine the structure of composite materials and to get to know composite materials. When we look at composite materials; composites are considered one of the most important members of the advanced material group. Composites; are artificial materials formed by combining two or more materials at a macro level in order to collect their properties in a single material while preserving their components. Polymer matrix composite materials are used in many areas today. For the production of polymer matrix composites, it is necessary to select the appropriate matrix reinforcement and additional materials and to structure these materials correctly. One of the most important steps during production is polymerization. There are various methods that can be used when producing polymer matrix composites. These methods can be listed as; hand lay-up method, spray method, press molding method, transfer molding method, vacuum molding method, cold molding method, autoclave molding method, filament winding method and matrix injection method. Keywords: polymer composites, fiber-reinforced composites, particle-reinforced composite.

Harmonizing lightweight and ablation resistance: Design and performance of multilayer composite insulation materials for solid rocket motors

AbstractThe realization of lightweight insulation materials is often accompanied by a decrease in ablation performance. Coordinating the contradiction between lightweight and ablation resistance is the key to the development of thermal protection technology. Addressing the need for high‐performance insulation materials within solid rocket motors (SRMs) combustion chambers, we designed three multilayer composite structural insulation materials and studied their properties. The results show that among these constructed multilayer composites, the bilayer structure exhibited the lowest density at a mere 0.72 g/cm3, marking a 27% reduction compared to the basic structure. Remarkably, the bilayer configuration demonstrated superior ablation resistance, showcasing a 25% decrease in the line ablation rate in contrast to the basic structure after oxygen‐acetylene test. This achievement embodies the successful harmonization of lightweight properties with ablation resistance. Furthermore, based on the performance and microstructure of the char layer, a further analysis revealed the enhancement mechanism of ablative performance by the multilayer composite structure. It was found that the synergistic effect of the compact/porous structure of the char layer grants the bilayer structure thermal insulation material optimal ablative performance. This work provides strong support for improving the performance of SRMs.Highlights Insulation materials with multilayer composite structures are designed. The materials exhibit both lightweight and superior ablation resistance. Compact/porous char layers enhance material ablation performance.

Mechanically durable plant-based composite surface towards enhanced antifouling properties

The biofouling adhering to underwater facilities has a negative impact on the environment, energy, and economic development. However, conventional anti-adhesion organic silicon and organic fluorine materials often have poor adhesion properties and mechanical stability when combined with substrates. This work presents a novel strategy for preparing composite antifouling coatings that low surface energy plant-based carnauba wax (CW) covering through rough substrates and chemically bond with flexible polydimethylsiloxane (PDMS) oligomers or polymers. The CW coating adheres strongly to the substrate owing to the mobility of the liquated CW, which flows into the micro-nano structure of the substrate and solidifies on the solid surface. The polymerization reaction of (PDMS) oligomers compounded the coating, thereby creating a composite coating with superior lubricating and antifouling properties. This distinctive bonding process imbued the coating with exceptional characteristics, including remarkable mechanical stability in destructive tests as well as an impressive ability to repel fouling, such as protein attachment, bacterial adhesion, diatom deposition, and biofilm formation. This work systematically investigated the impact of the composition and structure of composite materials on their mechanical stability and resistance to fouling, and developed high-performance antifouling coatings in the real world.