Search

In this research, the role of B4C-reinforcing particles on the corrosion behaviour of Al5083/B4C nanocomposite has been investigated. Al/B4C nanocomposite powder with weight percentages of 3 and 7 of reinforcing phase was prepared by mechanical milling method. The resulting powder was initially hot-pressed and then hot-extruded. The microstructure of the sample was studied using scanning electron microscopy and their corrosion behaviour was studied using potentiodynamic polarization and scanning electrochemical impedance spectroscopy methods in different immersion time intervals. The results showed a uniform distribution of reinforcing particles and also the scattering of intermetallic particles at the surface of the samples. However, increasing the content of B4C particles in the composite samples enhances the cathodic and anodic reactions by increasing the content of intermetallic particles as cathodic sites on the surface, so that higher corrosion current density is observed in the composite samples with 7 wt% B4C. Finally, it was concluded that increasing the value of B4C decreases the corrosion resistance of the B4C-reinforced composite samples in sodium chloride solution, which makes it unsuitable in marine applications. [ABSTRACT FROM AUTHOR]

Adsorption has been reported to be optimal among oil spill cleanup methods due to its simplicity, low capital and operational cost, high removal efficiency and environmental friendliness. However, its continuous usage has been linked to generation of enormous waste, after oil spill cleanup, to which use of reusable oil sorbents has been proposed as a possible solution. Synthetic organic oil sorbents have high mechanical properties compared to other categories of oil sorbents, but they suffer low adsorptive capacities. To address this problem, among other nanoparticles, rGO have been infused in polymeric materials to produce composite oil sorbents characterized with high adsorptive capacities. In this research, surface modified rGO was infused in waste expanded polystyrene, to produce electrospun PS/FrGO composite sorbents by solution blending and electrospinning method. Adsorptive capacities of produced composites were evaluated in four oil samples. Functionalization of rGO was found to cause removal of residual oxygen containing functional groups such as hydroxyl (–OH), and resulted in more hydrophobic surface. Infusion of FrGO, in waste expanded polystyrene resulted into composites with increased surface area, from 71.50 m2/g for pure PS20 to 353.45 m2/g, 429.18 m2/g, 456.14 m2/g for PS20 infused with 1, 2 and 4wt% of FrGO. Increase in oil sorption capacities of the composite, observed in four oil samples corresponds to improved surface area. Produced composites show good recyclability in the four oil samples, at least up to the third sorption cycle. Highlights: Modification of Graphene oxide (GO) to reduced Graphene Oxide (rGO) rGO was functionalized and infused in Polystyrene (PS) to form PS/FrGO composite PS/FrGO composite was applied to oil–water mixture for oil adsorption Reusability of composites produced was evaluated. [ABSTRACT FROM AUTHOR]

Zinc chloride–activated carbon (AC) and nano zinc oxide/activated carbon composite (NZAC) as solid adsorbents were synthesized from date palm fronds (DPF) as a green material of activated carbon, while zinc oxide nanoparticles (NZ) were prepared in the presence of polyethylene glycol as capping agent. All the prepared solid adsorbents were investigated by several characterization techniques such as thermogravimetric analysis (TGA), nitrogen adsorption/desorption isotherm, Fourier transform infrared spectroscopy (FTIR), pH of point of zero charges (pHPZC), scanning electron microscopy (SEM), and transmission electron microscope (TEM). The NZAC sample had the highest total pore volume (0.960 cm3/g), specific surface area (2085.47 m2/g), and with pHPZC of 7.8. Adsorption of methylene blue was tested by Langmuir, Freundlich, and Temkin adsorption isotherms. NZAC had the highest Langmuir adsorption capacity (456.62 mg/g) at 40 °C with a dimensionless separation factor (RL) of 0.030. MB adsorption matched well with pseudo-second-order and Elovich kinetic models. The entropy, free energy, and heat changes for MB adsorption onto NZAC were found to be 0.0243 (kJ/mol. K), − 3.5589 (kJ/mol), and 3.561 (kJ/mol), respectively. Thermodynamic analysis demonstrated that the adsorption process of MB is favorable, spontaneous, physisorption, and endothermic. Desorption studies showed that HCl (0.01 mol/L) achieved the higher desorption percent (87%) compared with the other eluents. [ABSTRACT FROM AUTHOR]

Terephthalic acid (TPA) was recovered by alkaline hydrolysis of waste polyethylene terephthalate (PET) bottles. TPA recovered was used to prepare Sn-based catalyst by solvothermal method. For comparison, commercial TPA was also used to prepare Sn-based catalyst. The catalysts were used for the electrochemical reduction of CO2 to formate. Both the catalysts were found to possess nanoflake morphology, and were highly porous in nature with Brunauer–Emmett–Teller (BET) surface area of 211.4 and 239.4 m2/g for commercial and PET derived TPA-based Sn catalysts, respectively. The catalyst made from the waste PET bottles derived TPA was found to be more effective than the one obtained from the commercial TPA. The Faradaic efficiency obtained for the formation of formate was 68.4% at potential − 1.8 V (vs Ag/AgCl) and current density of 13.5 mA/cm2, when catalyst was synthesized using waste PET derived TPA. High activity of the electrocatalysts was attributed to higher capacitance, and lower resistance of the catalysts. [ABSTRACT FROM AUTHOR]

Six types of γ-polyglutamic acid (γ-PGA)/cold water-soluble starch (St) composite film models were constructed using molecular dynamics simulation, and their properties were investigated and compared with the corresponding experimental values. The compatibility between the composite film components was analyzed using the radial distribution function and mean square displacement (MSD). The hydrogen-bond number and bond energy were used to track the film-formation process. The mechanical property data of the films were extracted, and MSD was used to analyze the permeability of the film to carbon dioxide, oxygen, water vapor, and carbon-16 saturated fatty acids. Finally, the simulated values of mechanical properties and permeability were compared with the experimental values. The results demonstrated that γ-PGA is well compatible with St. The intramolecular and intermolecular hydrogen bonds of γ-PGA and St did not change considerably during the film-formation process. The simulated values of the mechanical properties exhibited a similar trend as the experimental values; however, in terms of permeability, a difference was observed between the initial values of the simulated design and actual material parameters, as well as the complexity of the experiment. [ABSTRACT FROM AUTHOR]

Herein, a study on the chitosan-amalgamated gold nanoparticles (AuNPs)- and silver nanoparticles (AgNPs)-based molecularly imprinted polymer (MIP) film and its application to recognize/remove ciprofloxacin (CIP) antibiotic in real samples is reported. The pomegranate peel at pH 8 is used for the reduction of silver nitrate solution to form AgNPs, whereas chitosan itself is used for the reduction of gold chloride solution to form AuNPs. The size of the synthesized AgNPs and AuNPs is in the range 30–45 and 45–50 nm, respectively, which is determined by dynamic light scattering (DLS). Further, the synthesized nanoparticles (NPs) are used to prepare MIP film. The molecularly tailored chitosan-based nanocomposite is used as a functional biopolymer to enhance the adsorption capacity and surface area of MIP film. The properties of synthesized chitosan-based AuNPs- and chitosan-based AgNPs-MIP composite (Chi@AuMIP and Chi@AgMIP) exhibited much higher adsorption capacity than non-imprinted polymer (NIP). The results revealed that the theoretical equilibrium constant (KL) and maximum adsorption capacity (Qmax) found by the Langmuir model are 12.2 and 20.48 mg g−1 for Chi@AuMIP and 18.31 and 34.13 mg g−1 for Chi@AgMIP, respectively. The recovery percentage of CIP for Chi@AuMIP and Chi@AgMIP is 98 and 80%, respectively. The selectivity experiment data suggest maximum adsorption capacity for targeted molecule (CIP) by the MIP as compared to analogs of template molecule. MIP showed relative potential selectivity and good recovery percentage for CIP in real samples as well. [ABSTRACT FROM AUTHOR]

Eggshell, a readily available natural material, possess remarkable properties that enhance the mechanical and tribological performance of composites, as evidenced by numerous studies. However, a scientometric analysis specifically examining the research landscape of eggshell-based composites has not been previously conducted. This study addresses this gap by employing a data processing, mining, analysis, presentation, and contemporary visualization approach to analyze bibliographic data on the effects of eggshell in composites. This analysis aims to inform researchers and guide future research directions in this promising field. Scopus data was utilized for the scientometric analysis, which encompassed publishing sources, leading authors, frequently used keywords, key publications, and the countries with the most significant contributions. The analysis revealed that “eggshell” is a prominent keyword within the field. Additionally, “Key Engineering Materials” emerged as a publication source with a high number of citations and articles. Notably, India was identified as the leading country in terms of research output. The graphical and quantitative representation of researchers and nations presented in this study facilitates knowledge sharing and fosters collaborative research efforts among academics. Furthermore, this study strengthens the evidence for eggshell potential to improve the mechanical and tribological properties of composites across diverse applications. However, it is crucial to acknowledge that the pre-treatment method and composite composition significantly influence the final material’s strength and durability.Article Highlights: Nature-derived materials, such as eggshell, hold immense promise for utilization as bio-ceramics in composites, paving the way for the development of environmentally friendly products. Numerous studies have explored the use of eggshell as a composite material to address environmental concerns. Eggshell exhibit unique characteristics that enable them to serve as replacements for conventional friction materials, thereby mitigating the generation of wear debris that poses detrimental environmental impacts. [ABSTRACT FROM AUTHOR]

Aluminium (Al) matrix composites are widely used in the automotive and aerospace sectors due to their low density, high specific strength, and excellent tribological performance. Although wear studies on Al matrix composites started approximately 40 years ago, they still continue to attract. This review reports the latest developments on the wear performance of up-to-date Al matrix composites. For this reason, the effect of different factors such as applied load, sliding speed, sliding distance, temperature, particle content, and particle size on tribological performance was investigated, considering the coefficient of friction and wear rate. Dominant wear mechanisms depending on wear parameters were also evaluated. Consequently, the review provides the challenges and future research directions in the tribology of Al matrix composites. [ABSTRACT FROM AUTHOR]

This study introduces the possibility of using polyaniline as a thermally conductive filler in the manufacturing process of composites using epoxy. Compared to conventional thermally conductive fillers, polyaniline is a material with a simple synthesis process and is cost-effective. In this experiment, among various types of polyaniline, polyaniline in the form of an emeraldine salt (ES) doped with protons and polyaniline in the form of a dedoped neutral emeraldine base (EB) were used as the thermally conductive filler. ES doped with protons show higher electrical and thermal conductivity than EB due to the conductive polymer characteristics in which the thermal conductivity increases as the electrical conductivity increases. We put both fillers into the widely commercially available diglycidyl ether of bisphenol A (DGEBA) epoxy composite, and analyzed the effect of the thermal conductivity of the filler increased by doping on the thermal conductivity of the composite, and analyzed the possibility of use as a thermally conductive filler. The epoxy resin without filler was measured to have the thermal conductivity of 0.21 W/m K, the thermal conductivity of the composite reinforced with EB filler was measured to be 0.27 W/m K, and the thermal conductivity of the composite reinforced with ES filler was measured to be 0.29 W/m K. The results confirmed that the input of polyaniline as a thermally conductive filler could improve the thermal conductivity of the composite, and also confirmed that the proton-doped ES filler showed higher thermal conductivity than the neutral EB filler. Through this study, we highlight the possibility that polyaniline can be used as a promising thermally conductive filler for various composite materials. [ABSTRACT FROM AUTHOR]

Cockle shell (CS) is a food-based solid waste. CS has no economic value and mostly dumped in landfills without prior treatment. This paper presents the results on the feasibility study of CS as a filler to produce thermoplastic composites. CS contains high amount of calcium carbonate. At present, precipitated calcium carbonate from limestone is used as filler in polymer industry. Thus, it is foreseen that CS could substitute the usage of limestone and indirectly preserve our natural limestone from destruction. CS [10–50 parts of thermoplastic polymer (pphr)] was used as filler to produce low-density polyethylene (LDPE) and LDPE/corn starch composites. Readings of Young modulus, thermal decomposition temperatures and crystallinity of all the composites were higher compared to pure LDPE. Tensile strength of the composite increased compared to pure LDPE at 10 pphr loading. Weight loss of the thermoplastic composites filled with CS in soil burial test indicates the potential of partial biodegradability of the composites after its service life. In future works, surface treatment of CS with suitable chemicals could be carried out to enhance the interaction between CS and LDPE matrix. [ABSTRACT FROM AUTHOR]

The results of applying self-propagating high-temperature synthesis (SHS) for fabricating high-temperature nickel alloys and composites based on titanium carbide (TiC) and nickel are reviewed. To reduce brittleness, it is proposed to replace the TiC phase by Ti3SiC2 titanium silicon carbide and apply the SHS process to fabricate the Ti3SiC2–Ni skeleton composite. Nickel, for infiltrating the Ti3SiC2 skeleton, is introduced in three variants: with the addition into the reaction mixture, in the form of a briquette arranged between two SHS charge briquettes, and similarly to the second variant, but with barrier paper layers between nickel and SHS charge briquettes. It is shown that, in all variants, the Ni melt prevents the formation of the titanium silicon carbide MAX phase, thus leading to its degradation. The introduction of Ni into the reaction mixture according to the first variant makes it possible to form a homogeneous composite material, the porosity of which decreased almost to zero with an increase in the Ni concentration to 50%. If the Ni briquette is arranged between two compacted SHS charge briquettes, it is possible to melt a relatively small amount of nickel (23–29% of the weight of samples of synthesized composites), which is insufficient to completely fill the porous layered Ti3SiC2 skeletons. When adding 20% Si into the Ni briquette, the infiltration depth increased; the degree of degradation of the MAX phase in the infiltration place decreased; and a more homogeneous composite consisting of the porous skeleton of TiC, TiSi2, and Ti3SiC2 phases partially filled with metallic nickel during the infiltration of the Ni(Si) melt is formed. [ABSTRACT FROM AUTHOR]

In this paper, NiO, Ni7S6, and different proportions of Ni7S6/NiO hybrids were synthesized by solvothermal method. The crystal structure, valence, and morphology of the prepared samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. Electrochemical performance of the prepared materials was tested by a series of electrochemical methods. And, the results showed that the electrochemical properties of Ni7S6/NiO composites were superior to those of Ni7S6 and NiO, which may be due to the synergistic effect between Ni7S6 and NiO. Furthermore, Ni7S6/NiO-30% shows the best electrochemical properties among the prepared samples. The electrochemical sensor based on the Ni7S6/NiO-30% has good electrocatalytic behavior for glucose oxidation, with a wide linear range from 0.09 to 3.12 mM, low detection limit (0.3 μM), long-term stability, and considerable reproducibility. Furthermore, it has good selectivity and could be used in human serum samples. Thus, this novel non-enzyme sensor has potential application in glucose detection. [ABSTRACT FROM AUTHOR]

In the present investigation, a new equivalent micromechanics method is proposed, and then, an analysis model has been developed to estimate the nonlinear coefficients of thermal expansion (CTEs) of three-phase composites. As Compared with previous analytical models, the innovative point of this paper is that the influence of the debonding surface thickness is investigated. It is noted that the parameters of thickness of debonding surface have a significant effect on both the longitudinal CTEs and transverse CTEs. The CTEs of composites are also very sensitive to the different inclusion aspect ratios. The constitutive equation curves for different variable parameters can describe the influence of debonding damage on thermal expansion coefficients (CTEs) of the composites. The new model provides a direct prediction of CTEs and can account for the effects of inclusion aspect ratio, volume fractions and thickness of debonding surface. [ABSTRACT FROM AUTHOR]

The paper considers the creep of a textile-reinforced thermoplastic composite with a glass filler under the action of a combined short-term cyclic and long-term static tensile loads at room temperature. The investigations were carried out on glass-fabric-reinforced polypropylene specimens, which were made by autoclave molding. The creep of the composite was experimentally investigated under a cyclic load at different amplitudes. The creep kernel has been calculated from experimental data according to the Boltzmann superposition principle. Other creep models of materials have been analyzed based on data from a review. The laws governing the short-term creep of polypropylene under the action of a static load have been determined. A behaviorial model of the composite under investigation under the considered conditions is proposed. Numerical calculations have been made with the aid of the proposed model using experimental results taken from other works, and a good agreement between them has been established. The peculiarities of the creep of textile-reinforced polypropylene under the considered conditions have been determined. The range of application of the model has been determined. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymer (CFRP) composites gained wide acceptance in aerospace, automotive and marine industries due to their superior properties. It became the major structural material that substitutes metals in many weight-critical components such as the new A350 and the B787 aircrafts, with composite content to exceed the 50%. Although CFRP structures are manufactured to near-net-shape, edge trimming, drilling, sawing, milling, and grinding operations are unavoidable. Being anisotropic, inhomogeneous and highly abrasive, their conventional machining is normally associated with delamination, fibers pull-out, inadequate surface quality, and tool wear. Other nontraditional processes which include abrasive water jet machining (AWJM), ultrasonic machining (USM), and electrodischarge machining (EDM) offer substitute to the conventional methods. Laser beam machining (LBM) is an emerging technology offering an excellent alternative for machining CFRP composites. This paper reviews the research work carried out in the area of LBM of CFRP materials. It reports the experimental and theoretical studies covering the process accuracy in terms kerf width, kerf depth and edge quality, and the thermal characteristics in terms of heat-affected zone (HAZ). Minimizing the kerf taper, increasing kerf depth, and eliminating the HAZ in the polymer matrix are considered the major obstacles of CFRP industrial applications. Methods of improving the machining productivity by reducing the machining time and increasing the material removal rate (MRR) and kerf depth are reviewed. Several mathematical and statistical modeling and optimization techniques have been critically examined. The concept of specific energy and its impact on HAZ and kerf width is introduced. The relationship between laser type and HAZ is discussed. The current work furthermore outlines the possible trends for future research. [ABSTRACT FROM AUTHOR]

In this paper, the effect of sliding speed on tribological properties of AA7075-Si3N4 composites has been investigated. The tribological testing was carried on a unidirectional pin on disc tribometer at three different sliding speeds (1 m/s, 4 m/s, and 7 m/s) at a constant load of 30 N. The wear loss increased with an increase in speed and coefficient of friction decreased with an increase in speed. The morphologies of the worn samples were investigated by SEM and it was observed that in case of unreinforced alloy and lower concentrations (2 wt% and 4 wt%) delamination was the dominant wear mechanism and, in case of higher Si3N4content (8 wt%) abrasive wear was the dominant wear mechanism. Heavy plastic deformation and deeper grooves were observed in case of higher speeds. Mechanically Mixed Layer (MML) formation was also confirmed by EDS. The developed material could serve various high speed sliding wear applications in automotive sector. [ABSTRACT FROM AUTHOR]

The paper analyzes how the antifriction composites produced from AK12MMgN silumin grinding waste with MoS2 solid lubricant additions acquire their structure and porosity. The materials are intended to perform in friction joints at elevated loads of 2.0–4.0 MPa and sliding velocities of 1.0−3.0 m/s in air. It is shown how the process developed for producing these materials influences their structure and tribotechnical properties. The distribution of MoS2 in the AK12MMgN-matrix composite, its role in the self-lubrication mechanism, and the distribution of MoS2 and chemical elements of the friction joint in the contact zone in the sliding friction conditions corresponding to actual operation of joints in a printing machine are studied. The solid lubricant is uniformly distributed over the friction surfaces and thus covers the entire friction zone in the friction process. The tribological films formed in the presence of a MoS2 solid lubricant promote high antifriction properties of the composite produced from silumin waste. These properties allow the operational conditions to be improved and extend the application of new wear-resistant materials produced from recycled materials in contact joints of printing machines. [ABSTRACT FROM AUTHOR]

During braking, a heat flow is generated by friction and heated the brake components, the heating causes thermal expansion in the disc and the pads and these expansions alternate the contact. This paper proposes a transient thermomechanical simulation of friction by the finite element method of disc/pads of a sport cars brake using ABAQUS. In this comparative study, three different ceramic composite materials (A359/SiC p20, Al6061/SiC, C/C-SiC) are used for the disc which is in friction with organic (C/C) lining bonded to steel back plates of the brake pads. This will allow us to emphasize the importance of the distribution and the variation of the temperature on the contact pressure and the stress field and the braking torque. [ABSTRACT FROM AUTHOR]

Abstract: The alloy coatings such as zinc-nickel are used to improve the lifetime of zinc sacrificial coatings. zinc-nickel alloy coating has a longer history than other zinc alloy coatings and is considered as the most corrosion resistive zinc alloy. One of the important properties of this type of coatings is the ductility properties of coated steel pieces; as after thermal treatment and shaping operations, the corrosion resistance is enhanced up to an optimal level. Because of such properties, this alloy is investigated in coating the pieces such as connecting bolts, brake system components, and fuel system. Resistance to heat, ultraviolet light, hydraulic fluids, and fuels are other characteristics of such coatings. The use of zinc-nickel alloy coatings is growing in the bolts and threaded parts industry. Since these coatings do not prevent galvanic corrosion in contact with aluminum, they are widely used in industries that deal with aluminum bodies. However, the zinc-nickel alloys are considered as the most expensive coatings. These alloys are coated both by acidic and alkaline baths that provide different coating properties. This paper reviews the studies conducted on zinc-nickel alloy coatings, analyzing baths and their properties, the effect of different parameters on electrodeposition, as well as Zn-Ni multilayer and composite coatings and their properties. [ABSTRACT FROM AUTHOR]

Abrasive jet machining is widely used for machining composites. Glass fibre composites find extensive use in aerospace industries, automobile sectors, medical fields and marine applications. Their usage in automated engineering industry needs a good surface finish. Glass fibre reinforced polymer composites are difficult to machine with conventional machining techniques. Hence, in this paper, abrasive jet machining of glass fibre reinforced polymer laminates was experimentally investigated for the various parameters in terms of average surface roughness (Ra). This work deals with making of holes on glass fiber reinforced polymer composite material using a newly designed nozzle with and without internal thread. The effect of jet pressure (P), stand-off distance (L), nozzle diameter (D), and abrasive size (S) on surface roughness (Ra) for two different nozzles was examined. The experimental result showed good surface finish on GFRP materials with the use of newly designed nozzle with an internal thread. [ABSTRACT FROM AUTHOR]

This paper presents the preparation of composite material and its application for the adsorption of crystal violet and Cr(VI) from aqueous solution onto acid-activated bentonite (AAB) and rarasaponin-bentonite-activated biochar from durian shells composite (RBAB). The influence of initial pH of the solution and the temperature of adsorption on the adsorbents adsorption performance was also studied. Langmuir and Freundlich models could represent the adsorption equilibria equally well. Thermodynamic parameters such as ∆G°, ∆H°, and ∆S° were evaluated based on the adsorption isotherms. The values of ∆G°, ∆H°, and ∆S° for crystal violet adsorption system demonstrate behavior contrary to the Cr(VI) adsorption system. Where crystal violet adsorption is preferred at high temperatures with qmax, value is 518.64 mg/L; while adsorption Cr(VI) is better at low temperature with qmax, value is 106.30 mg/L. Pseudo-first-order and pseudo-second-order kinetic models could represent the kinetic data well. [ABSTRACT FROM AUTHOR]

Sustainable manufacturing regulations are pushing manufacturing towards decreasing of manufacturing hazards including microparticles and ultrafine particles. Machining process such as milling produces dust that can be harmful for operators' health. The emission of this dust depends on workpiece materials (microstructure, mechanical properties) and machining conditions. The aim of this paper is to determine the effect of the microstructure and machining conditions on dust emission during dry milling of Al-20Mg2Si-2Cu metal matrix composite with addition of bismuth (Bi) and barium (Ba). Experiments were carried out using dry CNC milling by uncoated carbide tools. An aerodynamic particle sizer (APS) and a scanning mobility particle sizer (SMPS) were used to measure microparticles and ultrafine particles emission, respectively. It was found that the addition of 0.4 wt% Bi and 0.2 wt% Ba changed Mg2Si particle size and improved the hardness of composite. In addition, ultrafine particle number concentration, specific area concentration and mass concentration decreased with the addition of modifiers. It is also confirmed that cutting conditions and microstructure of workpieces have a direct effect on dust emission during the milling process. [ABSTRACT FROM AUTHOR]

The original form of Natural Rubber (NR) has limited usage despite its excellent elasticity and reversible deformability. Further improvement of its undesired properties, i.e. low hardness, durability and tear resistance will allow for application of NR on a broader scale. Traditional reinforcing materials such as carbon black have indicated improvement in NRbased composites. However, the increasing range of newly emerging applications comprising polymeric composites motivates researchers to focus on developing NR-based composites with better physical properties. Many nanoscale fillers have been widely researched to attain extraordinary properties in NR based products. Among the different nanostructures, carbon nanotubes (CNTs) have been widely examined for NR modification. Addition of a tiny amount of well-dispersed CNTs to NR allows for significant improvements in physical properties of NR. Preparing nanocomposites comprising CNTs and other types of fillers also demonstrates enhancement of NR properties. Besides improvements in mechanical properties, the presence of CNTs considerably improves other properties of NR, such as thermal stability as well as electrical and thermal conductivity. However, owing to interactions between individual CNTs as well as CNTs and other components (NR or other fillers), property improvement varies depending on the type of fillers and their ratio in NR. This review summarises the reported processing conditions and property improvements in NR reinforced with CNTs as a solefiller or with other additive fillers. This paper will help to better understand the status of research on developing an NR/CNT nanocomposite and discover challenges and obstacles that need to be resolved. [ABSTRACT FROM AUTHOR]

The paper deals with the homogenization of a boundary value problem for an inhomogeneous body with Cosserat properties, which is referred to as the original problem. The homogenization process is understood as a method for representing the solution of the original problem in terms of the solution of precisely the same problem for a body with homogeneous properties. The problem for a body with homogeneous properties is called the accompanying problem, and the body itself, the accompanying homogeneous body. As a rule, a constructive homogenization procedure includes the following three stages: at the first stage, the properties of the inhomogeneous body are used to find the properties of the accompanying homogeneous body (efficient properties); at the second stage, the boundary value problem is solved for the accompanying body; at the third stage, the solution of the accompanying problem is used to find the solution of the original problem. This approach was implemented in mechanics of composite materials constructed of numerous representative elements. A significant contribution to the development of mechanics of composites is due to Rabotnov [1-3] and his students. Recently, the homogenization method has been widely used to solve problems for composites of regular structure by expanding the solution of the original problem in a power series in a small geometric parameter equal to the ratio of the characteristic dimension of the periodicity cell to the characteristic dimension of the entire body. The papers by Bakhvalov [4-6] and Pobedrya [7] were the first in the field. At present, there are numerous monographs partially or completely dealing with the method of a small geometric parameter [8-14]. Isolated problems for inhomogeneous bodies with nonperiodic dependence of their properties on the coordinates were considered by many authors. Most of such papers published before 1973 are collected in two vast bibliographic indices [15, 16]. General methods were considered, and many specific problems of the theory of elasticity of continuously inhomogeneous bodies were solved in Lomakin's papers and his monograph [17]. The theory of torsion of inhomogeneous anisotropic rods was considered in [18]. In 1991, in his Doctoral dissertation, one of the authors of this paper proposed a version of the homogenization method based on an integral formula representing the solution of the original static problem of inhomogeneous elasticity via the solution of the accompanying problem [19, 20]. An integral formula for the dynamic problem of elasticity was published somewhat later [21]. This integral formula was used to develop a constructive method for the homogenization of the dynamic problem of inhomogeneous elasticity, which can be used in the case of both periodic and nonperiodic inhomogeneity of the properties [22]. The integral formula in the case of the Cosserat theory of elasticity was published in [23]. The present paper briefly presents constructive methods for homogenizing the problems of the Cosserat theory of elasticity based on the integral formula. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the addition of tungsten carbide on the behavior of Fe–WC system during the mechanical alloying (MA) process has been investigated. For this purpose, raw materials containing industrial ferrotungsten and carbon black with a bit of tungsten carbide powder were milled in a high energy ball mill, and sampling was done at different times. An XRD instrument was used for estimating the probable transformation of phases and properties in the milled sample. Microstructures of specimens were studied using electron microscopy. Results showed that MA even at high milling time could not transform raw materials to other materials in a system containing ferrotungsten and carbon black. In samples with primary tungsten carbide, this was synthesized gradually at a milling time of more than 75 h, and finally, the Fe–WC composite was produced as the final product. Crystalline sizes of the synthesized carbide were in nanometer order that was confirmed by transmission electron microscopy images. [ABSTRACT FROM PUBLISHER]

The most important role of footwear is to ensure safe, functional walking, and foot protection. For the proper functionality of not only the work shoes, the anti-slip behavior of the shoe under various conditions and environments plays an important role in the prevention of slips, trips, falls, and consequent injuries. This article is intended to review the current understanding of the frictional mechanisms between shoe outsoles and various counterfaces that impact the evaluation of outsole slipperiness. Current research focuses on the mechanisms driving outsole friction on different ground surfaces or the definition and description of parameters that influence outsole friction. Subsequently, the review discusses the effect of various surface contaminants on footwear friction. Lastly, challenges and outlooks in the field of footwear outsoles are briefly mentioned. [ABSTRACT FROM AUTHOR]

In this paper, a facile method has been developed to synthesize supported CoWO4 on the reduced graphene oxide (RGO) as high-performance anode material for Li-ion batteries. The composites with cuboid-like CoWO4 nanoparticles were prepared by directly adding graphene oxide into the precursor solution followed by a hydrothermal treatment. Different analytical methods like high-resolution TEM, XRD, TGA, and XPS characterizations were employed to illustrate structural information of the as-prepared CoWO4 and CoWO4/RGO composites. In addition, the Li-ion battery performance using the composites as anode materials was also discussed based on the detailed galvanostatic charge-discharge cycling tests. The result shows that the specific capacity of the as-prepared CoWO4/RGO composites can reach 533.3 mAh g−1 after 50 cycles at a current density of 100 mA g−1. During the whole cyclic process, the coulombic efficiency was maintained higher than 90%. Therefore, CoWO4, as an environment-friendly and cost-effective anode material, has promising potential for Li-ion batteries. [ABSTRACT FROM AUTHOR]

The paper describes the results of a study of composites with bentonite fillers and their dielectric properties as a function of the percentage of the dispersant and the alternating electric field frequency. It has been found that the pronounced dispersion of the dielectric parameters of the composites is caused by charge migration and localization at intrinsic point defects and at the interfaces with the sublattice of the dispersant. [ABSTRACT FROM AUTHOR]

In this communication we have compared the dielectric behavior of cobalt aluminate mullite (CAM) nanocomposite and cobalt aluminate mullite polymer (CAMP) nanocomposite with different molar concentration of Co +2 ions. The study of dielectric property of the CAM samples as well as that of the CAMP samples at room temperature shows that at all concentrations the dielectric constant is higher than pure mullite and there is a critical concentration of Co +2, where maximum enhancement of dielectric property occurs. This paper demonstrates that the loading of a conductive component into a highly insulating matrix is an effective way to fabricate composites with high permittivity as well as a charge storage material. We have designed a device using CAM as the electrode material and CAMP as the separator to compare it with a commercial Li-polymer ion mobile battery. We observed that the charge storage ability of the composite system is better than the commercial Li-polymer ion mobile battery. Our device persists for more than 24 h while the maximum voltage recorded by the device is 0.885 V, whereas the maximum voltage recorded by the conventional commercial Li-polymer ion mobile battery is 0.566 V. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a BiOCl/BiOF composite photocatalyst was obtained via simple mixture method. The as-synthesized sample was characterized by X-Ray Diffraction, Raman scattering, scanning electron microscopy, UV-Vis. diffuse reflectance measurements and electron spin resonance. A strong visible light absorption was observed with a narrowed bandgap compared with single BiOCl due to presence of oxygen vacancies. The photocatalytic activity of the product was evaluated through photocatalytic degradation of Methyl Orange (MO) under UV-Vis. light irradiation. The results show that the BiOCl/BiOF composite photocatalyst exhibits better photocatalytic activity in degrading MO than single BiOCl or single BiOF. The better photocatalytic properties can be attributed to the special band structure of the composite due to a good band matching between BiOF and oxygen vacancy states in BiOCl leading to an effective separation of electron-hole pairs. Moreover, the specific microstructure of the composite plays an active role in the good evaluated photocatalytic performances due to the intimate interfaces between the two parts.Graphical Abstract: [ABSTRACT FROM AUTHOR]

The paper presents an exact direct solution of a transverse plane bending problem of a laminated cantilever beam of small width under the action of a uniformly distributed load under the absolutely hard contact between the layers. The solution has been constructed with the aid of linear elasticity theory equations: to take into account the heterogeneous structure of the laminated beam, piecewise constant functions of elastic characteristics, which have been described analytically by means of shifted Heaviside functions, have been introduced into the Hooke's law relationships. During the solution of problem, the normal stresses were expressed from static equations in terms of an unknown function of tangential stress distribution over the cross-section height. The use of the obtained expressions in the Hooke's law relationships and Cauchy equations for linear strains made it possible to establish relationships between displacements and tangential stresses. The Cauchy equation that remained for angle strains gave a defining integro-differential equation, from which differential equations for the unknown tangential stress function and for all unknown integration functions have been derived. The solution of the derived equations is possible for the entire packet of layers without considering an individual layer, the final relations for stresses, strains and displacements describing the stress-strain state of the entire packet of composite beam layers. The constructed solution satisfies the boundary conditions and the conditions of the absolutely hard contact of the layers and is exact if the load distribution corresponds to the determined stress distribution. Using this solution, we have carried out a theoretical study of the stress-strain state of a three-layer beam. The obtained relation allow one to predict the strength and stiffness of multilayer structural composite elements and to construct application solutions for other elastic bending problems of laminated beams. [ABSTRACT FROM AUTHOR]

This paper focuses on the development of an advance numerical model specifically for simulating low velocity impact events and related stiffness reduction on composite structures. The model is suitable for low cost thick composite structures like wind turbine blade and maritime vessels. The model consist of a combination of inter and intra laminar models. The intra-laminar model present a combination of Puck and Hashin failure theories for the evaluation of the fibre and matrix failure. The inter-laminar damage is instead simulated by Cohesive Zone Method based on energy approach. Basic material properties, easily measurable according to standardized tests, are required. The model has been used to simulate impact and compression after impact tests. Experimental tests have been carried out on thick E-Glass/ Epoxy composite commonly used in the wind turbine industry. The clustering effect as well as the consequence of the impact energy have been experimentally tested. The accuracy of numerical model has been verified against experimental data showing a very good accuracy of the model. [ABSTRACT FROM AUTHOR]

This paper proposes a optimization method that is capable of simultaneous design of multiple layers in a composite laminate with respect to multiple objective functions. The optimization process obtains a continuous orientation of an orthotropic material for each layer of the laminate. Each layer by itself is a single design domain, which allows multiple domains to be stacked in various orientations. Multiple optimization objectives are considered resulting in layers that perform different functions. The layers are modeled within a three-dimensional structure and by discretizing the structure using three-dimensional elements, the interaction between individual layers can be modeled. This also allows the optimization method to obtain a three-dimensional orientation vector. In this study, the individual layers are assumed to be thin, limiting the orientation vector to the mid-plane of the layer. The optimization model is tested on a two-layer laminate in which one layer is optimized for thermal control by directing heat toward specified sections while shielding other sections and the second layer is optimized to reduce the total deformation of the laminate structure that results from the thermal load. The results of simultaneous optimization for both layers are shown for several different configurations of boundary conditions. [ABSTRACT FROM AUTHOR]

Development of affordable sorbents for solid phase extraction (SPE) in petroleum fingerprinting analysis is crucial in petroleum and petrochemical industries due to energy demand. In this paper, composite fibre based on expanded polystyrene and zeolite was nanostructured to nanoporous fibre with Type II + IV classification and superhydrophobic-superoleophilic properties. The potential of this composite fibre as SPE sorbent in petroleum fingerprinting was investigated and its efficiency was compared with commercial sorbents [alumina, silica and alumina/silica (hybrid)] cartridges. The chromatograms showed that the packed electrospun composite fibre demonstrated excellent cleaning and enrichment properties for SPE applications relative to the hybrid cartridges. This presents a novel re-use pathway for expanded polystyrene, promotes fast analysis and cost reduction in petroleum fingerprinting. [ABSTRACT FROM AUTHOR]

Functionally graded composite (FGC) materials are categorized as advanced materials that display different thermal and mechanical responses compared with well-known composites, such as carbon fiber or glass fiber-reinforced composites. This paper presents the experimental results for the drilling of three materials, namely glass/epoxy, carbon/epoxy, and FGC material. FGC was compared with carbon and glass/epoxy composites in terms of thrust force, delamination factor, diameter of hole, and roundness during drilling. This study illustrated that the drilling performance of FGC is considerably more complicated than that of more common composite materials, such as glass/epoxy and carbon/epoxy. Delamination factor at the exit of hole during drilling of FGC was mainly affected by the material placed at the exit of the hole. The proposed cutting parameters and drill geometries to minimize the occurrence of delamination during drilling of carbon/epoxy and glass/epoxy apparently does not meet the expectation in drilling FGC. [ABSTRACT FROM AUTHOR]

Natural rubber (NR) and regenerated cellulose (RC) are valuable natural polymers, which are promising materials for a green future. They can be combined to fabricate a biocomposite, but incompatibility between them can result in undesirable properties. The objective of this work is to assess the compatibility between deproteinized NR-grafted methyl methacrylate (MMA) and RC in their composite fabricated by co-precipitation. Graft copolymerization of MMA onto deproteinized NR was carried out in the latex stage using tert-butyl hydroperoxide and tetraethylenepentamine as radical initiators at 30 °C. The composites were prepared from grafted NR latex and cellulose solution in urea/NaOH/water by co-precipitation method, followed by hot pressing. The chemical and crystal structures of two phases in the composites were characterized by attenuated total refection Fourier transform infrared radiation, proton nuclear magnetic resonance and X-ray diffraction. The improvement in thermal stability of the composite has been demonstrated by thermal gravimetric analysis. A reduction in RC phase size and a smoother interface of the MMA-grafted composites compared to ungrafted samples were observed via scanning electron microscopy. Differential scanning calorimetry showed glass transitions of the composites increased steadily with increasing RC contents, from − 63.47 to − 63.2, − 63.07 and − 62.82 °C at respective 0, 10, 20 and 30% RC. These results indicated that enhanced compatibility between NR and RC has been obtained after modifying NR by graft-copolymerization method. [ABSTRACT FROM AUTHOR]

To address the global environmental pollution problems, the application of biodegradable agricultural waste as a reinforcing material in the development of composite materials is one of the prominent solutions for sustainable development. Following that in the present investigation, a hybrid epoxy–based composite is fabricated using banana and glass fibers as reinforcing materials for lightweight structural applications. The main purpose of this research article is to utilize banana fiber (a biodegradable agricultural waste) as a reinforcing material in composite fabrication because of its low cost, non-abrasive, and eco-friendly nature. Herein, the fabricated composite material was characterized by various tests such as tensile, flexural, hardness, impact, thermal conductivity, and scanning electron microscopy. The effects of volume fraction and sequence of banana and glass fiber layers on mechanical properties such as tensile strength, hardness, flexural, and impact strengths were also investigated. Our results showed that for sample with alternating layer of banana and glass fibers and 1 wt.% charcoal, the epoxy-based composite exhibited the highest tensile, flexural and impact strengths of about 80.9 N/mm2, 145.4 N/mm2, and 3.5 kJ/m2, respectively. The same sample also reported the highest hardness of 56 VH. Furthermore, with the addition of banana fibers, the thermal conductivity of the laminates also increased. This enhancement in the mechanical and thermal properties with amalgamation of biodegradable banana fiber, strong glass fiber and water-resistant epoxy resin may help in manufacturing of lightweight composite domains for automobile and structural applications. [ABSTRACT FROM AUTHOR]

In recent decades, the greatest challenge facing the world has been protecting the environment from various forms of pollution. Water pollution is one of the most crucial environmental problems threatening living organisms' lives and human health. Mostly anthropogenic, it undoubtedly originates from diverse sources, including agricultural, domestic, and industrial activities. Therefore, adopting sustainable and environmentally friendly practices constitutes an ideal solution for purifying contaminated water to be further used in industrial activities and so on. The valorization of lignocellulosic biomass for the production and conception of value-added products is an attractive and environmentally friendly way of preserving the environment. Lignocellulosic biomass, such as crops, agricultural wastes, forest residues, etc., is a sustainable and plentiful resource that can be valorized and used as robust material for eliminating different pollutants from sewage, including organic pollutants, heavy metals, inorganic compounds, and microorganisms. Indeed, the valorization of biomass wastes is among the most intelligent strategies. It is like killing two birds with one stone: reducing the quantity of biomass waste and benefiting from its physicochemical properties. Feedstocks are rich in cellulose, hemicellulose, and lignin, which have already been proven efficiency in removing persistent pollutants. Moreover, it can undergo physical, chemical, and thermal to prepare cellulose nanocrystals and biochar with high removal ability. The current review discusses the exploitation of lignocellulosic biomass to produce composite materials in the applications of wastewater purification, especially for the removal of different persistent organic and inorganic contaminants. It highlights the recent research studies and the mechanisms involved in eliminating pollutants using lignocellulosic-based materials. [ABSTRACT FROM AUTHOR]

Background: It has been noticed that failure of composite resin restorations can be attributed to either of the two following causes: fracture or secondary caries. For that reason, it is mandatory to formulate a restorative material with antibacterial effect. An octenidine dihydrochloride (OCT) has been assessed as an alternative to antimicrobial material, such as chlorhexidine due to their higher microbicidal effect and less cytotoxicity. Objective: Current study aimed to add different concentrations of octenidine dihydrochloride into experimental flowable resin composite and evaluate its antibacterial activity over different periods of time to provide the manufacturers with more precise information. Methods: A flowable resin composite material mix was formulated. Octenidine dihydrochloride antibacterial material was then added separately to the formulated mix at 1% wt. and 1.5% wt. concentration, respectively. Antibacterial activity was assessed against Streptococcus mutans using agar diffusion test and compared to a commercial resin composite. Results: It showed that by increasing the percentage of incorporated octenidine dihydrochloride (1% and 1.5%), respectively, the antibacterial efficacy against the Streptococcus mutans increased. Results of this study also showed the time had a significant decrease in the antibacterial effect. Conclusions: It can be concluded that by the incorporation of octenidine dihydrochloride (1% and 1.5%), respectively, the antibacterial efficacy against the Streptococcus mutans increased. Time had a significant decrease in the antibacterial effect of OCT. [ABSTRACT FROM AUTHOR]

This study explores the repurposing of waste glass optical fibers (SiO2 fibers) by using them as toughening agents for silicon. The poor fracture toughness of silicon has precluded its development as a structural material and reinforcing it with a second phase such as glass fiber is a potential route for enhancing its toughness. In this work, the focus is checking the extent of toughening brought about by the introduction of SiO2 fibers in the silicon matrix and understanding the reasons for the same. A composite of 79 wt.% silicon and 21 wt.% SiO2 fiber was synthesized by spark plasma sintering at 1473 K at an applied pressure of 75 MPa. The spark plasma sintered composite possessed a relative density of 99%. The silicon matrix and SiO2 fiber reinforcement exhibited an average hardness of 12 GPa & 7 GPa respectively. The indentation fracture toughness of the composite was observed to be 1.55 MPa.m1/2 which is ~ 8% higher than the indentation fracture toughness of nominally pure silicon. The SiO2 fibers were unable to provide sufficient crack deflection or crack blunting and consequently, the enhancement in toughness was marginal. [ABSTRACT FROM AUTHOR]

Glass Fiber Reinforced Polymer (GFRP) is commonly used in outdoor applications that expose it to environmental conditions capable of degrading its properties, notably ultraviolet (UV) radiation. In this study, we subjected GFRP to UV radiation for a duration of up to 180 days in an accelerated aging chamber. The composites underwent mechanical testing through tensile and flexural evaluations, while chemical and physical changes in the composite were assessed using Fourier-Transform Infrared Spectroscopy, Thermogravimetric analysis, and optical microscopy. Tensile tests revealed a noticeable reduction in GFRP strength after just one month of UV exposure, with a decrease of 18.7% observed at 90 days of exposure. In contrast, the behavior of the composite under flexural testing showed an initial improvement in strength after 30 days of UV exposure, with a significant increase of 54.1%. With longer exposure times, flexural strength gradually decreased but remained 18.9% higher than the strength of the unaged composite after 180 days of UV exposure. Other characterizations indicated material degradation, marked by phenomena such as photo-oxidation, composite yellowing, and the appearance of microcracks on the surface. These factors collectively contribute to the reduction in composite strength. Despite the visible degradation, the aged composite may exhibit improvements attributed to post-curing. However, over more extended periods, it may experience a decline in mechanical properties. Consequently, longer degradation times may unveil a behavior pattern distinct from what is observed during shorter periods, contingent upon the specific mechanical load under consideration. [ABSTRACT FROM AUTHOR]

Global economic development and efforts to enhance overall quality of life yielded growth in the construction and building sector, increasing not only the demand for materials but also waste generation. Its efficient management should take full advantage of the exceptional properties of building materials. The presented work is the first reported study on possibly using waste rigid polyurethane (PUR) foam, commonly applied as thermal insulation, as particle-shaped low-density filler for manufacturing hybrid epoxy-basalt composites. It investigated the potential management of waste PUR foam by applying it as a functional filler to hybridize epoxy-basalt composites. Herein, 1, 2, 5, and 10 wt% PUR powder were introduced into the thermoset-based composites prepared using the vacuum bag method. A comprehensive analysis of mechanical and thermomechanical properties correlated with changes in the composite structure revealed the beneficial aspects of the waste filler addition associated with increased heat deflection temperature and mechanical damping ability. Introducing micrometric domains of the waste filler changed the composites' fracture character. It enabled maintaining the impact strength of composites containing up to 5 wt% of PUR powder at the level of unfilled epoxy resin. However, despite that, the incorporation of PUR powder unfavorably affected tensile and flexural performance, yielding a significant drop in moduli and strength. [ABSTRACT FROM AUTHOR]

Impedance pump is defined as a type of valveless pumping mechanism, where an elastic tube is joined with a tube of different impedance, a periodic asymmetrical compression on part of the elastic tube will produce a unidirectional flow. Numerical and experimental studies had been conducted in the past, but little experimental work was found to exploit the principle of multi-stage impedance pumping for fluid transportation. This paper concentrates on the fluid behavior for an open-loop two-stage system experimentally. The aim of this work is to have an insight on the deliverable head and pumping rate of an open-loop two-stage impedance pumping system. This paper generally investigates the effect of different parameters towards the generation of unidirectional flows and composite flow of two opposite directions. Results obtained are of significant values. [ABSTRACT FROM AUTHOR]

This paper is a continuation of Survey I [], where the historical background and general remarks on the problem formulation and solution methods were outlined and results related to plane-strain problems were reviewed. In the present paper, a review of axisymmetric and 3D buckling delamination problems is presented. [ABSTRACT FROM AUTHOR]

The paper presents an experimental verification for calculating coupled stiffness matrix in complex curvature composite structure. The results of the analytical procedure using Variational Asymptotic Beam Sectional Analysis also indicate that the calculation of 2-D, beam, cross-sectional properties can then be incorporated into and 1-D beam analysis expressed coupled stiffness matrix. This paper presents the 2-D cross-sectional analysis of active anisotropic beams. Comparison between the analytical and experimental results shows that the proposed analytical procedure can provide an accurate and efficient prediction of the both deflection and flexural stiffness of multilayer composite slender structure. Verified comparison results can be used to efficiently design accurate complex slender structure properties for preliminary design and optimization. [ABSTRACT FROM AUTHOR]

The paper examines the wear mechanisms of the VT-3 titanium alloy and TBKhN composite in fretting corrosion conditions. It is shown that the oxide film formed on the titanium alloy during friction fails and further wear occurs on the juvenile surface. This leads to seizure and removal of the material from the surface, indicating that adhesive wear prevails in friction of the titanium alloy. The TBKhN40 composite is characterized by oxidative wear. The oxide film with grain-oriented fine structure forms in the friction process through selective oxidation of refractory and metal components. [ABSTRACT FROM AUTHOR]

Traditionally, hard or high-stiffness materials are used to achieve morphing but only with limited magnitudes of deformation. Soft and low-stiffness materials are required to implement soft morphing with large deformations. In this paper, a novel concept for soft morphing structures that makes use of smart soft composites (SSC) is introduced. These materials have the following characteristics: 1) Large deformations from smart actuators and soft anisotropic materials embedded in a soft matrix material, 2) Utilization of the coupling effect for in-plane/bending/twisting deformations of the morphing structure to achieve complex morphed shapes, 3) Semi-automated three-dimensional (3D) fabrication via 3D printing processes. Classical lamination theory is used to express in-plane deformation, out-of-plane deformation, and twisting and coupling of these deformations. 3D-printed-scaffold and/or weaving methods can be used to fabricate anisotropic materials for SSCs. An integrated SSC in a cantilever shape is fabricated using SMA (Shape memory alloy)/ABS/PDMS and tested as an example to show large deformation with bend/twist coupling effect. [ABSTRACT FROM AUTHOR]

Centrifugal force acting on a rotating disk induces in-plane loads in the radial and circumferential directions. An application of fiber-reinforced composite materials to a rotating disk can satisfy the demand for increasing its rotating speed. However, previous researches have been confined to single lamina disks. In this paper, a stress analysis of rotating disks made of multidirectional laminates is performed. The Tsai-Wu failure criterion is applied to the strength analysis of the rotating laminate disks, from which the maximum allowable speeds are obtained. The cross-ply ratios providing the maximum allowable speeds are obtained for the glass/epoxy and carbon/epoxy cross-ply laminate disks with CD geometry. [ABSTRACT FROM AUTHOR]

This paper presents a method to optimize the topology of structures under multiple load cases with stress constraints. Fiber-reinforced orthotropic composite is employed as the material model to simulate the constitutive relation of truss-like continua. The fiber densities and orientations at the nodes are taken as design variables. First, for each load case, the fiber orientations are aligned with the orientations of principal stress and the fiber densities are adjusted according to the strains along the fiber orientations. Then, to optimize the structure, the fiber densities and orientations under multiple load cases are determined by constraining its elastic matrix to approach the elastic matrix of the optimum structures defined for each single load case. Finally the member distribution in the optimal structure is suggested by the continuous lines formed according to the fiber densities and orientations. Several examples are presented to demonstrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]