Composite filaments are getting increased attention in additive manufacturing (AM). More and better solutions for filament production are needed to assist researchers in discovering new materials capable of producing AM-made high-performance parts. This article presents a method for producing composite filament, including an open-source, low-cost automatic composite feeder designed to increase the accuracy and quality of the filament. The feeder includes a fibre screw designed through an iterative prototyping process to accurately control the filament's fibre percentage while reducing lumps' occurrence in a single step. An experiment evaluating the quality of filament made of Polylactic Acid (PLA) and carbon fibre (CF) tested the use of the feeder compared to manual mixing. Filament with a nominal diameter of 2.85mm with 4.5%, 7.9%, 11.2% and 14.5% CF was made. The results suggest that the composite feeder improved the filament quality. The filament diameter RMSE value was reduced from 0.08 to 0.06 and 0.15 to 0.13 for both 4.5% and 11.2%, respectively. The article concludes that the feeder design may help researchers develop and discover new materials while improving the quality of the filament.

The literature lacks methodologies to make supply chains of composite materials circular. The proposed approach aims to transform scraps and off-specification products into secondary raw materials. Its novelty is to find innovative applications, instead of re-introducing scraps in the loop they come from. The case study investigates how scraps can be re-worked and re-used as raw material. First, the processes are analyzed; some components are then re-designed to be made of the discarded scraps (composites material). Results reveal that the symbiosis can ensure green, high performing products.

In this paper, we show that the permeability of a porous material (Tartar (1980)) and that of a bubbly fluid (Lipton and Avellaneda. Proc. R. Soc. Edinburgh Sect. A: Math. 114 (1990), 71–79) are limiting cases of the complexified version of the two-fluid models posed in Lipton and Avellaneda (Proc. R. Soc. Edinburgh Sect. A: Math. 114 (1990), 71–79). We assume the viscosity of the inclusion fluid is $z\mu _1$ and the viscosity of the hosting fluid is $\mu _1\in \mathbb {R}^{+}$, $z\in \mathbb {C}$. The proof is carried out by the construction of solutions for large $|z|$ and small $|z|$ with an iteration process similar to the one used in Bruno and Leo (Arch. Ration. Mech. Anal. 121 (1993), 303–338) and Golden and Papanicolaou (Commun. Math. Phys. 90 (1983), 473–491) and the analytic continuation. Moreover, we also show that for a fixed microstructure, the permeabilities of these three cases share the same integral representation formula (3.17) with different values of contrast parameter $s:=1/(z-1)$, as long as $s$ is outside the interval $\left [-\frac {2E_2^{2}}{1+2E_2^{2}},-\frac {1}{1+2E_1^{2}}\right ]$, where the positive constants $E_1$ and $E_2$ are the extension constants that depend only on the geometry of the periodic pore space of the material.

Digital manufacturing was employed to 3D print continuous Carbon, Glass and Kevlar fibre reinforced composites in Unidirectional (UD) [0°], Off-axis ±45° and Cross-ply [0°/90°] layup sequence. These 3D printed composites were subjected to quasi-static, in-plane tension and out-of-plane (compression and shear) loading. The tensile strength of 3D printed Carbon, Glass and Kevlar UD laminates was significantly lower than that of 3D printing filaments used to manufacture them. The type of fibre (brittle/ductile) reinforcement was found to be governing the shear yield strength of 3D printed composites despite having the same Nylon matrix in all the composites. Out-of-plane compressive strength of the 3D printed Carbon and Glass fibre reinforced composites was independent of specimen size. Contrary to that, Kevlar fibre composites showed a pronounced size effect upon their out-of-plane compressive strength. A combination of X-ray tomography and pressure film measurements revealed that the fibres in 3D printed composites failed by ‘indirect tension’ mechanism which governed their out-of-plane compressive strength. To gain further insights on the experimental observations, Finite Element (FE) simulations were carried out using a pressure-dependent crystal plasticity framework, in conjunction with an analytical model based on shear-lag approach. Both FE and analytical model accurately predicted the out-of-plane compressive strength of all (Carbon, Glass and Kevlar fibre reinforced) 3D printed composites.

The composites were synthesized by the reaction of Bi(NO3)3·5H2O, KI, and MoS2 and were prepared with different molar ratios of Bi/Mo (1:5, 1:2, 1:1, and 4:1) by altering the amount of bismuth nitrate pentahydrate. The phase composition and chemical bonds of the composites were characterized via X-ray diffraction and FT-IR, and the morphologies of the samples were characterized via scanning electron microscopy. With the increase of lanthanum source, the lamellar structure of the sample surface became more and more obvious. The results showed that the phase composition of the composites with different ratios of Bi/Mo was different. When the Bi/Mo reached 4:1, the composite material was Bi2MoO6/BiOI. The heterojunction structure formed between Bi2MoO6 and BiOI effectively promotes the separation of photogenerated electrons and holes and improved the photocatalytic activity. Therefore, the effect of the composites on the degradation of RhB was better than pure BiOI under the irradiation of a 350-W xenon lamp.

Ni2P/ZnS and Ni2P/CdS core/shell composites were synthesized using a simple two-step route at a low temperature. We used X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, and so on to characterize their composition, structure, and morphology. The characterized results show that Ni2P/ZnS and Ni2P/CdS core/shell composites consist of Ni2P microsphere core and ZnS (or CdS) nanostructure shell, and CdS nanorods and ZnS nanoparticles are deposited on the surface of Ni2P microspheres, respectively. Then choosing methylene blue (MB) as a typical organic dye, the photocatalytic degradation activities of Ni2P/ZnS and Ni2P/CdS are investigated, which exhibit a good photocatalytic activity. When the concentration of MB solution is 1 × 10−5 mol/L and the mass of the added photocatalyst is 0.05 g, it is found that two composites have enhanced photocatalytic degradation ratios (89 and 78%) compared to that of Ni2P microsphere (65%), which might be due to the effective separation of photogenerated electron-hole pairs.

The imperfection sensitivity of cylindrical panels under compression loading is shown to be not only reduced but effectively eliminated using stiffness tailoring techniques. Shells are designed with variable angle-tow (VAT) laminae, giving their laminates variable-stiffness properties over the surface co-ordinates. By employing an asymptotic model of the non-linear shell behaviour and a genetic algorithm, the post-buckling stability was maximised with respect to the VAT design variables. Results for optimised straight-fibre and VAT shells are presented in comparison with quasi-isotropic designs. In the straight-fibre case, small improvements in the post-buckling stability are shown to be possible but at the expense of the buckling load. In the VAT case, on the other hand, considerable improvements in the post-buckling stability are obtained and drops in axial stiffness and load associated with buckling are reduced to negligible levels. The improvements are shown to be a result of a benign membrane stress distribution prior to buckling and a localisation of the buckling mode. The asymptotic results are compared with non-linear finite-element analyses and are found to be in good agreement. Potential future multi-objective optimisation studies are discussed.

This paper presents a dynamic formulation of the boundary element method for stress and failure criterion analyses of anisotropic thin plates. The elastostatic fundamental solutions are used in the formulations and inertia terms are treated as body forces. The radial integration method (RIM) is used to obtain a boundary element formulationithout any domain integral for general anisotropic plate problems. In the RIM, the augmented thin plate spline is used as the approximation function. A formulation for transient analysis is implemented. The time integration is carried out using the Houbolt method. Integral equations for the second derivatives of deflection are developed and all derivatives of fundamental solutions are computed analytically. Only the boundary is discretized in the formulation. Numerical results show good agreement with results available in literature as well as finite element results.

An alternative focused ion beam preparation method is used for sampling historical photographs containing metallic nanoparticles in a polymer matrix. We use the preparation steps of classical ultra-microtomy with an alternative final sectioning with a focused ion beam. Transmission electron microscopy techniques show that the lamella has a uniform thickness, which is an important factor for analytical transmission electron microscopy. Furthermore, the method maintains the spatial distribution of nanoparticles in the soft matrix. The results are compared with traditional preparation techniques such as ultra-microtomy and classical focused ion beam milling.

Au nanoparticles (Au NPs) have attracted much interest owing to their unique optical properties. In this paper, a facile process has been successfully developed to synthesize the SiO2/Au hybrid microspheres with a diameter of 200 nm via the galvanic replacement of SiO2/Ag hybrid microspheres and chlorauric acid (HAuCl4) solution. The as-prepared products were investigated by x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM, JEOL-6700F), and transmission electron microscopy (TEM, JEOL 3010), respectively. As expected, the as-prepared SiO2/Au hybrid microspheres show strong chemical stability and superior catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The SiO2/Au hybrid microspheres would be found widely used in wastewater treatment, catalytic reaction, bacteriostatic and bactericidal applications.

Cette étude expérimentale présente de nouveaux matériaux composites développés récemmentpour le brasage de pièces en cuivre. Il s’agit de compositions à base d’agarose quipeuvent être mises en forme par moulage par injection de poudres. Cette facilité de miseen œuvre ouvre comme possibilité d’application la fabrication de préformes de brasage deformes complexes. Deux exemples d’utilisations sont présentés, l’un porte sur le brasagetendre et l’autre concerne le brasage fort. Les brasures finales obtenues permettentd’obtenir une résistance mécanique et une qualité métallurgique similaires à cellesobtenues à partir des matériaux conventionnels (bases SnPb ou CuP) utilisés pour lebrasage manuel de tubes en cuivre.

Under the COMPASS (condensed-phase optimized molecular potentials for atomistic simulation studies) force field, the molecular dynamics (MD) simulation was applied to first-to-third generation nanosize amine-based and butanediamine-based graphite/dendrimers composites. In this paper, we briefly introduced the constructive process of the composite system by means of MD simulation. The stability and mechanism of six intercalation composites were studied with microcosmic figure and variational energy under the invariable NVT ensemble. The energy variety was analyzed using the radial distribution function. The results indicate that the bulk of the dendrimer is small, the graphite layer is easy to bend and its systematic total energy is higher, which lead to the instability of the composite system. Therefore, the 3G dendrimer is the most stable system.

Le but est d’innover dans le domaine des liaisons au sol en remplaçant une traverse d’un essieu arrière en acier à haute limite élastique par une traverse en matériaux composites : Fibre de verre et Epoxy; tout en conservant les mêmes fonctions qui sont : assurer une rigidité de torsion, lier et maintenir en position les bras de suspension, résister aux sollicitations mécaniques du cahier des charges (nid de poule, choc trottoir, ...), reprendre les points de fixation du bras de suspension. Cette étude tient compte de la problématique de la grande série : minimiser le nombre de pièces, géométrie simple, procédé de fabrication simple avec des cadences élevées, facilité de montage. La démarche employée est la suivante : étape de présélection et intégration des profilés dans le modèle numérique, choix de l’empilement du composite et optimisation, choix d’une solution, conception des interfaces, réalisation d’un prototype. Le gain de masse est significatif puisque la traverse composite avec fixation ne pèse que 3,9 kg à comparer avec les 12,4 kg de la traverse initiale.

Multicomponent composite materials comprised of a dispersed phase suspended in a matrix material are important in a wide variety of scientific and engineering applications including electronic encapsulation, functionally graded materials, and fiber-reinforced structural components among others. Modelling of this class of composites is typically performed using an effective property approach. This approach presumes that the characteristic dimension of the dispersed phase elements is small in comparison to the characteristic length scale of the physical problem under consideration. However, it is not possible to predict a third effective elastic property based on two independent effective elastic properties as it is for homogeneous elastic isotropic materials. Therefore, a macroscale simulation based on an effective Young's modulus and Poisson ratio may yield poor results for a material subjected to shear loading since there is a potentially incorrect presumed effective shear modulus for the simulation. In the current research, boundary element simulations are performed for mesoscopic samples of composite materials to determine effective bulk moduli, shear moduli, Young's moduli, and Poisson ratios. From these analyses, limitations in the effective property approach can be examined.

Optical-fiber sensors based on fiber Bragg gratings (FBGs) provide accurate, nonintrusive, and reliable remote measurements of temperature, strain, and pressure, and they are immune to electromagnetic interference. FBGs are extensively used in telecommunications, and their manufacture is now cost-effective. As sensors, FBGs find many industrial applications in composite structures used in the civil engineering, aeronautics, train transportation, space, and naval sectors. Tiny FBG sensors embedded in a composite material can provide in situ information about polymer curing (strain, temperature, refractive index) in an elegant and nonintrusive way. Great improvements in composite manufacturing processes such as resin transfer molding (RTM) and resin film infusion (RFI) have been obtained through the use of these sensors. They can also be used in monitoring the “health” of a composite structure and in impact detection to evaluate, for example, the airworthiness of aircraft. Finally, FBGs may be used in instrumentation as composite extensometers or strain rosettes, primarily in civil engineering applications.

This paper is part of a larger project initiated with [2]. The final aim of the present paper is to give bounds for the homogenized (or effective) conductivity in two dimensional linear conductivity. The main focus is therefore the periodic setting. We prove new variational principles that are shown to be of interest in finding bounds on the homogenized conductivity. Our results unify previous approaches by the second author and make transparent the central role of quasiconformal mappings in all the two dimensional G-closure problems in conductivity.

A one-dimensional packing approach is used to obtain limiting results for inter-crack distances after multiple fracture of a long brittle-matrix composite with continuous aligned fibres. The results may also be appropriate for applications of the Rényi car-parking model in which there is a reduced probability of cars parking bumper to bumper.