Composite

The growing concerns about the environment and energy have driven the widespread adoption of new lightweight materials such as polymer composites in many industrial sectors, crucial issues being performance, cost efficiency, and multifunctionality (Krawczak, 2019). Among them, thermosetting matrix composites offer not only many advantages such as high specific stiffness and strength and their consolidated use in primary aircraft structures but also technical issues such as long processing times, limited fracture toughness, reduction of mechanical properties in the presence of water and solvents, and difficulty of end-of-life treatment (Krawczak, 2011). A key cultural problem is associated with the need of a chemical reaction during part fabrication performed in mechanical/aerospace/naval industries.

Although the use of thermoplastic matrix composites in aeronautic structures has been proposed since the second half of the 80s (Nguyen and Ishida, 1987; Maffezzoli et al., 1989), their first application was at the beginning of the third millennium with the wing leading edge of Airbus A380 (Offringa, 2005). Their demand is continuously increasing (JEC Observer, 2020) since they offer many advantages such as high toughness, long storage time, easy repairing and recycling, higher performances in hot-wet conditions, and ability to be thermoformed and heat-welded. However, manufacturing issues such as high processing temperature, fiber impregnation, and warpage still need a deeper knowledge (Advani and Hsiao, 2012). Thermoplastic composites can play a key role in the 21st century industry as new materials are emerging day by day, as manufacturing processes are evolving to meet the severe industrial requirements of performance, production, and multifunctionality (Advani and Hsiao, 2012; Boisse, 2015), and as sophisticated numerical simulation tools are making virtual prototyping and engineering more reliable than ever (Binétruy et al., 2015; Boisse, 2015). In that field, innovation is multifaceted and may come either from the constitutive materials (high-performance engineering thermoplastic matrices, commingled semipreg of fibers/thermoplastics, self-healing, bio-based or biodegradable matrices, natural or thermoplastic fibers, 3D textile reinforcement…) or from the manufacturing processes (automated out-of-autoclave processes, hybridization/coupling of technologies, additive manufacturing, hybrid welding…). Moreover, thermoplastic composites allow for automated, high-speed mass production with reduced need for secondary operations (Mafeld, 2014), creating increased interest in the industry for various applications: aerospace and defense, automotive and rail transportation, construction and building, energy, oil and gas, sporting goods, drones, etc. Also, thermoplastic composites offer an interesting recycling potential using mechanical, thermal, or chemical processes (Oliveux et al., 2015). As thermoplastics, it is quite easy to recycle them by regrinding, compounding/blending, and reprocessing; additionally, they are at the forefront of current industrial scale-up attempts of chemical recycling, making it possible to recover not only fibers but also feedstock or original monomers which can eventually be re-polymerized to produce new polymers.
This Research Topic focuses on the latest advances and developments of fiber-reinforced thermoplastics, mainly referring to continuous fiber-reinforced composites and of related processing technologies. A collection of seven articles addresses some challenging issues related to advanced manufacturing processes, such as consolidation by compression molding (Ayadi et al.), injection-overmolding (Akkerman et al.), reactive pultrusion (Zoller et al.), joining by ultrasonic (Villegas) or induction (Scarselli et al.) welding, as well as solid-state drawing (Walker et al.) or electrospinning (Sessini et al.) of fibers. Numerical modeling and simulation, and performance assessment through advanced characterization techniques, correlating microstructure and properties, are also addressed. These papers highlight how thermoplastic matrix composites can be processed, adopting a completely different paradigm in comparison to thermosetting matrix ones, the former not requiring a reaction to set the properties but complex thermal cycles, often performed in a short time span.
The Guest Editorial team is confident that this collection of papers will benefit a large community in research and application of advanced thermoplastic composite materials so as to further advance along the pathway toward sustainability, performance, and competitiveness.

Thermally-driven decomposition of various organosilicon derivatives under a neutral gas atmosphere constitutes a reliable way for the preparation of carbon/silicon carbide C/SiC composites (modified car-bon materials) in the nanosized range. The two-stage aerosol-assisted synthesis method appears to be especially well suited to fabricate such materials while offering spherical particle morphology with tai-lored particle size capability. In this method, in the first stage an aerosol mist is generated from a liquid precursor system and transported in a neutral gas stream to a pre-heated ceramic tube reactor where com-plex physical and chemical changes take place resulting in the formation of solid particles collected on an exit filter. The raw product is usually pyrolyzed in the second stage at appropriately high temperatures to complete the anticipated removal of residual oxygen if excess C is present via carbothermal reduction. In this study, preliminary results on the target C/SiC ...

Over a decade ago, Dresselhaus predicted that low-dimensional systems would one day serve as a route to enhanced thermoelectric performance.In this article, recent results in the thermoelectric properties of nanowires and nanotubes are discussed. Various synthesis techniques will be presented, including chemical vapor deposition for the growth of thermoelectric nanostructures in templated alumina.Electrical transport measurements of carbon nanostructures, such as resistivity and thermopower, have revealed some very interesting thermoelectric properties.Challenges still remain concerning the measurement of individual nanostructures such as nanowires.Much work has been performed on the thermoelectric properties of carbon nanotubes, and these results will be highlighted.In addition, routes for enhanced thermoelectric materials have focused on incorporating nanostructures within the bulk materials.The role of these “hybrid composite structures” based on nanomaterials incorporated into t...

Purpose: The aim of this study was to determine effect of compressive cyclic loading on fatigue resistance and microleakage of monolithic CAD/CAM molar ceramic and composite crowns. Materials and Methods: Thirty-two extracted molars were prepared to receive ...

Mg–6Zn–5Al–4RE (RE= Mischmetal, mass%) alloy was prepared by metal mould casting method. The microstructure and mechanical properties of the as-cast and heat-treated alloys were investigated. The results show that the phase compositions of the as-cast state alloy are supersaturated solid solution α-Mg, lamellar β-Al12Mg17, polygonal Al3RE and cluster Al2REZn2 phases. The mechanical properties, especially the ultimate tensile strength and elongation of the alloy were significantly improved by the heat treatment. Fracture surface ...

—knitted fabrics find numerous applications in sportswear fabric industry, during their use it can be subjected to loading-unloading due to the body movements which can be indirectly affected by the dynamic elastic recovery value of the fabrics. The cyclic loads lead to the redistribution of fibers in the yarn structure, because they tend to get the minimum level of energy. Dimensional properties of knitted fabric are widely affected by the externally applied forces that could involve permanent deformation. Cotton/Spandex knitted fabrics are widely used for several applications. In this work, an attempt was done to analyze the effect of cyclic loading on cotton/spandex knitted fabric subjected to the different levels of cyclic loading under different values of initial extensions. Knitted fabric mechanical properties with different percentages of spandex were tested. The fabric properties and the number of cycles indicate the change of the residual extension and the drop in the fabric strength and stiffness.

The paper provides an overview of tribological properties of nanocomposites with aluminium matrix. Nanocomposites represent a new generation of composite materials with better properties than conventional composite materials. The paper presents and explains the most common methods of nanocomposites production. In addition, the overview of tribological properties is presented through the equipment used for testing; amount, size and type of reinforcement; matrix material and manufacturing process; and test conditions. ARTICLE HISTORY Received 15 August 2016 Accepted 3 September 2016 Available online 30 September 2016

Composite materials have gained traction in the world today and are becoming of
common use in industrial and specialized applications in general due to their flexible
nature that involves mixing through layers or matrixes the components of various
substances and therefore, a percentage of each substance’s physical properties. In
recent years there has been an increasing concern for industries to use cost effective
reinforcement for metal materials like aluminum which is abundant cheap, with
various desirable properties like its lightness, but lacks the strength for various
applications – ceramic materials such as SiC and aluminum oxide are used generally
for reinforcing the aluminum MMC. There is a good probability, backed up by tests
for certain materials, that reinforcing metals with composites can increase failure
displacement, fatigue life, ultimate failure load and energy absorption capacity,
amongst many others by substantial amounts.

An overview of the micromechanical theoretical and numerical models of wood is presented. Different methods of analysis of the effects of wood microstructures at different scale levels on the mechanical behaviour, deformation and strength of wood are discussed and compared. Micromechanical models of deformation and strength of wood are divided into three groups: cellular models (applied most often to the mesoscale or cell scale analysis of the wood deformation), continuum micromechanics and homogenization based methods, models which consider wood as a composite and are applied mainly to the analysis of wood at the microscale (cell wall scale) level and multiscale models. Lattice and composite models, which are used to analyze the damage and fracture of wood, are considered in a separate section. The areas of applicability and strong sides of each approach are discussed.

Natural fiber–biopolymer composites have been prepared using flax and poly(3-hydroxylbutyrate) bipolyesters (PHB). The biopolyesters consist of the homopolyester PHB and its copolymers with 5 and 12% 3-hydroxyvalerate (PHV). These biopolymer–natural fiber composites provide structures totally composed of biodegradable and renewable resources. The adhesion between the fibers and the polyesters was better than for analogous polypropylene composites. Wetting of the fibers by the polyesters was observed using scanning electron microscopy. The composites were limited by the properties of the polyesters. PHB is a brittle polymer though flexibility is improved in its copolymers with PHV, but at the expense of crystallization rate. Nucleation was increased by the fibers and silane coupling agent used as adhesion promoter. The melting temperature was influenced by the promoted adhesion and copolymerization. The bending modulus was increased in the composites and dynamic mechanical analysis provided storage modulus of as much as 4 GPa at 25°C with a smaller component as the loss modulus. The maximum in the loss modulus curve was taken as the glass transition temperature, and this increased in the composites. The influence of silane coupling agent was found beneficial for the material properties of the biopolyester–flax composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2114–2121, 2004

Composites are made by combining of two or more different materials, which are having different characteristics. Composites materials are widely used today in various applications. Pultrusion process is used to manufacture composite material, in these process different types of roving of glass, carbon, aramid fibres are used to make different pultruded material as per their application. Pultruded product which are various types of shape like C-channel, I-beam, square pipe, circular pipe etc…, Today pultruded products are used in various applications like bridges, FRP ladders, communication tower, cooling tower, etc…There are several products of pultrusion products used in different application, but we have to analyze different products uses for a special application in terms of strength.

In the global golf ball market, in order for relatively small golf equipment companies to increase their influence, target marketing through market segmentation and development of golf ball products are necessary. In addition, in order to improve competitiveness, it is necessary to find core technological competencies of companies, intensively foster them, and apply them to products. Therefore, in this study, first, the golf ball market is segmented according to golf players. In addition, it proposes targeted marketing and advanced materials application plans based on segmentation data. Through this, it is suggested that relatively small golf equipment manufacturers can effectively enter the golf equipment market. Moreover, by proposing a golf ball using a new material, carbon nanotube, it is intended to present a method of convergence development.

The increase in consumption of coconut usage every year leads to the production of the fiber of it, presently a very less quantity of coconut husk is used in domestic application mainly as a fuel and remaining as waste which is directly proportional to the quantity of coconut cultivated. The main thrust of present research work is to explore the possibility of utilizing coconut husk fibers as reinforcement for composites with the appropriate matrix material. The fiber reinforced plastic composites made of areca fibers extracted from areca were prepared with used plastics. The composite material prepared with different proportion of reinforcement and matrix material. The required dimensions of the die were prepared using mild steel. The matrix material is placed layer by layer with reinforcement in the die. The die is designed to heat the material to its semi-liquid state with the help of heater at the bottom of the die. The material is compacted by an applying a force 500 kgf and soaked in a die for 2 hours at 115C. Then the composite is allowed to cool to room temperature. The resulted composite is cut into required dimensions to carry out mechanical properties of it; they are Tensile strength, bending strength, and compression strength and impact tests. The results of the mechanical properties of composites are quite competitive with existing plywood planks. The composite is also tested for threading operation by tapping and it shows tapping is obtained successfully in the composites.

This paper presents a study of an ongoing research project on the use of new composites for enhancement
of the performance of concrete beams. A plain concrete beam was externally bonded with wire mesh–
epoxy composite using one to five wire mesh layers. The flexural performance of the beam specimens
bonded with wire mesh layers was compared with the beam specimens bonded with carbon fibre as well
as a hybrid of wire mesh–epoxy–carbon fibre composite. The test results show that the use of wire mesh
with epoxy is an efficient way to improve the flexural performance of concrete beam specimens. The
increase in wire mesh layers significantly enhances the flexural strength, cracking behaviour and energy
absorption capability. In comparison with carbon fibre, wire mesh–epoxy composite is more efficient in
flexural strength and ductility. In addition, it was found that a concrete beam bonded with a hybrid wire
mesh–epoxy–carbon fibre composite has significantly more energy absorption capability compared to
specimens bonded with only carbon fibre.

Carbon fiber reinforced polymers (CFRPs) are one the stiffest and lightest composite materials, they are much convincing than other conventional materials in many fields and applications. Use of composites is limited due to their higher rice and lower formability. Use of nanoparticles increases mechanical properties of these composites. As these composites are costly materials, Non Non-destructive testing (NDT) such as Eddy current pulsed thermography (ECPT) is used for studying properties against impact loading. Modifying composite papers with Hot Melting Fibers (HMF) shows increase in mechanical properties without considerable reduction in electrical properties.

Composite propellant mainly contains hydroxyl-terminated poly (butadiene) (HTPB) based binder and oxidizer like ammonium perchlorate (AP). The mechanical properties requirement of composite propellant is very stringent. The mechanical properties of the final product is mainly depends on the microstructure of HTPB prepolymer binder. In HTPB, three different types of microstructures are possible like cis, trans and vinyl. In this article, three different grades of HTPB are subjected for experimentation. Quantification of cis, tans and vinyl microstructure were carried out by peak area calculation in characteristic Nuclear Magnetic Resonance (NMR) peak. Gel permeation chromatography (GPC), rheology and simultaneous thermal analysis (STA) were also carried out with different grades of prepolymer. The correlation of microstructures concentration with various properties like molecular weight, polydispersity, rhelogy and thermal properties were also established. The composite propellants processed from these various HTPB prepolymers, were also evaluated by means of physicochemical and internal ballistic properties. Composite propellant produced from prepolymer containing higher cis and trans concentration i.e. HTPB Grade II showed better tensile mechanical properties. Marginal variations were observed in internal ballistic properties.

Effect of long-term orthodontic treatment on salivary nickel and chromium has not been quite assessed except in few retrospective studies with controversial results. The aim of this prospective study was to measure salivary levels of these ions during 1 year of orthodontic treatment. Saliva samples were collected from 20 orthodontic patients, before treatment (control) and 6 and 12 months later. Nickel and chromium concentrations were determined using atomic absorption spectrophotometry. Data were analyzed using one- and two-way repeated-measures ANOVA, Bonferroni, Friedman (α = 0.05), and Wilcoxon signed-ranks tests (α = 0.016). Average nickel level changed from 9.75 ± 5.02 to 10.37 ± 6.94 and then to 8.32 ± 4.36 μg/L in 1 year. Average chromium concentration changed from 3.86 ± 1.34 to 4.6 ± 6.11 and then to 2.04 ± 1.66 μg/L. Alterations in nickel values were not statistically significant [P = 0.468 (ANOVA)], but fluctuations in chromium levels were [P = 0.021 (Friedman)]. The dec...

Composite materials have gained traction in the world today and are becoming of common use in industrial and specialized applications in general due to their flexible nature that involves mixing through layers or matrixes the components of various substances and therefore, a percentage of each substance's physical properties. In recent years there has been an increasing concern for industries to use cost effective reinforcement for metal materials like aluminum which is abundant cheap, with various desirable properties like its lightness, but lacks the strength for various applications-ceramic materials such as SiC and aluminum oxide are used generally for reinforcing the aluminum MMC. There is a good probability, backed up by tests for certain materials, that reinforcing metals with composites can increase failure displacement, fatigue life, ultimate failure load and energy absorption capacity, amongst many others by substantial amounts.

Bu çalışmada, 18 saat öğütülmüş Magnezyum (Mg) tozlarının, toz metalürjisi yöntemi ile belirli sıcaklık ve zaman parametrelerinde üretilen numunelerin özelikleri kategorize edilerek magnezyum matrisli kompozit malzeme üretimi için bir ön hazırlık yapılması hedeflenmektedir. Sinter Sıcak Press HP15-3000 makinesi ile basılan %90’ın üzerinde bir yoğunluğa sahip 18 saat Öğütülmüş magnezyum tozundan üretilen numunelerin optik mikroskopla yüzey görüntülerini alınıp, sertlik ve basma testleri yapılarak numuneler belirlenen parametrelerde karşılaştırmalı olarak incelenmiştir.
Üretilen numunelerin çapı 10,25 mm, boyu 10 mm olacak şekilde hedeflenmiş numune üretimi gerçekleştirilmiştir. Yapılan çalışmalarda mekanik özelliklerini analiz etme ve deney tasarımlarını dahi iyi gerçekleştirebilmek için Design–Expert kullanılarak istatistiksel veriler toplanmıştır.

Anahtar Kelimeler: Toz Metalürji, Magnezyum (Mg), Kompozit, Sinterleme, Alaşımlama