Search

Abstract: Ultimate tensile strength of three continuous fiber-reinforced ceramic matrix composites, including SiCf/CAS-II (1D), SiCf/MAS-5 (2D) and SiCf/SiC (2D), was determined as a function of load (test) rate in air at 1100–1200°C. All three composites exhibited a significant dependency of ultimate tensile strength on test rate. The application of the preload technique as well as the prediction of life from one loading configuration (constant stress-rate) to another (constant stress) suggested that the overall phenomenological macroscopic failure mechanism of the composites would be a power-law type of slow crack growth or damage evolution/accumulation. It was further found that constant stress-rate testing could be used as an alternative to life prediction test methodology for ceramic matrix composites, at least for a short range of lifetimes and when ultimate tensile strength is used as a failure criterion. [Copyright &y& Elsevier]

When the cocoa pod husk (CPH) is used and processed, two types of flour were obtained and can be differentiated by particle size, fine flour (FFCH), and coarse flour (CFCH) and can be used as a possible reinforcement for the development of bio-based composite materials. Each flour was obtained from chopping, drying by forced convection, milling by blades, and sieving using the 100 mesh/bottom according to the Tyler series. Their physicochemical, thermal, and structural characterization made it possible to identify the lower presence of lignin and higher proportions of cellulose and pectin in FFCH. Based on the properties identified in FFCH, it was included in the processing of thermoplastic starch (TPS) from the plantain pulp (Musa paradisiaca) and its respective bio-based composite material using plantain peel short fiber (PPSF) as a reinforcing agent using the following sequence of processing techniques: extrusion, internal mixing, and compression molding. The influence of FFCH contributed to the increase in ultimate tensile strength (7.59 MPa) and higher matrix–reinforcement interaction when obtaining the freshly processed composite material (day 0) when compared to the bio-based composite material with higher FCP content (30%) in the absence of FFCH. As for the disadvantages of FFCH, reduced thermal stability (323.57 to 300.47 °C) and losses in ultimate tensile strength (0.73 MPa) and modulus of elasticity (142.53 to 26.17 MPa) during storage progress were identified. In the case of TPS, the strengthening action of FFCH was not evident. Finally, the use of CFCH was not considered for the elaboration of the bio-based composite material because it reached a higher lignin content than FFCH, which was expected to decrease its affinity with the TPS matrix, resulting in lower mechanical properties in the material. [ABSTRACT FROM AUTHOR]

This study focuses on the synthesis of a Zn-Al alloy nanocomposite, incorporating varying weight percentages (2, 4, 6, and 8 wt.%) of SiC nanoparticles with an average size of 30 nm. The preparation was carried out using the stir casting technique. Experimental tests, including hardness, compression, and tensile tests, were conducted on both the Zn-Al alloy and its composite. Furthermore, the surface morphology of the materials was examined using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The mechanical properties and microstructure of the composite samples were assessed. The results indicate that an increase in the weight percentage of SiC nanoparticles led to corresponding increases in hardness, compression strength, and ultimate tensile strength of the composite materials. When compared to an unreinforced alloy, nanocomposites reinforced with 2, 4, 6, and 8 wt.% SiC nanoparticles exhibited hardness improvements of 9.1%, 15%, 20.8%, and 30% respectively, as well as increases in ultimate tensile strength of 2.56%, 4.46%, 7.74%, and 12.21%, and compression strength enhancements of 17.5%, 20%, 22.4%, and 31.5% respectively. Notably, the composite sample containing 8% weight of reinforcement consistently demonstrated the highest ratings in terms of hardness, tensile strength, and compression strength. Based on the scanning electron microscopy (SEM) results, the nanocomposite alloy exhibits a dendritic morphology, with evenly distributed silicon carbide (SiC) particles embedded within the metal matrix. Furthermore, the interface between the SiC particles and the metal matrix demonstrates a strong bond. As a consequence, the mechanical properties of the fabricated composites were significantly improved. [ABSTRACT FROM AUTHOR]

This study synthesized and characterized the Ti-4822 matrix composites via Ti/Al transition layer introducing TiB and Ti 2 AlC, which was produced by spark plasma sintering. The grain size of composites decreased significantly from 221.5±5 μm to 61.2±5 μm with the increase of B 4 C content, mainly due to the pinning effect of in-situ generated primary TiB and Ti 2 AlC ceramic phases at grain boundaries, which limited the rapid grain growth of the matrix. The ultimate tensile strength and total fracture elongation of the alloy were 433.5 MPa and 13.3% at 800 °C, correspondingly. With 0.3 wt% addition of B 4 C, the composite exhibited superior strength (494.5 MPa) and ductility (22.5%) at the same tensile temperature. The reinforced strength of the composite was mainly attributed to the grain refinement and precipitation strengthing. In addition, the primary TiB and Ti 2 AlC were stapled at the grain boundary as the primary protective net, and the secondary TiB and Ti 2 AlC were stapled between the interlamellar as the secondary protective net, which significantly improved the microstructure stability of the composites at high temperature. [ABSTRACT FROM AUTHOR]

This paper focuses on the preparation and characterization of the reinforcement of an epoxy with metakaolin clay of grain size (45 ≤ d ≤60) µm as an eco-friendly inorganic material to improve its mechanical and physical properties with low-cost filler. Various proportions of (0, 15, 30, 45, and 60) wt.% of metakaolin were intrinsically mixed with epoxy to investigate their physical properties represented by moisture absorption. Tensile test was employed to determine their mechanical properties such as ultimate tensile strength, yield strength, modulus of elasticity, as well as compressive strength, flexural strength and Vickers hardness test which was used to specify hardness number. The obtained experimental results showed improvement in the modulus of elasticity, compressive strength, and hardness with the addition of metakaolin. In contrast, the yield and tensile strength of the composite specimens which decrease with the increase in metakaolin content. Also, absorption of moisture test at different immersion times was carried out with different filler loadings of the prepared composite. The results of the test showed that a decreasing in water uptake for specimens with higher metakaolin content. From optical surface investigation using an optical microscope, it was found a reduction in porosity with an increase in the concentration of metakaolin and the specimen with weight percent of 60% is the highest homogeneity and less porosity and voids as compared to the other specimens. The prepared composite may find potential practical applications such as anti-corrosion coating, automotive components and medical devices. [ABSTRACT FROM AUTHOR]

Textile-reinforced highly ductile concrete (TRHDC) was a promising composite material, which exhibited multiple crack characteristics, high cracking and ultimate tensile strength under uniaxial tension. In this study, six precast hollow-core slabs including one reference slab and five TRHDC-strengthened slabs were manufactured and tested as simply supported under four-point bending. The parameters under investigation included: (i) the TRHDC matrix added with or without polyvinyl alcohol (PVA) fibers, and (ii) the number of textile layers. The test results indicated that adding PVA fibers in the TRHDC matrix could effectively limit the crack width of TRHDC composites, and multi-crack behavior was observed in the strengthening overlay. Besides, TRHDC composites were efficient in enhancing the flexural capacity of strengthened slabs, which were 70–113% in cracking load, and 74–132% in peak load compared with the reference slab. Finally, based on the plane section assumption, an analytical model was given to predict the flexural capacity of TRHDC-strengthened slabs. [ABSTRACT FROM AUTHOR]

Friction stir welding is a technique of combining harmless for the environment because it doesn’t use flux or any other shield gas and doesn’t produce hazardous gas. To study the FSW process on composite material this work offers an experimental enquiry and optimisation technique. In this investigated how input process operating factors like tool rotational speed, feed rate and depth of cut affect an output parameter like hardness of welded connections and Ultimate Tensile Strength (UTS), Microstructure and metallurgical on the metal. To achieve this L27 Taguchi approach orthogonal array used to optimise design tests on friction stir welding parameters and also HCHCr tool used to improve the good weld ability and to increase the heat input. The experimental setup is run with several combinations of process parameters such as 900, 1000, and 1200 rpm of Tool rotational speed 20 mm, 25 and 30 mm as feed rate by adjusting the depth of cut values of 5.4 mm, 5.6 mm and 5.8 mm respectively. Additionally, utilising the regression analysis equations (ANOVA) used to identify the significant input parameters how it effects for the output metal structure. Finally, by achieved effective evaluation of the metallurgical and microstructure on the nylon 6A metal by various analysis and Testing. [ABSTRACT FROM AUTHOR]

Purpose: This research outlines the development and characterization of advanced composite materials and their potential applications in the aerospace industry for interior applications. Advanced composites, such as carbon-fiber-reinforced polymers and ceramic matrix composites, offer significant advantages over traditional metallic materials in terms of weight reduction, stiffness and strength. These materials have been used in various aerospace applications, including aircraft, engines and thermal protection systems. Design/methodology/approach: The development of design of experiment–based hybrid aluminum composites using the stir-casting technique has further enhanced the performance and cost-effectiveness of these materials. The design of the experiment was followed to fabricate hybrid composites with nano cerium oxide (nCeO2) and graphene nanoplatelets (GNPs) as reinforcements in the Al-6061 matrix. Findings: The Al6061 + 3% nCeO2 + 3% GNPs exhibited a high hardness of 119.6 VHN. The ultimate tensile strength and yield strength are 113.666 MPa and 73.08 MPa, respectively. A uniform distribution of reinforcement particulates was achieved with 3 Wt.% of each reinforcement in the matrix material, which is analyzed using scanning electron microscopy. Fractography revealed that brittle and ductile fractures caused the failure of the fractured specimens in the tensile test. Practical implications: The manufactured aluminum composite can be applied in a range of exterior and interior structural parts like wings, wing boxes, motors, gears, engines, antennas, floor beams, etc. The fan case material of the GEnx engine (currently using carbon-fiber reinforcement plastic) for the Boeing 7E7 can be another replacement with manufactured hybrid aluminum composite, which predicts weight savings per engine of close to 120 kg. Originality/value: The development of hybrid reinforcements, where two or more types of reinforcements are used in combination, is also a novel approach to improving the properties of these composites. Advanced composite materials are known for their high strength-to-weight ratio. If the newly developed composite material demonstrates superior properties, it can potentially be used to replace traditional materials in aircraft manufacturing. By reducing the weight of aircraft structures, fuel efficiency can be improved, leading to reduced operating costs and environmental impact. This allows for a more customized solution for specific application requirements and can lead to further advancements in materials science and technology. [ABSTRACT FROM AUTHOR]

Epoxy resins have great potential for industrial applications because of their excellent properties such as good adhesion, durability, higher strength, and so forth. But, their high‐viscosity limits industrial usage. Reducing the viscosity with suitable diluents provides an advantage on industrial scale processing, but this also causes a decrease in their chemical and mechanical properties. The production of epoxy‐based composite materials provides good mechanical, heat, and solvent resistance properties. Therefore, determination of additives amount and dilution ratio for specific working area are important for these materials. In this context, this study first includes synthesis of bisphenol A‐based epoxy resin and characterization with fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Second, chemical, mechanical, thermal, and surface properties of the resin were investigated by varying the reactive/nonreactive diluents and additives. Multiwall carbon nanotube (MWCNT‐modified with triton X‐405 nonionic surfactant) and fumed silica as additives were used in this study. Mechanical and chemical tests were applied to 49 types of materials. In order to see the significance levels and synergistic effects of diluents on tensile strength, 3D graphs were obtained with the experimental and modeled data. ANOVA was also performed for significance levels of the diluents. After that, the effects of silica and carbon nanotube additive on tensile strength were investigated. As a result of the tensile test and TGA analysis of the pure epoxy, the ultimate tensile strength was measured as 59.07 MPa, Tg (°C), and Tm (°C) values were found as 175.5 and 304.0°C. These results increased for the nanocomposite material prepared with 2% fumed silica and 0.1% MWCNT (modified YAM) as 81.64 MPa, 192.2 and 333.3°C. It was also shown that the ultimate tensile strength, which decreased with dilution of pure epoxy, could be increased significantly with the additives. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the variables of the fused deposition modelling (FDM) process and improve their effect on the mechanical properties of acrylonitrile butadiene styrene (ABS) components reinforced with copper microparticles. Design/methodology/approach: In the experimental approach, after drying the ABS granule, it was mixed with copper microparticles (at concentrations of 5%, 8% and 10%) in a single screw extruder to fabricate pure ABS and composite filaments. Then, by making the components by the FDM process, the tensile strength of the parts was determined through tensile strength tests. Taguchi DOE method was used to design the experiments in which nozzle temperature, filling pattern and layer thickness were the design variables. The analysis of variance (ANOVA) and signal-to-noise analysis were conducted to determine the effectiveness of each FDM process parameter on the ultimate tensile strength of printed samples. Following that, the main effect analysis was used to optimize each process parameter for pure ABS and its composite at different copper contents. Findings: The study allows the layer thickness and filling pattern had the highest effects on the ultimate tensile strength of the printed materials (pure and composite) in the FDM process. Moreover, the results show that the ultimate tensile strength of the ABS composite containing 5% copper was nearly 12.3% higher than the pure ABS part. According to validation tests, the maximum error of experiments was about 0.96%. Originality/value: In this paper, the effect of copper microparticles (as filling agent) was investigated on the ultimate tensile strength of printed ABS material during the FDM process. [ABSTRACT FROM AUTHOR]

• An (AlN + AlB 2) /Al composite reinforced with both ex–situ and in–situ AlN was prepared. • The ex–situ AlN particles were coated by in–situ AlN nanolayers. • The ultimate tensile strength of the composite can be 416 MPa at 25 °C and 242 MPa at 350 °C. In this paper, an (AlN + AlB 2)/Al composite was produced via liquid–solid reaction. Except for in–situ formed AlN and AlB 2 phases, a nanolayer with the thickness of roughly 10 nm was found coating the ex–situ AlN. The nanolayer has the same crystal structure with ex–situ AlN, which is supposed beneficial for the combination between ex–situ AlN and Al matrix. The composite exhibits attractive ultimate tensile strength at 25 °C and 350 °C, which is 416 MPa and 242 MPa, respectively. [ABSTRACT FROM AUTHOR]

Tribo-mechanical experiments were performed on Glass Fiber Reinforced Polymer (GRFP) composites against different engineering materials, and the tribological behavior of these materials under dry conditions was investigated. The novelty of this study consists of the investigation of the tribomechanical properties of a customized GFRP/epoxy composite, different from those identified in the literature. The investigated material in the work is composed of 270 g/m2 fiberglass twill fabric/epoxy matrix. It was manufactured by the vacuum bag method and autoclave curing procedure. The goal was to define the tribo-mechanical characteristics of a 68.5% weight fraction ratio (wf) of GFRP composites in relation to the different categories of plastic materials, alloyed steel, and technical ceramics. The properties of the material, including ultimate tensile strength, Young's modulus of elasticity, elastic strain, and impact strength of the GFPR, were determined through standard tests. The friction coefficients were obtained using a modified pin-on-disc tribometer using sliding speeds ranging from 0.1 to 0.36 m s−1, load 20 N, and different counter face balls from Polytetrafluoroethylene (PTFE), Polyamide (Torlon), 52,100 Chrome Alloy Steel, 440 Stainless Steel, and Ceramic Al2O3, with 12.7 mm in diameter, in dry conditions. These are commonly used as ball and roller bearings in industry and for a variety of automotive applications. To evaluate the wear mechanisms, the worm surfaces were examined and investigated by a Nano Focus—Optical 3D Microscopy, which uses cutting-edge μsurf technology to provide highly accurate 3D measurements of surfaces. The obtained results constitute an important database for the tribo-mechanical behavior of this engineering GFRP composite material. [ABSTRACT FROM AUTHOR]

Abstract: The influence of ZrC content on the tensile deformation behavior and fracture strength of ZrCp/W composites in a temperature range of 800–1400°C was investigated. Both of the non-linear feature of the stress–strain curve and the rupture strain of the composites decreased with increasing ZrC content from 20 to 50vol% in all the tested temperatures. The maximum ultimate tensile strength of each ZrCp/W composite was found in the temperature range of 1000–1200°C. With increasing ZrC content from 20 to 50vol%, the maximum ultimate tensile strength of the ZrCp/W composite was decreased due to the porosity increase and the plasticity decrease of the composite although ZrC enhanced the tungsten matrix via load transferring and blocking dislocation movement in tungsten matrix. [Copyright &y& Elsevier]

• The self-recovery performance of SMAF-ECC under cyclic tensile loading were studied, which can provide important basis for establishing a tensile theoretical model. • SMA fibers increase the ultimate strain and ultimate tensile strength of the specimens, and significantly reduce the residual crack width and residual deformation. • The influence of SMA fiber diameter and fiber content to the self-recovery performance of the specimens was studied and analyzed. • The stress state of SMA fibers during the loading process was investigated, providing a basis for evaluating the performance of SMA superelasticity. The incorporation of superelastic shape memory alloy (SMA) fibers into engineered cementitious composites (ECC) has led to a novel composite material, SMAF-ECC, which possesses excellent deformation, energy dissipation, and self-recovery capabilities. To understand the self-recovery performance of this new composite material under tensile loading, this study conducted uniaxial cyclic tension tests on SMAF-ECC specimens to investigate stress, strain, crack width, strain recovery rate, and crack recovery rate, while also considering the primary influencing factors such as SMA fiber diameter and content. The results indicate that the addition of SMA fibers improves the ultimate strain and ultimate tensile strength of ECC; increasing fiber content effectively enhances the strain and crack recovery rates of SMAF-ECC specimens, with the maximum strain recovery rate and crack recovery rate of the tested specimens reaching 69% and 77%, respectively. Both too large and too small SMA fiber diameters lead to reduced recovery rates. In this experiment, when the fiber diameter was 0.5 mm, the strain and crack recovery rates of the specimens were the highest, with a crack recovery rate of 53%, approximately 1.7 times that of specimens with 1 mm and 0.2 mm diameter SMA fibers. These findings provide a reliable basis for establishing a theoretical model of the tensile mechanical properties of SMAF-ECC composite materials. [ABSTRACT FROM AUTHOR]

Recent developments in mechanical applications have led to the development of metal matrix composites, which represent the future of composite structures. Al7010 aluminium alloy matrix with nano-ZrO2 and graphene particle reinforced composite is created in this experiment. By adopting the stir casting procedure in two different casting, 2 percent reinforcement of zirconium dioxide and 1 percent of graphene is included in the composite materials. The composite's metallurgical and mechanical characteristics are studied. The SEM image demonstrates uniform dispersion of the particles in the alloy matrix. The manufactured material's ability to gather particulate matter is clearly found in SEM and EDS. The addition of zirconia particles works together to prevent the alloy matrix from dislocating, which increases the base material's hardness as well as its tensile resistance. Similar results are also found in graphene-casting material. Results from tensile tests reveal that adding nano-zirconium dioxide particle (ZrO2) and graphene boosts the material's tensile and hardness strength. In terms of the ultimate tensile strength (UTS), the Al7010/2% ZrO2 composite had a 6% increase and Al7010/1% graphene had a 5.5% increase above the Al7010 alloy. Compared to Al7010 alloy, the microhardness of Al7010/ZrO2 is 17.64% greater and Al7010/1% graphene is 14% greater. [ABSTRACT FROM AUTHOR]

Innovative, nanotechnologies-featuring dental materials for CAD/CAM applications are becoming available. However, the interaction with the oral environment poses critical challenges to their longevity. The present study evaluated specific physical-chemical properties and antimicrobial potential of a CAD/CAM graphene-doped resin before and after accelerated aging protocols. Graphene nanofibers (GNF)-doped (<50 ppm) PMMA (GPMMA) and control PMMA CAD/CAM discs were used. Specimens underwent aging procedures of their bulk (thermo- and load-cycling) and surface (24 h-immersion in absolute ethanol), then they were tested for flexural strength, ultimate tensile strength, sorption/solubility, and methyl-methacrylate elution. Surface characterization included x-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, surface roughness, microhardness, and scanning electron microscopy (SEM). Adherence of Streptococcus mutans and Candida albicans , and biofilm formation (continuous-flow bioreactor) by the same strains and an artificial oral microcosm were investigated. GNF-doping improved the physical-chemical bulk properties of the PMMA resin. Surface aging reduced microhardness and increased the roughness of both test and control materials. Surfaces displayed signs of swelling and degradation at SEM. Microbiological data of non-aged surfaces showed that GNF-doping significantly reduced biofilm formation by all tested strains despite having no impact on microbial adherence. After aging, microbial adherence was higher on GPMMA surfaces, while biofilm formation was not promoted. GNF-doping improved the material's performance and influenced its antimicrobial potential. This strategy seems a valuable option to overcome the effects of surface degradation induced by aging on the antimicrobial potential of PMMA resin. • Graphene nanofibers doping of PMMA resin improved its physical-chemical bulk properties. • Graphene nanofibers doping of PMMA significantly reduced biofilm formation. • Surface aging drastically deteriorated both graphene-PMMA and PMMA surfaces. • After aging, biofilm formation on graphene PMMA was not promoted. • Graphene nanofibers improved PMMA physical-chemical properties, reducing biofilm formation. [ABSTRACT FROM AUTHOR]

The use of carbon nanotubes (CNTs) as reinforcing phase in copper-based composites has been extensively studied. However, controlling the synthesis interface structure and explaining the nanoscale interface bonding mechanism through experimental methods still poses challenges. In this study, a model of single-walled carbon nanotube nanocrystalline copper composite was established based on molecular dynamics (MD) simulations to investigate the effects of grain boundaries and dislocations on the composite material. It was found that the addition of nickel atoms improved the interface bonding between carbon nanotubes and the copper matrix, reducing vacancies at the interface. Ni@SWCNT/Cu exhibited better mechanical properties. Structural changes and defect evolution during deformation were studied. The ultimate tensile strength of SWCNT/Cu and Ni@SWCNT/Cu composites increased by 62.29 % and 68.78 % respectively compared to nanocrystalline copper, while the Young's modulus increased by 25.91 % and 32.48 % respectively; moreover, the Young's modulus of these two composites increased by 45.24 % and 49.42 % respectively. Ni@SWCNT/Cu had the lowest wear rate and friction coefficient, with a minimum wear rate of 0.0055 and a minimum friction coefficient of 0.67, demonstrating better wear resistance. The effects of different friction speeds and depths of indentation on the friction performance of the composite materials were also investigated. [ABSTRACT FROM AUTHOR]

• A variable blend of hybrid reinforcement particles was utilized for this study. • 100:0, 75:25, 50:50, 25:75, and 0:100 variable ratios of SiC:CeO 2 were used. • MP-FSP was successful in enhancing the distribution of the reinforcing particles. • 75:25 ratio emerged as the optimal configuration with superior properties. In the present work, hybrid surface composites (HSCs) were fabricated using aluminium 5052 alloy as base matrix and silicon carbide (SiC) and cerium oxide (CeO 2) as reinforcement particles via friction stir processing (FSP) technique. Varying reinforcement ratios of SiC and CeO 2 nano-powders, viz 100:0, 75:25, 50:50, 25:75, and 0:100 was used. Multi-pass FSP was employed to obtain improved dispersion of reinforcement particles. Results revealed the collaborative impact of SiC and CeO 2 particles on the mechanical properties of the SCs, shedding light on the optimal ratios for achieving superior mechanical performance. The hybrid ratio of (SiC: CeO 2) 75:25 was predominant in tensile strength enhancements with an ultimate tensile strength of 283 MPa compared to 269 MPa of BM while the percentage elongation increased to 21.6 as compared to 18.8 in BM. The average microhardness also improved to 92 HV compared to 85 HV. These results emphasised on the importance of HSC fabricated using 75:25 ratio of SiC:CeO 2 reinforcing particles. [ABSTRACT FROM AUTHOR]

This study investigates the effects of four variables during fused filament fabrication of organic biocompatible composite material, PLA with coconut flour, at the ultimate tensile strength (UTS), and elasticity module (E) of the printed parts. The parameter optimization uses Taguchi L18 design and regression models. The examined deposition variables are the layer thickness, the nozzle temperature, the raster deposition angle, and filament printing speed. The effects of the above variables on the strength of the parts are essential to enhance the mechanical response of the printed parts. The experimental outcomes are investigated using the ANOM and ANOVA and modeled utilizing linear regression models. In addition, an independent experiment was repeated three times at optimum parameters' levels to evaluate the methodology, giving predictions errors less than 3%. The observed results showed that the raster deposition angle dominates among the other variables in the studied experimental area. [ABSTRACT FROM AUTHOR]

The life-limiting behavior of an N720/alumina oxide/oxide ceramic matrix composite (CMC) was assessed in tension in air at 1200 °C for unimpacted and impacted specimens. CMC targets were subjected to ballistic impact at ambient temperature with an impact velocity of 250 m/s under a full support configuration. Subsequent postimpact ultimate tensile strength was determined as a function of test rate in order to determine the susceptibility to delayed failure or slow crack growth (SCG). Unimpacted and impacted specimens exhibited a significant dependency of ultimate tensile strength on test rate such that the ultimate tensile strength decreased with decreasing test rate. Damage was characterized using X-ray computed tomography (CT) and scanning electron microscopy (SEM). A phenomenological life prediction model was developed in order to predict life from one loading condition (constant stress-rate loading) to another (constant stress loading). The model was verified in part via a theoretical preloading analysis. [ABSTRACT FROM AUTHOR]

Abstract CNTs/Cu-Ti composites were fabricated successfully by spray pyrolysis, low energy ball milling and subsequent hot pressing (HP). Microstructure and mechanical properties of the composites were characterized by SEM, EDS, HRTEM, XRD, hardness and tensile tests. The results reveal that in situ generated nano-TiC particles, as a transition phase from CNTs to Cu-Ti matrix, which played a "rivet" role in enhancing the interfacial bonding between the CNTs and Cu-Ti matrix is formed in the composites. Consequently, mechanical properties of the CNTs/Cu-Ti composites are enhanced compared with alloy matrix, and an optimal balance between elevated ultimate tensile strength and impressively larger plastic deformation is achieved by adding 0.4 wt% CNTs in the composites. (ultimate tensile strength (UTS) 352 MPa, elongation 28.2%, the UTS is 39% higher than that of the Cu-Ti alloy, and the ductility increased significantly by 62%.) Finally, strengthening and toughening mechanisms are discussed. This study provides new insights into the interface structure and strength-ductility in metal-matrix composites. Highlights • CNTs reinforced Cu-Ti alloy composites were fabricated. • Spray pyrolysis method was used to achieve good dispersion of CNTs. • Dispersed CNTs facilitates the reaction with Ti atoms to form interfacial carbides. • CNTs was mixed in the form of coated nano-sized Cu 2 O particles. • Strength and toughness of the composites were improved simultaneously. [ABSTRACT FROM AUTHOR]

In this study, the potential of superelastic shape memory alloy (SMA) wire to enhance the tensile strength of a glass fibers reinforced epoxy composite was evaluated. Composite specimens with one embedded SMA wire fabricated with hand‐layup method. The specimens were placed under tensile loading (pre‐tension) and unloaded before ultimate tensile strength. The pre‐tension amounts were 65, 75, and 85% of ultimate tensile strength. After unloading, SMA wire wants to transform to the austenite phase and recover its primary shape and a large amount of compressive stress will be released over the composite specimens. Results show that the ultimate tensile strength for specimen with 75% pre‐tension was 32% higher than the composite without pre‐tension. This pre‐tension has the best effect on ultimate tensile strength and pretension of specimens before ultimate tensile strength leads to higher tensile strength due to the high superelasticity of the SMA wires. POLYM. COMPOS., 39:E2454–E2459, 2018. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Abstract In this paper, the study of the mechanical properties of composites consisting of electrodeposited Ni and co-electrodeposited SiC particles coated with a thin Cu layer was presented. It was demonstrated that the coating allowed to increase the concentration of ceramic particles in the composite. Although the plating parameters were the same for both types of composites, the concentration of SiC was 15% for the composite containing coated particles (Ni/SiC-Cu) and 10% for the composite containing uncoated particles (Ni/SiC). Furthermore, tensile tests showed that the Ni/SiC-Cu samples exhibited higher Young's modulus than the pure electrodeposited Ni samples or Ni/SiC samples. The measured Young's modulus of the Ni/SiC-Cu composite was 250 ± 10 GPa. However, the ultimate tensile strength of the Ni/SiC-Cu composite was lower than that of pure Ni. To explain the mechanical behaviour of the Ni/SiC-Cu composite, the microstructure of the interface of this composite and its bonding strength were studied. Microstructure studies conducted using a scanning electron microscope (SEM) revealed that the SiC/Cu interface was smooth and of good quality whereas the Cu/Ni interface was rough but also of good quality. The measured bonding, normal, and shear strength values demonstrated that the SiC/Cu interface was weak, and that was the main reason for the low ultimate tensile strength of the composite. The shear strength of the SiC/Cu interface was measured using a novel method: micropillars shearing including atomic force microscopy (AFM). Finally, a simple finite element model of the Ni/SiC-Cu composite, based on cohesive elements, was developed. [ABSTRACT FROM AUTHOR]

Abstract The mechanical behavior of Nextel 720 ceramic matrix composite fibers was modeled using a novel multiscale modeling technique called the Bridging Cell Method (BCM). The BCM divides the system into three domains: atomistic, bridging, and continuum; with seamless coupling between the atomistic and continuum domains. The BCM allows considering the effects of the nano- and micro-structural characteristics of the material when modeling a macro-scale bulk. It incorporates interatomic potentials and quasi-harmonic calculations to find the final state of the system. The mechanical properties of the as-received fibers were investigated in tension via microtesile testing. The experimental results – evaluated in terms of the ultimate tensile strength, failure strain, and elasticity of the fibers under uniaxial loads – stood within the range reported in the literature; these results were then used to validate the Nextel BCM model. The Nextel BCM was conducted in two steps. First, the atomistic structure was relaxed. Then, a nano-crack was introduced in the mullite/alumina interface and the structure was pulled under a uniaxial tensile load until failure occurred. The BCM results indicated a good match between the Nextel BCM model and the experimental results. The validated Nextel BCM model can be used for the structural analysis of fibers. [ABSTRACT FROM AUTHOR]

The open source introduction of fused filament fabrication (FFF) enables distributed manufacturing of consumer products. However, with a wide range of low-cost FFF 3-D printers and settings possible, there is a lack of information on the variability in printed mechanical properties. This paper utilizes a large pool of 47 user-assembled 3-D printers to quantify the mechanical property variations of ultimate tensile strength (UTS) and yield strength of FFF printed components using ASTM D638-14 horizontally-oriented Type I and IV geometries for poly lactic acid (PLA). The results indicate that utilizing Type IV tensile test piece geometry may overestimate the UTS relative to the Type I. Furthermore, anisotropic mechanical property variances were quantified for Type IV specimens (vertical and horizontal orientations). Vertical tensile specimens had an ultimate tensile strength 47.9% less than horizontal. Finally, the abundant supply of PLA 3-D prints suggest open-source printers assembled by individual operators can produce quality plastic components although the mechanical performance of the given part can vary dramatically based on the operator selection of printing parameters that provide a visually acceptable part. [ABSTRACT FROM AUTHOR]

Magnetic actuators, which use magnetic effects for actuation, are very useful in many areas, such as electrical equipment, soft robots, and medical instruments. However, they inevitably suffer damage during long-term use, leading to mechanical failure. Introduction of the self-healing concept can solve this problem to a certain extent and extend their service life. Herein, a room-temperature self-healing magnetic nanocomposite is obtained using a simple, efficient, and environmental-friendly strategy. In the authors' design, soft poly(dimethylsiloxane) (PDMS) polymeric materials are chosen as the matrix, and Fe3O4 nanoparticles are utilized as a functional magnetic nanofiller to obtain a new magnetic nanocomposite. By balancing the self-healing property and mechanical performance, the optimal content of magnetic filler is determined to be 15 wt%. The optimized sample exhibits an ultimate tensile strength (0.44 MPa), a high tensile strain (400%), and an excellent self-healing efficiency (62.2% mechanical recovery of fracture strength) at 25 °C for 30 min. Furthermore, this composite material shows an excellent and healable magnetic actuation performance. This new nanocomposite provides great potential for the magnetic actuation application. [ABSTRACT FROM AUTHOR]

• Adding nickel (Ni) and chromium (Cr) to Al6061/SiC composites enhances mechanical properties like strength and hardness. • The inclusion of Ni and Cr leads to increased yield stress, ultimate tensile strength, and flexural strength. • While there's a slight decrease in ductility, the trade-off results in improved material stiffness. • Overall, Ni and Cr show promise as effective reinforcements for engineering applications in Al6061/SiC composites. This research paper investigates the mechanical characteristics of Al6061/Nickel (Ni) and Al6061/Chromium (Cr) metal matrix composites (MMCs) with varying proportions of Ni and Cr by weight. The proportions of Ni and Cr range from 0% to 2.7% weight. Experimental results reveal that the optimum mechanical properties are achieved at 1.8% weight for Ni. Subsequently, SiC (silicon carbide) particles are added to Al6061/Ni MMCs at varying weight percentages (0%, 1%, 3%, 5%, and 7%) to evaluate their impact on performance. The study demonstrates that the combination of 1.8% Ni and 7% SiC in Al6061 exhibits the most favorable properties. Tensile test is carried out with ASTM D 3552 standard; Flexural strength is assessed through ASTM D790, Microhardness by ASTM E384, and Impact strength by ASTM D256. Overall, Al6061/Ni MMCs exhibit superior mechanical performance compared to Al6061/Cr MMCs, with Al6061/Cr MMCs excelling in elongation, flexural strength, and impact strength. This investigation confirms that the addition of nickel and chromium to the Al6061 alloy induces structural modifications that enhance its mechanical properties. The findings provide valuable insights for optimizing the design and fabrication of MMCs for various engineering applications. [ABSTRACT FROM AUTHOR]

Laser Directed Energy Deposition (LDED) additive manufacturing offers a versatile approach for fabricating composite materials, encompassing a wide range of heterogeneous and transition materials, known for their exceptional mechanical properties. In this study, we focus on the synthesis of TiN/TC4 sandwich structural materials in atmospheres characterized by varying nitrogen-to-argon ratios. This study includes the in-situ synthesis, microstructural evolution, and mechanical characteristics of these TiN/TC4 sandwich structures during the LDED process. Through this process, TiN was formed in-situ by the interaction of Ti and N atoms, exhibiting in robust metallurgical bonding with the TC4 matrix. Notably, the microhardness of the TiN/TC4 sandwich structures exhibits periodic variations along the deposition direction, ranging between 314.4 HV 0.2 and 661.5 HV 0.2. The tensile strength of the TiN/TC4 sandwich structures experiences significant enhancement, while maintaining toughness due to the laminate structure and reinforced with ceramic particles inside. The resulting sandwich composites demonstrate outstanding ultimate tensile strength, which can achieve 1123.3 ± 29.7 MPa. This represents a notable improvement of 20.3% over the TC4 deposited in a pure Ar environment, with a corresponding plastic strain of 2.5 ± 1.7%. This study demonstrates that layered heterogeneous materials with superior mechanical strength can be synthesized in-situ through flexible integration of LDED process and reaction atmospheres. [ABSTRACT FROM AUTHOR]

The gun barrel erosion caused by the burning of high energy propellants is becoming increasingly severe, significantly reducing the useful life of gun barrel. In order to address this problem, erosion reducing additives, including TiO 2 , paraffin, polyurethane or a combination of these, were introduced into the gun propellant or propellant charge system to alleviate the gun barrel erosion. In this article, a new type of flexible phase change composite materials (FPCMs) having excellent thermal stability and superior mechanical performance was successfully designed by incorporating paraffin/BN@PMMA (microPCMs) mixed with different binders of waterborne polyurethane (WPU), carboxylic butadiene-styrene latex (cBSL), and butadiene-styrene latex (BSL) on the fabric surface and applied as protective liners of cartridge case. Therein, the microPCMs was constructed with paraffin as the core and polymethyl methacrylate (PMMA) enforced by nano boron nitride (BN) as the shell by Pickering emulsion polymerization method. The morphology, chemical composition, and phase change behaviors of these prepared FPCMs were analyzed by SEM, FTIR, and DSC, respectively. Results show that these microPCMs with spherical structure but a little rough surface could be evenly distributed in the warp and weft structure of pristine fabric. The resulting FPCM sample containing WPU has the highest phase change latent heat of 38.77 J/g among these FPCMs. Additionally, TG and isothermal TG experiments reveal that the incorporation of binders has a positive effect on FPCMs thermal stability and FPCM sample containing cBSL exhibit the most remarkable thermal stability. The tensile experiments demonstrate that these FPCMs display the desirable mechanical performance and exhibit brittle fraction model. The tensile strength and elongation at break of FPCMs can be enhanced by the introducing of these binders. Pretreating pure fabric with gelatin is proved to be the most effective way in improving the mechanical performance of FPCMs. Herein, FPCM containing WPU has the highest ultimate tensile strength that can be up to 293.53 MPa. The novel flexible phase change composite materials could be a promising candidate to be used as protective liners to reduce the gun barrel erosion induced by the combustion of high energy propellants. [Display omitted] [ABSTRACT FROM AUTHOR]

2-D Cf/Mg composites consisting of AZ91D magnesium alloy and carbon non-woven fabrics are prepared by using the LSEVI process and their mechanical properties are experimentally tested. The experimental results show that the 2-D Cf/Mg composites have the better mechanical properties: elastic modulus of 71.0 GPa and ultimate tensile strength of 366.0 MPa, compared to AZ91D magnesium alloy matrix with the elastic modulus of 45.0 GPa and ultimate tensile strength of 250.0 MPa. The effective elastic properties of the 2-D Cf/Mg composites are numerically predicted by using a multi-scale homogenization method: the RVE based FE homogenization method at the macro-scale coupling the D-I mean-field homogenization model at the micro-scale. The agreement between the results of the experimental tests and the multi-scale homogenization method illustrates the validation of the multi-scale homogenization method to evaluate the effective mechanical properties of the 2-D Cf/Mg composites. For improving the computational efficiency, at the macro-scale the laminated composites theory is coupled with the RVE based FE homogenization method to predict the effective mechanical properties of the 2-D Cf/Mg composites. [ABSTRACT FROM AUTHOR]

CuO was coated on the surface of Al 18 B 4 O 33 whiskers by hydrothermal synthesis and CuO coated Al 18 B 4 O 33 whiskers reinforced 6061Al composites with different coating contents were fabricated by squeeze casting. The preparation process and characterizations of the CuO coated Al 18 B 4 O 33 whiskers were studied. The effects of CuO coating of whiskers on the microstructures, tensile properties and aging behaviors of the composite were investigated. The results showed that a uniform CuO coating of Al 18 B 4 O 33 whiskers could be prepared by hydrothermal synthesis. CuO reacted with molten 6061Al during squeeze casting and meanwhile a layer of continuous MgAl 2 O 4 formed at the interface. With increasing the contents of CuO coating on whiskers, the ultimate tensile strength of the composite gradually increased. The elongation to fracture of the composite initially increased and later decreased. Impressively, the ultimate tensile strength of the composite could be further improved after T6 heat-treatment. CuO coating of the whiskers could also obviously change the aging behaviors of the composite. [ABSTRACT FROM AUTHOR]

In situ 3.5 vol% TiBw whisker reinforced TiBw/TA15 composite with a novel network architecture was successfully fabricated by reaction hot pressing (RHP) method. In order to improve the high temperature mechanical properties of the composite, solid solution and aging treatments with different parameters were carried out. After sintering, the composite formed a net-like microstructure. The strength of composite was improved by the effect of whisker-rich boundary and the interconnected whisker-lean matrix retained its ductility. The elastic modulus and hardness of different phases were tested by nanoindentation for better understanding the strengthening mechanism. The ultimate tensile strength at 600–700 °C of the composite showed the highest value when the solution temperature is 1000 °C followed by aging treatment, which was caused by the distribution of a few residual primary α phases on the boundary and in turn the increasing of volume fraction for the reinforcements. Furthermore, the size and fraction of fine α+β phases increased with increasing of aging temperature after 1000 °C solid solution treatment, leading to the increasing of ductility and decreasing of strength for the composite tested at 600–700 °C. The above results showed that the composite with novel network architecture could be strengthened by heat treatments at high temperature environment, e.g. the ultimate tensile strength could be improved more than 200 MPa at 600 °C, and more than 100 MPa at 700 °C. [ABSTRACT FROM AUTHOR]

This study synthesized and characterized the Ti-48Al-2Cr-2 Nb-based composite reinforced by B 4 C addition, which was produced by spark plasma sintering. The grain size of composites decreased significantly from 225 ± 5 µm to 51 ± 5 µm with the increase of B 4 C content, mainly due to the pinning effect of in-situ generated TiB 2 and Ti 2 AlC particles at grain boundaries, which limited the rapid grain growth of the matrix. With the addition of B 4 C, the volume fraction of Ti 2 AlC increased from 3.0% to 7.4%, with an average size of approximately 5 µm. The ultimate tensile strength and total fracture elongation of the Ti-48Al-2Cr-2 Nb alloy were 482.9 MPa and 10.2% at 800 ℃, correspondingly. With 0.3 wt% addition of B 4 C, B 4 C/Ti-48Al-2Cr-2 Nb composite exhibited superior strength (579.5 MPa) and ductility (12.6%) at the same tensile temperature. The reinforced strength of the composite was mainly attributed to the grain refinement and precipitation strengthening. • B 4 C was able to react in-situ-react with the γ-TiAl to generate TiB 2 and Ti 2 AlC precipitates, which were distributed at grain boundaries, resulting in significant refinement of the grain size from 225.19 ± 5 µm to 51 ± 5 µm. • In-situ TiB 2 and Ti 2 AlC precipitates improved the microstructure stability of the B 4 C/Ti-48Al-2Cr-2 Nb composites. • High-temperature tensile strength and ductility of the B 4 C/Ti-48Al-2Cr-2 Nb composite were improved simultaneously under the synergistic effect of grain refinement and precipitation strengthening. [ABSTRACT FROM AUTHOR]

• The Ti 2 (Al,Si)C reinforced Al-Mg-Si composite is in-situ fabricated by spark plasma sintering method. • The composition of Al-Mg-Si matrix is effectively regulated by the addition of Si. • The Ti 2 (Al,Si)C/Al-Mg-Si composites demonstrate a ultimate tensile strength of 428 MPa and strain of 4%. The Ti 2 (Al,Si)C/Al-Mg-Si composite was fabricated by in-situ solid solution of Si to Ti 2 AlC during spark plasma sintering. The composition of Al-Mg-Si matrix alloy was effectively regulated by the addition of Si. The elemental distribution and atomic composition in Ti 2 (Al,Si)C particles and Al-Mg-Si alloy, as well as the microstructure of precipitated Mg 2 Si phase were carefully investigated. The composite after T6 heat treatment exhibits the ultimate strength of 428 MPa, yield strength of 358 MPa, and fracture strain of 4%. This research provides a novel method to balance the strength and plasticity of Al matrix composites. [ABSTRACT FROM AUTHOR]

Composites are well-known and widely used materials due to their anisotropic nature and high strength-to-weight ratio; therefore, the mechanical performance of these materials is crucial. Precise tensile testing is essential to obtain material properties that are crucial for the design stage of composite structures. This study is an effort to investigate the effect of adhesive materials used for tabbing process, which is necessary for the tensile testing procedure. Araldite and AF 163-2k film are used as the adhesive film, whereas in the case of AF 163-2k, tabbing is done through two different procedures (Jig and corner holes method). Apart from the tensile performance, strain distribution and damage progression are monitored simultaneously using digital image correlation (DIC) and acoustic emission (AE) analysis. It is observed that there is no significant difference in the ultimate tensile strength of these composites tabbed with different adhesives and procedures. Nevertheless, the first major failure strength is much higher in Araldite tabbed specimens compared to AF 163-2k film (the first major failure activity is defined as a point at which material loses its integrity, especially when considering structural or aerospace applications). Also, strain distribution throughout the gauge length recorded via DIC is appreciably different, which is attributed to damage accumulation and progression monitored by AE analysis. The frequency-based analysis of AE data is performed to classify the damage, and cumulative energy is correlated with the DIC to navigate the failure activity at different times and stress levels. • This study aims to understand the effect of tabbing adhesive and procedure on the mechanical performance and failure mechanisms of composite materials under tensile loading. • There is no significant difference in the ultimate tensile strength, but a remarkable difference has been observed in the first major failure event among the specimens tabbed with different adhesives. • Damage mechanisms are scrutinized through acoustic emission analysis, where several parameters are initially compared to each other to check their applicability for understanding damage progression. • The frequency-based analysis of AE data is performed to classify the damage, and cumulative energy is correlated with the DIC to navigate the failure activity at different times and stress levels. [ABSTRACT FROM AUTHOR]

The relatively low fabrication precision of CFRP (carbon fiber-reinforced plastics) is an obstacle to the bimaterial specimens' repeatability and reproducibility. A solution could be found by fabricating certain metallic specimens to fit the CFRP in order to obtain the exact experimental states of the bimaterial beam and accomplish the repeatability and reproducibility of the composite tests. The paper investigates the effect of spring-in distortion on a bimaterial beam's ultimate tensile strength by the designed experiments. Typical assembling process of the bimaterial beam containing spring-in distortion is analyzed. Bimaterial specimens are designed to represent the typical springin distortion. Tension tests are carried out based on available standards to determine the CFRP's behaviors in the numerical model. Correlation analysis between the real assembling state and the experimental assembling state is conducted in detail. Based on the verified numerical model of the experimental bimaterial beam, the numerical model of the real bimaterial beam is constructed. The effect of spring-in distortion on a bimaterial beam's ultimate tensile strength is obtained. The reported work presents a solution of fabricating certain metallic specimens to obtain the exact states of the bimaterial beam containing spring-in distortion. It will enhance the understanding of the composite components' assembly and help to systematically improve the composites' assembling efficiency in the civil aircraft industry. [ABSTRACT FROM AUTHOR]

In this study, mutiwalled carbon nanotubes (MWCNTs) were incorporated into low density polyethylene (LDPE) in different concentrations (2%, 4% and 8%) using a melt blending process. Structural, thermal stability and tensile property of the unirradiated/irradiated LDPE/MWCNT composites by 110 keV electrons were investigated by means of scanning electron microscopy (SEM), small angle X-ray scattering (SAXS), Raman spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, thermogravimetric analysis (TGA) and uniaxial tensile techniques. Experimental results show that the addition of MWCNTs obviously increases the ultimate tensile strength of LDPE and decreases the elongation at break, which is attributed to the homogeneous distribution of the MWCNTs in LDPE and intense interaction between MWCNTs and LDPE matrix. Also, the electron irradiation further increases the ultimate tensile strength of LDPE/MWCNT composites, which can be ascribed to the more intense interaction between MWCNTs and LDPE matrix, and the formation of crosslinking sites in LDPE matrix induced by the electron irradiation. The addition of MWCNTs significantly enhances thermal stability of the LDPE due to the hindering effect and the scavenging free radicals, while the electron irradiation decreases thermal stability of the LDPE/MWCNT composites since the structure of the MWCNTs and LDPE matrix damages. [ABSTRACT FROM AUTHOR]

Fatigue behavior of Sylramic-iBN/BN/CVI SiC CMC was investigated under tension-tension fatigue using a test facility which simulated simultaneously both loading and combustion conditions of hot-section components of gas turbine engines. Combustion environment was created using a high-velocity oxygen fuel gun to impinge combustion flame on one side of specimen subjected to fatigue to simulate the real situation. The flame-impinged surface of specimen was heated to average temperature of 1250, 1350, or 1480 °C. Ultimate tensile strength of CMC was about 270 MPa at 1480 °C under combustion environment. Fatigue life diagram was established at stress ratio of 0.1 and frequency of 1 Hz. The CMC survived up to 25 h at 46 and 33 % of ultimate tensile strength under combustion at 1250 and 1350 °C, respectively. However, it could not survive 25 h at 1480 °C under combustion fatigue environment even with no stress on the specimen due to degradation/erosion of the material. Microscopic analysis of fracture surface showed oxidation of BN interface, which was more on flame side than other side. Fracture surfaces showed oxide formation over matrix, fibers, and/or fiber/matrix interphase causing embrittlement and thereafter failure of CMC. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of the rheoformed parts of 7075 aluminum matrix composite were investigated. The results show that more liquid phase and spheroidal solid grains were found in the microstructures in the top and medium regions of the side wall of the rheoformed parts due to dependence of the deformation on liquid flow and flow of liquid incorporating solid grains. Yield strength and ultimate tensile strength of the rheoformed composite parts are enhanced as compared with the as-extruded and the rheoformed parts of 7075 matrix alloy. The yield strength, ultimate tensile strength and elongation of the rheoformed composite parts with T6 reach 399 MPa, 492 MPa and 9.6%, respectively. When stirring time increases from 5 min to 20 min, the mechanical properties increased due to fine-grained strengthening and a further increase more than 20 min led to a slight change. Pressure led to a significant increase of the mechanical properties due to some reduction of defects and dislocations strengthening. An increase of SiC volume fraction from 0.5% to 1% led to an improvement of yield strength and ultimate tensile strength and a further increase led to a decrease. [ABSTRACT FROM AUTHOR]

To address the weight and corrosion challenge in deep-water, replacing the steel tensile armour in flexible pipes with composite materials is an alternative conceptual approach. An axisymmetric structural responses model is built for this novel composite armoured flexible pipe, with interlayer gaps that may occur in the unbonded structure considered through an iterative algorithm. The tensile strength of steel and composite armoured pipes are predicted based on different constitutive relations of steel and composite. Essential quantities are obtained, such as tensile stiffness, deformations of each layer and interlayer gaps or contact pressures. Considering the helix form of carcass and pressure armour, a finite element model is established for the verification of the theoretical model. Case study shows that the tensile stiffness of flexible pipe is overestimated with the interlayer gap ignored. Compared with steel armoured flexible pipe, the composite armoured pipe, whose tensile stiffness decreases less as external pressure increases, meanwhile has higher values of tensile ultimate strength and torsion stiffness. Some suggestions about fiber types and volume fraction for composite tensile strips are given to ensure good performance of axial tensile strength and stiffness. • A theoretical model and a finite elements model are established to predict axisymmetric structural responses of composite tensile armored flexible pipes, and both results are in good agreements. • An iterative algorithm is used for solving the theoretical model which considers the possible gap in the adjacent layers. • The advantages of composite armored pipe in tensile stiffness and ultimate tensile strength are discussed and emphasized. • Some suggestions about fiber types and volume fraction for the composite tensile armours are presented. [ABSTRACT FROM AUTHOR]

This research presents the behavior of dombeya buettneri fiber/graphite hybrid composites which was studied to harness a favorable balance between the inherent advantages and disadvantages of natural and synthetic reinforcements. The fibers after extraction were chemically treated for surface modification. The composite was developed using compression molding process by randomly dispersing the reinforcements in the polypropylene matrix in predetermined proportions. The developed samples were tested to ascertain the response of the materials to the selected properties. Experimental results showed that hybrid composite sample C which is a blend of 12 wt% dombeya buettneri fiber (DBF) and 8 wt% graphite particle (GP) gave enhanced results in many of the properties which includes; hardness, impact, thermal insulation and abrasion resistance properties. Also, the hybrid composites sample denoted as sample E which is the blend of 6 wt% DBF and 14 wt% GP produce higher enhancement in the flexural properties and Young's Modulus of Elasticity than other samples. Composite sample reinforced with dombeya buettneri fiber as single reinforced composites performed more in ultimate tensile strength compared to other samples while graphite particle reinforced sample emerges as the best in thermal conductivity. Diffusion of water into the composites also obeys Fick's law where sample C was seen to be the best among the composites. It was therefore, discovered that the synergy between the two reinforcements has encouraged the improvement of polypropylene (PP) properties in a unique mode. [ABSTRACT FROM AUTHOR]

In recent years, graphene has attracted a great research interest in all fields of sciences due to its unique properties. Its excellent mechanical properties lead it to be used in nanocomposites for strength enhancement. In current work, a new magnesium-graphene nanoplatelets composite is fabricated for the first time using semi-powder metallurgy method. The effect of graphene nanoplatelets addition on the mechanical behaviour of pure magnesium under both tension and hardness is investigated. The results demonstrate that graphene nanoplatelets are distributed homogeneously in the magnesium matrix, therefore act as an effective reinforcing filler to prevent the deformation. Compared to monolithic magnesium, the magnesium/0.3 wt% graphene nanoplatelets composite exhibited improved elastic modulus, yield strength, ultimate tensile strength and Vickers hardness. The improvement in elastic modulus, yield strength (0.2%), ultimate tensile strength and Vickers hardness for magnesium/0.3 wt% graphene nanoplatelets composite relative to pure magnesium are up to +10.6%, +5%, +8% and +19.3%, respectively. In addition to tensile and hardness tests for the analysis of mechanical properties of as synthesized composite, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction are used to investigate the surface morphology, elemental percentage composition and phase analysis, respectively. [ABSTRACT FROM AUTHOR]

The objective of this present research study is to evaluate the mechanical characterization of composite materials, which were synthesized by a stir casting technique. AA6082 is chosen as matrix material and egg shell ash (ESA) particles as reinforcement. The base alloy and proposed composite specimens were subjected to hardness, tensile and wear test. Metallurgical characterization and worn surface of parent material and synthesized material were investigated by a scanning electron microscope (SEM). Mechanical properties like micro-hardness (HV) and ultimate tensile strength (UTS) of the developed composite materials were improved after the addition of reinforcement content. The microstructural changes in composites before and after inclusion of reinforcement is detailed in this article. Tribological behaviour of the composites was investigated by pin-on-disc machine. The test results exhibited that the AA6082-8wt% ESA AMCs have better tribological behaviour, when compared to the base aluminium matrix. [ABSTRACT FROM AUTHOR]

The problem of the biomass waste produced from palm oil plantation is present today. The biomass waste typically is sourced from oil palm trunk (OPT), oil palm frond (OPF) and oil palm fruit bunch. Considering the huge amounts OPF wood waste from palm oil plantation, the waste can have other added value if they can be used as in polymer composite materials. This study is subjected to investigate the effect of oil palm frond (OPF) fiber and powder loading to hardness, toughness, tensile and flexural strength of thermoplastic polyurethane (TPU) as wood polymer composite. Frond fiber with size of 2-3 mm and frond powder with size of 60-90 micron were used as filler materials. The TPU/OPF composite samples were fabricated by compressive molding approach. The result shows that hardness of TPU based composite increased by 48% with the addition of 30 wt.% of OPF powder. Ultimate tensile strength of TPU increased by 26% with addition of 30 wt.% OPF frond powder. The impact strength of TPU increased by about 50% by the addition of 30 wt.% of OPF frond fiber, while the flexural strength of TPU/OPF composites increased by about 86% by the addition of 30% OPF frond fiber. The microstructure of TPU/OPF composite samples shows good interfacial bonding between TPU matrix to OPF powder and OPF fiber, which represents a significant improvement of mechanical properties of TPU/OPF composites. It can be concluded that both, OPF powder and fiber addition significantly improved the mechanical properties of TPU. The OPF powder improved hardness and tensile strength, while the OPF fiber improved on the impact and flexural strength of the TPU. [ABSTRACT FROM AUTHOR]

New Al/SiC heteroparticles are investigated experimentally and theoretically. A composite material based on Al and SiC is predicted to exhibit a markedly higher tensile strength than pure Al due to the robust interface between Al and SiC. The theoretical predictions receive experimental confirmation. Specifically, incorporation of nano-SiC into the aluminum matrix to a level of 10 wt % is shown to increase the ultimate tensile strength of the resulting composite at room temperature to 317 MPa. [ABSTRACT FROM AUTHOR]

In the current research, the production of composites, characterization, mechanical and wear behavior of 5 and 10 wt.% of nano composites have been investigated by reinforcing the nano B4C ceramic particulates into Al2024 alloy. The composites were prepared by using two stage stir casting technique containing Al2024 alloy as a matrix phase and nano B4C particulates as reinforcement. After the composite preparation, the prepared composite material was examined by using various techniques such as SEM, EDS and XRD for characterizing the chemical elements and microstructures of reinforced and unreinforced material. Later, the mechanical properties and wear behavior of as cast Al2024 alloy and Al2024 −5 and 10 wt.% nano B4C composites were studied. Different mechanical properties such as hardness, percentage elongation, ultimate and yield strength were evaluated as per the ASTM standards. The dry sliding wear tests were conducted by using pin on disc equipment. The experiments were conducted for the sliding distance of 3000 m by varying the sliding speed and load. It was found that due to the addition of nano B4C ceramic particles in the Al2024 alloy matrix, the hardness, ultimate tensile strength and yield strength of the prepared composites were increased and the percentage elongation was decreased. Furthermore, there was an improvement in the volumetric wear loss with respect to the speed, load, and sliding distance for all the prepared composite materials. However, with the addition of nano B4C ceramic particulates in the base Al2024 matrix, the volumetric wear loss was decreased. The scanning electron microscope was used to study and analyze the fractography and different wear mechanisms for various test conditions of different compositions, tensile fractured surfaces and worn surfaces. [ABSTRACT FROM AUTHOR]