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Automobile structural components are subject to high stress, friction and corrosive environmental conditions. Though aluminum alloys exhibit lightweight and high corrosion resistance, there is a need to improve the high strength-to-weight ratio and resistance to friction. This paper presents microstructural analysis, hardness, dry sliding wear behavior, and corrosion behavior of AA7075 reinforced with silicon carbide (SiC) particles. The composite specimens were prepared at the concentration of 2.5 and 5wt.% SiC. The microstructure of AA7075 showed dendritic morphology while composite specimens showed nondendritic morphology grains. Reinforcement of SiC resulted in increased nucleation site and refinement of grain during solidification. XRD analysis of base alloy showed $\alpha$ matrix with $\eta$ (MgZn₂), T(Al–Zn–Mg–Cu) and Al₇Cu₂Fe phases, while the composite sample showed the presence of additional S(Al₂CuMg) and $\theta$ (Al₂Cu) phases. Composite samples showed higher hardness values than base alloy due to grain boundary strengthening and Orowan strengthening. The enhancement of hardness of AA7075 by 20% and 37.5% were obtained with the addition of 2.5 and 5wt.% SiC particles respectively and also predicted with less coefficient of friction and less wear rate at all the tested load conditions. At the same time, the respective reduction in wear rates of AA7075 was found to be 50 and 65%. The worn-out surface of the base alloy was found to have undergone extensive plastic deformation and resulted in delamination with extensive patches and no clear groove marks. The composite sample of 2.5wt.% SiC showed mild patches with clear groove marks, while the Composite of 5wt.% SiC showed groove marks with fine width parallel to sliding directions. The wear mechanism was found to be transferred from adhesive mode to abrasive mode through a mixed mechanical layer with an added concentration of SiC particles from 0wt.% to 5wt.%. Weight loss during immersion corrosion increases with an increase in the amount of SiC due to an increased amount of metallic phase which increases microgalvanic corrosion and pitting. Hence, composite samples showed decreased corrosion resistance than base alloy.

The blades of helicopters and wind turbines undergo pitch motion in hygrothermal environments. Few works have studied the effect of this movement on blade frequencies. This paper focuses on the bending characteristics of a pitching thin-walled beam, including the effects of hygrothermal environments, rotor speeds, and composite materials. The harmonic pitch function is introduced into the dynamics model of a rotating beam. The method of multiple scales and the Galerkin method are used to solve these equations. Results indicate that the pitch amplitude A dramatically influences natural frequencies. Conclusions are obtained: (1) The flapping frequency varies periodically with pitch amplitude A, and monotonically changes every 2/$\pi$. The pitch amplitude A significantly impacts frequencies, while the pitch frequency ${\omega }_p$ and pitch phase C don’t influence frequencies. (2) An increase in temperature or humidity will decrease the flapping frequencies of a pitching beam. (3) The ply angle, coupled with the dynamic pitching angle, dramatically influences the flapping frequencies of the composite beam. The larger the ply angle, the greater the effect of pitch amplitude A on frequencies.

In this work, typical design, production, and testing procedures for a small unmanned helicopter are explained and performed. In doing so, preliminary sizing of the helicopter and three main disciplines are conducted: aerodynamic analytical and numerical simulations, power calculations, and structure analysis assessment. First, a thorough survey is implemented to obtain the trends for the maximum take-off weight versus some design constraints such as rotor diameter, motor power, payload, and empty weight. Performance calculation results are obtained to figure out all aspects that correspond to the specified mission. The designed rotor geometry along with the aerodynamic characteristics and flight performance variables is then validated using the blade element theory and numerical simulations. Second, based on the power curves obtained for different flight regimes, an electric brushless motor is selected. The numerical simulations (Computational Fluid Dynamics) analysis is used to enhance the selection which implies that the motor power should be greater than 5.4 kW to overcome the drag forces. The motor power selection corresponds to a maximum rotor pitch angle of 15^∘ and a maximum rotor speed of 1450 RPM. Then, the aerodynamic loads are used as an input for the structural analysis using one-way coupling of fluid–structure interaction (FSI) and consequently designing the internal structure of the blade. Eventually, the internal structure manufactured using carbon fiber-reinforced polymer (CFRP) by applying a combined technique between wet layup and compression molding. The blade is statically tested compared with numerical finite element model results. The fuselage structure along with hub and tail units is manufactured and assembled with the existing on-shelf components to examine the helicopter lift capability with different payloads up to 9 kg. The results show that the detailed design process is significant for manufacturing such blades and the helicopter is capable of lifting off the ground with various payloads depending on the rotor pitch angles (8^∘, 12^∘, and 15^∘) at a constant rotor speed of 1450 RPM.

A coupling-constant definition is given based on the compositeness property of some particle states with respect to the elementary states of other particles. It is applied in the context of the vector-spin-1/2-particle interaction vertices of a field theory, and the standard model. The definition reproduces Weinberg's angle in a grand-unified theory. One obtains coupling values close to the experimental ones for appropriate configurations of the standard-model vector particles, at the unification scale within grand-unified models, and at the electroweak breaking scale.

The aim of this study is to fabricate a high volume fraction B₄C-reinforced intermetallic matrix composite by the dipping exothermic reaction process and investigate the shock impact damage response of composites by explosive indentation experiment. It has been shown that the final microstructure of the dipping exothermic reaction process-fabricated composite can be tailored by treatment of the constituent powders and post heat treatment. The hardness and impact damage resistance of the fabricated composites were evaluated.

The results concerning the basic mechanical properties are presented for selected metal matrix composites (MMC). Three types of composites were produced by means of squeeze casting and next heat treatment. An influence of reinforcement type on the crack appearance in matrix and composite material was analyzed. Theoretical evaluation of the thermal shock resistance was proposed on the basis of conventional mechanical characteristics. Moreover, the qualitative metallographic investigations were carried out using optical microscopy method. A good consistence between the theoretical evaluation of thermal shock resistance and experimental data was achieved.

We have investigated magnetization, magneto-transport, and complex impedance spectroscopy of structurally characterized multiferroic composites xLa_0.7Sr_0.3MnO₃ (LSMO)–(1-x)ErMnO₃ (EMO) (0≤x≤1). Para- to ferromagnetic Curie temperatures for this series of composites indicate almost complete immiscibility within the mixture of those two compounds of LSMO and EMO having nearly identical chemical formula. Magnetization as a function of magnetic field curves at T=300 K exhibit an appreciable enhancement of coercive field of LSMO in the composites with increase in EMO content. This feature has been attributed to the increasing grain boundary pinning center of LSMO grains at their interfaces in the composites. Magneto-transport measurements reveal a considerable decrease in spin polarized tunneling transport with increase in EMO content in the composites. This feature is understood as a consequence of increasing grain boundary pinning centers of magnetic domains of LSMO grains in the composites. Room temperature complex impedance spectroscopy studies, i.e., -Z^′′ versus Z′ curves (Nyquist plots) for EMO, x=0.1, x=0.2, and LSMO samples reveal that relaxation time of both bulk and grain boundary increases with increase in EMO content in the composites. Slow relaxation processes of conduction electrons at both bulk and grain boundary occurs due to the proximity of highly resistive insulating EMO in the composites.

In this work, a series of ZrO₂/ZrW₂O₈ ceramic composites with different amounts of ZrW₂O₈ were successfully prepared by calcining the precursors synthesized using co-precipitation route at 1150°C for 3 h. The X-ray diffraction (XRD) data confirmed that the composites only consisted of α-ZrW₂O₈ phase and m-ZrO₂ phase. The scanning electron microscopy (SEM) analysis of the synthesized ZrO₂/ZrW₂O₈ composites showed that the specimens had good mixed-uniformities. In addition, the thermal expansion coefficients of the composites decreased with increased amounts of negative thermal expansion ZrW₂O₈, specimen with 26wt% ZrW₂O₈ shows almost zero thermal expansion and its average thermal expansion coefficient is -0.5897×10^-6K^-1 in the temperature range from 30°C to 600°C.

Magnetorheological (MR) suspensions, composed of colloidal particles dispersed in a carrier liquid, possess tunable rheological characteristics by applying an external magnetic field, showing dramatic changes of yield stress and shear viscosity caused by transformation between solid-like to liquid-like state. As a new MR material, we synthesized hollow polystyrene/magnetite (PS/Fe₃O₄) microspherical composite. Morphology of the PS obtained and the loaded magnetite were examined via SEM, and TGA spectra confirmed the composition. Magnetic property was tested by VSM data. MR characteristics of MR suspension based on PS/Fe₃O₄ composites were studied via both steady shear and oscillatory tests using a rotational rheometer equipped with a magnetic field generator.

When one cuts himself, it is amazing to watch how quickly the body acts to mend the wound. Immediately, the body works to pull the skin around the cut back together. The concept of repair by bleeding of enclosed functional agents serves as the biomimetic inspiration of synthetic self repair systems. Such synthetic self repair systems are based on advancement in polymeric materials; the process of human thrombosis is the inspiration for the application of self healing fibres within the composite materials. Results based on flexural 3 point bend test on the prepared samples have shown that the doubled layer healed hollow fibre laminate subjected to a healing regime of 3 weeks has a healed strength increase of 27% compared to the damaged baseline laminate. These results gave us confidence that there is a great potential to adopt such self healing mechanism on actual composite parts like in aircraft's composite structures.

A 304 stainless steel short fiber reinforced aluminum composite was fabricated and investigated for matrix voids as well as interfacial reaction using ultrasound. The aluminum composite was made by a hot isostatic pressing technique at a temperature of 600°C and subsequent aging at 120°C. The tensile strength significantly increased with the addition of 5% stainless steel fiber. The interfacial reaction evolved and grew with aging time due to generation of intermetallic FeAl₂. The ultrasonic nonlinearity (β/β₀) increased with the volume fraction of fiber and aging heat treatment because of the generation of microvoids resulted from localized fibers and matrix precipitation. This study demonstrates the potential for characterization of reinforced composite materials fabricated by the powder metallurgy technique.

The use of silicon-based ceramics and composites as combustor liners and turbine vanes provides the potential of improving next-generation turbine engine performance, through lower emissions and higher cycle efficiency, relative to today's use of super alloy hot-section components. As a series of research for FOD resistant, a particle erosion wear test was carried out for continuous Pre-SiC fiber-reinforced SiC matrix composites with a new concept of lab. scale fabrication by LPS process. The result shows that aperture (some form of porosity) between fiber and interface has a deleterious effect on erosion resistance. Aperture along the fiber interfaces consequently causes a severe wear in the form of fiber detachment. Wear rate increase proportional as contents of open porosity increases. For nearly full dense composite materials of about 0.5 % porosity, are about 200 % more wear-resistant than about 5 % porous composites. Grain growth and consolidate condition of matrix which directly affects to FOD resistant are also discussed.

Cross-Linked Polyethylene (XLPE) is widely used as insulation in electrical engineering, especially as cable insulation sheaths. In order to improve the dielectric properties susceptible to be modified under the effects of thermal aging and water in an absorption environment, polymers are mixed with ceramics. In this paper, the influence of barium titanate (BaTiO₃), on the dielectric properties of XLPE has been studied. Dielectric parameters have been measured using an impedance analyzer RLC (WAYNE KERR 6420 type). Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy and X-ray diffraction were used as characterization techniques. The study has been carried out on two samples of XLPE. A pure sample of each were studied as a unloaded samples to be compared with samples of 5%wt, 10%wt, 15%wt and 20%wt. BaTiO₃ loaded XLPE. Afterwards, the composites were subject to humidity and to thermal aging. The incorporation of BaTiO₃ 1${}^{\circ }$C does not modify the crystallinity and morphology of the XLPE and 2${}^{\circ }$C reduces the space charges therefore the dielectric losses. $tg\delta$, ${\epsilon }_r$ and loss index are measured. Frequency response analysis has been followed in the frequency range (20–300 Hz). Experimental results show well that BaTiO₃ as nano-filler improves the dielectric properties of XLPE but in excessive content can drive to the cracking and therefore to absorption of water.

Magneto tunable left-handed material (LHM) which acts as a composite system has been theoretically demonstrated. The variation of the real and imaginary parts of the effective refractive index of the system is studied. The resonance that occurs in these studies are analyzed. The variation of impedance, reflectivity, absorptivity with frequency of the composite system was observed. The changes in resonance frequency with applied magnetic field are investigated. It is found that the resonance frequency increases with applied magnetic field.

Water line purification and wastewater treatment have become challenging in the fast-growing industry, infrastructure, textile, manufacturing world, etc. with this challenge, photocatalysis has gained substantial attention as an environmentally friendly process on which researchers are working aggressively and, in this progress, two-dimensional (2D) are in focus because of their good photocatalytic ability. Therefore, in this study, we present the synthesis of one such ternary composite material comprising molybdenum trioxide nanorods (MoO₃NR), reduced graphene oxide (rGO) and gold nanoparticles (AuNR), with a specific focus on its enhanced photocatalytic performance. The ternary composite is prepared via a combination of in situ hydrothermal and laser ablation methods allowing for precise control over the growth and integration of the constituent materials. The structural and morphological properties of the MoO₃ nanorods, rGO and Au ternary material were systematically characterized using various techniques, including UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The obtained results suggest the successful formation of a composite, revealing the presence of uniformly dispersed MoO₃ nanorods on the rGO sheets and evenly distributed Au nanoparticles throughout the structure. Photocatalysis evaluations conducted to assess the material performance under visible light irradiation exhibited significantly enhanced methylene blue degradation efficiency of 85.91% in 90min in comparison with individual MoO₃ nanorods and rGO counterparts. The improved efficiency can be attributed to the combined effects arising from the integration of MoO₃ nanorods, rGO and Au nanoparticles, which facilitate efficient light absorption, charge separation and catalytic reactions, which in turn reduces electron–hole recombination and improve photocatalytic performance. Also, the tunable morphology and collective effects of MoO₃ nanorods, rGO and Au offer new avenues for designing highly efficient and stable photocatalytic materials.

Ferroelectric ceramics are highly desired for applications in energy storage devices due to their fast charge-discharge capability. However, electric field-driven gradual degradation of ferroelectric polarization (i.e., fatigue) inevitably results in a decrease in energy efficiency and energy storage density. Therefore, improving fatigue endurance is one challenge for their practical applications in energy storage devices. Here, we provide a strategy to modulate the strain response to the external electric field, and thus, increase the fatigue endurance by employing hybrid improper ferroelectricc Ca₃Ti₂O₇ ceramic that exhibits a negative piezoelectric effect. We synthesized $(1-x)$ BaTiO${}_3-x$ Ca₃Ti₂O₇ (BT-xCT) ceramics, in which the strain response of ceramics to the electric field gradually decreases with the increasing proportion of Ca₃Ti₂O₇. For BT-0.3CT ceramic, the energy density storage efficiency is improved to 74.95% which is much higher than that of BT-0.1CT (48.07%). The strain response to the external electric field of BT-0.3CT is substantially lowered and almost reaches zero, leading to excellent fatigue endurance ability. This research work paves a route for designing ferroelectric ceramics with smaller strain response and enhanced fatigue endurance ability, which is expected to benefit a wide range of applications of ferroelectric ceramics in various electric capacitors and electric storage devices.

This experiment chooses A356 aluminum matrix composites containing 55% SiC particle reinforcing phase as the parent metal and Al–Si–Cu–Zn–Ni alloy metal as the filler metal. The brazing process is carried out in vacuum brazing furnace at the temperature of 550°C and 560°C for 3 min, respectively. The interfacial microstructures and fracture surfaces are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy spectrum analysis (EDS). The result shows that adequacy of element diffusion are superior when brazing at 560°C, because of higher activity and liquidity. Dislocations and twins are observed at the interface between filler and composite due to the different expansion coefficient of the aluminum alloy matrix and SiC particles. The fracture analysis shows that the brittle fracture mainly located at interface of filler and composites.

The tungsten fiber reinforced titanium composite (W/Ti) was produced by the spot welding method. The internal stress alteration of the W/Ti composite was measured by the neutron diffractometer, DN1, which had been installed at beam port #6 in National Nuclear Energy Agency Indonesia. The two-dimensional detector and cryostat system were mounted on the DN1 diffractometer, and the residual stress alterations were measured by the in situ neutron stress measurement technique under the cooling cycles from 300 K to 10 K. Residual stresses in tungsten fiber were investigated at several temperatures. In the longitudinal fiber direction, the thermal residual stresses of tungsten fiber became a large compressive state and represented the maximum value is about -950 MPa. The calculated results of the simple elastic model agreed with the experimental results of the in situ thermal stress measurement qualitatively. It is assumed that the stresses in the fiber longitudinal direction are the dominant stresses in the W/Ti composite.

The charge-trapping memory devices namely Pt/Al₂O₃/(Al₂O${}_3{)}_{0.5}$(Cu₂O)${}_{0.5}$/SiO₂/$p$-Si with 2, 3 and 4 nm SiO₂ tunneling layers were fabricated by using RF magnetron sputtering and atomic layer deposition techniques. At an applied voltage of ±11 V, the memory windows in the C–V curves of the memory devices with 2, 3 and 4 nm SiO₂ tunneling layers were about 4.18, 9.91 and 11.33 V, respectively. The anomaly in memory properties among the three memory devices was ascribed to the different back tunneling probabilities of trapped electrons in the charge-trapping dielectric (Al₂O${}_3{)}_{0.5}$(Cu₂O)${}_{0.5}$ due to the different thicknesses of SiO₂ tunneling layer.

Voids or porosities have been one of the biggest headaches in composite fabricators and are still a challenging issue. In this study, void behavior in a low pressurized area of the laminate during cure is identified and analyzed. And, the influence of material’s cure rate difference on laminate inner quality is evaluated and verified through material evaluation and test article fabrication with subsequent non-destructive and destructive inspection. When there is a surface film on outer layer of the laminate, it is confirmed that surface film acts as barrier layer to prevent void evacuation and keep voids locked in laminate during cure. And, under the same fabrication condition and process variables, except for a layer of surface film, trapped void have been properly evacuated and test article exhibited good inner quality.