Papers by Keyword: Volume Fraction

Abstract: The development of modern technology in microelectronics and power engineering requires the creation of efficient cooling systems. This is made possible by the use of special fin technology inside the cavity or special heat transfer Ethylene glycol-copper nanofluids to intensify the heat removal from the heat-generating elements. A numerical study of the natural convection of stationary laminar heat transfers in a closed rectangular cavity with a local source of internal volumetric heat generation. For different Rayleigh numbers and different volume fractions of nanoparticles. The system of equations governing the problem was solved numerically by the fluent computer code based on the method of finite volumes. Based on the Boussinesq approximation. Interior and exterior surfaces are maintained at a constant temperature. The study is carried out for Rayleigh numbers ranging from 10⁴ to 10⁶. The effects of different Rayleigh numbers and volume fractions of nanoparticles on natural convection have been studied. The results are presented as isotherms, isocurrents, and local and mean Nusselt numbers. The aim of this study is to see the influence of the thermal Rayleigh number and the volume fraction of the nanoparticles on the rate of heat transfer.

Abstract: Study of smart functionally graded (FG) beam made of carbon nanotube (CNT) reinforced composites combined with piezoelectric material is carried out. Material parameters of the beam are supposed to vary along its thickness following extended rule of mixture. Finite element model is developed for the functionally graded CNT reinforced beam combined with piezoelectric material using ANSYS software. Numerical results are evaluated using different boundary conditions. Computed results revealed that piezoelectric layer of smart FG beam efficiently controls the bending deformations of the presently studied smart CNT reinforced functionally graded beams. Results are also presented considering various material profiles for the grading of FG beams. It is observed that X type profile distribution considering CNT volume fraction of 0.28 provides minimum bending deflection of the presently studied smart FGCNT reinforced composite beams for the activated as well as inactivated piezoelectric material

Abstract: Cement, sand, aggregate, water and reinforcing bar are the materials in reinforced concrete, while a mixture without reinforcing bar is known as concrete. Concrete and reinforced concrete is the most widely used building material in the construction industry. Brittleness occurs when concrete is unable to withstand tensile loading, resulting in brittle failure. Moreover, fibre has the potential to improve the tensile strength of concrete. Due to this fact, steel fibre reinforced concrete (SFRC) exhibits superior resistance to cracking. It intends to increase the durability and decrease the crack deformation characteristics. This review article discusses the theoretical aspects of SFRC. Numerous references from both early and contemporary writers are included to help tie the subject together chronologically. This historical analysis aims to provide context for what is currently known about SFRC rather than to provide historical reporting. Hence, this paper discusses a review on the strengthening of reinforced concrete with steel fibre based on previous research before this.

Abstract: AbstractEpoxy syntactic foams (SF) filled with hollow glass microspheres (HGM) were prepared by simple resin casting method and characterization in this study. The effect of varying the amount of HGM on the specific mechanical and water absorption properties of SF composites were investigated. Five different composition of SF (SFT60-0.5 to SFT60-2.5) were compared with the neat epoxy matrix. The wall thickness of the microballoons differ because of its different percentile size distribution (10^th, 50^th and 90^th), which reflects in its density variation. The results show that the specific tensile and flexural strength increases with an increasing filler (HGM) content. The density of SF filled with HGM reduces with increasing volume fraction of filler content. Scanning electron microscopy was done on the failed samples to examine the fractured surfaces. The water absorption capacity of the SF was also investigated as it relates to the HGM volume fraction variation. All the syntactic foam composition shows a better diffusion coefficient capacity than the neat epoxy resin. This makes it applicable in structural purposes and several marine application products such as Autonomous Ultimately Vehicle (AUV).

Abstract: Magnesium oxide (MgO) nanoparticles were synthesized using the sol-gel technique then characterized. Cetyl Trimethyl Ammonium Bromide (CTAB) surfactant was added to reduce Van der Waal forces among MgO nanoparticles and distilled water forming a stable nanofluid using two-step method with aid of ultrasound sonication. Pure distilled water and nanofluids with different volume fractions of 0.25, 0.5, 0.75, and 1% are used as working fluids. Thermophysical properties of prepared nanofluids were measured experimentally and determined theoretically. Effect of solid volume fraction on the thermophysical properties; including thermal conductivity, heat capacity, viscosity, and density of MgO-water nanofluids are discussed. Moreover, experimental results have been compared with the suitable correlations for MgO-water nanofluid. The findings show that thermal conductivity, viscosity, and density of nanofluid increases with increasing solid volume fraction.

Abstract: Babbitt alloys are the most commonly used bearing materials for low speed diesel engines due to their excellent attributes. An understanding of microstructures in these alloys is important, especially quantifying microstructure in 3D. In this study, we used serial sectioning technique to reconstruct 3D microstructure of tin-based Babbitt lining of bimetallic bearing made by centrifugal casting based on medical software Mimics. The morphologies and volume fraction of hard phase particles and α-Sn matrix were obtained. The volume fraction of the reconstructed microstructures was verified by the area fraction of the metallographic sections, which proved a higher reliability of 3D reconstruction. The results of 3D microstructural characterization and analysis will enable a comprehensive understanding the structure–property relationships of these materials.

Abstract: This work deals with the experimental studies on effect of changing volume fraction and also various resin systems like Epoxy LY556, AW106 & CY230 on ultimate tensile, compression and flexural strength of a polymer matrix composite. The specimens were prepared through vacuum assisted resin transfer molding technique. The vacuum pump is a double stage rotary vacuum pump of specifications 300 lpm, 1 hp &3ph. Reinforcements of different thickness/layer of bidirectional e-glass fibers were used and the epoxy resins of varying viscosities were used. The machining of the fabricated specimens was carried out using abrasive water jet cutting facility. The test coupons were tested as per ASTM standards. Tensile, compression and flexural tests were carried out for each experiment and three trials were made for each experiment in order to arrive at the average value of tensile, compressive and flexural strength. The inferences are drawn for each type of resin system and volume fraction of the matrix and reinforcement used which helps in understanding the enhancement in ultimate strength of the test coupon under study.

Abstract: As a new type of material combined with special structure and function, the porous titanium was prepared through vacuum distillation and sintering process, by which the titanium powder was used as raw material, magnesium particles and its powder as space holder, anhydrous ethanol as binder. The porosity of porous titanium obtained by this method is between 35% and 75% and its opening ratio runs up to 95%. The experimental result showed that magnesium existed in the compacted precursor was evaporated rapidly in vacuum when temperature reached 750°C and removed completely within 20 minutes. The suitable sintering temperature was between 1050°C and 1250°C, but the porosity of porous titanium decreased from 76.2% to 61.3% with temperature elevated. The precursor uniformity was improved by addition of anhydrous ethanol and its formability and density was also done by addition of magnesium powder. The relative density of precursor increased from 82% to 98% with magnesium powder volume fraction varied from 30 vol.% to 80 vol.%.

Abstract: In this study, the modification effects and mechanism of manganese (Mn) and ultrasonic vibration (USV) on the needle-like Fe-containing intermetallic compounds of Al-20Si-xFe-2.0Cu-0.4Mg-1.0Ni (x=1, 2 wt.%) alloy have been studied respectively. The effect of Fe-containing phases on volume fraction of hard phases is also investigated. The results show that the mechanism and effect of Fe-containing intermetallic compounds improved by Mn are in close relationship with Fe content. Mn can promote to form less harmful α-Al₁₅(Fe,Mn)₃Si₂ phase, or replace some Fe atoms of β-Al₅FeSi and δ-Al₄FeSi₂ according to different Fe content. When USV was applied to this alloy containing 2%Fe near liquidus temperature, most of the acicular β phases formed in traditional process are substituted by fine plate δ phases. With the combined effects of 0.5%Mn and USV, the acicular β phases are almost repressed and the Fe-containing phases exist in form of fine Al₄(Fe,Mn)Si₂ and Al₅(Fe,Mn)Si particles about 20~30μm. Consequently, the total volume fraction of hard phases which are composed of primary silicon particles and Fe-containing phases increases significantly.

Abstract: Fiber reinforced laminate design is a challenging problem in the field of composite laminates. It provides us a systematic way to design the laminates of desired properties while conveniently incorporating the thick-ness and mass constraints. In this paper, we pursue the multivariate graphite fiber reinforced laminate design problem using Ant Colony Optimization (ACO) algorithm. Classical lamination theory is used to determine mid-plane strains, curvatures and stresses in individual lamina under applied biaxial loading conditions. The fiber orientations, lamina thickness, number of layers and fiber volume fractions of lamina are considered as the optimization variables. Failure of the lamina is analyzed by Tsai–Wu failure criterion. Objective of the study is to maximize the load carry capacity of the composite laminate structure and minimize the areal mass density under multivariate/multiobjective optimization.