Volume Fraction Of Reinforcement Research Articles

Comparative investigation on microstructures and mechanical properties of (TiB + TiC)/Ti-6Al-4V composites from Ti-B4C-C and Ti-TiB2-TiC systems

Two percentages of TiB + TiC reinforced Ti-6Al-4V composites from Ti-B4C-C and Ti-TiB2-TiC systems were fabricated by reactive hot-pressed sintering. Their microstructures and mechanical properties involving elastic modulus, Vickers hardness, bending strength and wear property were investigated comparatively. The experimental results show that needle-like TiB whiskers and near-equiaxed TiC particles are evenly distributed in the Ti-6Al-4V matrix. The mechanical properties of the (TiB + TiC)/Ti-6Al-4V composites are closely related with the nominal composition and synthesis system of TiB + TiC reinforcement and the microstructures of composites. With increasing the nominal volume fraction of reinforcement, both elastic modulus and Vickers hardness increase more or less and the bending strength decreases in varying degrees. A certain increase of pores in the composites with the sintering temperature increasing to 1300 °C can markedly affect the bending strength. Moreover, no matter what the sintering temperature and nominal volume fraction of reinforcement, the elastic modulus and Vickers hardness of composites from the Ti-TiB2-TiC system are higher than those from the Ti-B4C-C system. Similarly, the composites from the Ti-B4C-C system present better abrasion resistance than those from the Ti-TiB2-TiC system due to the difference of interfacial bonding between the TiC particles and Ti-6Al-4V matrix in the two kinds of composites.

Low-velocity impact response of FG-GRC laminated beams resting on visco-elastic foundations

This paper presents an investigation on the low-velocity impact response of a functionally graded graphene reinforced composite (FG-GRC) laminated beam subjected to a transverse impact load. The beam is assumed to rest on visco-Pasternak foundations in thermal environments. Each layer of the laminated beam has the same thickness, but the volume fraction of graphene reinforcement for the layers may be different and vary along the thickness direction in a piece-wise functionally graded pattern. The temperature dependent material properties of graphene reinforced composites (GRCs) are estimated by an extended Halpin–Tsai model, where the graphene efficiency parameters are introduced and determined from the results of molecular dynamics (MD) simulations. The impactor that applies the impact load to the beam may act at any position of the beam for which the central impact is treated as a special case. The contact process follows a modified Hertz model. The linear motion equations of the FG-GRC laminated beam are established based on a higher-order shear deformation beam theory when the impact position is arbitrary, whereas the nonlinear motion equations are obtained only for the central impact case. The motion equations of the beam and the dynamic equation of the impactor are then solved simultaneously by the Runge–Kutta approach. The numerical results illustrate the influences of functionally graded graphene distribution, foundation stiffness, temperature variation and different impactor velocities on the central deflection of the FG-GRC laminated beam as well as the contact force between the beam and the impactor.

Direct and inverse multi-scale analyses of arbitrarily functionally graded layered hollow cylinders (discs), with different shaped reinforcements, under harmonic loads

A multi-scale model is proposed to investigate arbitrarily functionally graded hollow cylinders (discs), with fibers, particles, or disc-shaped reinforcements, subjected to harmonic loading conditions. The stress analyses are performed by dividing the cylinders (discs) into several layers each with homogeneous properties, which are functionally graded through the thickness of the structures, with varying microstructural details. Good agreement can be obtained by comparing the present stress distributions against other analytical solutions used as boundary conditions or obtained for homogeneous and continuously graded structures. Furthermore, the Mori-Tanaka model is used to generate effective properties of each layer reinforced with fibers, particles or disc-shaped inclusions. The stress distributions in the cylinders along the radial direction are effectively investigated with the influence of either the shape or the volume fraction of reinforcements. Finally, the particle swarm optimization technique is combined with the present framework to provide inverse calculations for microstructural details, in the effort of finding proper inclusion volume fractions or minimizing the shear stress along the radial direction, which are necessary for the design of functionally graded structures. The present analysis for arbitrarily FG cylinders under arbitrary loading conditions provides benchmark solutions for other future analytical and numerical methods.

Simulation of mushy state solidification in stir casting

PurposeStir casting is a promising technique used for the manufacture of Al-SiC metal matrix composites. The clustering of reinforcement particles is a serious concern in this production method. In this work, mushy-state solidification characteristics in stir casting are numerically simulated using computational fluid dynamics techniques to study the clustering of reinforcement particles.Design/methodology/approachEffects of process parameters on the distribution of particles are examined by varying stirrer speed, volume fraction of reinforcement, number of blades on stirrer and diameter ratio (ratio of crucible diameter to stirrer diameter). Further, investigation of characteristics of cooling curves during solidification process is carried out. Volume of fluid method in conjunction with a solidification model is used to simulate the multi-phase fluid flow during the mushy-state solidification. Solidification patterns thus obtained clearly indicate a strong influence of process parameters on the distribution of reinforcement particles and solidification time.FindingsFrom the simulation study, it is observed that increase in stirrer speed from 50 to 150 rad/s promotes faster solidification rate. But, beyond 100 rad/s, stirrer speed limit, clustering of reinforcement particles is observed. The clustering of reinforcement particles is seen when volume fraction of reinforcement is increased beyond 10 per cent. When number of blades on stirrer are increased from three to five, an increase in solidification rate is observed, and an uneven distribution of reinforcement particles are observed for five-blade geometry. It is also seen from the simulation study that a four-blade stirrer gives a better distribution of reinforcement in the molten metal. Decrease in diameter ratio from 2.5 to 1.5 promotes faster solidification rate.Originality/valueThere is 90 per cent closeness in results for simulation study and the published experimental results.

Characterization of Stir Cast Aluminium Silicon Carbide Metal Matrix Composite

Aluminium silicon carbide metal matrix composites (Al-SiC MMC) are gaining wider acceptance in various fields like aerospace, aircrafts, automobile, substrate in electronics, turbine blades, etc, due to their high strength, stiffness, high corrosion and wear resistance, good thermal and electrical properties and good damping capability. In this work Al-SiC MMCs are fabricated by mixing molten aluminium with Silicon carbide by the aid of mechanical stirring, called stir casting method. Also in this work, the stir casting process parameters are optimized within the range to obtain good mechanical characteristics and uniform mixing of reinforcement, which is a major concern in stir casting. The processing parameters that were investigated include stirrer speed, volume fraction of reinforcement, number of blades on stirrer and diameter ratio. Microstructure observed through optical microscope was correlated to clustering tendency of reinforcement particles. The results of mechanical characterization study and microstructure study show that the stirrer speed, volume fraction of reinforcement, diameter ratio, and number of blades on stirrer appears to have significant effect on mechanical properties and clustering tendency of reinforcement particles

Study on Mechanical Alloying of TiB<sub>2</sub> Particulate Reinforced Titanium Matrix Composites

TiB2 particulate reinforced titanium matrix composites were prepared by mechanical alloying and spark plasma sintering. Volume fraction of TiB2 powders in the composites are 5%, 10%, 15%. The effect of milling time and the volume fraction of reinforcement on microstructure and properties of the composites were studied. The results show that with increasing milling time, the size of powder particles decreases, quantity of them increases, and microstructure of the sintered samples becomes finer and more uniform. When milling time reaches 30h, the trend of powder agglomeration increases, the downward trend of the particle size becomes slowly. With the milling time, the density of titanium matrix composites is on the rise. The density of 10vol%TiB2 particulate reinforced titanium matrix composites can reach 4.799 g/cm3, with 30h milling time and sintering at 900°C. The density and hardness of the composites increase with increasing the volume fraction of TiB2. When the volume fraction of TiB2 is 15%, after milling 10h and sintered at 800°C, the density and hardness of the composites can reach 4.713g/cm3 and HV851.58.

Mechanical behavior of Al-matrix nanocomposites produced by stir casting technique

Aluminium matrix composites (AMCs) have emerged as a material for aircraft and automotive applications owing to its superior specific strength, stiffness, controlled co-efficient of thermal expansion, light weight and excellent wear resistance. The current research study emphases on the production of aluminium (AA6082) matrix composites reinforced in different volume fractions of alumina (50nm) particulates by using stir casting method. The volume fraction of reinforcement was varied from 0% to 3% in stages of 1%. The produced composites were examined by using scanning electron microscope (SEM). Hardness and tensile strength of the composite was studied. The mechanical properties of these composites were compared with matrix alloy. Microstructural results revealed the homogeneous distribution of nano alumina particles in the matrix. The test results revealed that the hardness and tensile strength of the composite increase with an increase in the volume fraction of alumina particle content, this may be due to good interfacial bonding between the reinforcement and the matrix.

Temperature effect on mechanical and tribological characterization of Mg–SiC nanocomposite fabricated by high rate compaction

In this paper, dynamic compaction is employed to produce Mg–SiC nanocomposite samples using a mechanical drop hammer. Different volume fractions of SiC nano reinforcement and magnesium (Mg) micron-size powder as the matrix are mechanically milled and consolidated at different temperatures. It is found that with the increase of temperature the sintering requirements is satisfied and higher quality samples are fabricated. The density, hardness, compressive strength and the wear resistance of the compacted specimens are characterized in this work. It was found that by increasing the content of nano reinforcement, the relative density of the compacted samples decreases, whereas, the micro-hardness and the strength of the samples enhance. Furthermore, higher densification temperatures lead to density increase and hardness reduction. Additionally, it is found that the wear rate of the nanocomposite is increased remarkably by increasing the SiC nano reinforcement.

Finite Element Analysis of Tool Particle Interaction, Particle Volume Fraction, Size, Shape and Distribution in Machining of A356/SiCp

The application of particulate reinforced metal matrix composite (PRMMC) has been increasing due to its superior strength and wear characteristics. The unique properties of PRMMC vary with respect to the volume fraction of reinforcement. In this paper a 2D Finite Element Analysis of A356/SiCp MMC during orthogonal turning is modelled and simulation is carried out using Abaqus as FE code. The main purpose of this study is to analyse the tool particle interactions and effect of volume fraction, size, shape and distribution during machining of A356/SiCp. In this model Lagrangian formulation approach is used. Johnson cook material model is employed for A356 and brittle cracking model is used for SiCp. Penalty contact method is used as the friction formulation with hard contact algorithm. The FE simulations are done for 0, 6, 12 and 15% of SiCp by volume, 60 and 12 micron of SiCp by size, circular & irregular shapes and uniform & irregular distribution of SiCp. The FE model created is validated with experimentally measured data, chip formation is simulated, tool-particle interaction is studied and effect of various volume fractions, sizes, shapes and distributions of SiCpin chip formation and stress pattern are analysed during the machining process using PCD tool insert.

Characterization of Glass Particulate Reinforced Aluminium Alloy6061 Metal Matrix Composites

In this paper an aluminum alloy Al6061- glass particulate metal matrix composites was prepared with different volume fraction of reinforcement 250 microns (3%, 6%, 9% and 12%) using melt stirring technique. The particle distribution in the prepared composites is observed using optical microscopy and XRD analysis. The prepared composite specimens were subjected to mechanical tests like hardness and tensile strength using Vickers hardness and uniaxial tensile testing instrument. It was observed from the results that the hardness and tensile strength increases with increase in wt% of reinforcement up to 9wt%. Hardness and tensile strength decreased for 12wt%.

Synthesis and Characterization of Aluminium Base in situ Metal Matrix Composites by Spark Plasma Sintering

Fe-aluminide and alumina reinforced in-situ aluminium based metal matrix composite was prepared by spark plasma sintering (SPS) of aluminium and nanosized Fe2O3 powder mixture. In-situ reinforcements were formed during SPS by exothermal reaction between aluminium and nano-size Fe2O3 particle. The thermal characteristics of the in-situ reaction were studied by differential scanning calorimetry (DSC). Field Emission Scanning Electron Microscopy (FESEM) along with the Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) techniques were used to study the microstructural architecture of the composites as a function of SPS temperature and the volume fraction of reinforcement. Microhardness measurement of the composite shows significant increase in hardness with increase in SPS temperature and volume fraction of secondary phase.

Dramatically enhanced impact toughness of two-scale laminate-network structured composites

TMCs are well known materials for their potential use in many fields. However, there are few research on the toughness especially impact toughness of TMCs. To improve impact property of TMCs, one novel kind of titanium matrix composites with two-scale laminate-network structure was fabricated via powder metallurgy and reaction hot pressing. From macro-scale, the novel composites were constituted by Ti6Al4V alloy layers and TiBw/Ti6Al4V composite layers. Moreover, the composite layer exhibited network structure and refined matrix microstructure from micro-scale. Layer thicknesses were well controlled by the masses of Ti6Al4V powder and TiB2-Ti6Al4V mixture powders, and the volume fraction of TiBw reinforcement in the composite layer was adjusted by controlling TiB2 raw material. Bending test results exhibited that the ultimate strain of two-scale composite doubled while bending strength was similar compared with TiBw/Ti6Al4V composites. The impact toughness of two-scale composites was nearly fivefold enhanced compared with monolithic TiBw/Ti6Al4V composites. This phenomenon can be attributed to the introduction of laminate structure, microstructure refinement and interface crack deflection. The analysis of impact curves and fractographs suggests that introducing Ti alloy layers can enhance plastic stage. Increasing TiBw reinforcement volume fractions can enhance the energy absorbed during crack propagation stage.

Strong, ductile, and thermally conductive carbon nanotube-reinforced aluminum matrix composites fabricated by ball-milling and hot extrusion of powders encapsulated in aluminum containers

Aluminum matrix composites reinforced by carbon nanotubes (CNTs) were fabricated by ball-milling (with aluminum powder; average diameter 30µm), followed by hot extrusion of the powders encapsulated in aluminum containers (at 550° with an extrusion ratio of 9). The CNTs were intended to improve the mechanical properties and thermal conductivity of the aluminum composites formed by powder metallurgy. The CNTs were of two types—vapor-grown carbon fibers (VGCFs) with a diameter of 150nm and multiwalled CNTs (MWCNTs) with a diameter of 65nm. The composites were evaluated by their Vickers microhardness, tensile strength, and thermal conductivity. The microhardness exceeded 100 HV and increased with increasing volume fraction of reinforcement. The MWCNT-reinforced composites were harder than the VGCF-reinforced composites and exhibited higher ultimate tensile strength (over 450MPa). The maximum fracture strain (37.2%, observed at a volume fraction of 0.5%) is the highest reported in the literature. Conversely, the VGCF-reinforced composites exhibited higher thermal conductivity than the MWCNT-reinforced composites. The thermal conductivity of the 0.5% VGCF-reinforced composites (203.7W/mK) also exceeds any previously reported value. In summary, composites with unprecedentedly high ultimate tensile strength, fracture strain, and thermal conductivity were fabricated by a simple process that minimized damage to the CNTs during mixing, protected them from oxidation and excessive reaction with the aluminum matrix and effectively densified composites by hot extrusion.

Microstructure of Polymer Composite Materials

This paper deals with problems connected with defects in polymer composite materials and the causes of their occurrences. The microstructure of polymeric materials with carbon and hybrid (carbon / aramid) reinforcement with an epoxy matrix is examined. The evaluation of the microstructures of the two types of composites was performed with the aid of a scanning electron microscope, as well as a 3D light microscope. Defects (dry spots, bubbles, pores,…) in the structure of the material significantly affect its properties, and the question of their elimination is also considered. In order to achieve the most favourable physical and mechanical properties, the production method for the composite materials is important. While preparing test samples, it was used manual lamination technology, where 45% volume fraction of fibre reinforcement could be achieved in the technological regularities.

Nonlinear vibration of functionally graded graphene-reinforced composite laminated cylindrical shells in thermal environments

This paper presents an investigation on the nonlinear vibration behavior of graphene-reinforced composite (GRC) laminated cylindrical shells in thermal environments. The material properties of the GRCs are temperature-dependent and the functionally graded (FG) materials concept is adopted which allows a piece-wise variation of the volume fraction of graphene reinforcement in the thickness direction of the shell. An extended Halpin-Tsaia micromechanical model is employed to estimate the GRC material properties. The motion equations for the nonlinear vibration of FG-GRC laminated cylindrical shells are based on the Reddy’s third order shear deformation theory and the von Kármán-type kinematic nonlinearity, and the effects of thermal conditions are included. The nonlinear vibration solutions for the FG-GRC laminated cylindrical shells can be obtained by applying a two-step perturbation technique. The results reveal that the nonlinear vibration characteristics of the shells are significantly influenced by the GRC material property gradient, the stacking sequence of the plies, the temperature variation, the shell geometric parameter and the shell end conditions.

Effect of ferrocement infill on the strength and behavior of RCC frames under reverse cyclic loading

An experimental study was conducted to investigate the strength and behavior of reinforced concrete (RC) frames with ferrocement infills. For this purpose, 1/4th scaled down model of one bay-three story frames were tested under reverse cyclic lateral loading. The ferrocement infill consists of hexagonal wire mesh with different values of volume fraction of mesh reinforcement viz. 0.20%, 0.30% and 0.40%. The strength and behavior of frames with ferrocement infill were compared with frame without infill. The experimental results indicated that the strength, stiffness, energy dissipation capacity and ductility of frames with ferrocement infill were significantly improved when compared with the bare frame. However, the increase in the volume fraction of hexagonal wire mesh of ferrocement infill showed only a marginal improvement in the strength and behavior of the infilled frame.

Effect of Volume Fraction of Reinforcement and Milling Time on Physical and Mechanical Properties of Al7075–SiC Composites Fabricated by Powder Metallurgy Method

The volume fraction of reinforcement and milling time are two important factors in fabricating aluminum metal matrix composites via powder metallurgy (P/M) techniques. In the present work, the effects of volume fraction of reinforcement and milling time on the microstructure, relative density, hardness, and compressive strength were studied. The Al7075 and SiC powders were mixed by a planetary ball mill for about 4 and 8 h, and Al7075–x vol.% SiC specimens (x = 4, 6, 8) were fabricated by a uniaxial cold press and sintered at 873 K (600°C) for 1 h. The crystallite size and morphology of the powder particles were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results showed that with increasing milling time and volume fraction of the reinforcement phase, the hardness and compressive strength increased. The SEM illustrates that the number of voids increases as SiC content increases, but their size decreases.

Investigation on the microstructure, room and high temperature mechanical behaviors and strengthening mechanisms of the (TiB+TiC)/TC4 composites

A hybrid of (TiB+TiC) reinforced Ti-6Al-4V (TC4) matrix composite was produced by solution ball milling and spark plasma sintering process. The reinforcements were uniformly dispersed into the β grain boundary of the TC4 matrix. The size of β-grain is markedly reduced from more than 300 μm to about 23 μm after adding 9.5 vol % reinforcements to the matrix. The room-temperature tensile test results show that yield strength of the composites was enhanced and eventually saturated with the addition of reinforcements. Among all the strengthening mechanisms, grain-refinement effect plays the most important role and contributes 58.5–76.3% increment of the room-temperature yield strength. TiC-particles contribute 15.9–32.2% and TiB-whiskers share the rest contribution. However, the existence of TiBw clusters weakens the load-bearing effect of TiB. The high-temperature yield strength of the composites was improved with increasing volume fraction of the reinforcements and decreased with increasing test temperature. The grain-refinement strengthening efficiency decreases with increasing temperature, while by contrast, the strengthening efficiency of TiC particles goes up. Owing to the combination effect of matrix softening and dynamic recovery process, no saturation of high-temperature yield strength is observed even when the maximum volume fraction of reinforcements (9.5 vol %) were added to the composites.

Effect of reinforcement volume fraction on the mechanical properties of the Al-SiC nanocomposite materials

Particle reinforced metal matrix composites (MMCs) has emerged as one of the potential materials for structural application due to their superior mechanical properties. However, these MMCs have poor damage tolerance due to their low fracture toughness. The volume fraction of reinforcement plays a significant role to improve the overall strength of the MMCs. In this research, Al matrix composites reinforced with three different volume fraction of the SiC nanoparticles were fabricated by a powder metallurgy process and the effects of volume fraction on the mechanical properties of the Al-SiC nanocomposite was investigated. The samples were prepared with 200 kN compaction load and 600°C sintering temperature. Subsequently, their mechanical testing was carried out. The density and hardness of the samples were investigated. Moreover, the microstructure of the nanocomposites was examined by optical microscope. The results showed that the high volume fraction reinforced nanocomposite exhibited better microstructural feature and high hardness as compared to the low volume fraction reinforced nanocomposite. Therefore, the high volume fraction reinforced nanocomposite can be a potential material to use in the brake disc of the automobile.

Mechanical performance of particulate-reinforced Al metal-matrix composites (MMCs) and Al metal-matrix nano-composites (MMNCs)

The metal-matrix composites/nano-composites (MMCs/MMNCs) reinforced with hard ceramic particulates have received a tremendous attention due to their potential improvements in physical and mechanical performances. In the present work, we have comprehensively collected currently available experimental data sets of Al-based MMCs/MMNCs and have carried out thorough analyses to quantitatively address the impacts of the reinforcement volume fractions, reinforcement particle sizes, and metal-matrix grain sizes on their mechanical properties including the yield strength, ultimate strength, and strain to failure of composites. We also performed a quantitative analysis on the strengthening mechanisms of Al MMNCs to reveal that the grain refinement can play a major role in increasing the strength of composites. Al-based MMC or MMNC materials generally exhibited an indirect relationship between the strength increase and strain-to-failure increase. The results include a critical comparison for the mechanical performance of particulate-reinforced composites for both pure and alloyed Al matrices to elucidate the contemporary status of Al MMC and MMNC materials.