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A comparative study between conventional and improved retting of jute (Corchorus olitoriusL. and C. capsularisL.) with a talc based microbial formulation was carried out for three consecutive retting trials in the same water during 2014. Due to introduction of the microbial formulation consisting of three different strains of Bacillus pumilusin the improved method, retting duration reduced by 6–7 days, fibre recovery increased by 9.7–12%, with the improvement in fibre quality (colour, lustre, fibre strength etc.) as compared to conventional method. The net return of farmers also increased by Rs. 13,490 ha−1over conventional retting. Moreover, the root content which is not desirable for quality fibre production was high (16–20%) in conventionally retted fibre as compared to fibre obtained from improved retting (3–4%). The polygalacturonase (3.6–5.3 IU ml−1), pectin lyase (142–185 IU ml−1) and xylanase activities (5.2–7.5 IU ml−1) recorded in retting water after each retting of improved method was higher by more than 2 times as compared to conventional one. These higher enzymatic activities in the retting water resulted in reduced retting duration and improvement in fibre recovery and quality. Further, the quality jute fibre extraction from repeated retting in the same stagnant water was possible by using the highly efficient microbial formulation. This technology has the potential to meet the demand of quality jute fibre by jute industries and also to increase the net income of resource poor jute farmers with meagre initial input.

2D numerical simulation of planar flow melt spinning process was accomplished employing transient analysis of fully coupled fluid flow and heat transfer using CFD software—Ansys Fluent. Fe–B–Si alloy was chosen as the candidate alloy. In the PFMS process, the molten alloy flowed from a crucible through a nozzle slit onto a rotating copper wheel, where a puddle was formed and from which a continuous amorphous ribbon was spun. The objective of the investigation was to examine the melt flow through the crucible nozzle slit on the melt puddle formation and its stability over time as a function of: (a) the effect of gas ejection pressures taken between 0.1 and 0.35 kg/cm2; (b) the nozzle slit widths ranging from 0.3 to 0.5 mm; and (c) the amount of alloy used which was 0.5 kg. Herein, the dynamics of the development of the puddle immediately after melt ejection, the stability of puddle, the ribbon thickness, puddle oscillation and temperature distribution were examined. Simulations indicate that the puddle lengths and ribbon thickness were found to increase linearly with increase in gas ejection pressure; pinning of the liquid puddle at the nozzle edge was found for low gas ejection pressure which caused continuous air entrapment leading to defective amorphous strips. Heat transfer characteristics were also investigated.

A microbial consortium consisting of three bacterial strains isolated from jute retting water with very high polygalacturonase (PG) (5.1–6.0 IU/ml), pectin lyase (PNL) (185.7–203.7 U/ml), xylanase (15–16.2 IU/ml) activity, but devoid of any cellulase activity was used for jute and mesta retting under controlled and farmers’ field conditions. The three isolates were identified as different strains of Bacillus pumilus, which were designated as PJRB1, PJRB2 and PJRB3 by ribotyping of a 977 bp fragment. The three strains, when used in a consortium mode, showed enhanced enzymatic activity and in a 1:2:1 ratio produced maximum activity of PG (21.7 IU/ml), PNL (238.0 U/ml), xylanase (15.8 IU/ml). Whole plant retting of jute and mesta with microbial consortium under controlled conditions reduced the retting duration by 7 days for jute, with improved fibre quality i.e. colour, lustre, fibre strength (27.0–28.1 g/tex, fineness (2.7–2.8 tex) and fibre recovery by 13.8–15.24 % over control.

In this paper, we report the effect of partially replaced Nb on glass forming ability (GFA), structure and soft magnetic properties in Fe86Zr7−xNbxB6Cu1(x = 0 and 3.5 at.%) melt spun ribbons, processed at different cooling rates by varying wheel speeds. Decreasing the wheel speed, the structures of both alloys change from complete amorphous to partial amorphous then to complete crystalline phase. It has been found that the Nb enhances GFA which is also confirmed through thermodynamically calculated PHSSvalues. The annealing of completely amorphous ribbons of both compositions, processed at a wheel speed of 47 m/s leads to the formation of α-Fe phase in amorphous matrix and enhances soft magnetic properties.

Abstract: The present investigation deals with the processing of rapidly solidified 10–40 mm wide, 30–50 μm thick and 10–30 m long continuous amorphous ribbons of Fe–Si–B–Nb–Cu alloy using a planar flow melt spinning (PFMS) equipment. As the formation of quality amorphous ribbon depends on the melt puddle formed between the nozzle and the rotating copper wheel, the effect of different processing parameters such as nozzle wheel gap, ejection pressure etc. on the shape and stability of puddle has been studied using a high-speed imaging system and correlated with ribbon formation. Simultaneously, a two-dimensional numerical model has been developed to simulate the puddle formation during the PFMS process. The model is based on a computational fluid dynamics technique, called volume of fluid using transient heat transfer and fluid flow equations with the evolution of free boundaries. Different simulations have been performed to study the effect of process parameters on the puddle formation. The simulated results have been verified with the experimental observations considering same set of process parameters. It has been observed that the present simulations have produced exact replica of the experimental observations. Further parametric analysis as well as analysis of simulated result has been carried out to understand how the different process parameters affect the formation of quality amorphous ribbons during PFMS process.

Amorphous ribbons of composition Fe68.5Cu1Nb3Si18.5B9 were produced by melt spun unit. Positron annihilation technique along with DSC and XRD studies has been employed to characterize the nanocrystallization process. XRD results confirmed presence of Fe3Si and Fe2B phases. Two life time components could be fitted to life time spectra of amorphous and heat treated samples. Life time of positron in amorphous matrix was found to be 163.3 ps. Small life time components in nanocrystallized samples could be ascribed to positron annihilation within amorphous and nanocrystalline particles. Larger life time component could be attributed to positron annihilation in interfaces associated with primary and secondary phase particles.

Abstract: Crystallization behaviour and magnetic properties of melt-spun Fe-Si-B-Nb-Cu alloys have been investigated. It is found that the primary phase changes from α-Fe(Si) to Fe3Si (DO3) on increasing the Si content The coercivity of the alloys containing the Fe3Si phase is significantly lower as compared to the alloy containing α-Fe(Si) phase. A heat treatment temperature-time-coercivity map has been obtained for optimization of the coercivity.

The summer of 2002, of course, saw the successful hosting of the FIFA World Cup in Asia, and the autumn of 2002 saw the equally successful Asian Games. Sport in the Global Society and The International Journal of the History of Sport celebrate both these events and Asian's notable involvement in modern sport with a number of contributions on Asia. This celebration has already begun with the publication of Sport in Asian Society: Past and Present edited by J.A. Mangan and Fan Hong. Other volumes on China and Japan respectively will follow shortly. This Review Essay by Boria Majumdar is part of the Cass Sports Studies' timely focus on Asia in recognition of its notable success on sports fields and in sports arenas in the twentieth century and the early twenty-first century.

In the analysis of hydrodynamic journal bearings the effect of fluid inertia is usually ignored in view of its negligible contribution compared to viscous force. However, the fluid inertia effect is to be taken in the analysis when modified Reynolds number is around one.Flexibly supported journal bearings are in general more stable when support design is proper. The aim of this paper is to see if there is any effect of fluid inertia on flexibly supported journal bearings. The mass parameters (measure of stability) are estimated for different support parameters and modified Reynolds numbers by adopting a non-linear time transient analysis.

Abstract: A combined experimental and computational methodology was used to determine the relevant strength and residual-stress parameters in a manufactured, high-fiber-volume-fraction multiply metal matrix composite (MMC). The method was similar to that previously demonstrated on single-fiber composites, which had an extremely low fiber volume fraction. Variabilities in residual stresses and debond strengths in high-fiber-volume-fraction multiply composites, as well as current demands on the micromechanics-based computational prediction and validation of complex composite systems, necessitated the establishment of the test methodology described here. The model material chosen for this investigation was a plasma-processed six-ply, unidirectional Sigma-1240/Ti-6Al-2Sn-4Zr-2Mo (wt pct) MMC containing 32 vol pct continuous fibers. Room-temperature transverse tensile experiments were conducted on cruciform specimens. In addition, rectangular specimens were also evaluated in order to verify their applicability in obtaining valid interfacial property data. Debonding events, evaluated at different positions within a given specimen geometry, were captured by stress-strain curves and metallographic examination. Analytical and finite-element stress analyses were conducted to estimate the geometrical stress-concentration factors associated with the cruciform geometry. Residual stresses were estimated using etching and computational procedures. For the cruciform specimens, the experimental fiber-matrix debond strength was determined to be 22 MPa. Separation occurred within the carbon-rich interfacial layer, consistent with some previous observations on similar systems. Thus, the cruciform test methodology described here can be successfully used for transverse interfacial-property evaluation of high-fiber-volume-fraction composites. For the rectangular specimens, the strain gages at different positions along the specimen width confirmed that the interface crack had initiated from the free edge and propagated inward. Hence, rectangular specimens cannot be used for valid interface strength measurements in multiply composites.

Abstract: The solidification morphology of the Zn-Bi monotectic alloy is studied through directional solidifcation processing. It is shown that the aligned growth depends on the crystallography of the solid-liquid interface. The best alignment of the monotectic liquid phase (L 2) occurs when the growth direction is [0001]Zn followed by that of [10 $$\bar 1$$ 0]Zn. Aligned growth could not be observed in other growth directions. A parametric approach is adopted, which incorporates the mechanical stability of the three phases at the growing interface and Derby and Favier’s criterion for monotectic growth, derived from Jackson and Hunt theory of coupled growth, to identify the possible window of growth conditions and phase spacings where aligned growth is possible.

Non-linear transient stability analysis has been performed to study the sub-synchronous whirl stability of a rigid rotor supported on two symmetric hydrodynamic bearings with rough surfaces subjected to a unidirectional constant load. A Reynolds type equation for finite hydrodynamic bearings, with different models of rough surfaces, has been solved using the stochastic finite element method. The trajectories of the journal center have been obtained by solving the equations of motion of the journal center by the fourth-order Runge-Kutta method. Results show an increase in the stability with transverse roughness and a decrease in the stability with isotropic roughness. A small improvement in stability is obtained with longitudinal roughness.

Mechanical tests were performed on a powder-metallurgically processed 7093/SiC/15p discontinuously reinforced aluminum (DRA) composite in different heat-treatment conditions, to determine the influence of matrix characteristics on the composite response. The work-hardening exponent and the strain to failure varied inversely to the strength, similar to monolithic Al alloys, and this dependence was independent of the dominant damage mode. The damage consisted of SiC particle cracks, interface and near-interface debonds, and matrix rupture inside intense slip bands. Fracture surfaces revealed particle fracture-dominated damage for most of the heat-treatment conditions, including an overaged (OA) condition that exhibited a combination of precipitates at the interface and a precipitate-free zone (PFZ) in the immediate vicinity. In the highly OA conditions and in a 450 °C as-rolled condition, when the composite strength became less than 400 MPa, near-interface matrix rupture became dominant. A combination of a relatively weak matrix and a weak zone around the particle likely contributed to this damage mode over that of particle fracture. Fracture-toughness tests show that it is important to maintain a proper geometry and testing procedure to obtain valid fracture-toughness data. Overaged microstructures did reveal a recovery of fracture toughness as compared to the peak-aged (PA) condition, unlike the lack of toughness recovery reported earlier for a similar 7XXX(Al-Zn-Cu-Mg)-based DRA. The PA material exhibited extensive localization of damage and plasticity. The low toughness of the DRA in this PA condition is explored in detail, using fractography and metallography. The damage and fracture micromechanisms formed the basis for modeling the strength, elongation, toughness, and damage, which are described in Part II of this work.

In this article, the tensile and fracture properties of a discontinuously reinforced aluminum (DRA) alloy composite are modeled to determine the influence of constituent parameters on material behavior. Comparison of the elastic-modulus calculations to the experimental data suggest that the angular particles are more effective in load transfer than spherical particles, and that a unit cylinder geometry is a good representation of the particles under elastic conditions. This same geometry is used in the finite element-based elastic-plastic model of Bao et al., and reasonably good agreement is obtained between the experimental and predicted yield strengths. A fracture-mechanics model is proposed for predicting the elongation to failure. The model assumes the existence of particle cracks, and criticality is based on the strain required for matrix rupture between cracked particles. The damage criterion of Cockcroft and Latham is utilized, and model predictions are compared to data from different investigations. It is shown that the volume fraction of particles and the work-hardening coefficient of the matrix have a strong influence on the strain to failure. Fracture toughness modeling once again exposes the limitations of existing zero-degree crack-propagation models, such as that of Hahn and Rosenfield, which predict increased toughness with yield strength rather than a decrease, which is observed experimentally. A shear-failure model along a 45-deg direction is proposed for the higher-strength conditions, where concentrated slip bands were observed. The model exhibits the inverse toughness dependence on strength and better correlation to peak-aged (PA) data, but shows poorer agreement with underaged (UA) data. Thus, a transition from zero-degree propagation to 45-deg propagation with increasing strength is suggested. A simplified method for extracting particle stresses is illustrated and is used to estimate a Weibull modulus of 4.9 and a Weibull strength of 2450 MPa for the SiC particles of an average diameter of 10 µm.

In this article, the tensile and fracture properties of a discontinuously reinforced aluminum (DRA) alloy composite are modeled to determine the influence of constituent parameters on material behavior. Comparison of the elastic-modulus calculations to the experimental data suggest that the angular particles are more effective in load transfer than spherical particles, and that a unit cylinder geometry is a good representation of the particles under elastic conditions. This same geometry is used in the finite element-based elastic-plastic model of Bao et al., and reasonably good agreement is obtained between the experimental and predicted yield strengths. A fracture-mechanics model is proposed for predicting the elongation to failure. The model assumes the existence of particle cracks, and criticality is based on the strain required for matrix rupture between cracked particles. The damage criterion of Cockcroft and Latham is utilized, and model predictions are compared to data from different investigations. It is shown that the volume fraction of particles and the work-hardening coefficient of the matrix have a strong influence on the strain to failure. Fracture toughness modeling one again exposes the limitations of existing zero-degree crack-propagation models, such as that of Hahn and Rosenfield, which predict increased toughness with yield strength rather than a decrease, which is observed experimentally. A shear-failure model along a 45-deg direction is proposed for the higher-strength conditions, where concentrated slip bands were observed. The model exhibits the inverse toughness dependence on strength and better correlation to peak-aged (PA) data, but shows poorer agreement with underaged (UA) data. Thus, a transition from zero-degree propagation to 45-deg propagation with increasing strength is suggested. A simplified method for extracting particle stresses is illustrated and is used to estimate a Weibull modulus of 4.9 and a Weibull strength of 2450 MPa for the SiC particles of an average diameter of 10 μm.

Mechanical tests were performed on a powder-metallurgically processed 7093/SiC/15p discontinuously reinforced aluminum (DRA) composite in different heat-treatment conditions, to determine the influence of matrix characteristics on the composite response. The work-hardening exponent and the strain to failure varied inversely to the strength, similar to monolithic Al alloys, and this dependence was independent of the dominant damage mode. The damage consisted of SiC particle cracks, interface and near-interface debonds, and matrix rupture inside intense slip bands. Fracture surfaces revealed particle fracture-dominated damage for most of the heat-treatment conditions, including an overaged (OA) condition that exhibited a combination of precipitates at the interface and a precipitate-free zone (PFZ) in the immediate vicinity. In the highly OA conditions and in a 450°C as-rolled condition, when the composite strength became less than 400 MPa, near-interface matrix rupture became dominant. A combination of a relatively weak matrix and a weak zone around the particle likely contributed to this damage mode over that of particle fracture. Fracture-toughness tests show that it is important to maintain a proper geometry and testing procedure to obtain valid fracture-toughness data. Overaged microstructures did reveal a recovery of fracture toughness as compared to the peak-aged (PA) condition, unlike the lack of toughness recovery reported earlier for a similar 7XXX(Al-Zn-Cu-Mg)—based DRA. The PA material exhibited extensive localization of damage and plasticity. The low toughness of the DRA in this PA condition is explored in detail, using fractography and metallography. The damage and fracture micromechanisms formed the basis for modeling the strength, elongation, toughness, and damage, which are described in Part II of this work.

Abstract: Phase transformations and the resulting microstructural evolution of near-Ti2AlNb and Ti-12Al-38Nb O+bcc orthorhombic alloys were investigated. For the near-Ti2AlNb alloys, the processing temperatures were below the bcc transus, while, for Ti-12Al-38Nb, the processing temperature was supertransus. Phase evolution studies showed that these alloys contain several constituent phases, namely, bcc, O, and α 2; when present, the latter was in small quantities compared to the other phases. The transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray investigations of samples that were solutionized and water quenched were used to estimate the phase fields, and a pseudobinary diagram based on Ti=50 at. pct was modified. The aging-transformation behavior was studied in detail. For solutionizing temperatures between 875 C and the bcc transus, the phase composition and volume fraction of the near-Ti2AlNb alloys adjusted through relative size changes of the equiaxed B2, O, and α 2 grains. The aging behavior followed three distinct transformation modes, dependent on the solutionizing and aging temperatures. Widmanstatten formation was observed when a new phase evolved from a parent phase. Thus, Widmanstatten O phase precipitated within the B2 phase for supertransus fully B2 microstructures, as well as for substransus α 2+B2 microstructures. Similarly, Widmanstatten B2 phase can form from a fully O microstructure, a transformation that has not been observed before. In the case of equiaxed O+B2 solutionized and water-quenched microstructures, Widmanstatten O-phase formation occurred only below 875 C. For the subtransus-solutionized and water-quenched microstructures, a second aging transformation mode, cellular precipitation, was dominant below 750 C. This involved formation of coarse and lenticular O phase that grew into the prior B2 grains from the grain boundaries. A third transformation mode involved composition-invariant transformation, where the fully B2 supertransus-solutionized and water-quenched microstructure transformed to a fully O microstructure at 650 C. This microstructure reprecipitated B2 phase out of the O phase with continued aging time. For Ti-12Al-38Nb, Widmanstatten O precipitation remained the only transformation mode. It is shown that subtransus processing offers flexibility in controlling microstructures through postprocessing heat treatments.

Estimates for the thickness of the interface between poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) and copolymers of styrene–acrylonitrile (SAN) and styrene–maleic anhydride (SMA) based on the theory of Helfand and Tagami are compared to neutron reflectivity (NR) measurements. Good agreement is found between the NR measurements and theoretical predictions that make use of a mean field binary interaction model and previously reported binary interaction energies. The techniques outlined in this work may be used to understand relationships between the mechanical properties of multiphase polymer blends and the fundamental thermodynamics of polymer interactions. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 3115–3125, 1998

Abstract: The transverse creep response of an 8-ply SiC (SCS-6)/Ti-6Al-4V composite was measured at 482 °C from 69 to 276 MPa. Creep samples with fibers exposed at the edges as well as specimens with fully embedded fibers were tested under stepped loading conditions with increasing load. The response of each sample geometry was compared with creep data from the unreinforced matrix (‘neat’ material). The samples with exposed fiber ends exhibited minimum creep rates that were higher than those of the neat material at all stresses, and the stress exponent was slightly large than the neat material. The embedded fiber samples possessed minimum creep rates that were smaller than the neat material at low stresses (<115 MPa), but became equivalent to the exposed fiber data at the highest stress (276 MPa). The apparent stress exponent for the embedded fiber composite was significantly larger than the neat material. The exposed fiber test data were well represented by a standard Crossman analysis, where the fibers were considered to have completely debonded. A stress singularity in the interfacial region at the sample edge is responsible for this behavior. The Crossman model was modified to incorporate the effect of a finite interface strength (120 MPa), and this was used to describe the response of the samples with embedded fibers. A reasonable fit to this representation was obtained. However, the measured minimum creep rate at the lowest stress was significantly lower than that predicted by the Crossman analysis for fully bonded fibers.

Abstract: The role of elastic shielding in reducing the local stress intensity factor (SIF) range during fatigue crack growth (FCG) has been investigated using several single-ply composites with significantly different interfacial characteristics. The specimen geometry necessitated the fatigue crack to initially grow through a monolithic matrix region before impinging on a set of longitudinally oriented fibers. This facilitated the assessment of the crack shielding phenomenon from two regions: the region where the crack interacted with the first fiber, and at high stress levels when nonbridging conditions prevailed in the fibrous region. The extent of shielding was nearly identical in the two measurements for a given composite system. However, the shielding contribution was found to depend on the interface bond strength; the interface with the highest bond strength provided the largest degree of crack retardation in both cases. A preliminary assessment of this dependency has been provided. The implications of using the correct shielding factor on both fiber strength and life prediction are also discussed.