•S – N curves for samples machined at different conditions are presented.•Fatigue performance is very similar for all samples at higher cyclic loading.•Contributions of machining conditions were ...noted at lower cyclic loading.•Fatigue cracks initiated from the both sides of the samples.•Surface roughness and feed did not contribute to fatigue performance.•Recast layer and heat affected zone are the main contributor to the fatigue performance.
The effect of pulse on time, pulse off time and wire tension were investigated on the fatigue life, crack propagation, surface roughness and machining feed during wire EDM of Ti-6Al-4V alloy. The fatigue performance of all samples is very similar at higher cyclic loading. The machining conditions affected the lower cyclic loading. Lower pulse-on time and higher pulse-off time gave the longest life at lower cyclic loading. The higher wire tension gave shorter life and then remained almost constant at lower tension. It seems that the recast layer and heat affected zone are the main contributor to the fatigue performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
ABSTRACT AstroSat is a multi-wavelength satellite launched on 2015 September 28. The CZT Imager of AstroSat on its very first day of operation detected a long duration gamma-ray burst (GRB), namely ...GRB 151006A. Using the off-axis imaging and spectral response of the instrument, we demonstrate that the CZT Imager can localize this GRB correctly to about a few degrees, and it can provide, in conjunction with Swift, spectral parameters similar to those obtained from Fermi/GBM. Hence, the CZT Imager would be a useful addition to the currently operating GRB instruments (Swift and Fermi). Specifically, we argue that the CZT Imager will be most useful for the short hard GRBs by providing localization for those detected by Fermi and spectral information for those detected only by Swift. We also provide preliminary results on a new exciting capability of this instrument: the CZT Imager is able to identify Compton scattered events thereby providing polarization information for bright GRBs. GRB 151006A, in spite of being relatively faint, shows hints of a polarization signal at 100-300 keV (though at a low significance level). We point out that the CZT Imager should provide significant time resolved polarization measurements for GRBs that have fluence three times higher than that of GRB 151006A. We estimate that the number of such bright GRBs detectable by the CZT Imager is five to six per year. The CZT Imager can also act as a good hard X-ray monitoring device for possible electromagnetic counterparts of gravitational wave events.
This paper investigates comprehensive knowledge regarding joining CFRP and aluminium alloys in available literature in terms of available methods, bonding processing and mechanism and properties. The ...methods employed comprise the use of adhesive, self-piercing rivet, bolt, clinching and welding to join only CFRP and aluminium alloys. The non-thermal joining methods received great attention though the welding process has high potential in joining these materials. Except adhesive bonding and welding, other joining methods require the penetration of metallic pins through joining parts and therefore, surface preparation is unimportant. No model is found to predict the properties of jointed structures, which makes it difficult to select one over another in applications. The choice of bonding methods depends primarily on the specific applications. The load-bearing mechanism of bolted joints is predominantly the friction that is the first stage resistance. Hybrid joints performance is enhanced by combining rivets, clinch or bolts with adhesives.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Errors generated in wire EDM of 2205 duplex stainless steel.•Total contributions of interactions are reasonably high for all cases.•Wire tension has highest contribution on cylindricity error.•Pulse ...off time and wire tension have highest contribution on circularity error.•Pulse off time has maximum contributions on diameter error.
The present paper studies different types of errors generated on the feature (cylindrical holes) which was fabricated by the wire EDM of 2205 duplex stainless steel. Different experimental parameters such as, pulse on time, pulse off time and wire tension on the feature as well as the contribution of these parameters on cylindricity error, circularity error and diameter error were explored. Moreover, interactions among the input parameters were also considered. It was found that the total contributions of interactions between different parameters are reasonably high for all the cases which make the modelling process very complex for cylindricity, circularity and diameter errors in term of the range of parameter considered in this investigation. Wire tension has highest contribution on cylindricity error which is lowest at high value wire tension. Pulse on time has minor contribution on the cylindricity error and it increases with the increase of pulse on time. Pulse of time does not have any influence on the cylindricity error. The circularity error was lowest at medium pulse off time and medium wire tension; and those two parameters have almost similar and highest contributions. The pulse on time has around 14% contribution on circularity error and the medium value of it minimizes the circularity error. The input parameters such has pulse on time, pulse off time and wire tension have around 13%, 16% and 7% contributions respectively on diameter error which is minimized at medium pulse on time, and low pulse off time and low wire tension.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Wear of elastomers is different and far more complex than that of metallic materials, which arises owing to the effect of various operating parameters as well as physical and mechanical properties of ...the elastomers. Therefore, the prediction of wear of the elastomers while sliding against rough counterparts is of practical importance. The current study attempts to formulate equations to predict the wear rate of elastomers by identifying and considering the dominant material properties (such as, hardness, tensile strength, and elongation at break) as well as operating variables that control the wear The exponents and coefficient are obtained experimentally, which represent the significance of each parameter. A good correlation is observed between the calculated and measured wear rates.
•Wear equations are developed by considering the dominant mechanical properties of the material and operating variables.•The constants of the equations are obtained experimentally, which represent the significance of each parameter.•A good correlation is observed between the calculated and measured wear rates.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK, ZAGLJ
Titanium alloys are difficult to machine using conventional methods, therefore, nonconventional processes are often chosen in many applications. Electrical discharge machining (EDM) is one of those ...nonconventional processes that is used frequently for shaping titanium alloys with their respective pros and cons. However, a good understanding of this process is very difficult to achieve as research results are not properly connected and presented. Therefore, this study investigates different types of EDM processes such as, wire EDM, die-sink EDM, EDM drill and hybrid EDM used to machine titanium alloys. Machining mechanism, tool electrode, dielectric, materials removal rate (MRR), and surface integrity of all these processes are critically analysed and correlated based on the evidence accessible in literature. Machining process suffer from lower material removal rate and high tool wear while applied on titanium alloys. Formation of recast layer, heat affected zone and tool wear is common in all types of EDM processes. Additional challenge in wire EDM of titanium alloys is wire breakage under severe machining conditions. The formation of TiC and TiO2 are noticed in recast layer depending on the type of dielectrics. Removal of debris from small holes during EDM drilling is a challenge. All these restricts the applications EDMed titanium alloys in high-tech applications such as, aerospace and biomedical areas. Most of these challenges come up due to extraordinary properties such as, low thermal conductivity, high melting point and high hardness, of titanium alloys. Though hybrid EDM has been introduced and there is some work on simulation of EDM process, further developments in EDM of this alloy is required for widening the application of this methods.
Materials Science; Mechanical Engineering; Metallurgical Engineering; Manufacturing Engineering; Metals; Machining; Structural Behavior; Titanium alloy; Electrical discharge machining; surface integrity; material removal rate.
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This study aims to investigate the fundamental deformation mechanism of Ti-based bulk metallic glass under mechanical loading by a cutting tip. The cutting tip interaction is resolved into two ...separate actions, namely nanoindentation by using a Berkovich diamond indenter and contact sliding under a pin-on-disk configuration. The deformation details in the specimens due to the action of the corresponding mechanical loading were analyzed by SEM and TEM. It was found that under nanoindentation, the plastic deformation is evidenced by a series of pop-ins in load–displacement graphs. The temperature rise at the contact interface during sliding must have been above the glass transition temperature and the onset temperature of crystallization, leading to the formation of discrete nanocrystalline particles in the immediate subsurface and hence bringing about an increase in hardness of the metallic glass in the wear tracks.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abrasive wear behaviour of WC-Co and Fe/Cu-based nanostructured coatings has been investigated under dry and slurry conditions in this study. The retention of nanostructured coating constituents was ...confirmed together with the formation of various metallic and ceramic phases. Abrasive wear rate of nanostructured WC-Co coating was one order lower than that of micro-structured coatings in both conditions. Relatively higher abrasion wear resistance of such coatings compare to reference metallic material was because of comparatively smaller debris formation. These debris roll in between the moving surfaces and thus limit the wear of coating materials. Another aspect of higher abrasive wear resistance is homogeneous distribution of hard (WC and Al2O3) particles within relatively soft matrix (Co and FeCu) as revealed by SEM investigation.
•Nanostructured coatings were successfully deposited from engineered nanosized powders using high thermal spraying.•Abrasive wear rate of nanostructured WC-based coating is one order of magnitude lower than that of micro-structured coating.•Different coating groups (WC-based or Fe/Cu-based) show different degradation mechanism during abrasion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Osseointegration of an implant takes place when cells interact with implanted material, which depends on the surface and microstructural properties of the materials. In order to study the response of ...surface modified bioactive glasses in body fluid, glass samples with nominal composition (wt.%) 45SiO2–24.5CaO–24.5Na2O–6P2O5 are prepared by melt-quench technique and characterized for thermo-physical and structural properties. The glass samples are irradiated with nanosecond laser at different laser fluences. Structural and microstructural features of laser treated samples are investigated by Raman and scanning electron microscope. The morphology of laser treated glass samples has shown the formation of porous microstructure with pore size varying from 50nm to 2μm. In vitro testing of laser treated samples in simulated body fluid reveals a significant improvement in the formation of bioactive layer in comparison to untreated bioactive glass samples.
•Surface morphology of glass samples is influenced by incident laser fluence.•The porous microstructures are obtained in laser treated samples.•Microstructure changes with an increase in laser fluence.•Laser treated samples show an improvement in the formation of bioactive layer.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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