Experimental Investigation on Effects of Wire Electro Discharge Machining of Ti<Subscript>50</Subscript>Ni<Subscript>45</Subscript>Co<Subscript>5</Subscript> Shape Memory Alloys

TiNiCo shape memory alloy is most popular shape memory alloy for biomedical applications due to their outstanding properties such as shape memory effect, pseudoelasticity and transformation temperature. Machining of such kind of alloys is very difficult through conventional machining process is very difficult because they may affect their internal properties of these alloys. However conventional machining processes give poor surface quality during the machining hence non-conventional machining processes such as (wire electro discharge machining, water jet machining and electro discharge machining etc.) are more suitable for machining of such kind of alloy. From the literature it has been found that Wire electro discharge machining (WEDM) is more suitable non-conventional machining process for such kind of alloy. Present study exhibits the effects WEDM characteristics of Ti₅₀Ni₄₅Co₅ shape memory alloy. L-9 orthogonal array has been created by using Taguchi as a design method for machining of selected alloy and machined surface characterization has been carried out at the optimized process parameters with respect to microstructures, surface topography, microhardness, XRD analysis and residual stresses. To find the optimum setting of the input process parameters a couple of optimization techniques are used, namely principal component analysis (PCA) and Gray relational analysis (GRA) technique. 125μs pulse on time (T_on), 35μs pulse off time (T_off) and 40V servo voltage (SV) were found as an optimal setting for the higher material removal rate (MRR) with better surface roughness (SR) in the present study. Moreover, characterization of the machined surface is performed with respect to microstructures, surface topography, microhardness analysis, XRD and residual stresses. Harder surface observed near the cutting edge and TiNio₃ Tio₂ and CuZn were noticed on the surface of machined component through XRD analysis. However, compressive residual stress has been noticed on the machined surface during WEDM process.     

Effects of Wire Electro-Discharge Machining Process Parameters on the Machined Surface of Ti50Ni49Co1 Shape Memory Alloy

Silicon - Wire electro-discharge machining is one of the advanced machining processes which can machine all conductive materials without changing their internal properties. Pulse on time and servo...     

Removal of copper and cadmium from the aqueous solutions by activated carbon derived from Ceiba pentandra hulls

Activated carbon prepared from Ceiba pentandra hulls, an agricultural solid waste by-product, for the removal of copper and cadmium from aqueous solutions has been studied. Parameters such as equilibrium time, effect of pH and adsorbent dose on removal were studied. The adsorbent exhibited good sorption potential for copper and cadmium at pH 6.0. C=O and S=O functional groups present on the carbon surface were the adsorption sites to remove metal ions from solution. The experimental data was analysed by both Freundlich and Langmuir isotherm models. The maximum adsorption capacity of copper and cadmium was calculated from Langmuir isotherm and found to be 20.8 and 19.5 mg/g, respectively. The sorption kinetics of the copper and cadmium have been analysed by Lagergren pseudo-first-order and pseudo-second-order kinetic models. The desorption studies were carried out using dilute hydrochloric acid solution and the effect of HCl concentration on desorption was also studied. Maximum desorption of 90% for copper and 88% for cadmium occurred with 0.2 M HCl.     

Effect of water injection and spark timing on the nitric oxide emission and combustion parameters of a hydrogen fuelled spark ignition engine

One of the main problems with hydrogen fuelled internal combustion engines is the high NO level due to rapid combustion. Use of diluents with the charge and retardation of the spark ignition timing can reduce NO levels in Hydrogen fuelled engines. In this work a single cylinder hydrogen fuelled engine was run at different equivalence ratios at full throttle. NO levels were found to rise after an equivalence ratio of 0.55, maximum value was about 7500 ppm. High reductions in NO emission were not possible without a significant drop in thermal efficiency with retarded spark ignition timings. Drastic drop in NO levels to even as low as 2490 ppm were seen with water injection. In spite of the reduction in heat release rate (HRR) no loss in brake thermal efficiency (BTE) was observed. There was no significant influence on combustion stability or HC levels.     

Effects of material properties on the fragmentation of brittle materials

We present a fundamental investigation of the influence of material and structural parameters on the mechanics of fragmentation of brittle materials. First, we conduct a theoretical analysis (similar to Drugan’s single wave problem, Drugan, W.J. (2001), Journal of Mechanical and Physics Solids 49, 1181–1208.) and obtain closed form solutions for a problem coupling stress wave propagation and single cohesive crack growth. Expressions for a characteristic fragment size s ₀ and a characteristic strain-rate are given. Next, we use a numerical approach to analyze a realistic fragmentation process that involves multiple crack interactions. The average fragment size s is calculated for a wide variety of strain-rates and a broad range of material parameters. Finally, we derive an empirical function that relates the normalized fragment size s/s ₀ to the normalized strain-rate and that fits all of the numerical results with a single master curve.     

Evaluation of mechanical properties of Al2O3 and TiO2 nano filled enhanced glass fiber reinforced polymer composites

The present investigation has emphasized the implication of nano fillers (Al₂O₃ and TiO₂) combined additions in glass fiber reinforced polymer composite on the variation of interlaminar shear strength (ILSS). The experiment has also investigated the effect of crosshead speed during testing and subsequent fracture surface analysis to find out the possible failure modes by scanning electron micrograph examinations. Loss and storage modulus have been experimentally evaluated to support the new findings in the present experimental design. It has been observed that the concurrent presence of nano Al₂O₃ and TiO₂ fillers improves the ILSS. Dynamic mechanical thermal analysis indicated that, the addition of nano fillers reduces the storage and loss modulus of the composites. However, glass transition temperature has not been altered by the nano fillers addition. Box–Behnken design of experiment of surface response methodology has been adopted to optimize the filler content and crosshead speed. A second order mathematical model has been developed and the predicted optimum input parameters are 0.3 wt % Al₂O₃, 0.15 wt %TiO₂, and 500 mm/min crosshead speed. Furthermore, the model predicted results are compared with experimental one and found a close agreement between them. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44274.