Journal Articles

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Author: search.filters.author.Chandran, Vidya

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    Mechanical and tribological performance of Al-Fe-SiC-Zr hybrid composites produced through powder metallurgy process
    (IOP Publishing Ltd, 2021-01-22) Raghav G R; Janardhanan, Sheeja; Chandran, Vidya; V Sruthi
    In this work a ternary Al-Fe-SiC metal matrix composites were reinforced using Zr particles through powder metallurgy process. The Al matrix and the reinforcements were mixed in high energy ball mill at a speed of 250 rpm over a period of 5 h so as to develop a homogenously dispersed composite material. The composite powders are then pressed at 500 MPa using hydraulic press. The compressed composite green compacts are then sintered at 500 °C for 2 h and allowed to cool under furnace atmosphere. The densities, micro hardness and compressive strength of Al-Fe-SiC-Zr composites were investigated and reported. The composite materials were characterized using SEM, EDS and XRD. The density of Al-10Fe-10SiC-10Zr hybrid composites was found to be around 3.44 g cm−3. The Zr particles have influenced the micro hardness of the composite materials. The micro hardness of the Al-10Fe-10SiC-10Zr hybrid composites was found to be better compared to Al-10Fe and Al-10Fe-10SiC hybrid composites. The compressive strength of the Al-10Fe-10SiC-10Zr hybrid composites was around 205 MPa which is 44% higher than the Al-10Fe composite material. The porosity of the hybrid composites has reduced when compared to that of Al-10Fe and Al-10Fe-10SiC hybrid composites. The wear studies reveal that Al-10Fe-10SiC-10Zr bear out better wear resistance. The predominant wear mechanism was identified as adhesive wear followed by plastic deformation. This improved wear resistance was due to the formation of oxides layers such Al2O3, Fe2O3 and also due to the presence of AlFe3 and Al3Zr4 intermetallics.
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    On the design of a compact emergency mechanical ventilator with negative expiratory exit pressure for COVID-19 patients
    (Taylor & Francis, 2023-02-17) Janardhanan, Sheeja; Chandran, Vidya; Rajan, Rajesh
    The present work deals with the design of a cylinder-piston arrangement to deliver the required tidal volume (TV) of air to the patient through the respiratory tract especially in the setting of severe acute respiratory syndrome corona virus 2 (SARS CoV-2) or corona virus disease (COVID-19). The design ensures that only the desired volume of air is delivered in each breath and a negative pressure is retained at the delivery point in a separate cylinder. The frequency of piston motion is the same as that of the average human respiratory rate (RR). The effect of negative pressure on time of evacuation under the present condition has been verified. The present design provides a compact ventilator unit with a surface area of 0.8 × 0.4 m2 with a minimal power requirement of 116.48 W. An RR of 16 is obtained with a volume flow rate in lit/s by using a twin cylinder arrangement with bore diameter 0.1 m and length 0.4 m. The ratio of inspiration time to expiration time is designed to be 1:2 by controlling the stroke frequency as 16 and piston speed 0.32 m/s. The present design provides promising quantitative information on the design of an automated continuous mechanical ventilator (CMV), which is different from bag mask valve (BMV) operated ventilators, and on preventing and minimising barotrauma.