Effects of Process Parameters on the Mechanical Properties of Glass Fabric Reinforced Polypropylene Composites

S. Suresh,V. S. Senthil Kumar 한국고분자학회 2018 폴리머 Vol.42 No.4

The present study investigates the effects of process parameters such as fabric structure, fabric orientation and compatibilizer concentration on the mechanical properties of fabric reinforced polypropylene composites. Two types of glass fabric reinforced composites with two different stacking sequences were prepared by compressing molding. The composites were prepared with and without compatibilizer for the purpose of analyzing interfacial-bonding. The composites were investigated in terms of tensile, flexural and impact strength for evaluation of the effects of the process parameters. The factorial approach is used to design the experimental layout. The test results revealed that Type-2 fabric reinforced composite in [0-90]4 orientation with 8 wt% compatibilizer possesses better mechanical properties. Tensile, flexural and impact strength were increased by 106%, 235% and 100%, respectively. Analysis of variance was used to identify the most significant factors which would affect the performance of composites. Morphological study explored the presence of strong interfacial-bonding between the materials.

Effect of Pulsed Current GTA Welding Parameters on the Fusion Zone Microstructure of AA 6061 Aluminium Alloy

( T. Senthil Kumar ),( V. Balasubramanian ),( S. Babu ),( M. Y. Sanavullah ) 대한금속재료학회 ( 구 대한금속학회 ) 2007 METALS AND MATERIALS International Vol.13 No.4

AA6061 aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of food processing equipment, chemical containers, passenger cars, road tankers, and railway transport systems. The preferred process for welding these aluminium alloys is frequently Gas Tungsten Arc (GTA) welding due to its comparatively easy applicability and lower cost. In the case of single pass GTA welding of thinner sections of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current processes. The use of pulsed current parameters has been found to improve the mechanical properties of the welds compared to those of continuous current welds of this alloy due to grain refinement occurring in the fusion zone. In this investigation, an attempt has been made to develop a mathematical model to predict the fusion zone grain diameter incorporating pulsed current welding parameters. Statistical tools such as design of experiments, analysis of variance, and regression analysis are used to develop the mathematical model. The developed model can be effectively used to predict the fusion grain diameter at a 95 % confidence level for the given pulsed current parameters. The effect of pulsed current GTA welding parameters on the fusion zone grain diameter of AA 6061 aluminium alloy welds is reported in this paper.

Improved Thermal Stability of Green InGaN/GaN Multiple-Quantum-Well Light-Emitting Diodes with an AlGaN/GaN Short-Superlattice-Inserted Structure

Y. S. Lee,M. Senthil Kumar,T. V. Cuong,J. Y. Park,J. H. Ryu,S. J. Chung,E.-K. Suh,C.-H. Hong 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.1

We report an amelioration of the electrical, thermal and optical performances of green InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with AlGaN/GaN short- superlattice (SSL)-inserted structure grown using metal-organic chemical vapor deposition. Ac- cording to an atomic force microscopic study, the GaN template with the SSL-inserted structure shows a signicant reduction in pit density compared to the conventionally-grown template. The insertion of the SSL is also found to alleviate the eect of threading dislocations on the degradation of the electrical performance and promotes the stability of the K-factor and a low thermal resis- tance under a long-term acceleration test. A relatively higher optical output power is obtained for SSL-inserted InGaN/GaN green LEDs at high injection currents. We report an amelioration of the electrical, thermal and optical performances of green InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with AlGaN/GaN short- superlattice (SSL)-inserted structure grown using metal-organic chemical vapor deposition. Ac- cording to an atomic force microscopic study, the GaN template with the SSL-inserted structure shows a signicant reduction in pit density compared to the conventionally-grown template. The insertion of the SSL is also found to alleviate the eect of threading dislocations on the degradation of the electrical performance and promotes the stability of the K-factor and a low thermal resis- tance under a long-term acceleration test. A relatively higher optical output power is obtained for SSL-inserted InGaN/GaN green LEDs at high injection currents.

Experimental investigation of weld characteristics on submerged friction stir welded 6061-T6 aluminum alloy

C. Rathinasuriyan,V. S. Senthil Kumar 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8

Mechanical properties such as fatigue life, corrosion resistance, brittle fracture, hardness and dimensional stability mainly depend on the residual stresses of the welded sample. The main purpose of the research work is measuring the residual stress at different rotational speeds and water heads and correlates the results with its microhardness and its grain size. In the present study, submerged friction welding was conducted at different rotational speeds of 800, 1000 and 1200 rpm and water heads of 10 and 20 mm, respectively, while the welding speed and axial load were maintained constant. Residual stress was evaluated at the center of the nugget zone on the welded samples using the nondestructive of X-ray diffraction method. Normal friction stir welding (without water head) experiments were carried out later at various rotational speeds of 800, 1000 and 1200 rpm for comparing with the results of the SFS welded samples. The results indicate that the value of d-spacing, lattice parameter and residual stress of submerged friction stir welded sample as higher than that of the normal FS welded sample. The grain size of the SFS welded samples is compared with those of FS welded samples using a scanning electron microscopy. SFSW samples exhibit smaller grain sizes compared to the normal FSW.

Current Status and Development of Submerged Friction Stir Welding: A Review

Rathinasuriyan Chandran,E. Pavithra,R. Sankar,V. S. Senthil Kumar 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.2

Submerged Friction Stir Welding is a modification of the friction stir welding process in which the water as the coolant is employed to standardize the temperature. It is considered as a green and environmentally friendly welding technology because of low energy consumption, no gas emission, and no need for consumable material. It is applied to structural purposes like oil platforms and pipelines, or in industrial and laboratories for enhancing the weld strength. This review paper is classified into three categories, the first one studies the preceding experimental investigations, the second one is modelling/optimization, and the third one is current status and development of submerged friction stir welding. The experimental results of the previous research findings in submerged friction stir welded sample with performance characteristics, tensile properties, microhardness, fracture analysis and corrosion resistance, macro/microstructure analysis on the various materials are discussed. This review articles concludes with recommendations for future research exertion

Cardioprotective Effect of Squalene on Lipid Profile in Isoprenaline-Induced Myocardial Infarction in Rats

R. Anandan,K.H. Sabeena Farvin,S. Hari Senthil Kumar,K.S. Shiny,Suseela Mathew,T.V. Sankar,P.G. Viswanathan Nair 한국식품영양과학회 2006 Journal of medicinal food Vol.9 No.4

We studied the cardioprotective effect of squalene on isoprenaline-induced myocardial infarction in male al-bino rats with respect to changes in the levels of lipid components in plasma and heart tissue. Prior administration of 2% squa-lene in feed for 45 days significantly reduced the isoprenaline-induced elevation in the levels of cholesterol, triglycerides, andfree fatty acids in plasma and heart tissue of rats following myocardial infarction. It exerted an anitlipidemic effect by re-ducing the level of low-density lipoprotein cholesterol with a parallel rise in the level of high-density lipoprotein cholesterolin plasma of experimental rats. A tendency to prevent the isoprenaline-induced depletion of phospholipids in the myocardiumof experimental rats was also observed. In the present study, the pretreatment with squalene significantly counteracted the iso-prenaline-induced lipid peroxidation and maintained the rats at near normal status. The results of the present study indicatethat the overall cardioprotective effect of squalene is probably related to an inhibition of lipid accumulation by its hypolipi-demic properties and/or its antioxidant properties.