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R. Rajasekaran,A. K. Lakshminarayanan,M. Vasudevan,P. Vasantha Raja 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11
The 316LN Stainless Steel (SS) weld joints were fabricated using Tungsten Inert Gas (TIG) Welding and Activated FluxTungsten Inert Gas (A-TIG) Welding techniques with suitable process parameters. Initially, basic mechanical properties wereevaluated across weld joints. Further microstructural study of the base metal, TIG, and A-TIG joints were accomplishedusing Optical Microscopy (OM), Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM)techniques. The microstructural characterization revealed higher grain size variations at the fusion zone of the A-TIG jointdue to the slow cooling rate and reversed Marangoni convection effect. The Stress Corrosion Cracking (SCC) susceptibilityof the TIG and A-TIG welded joints was assessed using five different loading/Stress conditions. The constant load boiling45 wt% Magnesium Chloride Hexahydrate (MgCl2.6H2O) solution as per ASTM G36-94 standard was used to evaluate theSCC susceptibility of the welded joints. The SCC (crack initiation and propagation) of the base metal and welded jointsoccurred by the anodic dissolution and Hydrogen Induced Cracking mechanisms. For the welded joints additionally, thedissolution of the δ-ferrite increased the crack growth rate. The A-TIG joint exhibited lesser SCC resistance than the TIGjoint for the following major reasons: (i) Formation of the large dendrites (ii) Presence of the higher grain size variations atthe fusion zone. Moreover, both welded joints showed lesser SCC resistance than the base metal due to the dissolution ofthe δ-ferrite and the residual stress formation. The fractographic studies for the base metal, TIG, and A-TIG joints revealedthe brittle nature of transgranular SCC failure.
Vasudevan A.,Selvaraj N.,Ganapathi A.,Anbazhagan V. Ramesh,Choi, C.W. The Korean Society of Plant Biotechnology 2006 식물생명공학회지 Vol.33 No.4
Effects of ethylene inhibitors like silver nitrate $(AgNO_3)$, cobalt chloride $(CoCl_2)$ and Salicylic acid (SA) on multiple shoot induction and their impact on ethylene production using embryonal cotyledon cultures of Cucumis sativus L. were examined. The optimum concentration of $AgNO_3\;(40{\mu}M),\;CoCl_2\;(20{\mu}M)\;and\;SA\;(20{\mu}M)$, separately, induced maximum number of shoots on Murashige and Skoog's (MS) medium supplemented optimally with $4.44{\mu}M$ BA and $0.25{\mu}M$ NAA. Among the three ethylene inhibitors tested, $AgNO_3$ produced maximum number of shoots when compared to $CoCl_2$ and SA Ethylene production was monitored in all the treatments with $AgNO_3/CoCl_2/SA$ and it was observed that the treatment with $AgNO_3$ alone showed increase in ethylene production when compared to $CoCl_2$ and SA Even though ethylene concentration was the highest in $AgNO_3$ treated explants, maximum number of shoots was obtained.
Optimal layout of a partially treated laminated composite magnetorheological fluid sandwich plate
R. Vasudevan,R. Manoharan,A.K. Jeevanantham 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.16 No.6
In this study, the optimal location of the MR fluid segments in a partially treated laminated composite sandwich plate has been identified to maximize the natural frequencies and the loss factors. The finite element formulation is used to derive the governing differential equations of motion for a partially treated laminated composite sandwich plate embedded with MR fluid and rubber material as the core layer and laminated composite plate as the face layers. An optimization problem is formulated and solved by combining finite element analysis (FEA) and genetic algorithm (GA) to obtain the optimal locations to yield maximum natural frequency and loss factor corresponding to first five modes of flexural vibration of the sandwich plate with various combinations of weighting factors under various boundary conditions. The proposed methodology is validated by comparing the natural frequencies evaluated at optimal locations of MR fluid pockets identified through GA coupled with FEA and the experimental measurements. The converged results suggest that the optimal location of MR fluid pockets is strongly influenced not only by the boundary conditions and modes of vibrations but also by the objectives of maximization of natural frequency and loss factors either individually or combined. The optimal layout could be useful to apply the MR fluid pockets at critical components of large structure to realize more efficient and compact vibration control mechanism with variable damping.
Comparison of mechanisms of advanced mechanical surface treatments in nickel-based superalloy
Gill, A.,Telang, A.,Mannava, S.R.,Qian, D.,Pyoun, Y.S.,Soyama, H.,Vasudevan, V.K. Elsevier Sequoia 2013 Materials science & engineering. properties, micro Vol.576 No.-
Mechanical surface enhancement techniques are used to introduce compressive residual stresses to enhance the fatigue life and corrosion resistance of metallic components. In this study, we compare the effects of three advanced mechanical surface enhancements treatments: laser shock peening, cavitation shotless peening and ultrasonic nano structure modification on residual stress, hardness, plastic deformation and changes in near surface microstructure introduced in a Ni-Base superalloy, IN718 SPF(Super plastic forming). Coupons of the alloy were peened using two different conditions of each treatment and results compared to achieve a better understanding of underlying mechanisms of these techniques. Results indicate that there are significant differences in mechanisms of these surface treatments leading to differences in material response.
Surface grain boundary engineering of Alloy 600 for improved resistance to stress corrosion cracking
Telang, A.,Gill, A.S.,Tammana, D.,Wen, X.,Kumar, M.,Teysseyre, S.,Mannava, S.R.,Qian, D.,Vasudevan, V.K. Elsevier Sequoia 2015 Materials science & engineering. properties, micro Vol.648 No.-
In this paper, we demonstrate a novel method for grain boundary engineering in Alloy 600 using iterative cycles of ultrasonic nanocrystal surface modification (UNSM) and strain annealing to modify the near surface microstructure (~250@?m) for improved stress corrosion cracking (SCC) resistance. These iterative cycles resulted in increased fraction of special grain boundaries whilst decreasing the connectivity of random grain boundaries in the altered near surface region. A disrupted random grain boundary network and a large fraction of low CSL boundaries (Σ3-Σ27) reduced the propensity to sensitization. Slow strain rate tests in tetrathionate solutions at room temperature show that surface GBE lowered susceptibility to intergranular SCC. Detailed analysis of cracks using Electron Back-scattered Diffraction showed cracks arrested at J1(1-CSL) and J2 (2-CSL) type of triple junctions. The probability for crack arrest, calculated using percolative models, was increased after surface GBE and explains the increase in resistance to SCC.
Factors Influencing Association of Intermediaries in the Supply Chain of Consumer Healthcare Brands
SURESH, A.S.,VASUDEVAN, M.,VINOD, Sharma Korea Distribution Science Association 2021 유통과학연구 Vol.19 No.1
Purpose: The rural market in India provides tremendous scope for FMCG consumer healthcare companies to market their products because of a significant increase of rural purchasing power. Many empirical studies in this area highlight the challenges and opportunities for marketers in the FMCG space. Research articles are not in abundance to understand intermediaries' expectations in the supply chain specific to consumer healthcare products. The existing literature did not significantly address the challenges of channel partners in the rural market. The present study aims to determine the retailer expectations from manufacturers and channel members' mutual expectations in the FMCG distribution channel. Research design and Methodology: The present study adopted a qualitative research methodology. Fifty respondents from each level of distribution channel such as super-stockist, distributors and retailers in central India were identified and an interview method was adopted to collect the data. Results: Nineteen factors were identified to influence the intermediaries for involvement in the business with any FMCG brand. Factors like Profit margin, reverse logistics, credit terms, return on investment, timely payments were crucial for managing the expectations of all intermediaries. This study provides academic as well as practical implications in terms of enabling the industry to align its channel management strategies accordingly.
Santhosh, P.,Gopalan, A.,Vasudevan, T.,Lee, Kwang-Pill Wiley Subscription Services, Inc., A Wiley Company 2006 Journal of applied polymer science Vol.101 No.1
<P>Composites of thermoplastic polyurethane (TPU) with poly(diphenylamine) (PDPA) were prepared by entrapping diphenylamine (DPA) molecules into the matrix of TPU and polymerizing DPA within the TPU matrix. Swelling rate of the parent TPU and the composites in 1M LiClO<SUB>4</SUB> in propylene carbonate solution were compared to understand the influence of the presence of PDPA in the composite in altering the morphology, conductivity, and electrolyte behavior. The nitrogen atoms in the PDPA interact and are likely to form hydrogen bonding with the carbonyl and ether groups in TPU. As a result, different morphology, thermal, and impedance behavior were witnessed for the composites in comparison to TPU. Results from differential scanning calorimetry, scanning electron microscopy (SEM), thermogravimetric analysis, and ac impedance measurements were obtained as supporting evidences. An increase in glass transition temperature for the composite in comparison to TPU infers the increase in phase mixing of soft and hard segment of TPU. The SEM micrograph shows the presence of fibrillar morphology of PDPA molecules in the composite. The ionic conductivity of the swelled composite was 1-fold higher than that of pure TPU. A schematic representation showing the interaction of PDPA molecules with TPU is presented. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 611–617, 2006</P>