Papers by Shyamprasad Karagadde
SSRN Electronic Journal
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Acta Materialia
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Lecture Notes on Multidisciplinary Industrial Engineering
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Journal of Materials Processing Technology
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arXiv: Soft Condensed Matter, 2019
In this study, identical experiments of bottom-cooled solidification of water-23 wt% KNO3 and wat... more In this study, identical experiments of bottom-cooled solidification of water-23 wt% KNO3 and water-24 wt% NH4Cl, which exhibit faceted and dendritic microstructures respectively, were performed. The primary objective of this investigation is to understand the role of solidification morphology (mushy zone) and the flow characteristics on the temperature of the bulk fluid. The strength of compositional convection was correlated with the help of Rayleigh number in both mushy and bulk-fluid zones and was further used to assess the flow behaviour during faceted and dendritic growths. Based on the liquid temperature profile during faceted growth, three distinct regimes of heat transfer were observed in the liquid, namely - convection-dominated, transition, and conduction-dominated. The experimental findings revealed an anomalous temperature rise of the bulk liquid when the mushy-zone permeability was restricted by the faceted grain morphology. The observed temperature rise was further as...
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Lecture Notes on Multidisciplinary Industrial Engineering, 2019
The cutting-edge radius of the tool has significant effects on the machining process, as it influ... more The cutting-edge radius of the tool has significant effects on the machining process, as it influences the cutting forces, stresses, and temperature at the tool–chip interface. These parameters ultimately affect the tool life and surface integrity of the finished workpiece. The presence of cutting-edge radius in the tools protects them from easily chipping off during the cutting process. A finite element based ABAQUS™ model is used to evaluate the effect of cutting-edge radius for 20, 40, and 60 μm on the cutting forces for orthogonal cutting of Ti6Al4V alloy at different cutting parameters. It was observed that the cutting-edge radius influences both the cutting and thrust forces. An increase of 4–8% and 12–14% in the cutting force and thrust force was observed when the cutting-edge radius changes from 20 to 60 μm. The temperature in the tool was increased with increasing cutting-edge radius.
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Proceeding of Proceedings of the 25th National and 3rd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2019), 2019
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Procedia Manufacturing
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Metallurgical and Materials Transactions B, 2021
The prediction of precipitated graphite nodules size and distribution in a large industrial casti... more The prediction of precipitated graphite nodules size and distribution in a large industrial casting is critical to understand the mechanical behavior of cast iron components used in heavy vehicles. An accurate prediction of the graphite nodules requires a validated and integrated macro-micro modeling framework, which forms the motivation behind the present study. Classical theories in the literature (Lesoult et al. in Acta Mater 46:983–995, 1998) proposed two stages of graphite growth: in (i) liquid stage, after encapsulation by the austenite grain, and in (ii) solid stage, surrounded by only austenite phase. In this work, a new stage of graphite growth was proposed, where a graphite nodule was in direct contact with the liquid metal, existing in the presence of an austenite grain separated from the nodule. The resulting three-stage graphite growth in a microscopic control volume was formulated using a volume-averaged micro-model. This was made to evolve with the help of a macroscop...
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Scientific Reports
The present work reports real-time observations of the phenomena of partial crystallization of on... more The present work reports real-time observations of the phenomena of partial crystallization of one of the glass-forming materials, namely enstatite (MgSiO3) from its supercooled liquid droplet. Initially, the molten droplet has been held under purely non-contact conditions using the aerodynamic levitation technique. The desired levels of undercooling have been achieved by deliberately making the levitated molten droplet touch a thin molybdenum wire and hence to initiate heterogeneous nucleation from the point of contact. Influence of thermal parameters like undercooling, cooling rates and recalescence on the process of crystallization is investigated. To understand and report the morphological properties and extent of crystallinity, the solidified enstatite samples have been characterized using optical/scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively, which confirmed the formation of partially crystallized enstatite spherules and fully glass spherules. XRD...
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Journal of Fluid Mechanics, 2020
In this study, identical experiments of bottom-cooled solidification fluidic mixtures that exhibi... more In this study, identical experiments of bottom-cooled solidification fluidic mixtures that exhibit faceted and dendritic microstructures were performed. The strength of compositional convection, created due to the rejection of a lighter solute, was correlated with the solidifying microstructure morphology via separate Rayleigh numbers in the mushy and bulk-fluid zones. While the bulk fluid in dendritic solidification experienced a monotonic decrease in the temperature, solidification of the faceted case revealed an unconventional, anomalous temperature rise in the bulk liquid after the formation of a eutectic solid. Based on the bulk-liquid temperatures, three distinct regimes of heat transfer were observed in the liquid, namely, convection-dominated, transition and conduction-dominated. The observations were analysed and verified with the help of different initial compositions and cooling conditions, as well as other mixtures that form faceted morphology upon freezing. The observed...
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A numerical model to study the growth of dendrites in a pure metal solidification process with an... more A numerical model to study the growth of dendrites in a pure metal solidification process with an imposed rotational flow field is presented. The micro-scale features of the solidification are modeled by the well-known enthalpy technique. The effect of flow changing the position of the dendrite is captured by the Volume of Fluid (VOF) method. An imposed rigid-body rotational flow is found to gradually transform the dendrite into a globular microstructure. A parametric study is carried out for various angular velocities and the time for merger of dendrite arms is compared with the order estimate obtained from scaling.
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SSRN Electronic Journal
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Materials Characterization
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Physics of Fluids
Development and proposition of a numerical model to capture the shrinkage induced flow during dir... more Development and proposition of a numerical model to capture the shrinkage induced flow during directional solidification of a pure substance in a bottom cooled cavity are carried out. A novel numerical scheme involving fixed grid-based volume fraction updating is proposed to track the solid–liquid interface, considering the inclusion of the shrinkage effect. Directional solidification in bottom cooled orientation is of particular interest since shrinkage and buoyancy effects oppose each other. The results from the proposed numerical model indicated the existence of an unprecedented flow reversal phenomenon during the progression of the solidification process, caused by the opposing nature of shrinkage and buoyancy effects. The flow reversal phenomena predicted by the numerical model are validated by conducting experiments involving directional solidification of coconut oil in a bottom cooled cavity. Qualitative and quantitative measurements of the velocity field and interface growth are obtained using the particle image velocimetry technique and compared with three dimensional numerical results. Once the flow reversal phenomena are established through numerical and experimental evidences, case studies are performed, considering varying material properties, cold boundary temperatures, initial temperatures of the melt, and cavity heights to find the effect of each of these parameters on flow reversal phenomena. The parametric study also allowed us to check the robustness and consistency of the proposed model. The proposed model will serve as an important milestone toward the development of numerical models for capturing macro-scale shrinkage defects and prediction of composition heterogeneity during directional alloy solidification.
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Journal of Fluid Mechanics
Solidifying ternary systems can exhibit complex natural convection phenomena, particularly due to... more Solidifying ternary systems can exhibit complex natural convection phenomena, particularly due to the presence of two porous zones (cotectic and primary mush), and the rejection of two differently dense solutes. The primary objectives of this study are to investigate the following: (i) the natural convection patterns in various compositional regimes of a typical ternary system, and (ii) the role of the combined existence of the microstructure (facets and dendrites) in the porous zone on natural convection, with a motivation to enhance the current understanding of the microstructure–convection relationships. A ternary mixture is chosen such that different compositions of the three primary solidifying components lead to the formation of distinct ice, dendritic and faceted solid structures that cover the complete span of microstructure–convection relationships. The observations of flow in different compositional regimes show convection occurring in the form of plumes, random mixing and...
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Procedia Manufacturing
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International Journal of Mechanical Sciences
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Journal of Manufacturing Science and Engineering
Direct laser metal deposition (DLMD) is a promising additive manufacturing technique which has a ... more Direct laser metal deposition (DLMD) is a promising additive manufacturing technique which has a huge potential in remanufacturing and restoration of high-value dies/molds and aerospace components. The residual stresses developed in the material deposited via DLMD affect the structural integrity of the restored components. The service life of the restored component will be compromised if tensile residual stresses are present in the deposited layer. The residual stresses originate due to differential thermal expansion/contraction and martensitic transformation-driven volumetric dilation and transformation-induced plasticity. The influence of martensitic transformation and processing conditions on the residual stresses of DLMD-processed components needs to be understood and modeled for sustainable repair. Hence, a finite element model has been developed to capture the coupled effect of thermomechanics and martensitic transformation on the evolution of residual stresses in DLMD. In thi...
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Papers by Shyamprasad Karagadde