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Karmakar, Nilankan
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Effectiveness of Power-Law Profile Indentations on Structure-Borne Noise

General Motors-Jeffrey Curtis
General Motors Technical Center India-Pranoy Sureshbabu Nair, Nilankan Karmakar, Seshagiri Rao Maddipati
Published 2019-06-05 by SAE International in United States
A study on the effect of indenting power-law shaped profiles on the flexible structures for investigating the vibration damping characteristics using computational simulation method is discussed. The simulation results are checked to see the impact of such features on the damping behavior of flexible structures responsible for radiating noise when excited with fluctuating loads. Though the conventional remedies for solving Noise and vibration issues generally involves tuning of structure stiffness or damping treatment this paper gives an insight on the idea of manipulation of elastic waves within the flexible structure itself to minimize the cross-reflections of the mechanical waves. The simulation studies mentioned in this paper not only hovers over the effectiveness of such features but also will be helpful for the engineers to look through a different perspective while solving N&V issues using simulation tools. In this paper, different studies are discussed to see the impact of such features on the damping effect of the vibrating structure comparing mobility response and far-field sound pressure response as well. Propagation of waves within the structure is…
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Simulation Methodology to Study the Effect of Fluid-Structure Interaction on Dynamic Behavior of Flexible Pipes

General Motors Technical Center-Pranoy Sureshbabu Nair, Nilankan Karmakar
Published 2019-04-02 by SAE International in United States
A numerical simulation methodology that enables assessment for the impact of fluid flow on the slender piping system’s dynamics has been discussed in this paper. The fluid-structure interaction involves many different complex phenomena like water hammer, cavitation which can also affect the dynamics of the overall system but this paper highlights on the influence of fluid flow velocities and piping designs on dynamic responses of the system. A co-simulation between structure and fluid dynamics is performed in Abaqus to evaluate the dynamic behavior of the piping system. The flexible pipes are excited with dynamic loads capturing the modal behavior of the system and displacements are considered as a measure for relative comparison. The free vibration response, after the removal of load, is also used to evaluate the damping characteristics of the overall system subjected to different fluid flow conditions. The main objective of this method is to provide an opportunity for the analysts to come up with alternate ways to capture the variation in responses in time domain simulations and to account for such changes…
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Prediction of Secondary Dendrite Arm Spacing in Directional Solidification of Aluminum Alloy by Casting Simulation and Micro-Structural Inspection

General Motors Global Propulsion System-Pankaj Jha, Michael Nienhuis
General Motors Technical Center India-Nilankan Karmakar, Sudipto Ray, Neeraj Carpenter, Akshay A., Virupakshappa Lakkonavar
Published 2019-01-09 by SAE International in United States
In automotive industry, many of the powertrain components (for e.g. engine head and cylinder block) are generally manufactured by a casting procedure. Secondary Dendrite Arm Spacing (SDAS) is one of the most important microstructural features in dendritic solidification of alloys (for e.g. Al-Si alloys) during the casting process. SDAS has a significant influence on the mechanical behavior of the cast aluminum components. A lower value of SDAS is desired in order to achieve better fatigue strength of the cast components which can be controlled by governing several casting parameters. For directional solidification, SDAS is dependent on various casting parameters i.e. chemical composition of the alloy, cooling rate and liquid melt treatment. During industrial casting of an alloy with predefined chemical composition, cooling rate during the mushy zone becomes the dominant parameter for controlling SDAS. The objective of this study was to predict the SDAS of die cast Al-Si alloy samples subjected to different cooling rates by varying the mold temperature. The SDAS was predicted by a casting simulation and utilizing the empirical relationship between solidification…
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