Faculty Publications

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    Identification of critical material thickness for eliminating back reflected shockwaves in laser shock peening – A numerical study
    (Elsevier Ltd, 2021) Mylavarapu, P.; Bhat, C.; Perla, M.K.R.; Banerjee, K.; Gopinath, K.; Jayakumar, T.
    Laser Shock Peening (LSP) is one of the emerging surface treatment processes being considered for inducing beneficial compressive surface residual stresses in fatigue critical components. Owing to the ease in handling multiple parameters during optimization of process parameters, simulation based parameterization studies using finite element (FEM) based numerical models are widely gaining importance. Most of the LSP modeling performed so far considered infinite elements in both thickness and lateral directions. However, infinite elements in thickness direction would neglect the deleterious effect of shock wave back reflections for certain sample thicknesses. These back reflections have been reported to result in formation of subsurface cracks in the specimen. Therefore, in this study, using an alternative modeling strategy, effect of thickness on the back reflection of shock waves and its subsequent effect on residual stresses induced are discussed. A 2-D axi-symmetric model with infinite elements in lateral direction and finite elements in thickness direction is developed to simulate a single spot LSP process using ABAQUS/CAE FEM package. It is found that there exists a critical material thickness depending on spot diameter below which the effects of back reflection are predominant. © 2021 Elsevier Ltd
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    Numerical investigation of a novel flow damping device for mitigating liquid sloshing under bi-directional excitation
    (Springer Science and Business Media B.V., 2024) Jogi, P.; Jayalekshmi, B.R.
    Sloshing in liquid storage tanks (LSTs) poses a significant challenge, especially during the seismic events and necessitating the implementation of effective mitigation strategies. This study proposes a novel technique by introducing a flow-damping device (FDD) made up of singly curved cylindrical plates connected to a cylindrical stem. The FDD is designed to be placed inside the LSTs to dissipate seismic energy, thereby reducing sloshing effects. Numerical analysis was conducted using the Arbitrary Lagrangian and Eulerian formulations in ABAQUS to assess the efficiency of various FDD configurations in reducing sloshing displacements in LSTs. The liquid storage tank with and without FDDs, were subjected to uni and bi-directional ground motion records of Imperial valley and Northridge earthquakes with a scaled peak ground acceleration. The study revealed that the FDD configuration consisting of eight plates evenly distributed around the stem with two plates oriented towards each other is the most effective FDD in reducing the seismic response parameters. When the FDD is connected to the tank base and placed centrally inside the tank at a distance of one-sixth of the tank’s length from both ends of the tank wall achieved a maximum reduction of 52.64% in sloshing displacements and 47.99% in impulsive hydrodynamic pressures. These results emphasize the substantial effectiveness of the proposed FDD design in reducing sloshing and hydrodynamic effects in LSTs during seismic events. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.