Faculty Publications
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Publications by NITK Faculty
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Item Experimental analysis of thermally induced motion of U-tubes(Springer Science and Business Media, LLC, 2008) Malik, P.The present article focuses attention on the effect of thermal load on dynamic response of the thin U-tubes. Experimental studies are carried out on thermally induced vibration of internally heated cantilevered U-tube. The dynamic response of the tube is studied in lateral and transverse direction for varying heating rates and frequencies. The analysis showed that the rate of vibration is governed by the heating rate and natural frequency of the tube. Lower the heating rates larger are the time to attain steady state amplitude and vice versa, there exist a threshold heating rate to produce thermal induced motion for tube. Displacement response of the U-tube in the lateral direction, during the initial period of the tube motion, occurred in the first mode and with progress of time the displacement response changed to second mode with amplitude of vibrations being lower than that observed in first mode. © Springer Science + Business Media B.V. 2008.Item Numerical Simulations for Seismic Response of Laterally Loaded Pile Foundation(Springer Science and Business Media Deutschland GmbH, 2024) Barik, T.; Chaudhary, B.Pile foundations are frequently used to safely transfer enormous loads from superstructures to deeper soil layers in order to support structural weight. Due to earthquakes, piles are subjected to dynamic loadings, which causes significant damage to the foundation as well as the superstructure. Laterally loaded piles vulnerable to earthquakes have a complex dynamic reaction. Earthquake motions shake the foundation ground which can make it unstable. Due to this unpredictable behaviour, the research has been carried out for the last few decades on it but still the behaviour is not understood completely. Therefore, an attempt has been made in this study to investigate the dynamic response of the pile foundation due to earthquakes by performing numerical study using Finite Element (FE) program, PLAXIS 3D. In addition to it, several parameters have been studied to understand the effects of several parameters like soil properties, earthquake features (acceleration, frequency etc.) on pile behaviour, considering soil-pile interaction. It can be stated that this numerical simulation will be useful for the researchers and practicing engineers working on this domain. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.Item Seismic Analysis of Piled-Raft Foundations in Mid-Rise Buildings on Soft Soil(Springer Science and Business Media Deutschland GmbH, 2024) Amalu, P.A.; Jayalekshmi, B.R.The utilization of piled-raft foundations is prevalent in buildings constructed on soft soil to mitigate settlement and increase bearing capacity. Nevertheless, if dynamic loading is not suitably considered during the design phase, these foundations may fail. This investigation utilizes three-dimensional finite element analyses in OpenSees to explore the seismic behaviour of mid-rise buildings with piled-raft foundations founded on soft soil. The principal focus of this study is on the influence of soil-foundation-structure interactions (SFSIs) under earthquake loadings. For this purpose, the El-Centro 1979 earthquake was used as the base acceleration underneath the soil layer to simulate the seismic conditions. The study scrutinizes the influence of pile flexural rigidity and superstructure configuration (G + 2, G + 4, G + 7) on the responses of mid-rise buildings on piled-raft foundations under earthquake loading. The findings revealed that buildings with a higher number of floors exhibit larger inter-storey drift with consideration of SFSI. Additionally, an increase in pile flexural rigidity significantly diminishes lateral displacements and shear force during earthquake loading. This study highlights that the flexural rigidity of pile and superstructure configuration are two pivotal factors that determine the response of piled-raft foundations of mid-rise buildings under earthquake loading. Proper consideration of these factors during the design phase can help mitigate the risk of failure and improve the performance of buildings with piled-raft foundations founded in soft soil. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.Item Dynamic response of railroad vehicle to rail joints and average vertical profile: A time domain approach(Inderscience Publishers, 2007) Gangadharan, K.V.; Sujatha, C.; Ramamurti, V.One rigid body and three finite element models have been used to study the dynamic behaviour of a typical Electrical Multiple Unit Trailer coach running on Indian suburban tracks. Following eigenvalue analysis, dynamic responses to input excitation from rail joints and Average Vertical Profile (AVP) have been determined in the time domain, using mode superposition technique. Acceleration and displacement response at Centres of Gravity (eg) of car and bogie have been predicted. The analytical results compare well with experimental results and highlight the need to include superstructure elasticity to predict the dynamic response accurately. Copyright © 2007 Inderscience Enterprises Ltd.Item Free vibration studies of box type laterite masonry structures(2012) Unnikrishnan, S.; Narasimhan, M.C.; Venkataramana, K.Box-type laterite masonry structures are widely seen in south-west coastal areas of India. Not many studies are available in the literature on the dynamic response of such structures. Free vibration analysis of box-type laterite masonry structures has been attempted in this study, as a preliminary to a detailed dynamic analysis. Finite element analysis has been conducted to And the natural frequencies and corresponding mode shapes of box-type laterite masonry buildings. Results of detailed parametric studies conducted to find the effect of various parameters like modulus of elasticity of laterite masonry, provision of a lintel band or a roof slab, openings in long walls and aspect ratio on the natural frequencies and their mode shapes of box-type laterite masonry buildings are presented and discussed in this paper.Item Vibration analysis of a tapered laminated thick composite plate with ply drop-offs(Springer Verlag service@springer.de, 2015) Edwin Sudhagar, P.; Arumugam, A.; Vasudevan, R.; Jeyaraj, J.In this study, vibration characteristics of a tapered laminated thick composite plate have been investigated using finite element method by including the shear deformation and rotary inertia effects. The governing differential equations of motion of a tapered laminated thick composite plate are presented in the finite element formulation based on first-order shear deformation theory for three types of taper configurations. The effectiveness of the developed finite element formulation in identifying the various dynamic properties of a tapered laminated thick composite plate is demonstrated by comparing natural frequencies evaluated using the present FEM with those obtained from the experimental measurements and presented in the available literature. Various parametric studies are also performed to investigate the effect of taper configurations, aspect ratio, taper angle, angle ply orientation and boundary conditions on free and forced vibration responses of the structures. The comparison of the transverse free vibration mode shapes of the uniform and tapered composite plates under various boundary conditions is also presented. The forced vibration response of a composite plate is investigated to study the dynamic response of tapered composite plate under the harmonic force excitation in various tapered configurations. It is concluded that the dynamic properties of laminated thick composite plates could be tailored by dropping off the plies to yield various tapered composite plate. © 2015, Springer-Verlag Berlin Heidelberg.Item Influence of Material and Geometrical Properties on Static and Dynamic Behavior of MR Fluid Sandwich Beam: Finite Element Approach(Institute for Ionics, 2023) Nagiredla, S.; Joladarashi, S.; Kumar, H.Magnetorheological (MR) fluid can transform its rheological properties when it is exposed to a magnetic field. This nature of the MR fluid provides an additional stiffness and damping for the sandwich beam applications. The Lagrange’s method is used to derive the equations of motion for the current finite element formulation. The influence of an applied magnetic field, thickness ratio and the length parameter on the static deflection, loss factor and natural frequency for different boundary conditions are presented. Further, the study is extended to plot the real and imaginary mode shapes corresponding to the fundamental frequencies. The geometrical and material properties considered in the present study showed a significant influence on static deflection and vibration amplitude of the sandwich beam. There is a maximum of 22.74% decrease in static deflection obtained for the simply supported condition. © 2023, The Author(s), under exclusive licence to Shiraz University.Item Modelling and predicting the dynamic response of an axially graded viscoelastic core sandwich beam(KeAi Communications Co., 2023) Nagiredla, S.; Joladarashi, S.; Kumar, H.The present study explored the influence of axial gradation of viscoelastic materials on the dynamic response of the sandwich beam for structural applications. The finite element (FE) formulations are used to model and investigate dynamic response of the sandwich beam. The classical beam theory is used to develop the FE formulations and Lagrange's approach is considered to obtain the equations of motion (EOM). FE code is developed and validated with the existing literature and also conducted the convergence study for the developed FE method. Further, the influence of different viscoelastic materials and boundary conditions on the dynamic response of the sandwich beam is investigated. Four different axial gradation configurations of viscoelastic materials are considered for the present work to explore the influence on natural frequency, loss factor and frequency response of the sandwich beam. The modeled axial gradation of viscoelastic material has displayed a considerable impact on the peak vibrational amplitude response of the sandwich beam for all the boundary conditions and these configurations improved the damping capabilities at different configurations for the structural applications. © 2023 China Ordnance SocietyItem Influence of magneto-rheological fluid pocket configuration on the dynamic response of the composite sandwich beam(Taylor and Francis Ltd., 2024) Nagiredla, S.; Joladarashi, S.; Kumar, H.The present study investigated the influence of magnetorheological (MR) fluid pocket configuration and magnetic field intensity on the dynamic response of the composite sandwich beam under various boundary conditions. The classical beam theory is used to develop the finite element (FE) formulations for the composite sandwich beam element and it is validated with the available literature. Four MR fluid pocket configuration types are considered. The configuration types include 1/4th, 1/2th, 3/4th and the full length of the MR fluid pockets at different locations. Further, a detailed study of the influence of each MR fluid pocket configuration type on the natural frequency, loss factor, and frequency response are presented. The maximum 32.27% of deviation in the first fundamental frequency is observed for the simply-supported boundary condition. From the results obtained, it is concluded that the length and location of the MR fluid pocket have a considerable impact on the dynamic response and also observed that the effect of the configuration depends on the type of boundary condition used. © 2022 Taylor & Francis Group, LLC.Item Dynamic analysis of frustum TLP-type wind turbine multi-purpose floating platform(Taylor and Francis Ltd., 2024) Rony, J.S.; Karmakar, D.The coupled dynamic analysis of a hexagon-shaped Frustum Tension-leg platform (FTLP) combined with wave energy converters (WECs) supporting a 5-MW wind turbine is performed to analyse the dynamic responses of the hybrid system. The responses of the FTLP are investigated using the time-domain numerical simulation for the operational sea-states of the wind turbine. The FTLP is integrated with an array of point absorber-type WECs in a circular pattern to analyse the influence of the WECs on the dynamic responses of the floating platform. The aero-servo-hydro-elastic simulation tool FAST and hydrodynamic simulation tool WAMIT is used to study the rigid body motions of the system. The study observes higher rigid body motions in the surge, sway and yaw directions for the hybrid system. Further, the investigation is performed for the forces and moments developed at the base of the wind turbine and the tension developed on mooring cables to understand the integrity and stability of the hybrid platform. © 2023 Informa UK Limited, trading as Taylor & Francis Group.