Faculty Publications
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Item Wear study and EHD lubrication analysis on connecting rod big end bearings of off-highway application engine(John Wiley and Sons Ltd vgorayska@wiley.com Southern Gate Chichester, West Sussex PO19 8SQ, 2020) Nayak, N.; Rane, S.; Anarghya, A.; Kushwaha, R.The connecting rod big end bearings are under dynamic lubrication during working cycle, and in most of the time, the con rod is subjected to compressive stress. The conventional method of performing an EHL analysis on a bearing involves development of complex mathematical equations and simplification of actual physical model. This paper presents a methodology to model and simulate the elastohydrodynamic lubrication and wear study of connecting rod big end bearings of off-highway application engine using the application of computational fluid dynamics (CFD) and computational structural dynamics (CSD) approaches. The pressure field for a full journal bearing operating under laminar flow regime with various eccentricities was obtained by CFD, and fluid pressure distribution and deformation in the bearing liner due to pressure were evaluated using FSI approach. Relevant parameters of lubrication characteristics were analyzed to optimize the eccentricity value. The maximum bearing load value of 21 kN was noticed at TDC position for the optimum eccentricity. The load distribution indicated critical points in the bearing, and the data obtained from bearing load and sliding velocity of journal were used in Archard's wear relation to determine the wear depth along the bearing width. The simulated wear results were compared with three-cylinder off-highway application engine con rod big end bearings, which ran for 1000 hours at full load condition, and satisfactory agreement was observed between experiment and simulation values. © 2020 John Wiley & Sons, LtdItem A Novel Single-Layered Dual-Wideband Circularly Polarized Asymmetric Slot Antenna for Wireless Applications(Electromagnetics Academy, 2024) Shankaraiah, P.H.; Shet, N.S.V.; Kandasamy, K.This work focuses on the design and implementation of a dual-wideband asymmetric square-shaped slot radiator with coplanar waveguide (CPW) feed for circular polarization (CP) characteristics. The proposed radiator has inward ground plane extensions in the form of square and rectangular strips on the diagonal corners of the slot. By optimizing the size of strips, a dual-band antenna with CP behaviour is obtained. The inverted L-shaped grounded strip improves axial ratio bandwidth (ARBW). The extended signal line terminated in a wide tuning stub significantly improves impedance bandwidth (IBW) and also further enhances ARBW. The designed asymmetric slot radiator is fabricated using an FR-4 substrate material of dimensions 50×50×1.6 mm3. This antenna design gives flexibility to alter polarization sense at the dual frequency bands. Further, edge effects are analyzed through electric field distribution, and their impact on impedance and AR characteristics are studied. It is designed, fabricated, and tested, and shows right-hand circular polarization (RHCP) response at 3 GHz and 7.5 GHz in the +Z direction. The experimentally verified results show −10-dB IBWs of 40.12% (range from 2.61 GHz to 3.92 GHz) and 40.21% (range from 6 GHz to 9.02 GHz), and 3-dB ARBWs are 20% (range from 2.70 GHz to 3.30 GHz) and 40.21% (range from 6 GHz to 9.02 GHz) at the resonance bands. The experimentally measured and simulated performance parameters of the prototype are in close agreement. The proposed perturbed slot radiator is well suited for Wi-Fi 6E communication and remote sensing applications. © 2024, Electromagnetics Academy. All rights reserved.Item Impact Energy Estimation of AISI304L/AA6063 Alloys Dissimilar Friction Welds Influenced by Various New Faying Surfaces: A Comparative Study(Springer, 2024) Senthil Murugan, S.S.; Paulraj, P.; Kattimani, S.This research paper delves into an innovative approach for enhancing the faying surfaces in the rotary friction welding process. This study evaluates the impact energy in Joule (J) of friction-welded joints (FWJs) between dissimilar cylindrical rods made of AA6063 wrought aluminium and AISI304L austenitic stainless steel focusing on the influence of various faying surface designs and welding parameters. Additionally, the study conducts an in-depth analysis of various faying surface designs. A series of experiments were conducted using a Charpy V-notch tester to analyse 45 different FWJs with diverse surface modifications. Welding conditions such as friction pressure (FP), friction time, and upset pressure were varied to assess their effects on joint toughness. The aim was to utilize the low FP, spanning from 1.2 to 1.8 MPa, in the pursuit of optimizing the welding process. The results revealed notable variations in the impact energy values of FWJs in response to changes in both the faying surfaces of the specimens and the welding parameters. A5 trial achieved the highest impact energy at 38 J. Notably, joints with hemispherical faying surfaces exhibited enhanced toughness, with method N achieving 26 J. Adjustments to the faying surface design and welding conditions had a substantial impact on the toughness and energy absorption of the welded joints. © The Institution of Engineers (India) 2024.Item Performance enhancement in polymer electrolyte membrane fuel cell with flow traps and field gradients: A Numerical Study(Elsevier Ltd, 2024) Padavu, P.; Koorata, P.K.; Kattimani, S.; Gaonkar, D.N.Efficient reactant distribution and water removal are critical during polymer electrolyte fuel cell (PEFC) operation. The bipolar plate and its corresponding flow field design are vital among the PEFC components for enhancing reactant transport and water removal. The issues arising in the PEFC during the high current operation, such as reactant starvation and water removal, can be alleviated by improving the flow channel geometry. In this study, we analyze the variation in overall PEFC performance and corresponding reactant transport phenomenon for two independent design cases. The converging gradient design without channel traps at 0.4 V operating voltage exhibited a current density increment of 6.85% against the conventional design. Moreover, at 0.4 V, including channel traps enhanced the current density, as we observed a current density increment of 7.1% for the converging design with channel traps against the conventional design without channel traps. Likewise, at 0.4 V, the diverging design with channel traps exhibited a current density increment of 5.85% against the diverging design with no channel traps. Further, enhanced reactant distribution is observed in the catalyst layer upon introducing channel traps in the flow field design. © 2024 Hydrogen Energy Publications LLCItem Torque generation in lightweight four rotor magnetorheological brake(Springer, 2024) Kadam, S.; Kariganaur, A.K.; Kumar, H.Non-Newtonian behaviour of the Magnetorheological (MR) fluid under the influence of external magnetic field can be commissioned to design various applications such as MR brake, damper, and clutches, etc. Better design strategies, material selection and characterization led to realize the potential of MR brakes to replace conventional brakes. The present study emphasises on developing lightweight (1.8 kg) multi-rotor MR brake (MMRB). Finite element method magnetics (FEMM) software is utilized to determine the material required for a single-rotor MRB. FEMM material selection analysis is incorporated into the modeled MMRB, and the nature of magnetic flux density throughout the MR gap was obtained. Magnetic circuit analysis of the proposed brake is carried out to find torque estimation using analytical equations and Bingham plastic model. The proposed brake is fabricated and characterized using commercial MRF (132 DG, Lord Corporation). The study compares the torque outputs obtained experimentally with finite element analysis (FEA) and analytical approach. The average maximum magnetic flux density through FE analysis is found to be 0.45 T @ 3 A current. The average error between FE obtained and experimentally obtained torque output of the brake is around 5%. Further, an alternate design is proposed by utilizing same rotor diameter and number of electromagnetic coils. The new design is lighter in weight (0.8 kg) and exhibits enhancement in the torque output and torque to weight ratio by around 31% and 55%, respectively than the present design. © Indian Academy of Sciences 2024.Item Flutter prediction for unmanned long endurance aircraft using virtual structural model and experimental modes(SAGE Publications Ltd, 2025) Sampath, A.K.; Kattimani, S.Aeroelastic stability is an important consideration in the design and certification processes of modern, flexible aircraft. This includes demonstration of freedom from flutter at all combinations of airspeed and altitude within the flight envelope. This paper presents the analysis and clearance of flutter characteristics for an unmanned medium altitude long endurance aircraft by two distinct methods. The traditional method based on a theoretical Finite Element (FE) model was adopted prior to the conduct of Ground Vibration Tests (GVT) where as the more recent method utilized a Virtual Structural Model (VSM) built on the experimental modal parameters that were obtained from the GVT. The Direct Matrix Abstraction Program (DMAP) feature of MSC NASTRAN was used to create the VSM whose nodes correspond to the GVT accelerometer locations, and to insert the GVT modes into the model. In both approaches the unsteady airloads were generated using the Doublet Lattice Method (DLM). The GVT/VSM based analyses closely mirrored the original FE model analysis and confirmed the existence of sufficient flutter margins, thereby enabling the flight certification of the aircraft. The VSM route to flutter analysis is outlined in this paper as an alternative to using a GVT-tuned FE model. This is beneficial (i) if no FE model is available as it happens with bought out aircraft, or (ii) if the configurations of interest are too few to justify the effort of FE model tuning. © IMechE 2025Item Predicting joint shear in beam–column connections using convolutional neural networks(Springer Science and Business Media B.V., 2025) Sidvilasini, S.; Palanisamy, T.Predicting joint shear at beam-column junctions (BCJ) is essential in structural engineering to ensure the safety and reliability of systems. Current methodologies using empirical calculations may rely on simplistic assumptions and insufficiently account for the many geometric factors and material properties that influence shear in BCJ. This research introduces a novel approach using Convolutional neural networks (CNNs) to predict joint shear. The collection comprises 515 joints, categorized into 210 exterior joints and 305 interior joints, characterized by 14 fundamental factors delineating their form and material properties. The predictive performance of the CNN model has been evaluated using known engineering codes, including ACI 318-19, NZS 3101:1-2006, IS 13920:2016, and several other data-driven models in the domain. Furthermore, it has been contrasted with an ensemble regression method. The study includes a thorough sensitivity analysis using a gradient-based method to determine the relative importance of input factors in predicting shear stress. The findings demonstrate the effectiveness of CNN in identifying complex relationships among joint parameters, thereby enabling precise predictions of joint shear. This method offers a promising alternative to traditional empirical formulas and enhances the understanding of structural behavior in BCJ. This study integrates contemporary machine learning algorithms with structural engineering concepts to optimize design processes and augment the safety and reliability of built environments. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.Item Experimental investigation on a novel base-isolator for ground supported liquid storage tanks(Springer Science and Business Media B.V., 2025) Jogi, P.; Jayalekshmi, B.R.The dynamic analysis of ground-supported rectangular liquid storage tanks (LSTs) with base isolation, using steel core and filler bearings, is conducted experimentally and numerically through the finite element method. Five types of bearings are designed for the selected tank geometry, namely laminated rubber bearing, sand-filled rubber bearing, coir-filled rubber bearing, steel core-sand filled rubber bearing, and steel core-coir filled rubber bearing. LST models with these bearings are fabricated and tested on a shake table under harmonic motion. The models are also analyzed numerically in ABAQUS using a coupled acoustic-structural approach to examine fluid–structure interaction behaviour and compare with experimental results. Seismic response parameters, including convective displacement, hydrodynamic pressures on the tank wall and base, and bearing displacements, are investigated under harmonic motions. The designed bearings significantly reduce hydrodynamic pressures compared to standard laminated rubber bearings. Specifically, the base isolator with steel core-coir filler reduces the hydrodynamic pressure by more than 86% and the bearing displacement by 96% as compared to non-isolated LSTs. This novel isolation effectively reduces the risk of LST failure under dynamic loads due to its high energy dissipation capacity, effective stiffness, damping, and yield strength, even at low bearing displacements. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.Item Long-term response analysis of hybrid STLP-WEC offshore floating wind turbine(Taylor and Francis Ltd., 2025) Rony, J.S.; Karmakar, D.In the present study, time-domain response analysis of different configurations of a hybrid Submerged Tension Leg Platform (STLP) combined with a Point Absorber-type Wave Energy Converter (WEC) (STLPWEC) is performed using the aero-servo-hydro-elastic simulation. The study employs long-term analysis technique to predict the most probable values of motion amplitudes, and the forces and moments developed at the tower base for the hybrid STLP-WEC system under operational wind speed conditions of the 5 MW wind turbine. The long-term distribution is performed using short-term responses based on Rayleigh distribution and North Atlantic wave data. The performance of the offshore STLP-WEC system depends on both the transfer functions (translational and rotational motions) and the wave spectrum model. A comparative study of the long-term responses using JONSWAP spectrum model for different configurations of the hybrid STLP-WEC systems is performed, providing valuable insights for designing floating hybrid systems. © 2025 Informa UK Limited, trading as Taylor & Francis Group.Item A Fast and Robust PLL Design with a Combination of Frequency-Adaptive Alpha-Beta-CDSC and SOGI(Institute of Electrical and Electronics Engineers Inc., 2025) Mondal, S.; Gayen, P.K.; Gaonkar, D.N.Recent research has focused on the enhancement of the prefiltering capability of phase-locked loops (PLL). The cascaded delayed signal cancellation (CDSC) PLL removes the low-order selective harmonic frequencies near the fundamental frequency. Here, a frequency-adaptive time delay unit is used to cope with frequency and phase variations of voltage. The high-frequency signal arising due to the frequency-adaptive loop cannot be mitigated. In effect, the transient response of adaptive CDSC-PLL shows a significant irregular pattern. Therefore, this article suggests the use of a second-order generalized integrator (SOGI) after the adaptive CDSC unit to improve the transient profile of frequency response. In the design, the high gain (K = 5.4) of SOGI is chosen to quickly settle the response of PLL at the expense of its ignorance of lower-order harmonics near the fundamental frequency. However, the lower-order harmonics are selectively eliminated by the CDSC unit. So, both prefilters complement each other's filtering capabilities. Additionally, the suggested prefilter provides improved noise immunity and eliminates DC offset via the SOGI unit. The linearized model and tuning procedure for the different control parameters of the proposed PLL are described. The real-time hardware-in-loop tests are executed to justify the optimum performance of the proposed PLL. © 2024 IEEE.