Faculty Publications
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Item Wave transformation due to floating elastic thick plate over changing bottom topography(Springer, 2019) Praveen, K.M.; Karmakar, D.In the present study, the wave interaction with floating thick elastic plate is studied over changing bottom topography. The effect of flexible floating plates is studied based on Timoshenko–Mindlin’s theory in finite water depth and shallow water approximations. The hydroelastic analysis is performed at varying water depths and plate sizes to get the behaviour of elastic plate under the action of ocean wave. Different bottom topography cases are considered in the analysis of wave interaction with floating thick elastic plate. A mathematical model considering the mode-coupling relation along with the orthogonality condition is formulated to analyse the wave scattering due to floating thick elastic plate with varying bottom topography. The numerical results for the hydroelastic behaviour are obtained for wave interaction with floating plate with free-edge condition in varying bottom topography. The present analysis helps to understand the significance of rotary inertia and transverse shear deformation for the floating elastic plates. The study provides an insight into the effect of seabed profile over the wave interaction with floating thick elastic plate in finite water depth. © Springer Nature Singapore Pte Ltd. 2019.Item Coupled boundary element method and finite element method for hydroelastic analysis of floating plate(Shanghai Jiaotong University, 2018) Shirkol, A.I.; Nasar, T.In this study, a numerical procedure has been proposed to analyze the equation of motion of the elastic plate which is elastic in nature and having shallow draft (small thickness) with arbitrary geometry subjected to linear wave force at a fixed frequency. Investigation on the convergence of maximum deflection of the floating plate has been carried out. A hybrid model has been developed (coupling between FEM and BEM) which contains same nodes, maintaining the same order and basis function in both the methods. To develop the relationship between the displacement of the plate and the velocity potential under the plate, two equations have been derived. The first equation is derived from the equation of motion for the plate and is solved by finite element method (FEM) to extract the displacement of the floating structure. The second equation is from water wave theory which is based on boundary integral equation that relates the displacement of the floating plate and velocity potential using free-surface Green's function. To get the displacement of floating elastic plate and velocity potential both the equations are solved simultaneously. Results are presented for modified Green's function which has been derived and validated with the results of Meylan (2004). The performance of the developed model is examined by the convergence rate, simulation time. It is learnt that the model works well in finite depth whereas its performance in infinite depth lags by an average of 20% in simulation time than the results obtained by Meylan (2004). © 2017 Shanghai Jiaotong UniversityItem Hydroelastic analysis of articulated floating elastic plate based on Timoshenko–Mindlin plate theory(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2018) Praveen, P.; Karmakar, D.; Guedes Soares, C.G.The wave interaction with articulated floating elastic plate is investigated considering the Timoshenko–Mindlin thick plate theory for both finite and shallow water depths. The elastic plates are modelled as finite flexible floating structure interconnected with vertical linear/rotational spring stiffness. The eigenfunction expansion method along with the orthogonal mode-coupling relation is used to analyse the hydrodynamic behaviour of the interconnected structure. The study is performed for different articulated edge conditions for varying plate thickness and water depths to understand the behaviour of articulation under the action of an ocean wave. The hydroelastic response of the interconnected floating elastic plate with different connector stiffness is observed to compare well with the result available in the literature. The present study provides an insight into the effect of articulated joints with varying spring stiffness for the suitable design of the structure. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.Item Wave Interaction With Floating Elastic Plate Based on the Timoshenko-Mindlin Plate Theory(American Society of Mechanical Engineers (ASME) infocentral@asme.org, 2019) Praveen, K.M.; Karmakar, D.; Guedes Soares, C.In the present study, the wave interaction with the very large floating structures (VLFSs) is analyzed considering the small amplitude wave theory. The VLFS is modeled as a 2D floating elastic plate with infinite width based on Timoshenko-Mindlin plate theory. The eigenfunction expansion method along with mode-coupling relation is used to analyze the hydroelastic behavior of VLFSs in finite water depth. The contour plots for the plate covered dispersion relation are presented to illustrate the complexity in the roots of the dispersion relation. The wave scattering behavior in the form of reflection and transmission coefficients are studied in detail. The hydroelastic performance of the elastic plate interacting with the ocean wave is analyzed for deflection, strain, bending moment, and shear force along the elastic plate. Further, the study is extended for shallow water approximation, and the results are compared for both Timoshenko-Mindlin plate theory and Kirchhoff's plate theory. The significance and importance of rotary inertia and shear deformation in analyzing the hydroelastic characteristics of VLFSs are presented. The study will be helpful for scientists and engineers in the design and analysis of the VLFSs. © 2019 by ASME.Item Coupled BEM and FEM for the analysis of floating elastic plate with arbitrary shapes(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2019) Shirkol, A.I.; Nasar, T.In order to analyse the hydroelastic behaviour of the floating thin elastic plate, a numerical model has been developed by coupling higher-order boundary element method (BEM) and finite element method (FEM). The present model is capable of investigating the very large floating structure of arbitrary shapes at finite and infinite water depths. The developed hybrid model contains the same nodes maintaining the same order and basis function in both the methods. The novelty of this work can be seen in the newly developed modified Green’s function. Two geometrical configurations (triangle and trapezoidal) have been analysed. The time required for convergence and deflection of the geometrical model have been captured. Furthermore, the results obtained by Wang and Meylan [2004. A higher-order-coupled boundary element and finite element method for the wave forcing of a floating elastic plate. J Fluids Struct. 19(4):557–572] are used to validate the developed numerical model. It is concluded that the model works better in finite water depth for trapezoidal shape. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.Item Hydroelastic analysis of a truss pontoon mobile offshore base(Techno Press technop2@chollian.net, 2019) Sakthivel, S.; Panneer Selvam, R.; Karmakar, D.Very Large Floating Structures (VLFS) are one among the solution to pursue an environmentally friendly and sustainable technology in birthing land from the sea. VLFS are extra-large in size and mostly extra-long in span. VLFS may be classified into two broad categories, namely the pontoon type and semi-submersible type. The pontoon-type VLFS is a flat box structure floating on the sea surface and suitable in regions with lower sea state. The semi-submersible VLFS has a deck raised above the sea level and supported by columns which are connected to submerged pontoons and are subjected to less wave forces. These structures are very flexible compared to other kinds of offshore structures, and its elastic deformations are more important than their rigid body motions. This paper presents hydroelastic analysis carried out on an innovative VLFS called truss pontoon Mobile Offshore Base (MOB) platform concept proposed by Srinivasan and Sundaravadivelu (2013). The truss pontoon MOB is modelled and hydroelastic analysis is carried out using HYDRAN-XR*for regular 0°waves heading angle. Results are presented for variation of added mass and damping coefficients, diffraction and wave excitation forces, RAOs for translational, rotation and deformational modes and vertical displacement at salient sections with respect to wave periods. © 2019 Techno-Press, Ltd.Item Hydroelastic analysis of periodic arrays of multiple articulated floating elastic plate(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2020) Praveen, K.M.; Karmakar, D.; Guedes Soares, C.The periodic array of multiple articulated floating elastic plate acted upon by ocean waves is analysed considering Timoshenko-Mindlin plate theory. The floating elastic plate is placed periodically and is interconnected with vertical linear and flexural rotational springs which acts as an articulated joint. The hydroelastic behaviour of multiple articulated floating elastic plate is analysed based on eigenfunction expansion method along with the orthogonal mode-coupling relation in finite water depth and the continuity of energy and mass flux are used in the hydroelastic analysis of floating plate at shallow water depth. Further, the application of the wide-spacing approximation (WSA) method is employed to analyse the hydroelastic characteristics of the multiple articulated floating elastic plate. The results obtained using the eigenfunction expansion method is compared with the results based on WSA at finite water depth and validated with the results available in the literature. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.Item Hydroelastic response of floating elastic plate in the presence of vertical porous barriers(Taylor and Francis Ltd., 2022) Praveen, K.M.; Venkateswarlu, V.; Karmakar, D.The attenuation of the incident wave interacting with a very large floating structure (VLFS) in the presence of vertical barriers is analysed considering small amplitude wave theory. The VLFS is considered to be articulated and is modelled based on Timoshenko-Mindlin plate theory. The eigenfunction expansion method along with the orthogonal mode-coupling relation is employed for the case of finite water depth. The numerical study is performed to analyse the wave reflection, transmission and dissipation characteristics due to the articulated floating plate for the case of bottom standing and surface piercing vertical porous barriers. The hydroelastic behaviour in terms of deflection and strain for an articulated floating thick elastic plate in the presence of porous barriers is analysed. The study reveals that the magnitude of wave attenuation is enhanced due to the presence of vertical porous barriers and also provides an understanding in mitigating the structural response. © 2020 Informa UK Limited, trading as Taylor & Francis Group.Item Wave transformation due to finite floating elastic plate with abrupt change in bottom topography(Taylor and Francis Ltd., 2022) Praveen, K.M.; Venkateswarlu, V.; Karmakar, D.The propagation of surface gravity waves in the presence of finite floating elastic plate over varying sea bottom profile is investigated using the Timoshenko-Mindlin plate theory. The continuity of velocity and pressure at the interfaces along with the continuity of deflection, slope, bending moment and shear force is employed with the support conditions at the plate edges. The numerical computation is performed to obtain the hydroelastic behaviour of the floating elastic plate due to abrupt change in bottom topography. The validation of the present analytical model is performed with the known results available in the literatures. Further, a detailed comparison of the numerical results is presented for different step bottom topography on the hydroelastic characteristics of a floating elastic platform. The present study will provide an insight into the effect of the ocean bottom profile on wave propagation due to the presence of a large floating elastic plate. © 2021 Informa UK Limited, trading as Taylor & Francis Group.Item Investigation of phase transformation and mechanical properties of silicon addition on AlCrFeMnNi high entropy alloys(Institute of Physics, 2024) Chandrakar, R.; Chandraker, S.; Kumar, A.; Jaiswal, A.This paper examines the impact of silicon in the AlCrFeMnNi high-entropy alloy system, focusing on both its microstructural and mechanical properties. Alloys with varying silicon content (x = 0, 0.3, 0.6, 0.9 atomic ratio) were synthesized using vacuum arc melting. The phase formation of these high-entropy alloys was analyzed using x-ray diffraction to comprehend the alloying process behaviour. The findings revealed that the solidification of the AlCrFeMnNi alloy occurred in dendritically, with dendrite cores containing Cr, Fe, and Ni, while interdendritic regions were enriched in Al and Ni after adding Silicon. Increasing the silicon content from 0 to 0.9 led to significant improvements in microhardness and wear resistance. This improvement is attributed to the reinforcement of grain boundaries provided by silicon. The formation of an Al and Ni rich B2 phase is crucial in resisting dislocation motion and preventing further deformation. Additionally, the addition of silicon led to improved corrosion resistance, as demonstrated by potentiodynamic polarization measurements. However, a trade-off was observed between compressive strength and ductility: compressive strength increased with higher silicon concentrations, but at the expense of ductility. © 2024 The Author(s). Published by IOP Publishing Ltd.