Faculty Publications
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Item Transverse stresses in antisymmetric angle ply sandwich plates - Analytical evaluation of refined higher order shear deformation theories(2010) Swaminathan, K.; Sangwai, G.R.In the present work two higher order computational models with 9 and 12 DOF already available in the literature for which analytical formulations and solutions for the stress analysis not yet reported are considered. In addition to these models, few higher order models and the first order model developed by other investigators are also considered for the evaluation. A simply supported plate subjected to sinusoidal transverse load with SS-2 boundary conditions is considered for the analysis. Solutions are obtained using Navier's technique. Transverse stresses are computed by post processing technique and the accuracy of models in predicting the stresses is evaluated. © (2010) Trans Tech Publications.Item Isogeometric Analysis of Composite Sandwich Plates Using Equilibrium-Based Stress Recovery Procedure(Springer Science and Business Media Deutschland GmbH, 2023) Chethan, J.; Pavan, G.S.Composite sandwich plates consist of a core and face sheets on the top and bottom.Accurate determination of three-dimensional stress states in sandwich plates by numerical approach requires the adoption of 3D finite element (FE) modeling or FE modeling based on layer-wise theories.Though both these numerical approaches give accurate results, they are computationally expensive.This study introduces an equilibrium-based stress recovery approach for determining three-dimensional stress state in composite sandwich plates subjected to transverse loading.This numerical approach is a two-part process, with the initial step based on the concept adopted by layer-wise theories, and the second step is a post-processing procedure.For approximating the unknown field variables, this computational approach employs non-uniform rational B-splines (NURBS).NURBS functions offer the flexibility of a higher degree of inter-element continuity.The study has adopted numerical examples based on the bending of sandwich plates under a sinusoidal load and an evenly distributed load with different edge conditions.Results obtained were compared with the 3D FE method and layer-wise theories and were found to be accurate.In comparison to the 3D FE method and the layer-wise approach, the study reveals that the proposed strategy can provide correct findings with a substantially lesser number of degrees of freedom. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Analytical formulations and solutions to the static analysis of simply supported anti-symmetric angle-ply composite and sandwich plates hitherto not reported in the literature based on a higher-order refined theory already reported in the literature are presented. The theoretical model presented herein incorporates laminate deformations, which account for the effect of transverse shear deformation and a non-linear variation of in-plane displacements with respect to the thickness coordinate. The transverse displacement is assumed to be constant throughout the thickness. The equations of equilibrium are obtained using principle of minimum potential energy. Solutions are obtained in closed form using Navier's technique by solving the boundary value problem. Accuracy of the theoretical formulations and the solution method is first ascertained by comparing the results with that already reported in the literature. After establishing the accuracy of the solutions, numerical results with real properties are presented for the multilayer antisymmetric angle-ply composite and sandwich plates, which will serve as a benchmark for future investigations. © 2003 Elsevier Ltd. All rights reserved.(Analytical solutions using a higher-order refined theory for the static analysis of antisymmetric angle-ply composite and sandwich plates) Swaminathan, K.; Ragounadin, D.2004Item Bending of sandwich plates with anti-symmetric angle-ply face sheets - Analytical evaluation of higher order refined computational models(2006) Swaminathan, K.; Patil, S.S.; Nataraja, M.S.; Mahabaleswara, K.S.The aim of the present study is to assess the accuracy of the few computational models based on various shear deformation theories in predicting the bending behaviour of sandwich plates with anti-symmetric angle-ply face sheets under static loading. Five two-dimensional models available in the literature are used for the present evaluation. The performance of the various models is evaluated on a simply supported laminated plate under sinusoidal loading. The equations of equilibrium are derived using the principle of minimum potential energy (PMPE). Analytical solution method using double Fourier series approach is used in conjunction with the admissible boundary conditions. The accuracy of each model is established by comparing the results of composite plates with the exact solutions already available in the literature. After establishing the correctness of the theoretical formulations and the solution method, benchmark results for transverse displacement, in-plane stresses, moment and shear stress resultants are presented for the multilayer sandwich plates. © 2006 Elsevier Ltd. All rights reserved.Item Analytical solutions using a higher order refined computational model with 12 degrees of freedom for the free vibration analysis of antisymmetric angle-ply plates(2008) Swaminathan, K.; Patil, S.S.Analytical formulations and solutions to the natural frequency analysis of simply supported antisymmetric angle-ply composite and sandwich plates hitherto not reported in the literature based on a higher order refined computational model with 12 degrees of freedom already reported in the literature are presented. The theoretical model presented herein incorporates laminate deformations which account for the effects of transverse shear deformation, transverse normal strain/stress and a nonlinear variation of in-plane displacements with respect to the thickness coordinate thus modelling the warping of transverse cross sections more accurately and eliminating the need for shear correction coefficients. In addition, another higher order computational model with five degrees of freedom already available in the literature is also considered for comparison. The equations of motion are obtained using Hamilton's principle. Solutions are obtained in closed-form using Navier's technique by solving the eigenvalue equation. Plates with varying slenderness ratios, number of layers, degrees of anisotropy, edge ratios and thickness of core to thickness of face sheet ratios are considered for analysis. Numerical results with real properties using above two computational models are presented and compared for the free vibration analysis of multilayer antisymmetric angle-ply composite and sandwich plates, which will serve as a benchmark for future investigations. © 2007 Elsevier Ltd. All rights reserved.Item Higher order refined computational models for the free vibration analysis of antisymmetric angle ply plates(2008) Swaminathan, K.; Patil, S.S.Analytical formulations using two higher order refined displacement models have been developed and solutions presented for the first time to the natural frequency analysis of antisymmetric angle-ply composite and sandwich plates. These computational models already reported in the literature are based on Taylor's series expansion of the displacements in the thickness coordinate and consider the realistic parabolic distribution of transverse shear strains through the laminate thickness. One of them, with 12 degrees of freedom, considers the effects of both transverse shear and normal strain/stress while the other with 9 degrees of freedom includes only the effect of transverse shear deformation. In addition to above, a few higher order models and the first order model developed by other investigators and available in the literature are also considered for the evaluation. A simply supported plate is considered throughout as a test problem. The equations of motion are obtained using Hamilton's principle. Solutions are obtained in closed form using Navier's technique by solving the eigenvalue equation. Plates with varying slenderness ratios, number of layers, fiber orientations, degrees of anisotropy, edge ratios and thickness of core to thickness of face sheet ratios are considered for the analysis. Accuracy of the theoretical formulations and the solution method is first ascertained by comparing the results with those already available in the literature. After establishing the accuracy of the solutions, extensive numerical results are presented for the free vibration analysis of multilayer antisymmetric angle-ply composite and sandwich plates using all the models, which will serve as a benchmark for future investigations. © SAGE Publications 2008.Item Stress analysis of Antisymmetric angle ply sandwich plates- analytical evaluation of refined higher order shear deformation theories(CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2011) Swaminathan, K.; Sangwai, G.R.In this paper two refined higher order computational models with 9 DOF and 12 DOF are considered. Analytical formulation developed and solutions obtained for the first time using these models for the stress analysis of antisymmetric angle ply sandwich plate. In addition, higher order model proposed by Reddy and the first order model already reported in the literature are also considered for the evaluation. A simply supported plate with SS-2 boundary conditions is considered for the analysis. The equations of equilibrium are obtained using Principle of Minimum Potential Energy (PMPE). Solutions are obtained in closed form using Navier’s technique. In-plane stresses are computed using the three dimensional constitutive relationships and the transverse stresses by post processing technique. Extensive numerical results using all the models are compared with 3D elasticity solutions already available in the literature to decide the accuracy of model. After establishing accuracy of the solution method benchmark results and comparison of solutions are presented for multilayer sandwich plates. It is observed that ESL models with twelve DOF are accurate, efficient and simple. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Effect of temperature on the performance of active constrained layer damping of skew sandwich plate with CNT reinforced composite core(Taylor and Francis Ltd., 2022) Kallannavar, V.; Kattimani, S.In this paper, the first attempt has been made to investigate the performance of the active constrained layer damping system in the thermal environment. For such investigation, a skew laminated composite sandwich plate with carbon nanotube-reinforced composite core is considered. The nonlinear strain-displacement relations are employed to generate the initial-stress stiffness matrix and the mechanical stiffness matrices using linear strain-displacement relations. The negative velocity feedback control-law is used to control the first few modes of the vibrating sandwich plate. Comprehensive investigation has been carried out to understand influence of geometric and material parameters on the damping performance of the system. © 2021 Taylor & Francis Group, LLC.Item Vibration and stability characteristics of functionally graded sandwich plates with/without porosity subjected to localized edge loadings(Taylor and Francis Ltd., 2023) Swaminathan, K.; Hirannaiah, S.; Rajanna, T.This article investigates the influence of porosity and localized edge loads on the vibration and buckling characteristics of functionally graded material (FGM) plates using the finite element (FE) method. The analysis is carried out by choosing a single-layer FGM and two different types of FGM sandwich plates in such a way that there is no material discontinuity along the thickness direction. The porosity imperfections are accounted for in this study as criteria of stiffness reduction and are incorporated using modified power law distribution. The vibration and buckling responses are studied by considering four types of localized edge loads on plates with different porosity distributions. The application of different types of localized edge loads on the plate leads to the development of nonuniform in-plane stresses. Hence, they are computed first by using a dynamic approach before obtaining the buckling loads. The accuracy of the FE formulation is first validated for FGM plates by comparing the natural frequencies and the critical buckling loads obtained in the present investigation with the solutions already available in the literature. After validating the accuracy, detailed parametric studies have been performed on plates with varying volume fraction exponent, porosity distribution, porosity index, side-to-thickness ratio, load width ratio, aspect ratio, and support condition, and the results are presented with appropriate conclusions. A probabilistic sensitivity analysis is carried out to identify the significant parameter affecting the buckling load and natural frequency of porous FGM plates subjected to localized edge loads, which considerably aids in the design of the FGM plates. © 2022 Taylor & Francis Group, LLC.Item Influence of porosity and nonuniform in-plane edge loads on vibration and buckling response of power law and sigmoid function based FG sandwich plates with geometrical discontinuities(Taylor and Francis Ltd., 2023) Swaminathan, K.; Hirannaiah, S.; Rajanna, T.Porosity defects can emerge during the manufacturing process of Functionally Graded Sandwich Plates (FGSPs). In practice, FGSPs have geometric discontinuities/cutouts and are exposed to Nonuniform In-plane Edge Loads (NIELs). The presence of porosity, cutout and NIELs causes a significant reduction in the stiffness of the plate affecting its vibration and buckling behavior. Therefore, in this paper vibration and buckling results obtained using the Finite Element (FE) method hitherto not reported in the literature are presented for porous FGSPs with cutouts and subjected to NIELs. Four types of porosity distribution models are explored, and the porosity imperfections are modeled as the criteria of stiffness reduction. Porosity-dependent material properties of FGSPs are evaluated using modified power law and sigmoid function. The current study incorporates two distinct kinds of sandwich configuration in such a way that there is no material mismatch along the thickness direction. The application of different cases of NIELs on the plate with cutouts leads to the development of nonuniform stresses. Hence a novel dynamic approach has been proposed to evaluate buckling loads by implementing two sets of boundary conditions. The first set of boundary conditions calculates pre-buckling stress, while second set calculates critical buckling loads. The generated results from the current FE formulation are compared with existing results in the literature to ensure accuracy. Finally, the effect of porosity distribution, NIELs, cutout ratio and its positions, support conditions, volume fraction exponents and geometric parameters on the vibration and buckling response are studied and discussed to arrive at appropriate conclusion. © 2022 Taylor & Francis Group, LLC.