Faculty Publications
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Item Static analysis of functionally graded beams using higher order shear deformation theory(2008) Kadoli, R.; Akhtar, K.; Ganesan, N.Displacement field based on higher order shear deformation theory is implemented to study the static behavior of functionally graded metal-ceramic (FGM) beams under ambient temperature. FGM beams with variation of volume fraction of metal or ceramic based on power law exponent are considered. Using the principle of stationary potential energy, the finite element form of static equilibrium equation for FGM beam is presented. Two stiffness matrices are thus derived so that one among them will reflect the influence of rotation of the normal and the other shear rotation. Numerical results on the transverse deflection, axial and shear stresses in a moderately thick FGM beam under uniform distributed load for clamped-clamped and simply supported boundary conditions are discussed in depth. The effect of power law exponent for various combination of metal-ceramic FGM beam on the deflection and stresses are also commented. The studies reveal that, depending on whether the loading is on the ceramic rich face or metal rich face of the beam, the static deflection and the static stresses in the beam do not remain the same. © 2007 Elsevier Inc. All rights reserved.Item Effect of temperature and moisture on free vibration characteristics of skew laminated hybrid composite and sandwich plates(Elsevier Ltd, 2020) Kallannavar, V.; Kumaran, B.; Kattimani, S.C.This paper is concerned with the effect of variation in temperature and moisture concentration on free vibration response of skew laminated hybrid composite and sandwich plates. The coupled thermo-elastic and hygro-elastic finite element model is formulated using the first-order shear deformation theory (FSDT). Uniform temperature and moisture concentration rise is considered for the analysis. Soft-core viscoelastic materials are considered for the sandwich plates and are modeled using the complex modulus approach. Linear strain-displacement relations are used to develop a mechanical stiffness matrix, and the initial stress stiffness matrix is generated using non-linear strain-displacement relations to represent the non-mechanical stiffness matrix. Numerical examples for the generated finite element model are presented and discussed comprehensively to understand the effect of temperature, moisture concentration, skew angle, length to width ratio, length to thickness ratio, and boundary conditions on the vibration response of the laminated hybrid composite and sandwich plates. Further investigation is devoted to studying the influence of temperature and moisture concentration-dependent material properties, stacking sequence, core to face sheet thickness ratio, and fiber orientation on vibration behavioral response of sandwich and hybrid composite plates. © 2020 Elsevier LtdItem Free vibration analysis and selection of composite for high strength and stiffness using multi-attribute decision making(Walter de Gruyter GmbH, 2021) Allien, V.; Kumar, H.; Desai, V.This paper describes the optimal selection of chopped strand mat glass-fiber-reinforced unsaturated polyester resin (CGRP) polymer matrix composite (PMC) by considering the strength and stiffness of various composite samples. The two-, four-, six-, eight- and ten-layered CGRP-PMC samples were prepared by using a hand-layup method. Then, the natural frequency and damping ratio of the CGRP-PMC samples were determined through experimental free vibration analysis using DEWESoft software. The density, tensile strength, flexural strength, impact strength, absorbed energy, inter-laminar shear strength, and fracture toughness results of the CGRP-PMC samples were considered as attributes for the selection of the optimal composite using multi-attribute decision making (MADM) techniques. The six-layered CGRP-PMC material was selected as the optimal PMC based on the results of MADM techniques. © 2021 Walter de Gruyter GmbH, Berlin/Boston, Germany 2021.Item Neural network-based prediction model to investigate the influence of temperature and moisture on vibration characteristics of skew laminated composite sandwich plates(MDPI AG, 2021) Kallannavar, V.; Kattimani, S.; Soudagar, M.E.M.; Abbas, M.A.; Alshahrani, S.; Imran, M.The present study deals with the development of a prediction model to investigate the impact of temperature and moisture on the vibration response of a skew laminated composite sandwich (LCS) plate using the artificial neural network (ANN) technique. Firstly, a finite element model is generated to incorporate the hygro-elastic and thermo-elastic characteristics of the LCS plate using first-order shear deformation theory (FSDT). Graphite-epoxy composite laminates are used as the face sheets, and DYAD606 viscoelastic material is used as the core material. Non-linear strain-displacement relations are used to generate the initial stiffness matrix in order to represent the stiffness generated from the uniformly varying temperature and moisture concentrations. The mechanical stiffness matrix is derived using linear strain-displacement associations. Then the results obtained from the numerical model are used to train the ANN. About 11,520 data points were collected from the numerical analysis and were used to train the network using the Levenberg– Marquardt algorithm. The developed ANN model is used to study the influence of various process parameters on the frequency response of the system, and the outcomes are compared with the results obtained from the numerical model. Several numerical examples are presented and conferred to comprehend the influence of temperature and moisture on the LCS plates. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.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 Influence of Temperature and Moisture on Free Vibration Behavior of Skew Laminated Composite Sandwich Panels with CNTRC Core(World Scientific, 2022) Kallannavar, V.; Kattimani, S.; Ramesh, H.This paper presents the influence of temperature and moisture on the free vibration characteristics of skew laminated composite sandwich (SLCS) panels. The face sheets of the panels are made of graphite-epoxy composite, while the core consists of carbon nanotube-reinforced composite. The coupled hygro-elastic and thermo-elastic relations for the SLCS shells/panels are formulated using first-order shear deformation theory. The nonmechanical stiffness matrices are represented by the initial stress stiffness matrix developed using nonlinear strain-displacement relations. The temperature and moisture-dependent material properties are considered to analyze the laminated composite sandwich spherical, hyperbolic, ellipsoid, cylindrical Shells, and flat plates. Several numerical examples are comprehensively studied to establish the influence of temperature, moisture, the volume fraction of carbon nanotubes in the core material, functional gradation types, skew angle, and edge constraints on the vibration responses of SLCS shells. Further exploration is devoted to studying the combined effect of moisture, temperature, and the geometrical parameters such as length to width ratio, length to thickness ratio, radius-to-length ratio, and the core thickness to face sheet thickness ratios on the natural frequency of the skew laminated composite sandwich panels. © 2022 World Scientific Publishing Company.Item Static, free vibrational and buckling analysis of laminated composite beams using isogeometric collocation method(Elsevier Ltd, 2022) Pavan, G.S.; Muppidi, H.; Dixit, J.Isogeometric collocation (IGA-C) method is a computational approach to solve boundary value problems. In this method (IGA-C), the differential equations are solved in strong form instead of the weak form approach adopted by Galerkin based formulations. IGA-C method is computationally efficient in comparison to conventional finite element method and Galerkin-Isogeometric approaches. IGA-C method does not involve the process of assembling global stiffness matrix from element stiffness matrix. Another advantage of IGA-C is that it requires a single integration point per element irrespective of the order of Non-Uniform Rational B-Spline functions (NURBS) adopted. Isogeometric collocation has also been demonstrated as a stable, efficient and accurate higher order computational method for explicit problems. For a wider adoption of isogeometric collocation method, beam/plate/shell finite elements within the framework of IGA-C method need to be formulated. Owing to the extensive adoption of laminated composites in structural components, development of beam finite elements for laminated composite beams based on isogeometric collocation method will prove useful during analysis of composite structures. IGA-C method is proposed in this study for the static bending, free vibration and buckling analysis of laminated composite beams. Classical laminated plate theory (CLPT), first order shear deformation theory (FSDT) and higher order shear deformation theory (HSDT) are considered for all the three analyses. The computational approach proposed for laminated beam based on HSDT contains two Degrees of Freedom (DOF) per node. Computational approach for analysing laminated composite beams based on each of these kinematic theories and using IGA-C method is presented. Accuracy of the proposed computational approaches is checked by solving different numerical examples. Values of normalized transverse displacement, normalized stresses, normalized natural frequencies and normalized critical buckling loads are compared with results from the literature and are found to be accurate. © 2022 Elsevier Masson SASItem Effect of temperature and porosity on free vibration characteristics of a doubly-curved skew laminated sandwich composite structures with 3D printed PLA core(Elsevier Ltd, 2023) Kallannavar, V.; Kattimani, S.This paper deals with the investigation of the influence of temperature and porosity on the vibration response of the doubly-curved skew laminated sandwich composite (DSLSC) shells. The temperature-reliant properties of the graphite–epoxy face sheet and the 3D printed polylactic acid (PLA) core are considered for the numerical analysis. The coupled thermo-elastic finite element (FE) model is developed using the first-order shear deformation theory (FSDT) to study the influence of uniform temperature rise on the modal behavior of the DSLSC shells. The stiffness generated due to thermal exposure is accounted to introduce the initial stress stiffness matrix. Further, the initial stress stiffness matrix is developed using nonlinear strain–displacement relations, while the mechanical stiffness matrices are characterized using linear strain–displacement relations. A comprehensive parametric study has been performed to appreciate the effect of temperature, geometric restraints, and material constraints of a laminated composite sandwich spherical, hyperbolic, ellipsoidal, cylindrical shells, and flat plates. Series of experiments are performed to understand the influence of temperature on the natural frequency of glass–epoxy laminated composite sandwich plates with 3D printed PLA core. Further exploration is dedicated to comprehending the experimental challenges involved in studying the vibration performance of sandwich structures with 3D printed PLA core in the thermal environment. © 2022 Elsevier LtdItem Nonlinear thermo-elastic stability of variable stiffness curvilinear fibres based layered composite beams by shear deformable trigonometric beam model coupled with modified constitutive equations(Elsevier Ltd, 2023) Manickam, G.; Haboussi, M.; D'Ottavio, M.; Kulkarni, V.; Chettiar, A.; Gunasekaran, V.Nonlinear thermo-elastic buckling characteristics of composite variable stiffness beam with layers making use of curvilinear fibres under thermal environment is attempted here. The model is based on a shear deformable theory introducing trigonometric function, and considering von Kármán's assumptions based geometrical nonlinear effect. The beam constitutive equation is modified according to the stress-free situation in the width direction of beam-Poisson's effect in the formulation for predicting the behaviour of general lay-up composite beams. By the principle of minimum total potential energy, the governing equations in terms of incremental stiffness matrices are formed introducing general beam finite element. The global equilibrium equations formulated are solved for envisaging the post-buckling path through eigenvalue analysis iteratively, thus establishing the relationship of thermal temperature against moderate amplitude level of beam deflection. A systematic parametric analysis considering different lamina properties such as curvilinear fibre path angles and including lay-up sequences, thermal expansion coefficient, mixed laminate combining straight and curvilinear fibres-based layers is carried out on thermo-structural stability of curvilinear fibre-based beams. Also, the influence of geometric factors, flexible beam end support, and variation in thermal profile, etc. over the stability behaviour of beam is examined. © 2022Item Free vibration analysis of a skew sandwich plate with bamboo biocomposite and polylactic acid core under temperature and moisture conditions(SAGE Publications Inc., 2023) Gawande, A.S.; Kattimani, S.; Murigendrappa, S.M.; Nguyen, T.; kamyab, H.; Althamer, S.This article investigates the impact of moisture and temperature on vibration characteristics of bio-composite skew-laminated composite sandwich (SLCS) plates. The bio-composite SLCS plates with bamboo face sheets and polylactic acid (PLA) cores are biodegradable, radiolucent, lightweight, high strength, and withstand vibrations. The coupled thermo-elastic and hygro-elastic finite element (FE) model of the SLCS plate is derived using the higher-order shear deformation theory (HSDT). An initial stress stiffness matrix is developed using the nonlinear strain-displacement relations to incorporate the effect of temperature and moisture in FE modeling. Temperature and moisture-dependent material properties of bamboo fiber-reinforced biocomposite (BFB) and PLA core are employed for the analysis. A comprehensive investigation has been carried out to study the impact of moisture and temperature situations with different geometrical parameters and various skew angles on the frequency of the SLCS plate. The results indicate that the biocomposite sandwich material has excellent potential for structural applications under different environmental conditions in various applications like food processing, and biomedical applications, including MRI and CT scan beds. © The Author(s) 2023.