Faculty Publications
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Item Free vibration analysis of single and multilayered sandwich FGM plates-assessment of higher order refined theories(2014) Swaminathan, K.; Naveenkumar, D.T.Analytical formulations and solutions for natural frequency analysis of functionally graded material (FGM) plates based on two higher-order refined shear deformation theories with 9 and 12 degrees-of-freedom are presented. The displacement model with 12 degrees-of-freedom considers the effect of both transverse shear and normal strain/stress while the other considers only the effect of transverse shear deformation. In addition another higher-order model and the firstorder model developed by other investigators and available in the literature are also presented for the evaluation purpose. For mathematical modeling purposes, the Poisson's ratio of the material is considered as constant whereas Young's modulus is assumed to vary through the thickness according to the power law function. The equations of motion are derived using Hamilton's principle. Solutions are obtained in closed-form using Navier's technique and solving the eigenvalue equation. The accuracy of the theoretical formulations and the solution method using the present two higher-order refined models is first established by comparing the results generated in the present investigation with the 3D elasticity solutions already reported in the literature. After establishing the accuracy of predictions, benchmark results for the natural frequencies using all the four models are presented for single layer FGM plate and multi layered FGM sandwich plate with varying edge ratios and side-to-thickness ratios. © (2014) Trans Tech Publications, Switzerland.Item Free Vibration Characteristics of Banana/Sisal Natural Fibers Reinforced Hybrid Polymer Composite Beam(Elsevier Ltd, 2016) RAJESH, M.; Jeyaraj, P.; Nagarajan, N.Natural fibers having more advantage compared to man-made fiber, such as glass, carbon, Kevlar fiber. But due to the hydrophilic nature of natural fiber gives poor adhesion between fiber-matrix. This will decrease the properties of polymer composite. In this study influence of surface pre-treatment with sodium hydroxide and hybridization effect of natural fiber are investigated on flexural test and free vibration behavior. In this work sisal and banana natural fibers are used in short and random orientations to prepare the polymer composites using compression moulding method. From the experimentation, it is found that chemical treatment improves the mechanical and free vibration properties of polymer composites due to the enhancement of interfacial bond between fiber and matrix as the result of chemical treatment. © 2016 The Authors.Item Buckling and Free Vibration Characteristics of a Uniformly Heated Isotropic Cylindrical Panel(Elsevier Ltd, 2016) Bhagat, V.; Jeyaraj, P.; Murigendrappa, S.M.In this paper buckling and free vibration characteristics of an isotropic cylindrical panel subjected to uniform temperature rise has been investigated using finite element method. The procedure involves the determination of critical buckling temperature, which is followed by modal analysis considering pre-stress due to the thermal field in the cylindrical panel. Detailed studies are carried out to analyze the influence of curvature ratio, thickness ratio and aspect ratio on the critical buckling temperature and free vibration behavior of an isotropic cylindrical panel. It has been found that as the curvature ratio and the thickness ratio increases the thermal buckling strength of the cylindrical panel decreases. It has also been found that free vibration frequencies reduce with an increase in temperature and the reduction is more significant for the lowest frequency mode. It is observed that free vibration mode shapes at ambient temperature changes with an increase in temperature. © 2016 The Authors.Item Buckling and Free Vibration Behavior of a Temperature Dependent FG-CNTRC Cylindrical Panel under Thermal Load(Elsevier Ltd, 2018) Bhagat, V.; Jeyaraj, P.; Murigendrappa, S.M.Present study deals with the buckling and free vibration behavior of functionally graded carbon-nanotubes reinforced composite (FG-CNTRC) cylindrical panel exposed to uniform thermal load. Stresses setup due to thermal load and temperature dependent properties influences the buckling and free vibration behavior of the heated structures. Approach employed in the present study consists of static analysis to compute thermal stresses, eigen-value buckling analysis to compute critical buckling temperature and finally modal analysis, taking thermal stresses into account. Influence of different CNTs grading pattern, CNTs volume fraction, geometric parameters, boundary constraints and temperature dependent properties on the buckling strength are investigated. It is observed that hybrid CNTs distribution pattern gives comparatively higher buckling strength and free vibration frequencies. Investigation on free vibration characteristics of the FG-CNTRC panel at elevated temperature signifies that the decline in free vibration frequencies is very drastic at a temperature close to buckling temperature along with temperature dependent properties. c 2017 Elsevier Ltd. All rights reserved. © 2018 Elsevier Ltd.Item Mechanical behavior of 3D printed syntactic foam composites(Elsevier Ltd, 2020) Bharath, H.S.; Sawardekar, A.; Waddar, S.; Jeyaraj, J.; Doddamani, M.A three-dimensional printed (3DP), polymer based syntactic foams are developed using hollow glass micro balloons (GMB) dispersed in high density polyethylene (HDPE). This work presents the buckling and vibration response of 3D printed foams subjected to axial compression. The buckling load is estimated using Modified Budiansky Criteria (MBC) and Double Tangent Method (DTM) through the load–deflection plots. The first three natural frequencies and their mode shapes are computed as a function of axial compressive load. It is noted that the natural frequency reduces with an increase in axial compressive load. It is also observed that with an increase in GMB %, the natural frequencies and critical buckling load increases. In mode-1, the natural frequency decreases in pre-buckling regimes and increases exponentially in post-critical loading conditions. Analytical solutions obtained from the Euler-Bernoulli-beam theory are compared with experimental results. It is noted that the fundamental frequency approaches zero when the axial load is equal to the critical load. The critical buckling load is estimated through the vibration correlation technique and compared with the results obtained using DTM and MBC methods. The property map is plotted for buckling load against the density of various composites. © 2020 Elsevier LtdItem Effect of lamination schemes on natural frequency and modal damping of fiber reinforced laminated beam using Ritz method(EDP Sciences, 2021) Somi Naidu, S.N.; Jeyaraj, J.; Mailan Chinnapandi, L.B.; Reddi, C.V.S.N.The current study focussed on analysing natural frequency and damping of laminated composite beams (LCBs) by varying fiber angle, aspect ratio, material property and boundary conditions. Ritz method with displacement field based on the shear and normal deformable theory is used and the modal damping is calculated using modal strain energy method. Effects of symmetric angle-ply and cross-ply, anti symmetric cross-ply, balanced and quasi-isotropic lay up schemes on modal damping are presented for the first time. Results revealed that influence of lay-up scheme on natural frequencies is significant for the thin beams while the modal damping of the thin beams are not sensitive to lay-up scheme. However, the lay-up scheme influences the damping significantly for the thick beams. Similarly, high strength fiber reinforced LCBs have higher natural frequency while low strength fiber reinforced LCBs have higher damping due to the better fiber-matrix interaction. © S.N. Balireddy et al., Published by EDP Sciences, 2021.Item Response of fly ash-reinforced functionally graded rubber composites subjected to mechanical loading(2012) Doddamani, M.R.; Kulkarni, S.M.A novel approach to estimate the Young's modulus of a functionally graded rubber composite (FGRC) from the damping ratio is demonstrated with the examples of unreinforced and fly ash-reinforced materials. FGRC coupons were prepared using the conventional casting technique. The occurrence of gradation in the specimens was attributed to the variable density of particles present in the fly ash, settling at different depths. The technique of free vibrations was used for experimentation. The damping response of the FGRC specimens was studied. The results obtained from the experiments showed that, with growing filler weight fraction, the Young's modulus of the composite increased. The empirical model developed to predict the magnitude of the modulus turned out to be in good agreement with experimental data. © 2012 Springer Science+Business Media, Inc.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 Tensile, impact, and vibration properties of coconut sheath/sisal hybrid composites: Effect of stacking sequence(SAGE Publications Ltd, 2014) Krishnasamy, K.S.; Siva, I.; Nagarajan, N.; Jeyaraj, P.; Winowlin Jappes, J.W.This work addresses the tensile, impact, and free vibration properties of sisal/coconut sheath fiber hybrid-reinforced unsaturated polyester composites. The hybrid composites are fabricated using a compression molding technique with varying stacking sequences under as-received or chemically treated conditions. The chemical treatments (alkali and tri-chloro vinyl silane) have shown better performance than untreated composites. Furthermore, the silane-treated composite shows enhanced static mechanical and free vibration properties for all stacking sequences relative to the other two cases. From the experimental results, the silane-treated coconut sheath/sisal/coconut sheath hybrid stack is found to be an optimum stacking sequence for better properties. Further, an encouraging damping factor value is also observed for the optimum stacking sequence. The failure mechanism of interfacial de-bonding between the fibers and the matrix is analyzed with the aid of scanning electron microscopy. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.Item Free vibration analysis of axisymmetric laminated composite circular and annular plates using Chebyshev collocation(SpringerOpen, 2015) Powmya, A.; Narasimhan, M.C.Solutions, based on principle of collocating the equations of motion at Chebyshev zeroes, are presented for the free vibration analysis of laminated, polar orthotropic, circular and annular plates. The analysis is restricted to axisymmetric free vibration of the plates and employs first-order shear deformation theory for the displacement field, in terms of midplane displacements, u, ? and w. The eigenvalue problem is defined in terms of three equations of motion in terms of the radial co-ordinate r, the radial variation of the displacements being represented in polynomial series, with appropriate boundary conditions. Numerical results are presented to show the validity and accuracy of the proposed method. Results of parametric studies for laminated polar orthotropic circular and annular plates with different boundary conditions, orthotropic ratios, lamination sequences, number of layers and shear deformation are also presented. © 2015, The Author(s).