Faculty Publications
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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 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 Buckling and vibration behavior of a non-uniformly heated isotropic cylindrical panel(Techno-Press, 2016) Bhagat, V.S.; Jeyaraj, P.; Murigendrappa, S.M.This study attempts to address the buckling and free vibration characteristics of an isotropic cylindrical panel subjected to non-uniform temperature rise using numerical approach. Finite element analysis has been used in the present study. The approach involves three parts, in the first part non-uniform temperature field is obtained using heat transfer analysis, in the second part, the stress field is computed under the thermal load using static condition and, the last part, the buckling and pre-stressed modal analysis are carried out to compute critical buckling temperature as well as natural frequencies and associated mode shapes. In the present study, the effect of non-uniform temperature field, heat sink temperatures and in-plane boundary constraints are considered. The relation between buckling temperature under uniform and non-uniform temperature fields has been established. Results revealed that decrease (Case (ii)) type temperature variation field influences the fundamental buckling mode shape significantly. Further, it is observed that natural frequencies under free vibration state, decreases as temperature increases. However, the reduction is significantly higher for the lowest natural frequency. It is also found that, with an increase in temperature, nodal and anti-nodal positions of free vibration mode shapes is shifting towards the location where the intensity of the heat source is high and structural stiffness is low. © © 2016 Techno-Press, Ltd.Item Buckling and free vibration of nonuniformly heated functionally graded carbon nanotube reinforced polymer composite plate(World Scientific Publishing Co. Pte Ltd wspc@wspc.com.sg, 2017) George, N.; Jeyaraj, P.; Murigendrappa, S.M.Buckling and free vibration behavior of functionally graded carbon nanotube reinforced polymer composite plate subjected to nonuniform temperature fields have been investigated using finite element approach. The effective material constants of the plate are obtained using the extended rule of mixture along with efficiency parameters of the carbon nanotube (to include geometry-dependent material properties). Influence of boundary conditions, aspect ratio, functional grading of the carbon nanotube, nonuniform thermal loading on thermal buckling and free vibration behavior of the heated plate are analyzed. It is observed that temperature fields and functional grading are influenced on the critical buckling temperature of the plates. Further, nature of functional grading showed significant change in buckling mode shapes irrespective of the boundary conditions. The first few natural frequencies of the plate under thermal load decreases as the temperature increases and they are influenced significantly by the nature of temperature field. Variations in free vibration mode shapes of the square plates found with not significant change as temperature increases. However, free vibration modes of the rectangular plates are sensitive to the nature of temperature field whenever there is a free edge associated with the boundary condition. Influence of functional grading on the free vibration mode shapes is not significant in contrast with the free vibration natural frequencies. The magnitude of free vibration natural frequencies of functional grade-X type carbon nanotube reinforcement showed higher in comparison with other two types of reinforcements considered here. © 2017 World Scientific Publishing Company.Item Influence of axial compressive loads on buckling and free vibration response of surface-modified fly ash cenosphere/epoxy syntactic foams(SAGE Publications Ltd info@sagepub.co.uk, 2018) Waddar, S.; Jeyaraj, P.; Doddamani, M.This work deals with experimental buckling and free vibration behavior of silane-treated cenosphere/epoxy syntactic foams subjected to axial compression. Critical buckling loads are computed from compressive load–deflection plots deduced using universal testing machine. Further, compressive loads are applied in the fixed intervals until critical loading point on different set of samples having similar filler loadings to estimate natural frequency associated with the first three transverse bending modes. Increasing filler content increases critical buckling load and natural frequency of syntactic foam composites. Increasing axial compressive load reduce structural stiffness of all the samples under investigation. Syntactic foams registered higher stiffness compared to neat epoxy for all the test loads. Similar observations are noted in case of untreated cenosphere/epoxy foam composites. Silane-modified cenosphere embedded in epoxy matrix registered superior performance (rise in critical buckling load and natural frequencies to the tune of 23.75% and 11.46%, respectively) as compared to untreated ones. Experimental results are compared with the analytical solutions that are derived based on Euler–Bernoulli hypothesis and results are found to be in good agreement. Finally, property map of buckling load as a function of density is presented by extracting values from the available literature. © The Author(s) 2018.Item Buckling and free vibration behavior of cenosphere/epoxy syntactic foams under axial compressive loading(ASTM International, 2018) Waddar, S.; Jeyaraj, P.; Doddamani, M.; Gupta, N.The buckling and free vibration behavior of cenosphere/epoxy syntactic foams under axial compressive loading are investigated experimentally in this work. The buckling load is obtained from the load-deflection curve based on the Double Tangent Method (DTM) and Modified Budiansky Criteria (MBC). Furthermore, the influence of an axial compression load on the natural frequencies associated with the first three transverse bending modes is analyzed. Finally, the buckling loads predicted using DTM and MBC are compared to the buckling load calculated based on the vibration correlation technique. It is observed that the buckling loads predicted through the three different methods are in close agreement. The experimental results revealed that the buckling load and natural frequency of the syntactic foams increase with the cenosphere volume fraction. It is observed that the natural frequencies reduce with increases in the axial compression load for all the modes. However, a rapid increase in the fundamental frequency is observed when the compressive load is near and beyond the critical buckling load. © © 2018 by ASTM International.Item Buckling and vibration behaviour of syntactic foam core sandwich beam with natural fiber composite facings under axial compressive loads(Elsevier Ltd, 2019) Waddar, S.; Jeyaraj, P.; Doddamani, M.; Barbero, E.An experimental study of buckling and dynamic response of cenosphere reinforced epoxy composite (syntactic foam) core sandwich beam with sisal fabric/epoxy composite facings under compressive load is presented. Influence of cenosphere loading and surface modification on critical buckling load and natural frequencies of the sandwich beam under compressive load is presented. The critical buckling load is obtained from the experimental load-deflection data while natural frequencies are obtained by performing experimental modal analysis. Results reveal that natural frequencies and critical buckling load increase significantly with fly ash cenosphere content. It is also observed that surface modified cenospheres enhance natural frequencies and critical buckling load of the sandwich beam under compressive load. Vibration frequencies reduce with increase in compressive load. Fundamental frequency increases exponentially in post-buckling regime. Experimentally obtained load-deflection curve and natural frequencies are compared with finite element analysis wherein results are found to be in good agreement. © 2019 Elsevier LtdItem Buckling and dynamic responses of 3D printed nanocomposites and their graded variants(Elsevier Ltd, 2023) Kumar, S.; Ramesh, M.R.; Jeyaraj, P.; Doddamani, M.The experimental and numerical investigations are carried out for buckling and vibration of 3D printed functionalized MWCNTs/HDPE based nanocomposite (NC) and their functionally graded nanocomposite (FGNC) variants. Pcr(critical buckling load) is computed through MBC (modified budiansky criteria) and DTM (double tangent method) techniques. It is observed that Pcr of the 3D printed NCs and FGNCs increases with the functionalized MWCNTs content. The Pcr values for the NCs (H0.5-H5) computed using DTM and MBC increased in the range of 16–79%, while for FGNC-1 (H0.5-H1-H3) and FGNC-2 (H1-H3-H5), the Pcr increased from 54 to 91% compared to HDPE. Further, it is observed that the natural frequency of the NCs and FGNCs increases with the functionalized MWCNTs loading while decreases with rise in compression. The natural frequency of the NCs (H0.5-H5) and FGNCs increased up to 41% than HDPE. The highest Pcr and the natural frequency is noted for H5 and FGNC-2 prints. The experimental and numerical results showed good agreement. © 2023 Elsevier Ltd