Faculty Publications
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Publications by NITK Faculty
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Item Synergy of fiber length and content on free vibration and damping behavior of natural fiber reinforced polyester composite beams(Elsevier Ltd, 2014) Krishnasamy, K.; Siva, I.; Jeyaraj, P.; Winowlin Jappes, J.T.; Amico, S.C.; Nagarajan, N.This work addresses the results of experimental investigation carried out on free vibration characteristics of short sisal fiber (SFPC) and short banana fiber (BFPC) polyester composites. Influence of fiber length and weight percentage on mechanical properties and free vibration characteristics are analyzed. Composite beam specimen is fabricated with random fiber orientations at17. MPa compression using compression molding machine. Natural frequencies and associated modal damping values of the composite laminates were obtained by carrying out the experimental modal analysis. It is found that an increase in fiber content increases the mechanical and damping properties. For SFPC, 3. mm fiber length and 50. wt% fiber content yielded better properties, whereas for BFPC, 4. mm fiber length and 50. wt% fiber content was the best combination. Scanning electron microscopy was performed to study the interfacial mechanism. © 2013 Elsevier Ltd.Item Experimental investigation of 3D-printed polymer-based MR sandwich beam under discretized magnetic field(Springer Verlag service@springer.de, 2018) Rajpal, R.; Lijesh, K.P.; Gangadharan, K.V.Smart materials are being employed in dynamic systems to tune the stiffness and damping of the structure by using external stimuli. Magnetorheological elastomers (MREs) are considered to be as one of the smart materials because of their characteristics of altering the dynamic properties under the external magnetic field. So far, MRE sandwich beams have been developed by embedding them between two parent structures. In the present work, a novel technique of embedding MR materials is presented to create complex sandwich structures. This technique will replace the conventional embedding technique which uses adhesives to bind the MR materials with the parent structure. The vibration characteristics of the developed sandwich beams are estimated by conducting harmonic analysis to a predefined band of frequency range under the different directions of magnetic field. Sinusoidal signals of desired frequency and amplitude were proffered using NI educational laboratory virtual instrumentation suite to an amplified piezoactuator for exciting the MR sandwich beam. A non-contact-type laser displacement sensor is used in this study to avoid the additional mass of the sensor on the beam. The results indicate that the smart materials can be efficiently embedded with the sandwich beam without using the adhesives. It is also found that by changing the direction of magnetic field, the range of the variation in stiffness of MR sandwich beam can be increased to enhance the isolation effect at fundamental natural frequency. © 2018, The Brazilian Society of Mechanical Sciences and Engineering.Item Nonuniform Heat Effects on Buckling of Laminated Composite Beam: Experimental Investigations(World Scientific Publishing Co. Pte Ltd wspc@wspc.com.sg, 2018) George, N.; Jeyaraj, P.The influence of nonuniform heating on the critical buckling temperature of laminated glass-epoxy composite beam has been investigated experimentally with the help of a novel experimental setup. The beam is numerically investigated using nonlinear finite element analysis. An initial geometric imperfection is introduced to the modeled geometry in numerical technique to have an experimental-numerical comparison of temperature-deflection plot. The results indicate that the critical buckling temperature of a uniformly heated beam has a significant difference in comparison to the nonuniformly heated beam and it depends on the heating source location and the resulting temperature distribution along the length direction of the beam. © 2018 World Scientific Publishing Company.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 Semi-active vibration control of SiC-reinforced Al6082 metal matrix composite sandwich beam with magnetorheological fluid core(SAGE Publications Ltd info@sagepub.co.uk, 2020) Allien, J.V.; Kumar, H.; Desai, V.Dynamic characterization of silicon carbide particles reinforced Al6082 alloy metal matrix composite sandwich beam with magnetorheological fluid core is experimentally investigated. The study is focused on determining the effect of magnetorheological fluid core on the dynamic behavior of the sandwich structure. The magnetorheological fluid core is enclosed between the top and bottom metal matrix composite beams. The metal matrix composite beams are cast with silicon carbide particles in Al6082 alloy varying from 0 to 20 wt%. The magnetorheological fluid is prepared in-house and contains 30 vol.% carbonyl iron powder and 70 vol.% silicone oil. The free vibration test is conducted to determine the natural frequencies and damping ratio. It is found that the natural frequencies and damping ratio of the sandwich beams increased with an increase in the applied magnetic flux density. The experimental forced dynamic response of sandwich beams is carried out using sine sweep excitation. Vibration amplitude suppression capabilities of the sandwich beams subjected to varying magnetic flux densities are determined. The experimental forced vibration results reveal that metal matrix composite–magnetorheological fluid core sandwich beams have excellent vibration amplitude suppression capabilities. © IMechE 2019.Item Semi-active vibration control of MRF core PMC cantilever sandwich beams: Experimental study(SAGE Publications Ltd info@sagepub.co.uk, 2020) Allien, J.V.; Kumar, H.; Desai, V.The semi-active vibration control of sandwich beams made of chopped strand mat glass fiber reinforced polyester resin polymer matrix composite (PMC) and magnetorheological fluid (MRF) core were experimentally investigated in this study. Two-, four- and six-layered glass fiber reinforced polyester resin polymer matrix composites were prepared using the hand-layup technique. The magnetorheological fluid was prepared in-house with 30% volume of carbonyl iron powder and 70% volume of silicone oil. Nine cantilever sandwich beams of varying thicknesses of the top and bottom layers glass fiber reinforced polyester resin polymer matrix composite beams and middle magnetorheological fluid core were prepared. The magnetorheological fluid core was activated with a non-homogeneous magnetic field using permanent magnets. The first three modes, natural frequencies and damping ratios of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams were determined through free vibration analysis using DEWESoft modal analysis software. The amplitude frequency response of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams through forced vibration analysis was determined using LabVIEW. The effect of various parameters such as magnetic flux density, thickness of glass fiber reinforced polyester resin polymer matrix composite layers and magnetorheological fluid core layer on the natural frequencies, damping ratio and vibration amplitude suppressions of the glass fiber reinforced polyester resin polymer matrix composite-magnetorheological fluid core sandwich beams was investigated. Based on the results obtained, 2 mm thickness top and bottom layers glass fiber reinforced polyester resin polymer matrix composite and 5 mm thickness magnetorheological fluid core sample have achieved a high shift in increased natural frequency, damping ratio and vibration amplitude suppression under the influence of magnetic flux density. © IMechE 2020.Item Effect of thermal loading on syntactic foam sandwich composite(John Wiley and Sons Inc. cs-journals@wiley.com, 2020) Waddar, S.; Jeyaraj, J.; Doddamani, M.An experimental investigation carried out on the deflection behavior of sandwich composites with a fly ash cenosphere/epoxy syntactic foam core and plain-woven sisal fiber fabric/epoxy skin subjected to nonuniform heating is presented. The influence of cenosphere volume fraction in the syntactic foam core, three different heating cases (increase-decrease, decrease, and decrease-increase), and cenospheres’ surface treatment effect is analyzed. The temperature deflection is acquired with the help of a LabVIEW program. The critical buckling and snap-initiation temperatures are found from the temperature-deflection plots. It is observed that the sandwich beam undergoes snap-through buckling behavior due to viscoelastic forces associated with the syntactic foam core. The critical buckling temperature increases with the filler content, and the surface treatment enhances the buckling behavior marginally. Results also demonstrate that the sandwiching of the syntactic foam core between the natural fiber skin enhances critical buckling temperatures compared to the syntactic foam core. © 2020 Society of Plastics EngineersItem Studies on free and forced vibration of functionally graded back plate with brake insulator of a disc brake system(Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2020) Patil, R.; Joladarashi, S.; Kadoli, R.The back plate with brake insulator of a disc brake system used in automobile is a sandwich structure. Mitigating brake squeal associated with the operation of the disc brake has been a focus of many automobile researchers. As on today’s practice, steel–acrylic–steel is used for back plate–brake insulator assembly. The present study focuses on proposing Al - Al 2O 3 functionally graded metal ceramic composite material (FGM) for the back plate attached with conventional Steel–Acrylic brake insulator. Accordingly, a comparison study is presented in terms of the free and forced vibration characteristics of different material combinations for back plate–brake insulator sandwich beams such as steel–acrylic–steel, FGM–acrylic–steel, FGM–acrylic–aluminium and steel–acrylic–aluminium. The associated governing equations for sandwich beam which are well established in the literature are presented, and they are solved for simply supported conditions using trigonometric displacement functions. The real and imaginary parts of the various parameters come into the picture because of complex shear modulus of viscoelastic core. The comparison study among the combinations reveals that the natural frequency, loss factor and with regard to dynamic loading the imaginary part of transverse displacement, axial displacement, stress and strain of FGM–acrylic–steel are higher. As a result, FGM–acrylic–steel is suitable combination for back plate and brake insulator assembly which enhances the damping capacity of overall disc brake system and also helps in reducing brake squeal problem associated with operation of disc brake system. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Item Numerical analysis of polymer composites for actuation(International Information and Engineering Technology Association, 2020) Hiremath, S.; Sangappa, V.; Rajole, S.; Kulkarni, S.M.The design of a polymer composite actuator is essential for micro and nano applications. Thus, the composite material may deform or deflects as specific stimuli are applied, such as heat, electrical, light source, etc. The deformation of the composite material is caused by the type of stimulus applied. Hence, while it is heated, the expansion takes place quickly, and the heating is shut down, the material shrinks very slowly. In the present investigation, this phenomenon is mainly studied in the actuation of composite beams. Numerical analysis of carbon black filled polymer composite beam expansion, and contraction is being analyzed in this research. The structure of the beam has been created, and the composite properties are incorporated into the beam, and the uniform heat source is applied on to the surface of the beam. The heating and cooling of the composite material predict the increase and decrease in the temperature of the beam. The numerical analysis of the temperature-dependent expansion and contraction of the composite beam has been carried out successfully. An increase in temperature is observed to signify the slight expansion in the composite beam, whereas the contraction of the composite beam takes a longer time to reach room temperature. Also, the increase in the content of the filler leads to a decrease in the expansion of the composite beam. The numerical simulation of the polymer composite thus provides a solid platform for the experimental study of thermal actuators. © 2020 Lavoisier. All rights reserved.Item Dynamic behavior of sandwich beams with different compositions of magnetorheological fluid core(Taylor and Francis Ltd., 2021) Acharya, S.; Allien, V.J.; Puneet, P.; Kumar, H.Magnetorheological fluid (MRF) sandwich beams belong to a class of adaptive beams that consists of MRF sandwiched between two or more face layers and have a great prospective for use in semi-active control of beam vibrations due to their superior vibration suppression capabilities. The composition of MRF has a strong influence on the MRF properties and hence affects the vibration characteristics of the beam. In this work, six MRF samples (MRFs) composed of combination of two particle sizes and three weight fractions of carbonyl iron powder (CIP) were prepared and their viscoelastic properties were measured. The MRFs were used to fabricate different MRF core sandwich beams. Additionally, a sandwich beam with commercially available MRF 132DG fluid as core was fabricated. The modal parameters of the cantilever MRF sandwich beams were determined at different magnetic fields. Further, sinusoidal sweep excitation tests were performed on these beams at different magnetic fields to investigate their vibration suppression behavior. MRF having larger particle size and higher weight fraction of CIP resulted in higher damping ratio and vibration suppression. Finally, optimal particle size and weight fraction of CIP were determined based on the maximization of damping ratio and minimization of weight of MRF. © 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.