Journal Articles

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    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.
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    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.
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    Influence of redmud on the mechanical, damping and chemical resistance properties of banana/polyester hybrid composites
    (Elsevier Ltd, 2014) Veerasimman, V.; Marimuthu, M.; Manikandan, V.; Nagarajan, N.; Jeyaraj, P.
    A novel hybrid composite was developed with the addition of redmud as secondary reinforcing filler with banana fiber reinforced polyester composites (BFRPCs). The effect of varying parameters such as particle size (4, 6 and 13. ?m) and weight percentage (2, 4, 6, 8 and 10. wt%) of redmud were analyzed on static mechanical, free vibration and chemical resistance properties of hybrid composites. The addition of redmud shown enhanced performance compared to the virgin BFRPCs in all the above said properties. The maximum increase of 50% in mechanical strength was observed for the BFRPCs with the addition of redmud having 4. ?m particle size and 8. wt% of filler content compared to pure BFRPCs. The increased value of fundamental natural frequencies with associated modal damping characteristics of redmud filled BFRPCs were found using half-power band width method. All the fabricated composites performed well against various chemicals and it indicates that the resistance to the weight loss is due to the uniformly distributed redmud. To study the effect of redmud on interfacial bonding between the banana fiber and polyester matrix the Scanning Electron Microscope (SEM) image analysis was performed. © 2014 Elsevier Ltd.
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    Dynamic mechanical analysis and free vibration behavior of intra-ply woven natural fiber hybrid polymer composite
    (SAGE Publications Ltd info@sagepub.co.uk, 2016) RAJESH, M.; Jeyaraj, P.
    Influence of nature of weaving pattern and intra-ply hybridization of natural fibers on dynamic mechanical and free vibration characteristics of woven banana/jute polyester composite has been investigated. Results revealed that basket-type composite has better dynamic properties due to uniform stress distribution in both warp and weft directions. Warp jute fiber and weft banana fiber (WJWB) and both warp and weft banana and jute fiber (WAWBJ) intra-ply hybrid composites have better dynamic mechanical behavior as relatively stronger fiber is oriented along the loading direction. Experimental modal analysis carried out on beam-like samples revealed that warp and weft banana and jute fiber intra-ply hybrid composite has better natural frequencies while huckaback woven and warp banana fiber and weft jute fiber composites have better modal damping factors. © The Author(s) 2015.
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    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.
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    Influence of nature of core on vibro acoustic behavior of sandwich aerospace structures
    (Elsevier Masson SAS 62 rue Camille Desmoulins Issy les Moulineaux Cedex 92442, 2016) Arunkumar, M.P.; Jeyaraj, P.; Gangadharan, K.V.; Mailan Chinnapandi, M.C.
    This paper presents the study of influence of core geometry on vibration and acoustic response characteristics of sandwich panels which are used as aerospace structures. Sandwich panels considered in this research work are: (a) Honeycomb core, (b) Truss and Z core, (c) Foam core. The present study has found that (i) For a honeycomb core sandwich panel in due consideration to space constraint, the better acoustic comfort can be achieved by reducing the core height and increasing the face sheet thickness. (ii) It is demonstrated that, for a honeycomb core sandwich panel, vibration and acoustic response is not sensitive to the cell size. (iii) It is observed that, triangular core gives better acoustic comfort for the truss core sandwich panel compared to other type of core. (iv) For foam core sandwich panels, it is observed that sandwich panel with carbon-epoxy (high stiffness) face sheet radiates less sound in the lower frequency range (0–100 Hz). While the sandwich panel with Titanium (high density) face sheet radiates less sound at the higher frequencies. In order to reduce the preprocessing time and computational effort throughout the analysis in the present study, equivalent 2D elastic properties are calculated and used to find out the vibration and acoustic response characteristics. © 2016 Elsevier Masson SAS
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    Buckling of non-uniformly heated isotropic beam: Experimental and theoretical investigations
    (Elsevier Ltd, 2016) George, N.; Jeyaraj, P.; Murigendrappa, S.M.
    Influence of non-uniform heating on critical buckling temperature of an aluminium beam has been investigated experimentally with the help of a novel experimental set-up developed in-house. Non-linear finite element analysis, considering the initial geometric imperfection, has been carried out to compare the experimentally obtained typical load-deflection curve. The linear critical buckling temperature predicted numerically are validated with analytical solutions. Experimental results revealed that critical buckling temperature of the non-uniformly heated beam greatly differs from the uniformly heated beam. It is also observed that the location of heat source and resulting non-uniform temperature variation influences the critical buckling temperature significantly. © 2016 Elsevier Ltd
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    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.
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    Mechanical characterization of natural fiber intra-ply fabric polymer composites: Influence of chemical modifications
    (SAGE Publications Ltd info@sagepub.co.uk, 2017) RAJESH, M.; Jeyaraj, P.
    The influence of surface treatment (alkali, potassium permanganate, benzoyl chloride and silane) on the mechanical, dynamic mechanical and free vibration properties of intra-ply hybrid banana/jute woven fabric composite has been analyzed. Intra-ply woven fabrics are fabricated by keeping banana yarn in weft direction and jute yarn in warp direction of a basket-type woven fabric. Results reveal that the enhancement of tensile and flexural strengths of the composite due to the chemical treatment is marginal, except for the benzoyl chloride treatment. However, the chemical treatment results in better impact strength compared to the untreated composite. Tensile, flexural and impact strengths of the benzoyl chloride treatment increase by 10%, 30% and 50%, respectively, compared to untreated composite. It is evident from Fourier Transform-Infrared Spectra that benzoyl chloride treatment effectively removes the hemicellulose and lignin content. It is observed that benzoyl chloride and alkali treatment improves the dynamic mechanical characteristics. Experimental modal analysis carried out on intra-ply fabric composites reveals that benzoyl chloride treatment increases the natural frequency significantly compared to the untreated composite. © 2017, © The Author(s) 2017.
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    Mechanical behavior of woven natural fiber fabric composites: Effect of weaving architecture, intra-ply hybridization and stacking sequence of fabrics
    (SAGE Publications Ltd info@sagepub.co.uk, 2018) RAJESH, M.; Singh, S.P.; Jeyaraj, P.
    A comprehensive analysis carried out on the mechanical and free vibration properties of woven natural fiber polymer composites is presented. Jute fabric with three different weave types (plain, basket and herringbone) and intra-ply woven jute-banana fabrics are considered for investigation of the effect of weave type of a fabric and its stacking sequence on mechanical, dynamic mechanical and free vibration properties. Enhancement of the properties is found with the number of layers of fabric and better properties obtained for four layers. Uniform stress distribution along warp and weft direction of fabric with basket weave type lead to better properties compared to other weave types for four-layered composites. Intra-ply hybridization of jute-banana also enhances the mechanical properties but slightly less than the jute-basket fabric composite. The investigations on effect of layer sequence of fabrics revealed improvement in mechanical properties. Layered composite with relatively strong intra-ply fabric as the facing layer and relatively weak jute plain fabrics as the core layer has higher tensile and flexural properties. Experimental modal analysis carried out on beam-like composite laminates reveal that natural frequencies and associated modal damping factor are significantly influenced by stacking sequence and weave type of a fabric. The density of the composite calculated based on Archimedes principle matches well with the theoretical values. © 2016, © The Author(s) 2016.