Faculty Publications

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Author: search.filters.author.Jeyaraj, P.Subject: search.filters.subject.Vibrations (mechanical)

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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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    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 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.
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    Dynamic mechanical and free vibration behavior of natural fiber braided fabric composite: Comparison with conventional and knitted fabric composites
    (John Wiley and Sons Inc. cs-journals@wiley.com, 2018) RAJESH, M.; Jeyaraj, P.
    Dynamic mechanical and experimental modal analysis has been performed on braided yarn woven fabric reinforced polyester composites and results are compared with those of conventional twisted yarn woven fabric and knitted woven fabric composites. The results revealed that storage modulus shows an increasing trend across conventional woven, knitted and braided woven fabric reinforcement, in that order. It is also observed that intra-ply hybridization enhances storage modulus and material loss factor of the conventional woven fabric and knitted woven fabric composites. It is also observed that knitted fabric composites have higher loss factors compared with conventional and braided fabric composites. Experimental modal analysis results reveal that the braided yarn fabric enhances the stiffness of the composite structure and hence results in higher natural frequencies while knitted fabric reinforcement enhances modal loss factor of the composite structure due the spiral orientation of yarns and large gaps associated with between the yarns in kitted fabric. POLYM. COMPOS., 39:2479–2489, 2018. © 2016 Society of Plastics Engineers. © 2016 Society of Plastics Engineers