Faculty Publications
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Publications by NITK Faculty
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Item Study on stacking sequence of plies in green sandwiches for low velocity impact application(Trans Tech Publications Ltd ttp@transtec.ch, 2019) Mahesh, V.; Joladarashi, J.; Kulkarni, S.M.The present paper deals with optimizing the stacking sequence configuration of flexible green composite for cladding application under low velocity impact regime. Initially six configurations of green composite comprising of jute fiber and natural rubber matrix are considered and their energy absorption behaviour and resistance to impact are studied using finite element analysis. The configurations considered are optimized for energy absorption and maximum contact force under low velocity impact condition. From the results it can be concluded that the variation in energy absorbed and sp. energy absorbed among the configurations are negligible and hence the configurations are prioritized based on contact force. JRJRJ configuration provides maximum contact force followed by JRJ, JRRJ, RJRJR, RJRJ and RJR. The configurations with rank 1, 2 and 3 should be taken into consideration for further analysis. Also the damage study shows that the stacking sequence with jute on impact side is better compared to rubber on impact side as tearing type of damage can be observed in sequences with rubber on impact side and no damage is visible with jute on impact side. © 2019 Trans Tech Publications, SwitzerlandItem Comparative study on energy absorbing behavior of stiff and flexible composites under low velocity impact(American Institute of Physics Inc. subs@aip.org, 2019) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.This paper deals with the comparative study on the energy absorbing behaviour of the flexible composites with that of stiff composites aiming at automobile cladding application. Two types of composites namely Jute-Epoxy (JE) laminate and Jute-Rubber-Jute (JRJ) sandwich are chosen for the purpose of study under impact velocity varying from 2.5 m/s to 10 m/s. The study is carried out using commercially available finite element simulation software. The energy absorption and damage behavior of both the composites are studied. From the results, it was found that JRJ sandwich absorbs almost 54%, 51.2%, 58.1% and 61.78% more energy compared to JE laminate for impact velocity of 2.5 m/s, 5 m/s, 7.5 m/s and 10 m/s respectively and exhibits compliant nature as opposed to JE laminate which exhibits brittle nature. The energy absorption ratio of JRJ sandwich is more compared to JE laminate. Thus, the JRJ sandwich composites are expected to provide better energy absorption, reduce damage propagation under low velocity impact, thereby making them a potential material for automobile structural protective claddings. © 2018 Author(s).Item Compressive properties of sandwiches with functionally graded rubber core and jute-epoxy skins(2013) Doddamani, M.R.; Kulkarni, S.The compressive behaviour of a new class of sandwich composite made up of jute fiber reinforced epoxy skins and piece-wise linear fly ash reinforced functionally graded (FG) rubber core is investigated in flat-wise mode. FG samples are prepared using conventional casting techniéue. Presence of gradation is éuantified physically by weight method. This paper addresses the effect of weight fraction of fly ash, core to thickness ratio (C/H) and orientation of jute on specific compressive modulus and strength. In each trial five replicates are tested with lower amount of fly ash below the upper skin of sandwich (rubber-up). Results of experimentation are subjected to statistical analysis of variance (ANOVA) to find the influential factor governing the compressive behaviour. Furthermore piece-wise linear gradation is modeled in finite element and strength values are compared with experimental results. Sandwich sample with fly ash content of 40%, C/H of 0.4 and orientations of 30?/60? registered better performance. Specific strength is observed to increase upto 30% filler content followed by stabilization. Finite element results for strength match very well with experimental ones.Item Comparative study on ballistic impact response of neat fabric, compliant, hybrid compliant and stiff composite(Elsevier Ltd, 2021) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.The present study deals with the experimental approach of finding the ballistic limit of neat jute fabric along with its compliant composite, compliant hybrid composite with and without interleaved natural rubber (NR) sheets and stiff jute epoxy (JE) composite. Mechanism governing the damage in the proposed targets are studied. Ballistic impact tests were carried out by firing a conical projectile using a gas gun apparatus at lower range of ballistic impact regime. The ballistic impact response of the neat jute fabrics along with proposed compliant composites are assessed based on energy absorption and damage mechanism. Results revealed that the complaint hybrid composites exhibit enhanced ballistic response compared to neat jute fabrics, compliant and stiff composites. Inclusion of NR aids affects the ballistic performance of the composite significantly by keeping the composite flexibility. Rubber does not restrict the yarns through which the whole fabric resists against projectile energy. This behavior is contrary to the epoxy matrix, in which only a few yarns in impact zone resist. This difference significantly changes the ballistic performance of stiff composite and compliant hybrid composite. The damage study reveals the various mechanisms responsible for failure in neat fabrics, compliant composites, compliant hybrid composites and stiff composites. Compliant hybrid composites fail due to matrix tearing as opposed to matrix cracking in stiff JE composites indicating that the proposed complaint composites are free from catastrophic failure. Thus, the proposed compliant hybrid composites are best suited for ballistic applications. © 2021 Elsevier LtdItem Development of Sustainable Jute/Epoxy Composite and Assessing the Effect of Rubber Crumb on Low Velocity Impact Response(Taylor and Francis Ltd., 2022) Mahesh, V.; Mahesh, V.; Harursampath, D.; Joladarashi, S.; Kulkarni, S.M.In the current study, the experimental assessment of influence of rubber crumb on the low velocity impact (LVI) behavior of jute epoxy composites are carried out using two types of impactors namely hemispherical and conical. Hand layup technique is used to fabricate the proposed composites. The rubber crumb is incorporated in the epoxy resin with 1.5 wt%, 3 wt%, and 5 wt%. Results revealed that incorporation of 3 wt% of rubber crumb resulted in better LVI response compared to its counterparts. Fractography studies revealed that inclusion of rubber crumb particles enhances the adhesion between resin and fiber, thereby increasing the energy absorption. In addition, they aid in reducing damage area and increasing penetration threshold of proposed composites. The current study’s systematic technique serves as a model for the efficient use and conversion of waste rubber crumb into usable natural fiber reinforced polymer matrix composites for LVI applications. © 2022 Taylor & Francis.