Faculty Publications

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    Wave interaction with multiple submerged porous structures
    (Springer, 2019) Venkateswarlu, V.; Karmakar, D.
    In the present study, two submerged porous structures under the action of ocean waves are analysed to understand the wave control performance due to porosity parameter. The studies in the first case consider the submerged porous structure kept at finite depth backed by rigid wall at a distance L. The second case explains the two submerged porous structures with sea wall. The numerical study is performed considering the velocity potentials in (i) open water region (seaside), (ii) porous region (primary porous structure), (iii) open water region (in between the porous structures), (iv) porous region (second porous structure) and (v) open water region (lee side). The linearized wave theory is used to analyse the wave interaction with submerged porous structures. The matching conditions are adopted based on continuity of mass and velocity, and the orthogonality condition is used to formulate the boundary value problem, and the eigenfunction expansion method is adopted for the determination of reflection, transmission coefficients, energy loss and wave forces on submerged porous structures. Numerical computation is performed for predicting the wave reflection and transmission from the submerged porous structures for different structure width and angle of incidence conditions. The existence of the porosity and friction causes energy loss and minimum friction; maximum porosity results in high wave transmission and less wave reflection. The significant difference is observed when submerged porous structure is divided into two submerged porous structures with rigid wall. In all the cases, the width of the porous structure is considered similar and is observed to play a predominant role in wave reflection, transmission and stability of the structure. The study will help in the novel economic design of the submerged porous structures for the protection of coastal facilities. © Springer Nature Singapore Pte Ltd. 2019.
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    Ballistic Impact Study on Jute-Epoxy and Natural Rubber Sandwich Composites
    (Elsevier Ltd, 2018) Sangamesh, R.; Ravishankar, K.S.; Kulkarni, S.M.
    Since ages, human beings have used different methods to protect themselves and their armors from the impact of bullets/projectiles by using structures made up of wood, metals, glass and sand bags etc. These protective structures are heavy and incur cost and inconvenience to transport. Of late, they are replaced by structures of polymers and their composites, because of their light weight and good corrosion resistance. Ballistic impact analysis of composite materials is necessary in order to establish their use in military, aerospace and automotive applications either through experimental studies or using modeling techniques. The aim of the present investigation is to model and analyze the behavior of composites for ballistic impact. Residual velocity, energy absorption and ballistic limit for three different materials Jute-Epoxy (JE), Rubber (Ru), Jute-Epoxy-Rubber sandwich (JRE) for three thicknesses (5, 10, 15mm) and at three velocities (150, 250, 350 m/s) is studied. The study exhibits a significant amount of energy absorption in rubber, almost 10 times as compared to JE plate. Also damage observed was ductile in the case of rubber, while brittle in JE. Sandwich composites (JRE) displayed energy absorption and ballistic limit on par with rubber plates. Thus the applicability of these sandwiches in ballistic impact is established as better energy absorbing protective target structures. © 2017 Elsevier Ltd.
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    Study on ballistic energy absorption capability of glass-epoxy and jute-epoxy-rubber sandwich composites
    (Trans Tech Publications Ltd ttp@transtec.ch, 2018) Rajole, S.; Ravishankar, K.S.; Kulkarni, S.M.
    High velocity impact analysis of natural fiber reinforced composites is essential as the trend is focused towards the development of light weight, environment-friendly, non-corrosive and economical materials. At present, the defence, aerospace and automobile sectors are using synthetic fiber composites which are expensive and non-eco-friendly. In the present study ballistic impact of jute-epoxy (JEC), glass-epoxy (GEC), jute-epoxy-rubber (JERC) sandwich composites are simulated with different thickness (1, 2 and 3 mm) and velocity variations (100, 200 and 300m/s) using Finite Element analysis software. Although different approaches to the analysis of the effect response of composite structures are available, numerical modeling is based on strict constitutive models is often preferred because it can provide valuable detailed information about the spatial and temporal distribution of damage during the impact. The ballistic parameters such as energy absorption, ballistic limit and fracture behaviors are predicted. The composite is made of 8 noded linear brick elements and the bullet/projectile is modeled as a discrete rigid element in which deformation behavior, energy absorption and penetration behaviors obtained are clearly represented. The simulation results predicted match well with the analytical results obtained. Among all the combination of the materials simulated, the sandwiches have better ballistic qualities. Energy absorption of sandwich(JERC) was found 67 percentage higher than GEC and 56 percentage higher than JEC laminate. In future, these materials can be the alternative materials for defence sector for bullet proofing. © 2018 Trans Tech Publications, Switzerland.
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    Suitability study of jute-epoxy composite laminate for low and high velocity impact applications
    (American Institute of Physics Inc. subs@aip.org, 2018) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
    This paper discusses the effect of thickness on the energy absorbing ability of the jute-epoxy (JE) laminate under low velocity and high velocity impact conditions. In the present analysis, a parametric study has been carried out choosing three different thickness values of laminate (6 mm, 8mm and 10 mm) and four different velocities each under low (2m/s, 4m/s, 6m/s and 8 m/s) and high velocity (100 m/s, 150 m/s, 200 m/s and 250 m/s) impact conditions. A Damage behavior study has been carried out under both low and high velocity impacts to assess the suitable condition of application for JE laminate. It is found that, the energy absorbing ability of laminate increases with increasing laminate thickness and impact velocity, especially at higher values of impact velocity of the chosen regime. The outcome of the study of damage behavior under low and high velocity impact shows that JE laminate is suitable for low velocity impact applications rather than high velocity impact applications. © 2018 Author(s).
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    Ballistic performance study of kevlar29 fibre reinforced polyester composite
    (Trans Tech Publications Ltd ttp@transtec.ch, 2019) Sangamesh, R.; Hiremath, H.; Ravishankar, K.S.; Kulkarni, S.M.
    Ballistic qualities of the material are important for the military defence barrier application for protection of military persons, their vehicles and equipment. In the present investigation ballistic performance of Kevlar29 fibre reinforced polyester composite (KPC) is analysed. A definite parametric study, taking into account various shape of projectiles (Flat-F, Spherical-S and Conical-C) impact on the composite target of different thicknesses (12, 16 and 20 mm). Impact velocity of the projectile considered for analysis 100-400 m / s. Ballistic parameters such as residual velocity, deformation and penetration behaviour are predicted. Conical projectile has more effect on the composite target compared to other projectile. Composite thickness influenced the energy absorption. The thickness increase from 12 mm to 20 mm which leads to increase in the energy absorption by almost 20%. © 2019 Trans Tech Publications, Switzerland.
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    Influence of laminate thickness and impactor shape on low velocity impact response of jute-epoxy composite: FE study
    (Elsevier Ltd, 2019) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
    This paper aims at numerical and parametric investigation on the outcome of low velocity impact (LVI) response of jute/epoxy (JE) composite of varied thickness subjected to impact at varied velocity of impact within LVI regime using different shaped impactors. The JE composite laminate with varying thickness of 6 mm to 10 mm is subjected to LVI at impact velocity varying from 2 m per second (mps) to 8 mps using impactors of hemispherical (HS), flat (F) and conical (C) shapes. Modelling and simulation of the proposed JE composite laminate is achieved using explicit software available commercially with target as deformable material and the impactor as a rigid body. Simulations are carried out for available possible combination of thickness, impact velocity and impactor shapes. Results reveal that thickness is one of the crucial factors that decide the LVI response of the proposed composite laminate. Laminate impacted with conical shaped impactor results in maximum absorption of energy and the laminate impacted with flat shaped impactor results in bigger and immediate damage. © 2019 Elsevier Ltd.
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    Study on ballistic characteristics of glass-epoxy-rubber sandwiches
    (Trans Tech Publications Ltd ttp@transtec.ch, 2020) Sangamesh, R.; Hiremath, H.; Ravishankar, K.S.; Kulkarni, S.M.
    This article focuses on the Finite Element (FE) analysis of the ballistic performance of the polymer composites. These composites consisting of natural rubber (NR), glass-epoxy (GE) and glass-rubber-epoxy (GRE) sandwich of different thicknesses (3, 6 and 9 mm) under the impact of the conical nose projectile for a velocity variation of (180, 220 and 260 m / s). FE modeling was carried out to forecast the energy absorption, ballistic limit velocity and failure damage mode of the target material. The significant influence of thickness, interlayers and sandwiching effect was studied: the lowest ballistic limit was obtained for 3 mm thick GE. The energy absorption capacity of GRE sandwich was highest among the natural rubber and GE. The work can be extended for the experimental validation purpose so that these polymer composite materials could be utilized in the defense sector for bullet-proofing. © 2020 Trans Tech Publications Ltd, Switzerland.
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    Parametric study on impact behaviour of sisal and cenosphere reinforced natural rubber-based hybrid composites: FE approach
    (Elsevier Ltd, 2021) Rajkumar, D.; Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
    This paper aims to study the impact analysis of sisal fiber and cenosphere filler reinforced natural rubber composite using commercially available finite element software. The proposed green composite is studied for impact behaviour by varying the weight percentage of the cenosphere filler particles in a natural rubber sheet. Composite is modelled with stacking sequence sisal-rubber-sisal using finite element software and impacted by three different rigid impactors (Conical, Hemi-spherical and Flat) at the velocity of 8m/s. Modelling and simulation of this proposed composite laminate are solved using the explicit dynamic solver of Abaqus Computer-Aided Engineering Finite Element Modelling. The results of the low-velocity impact of the proposed green composite with sisal-rubber-sisal stacking sequence exhibit better energy absorption by varying the weight percentage of the Cenosphere. Also, the energy absorbed by laminate was more for the Conical impactor than the Hemi-spherical and Flat impactors and the extent of damage is more when impacted by the Flat impactor due to its larger contact area. © 2021 Elsevier Ltd. All rights reserved.
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    The effect of the particle shape and strain rate on microstructure and compressive deformation response of pure Ti-foam made using acrowax as space holder
    (Elsevier Ltd, 2015) Mondal, D.P.; Patel, M.; Jain, H.; Jha, A.K.; Das, S.; Dasgupta, R.
    Titanium foams of varying amount of porosities have been made using acrowax bits as a space holder through powder metallurgy route. Two types of Ti-particles were used: (i) angular and (ii) spherical in order to see the effect of particle shape on microstructure and deformation behavior. The compressive deformation behavior of Ti-foams with varying porosities and type of particles are studied under different strain rates. It is observed that the microstructural characteristics of Ti-foam varied marginally with the shape of Ti-particles. But the shape of particles influenced reasonably the deformation responses of Ti-foam. The plateau stress, modulus and energy absorption follow power law with relative density irrespective of shape of Ti-particles. All these parameters in Ti-foams are almost invariant to the strain rate. The empirical constants associated with different empirically developed power law relations are different for different shape of Ti-particles. © 2014 Elsevier B.V.
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    An experimental investigation on low-velocity impact response of novel jute/rubber flexible bio-composite
    (Elsevier Ltd, 2019) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.
    This paper presents an experimental investigation on low velocity impact (LVI) behaviour of flexible biocomposite laminates with different stacking sequence namely jute/rubber/jute (JRJ), jute/rubber/rubber/jute (JRRJ), jute/rubber/jute/rubber/jute (JRJRJ) and subjected to different impact energy levels using a conical shaped impactor. The performances of the proposed flexible composites are evaluated based on their energy absorption, peak force, coefficient of restitution (CoR), energy loss percentage (ELP) and failure behavior. Results indicated that JRJ provides better energy absorption and JRJRJ provides better damage resistance when subjected to LVI. Microscopic analysis revealed that the flexible composites fail mainly due to the tearing mechanism of the matrix as opposed to cracking in case of conventional stiff composites. It was also found that flexible composites are free from delamination. Compared to conventional stiff composites, there is no catastrophic failure observed in the proposed flexible composite. The overall performance evaluation of these proposed flexible composites indicates that these flexible composites can be potential sacrificial materials such as claddings used to protect primary structural components subjected to LVI. The systematic methodology employed in the present study serves as a benchmark for the effective utilization and selection of flexible composites for LVI applications. © 2019 Elsevier Ltd