Faculty Publications
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Item 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).Item 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.Item 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.Item 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 LtdItem Damage mechanics and energy absorption capabilities of natural fiber reinforced elastomeric based bio composite for sacrificial structural applications(China Ordnance Industry Corporation, 2021) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.The present study deals with the experimental, finite element (FE) and analytical assessment of low ballistic impact response of proposed flexible ‘green’ composite make use of naturally available jute and rubber as the constituents of the composite with stacking sequences namely jute/rubber/jute (JRJ), jute/rubber/rubber/jute (JRRJ) and jute/rubber/jute/rubber/jute (JRJRJ). 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 proposed flexible composites are assesses based on energy absorption and damage mechanism. Results revealed that inclusion of natural rubber aids in better energy absorption and mitigating the failure of the proposed composite. Among the three different stacking sequences of flexible composites considered, JRJRJ provides better ballistic performance compared to its counterparts. The damage study reveals that the main mechanism of failure involved in flexible composites is matrix tearing as opposed to matrix cracking in stiff composites indicating that the proposed flexible composites are free from catastrophic failure. Results obtained from experimental, FE and analytical approach pertaining to energy absorption and damage mechanism agree well with each other. The proposed flexible composites due to their exhibited energy absorption capabilities and damage mechanism are best suited as claddings for structural application subjected to impact with an aim of protecting the main structural component from being failed catastrophically. © 2020 The AuthorsItem Comparative study on low velocity impact behavior of natural hybrid and non hybrid flexible thermoplastic based composites(SAGE Publications Ltd, 2023) Kumbhare, K.; Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.The current study attempts to evaluate the low-velocity impact (LVI) behavior of jute and banana fiber-based hybrid and non hybrid green composites. The proposed composites are fabricated using compression moulding method with variety of positioning of layers namely jute-rubber-jute-rubber-jute (JRJRJ), banana-rubber-banana-rubber-banana (BRBRB), jute-rubber-banana-rubber-jute (JRBRJ) and banana-rubber-jute-rubber-banana (BRJRB). Thus developed composites are subjected to LVI testing using conical and hemispherical shaped impactor in drop weight impact testing machine and different impact velocities of 5 m/s, 10 m/s and 15 m/s. Based on the ability of the proposed composites to absorb energy, coefficient of restitution (CoR), energy loss percentage (ELP), and failure behaviour, the suggested flexible composites’ performances are assessed. The study reveals that JRJRJ composite exhibits better energy absorption capability and BRBRB exhibits least energy absorption capability compared to its counterparts. The damage study reveals that hemispherical impactor leads to more damage area due to its larger contact area whereas, conical impactor results in local penetration. Results reveals that inclusion of jute fiber as reinforcement results in better LVI properties compared to banana fiber. It is also clear that the presence of a compliant matrix improves energy absorption and damage resistance in flexible composites. © The Author(s) 2022.Item Experimental investigation of the in-plane quasi-static mechanical behaviour of additively-manufactured polyethylene terephthalate/organically modified montmorillonite nanoclay composite auxetic structures(SAGE Publications Ltd, 2023) Mahesh, V.; Maladkar, P.G.; Sadaram, G.S.S.; Joseph, A.; Mahesh, V.; Harursampath, D.Apart from the inherent anomalous behaviour under tensile and compressive structures, auxetic structures have shown improved energy absorption characteristics that are of prime interest to various fields of study. This is further exemplified by additive manufacturing (AM) techniques and polymer composites to tailor the shape, geometry and form of these structures. Consequently, this paper aims to characterise the in-plane compressive behaviour and negative Poisson’s ratio (NPR) of the most prominent auxetic structures fabricated additively used polymer nanocomposite materials. The study incorporates the use of glycol-modified polyethylene terephthalate (PETG) and nanocomposites of PETG filled with organically modified montmorillonite (OMMT) nanoclay particles to produce auxetic structures fabricated through fused filament fabrication (FFF). Different structures such as hexagonal re-entrant honeycomb structures, peanut-shaped honeycombs, chiral honeycomb structures and missing rib structures are characterised for their compressive performance through experimental approaches involving mechanical testing and digital image correlation (DIC). Different parameters such as the peak crushing strength, average crushing strength, NPR, specific energy absorption (SEA), and crush force efficiency (CFE) of these structures are evaluated at different strain rates/loading rates for varying concentrations of nanoclay and PETG. It is observed that higher loadings of nanoclay particles lower the compressive strength of the structures. Additionally, the NPR decreases with increasing strain rates and is also influenced by the composition and the resultant stiffness. Moreover, the geometrical parameters of the structure largely influence its strain energy absorption. The results have shown that such material-structure combinations can produce structures of high-performance capabilities suitable for aerospace applications. © The Author(s) 2022.Item Low-velocity impact characterization of polyurethane rubber/nano-clay enriched sustainable sandwich composites: Synergy of experimentation and simulations(John Wiley and Sons Inc, 2024) Gowda, D.; Mahesh, V.; Mahesh, V.; Ravishankar, K.S.This research proposes a novel sustainable composite using basalt (B), hemp (H) and polyurethane rubber (Pu) reinforced in nano clay functionalised epoxy matrix for sacrificial structural applications prone to low-velocity impact (LVI). To this end, symmetric and asymmetric laminates such as HHHH, BBBB, BHHB, BHPuHB, BBPuHH and BPuBPuHPuH are fabricated using compression molding techniques and subjected to LVI at three different impact energies of 19.66, 39.39, and 59.05 J. The hemp fibers were treated with NaOH solution before fabrication. Material characterization such as X-ray diffraction, Raman spectroscopy and morphological studies has been carried out. The impact and post-impact properties of the proposed composites are experimentally evaluated and validated with the finite element (FE) results. The effect on the residual tensile strength degradation of laminates at different interlayers and energy levels is also investigated using the Caprino analytical model. The barely visible impact damages (BVID) are investigated through non-destructive dye-penetration tests, which facilitate easy identification of the prominent LVI damages like “Plateau” and “Cliff-drop” impressions. Based on the impact energy absorption and residual tensile strength, proposed laminates followed BHPuHB > BBBB > BHHB > HHHH. The experimentation suggests that Polyurethane core laminates support maximum impact energy absorption by favoring a structural change in interlayers. Also, the residual tensile strength decreases as impact velocity increases. Highlights: Low-velocity impact behavior of sustainable composites is experimented. Basalt, hemp and polyurethane rubber are reinforced in nano clay epoxy matrix. A FE framework to validate the experimentation is proposed. Dye penetrant NDT is adopted to investigate the damages. Morphological studies are conducted to understand LVI responses. © 2024 Society of Plastics Engineers.