Journal Articles
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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 Performance study of jute-epoxy composites/sandwiches under normal ballistic impact(China Ordnance Society, 2020) Rajole, S.; Ravishankar, K.S.; Kulkarni, S.M.This study is undertaken to explore the use of natural fiber Jute-epoxy (JE), Jute-epoxy-rubber (JRE) sandwich composite for ballistic energy absorption. Energy absorbed and residual velocities for these composites are evaluated analytically and through Finite Element Analysis (FEA). FE analysis of JE plates is carried out for different thicknesses (3, 5, 10 and 15 mm). JE plates and JRE sandwiches having the same thickness (15 mm) are fabricated and tested to measure residual velocity and energy absorbed. The analytical results are found to agree well with the results of FE analysis with a maximum error of 9%. The study on JE composite plate reveals that thickness influences the energy absorption. Experimental and FE analysis study showed that JRE sandwiches have better energy absorption than JE plates. Energy absorption of a JRE sandwich is about 71% greater than JE plates. Damages obtained from FEA and testing are in good agreement. SEM analysis confirms composites failed by fiber rupture and fragmentation. © 2019 The AuthorsItem 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 Development of rubber-sand composite for enhanced impact resistance: Implications of vulcanization(Elsevier B.V., 2024) Doddamani, S.; Kulkarni, S.M.; Joladarashi, S.; Gurjar, A.K.; Mohan Kumar, T.S.Developing rubber-sand composites for enhanced impact resistance faced challenges in material selection, optimisation of vulcanisation, interfacial bonding, and understanding underlying mechanisms. This study provides insights into the effect of vulcanisation on the energy absorption of rubber-sand composites and the potential benefits of adding sand particles as reinforcement, sulfur as a vulcanising agent and carbon black as reinforcement filler. Rubber-sand composites are made from the vulcanisation of natural rubber latex and reinforced with sand particles. Taguchi's design of experiments was used to vary the contents of sulfur (2, 3 and 4) and carbon black (30, 40 and 50) parts per hundred rubber (phr) and sand particles (0, 5 and 10 vol%). After vulcanisation, the composite blocks were prepared using the hot compression moulding technique for experimentation. The shore A hardness and low-velocity drop weight tests have been carried out to investigate the Rubber-sand composite's hardness and energy absorption properties, respectively. The results showed that the increment in the sulfur content increases the hardness of the rubber-sand composite. Additionally, sand particles and carbon black improved the composite's shore A hardness and energy absorption. Multiscale modelling techniques effectively simulated the experimental behaviour of the rubber-sand (Ru-San) composite, with a 3 – 11% error, demonstrating its capability to capture the structural response and damage characteristics under projectile impact conditions. The optimised composite has potential applications in industries that require impact resistance, such as the military, automotive and sports industries. © 2024 Karabuk UniversityItem Experimental and numerical investigation on low-velocity impact response of sandwich structure with functionally graded core(John Wiley and Sons Inc, 2024) Mohan Kumar, T.S.; Joladarashi, S.; Kulkarni, S.M.; Doddamani, S.The present research investigates optimizing the impact resistance of functionally graded sandwich structures using experimental and numerical approaches. The low-velocity impact (LVI) responses of functionally graded sandwich composite (FGSC) with different configurations with skin material jute/rubber/jute (JRJ) and core material having epoxy and sea sand by volume fraction of sea sand at 0%, 10%, 20%, and 30%. Sandwich structures were impacted with LVI (5.89, 10.92, and 15.18 m/s), with the impactor dropped from heights of 0.5, 1, and 1.5 m with precompressed spring loads. FGSC samples are considered a deformable body, and the impactor is modeled as a rigid body using commercially accessible dynamic explicit software. The burn-out test and weight method were used to test the core's gradience; both methods' results substantially matched, and the variance in gradation could be observed. The proposed sandwich structure characteristics are examined by energy absorption, peak force, energy loss percentage, and coefficient of restitution. Results showed that SC30S provides greater energy absorption and superior damage resistance when tested on LVI. To evaluate the accuracy of experimental findings in predicting the indentation behavior of the sandwich structure, the finite element analysis was used to compare with the experimental results. According to the examination of these proposed FGSC overall performance, they could potentially be employed as sacrificial materials for LVI applications like claddings to shield major structural components. The systematic approach used in this work serves as a standard for choosing and using FGSC effectively for LVI applications. Highlights: Low-velocity impact behavior of sandwich structures was investigated. Combining flexible skin and epoxy core enhances energy absorption. Based on impact energy levels, impact damage areas were determined. Examined sandwich structure advantages in structural and aerospace uses. In terms of time and cost, the numerical analysis method would be useful. © 2023 Society of Plastics Engineers.Item Enhancing energy absorption in rubber–sand (Ru–San) composite blocks against ballistic impact: a multi-objective optimisation approach(Springer Science and Business Media B.V., 2024) Doddamani, S.; Kulkarni, S.M.; Joladarashi, S.; Mohan Kumar, T.S.; Gurjar, A.K.This study focuses on optimizing process parameters to minimize the thickness of Ru–San composite blocks against high-velocity impact, aiming to enhance projectile energy absorption, particularly in military trench systems. The critical challenge in developing composite blocks as potential sandbag replacements for trench-bunker systems is optimizing their thickness for improved energy absorption during high-velocity impacts. By employing an optimization technique, this study seeks to determine the minimum thickness of the rubber–sand composite block capable of withstanding the full kinetic energy of a projectile without piercing, thereby advancing protective measures in military and security applications. The material used is a rubber–sand composite, consisting of 00 to 20 wt% of sand particles with various sizes ranging from 250 to 750 μm. The optimisation approach employed in this study includes screening design, Vikor and analytic hierarchy process of optimisation techniques. Finite element simulation is used to model the projectile's impact on the rubber–sand composite block and to analyse the energy absorption behaviour of the material under high-velocity impact. The results of this study show that process parameters such as the thickness of the target, wt% of sand, and size of sand particles significantly impact the energy absorption of the rubber–sand composite block. The optimised parameters are determined to be a thickness of 40 mm, 20 wt% of sand, and sand sizes of 750 μm. The findings of this study have important implications for the design and development of materials that can effectively withstand high-velocity impact, particularly in the field of military defence. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.