Faculty Publications
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Publications by NITK Faculty
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Item Mechanical and Thermal Properties of Sisal Fiber-Based Composites(wiley, 2021) Mishra, V.; Agrawal, A.; Chandraker, S.; Sharma, A.Natural fibers have attracted the scientific community toward their usage as reinforcement in polymeric composites mainly because of multiple benefits such as low cost, huge/easy availability, easy processing, and growing concern toward environmental awareness as they are biodegradable. Reinforcing natural fibers is an efficient approach toward reducing the consumption of nonbiodegradable plastic material. Also, natural fibers are promising reinforcing materials that can replace different synthetic fibers. Among the various natural fibers available, sisal fiber as reinforcement in a polymeric matrix is a strong competitor. Sisal fiber has several advantages like they are the widely used natural fiber and has the second-largest consumption across the world after cotton. It has high strength with good durability. It also has a good percentage of elongation before the break and does not deteriorate quickly in salty water. These fibers are smooth and straight with a high degree of inflexibility. Sisal represents around 2% of the total cultivation among plant fibers. In this regard, the present chapter focuses on sisal fiber as reinforcement with different polymeric matrices. The main emphasis is on the mechanical and thermal behavior of composite understudy and applications of this category of composites in various fields. A review of selected work on the research of sisal fiber with polymer matrix is the content of this chapter. © 2022 WILEY-VCH GmbH, Boschstr. 12, 69469 Weinheim, Germany.Item Melting and casting route(De Gruyter, 2023) Chandrakar, R.; Prakash, O.; Kumar, R.; Tiyyagura, H.R.; Chandraker, S.The melting and casting route is the most common and relatively cheap route of production of high-entropy alloys. In this route, the constituent elements are mixed in liquid state. Multicomponent alloys in the shape of buttons, rods, ribbons, and bars have been created using the melting and casting route, with various cooling rates. Vacuum arc melting is the most common melting and processing process. This chapter reviews melting and casting routes and related synthesis techniques in manufacturing of high-entropy alloys. © 2023 Walter de Gruyter GmbH, Berlin/Boston. All rights reserved.Item Basic alloying elements used in high-entropy alloys(De Gruyter, 2023) Chandrakar, R.; Sridhar, K.; Sahu, P.S.; Chandraker, S.; Gupta, P.K.The mechanical characteristics of high-entropy alloys (HEAs) can be improved by a variety of alloying elements; however, it is unclear how the alloying of various elements affects the changes in the microstructure and the mechanical properties of HEAs. The alloying elements like Cr, V, Ti, Zr, and Hf regulate the melting temperature, lattice constant, and the mass density of HEAs. The electrical structure and the mechanical characteristics of HEAs are significantly impacted by the valence electron concentration. High VEC can enhance mechanical characteristics while decreasing its ductility. Ti significantly affects ductility, while Cr-alloying significantly affects the mechanical characteristics of HEAs. Our findings offer the fundamental understanding required to direct the development of HEAs with superior mechanical characteristics. © 2023 Walter de Gruyter GmbH, Berlin/Boston. All rights reserved.Item Physical, mechanical and sliding wear behavior of solid glass microsphere filled epoxy composites(Elsevier Ltd, 2018) Agrawal, A.; Chandraker, S.; Sharma, A.Performance of epoxy based composites filled with micro-size solid glass microsphere (SGM) is reported in this work. The main emphasis of the present work is on the common trends detected in properties of epoxy/SGM composites. For physical property, densities of all the fabricated samples were presented.Glass micro-sphere filled epoxy composites haveless porosity. They also exhibit improvedmicro-hardness, flexural and impact strength, though tensile strength is compromised marginally. Further, sliding wear performance of the fabricated composites with respect to filler content, sliding velocity and applied force were studied.With improved physical, mechanical and sliding wear, the presently fabricated composites found its potential application where wear predominated. © 2018 Elsevier Ltd. All rights reserved.Item Dynamic characteristics of a flexible coupling(American Society of Mechanical Engineers (ASME) infocentral@asme.org, 2019) Aggarwal, M.; Dutt, J.K.; Chandraker, S.Flexible couplings are used to transmit power between two shafts and accommodate, more realistically, a combination of parallel, axial and angular misalignments, between them. Presence of misalignment of certain degree is considered unavoidable. The coupling also attenuates the transmission of fluctuation of torque and speed from one rotor to the other by flexing itself, and is thus helpful in providing nearly smooth transmission of speed and torque. However, in this process, the dynamic behavior of the rotors is also influenced by the coupling characteristics, as the coupling incorporates a flexible damped intermediate member between the shafts it couples. A detailed literature survey has shown that researchers so far have not attempted to find out the dynamic characteristics, the stiffness and damping of a coupling, and, instead, the effect of misalignment (combination of parallel and angular misalignment) is considered to generate forces independent of the coupling characteristics. This paper attempts to find out an analytical model for the dynamic characteristic of segmented link coupling in terms of suitable non-dimensional coefficients to generate the characteristics of a coupling element which may be used for dynamic analysis of coupled rotor shaft system. © © 2019 ASME.Item Mechanical and Thermal Behaviour of Epoxy/Hexagonal Boron Nitride/Short Sisal Fiber Hybrid Composites(Institute of Physics Publishing helen.craven@iop.org, 2020) Agrawal, A.; Chandraker, S.; Sharma, A.Hybrid composite i.e. surface modified hexagonal boron nitride (hBN) and short sisal fiber reinforced in epoxy matrix is fabricated using hand lay-up method. The effect of surface modified hBN filler and sisal fiber content on mechanical and thermal properties of epoxy based hybrid composites were investigated in this paper. The main aim of the investigation is to develop a material which can found its application in microelectronic components. As per the requirement of microelectronic industry, the material should possess high thermal conductivity. Hence, thermal conductivity of epoxy increases with increase in hexagonal boron nitride content. Inspite of insulative nature of sisal fiber, the study shows that its inclusion in combination with hBN enhances the thermal conductivity if the content of both the fillers were properly selected. Other thermal property like coefficient of thermal expansion and glass transition temperature appreciably improves when combination of fillers were added in epoxy matrix. Mechanical properties under study i.e. tensile strength and compressive strength also enhances when combination of sisal fiber and hBN were incorporated as compared to when single filler hBN were used. Hence, usage of hybrid filler as reinforcement in epoxy improve overall mechanical and thermal property of the developed material. © 2020 Published under licence by IOP Publishing Ltd.Item Design Analysis and Experimental Validation of Modular Handling System for Satellite Ground Application(Springer Science and Business Media Deutschland GmbH, 2021) Srinivasa, G.A.; Srivastava, S.; Chandraker, S.Assembly Integration and Testing (AIT) of spacecraft involves a large number of handling operations which are carried out with the help of spacecraft handling system, it is one of the major hardware in Mechanical Ground Support Equipments (MGSEs). The conventional type of handling system consists of mild steel beam section and required many operations like drilling and welding for final hardware realization. Over the conventional handling system, a novel Modular Handling System (MHS) using aluminum extruded complex cross-section profiles with high strength-to-weight ratio is presented. The 1D beam FEA of these profiles gives only approximate results like maximum stress and deformations, so to analyze the assemblies for detailed stress distribution we need to adapt 3D/2D meshing but 3D meshing is complex for these cross sections and requires more solver time. Therefore, an approximation approach is adopted by using 2D shell element meshing over 1D element by maintaining moment of inertia to that of original profile of each cross section, and validated under the cantilever beam with point load condition of FEA results and compared with the analytical calculations. With confidence of these results the present work aimed to analyze MHS by using 2D mesh and perform linear static FEA to determine stresses and deflection. Further, MHS hardware is fabricated, assembled, and realized for experimental validation using strain gages with static loading test facility, and results are compared with finite element simulation results and found close match. The experimental validated MHS hardware successfully utilized for lifting the spacecraft’s sub-assembly/assembly during AIT activity. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Physical and mechanical properties of epoxy reinforced with pistachio shell particulates(American Institute of Physics Inc., 2021) Chandraker, S.; Agrawal, A.; Prakash, P.; Khan, I.A.; Sharma, A.Recently, natural fillers have gain huge interest among the academic researchers and scientists to be used as potential reinforcement material in polymeric matrix composites. The various reasons which attract the scientific community toward it usage in polymer composites are its low cost, ample availability, easy processing and the most important is the growing concern towards environmental awareness as they are bio-degradable. Reinforcing natural fillers is also an efficient approach towards waste management as most of the promising natural fillers were dumped if not used. Following the similar trend, an attempt has been made to utilize pistachio shells as a filler material in polymeric resin for developing a composite body. Pistachio shell with particle size 75 micron is used with epoxy matrix in present investigation. Six sets of epoxy based composites are fabricated using hand lay-up method by varying the filler content upto 30 wt. %. Density of the composites is evaluated using Archimedes principle. Micrographs are taken to visualize the compatibility between filler and matrix body. Tensile strength, compressive strength, flexural strength and hardness are the various mechanical properties evaluated of the developed materials. From the experimental analysis, it has been found that, all the mechanical properties of the composite under consideration increases with filler content. Though increase in density is also observed with filler loading but the increment is marginal. On the basis of experimental findings, it can be concluded that the developed material can be gainfully found its application in light duty structures. © 2021 Author(s).Item Room temperature sliding wear behavior of Ti6Al4V: A review(American Institute of Physics Inc., 2021) Sreesha, R.B.; Kumar, D.; Chandraker, S.; Agrawal, A.High strength-to-weight ratio, high temperature stability, and bio-compatibility makes Ti6Al4V alloy an interesting choice for aerospace, automobile, chemical, and bio-medical industries. In spite of the several attractive properties, the application of the alloy is restricted in sliding interfaces. As a result, many studies, involving surface modifications of the alloy or the tribo-pair in general have surfaced for improvement in tribological properties. The details of tribological behavior of un-modified Ti6Al4V alloy in various operating and environmental conditions, can act as an initial data for the future researches aimed at improving its tribological properties. Thus, the present review is an attempt to put together the studies conducted to evaluate the sliding wear behavior of Ti6Al4V in both dry and lubricated condition at the room temperature. © 2021 Author(s).Item A review on modelling and dynamic analysis of viscoelastic rotor systems(Emerald Publishing, 2022) Ganguly, K.; Chandraker, S.; Roy, H.Purpose: The purpose of this study is to bring down collective information about various issues encountered in modelling of rotor systems. Design/methodology/approach: The most important and basic part of “rotor dynamics” is the study related to its different modelling techniques which further involves the analysis of shaft for understanding the system potential, competence and reliability. The issues addressed in this study are classified mainly into two parts: the initial part gives out a vast overview of significant problems as well as different techniques applied to encounter modelling of rotor systems, while the latter part of the study describes the post-processing problem that occurs while performing the dynamic analysis. Findings: The review incorporates the most important research works that have already placed a benchmark right from the beginning as well as the recent works that are still being carried out to further produce better outcomes. The review concludes with the modal analysis of rotor shaft to show the importance of mathematical model through its dynamic behaviour. Originality/value: A critical literature review on the modelling techniques of rotor shaft systems is provided from earliest to latest along with its real-time application in different research and industrial fields. © 2021, Emerald Publishing Limited.