Browsing by Author "Chandraker, S."

Now showing 1 - 19 of 19

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.
An experimental investigation of epoxy-based hybrid composites with hexagonal boron nitride and short sisal fiber as reinforcement for high performance microelectronic applications
(John Wiley and Sons Inc, 2022) Agrawal, A.; Chandraker, S.
In the present article, an investigation is presented on epoxy-based composites where the discontinuous phases are microsized boron nitride and sisal fiber (SF). Both the reinforcing materials are surface modified before incorporating them into the epoxy matrix. Hexagonal boron nitride (hBN) surface is treated by silane-coupling agent, whereas the aqueous NaOH solution is used to modify the surface of SF. The effect of fillers on the physical, mechanical, thermal, and dielectric properties of hybrid composites is studied through experimentation. The result shows that the inclusion of hBN increases the thermal conductivity of epoxy appreciably and dielectric constant marginally, while the inclusion of SF reduces the thermal conductivity marginally and dielectric constant appreciably. The maximum thermal conductivity of 1.88 W/m-K is obtained for the combination of 30 wt% hBN and 3 wt% SF. For the same combination, the dielectric constant is 4.57 at 1 GHz, which is almost similar to neat epoxy. Also, other properties like compressive strength, hardness, glass-transition temperature, and coefficient of thermal expansion improve when combinations of ceramic filler and natural fiber were incorporated in the epoxy matrix. Due to outstanding comprehensive properties, epoxy/hBN/SF composites found potential application in wide microelectronic applications. © 2021 Society of Plastics Engineers.
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.
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 spacecraftâ€™s sub-assembly/assembly during AIT activity. Â© 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Development and Characterization of Epoxy-Based Polymeric Composite with Bio-particulates as Filler Material
(Springer Science and Business Media Deutschland GmbH, 2022) Chandraker, S.; Dutt, J.K.; Agrawal, A.; Roy, H.; Rajkumar; Chandrakar, K.; Mishra, V.
The focus of this paper is to develop cheap and unconventional materials for both structural and non-structural applications using eco-friendly bio-wastes. The study used pistachio nutshells (normally disposed of as waste) for fabricating bio-particulate-based polymeric composites. In this investigation, epoxy is taken as matrix material and pistachio nutshells in the form of microparticles are used as filler material. Six different sets of composites with varying filler content up to a maximum of 30 wt% are fabricated by a hand lay-up method. The excellent compatibility and bonding between the matrix and filler material under investigation are confirmed by micrograph obtained from scanning electron microscopy and by Fourier-transform infrared spectroscopy analysis. Physical and mechanical properties are evaluated experimentally as per ASTM. Apart from that, a linear viscoelastic semi-solid model is reported here to understand the mechanical dynamic behaviour of the developed material. On the basis of several test result, the developed composite may find its potential application in light-duty structures efficiently. © 2021, King Fahd University of Petroleum & Minerals.
Dynamic characteristics of a flexible coupling
(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. Copyright � 2019 ASME.
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. Â© Â© 2019 ASME.
Effect of metalloid element on the microstructural and mechanical properties of AlCoCrCuFeNi high-entropy alloys
(Taylor and Francis Ltd., 2024) Chandrakar, R.; Chandraker, S.; Kumar, A.; Jaiswal, A.
The impact of the metalloid element silicon (Si) addition on the microstructural and mechanical properties of the AlCoCuCrFeNiSix high-entropy alloy system is examined in this paper. The alloys were synthesized using a vacuum arc melting route. X-ray diffraction was used to analyse the current high-entropy alloys’ phase formation to comprehend the alloying process’s behaviour. It is evident from the peak pattern of the X-ray diffraction that the inclusion of Si promotes the growth of body-centred cubic structures. The microhardness and wear resistance were increased by increasing the Si content from 0 to 0.9. Si presence enhances the hardness of the alloys and strengthens the grain boundary. Improved hardness and wear resistance results from the enhanced body-centred cubic-phase formation, which poses a barrier to the dislocation movement and prevents further deformation. Furthermore, the inclusion of Si improved corrosion resistance in potentiodynamic polarization measurements. Excellent compressive strength is possessed by all of the high-entropy alloys with Si addition. © 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
Influence of particulate surface treatment on physical, mechanical, thermal, and dielectric behavior of epoxy/hexagonal boron nitride composites
(John Wiley and Sons Inc. cs-journals@wiley.com, 2020) Agrawal, A.; Chandraker, S.
Physical, mechanical, thermal, and dielectric behavior of surface modified hexagonal boron nitride (hBN) in epoxy matrix was investigated in this paper. Effective treatment of microsize boron nitride involved silane coupling agent, (?-aminopropyl)triethoxysilane such that the coating resulted from the treatment amounted to 2% of the weight of silane coupling agent of the treated BN. The present work revealed that the chemical treatment of BN surface could effectively enhance the adhesion between matrix and filler material. The dispersion and wettability of the BN powder in epoxy matrix after surface treatment were improved. These imparted improved physical and excellent mechanical and thermal properties to the developed material. The experimental study on thermal properties of fabricated composites indicated that incorporation of modified particles exhibits improved glass transition temperature. As filler loading increases, coefficient of thermal expansion of composite decreases which further decreases when treated filler were used. Further, appreciable improvement in thermal conductivity is obtained when treated hBN is used in place of untreated one. The dielectric properties are investigated for wide frequency range and filler content and found to be increased with hBN content and decrease with frequency enhancement. Furthermore, mechanical properties of such composites were also largely enhanced when treated fillers were used. With modified properties, the presently developed material is suitable for microelectronic applications. © 2019 Society of Plastics Engineers
Investigation of phase transformation and mechanical properties of silicon addition on AlCrFeMnNi high entropy alloys
(Institute of Physics, 2024) Chandrakar, R.; Chandraker, S.; Kumar, A.; Jaiswal, A.
This paper examines the impact of silicon in the AlCrFeMnNi high-entropy alloy system, focusing on both its microstructural and mechanical properties. Alloys with varying silicon content (x = 0, 0.3, 0.6, 0.9 atomic ratio) were synthesized using vacuum arc melting. The phase formation of these high-entropy alloys was analyzed using x-ray diffraction to comprehend the alloying process behaviour. The findings revealed that the solidification of the AlCrFeMnNi alloy occurred in dendritically, with dendrite cores containing Cr, Fe, and Ni, while interdendritic regions were enriched in Al and Ni after adding Silicon. Increasing the silicon content from 0 to 0.9 led to significant improvements in microhardness and wear resistance. This improvement is attributed to the reinforcement of grain boundaries provided by silicon. The formation of an Al and Ni rich B2 phase is crucial in resisting dislocation motion and preventing further deformation. Additionally, the addition of silicon led to improved corrosion resistance, as demonstrated by potentiodynamic polarization measurements. However, a trade-off was observed between compressive strength and ductility: compressive strength increased with higher silicon concentrations, but at the expense of ductility. © 2024 The Author(s). Published by IOP Publishing Ltd.
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. Â© 2020 Published under licence by IOP Publishing Ltd.
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.
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.
Microstructural and mechanical properties of AlCoCrCuFeNiSix (x = 0 and 0.9) high entropy alloys
(Elsevier Ltd, 2021) Chandrakar, R.; Kumar, A.; Chandraker, S.; Rao, K.R.; Chopkar, M.
In this work, the effect of addition of Si on the phase evolution and mechanical properties of AlCoCrCuFeNiSix alloy system has been studied. The High Entropy Alloys (x = 0 and 0.9) have been synthesised by powder metallurgy route which includes mechanical alloying (MA) and spark plasma sintering. X-ray diffraction technique was performed to understand the alloying behaviour and to investigate the phase formation of the high entropy alloys. The samples after spark plasma sintering comprised mainly of body centered cubic structured phase with a small extent of face centered cubic structured phase. With the addition of silicon, the XRD peak intensity of body centered cubic appears strong compared to the face centered cubic structured phase. Moreover, no intermetallic is observed in AlCoCrCuFeNi high entropy alloy system. However, further accumulation of Silicon results in the evolution of sigma (?) phase. © 2020 Elsevier Ltd
Optimization of tribological parameters to enhance wear and friction properties of Ti6Al4V alloy using Taguchi method
(SAGE Publications Ltd, 2022) Sreesha, R.B.; Chandraker, S.; Kumar, D.
The present study is an endeavor to investigate the wear and friction behavior of Ti6Al4V against alumina (Al2O3) using a pin-on-disc tribometer at room temperature. The tests were performed for a given range of loads (10–90 N) and sliding velocities (0.5–4 m/s) for a sliding distance of 3000 m. The wear rate increased continuously with load and showed transition behavior with respect to the sliding velocity. Minimum friction was observed at the intermediate sliding velocities. Using the Taguchi tool, it was found that the load influenced the wear rate more significantly than the sliding velocity and the behavior was the opposite for the coefficient of friction. A wear model was predicted using regression, and subsequent confirmatory tests were carried out to validate the same. The ex-situ characterization of both worn-out surfaces and wear debris was conducted using Scanning Electron Microscope (SEM) along with the Energy Dispersion Spectroscopy (EDS) to study the surface morphology and level of oxidation, respectively. The wear mechanism was found to be a combination of adhesion, abrasion, oxidation, and delamination wear. The distinct lower wear rates at higher loads and velocities were attributed to the formation of Ti8O15 revealed by the X-ray diffraction (XRD) study. © IMechE 2022.
Phase Evolution of Novel MoNbSiTiW Refractory High-Entropy Alloy Prepared by Mechanical Alloying
(Springer, 2022) Prakash, O.; Chandrakar, R.; Chandraker, S.; Rao, K.R.; Kumar, R.; Kumar, A.; Dubey, V.
Refractory high-entropy alloys (RHEAs) are new types of material that have been developed for high-temperature applications. RHEAs should have enhanced high-temperature strength while maintaining a sufficient level of room-temperature toughness. The phase evolution of novel MoNbSiTiW RHEAs was investigated after mechanical alloying (MA) for 35 h. X-ray diffraction (XRD) was used to analyze the phase evolution, and analysis of particle morphologies was done using a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). XRD results indicate that NbMoSiTiW RHEAs with up to 10 h of mechanical alloying have a stable solid solution phase with body centered cubic (BCC) structure. Further milling of NbMoSiTiW RHEAs promotes the evolution of intermetallic compounds until 35 h of mechanical alloying. The Williamson-Hall process was incorporated for crystalline size and lattice strain measurement and the results show that, after 35 h of mechanical alloying, the crystalline size decreased from 298 nm to 25 nm, and an enhancement in lattice strain was observed from 0.1% to 0.65%. © 2022, The Minerals, Metals & Materials Society.
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. Â© 2021 Author(s).
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. Â© 2018 Elsevier Ltd. All rights reserved.
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. Â© 2021 Author(s).