Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
Browse
9 results
Search Results
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.Item 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 EngineersItem 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 LtdItem 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.Item 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.Item 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.Item 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.Item 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.Item 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.