Journal Articles

Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884

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Author: search.filters.author.Murigendrappa, S.M.

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    A comparison of different methods for determination of coupling factor and velocity response of coupled plates
    (2013) Pankaj, A.C.; Sastry, S.; Murigendrappa, S.M.
    Coupling loss factors (CLF) and velocity responses has been computed for two plates joined in a 'L' junction configuration using Statistical Energy Analysis. The analyses have been carried out to study the effects of internal loss/damping factor on the coupling factors. The effects of plate widths on the coupling factors and velocity responses at high frequencies has also been studied. The statistical energy parameters have been computed using analytical wave approach, finite element method and Free-SEA software. The studies have revealed that the coupling factor computed by the wave approach is independent of the internal loss factor as compared to the values computed using finite element method, wherein CLF increases linearly as the internal loss factor varies from a zero value, followed by a transition region and converges to the values obtained by the analytical wave approach and remains insensitive to changes at higher values of damping. The results obtained from the studies signify the effects of internal loss/damping factor and plate widths on proper selection and usage of the above mentioned methods for the estimation of coupling factors and velocity responses using statistical energy approach. © Vibroengineering.
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    Experimental investigation on thermally enhanced machining of high-chrome white cast iron and to study its machinability characteristics using Taguchi method and artificial neural network
    (Springer-Verlag London Ltd, 2014) Ravi, A.M.; Murigendrappa, S.M.; Mukunda, P.G.
    Machining of hard-to-wear materials such as high-chrome white cast iron (HCWCI) and high-manganese steels is an uphill task when conventional route followed. Alternatively, thermally enhanced machining (TEM) can be used to minimize the tooling cost very effectively. This paper presents the detailed study of TEM of HCWCI in which the effect of cutting parameters and surface temperature of the stock material on machinability characteristics (cutting forces and surface roughness) are analyzed using ANOVA and artificial neural network (ANN). The experimental work was conducted to follow Taguchi techniques. HCWCI is finding newer applications in mining; mineral processing industries were the workpiece in the machining studies using cobalt-based cubic boron nitride insert tool. Localized heat was added at the tool-work interface which softens the metal and eases the machining operation. The influences of the control factors on the process responses have been analyzed using analysis of variance (ANOVA), and the results are correlated using ANN. Linear regression was used to establish the relation between the control parameters and the process responses. The results show that TEM causes easy shearing of the material, leading to the reduction in cutting forces with expected improvement in tool life and surprisingly good surface finish. The confirmation tests suggest both second-order regression and ANN which are better predictive models for quantitative prediction of TEM of HCWCI, and ANN is more accurate of the two. Also, it was proved that oxy-LPG flame heating is an economical option compared to laser-heated machining in hard turning process. © 2014 Springer-Verlag London.
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    Machinability investigations on high chrome white cast iron using multi coated hard carbide tools
    (Springer India sanjiv.goswami@springer.co.in, 2014) Ravi, A.M.; Murigendrappa, S.M.; Mukunda, P.G.
    This study investigated the performance of multilayer hard coated carbide tool and multi-response optimization of the turning process for an optimal parametric combination to yield the minimum cutting forces and machining power with a maximum material removal rate (MRR) using Taguchi and artificial neural network (ANN) methods. In recent times, high chrome white cast iron finds increasing applications in aerospace, mining, mineral process industries. Its machinability using carbide insert (TiC/TiCN/Al2O3) cutting tool has been studied. The influences of cutting parameters on the cutting forces, MRR and machining power of the process have been analyzed using analysis of variance and the results are correlated using ANN. Linear regression method was used to establish the relation between the cutting parameters and the process responses. The confirmation test reveals that, the accuracy of prediction of ANN is better than that of the regression analysis. In view of the good performance of the carbide tools (at optimum conditions), it can replace the cosly CBN, with improved economic benefits. © 2014 Indian Institute of Metals.
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    Experimental and Analytical Based Investigations on Machinability of High-Chrome White Cast Iron Using CBN Tools
    (Springer, 2015) Ravi, A.M.; Murigendrappa, S.M.; Mukunda, P.G.
    High-chrome white cast iron (HCWCI) is one of the hardest metals used in the process and mining industries faces tough challenge in metal cutting. Focusing on this issue, influence of cutting parameters (e.g., cutting speed, depth of cut, feed rate) on machinability characteristics (e.g., cutting forces, surface roughness, material removal rate, machining power) of HCWCI has been investigated by experimentally and analytically using cubic boron nitride (CBN) cutting tools. Experimentation is carried out in conjunction with the Taguchi techniques and the influence of each cutting parameter of the process has been analyzed by analytical tools; analysis of variance, regression technique and artificial neural networks (ANNs). The study reveals depth of cut has the highest contribution on the cutting forces, and cutting speed on surface roughness and machining power. The confirmation test identifies both regression and ANN techniques are the most effective tools to evaluate machinability characteristics of HCWCI. Further, the CBN cutting tool exhibits excellent performance in machining of HCWCI. © 2014, The Indian Institute of Metals - IIM.
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    Buckling and vibration behavior of a non-uniformly heated isotropic cylindrical panel
    (Techno-Press, 2016) Bhagat, V.S.; Jeyaraj, P.; Murigendrappa, S.M.
    This study attempts to address the buckling and free vibration characteristics of an isotropic cylindrical panel subjected to non-uniform temperature rise using numerical approach. Finite element analysis has been used in the present study. The approach involves three parts, in the first part non-uniform temperature field is obtained using heat transfer analysis, in the second part, the stress field is computed under the thermal load using static condition and, the last part, the buckling and pre-stressed modal analysis are carried out to compute critical buckling temperature as well as natural frequencies and associated mode shapes. In the present study, the effect of non-uniform temperature field, heat sink temperatures and in-plane boundary constraints are considered. The relation between buckling temperature under uniform and non-uniform temperature fields has been established. Results revealed that decrease (Case (ii)) type temperature variation field influences the fundamental buckling mode shape significantly. Further, it is observed that natural frequencies under free vibration state, decreases as temperature increases. However, the reduction is significantly higher for the lowest natural frequency. It is also found that, with an increase in temperature, nodal and anti-nodal positions of free vibration mode shapes is shifting towards the location where the intensity of the heat source is high and structural stiffness is low. © © 2016 Techno-Press, Ltd.
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    Determination of coupling factors for adhesive-bonded plates
    (Asian Research Publishing Network arpn@arpnjournals.com, 2016) Pankaj, A.C.; Murigendrappa, S.M.
    Adhesive bonding has gained importance in structural bonding in aircraft industry as an alternative method of joining materials together over the more conventional joining methods. It is gaining interest due to the increasing demand for joining similar or dissimilar structural components, mostly within the framework of designing light weight structures. In this present study, a finite element model of a structure, consisting of two Acrylic/Perspex plates joined by an adhesive has been modeled using ANSYS software. Comparisons have been made for the computed coupling factors and velocity responses for the adhesive bonded plates using finite element method and analytical wave approach of the same plates for a line junction at the joint. The results obtained from the studies signify the importance of modeling of adhesive joints in computation of the coupling factors and its further use in computation of energies and velocity responses using statistical energy approach as compared to the values obtained using analytical wave approach for a continuous line junction. Coupling factors have been computed from the velocity responses for the adhesive bonded plates using finite element method and compared with the values obtained from the analytical wave approach for the same plates with a line junction at the joint. © 2006-2016 Asian Research Publishing Network (ARPN).
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    Stability enhancement of a powered two wheeler vehicle under curve negotiation
    (IAEME Publication, 2016) Nayak, A.; Ashwin, H.S.; Murigendrappa, S.M.
    During cornering of a two wheeler under dynamic conditions when the vehicle is steered to the left or right, the axis of the wheels and other rotating parts undergoes precession along with spinning which produces a gyroscopic couple. Due to the action of these moments on the vehicles along with the centrifugal forces and gravity acting on it, the vehicle may either skid or overturn depending on the angle of tilt, velocity of the motorcycle, radius of the curve & mass of the vehicle. The main objective of this work is to ensure the safe negotiation of the turn and to prevent accidents by establishing a harmonious relationship between the effecting parameters. A device was developed to act as a feedback control system; taking the inputs from a IMU sensor, predict the equilibrium conditions and thereby control the dynamic parameters of the 2 wheeler in order to enable it negotiate the curve safely. © IAEME Publication.
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    Buckling of non-uniformly heated isotropic beam: Experimental and theoretical investigations
    (Elsevier Ltd, 2016) George, N.; Jeyaraj, P.; Murigendrappa, S.M.
    Influence of non-uniform heating on critical buckling temperature of an aluminium beam has been investigated experimentally with the help of a novel experimental set-up developed in-house. Non-linear finite element analysis, considering the initial geometric imperfection, has been carried out to compare the experimentally obtained typical load-deflection curve. The linear critical buckling temperature predicted numerically are validated with analytical solutions. Experimental results revealed that critical buckling temperature of the non-uniformly heated beam greatly differs from the uniformly heated beam. It is also observed that the location of heat source and resulting non-uniform temperature variation influences the critical buckling temperature significantly. © 2016 Elsevier Ltd
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    Buckling and dynamic characteristics of a laminated cylindrical panel under non-uniform thermal load
    (Techno Press technop2@chollian.net, 2016) Bhagat, V.; Jeyaraj, J.; Murigendrappa, S.M.
    Buckling and free vibration behavior of a laminated cylindrical panel exposed to non-uniform thermal load is addressed in the present study. The approach comprises of three portions, in the first portion, heat transfer analysis is carried out to compute the non-uniform temperature fields, whereas second portion consists of static analysis wherein stress fields due to thermal load is obtained, and the last portion consists of buckling and prestressed modal analyzes to capture the critical buckling temperature as well as first five natural frequencies and associated mode shapes. Finite element is used to perform the numerical investigation. The detailed parametric study is carried out to analyze the effect of nature of temperature variation across the panel, laminate sequence and structural boundary constraints on the buckling and free vibration behavior. The relation between the buckling temperature of the panel under uniform temperature field and non-uniform temperature field is established using magnification factor. Among four cases considered in this study for position of heat sources, highest magnification factor is observed at the forefront curved edge of the panel where heat source is placed. It is also observed that thermal buckling strength and buckling mode shapes are highly sensitive to nature of temperature field and the effect is significant for the above-mentioned temperature field. Furthermore, it is also observed that the panel with antisymmetric laminate has better buckling strength. Free vibration frequencies and the associated mode shapes are significantly influenced by the non-uniform temperature variations. © 2016 Techno-Press, Ltd.
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    A Bottom-Up Optimization Approach for Friction Stir Welding Parameters of Dissimilar AA2024-T351 and AA7075-T651 Alloys
    (Springer New York LLC barbara.b.bertram@gsk.com, 2017) Anil Kumar, K.S.; Murigendrappa, S.M.; Kumar, H.
    In the present study, optimum friction stir weld parameters such as plunge depth, tool rotation speed and traverse speed for butt weld of dissimilar aluminum alloy plates, typically 2024-T351 and 7075-T651, are investigated using a bottom-up approach. In the approach, optimum FSW parameters are achieved by varying any one parameter for every trial while remaining parameters are kept constant. The specimens are extracted from the friction stir-welded plates for studying the tensile, hardness and microstructure properties. Optimum friction stir weld individual parameters are selected based on the highest ultimate tensile strength of the friction stir-welded butt joint specimens produced by varying in each case one parameter and keeping the other two constant. The microstructure samples were investigated for presence of defects, grain refinement at the weld nugget (WN), bonding between the two materials and interface of WN, TMAZ (thermomechanically affected zone) of both advancing and retreating sides of the dissimilar joints using optical microscopy and scanning electron microscopy analyses. In the experimental investigations, the optimum FSW parameters such as plunge depth, 6.2 mm, rotation speed, 650 rpm and traverse speed of 150 mm/min result in ultimate tensile strength, 435 MPa, yield strength, 290 MPa, weld joint efficiency, 92% and maximum elongation, 13%. The microstructure of optimized sample in the WN region revealed alternate lamellae material flow pattern with better metallurgical properties, defect free and very fine equiaxed grain size of about 3-5 µm. © 2017, ASM International.