Journal Articles
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Item Friction-free permanent magnet bearings for rotating shafts: A comprehensive review(Electromagnetics Academy, 2020) Bekinal, S.I.; Doddamani, M.This article presents a comprehensive review of modeling, analysis, and development of permanent magnet bearings (PMB) for rotating shafts. The different configurations of PMB are highlighted with relevant approaches to estimate their features. The progress in mathematical approaches adopted and optimization of the static and dynamic bearing characteristics in terms of accuracy are discussed in depth. Further, key developments on instability issues and their realization in combination with other bearings for rotors stability in low and high-speed applications are reviewed. Finally, concluding remarks on key aspects to be followed in the design and development of PMB are presented. © 2020, Electromagnetics Academy. All rights reserved.Item A Review of Superconducting Magnetic Bearings and Their Application(Institute of Electrical and Electronics Engineers Inc., 2022) Supreeth, D.K.; Bekinal, S.I.; Shivamurthy, S.R.; Doddamani, M.Magnetic bearings are being researched for high-speed applications, such as flywheel energy storage devices, to eliminate friction losses. As per Earnshaw's theorem, stable levitation cannot be achieved for a static passive magnetic bearing system. Fully passive stable levitation can be achieved with the help of superconducting magnetic bearings (SMB). This article provides an in-depth review of the modeling, analysis, and development of SMB. The different SMB configurations are highlighted, together with essential methodologies for estimating and improving their performance. The advancements in mathematical models used and the optimization of bearing characteristics are thoroughly discussed. Further, key developments in the application of SMB in flywheel energy storage systems are also reviewed. © 2002-2011 IEEE.Item Utilization of low computational cost two dimensional analytical equations in optimization of multi rings permanent magnet thrust bearings(Electromagnetics Academy chew@jpier.org Suite 207777 Concord Avenue Cambridge, MA 02138, USA 02138 Massachusetts, 2017) Bekinal, S.I.; Doddamani, M.; Dravid, N.D.Replacement of conventional bearings by passive magnetic bearings for high-speed applications, in terms of their performance will be effective, if the design is carried out by optimizing the geometrical dimensions in the given control volume. Present work deals with modification and utilization of two-dimensional (2D) analytical equations in optimization of multi rings permanent magnet (PM) thrust bearing configurations. Conventional and rotational magnetized direction (RMD) configurations are selected in optimizing the design variables for maximum bearing characteristics in a given volume with a constant aspect ratio. The design variables chosen for optimization are axial offset of rotor, number of rings, radial air thickness and inner diameter of the rotor and stator PM rings. MATLAB codes for solving 2D equations are developed in optimizing configuration variables. Further, optimized parameter values of the two configurations are compared. Finally, optimized results obtained using 2D and three-dimensional (3D) equations for the conventional configuration with same aspect ratio are compared, and conclusions are presented. © 2017, Electromagnetics Academy. All rights reserved.Item Optimization of Axially Magnetized Stack Structured Permanent Magnet Thrust Bearing Using Three- Dimensional Mathematical Model(American Society of Mechanical Engineers (ASME) infocentral@asme.org, 2017) Bekinal, S.I.; Doddamani, M.; Jana, S.This work deals with optimization of axially magnetized stack structured permanent magnet (PM) thrust bearing using generalized three-dimensional (3D) mathematical model having "n" number of ring pairs. The stack structured PM thrust bearing is optimized for the maximum axial force and stiffness in a given cylindrical volume. MATLAB codes are written to solve the developed equations for optimization of geometrical parameters (axial offset, number of ring pairs, air gap, and inner radius of inner and outer rings). Further, the results of proposed optimization method are validated using finite element analysis (FEA) and further, generalized by establishing the relationship between optimal design variables and air gap pertaining to cylindrical volume constraint of bearing's outer diameter. Effectiveness of the proposed method is demonstrated by optimizing PM thrust bearing in a given cylindrical volume. Mathematical model with optimized geometrical parameters dealt in the present work helps the designer in developing PM thrust bearings effectively and efficiently for variety of applications. © 2017 by ASME.Item A Pragmatic Optimization of Axial Stack-Radial Passive Magnetic Bearings(American Society of Mechanical Engineers (ASME) infocentral@asme.org, 2018) Lijesh, L.; Doddamani, M.; Bekinal, S.I.Passive magnetic bearing's (PMB) adaptability for both lower and higher speed applications demands detailed and critical analysis of design, performance optimization, and manufacturability. Optimization techniques for stacked PMB published in recent past are less accurate with respect to complete optimum solution. In this context, the present work deals with a pragmatic optimization of axially stacked PMBs for the maximum radial load using three-dimensional (3D) equations. Optimization for three different PMB configurations, monolithic, conventional, and rotational magnetized direction (RMD), is presented based on the constraints, constants, and bounds of the dimensions obtained from published literature. Further, to assist the designers, equations to estimate the mean radius and clearance being crucial parameters are provided for the given axial length and outer radius of the stator with the objective of achieving maximum load-carrying capacity. A comparison of the load-carrying capacity of conventional stacked PMB using the proposed equation with the equation provided in literature is compared. Finally, effectiveness of the proposed pragmatic optimization technique is demonstrated by analyzing three examples with reference to available literature. © 2018 by ASME.Item Multi-objective optimization of stacked radial passive magnetic bearing(SAGE Publications Ltd info@sagepub.co.uk, 2018) Lijesh, K.P.; Doddamani, M.; Bekinal, S.I.; Muzakkir, S.M.Modeling, design, and optimization for performances of passive magnetic bearings (PMBs) are indispensable, as they deliver lubrication free, friction less, zero wear, and maintenance-free operations. However, single-layer PMBs has lower load-carrying capacity and stiffness necessitating development of stacked structure PMBs for maximum load and stiffness. Present work is focused on multi-objective optimization of radial PMBs to achieve maximum load-carrying capacity and stiffness in a given volume. Three-dimensional Coulombian equations are utilized for estimating load and stiffness of stacked radial PMBs. Constraints, constants, and bounds for the optimization are extracted from the available literature. Optimization is performed for force and stiffness maximization in the obtained bounds with three PMB configurations, namely (i) mono-layer, (ii) conventional (back to back), and (iii) rotational magnetized direction. The optimum dimensions required for achieving maximum load without compromising stiffness for all three configurations is investigated. For designers ease, equations to estimate the optimized values of load, stiffness, and stacked PMB variables in terms of single-layer PMB are proposed. Finally, the effectiveness of the proposed method is demonstrated by considering the PMB dimensions from the available literature. © IMechE 2017.Item Generalized optimization procedure for rotational magnetized direction permanent magnet thrust bearing configuration(SAGE Publications Ltd info@sagepub.co.uk, 2019) Bekinal, S.I.; Doddamani, M.; Vanarotti, M.; Jana, S.Optimization of rotational magnetized direction permanent magnet thrust bearing configuration is carried out using generalized three-dimensional mathematical model. The bearing features namely axial force and stiffness are maximized using in-house developed mathematical expressions solved using MATLAB. The design variables selected for the optimization are axial offset, number of ring pairs, air gap and inner radius of inner and outer rings. The maximized axial force values of the optimized configuration are validated with the finite element analysis results. To overcome the high computational cost associated with three-dimensional equations, generalized method of optimization is sucessfully demonstrated using plots representing variation of optimal design variables as a function of air gap with respect to bearing’s outer diameter. Simple and useful method of using the generalized plots for the process of optimization is presented by dimension optimization of representative bearing configuration with a particular aspect ratio. The proposed optimization using mathematical model and generalized approach assists designer in selecting optimized geometrical parameters of rotational magnetized direction thrust bearing configurations easily for variety of high-speed applications. © IMechE 2018.Item Improvement in the design calculations of multi-ring permanent magnet thrust bearing(Electromagnetics Academy, 2020) Bekinal, S.I.; Doddamani, M.This article presents the design and optimization of multi-ring permanent magnet thrust bearing (PMTB) with an axial air gap between successive axial stacks. Larger air gap due to the inclusion of conductive materials needs to be critically analysed in permanent magnet bearings with eddy current damper. High conductivity materials can be filled in an axial air gap instead of a radial air gap to increase the required amount of damping. Three-dimensional (3D) mathematical model for load-carrying capacity for the said configuration is presented using the Coulombain model. The significance of an axial air gap between successive ring pairs in the configuration concerning maximization in the bearing characteristics is presented. Variables such as the number of axial stacks, an axial air gap between the successive rings, an inside radius of rotor ring magnets, and an inside radius of stator ring magnets are optimized at different air gap values for maximizing the load-carrying capacity and stiffness. A significant increase in the values of bearing characteristics is observed in the optimized configuration as compared to bearing with a single permanent magnet ring pair. Optimized PMTB with comparable load carrying capacity and stiffness values can be used to replace conventional bearings used in high-speed applications to improve system efficiency. © 2020, Electromagnetics Academy. All rights reserved.Item Optimum Design Methodology for Axially Polarized Multi-Ring Radial and Thrust Permanent Magnet Bearings(Electromagnetics Academy, 2020) Bekinal, S.I.; Doddamani, M.This article deals with the generalized procedure of designing and optimizing multi-ring radial and thrust permanent magnet bearings (PMBs) with an axial air gap for maximum force andstiffness per volume of the magnet. Initially, the procedure of determining optimized design variables inboth the configurations is presented using the MATLAB codes written for solving the three dimensional(3D) equations of force and stiffness in PMB having ‘n’ number of rings on the stator and rotor. Themaximized results of the forces in both radial and thrust multi-ring PMBs are validated with the valuesobtained using finite element analysis (FEA). Then, the correlation between the optimized parametersand the air gap is obtained, and curve fit equations for the same are proposed in terms of stator outerdiameter. Further, curve fit equations establishing the relationship between the maximized bearingfeatures, and the aspect ratio (L/D4) of the bearing are expressed for different values of air gap inboth the radial and thrust bearings. Finally, the generalized method of designing and optimizing themulti-ring PMB is demonstrated with a specific application. A designer can use the presented curvefit equations for optimizing design variables and calculating maximized bearing features in multi-ringradial and thrust PMBs easily just by knowing the bearing features for a single ring pair. © 2020. All Rights Reserved.Item Analysis of novel eddy current damper for multi-ring permanent magnet thrust bearing(Electromagnetics Academy, 2021) Deshwal, D.; Bekinal, S.I.; Doddamani, M.—This paper deals with analyzing a novel eddy current damper for an axially magnetized multi-ring permanent magnet thrust bearing (MPMTB). Initially, the bearing is optimized for maximum axial force by selecting three general parameters (air gap, outer diameter of stator, and length) using a generalized optimization procedure. Then, the axial force of an optimized bearing is validated with the mathematical model results. Finally, the novel and conventional eddy current dampers (ECDs) for an optimized MPMTB are analyzed for damping forces and coefficients using three-dimensional (3D) finite element transient analysis in ANSYS. Based on the analysis results, the proposed novel structure could be selected to replace the conventional one for providing damping to MPMTB effectively without affecting the radial air gap between the rotor and stator rings. © 2021, Electromagnetics Academy. All rights reserved.