International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 02 Issue: 09 | Dec-2015 www.irjet.net p-ISSN: 2395-0072 © 2015, IRJET ISO 9001:2008 Certified Journal Page 762 STUDY OF ROTOR BEARING SYSTEM- A REVIEW Prashant Verma 1 , Sankha Bhaduri 2 1 P.G. Research Scholar, Dept. of Mechanical Engineering, BIT Mesra, Jharkhand, India 2 Assistant Professor, Dept. of Mechanical Engineering, BIT Mesra, Jharkhand, India -------------------------------------------------------------***------------------------------------------------------------- Abstract - Rotating machines are extensively used in mechanical engineering applications. Rotor- disc- bearing assembly is one of the most interesting fields of study in the research area. The unbalance excitation of rotor, stability analysis of rotor or vibration control of rotor receives significant research importance over the decades. The aim of this study is to collect different research paper on the rotor-bearing system. The different improved mathematical modeling of rotor bearing system and the application of finite element model in this field improves the accuracy of the analysis of rotor bearing system. This review paper attempts to collect researchers’ different contributions on this field. Key words: Rotor Bearing, Finite Element Method, Campbell diagram, Natural Frequency. INTRODUCTION Rotor dynamics is specialized branch in which study includes the lateral and torsional vibration of rotating shaft. The basic component of rotor dynamics is shaft or rotor. It also includes disc and the bearings which supports the rotor. As the rotating speed increases the amplitude of vibration also increases and it passes through a speed where it matches with the natural frequency that is called critical speed. Rotating part produce the vibration depending upon the mechanism used and if any fault is present in machine then it increases the vibration. Analysis in rotating system involves study of critical speed, unbalance loads, deflection of shaft. Bearing also plays an important role in controlling the vibration in which it acts as a damper. The stability of rotor and critical speed is mainly controlled by the stiffness properties and peak amplitude response of the bearing. Analysis of rotor dynamic is basically of three types: Modal Analysis: In this study analysis is done for the effect of speed on frequency from zero rpm to the maximum velocity, these natural frequencies determined to avoid excitation at critical speed Harmonic Analysis: In this analysis a range of frequencies is set to determine the response of system at different rotating speed and excitation forces. Static and transient response: In this analysis loads on structure, joints and bearings are determined and this is done by applying fixed velocity to initial condition or transient dynamic simulation. Many researchers studied the rotor dynamics from mid twenty century and concluded that theoretically it is difficult to find the real dynamics of rotating machine, therefore to get the natural frequencies, experiments done by making models and analyzed them through another approach like Lumped parameters models, Rayleigh-Ritz method and Finite Element Method (FEM). Then researchers founded that Finite Element Method was the best modal for finding the natural frequencies. The present study is aiming to discuss the different types of research in the field of rotor dynamics. The introduction of different mathematical models or application of finite element technique will be discussed in this study. This review paper will try to collect different papers on the rotor dynamics. LITERATURE REVIEW Nelson and McVaugh [1] developed finite element model for rotor-bearing system which consist of rigid disks, rotor with distributed mass and variable cross-section and discrete bearings. In their finite element rotor model rotary inertia, gyroscopic moments and axial load are included. The detailed equations for the elements are expressed both in the fixed and rotating reference frame. Khulief and Mohiuddin [2] presented a finite element elastodynamic model of rotor bearing system which accounted for gyroscopic moment and anisotropic bearings. Two modal truncation schemes were introduced for planar (undamped) mode and complex (damped) mode. For both modal reduction schemes modal characteristics and dynamic responses of two rotor system