NONLINEAR DYNAMIC RESPONSE ANALYSIS OF HIGH- SPEED CYLINDRICAL ROLLER BEARINGS

Abstract

Bearings are the most critical and extensively used components in the industry application. A bearing has two main purposes: transmitting force and allowing a relative motion among machine elements. There is a critical need to improve the health monitoring of the performance of the bearing to avoid catastrophic failure. Out of various bearings, rolling element bearings are used in various applications, starting from heavy load and high temperature to the dusty environment to various life-critical applications. Due to low heat generation, lesser sensitivity to load variation, and higher stiffness value than conventional hydrodynamic bearing, rolling element bearings are widely used. This work attempts to analyze the nonlinear vibration response of the high-speed cylindrical roller bearings under balanced and unbalanced rotor conditions and due to healthy and defective rolling elements. The complexity involves in the system due to nonlinear stiffness and damping present in the contact area and also due to various parametric and nonparametric effects. A spring-mass model with nonlinear stiffness and damping is formulated and all the parameters responsible for the producing vibration in the system are incorporated to study the dynamic behavior of the rotor-bearing model. The set of nonlinear differential equations are solved using the fourth-order Runge–Kutta method to predict the characteristics of the discrete spectra and analyze the stability of the system using various motion analyzer such as orbit plots, phase portraits, Poincaré maps, and FFT plots. The obtained response showed the existence of several routes to chaos regime with speed and clearance variations for balanced and unbalanced rotor conditions for healthy and defective rolling elements. A pattern of the interaction between rotational and variable compliance vibration is also observed with speed variations. An experimental setup has been developed to create a database of dynamic responses of cylindrical roller bearings. The experimental studies have been conducted for a speed range up to 40 Hz with the same controlling parameters for both balanced and unbalanced rotor conditions. Four bearing cases have been analyzed as healthy bearing, bearing with outer race defect, inner race defect and roller defect. Experimental phase portraits and orbit plots have been investigated with time and frequency responses. Experimental verifications have been performed to justify the proposed numerical simulation results for various bearing conditions supported under balanced and unbalanced rotor conditions.