Modal Response of a 4-DOF Cantilever Rotor System with 2 Bearing Support Under Rotor Rub Impact with Unbalance

This paper studies the modal response of rotor systems such as turbine engines during rubbing due to unbalance. Rubbing in rotor introduces nonlinearity in the system which leads to phenomena such as rotor stiffening. Experimentation for such cases bears huge cost; hence, nowadays simulation results are widely acceptable. In this paper, a cantilever rotor with 2 bearing support model has been studied for unbalance due to rub in the rotor. Response of such system has been studied on MATLAB. The results reveal the dependence of natural frequency on additional parameter, modal amplitude, which usually is dependent on rotor spin speed in case of linear systems. Effect of parameters such as external damping, stiffness, friction coefficient between the rotor and stator on the modal response of such system has also been presented. The modal response clearly brings out the nonlinear behavior of the rotor system.