Study on effect of unbalanced mass in lateral rotor vibration of rotating machinery in the 8-DOF model based on finite element method

In this paper, applying Lagrange method, the governing coupled partial differential equations of motion for the 8-DOFs model of rotor dynamics based on the finite element method considering the effect of all mass elements including shaft and disk mass element and bending effects of the rotor shaft in conjecture with the stiffness and damping coefficients of the bearings and static and dynamic unbalanced masses are all included to analyze the lateral rotor vibrations. Using a computer code written in the environment of MATLAB mathematical software, based on the rotor 8-DOF model vibration amplitudes of the rotor considering the unbalanced mass are calculated. The effects of variation of different parameters including the stiffness and damping coefficients of rotor bearings, rotational speed of the shaft, bending rigidity of the rotor shaft, density of rotor the shaft material, outer and inner radius and as well length of the rotor shaft in the lateral vibration of rotor dynamics are all investigated.