Assessing the validity of torsional motion on dynamic analysis of rotor bearing system using finite element

The rotor-bearing system has been used extensively in machinery industry. The precise prediction of dynamic behaviour is vital for preventing any catastrophic occurrence from happening due to a vibration phenomenon. This work is based on Nelson’s shaft model that contains two translation components and three rotary inertia components. Besides the bending and transverse shear deformation elements, additional torsional motions are included in the model. The objective is to investigate the effect of different level stiffness of the isotropic bearing and the torsional element towards the whirling phenomenon. The Campbell diagram obtained by applying Bolotin method to the finite element equation of motion is employed here to predict the whirling frequency. It was discovered that the torsional motion has different substantial effect on whirling speed for various levels of bearing stiffness. The highest impact of 8.57% difference can be seen for soft bearing that occurs in the 1st mode corresponds to forward frequency direction