Vibration behavior study of a rotor using Jeffcott's 8 DOF model and comparing with the experimental test

Analytical, numerical, and experimental solution of the rotating system in the stages of design, construction, and operation is important in order to prevent resonance phenomenon. In this research, the numerical and experimental analysis of a rotor is studied using Jeffcatt’s 8 DOF model. The equations of motion by considering the gyroscopic effects and the mass of the bearings are formulated using the Lagrange method. After introducing a model of the system, the terms of potential, kinetic, and dissipation energy are obtained according to the boundary conditions. Then, by placing the system parameters, the natural frequencies of the system and the Campbell diagram have been obtained in order to predict the critical speeds. Validation of the presented model has been done by comparing with the results of Finite Element Solution (ANSYS) and approximate solution, and also percentage error of the first critical frequency compared to the experimental value is 15%. Then, the effect of changing the position of the disk from the first bearing on the natural frequencies of the system is studied. In the end, the system's frequency response is presented at the different unbalanced distances and the position of the disk. Observations show that changes in unbalanced distance and position of the disk can affect the frequency and resonance peak of the system.