This paper provides an insight into vibration theory and its parts related to rotodynamics such as components of simple damped vibration systems (mass, spring and damper). Also described are the ways in which programs for solving rotodynamic models by the finite element method function and the ways of determining the mesh, that is, the division of models into elements with the help of St. Venant's principle. The basis for the simulation described in this paper was laid by H. Jeffcott in 1919, and his academic life and his contribution to science are briefly described. For the simulation, an asymmetric rotor with three disks was modeled, each of the disks is of different dimensions and characteristics. The simulation was done in the Ansys program in which the first 6 natural frequencies of a 3-disk rotor were found, and then the forced rotor response at the rotor center point was determined for frequencies from 0 to 500 Hz for cases of phase and antiphase imbalance of 200 g mm. In addition to the forced response, vibration forms are shown for each case. The natural frequencies were found with the 3D model while the forced response and vibration forms were found using the 1D model.