The main approach of this thesis was to develop a mathematical model that represents a rotary machine. Experimental data was used to define a finite element model (FEM). In order to obtain the experimental data, the rotary machine had to be balanced. An impact hammer test made it possible to obtain frequency response functions (FRF). The frequency response functions were curvefitted in order to obtain the mode shapes and natural frequencies. Mathematical models have been created with ABAQUS and Matlab. For the Matlab Model the assumption has been made that the rotor machine consists of a specific number of beam elements. The FEM matrices have been reduced with the Guyan Reduction Method to coincide with the DOFs of the experiment. Applying the method of the least square to an Error Function made it possible to obtain new values for the stiffness and damping of the bearings (). This made it possible to update the mathematical model. By applying the Model Assumption Criterion the theoretical model and those detected from the experimental measurement could be validated. The correlation for Mode Shapes 1 could be improved from 0.6647 to 0.8186 and for Mode Shape 2 from 0.0209 to 0.4208. Therefore, the created method could be proven to work. Additionally the whole theory has been validated with a very simplified model.