Reduction of continuous system of railway vehicle bogie to multibody one with low number DOF

Modelling huge system consisting of many subsystems and modelled by the professional software package it is useful to reduce degrees of freedom (DOF) of individual subsystem while the chosen eigenfrequencies and eigenvectors are preserved. It can be performed by means of modal condensation [1], [2] under the additional conditions. These conditions are posed on the total mass, moment of inertia and position of the gravity centre.