On Continuous Subsystem Modelling in the Dynamic Interaction Problem of a Train-Track-System

SUMMARY The paper deals with the dynamics of a periodic structure by means of which such a mechanical system as a railway track can be modelled. The structure considered consists of an infinite Bernoulli-Euler beam resting on periodically spaced spring-damper-mass elements. At first, the case of free wave propagation in a pure elastic structure is considered. Then the steady-state system dynamic response to a moving harmonic force is studied. In both cases a procerure is used which bases on Floquet's theorem. The analysis of dispersion relations makes it possible to determine passing and stopping bands and the eigenforms corresponding to cut-off frequencies. A simple way of calculating critical velocities and frequencies of the load is proposed ana a physical explanation for the increase of wave amplitudes is given.