Modelling damping effects in vehicle-track interaction

It is a well-known fact that railway activities inevitably generate vibrations in the track structure and the sub-ground, which may have negative effects on the surrounding environment and constructions. Because of the very serious effects that unwanted vibrations can have on dynamic system, it is essential that vibration analysis be carried out as an inherent part of their design; when necessary modifications can easily be made to eliminate vibration or at least to reduce it as much as possible. It is usually much easier to analyze and modify a structure with undesirable vibration characteristics after it has been built. However, it is sometimes necessary to be able to reduce the vibration of existing structures brought about by inadequate initial design, by changing the function of the structure or by changing the environmental conditions, and therefore techniques for the analysis of structural vibration should be applicable to existing structures as well as to those in the design stage. In general present-day structures often contain high energy sources which create intense vibration excitation problems. The level of vibration in a structure can be attenuated by reducing either the excitation, or the response of the structure to that excitation or both. It is sometimes possible, in the design stage, to reduce the exciting force or motion by changing the equipment responsible, by relocating it within the structure or by isolating it from the structure so that the generated vibration is not transmitted to the support. In this paper we analyze the effect of the vertical damper on the global system vehicle-wheel-track when, load and empty conditions appear in vehicle. A final comparison is carried-out among damping and undamping vehicle systems.