NON STATIONARY RESPONSE OF A TWO DIMENSIONAL VEHICLE ON A RANDOM TRACK

Abstract

A railway wagon is mathematically modeled as a vehicle with linear stiffness and damping. The vehicle has heave and pitch degrees of freedom and moves with constant acceleration over a prepared railway track. The track is characterized by a given power spectrum in space domain. The input base excitation to the vehicle is simulated digitally using the given power spectrum. Various cases of vehicle-cargo mass system are considered. The vehicle response for -displacement is determined numerically. It is found that greater eccentricity of the cargo mass leads to greater vehicle response. This is specially true for pitch response. Base length variations show that the vehicle response in pitch is changed significantly for small base length. The heave response does not change significantly. changes in vehicle response in absolute values due to change in stiffness has been found marginal for heave response as well as in pitch response. Damping has a profound effect on vehicle displacement response both in pitch and heave modes. It is virtually a parameter which controls the vehicle dynamic stability. The changes in constant acceleration affects the vehicle response. The response builds up fast with increase in acceleration. It is found that acceleration response in heave and pitch mode is not important for heavy vehicles such as railway wagon.