Investigation of the dynamics of railway bogies subjected to traction/braking torque

"The limitations of current simulation packages in addressing the true longitudinal behaviour of railway bogie dynamics during braking/traction has prompted the development of a Rail Bogie Dynamics (RBD) program in this thesis. The RBD program offers novel features for the calculation of the speed profile as a function of the brake torque as well as explicitly determining wheelset angular velocity. With such capability, the speed profile is no longer treated as an input calculated as a priori as required by most of the current simulation systems. The RBD program has been developed using a formulation that includes the wheelset pitch degree of freedom explicitly with a coordinate reference system that is fixed in space and time. The formulation has made the simulation of the bogie dynamics during braking/traction possible in a natural way using the brake/traction torque as the input and the resulting speed profile as the output without any need for working out the speed profile as a priori. Consequently, severe dynamics during braking such as the wheelset skid and the onset of wheel climb derailment can be modelled and critical parameters investigated using the RBD program. The RBD program has been validated, where possible, through a series of simulations using a commercial software package (VAMPIRE). For cases which cannot be simulated by VAMPIRE such as the wheelset skid, a novel experimental program has been designed and commissioned in the Heavy Testing Laboratory of the Central Queensland University as reported in this thesis. One of the possible applications of the RBD program in examining the effect of asymmetric brake shoe force in bogies equipped with one-side push brake shoe arrangement is illustrated in this thesis. It is believed that the model and RBD program will have significant benefit in understanding the true longitudinal behaviour of wagons in suburban passenger trains that operate under braking/ traction torques for most of their travel. Similar studies will also be useful to freight train wagon dynamics during entry and exit of speed restriction zones and tight curves." -- abstract.