On the dynamics of a four-axle railway vehicle with dry friction yaw damping

In the paper, we investigate numerically the influence of dry friction yaw damping on the dynamics of a railway vehicle with four wheel sets. The speed of the vehicle is the control parameter. The stick/slip mechanism is considered. The first bifurcation points are found. The results demonstrate the influence of the stick/slip on the dynamics of the vehicle. For speeds above the critical speed, it is found that the symmetry of the dynamical problem is broken and erratic - possibly chaotic - motions appear. The paper ends with an investigation of the sensitivity of the results to different solvers from Matlab. It is found that ODE15s needs the largest computation time and it is more accurate than ODE45 with the same tolerances. ODE45 is satisfactory. It is fast, accurate and shows the same erratic features as ODE15s does. Dry friction damping is still used in almost all freight wagons in the world due to the low cost of the elements.