Stability behaviour of a basic magnetic track brake model: Influences of system parameters and motion-induced eddy currents

Abstract

Insights into the vibrational behaviour of emergency braking systems of railway vehicles, such as the electromagnetic track brake, are indispensable for short stopping distances and safe operation. Moreover, they are fundamental for the development of lightweight railway vehicles. Hence, the nonlinear stability behaviour of the electromagnetic track brake is examined within this paper by applying bifurcation analysis and numerical continuation methods to a newly developed minimal model. The proposed electromagnetic-mechanical model accounts for a segmented brake magnet, incorporating the frictional contact of individual brake elements and a velocity-dependent attraction force resulting from motion-induced eddy currents, revealed by experiments. Two super-critical Hopf bifurcations give rise to periodic orbits of pure slip motions for varying vehicle velocities, compliant with observations from measurements. Further, a second branch of stable periodic orbits with large amplitudes at a similar oscillatory frequency exhibiting stick-slip motions is found. By modifying the friction characteristics, the coexisting periodic attractors converge, resulting in a branching point that marks the onset of a parameter region where only large-amplitude periodic orbits with stick-slip motions are stable. Influences of main design and environmental parameters are studied.