Waves, modes and properties with a major impact on dynamic pantograph-catenary interaction

Abstract

Understanding the dynamic behavior of the pantograph-catenary system is crucial for design improvement, but many factors inuence the contact force, which is the main design objective. To give a proper un-derstanding of dynamic characteristics, the paper uses a combination of mass drop tests on a catenary, analytic models and parametric _nite element model simulations allowing a ne analysis of the inuence of train speed. The _rst contributor to contact force variations is the geometry of the catenary under gravity loading. This parameter is however shown to be insu_cient to explain higher frequency e_ects. The second contributor is the propagation of waves in the contact and messenger wires. The inuence of wave dis-persion is _rst demonstrated, which emphasizes the importance of considering the bending sti_ness. Wave compensation by droppers and reections at the mast are then shown to be important. Characteristic times associated with wave group velocities are _nally used to explain the series of harmonic contributions visible in spectra in the catenary and pantograph frames. Finally, modes are shown to play a role particularly when their frequencies coincide with other contributions. The notion of mode groups, associated wave velocities and relevant design variables are discussed. Several observations pave the way for future work on catenary design.