High Speed Railway Vehicle Comfort. The Influence of Pneumatic Flow Restrictor Diameter, Rail Irregularities, Speed and Structural Damping and Stiffness

The work presented in this paper assesses the influence of flow restrictor diameter, rail irregularities, speed, structural damping, and structural stiffness on comfort indexes. The pneumatic suspension models that the authors have developed are succinctly abridged, and on board tests that support the models are shown. The models are used in conjunction with synthesized rail profiles in order to determine comfort indexes and assess the influence of suspension parameters. The results suggest the use of variable diameter configurations. However, comfort is also affected by the structural response of the vehicle frame. Low stiffness and low structural damping greatly reduce comfort. To assess the influence of structural damping and stiffness, the frame is represented as a uniform Euler-Bernoulli beam with complex elastic modulus and is analyzed in the frequency domain. The increase of comfort indexes as a consequence of stiffness reduction can be mitigated with the use of viscoelastic materials to increase structural damping.