Rail vehicle dynamic response to a nonlinear physical ‘in-service’ model of its secondary suspension hydraulic dampers

A full nonlinear physical ‘in-service’ model was built for a rail vehicle secondary suspension
hydraulic damper with shim-pack-type valves. In the modelling process, a shim pack
deflection theory with an equivalent-pressure correction factor was proposed, and a Finite
Element Analysis (FEA) approach was applied. Bench test results validated the damper
model over its full velocity range and thus also proved that the proposed shim pack deflection
theory and the FEA-based parameter identification approach are effective. The validated
full damper model was subsequently incorporated into a detailed vehicle
dynamics simulation to study how its key in-service parameter variations influence the
secondary-suspension-related vehicle system dynamics. The obtained nonlinear physical
in-service damper model and the vehicle dynamic response characteristics in this study
could be used in the product design optimization and nonlinear optimal specifications of
high-speed rail hydraulic dampers.