Inertance-Integrated Primary Suspension Optimisation on an Industrial Railway Vehicle Model

Improving the track friendliness of a railway vehicle is highly beneficial to the rail industry, as it substantially increases its cost effectiveness. Rail surface damage under curving conditions can be reduced by using vehicles with a reduced Primary Yaw Stiffness (PYS); however, a lower PYS often leads to a reduction in high-speed stability and can negatively impact ride comfort. Previous studies have suggested that this trade-off, between track friendliness and passenger comfort, can be successfully improved by using an inerter in the primary suspension; however, these studies used simplified two-axle vehicles and simplified contact models, and track inputs. Considering a more realistic four-axle passenger vehicle model, this paper investigates the extent to which the PYS can be reduced using inertance-integrated primary lateral suspensions without increasing Root Mean Square (RMS) lateral carbody accelerations when running over a 5 km example track (with a number of vertical, lateral and longitudinal irregularities, and gauge variations). The vehicle, with inertance-integrated primary lateral suspensions, has been modelled in VAMPIRE (R), and the vehicle dynamics are captured over a range of different velocities and wheel-rail equivalent conicities. Several inertance-integrated suspensions are optimised, leading to permissible PYS reductions of up to 47% compared to the original vehicle, whilst lateral carbody accelerations remain at acceptable levels. This level of PYS reduction would result in a potential Network Rail Variable Usage Charge saving of 26%.