Optimal Vibration-Absorber Design: A case Study on Railway Trailing Arm Bush

The wheel-rail surface damage in curves can be effectively reduced with a lower Primary Yaw Stiffness (PYS), while a lower PYS would compromise the passenger comfort with conventional trailing arm bushes (a type of railway vehicle primary suspension component). Previous studies showed that a hydraulic-damping-integrated trailing arm bush has the potential to combat the trade-off between surface damage and ride comfort. However, it only considered one specific parameter set (hence a specific PYS), while there are numerous design possibilities unexplored (e.g., considering multiple fluid passageways). Therefore, the maximum achievable PYS reduction by optimal trailing arm bush design is still unknown. To fully unlock the potential, this work applies an optimal vibration-absorber design methodology to design the trailing arm bush which can provide the minimum PYS without compromising ride comfort. This methodology enables a wide range of design possibilities to be systematically explored and the optimal design to be identified. The potential lifetime cost savings due to surface damage reduction caused by the optimal design have also been estimated. Considering a case study for a Mark 4 Coach, the results show that the optimal network-based bush solution can reduce PYS by 97% over the default without compromising the ride comfort. Two novel physical designs have been proposed accordingly to realise the optimal network properties, achieving up to £41 million saving in track and wheelset maintenance costs. Whilst this study has used the trailing arm bush and Mark 4 coach as an example, the vibration-absorber design methodology is directly applicable to other types of railway suspensions and vehicle types.