RSSB - Enhanced Trailing Arm Bush Design for Rail Surface Damage Reduction

This project focused on the optimisation and physical design of a primary suspension component, i.e. the trailing arm bush, with the aim to minimise the primary yaw stiffness (PYS) without compromising the ride quality. A typical high-speed passenger railway vehicle, Mark 4 Coach, has been adopted for this study. Compared with the Hall Bush used on the Mark 4 Coach, the proposed design will further improve the curving behaviour and therefore further reduce the track access charge.

In this project, systematic optimisations on primary lateral and longitudinal suspensions (separately) have been carried out using a co-simulation between VAMPIRE and MATLAB. The project team has obtained an optimum longitudinal suspension network with zero longitudinal static stiffness, allowing a 97% PYS reduction. A significantly lower Tγ in curves could be achieved with this new solution compared with the default suspension and the HALL Bush case. All the assessed performances, such as ride comfort, stability and curving, have been found to be satisfactory, apart from the increased suspension deflection for tight curves.

This project team has proposed a framework for integrated rubber-hydraulic bush design, which can systematically realise beneficial network-represented properties with the tailored stiffness, damping and inertance, satisfying specific physical design constraints. In this project, integrated rubber-hydraulic designs have been developed to realise the optimised networks. Specifically, a physical design with 1.6MN/m longitudinal static stiffness (Mark 4 Coach Hall bush’s longitudinal stiffness: 3.9MN/m) has been successfully developed. This design has the identical size as the Hall Bush and satisfies all performance and physical design requirements (including the stroke requirement). Using nonlinear network-based model in Vampire, this proposed design with 1.6MN/m longitudinal stiffness has shown a 39% Variable Usages Charge (VUC) reduction with a simulation-based performance verification. This is significantly larger than the 27% VUC reduction achieved by the HALL Bush for Mark 4 coaches.

A note on the developed physical designs: Due to confidentiality, the detailed physical designs of enhanced trailing arm bush have been included in a separate document, ‘Railway inerter designs’. To access this document, please get in touch with RSSB for a relevant procedure to be sorted out.

Project Funder: Railway Safety and Standards Board

Project Partners:
Railway Safety and Standards Board (RSSB), Siemens, Network Rail, University of Cambridge, University of Huddersfield