RSSB - Inertance Integrated Trailing Arm Bush Design for Curving and Ride Quality

The research presented in this report investigates the potential application of inerters in the primary lateral suspension of a bogied passenger vehicle, in order to permit its primary yaw stiffness to be reduced whilst maintaining its dynamic behaviour to the same level as a base case vehicle with the original yaw stiffness. The purpose of this research is to improve curving performance and therefore reduce the track access charge (also called the Variable Usage Charge {VUC}) for the vehicle.

Simulations are carried it in the multi-body dynamics tool, VAMPIRE®. In order to ‘tune’ the suspension designs, including values of inertance, stiffness and damping, for the pre-defined inertance-integrated suspension layouts, and optimisation procedure is used. This co-optimisation is carried out using MATLAB®’s Optimisation Toolbox which calls VAMPIRE®, then runs a loop to carry out a Patternsearch optimisation and identify the best, or optimal, values for the suspension components that can achieve the biggest reduction in primary yaw stiffness whilst maintaining similar levels of RMS lateral acceleration (compared to the base case vehicle) of the vehicle when simulated over an example 5 km length of track. The optimisation is carried out for a range of vehicle speeds and contact conditions.

The optimisation results show that the primary yaw stiffness could be reduced by up to 47% with inertance-integrated layouts applied to the primary lateral suspension, whilst maintaining similar RMS lateral accelerations to the base case vehicle. This would result in a 26% reduction in Track Access Charge.

Project Funder: Railway Safety and Standards Board

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