(15/02/23 → 15/08/24)

Funded by Railway Safety and Standards Board, and Network Rail

Details on RSSB website

Rail surface damage caused by wheel-rail contact forces on curves makes a significant contribution to the overall cost of maintenance. Previous research has shown that passive suspension components can reduce track damage through better dynamic performance of railway vehicles, but at the cost of reduced stability and a loss of passenger comfort. 

RSSB and Network Rail are jointly funding a project to build and test a novel suspension component – a prototype enhanced trailing arm bush. There are hopes that the revised design can deliver strong dynamic performance while maintaining stability and ride quality. Early research estimated that the proposed optimised hydraulic bush design could save up to 40 per cent of variable track maintenance costs and 35 per cent of wheelset renewal, maintenance, and inspection costs. 

The work is being carried out by a consortium, led by the University of Bristol and supported by the Universities of Cambridge and Huddersfield, leading bushing supplier GMT, and experts from CAF, Hitachi, Alstom, and Eversholt. They will construct a prototype trailing arm bush device and experimentally demonstrate its performance.

Project Partners

(01/01/22 → 31/12/24)

Funded by Network Rail

Unsatisfactory Pantograph-Overhead Line (OHL) contact dynamics is a critical factor for the extremely high railway maintenance and electrification cost in the UK (Network Rail spending £4.2bn/year on maintenance/renewal its network and about £4m/km on route electrification). The project team will develop novel pantograph systems with transformed dynamic performance. The improvements will lead to reduced operational wear and relaxed Overhead Line specification, contributing to more sustainable railway assets and the UK net-zero mobility agenda. 

Project Partner

(01/07/19 → 31/05/20)

Funded by Railway Safety and Standards Board

Details on RSSB Website 

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 Partners

(01/02/19 → 01/06/19)

Funded by EPSRC Impact Acceleration Account

Pantograph-Catenary systems are the governing factor for railway vehicles’ current collection quality. Traditional dampers cannot effectively suppress contact force oscillations, leading to excessive infrastructure wear, poor energy collection and travelling speed limitations.

 This project has: 1) shown a 40%+ improvement on the pantograph-catenary interaction dynamics, 2) successfully developed the Bristol Pantograph-Catenary Testing Bed for next step testing and verification.

Project Partner

(01/02/18 → 01/06/18)

Funded by EPSRC Impact Acceleration Award

Offshore wind turbines (OWTs) are subjected to external loading from variety of sources such as wind and waves, which are rapidly changing in their characteristics and directions. With OWTs becoming taller, slenderer, and moving to deeper waters, excessive vibrations significantly reduce the OWT efficiency of converting wind energy to electricity and also the OWT structure’s fatigue life. This EPSRC IAA project has successfully demonstrated the effectiveness of enhance the damping performance of OWT using inertance-integrated damping technology.

Project Partner

(01/05/17 → 28/05/19)

Funded by EPSRC First Grant

Details on EPSRC Website

Mitigating unwanted vibration in mechanical structures via effective and reliable approaches is an important and difficult part of the design process. For example, a good balance between ride comfort and handling for passenger vehicles, the need to build taller and more slender buildings while maintaining good dynamic performances under wind and earthquake disturbances, and the trade off between maintaining straight running stability and reducing track wear when curving for railway vehicles, have all attracted much research from both academia and industry. In the current drive for more flexible, lightweight and more efficient structures, enhancing the capability of vibration suppression systems has become even more important.

The introduction of the inerter concept has from theoretical point of view fundamentally enhanced the capability of passive vibration suppression systems. Significant theoretical performance advantages for a wide range of mechanical structures have been identified. However, when working on real applications, we face the obstacle of inadequate knowledge of the dynamic properties of physical inerter realisations. This project will establish accurate fluid based inerter models and demonstrate the potential superiority of such designs for passenger cars, tall buildings and railway vehicles through case studies developed in close collaboration with industrial project partners.

The proposed work will enable the widespread uptake of fluid inerter based vibration suppression design techniques and constitute a major step towards wide spread application in multiple industrial sectors including road and rail transportation, civil engineering as well as aerospace engineering. The resulting improvements in the UK's capability for advanced design will greatly assist the high-end manufacturing industry to maintain its competitive edge.

Project Partners