Year

2016

Degree Name

Doctor of Philosophy

Department

School of Mechanical, Materials and Mechatronic Engineering

Abstract

With the popularisation and rapid development of railway transportation, how to maintain train stability and reduce unwanted vibration to make the ride more comfortable has become an emerging research topic. This is why this project has included magnetorheological (MR) technology into railway vehicles to improve their performance.

Critical speed is an index and a key technology that directly indicates train stability, which is why the critical speeds of trains are calculated and analysed based on the dynamic equations of railway vehicles. These analyses revealed that secondary lateral damping and primary longitudinal stiffness are the most sensitive suspension parameters influencing critical speeds. In an attempt to improve dynamic performance, the secondary lateral dampers were replaced with conventional magnetorheological fluid (MRF) dampers; with the simulation and experimental results indicating that the semi-active suspension installed with MR dampers raised the critical speed and achieved a higher level of stability. The primary longitudinal stiffness is meant to be stiff when a train is running straight to maintain the stability and then soft when the train is turning, for better trafficability. To solve this dilemma, an innovative magnetorheological elastomer (MRE) based primary longitudinal rubber joint with variable stiffness characteristics has been developed. The simulation shows that controlling the MRE joint when a train runs on straight and curved track can satisfy these apparently conflicting requirements and realise good trafficability on curved track and high stability on straight track.

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