INTERNATIONAL: ‘We cannot ignore the management of the interface’, insisted Semih Kalay of TTCI. Addressing delegates at the Contact Mechanics 2009 conference in Firenze, he pointed out that a better understanding of the complex forces at play in the contact patch between wheel and rail translated directly into maintenance and renewal costs, which for larger railways could amount to ‘very substantial sums’.
Hosted by Prof Andrea Bracciali from the University of Firenze, the eighth International Conference on Wheel/Rail Interaction attracted more than 230 delegates from 27 countries, with 149 papers presented over three full days. Academics, suppliers and operators from across the rail sector came together to share their work and discuss their findings. Topics for the 30 parallel sessions ranged from wheel profiles and rail wear through contact forces and friction management to adhesion, noise and environmental impact.
As chairman of the international committee, Peter Mutton from Australia’s Monash University pointed out that the many past papers represented ‘a huge body of work’ which showed ‘just how much has been learned since 1982’. With this in mind, he explained, the focus has expanded from current research to consider industry challenges which could shape the need for future research work.
Emphasising this need for closer links between research and application, Roger Enblom of Stockholm’s KTH pointed out that ‘we are living in a market environment’, which had led — in his case — to expectations for increased performance of wheels, with a particular focus on the cost of maintenance and renewals. Thus KTH is working closely with Bombardier’s Västerås plant to try and predict future patterns of wheel wear. Enblom pointed to the challenges posed by interoperability, where railways had adopted different rail and wheel profiles, and the introduction by infrastructure managers of differential access charges dependent upon the track forces imposed by different vehicle types.
Making the case for condition-based maintenance, Daniel Magnus of US-based KLD Labs also emphasised the need to ‘treat the wheel and rail as a unit’, using as an example an investigation into flange-climbing derailments caused by the operation on the same route of two vehicle types with different wheel profiles.
Rolling contact fatigue continues to drive research into wheel and rail steels, preventive grinding and other maintenance strategies, as well as fundamental research to improve understanding of the mechanisms which initiate and propagate cracks. Many of these areas are being addressed in the EU-funded Innotrack research programme, which is due to conclude at the end of this year.
Meanwhile, new phenomena continue to emerge, and Stuart Grassie highlighted the recent appearance of ‘STUDs’ — or Squat-Type Unidentified Defects. These look similar to squats on the railhead, but occur in different places and do not seem to propagate in the same way, he suggested. Failure to identify correctly between potentially harmless and dangerous defects could pose a safety risk on the one hand or unnecessary increases in maintenance costs on the other, he warned, urging the need for further investigation.
The next CM conference is to be hosted by Southwest Jiaotong University of Chengdu in September 2012.