German engineers are helping to design a 2014 Winter Olympics bobsled run using a new track simulator.
Researchers at the Fraunhofer Institute for Mechanics of Materials (IWM) have created a 3.8m-high wheel-shaped rig that can be used to measure the levels of friction between a bobsled and the particular type of ice that will be used to build a new track.
Test runners representing those on the bottom of a bobsled are placed on a layer of ice inside the wheel, which is then spun at up to 150kph (93mph) to simulate the movement of a sled down a run.
By recreating the environmental conditions of the location where the track will be situated, including ice created with water from the site, researchers can provide data to help design the track for maximum speed within safety limits.
‘When they design the track too slow, it’s boring; when it’s too fast they could kill someone,’ Prof Matthias Scherge, business unit manager at the IWM, told The Engineer.
The rig, which is being used to design the track for the 2014 Olympic Winter Games in Sochi, Russia, replaces much smaller lab-based equipment that doesn’t provide as accurate data and only operates at speeds of several kilometres an hour.
‘With this set-up we are able to measure at the real and adequate high-speed range, whereas before most people tried with low speeds,’ said Scherge. ‘Now we can complete this with a high-speed approach to round up the data.’
The new equipment uses force sensors to measure the load applied to the runners and the sliding velocity, and calculate a value called the coefficient of frictions, which can then be fed into a computer simulation for track designers.
‘They use these data sets to improve the design of the track in terms of speed and radius of the curves and the like,’ said Scherge.
‘We have learnt that according to the treatment of the runners by the team and the quality of the icemaking at the location and the environmental conditions there are huge differences. The coefficient of friction can change between a factor of 10 and 100 and this is huge.’
The IWM team tested the equipment in spring 2011 following one year of design and building work in collaboration with prominent bobsled German track designer Udo Gurgel.
Scherge said the biggest challenge was removing background ‘noise’ from the data, for example, from tiny bumps in the track, by using dampeners, avoiding resonance frequencies from the equipment itself and by filtering the data set.
‘For an extremely low coefficient of friction you have to measure low forces and when you have a lot of noise you don’t see the signal anymore,’ he added.