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2
BEARINGS, BELTS & CHIAINS
Tests helped to make World Cup stadia vuvuzela-resistant
Long before the first kick-off at the recent football World
Cup in South Africa, engineers working for Wacker
Ingenieure Wind Engineering in Germany had tested
scale models of the stadia to determine how they would
handle storms, vibrations and other disturbances.
Using the three wind tunnels at their facility in
Birkenfeld, the engineers were able to test how the
stadia would withstand wind loads – and whether they
would start to vibrate when 80,000 fans celebrated
by making a deafening noise with their vuvuzelas.
The wind tunnels can generate wind speeds
of more than 100km/h to simulate the
conditions encountered during a hurricane.
The equipment uses scale models to
analyse structures such as skyscrapers,
airports or bridges, years before the
foundation stone is laid. The engineers
evaluate the test data using software
developed in-house. There is only one other
company in the world that offers similar "wind
engineering" services.
To obtain exact measurements, absolute precision is
required in the wind tunnels. For example, a rotary table
at the end of one of the tunnels carries scale models of
the building being tested, which can be turned through
360 degrees in 4,000 precise steps.
This table is rotated using a 3.2m-long, 30mm-wide belt
with protuberances known as nubs. The belt is attached
to a free-running steel rim, with the nubs facing
outwards and connecting with a drive wheel containing
matching indentations.
Bernd Reinhard of Wacker Aerodynamics (right) with René Pressler
from Hilger and Kern Antriebstechnik at the rotating table mounted
in front of the wind tunnel (background). The inset (left) shows a
close-up of the nubbed belt drive system. Photos: Wacker Ingenieure
“When combined with the nubbed wheel, the belt allows us to test aerodynamics in
precisely defined steps to obtain exact measurements,” explains Wacker’s
aerodynamics specialist, Bernd Reinhard. “The nubs on the nubbed wheel roll on a
precise circle. The constant belt tension and high performance are guaranteed by
wear-resistant, durable polyurethane with steel cord reinforcements.”
Wacker’s engineers developed the drive system in co-operation with Mulco partner
Hilger and Kern Antriebstechnik. The Synchrodrive N10 nubbed belt was supplied by
ContiTech’s Power Transmission Group.
The Wacker engineers are now using their wind tunnel equipment to test the stadia for
the 2012 European Cup in Poland.
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32 November/December 2010 www.drives.co.uk
www.renold.com