Windmills are subject to cyclic loading, which means even small cracks in the load-bearing structure can grow and eventually lead to catastrophic failure. One catastrophic failure occurred yesterday near the Central German town of Kirtorf, read here (in German). Hat-tip Dirk H.
The tower broke 25 meters up. Investigators are now examining the rubble to deterime the exact cause of the failure. Looking at the detailed photos at the above link, it looks as if the failure occurred where two tower segments are bolted together. Maybe cheap, counterfeit bolts were used. Luckily no one was injured or killed.
The mishap occurred at about 11:30 in the morning at a windpark with 7 turbines. The blades, turbine and upper part of the tower crashed onto a path on the ground, reaching as far as 50 meters away. The debris even struck and destroyed a nearby transformer station. Meanwhile officials have called for a shutdown of 17 other turbines in the area and that they be subjected to a thorough technical inpsection before being allowed to go online.
Other news reports say the turbine was erected 11 years ago and that the maximum windspeed recorded yesterday was 57 km(hr – stormy, but usually a wind speed that windmills have no problems coping with.
Reader Andreas Luft at the first link mentioned above wrote:
I also work on wind turbines. This type here must be a D-Wind system. But I’m familiar with onkly the D6 and D8. This could be a D4.
There are many problems with the towers also in Austria. They too also rust, and there is much corrsion damage at the welds of the steel plates. But I’ve never seen such a material fatigue before.
But the photos don’t show any signs of rust.