Strong Wind Topples a Wind Turbine in Japan (digitaltrends.com)

An anonymous reader writes: Strong gusts brought by Typhoon Cimaron on Friday, August 24, toppled a massive wind turbine in western Japan, local media reported. The 60-meter-tall turbine was located in a park on Awaji Island, 275 miles west of Tokyo, but was wrenched from its base in the early hours of Friday morning as the typhoon pummeled a large part of the Japanese archipelago. Fortunately no one was under the wind turbine when it came down, or indeed on it. Built in 2002, the turbine had been out of commission since May last year after being struck by lightning, according to the Japan Times. News footage showed how the turbine had been torn from its base by the strong winds, with its 20-meter-long blades badly damaged by the impact with the ground. It's not yet clear if the base had been weakened in some way prior to the typhoon.

Comments

failure analysis

[albeit unknown]

I hope they perform a thorough metallurgical, materials, and design analysis of this failure.

You can see from the video the base of the tower is held onto the foundation with a ring of tension rods or rebar. This is where the failure occurred

Corrosion? Unexpected fatigue loads? Design error (including counting on active blade feathering in a storm for protection, not present since shut down) ? problems with the steel? (alloy composition, heat treatment process, hydrogen embrittlement)

Re:blade lock

[mrbester]

It's incorrect that newer models have this revolutionary (pun intended) "feathering", when the problems of too high a wind speed for safe operation have been known and dealt with for centuries by every country with windmills. You lock / brake and feather and hope for the best.

Jill windmill (Clayton Hill, Sussex) had similar issues in October 1987, when the hurricane force winds defeated the brake. Due to the sweeps being not of a kind that could be feathered (not that it would have made much difference anyway), they still turned causing massive friction against the brake and ultimately caused a fire that threatened to engulf the entire wooden structure. It wasn't easy to put that one out.