Fatigue Failure Accident of Wind Turbine Tower in Taikoyama Wind Farm

摘要

One of the wind turbine nacelles at Taikoyama wind farm collapsed due to the fatigue failure of high tension bolts. Strain gauges and accelerometers were installed on the wind turbine to verify the aerodynamic model. Furthermore a FEM model was built in order to find out the relationship between tower tube and high tension bolts at the position of flange joint, where the fracture occurred. When the bolt's pre-tension force decreases, its stress range increases. Less the pretension force left, the larger the stress range will be. Hence when pre-tension force is 0%, the fatigue life is left for only a few days. On the other hand when 17 bolts are damaged, the turbine tube stress is three times larger than the stress when all the bolts are in good condition. Hence the fatigue evaluation shows that the life time rapidly decreases to less than two months compared with that of the normal life time which is 20 years.