Fatigue analysis approach of a 500kW wind turbine main load frame

As wind industry get larger and larger, maintenance of safety and reliability of the turbine equipment becomes more and more important. Main load frame is one of the most critical components of the turbine and should have a very reliable fatigue safety due to the component is used as a main load transmitter and main mount for all nacelle equipment. This work presents a fatigue life design process for a main load frame of a 500 kW wind turbine. While the cyclic life of the turbine is kept to be an infinite, both static safety factors and weight of the main load frame is preserved optimally. In order to achieve an effective fatigue design, modified Goodman fatigue theory is used with the aid of commercial finite element software. Dynamic strength of the materials and the safety factors of the bedplate is calculated analytically. The stress analyses are conducted with the finite element methodology. The stress oscillations are determined for the both parts of the hybrid bedplate. Values of the maximum and minimum stresses are calculated with the aid of the commercial finite element solver. Through the fatigue analysis iterations quite high fatigue safety factors are obtained with respect to commonly accepted standards´ fatigue safeties.