Topology optimization of a 500kW wind turbine main load frame

As wind turbines get larger and larger, nacelle weight becomes more important as it affects cost, logistics and even turbine natural frequencies. This work presents a nacelle weight optimization process for a main load frame of a 500 kW wind turbine. While the weight is minimized structural strength has been preserved. In order to achieve an effective weight reduction, topology optimization methodology is used with the aid of finite element solvers like OPTISTRUCT. Combined wind, generator and gravity loading condition have been considered while stress analyses are conducted. The work started with an initial over safe 7000 kg design. Through topology optimization iterations 28.57 % weight reduction has been achieved. Using SIMP method, weight reduction or material removal locations were carefully identified. The redesigned nacelle main frame has maximum stress levels less than 40% of the material yield strength.