Research on the Effect of Thermal Coating Temperature on the Fatigue Performance of Wind Turbine Blade Bolts

Abstract

The bolted connection of wind turbine blades is a bridge for transmitting blade loads. In recent years, with the rapid increase in blade length, the fatigue load at the blade root has also been continuously increasing. The bolt fatigue strength has always been a bottleneck in the interface design between blade and wind turbine hub. However, industry standards still hold conservative values for the S/N curve of bolt fatigue, and there are unclear requirements for thermal coatings, The S/N curves provided by the standards in different periods do not meet the actual processing requirements of bolts. In order to study the effect of thermal coating temperature on the fatigue performance of threads and provide a reasonable basis for the subsequent design of long blade bolt connections. Based on the actual processing technology of bolts, experiments were conducted on the S/N fatigue curves of thermal coated bolts at different temperatures. The experimental results prove that the slope of the inclined part of the low-temperature Dacromet test data and the fatigue strength under 2 million cycles are significantly higher than normal temperature Dacromet coated bolts. Low temperature Dacromet can effectively improve the fatigue strength of bolts.