Study on fastening process of high strength blade root bolts of offshore wind turbine

The connection between the blade and hub of wind turbines relies on high-strength bolts, and any failure in these bolts can critically impact the safety and reliability of the turbines. Focusing on the high-strength blade root bolts of MW-class wind turbines, this paper begins by analyzing the failure mechanisms of these bolts. A meso-scale finite element model of the blade root bolts is established to examine the variation in pre-tightening force throughout the fastening process, specifically in relation to tension-based fastening methods. Additionally, a test system simulating the installed state of the bolts is constructed to investigate the influence of fastening process parameters on the pre-tightening force. The results indicate that step-by-step tensioning, bolt length, and the stiffness of the bolt interface significantly affect the accuracy of the pre-tightening force. Controlling the instantaneous attenuation of the pre-tightening force can effectively enhance fastening precision, thereby reducing the likelihood of bolt failure.