The levelized cost of electricity (LCOE) of wind energy has been declining in past decades. This is in large parts due to reduced manufacturing cost of wind turbines. However, to guarantee a further reduction in LCOE the requirement for servicing installed wind turbines should be reduced. As a key technology for tall, cost-effective towers bolted and welded connections must perform flawlessly. The loss of pre-tension in bolts has a tremendous impact on the performance wind turbines. It is therefore necessary to understand the underlying mechanism that lead to a loss of bolt pre-tension. 


The objective of this project is to identify the optimal monitoring for assessing the state of health of welded mechanical structures and loosening of bolted connections, e.g. loss of pretension in offshore turbines. 


The results of this project will allow to better forecast and also detect issues of bolt pretension loosening and weld health (crack detection/evolution).