Introduction  Wind energy is one type of rapidly-developing renewable clean energy. The number of installed wind turbines (WTs) has increased significantly over the past 20 years. The offshore WTs are typically exposed to a harsh sea environment and prone to natural hazards. Failure analyses for WTs are systematically reviewed in this paper.

  Method  The actual damage incidents during historical typhoons are summarized. Waves and earthquakes are another two types of potential hazards for offshore WTs that require serious consideration, although a limited number of WT structure failure induced by earthquakes was reported. A variety of load modeling and simulation methods, which are the prerequisite for WT structural failure analysis, have been developed for different types of loads.

  Result  Accordingly, different finite element methods, dynamic simulation methods, and failure criteria have been studied and adopted in the failure analysis. The past results obtained show that extreme wind load governs structural failure of WTs. Meanwhile, structural health monitoring (SHM) techniques have seen increasing applications in civil and mechanical structures. The state-of-the-practice for SHM in civil infrastructure is introduced. Similar SHM concept has recently been applied in WT industry.

  Conclusion  This review presents the principles and applications of SHM in WT. The valuable information derived from SHM systems can not only help to prevent potential structural failure, but also improve and optimize the current WT design. However, only a narrow range of WT SHM is covered in this paper. In-service long term monitoring for WT is a critical research area that needs significant research effort in future.