Fiber bragg grating sensors and signal based detection method for failure detection of an offshore wind turbine grouted connection

A fatigue test has been conducted on a large scale offshore wind turbine grouted connection specimen at the Leibniz University of Hannover. For detecting the damage occurrence and severity into the grouted joint, a Structural Health Monitoring (SHM) system based on fiber optic sensors type Fiber Bragg Grating (FBG) has been implemented; and the features of the FBG signal responses have been then extracted using a time-frequency analysis called Wigner- Ville Distribution (WVD). Marginal properties of the WVD (such as the Energy Spectral Density) have also been investigated. The results show that the WVD can indicate the presence of structural damages in an efficient manner. This work is the first stage of investigations about the damage detection of offshore wind turbine grouted connections.