Experimental Study on Debonding Detection for Grouted Jacket Connection of an Off-Shore Wind Turbine Supporting Structure Specimen with PZT Patches

Abstract

Grouted jacket connections (GJCs) have been widely used to connect longitudinal components of offshore wind turbine supporting structures. Debonding defects detection in GJCs is critical for the safety and serviceability of offshore wind turbine support structures. In this paper, an interface debonding detection approach for a scaled GJC specimen using both surface stress wave and Electromechanical impedance (EMI) measurement is proposed with Piezoelectric lead zirconate titanate (PZT) patches. The scaled GJC specimen with various mimicked interface debonding detects is designed. Based on the surface stress wave measurements of PZT sensors arranged with a one pitch and multiple catch (OPMC) configuration, the regions of the mimicked defects are estimated using the intersections of the surface stress wave propagation paths with abnormal measurements. EMI measurements of PZT sensors located in the estimated debonding regions are used to accurately identify the dimension of the mimicked debonding defects using the root mean square deviation (RMSD) index of the impedance measurements of PZT sensors. The visualized debonding region is close to the actual location of the mimicked debonding defect.