Microwave imaging for delamination detection in T-joints of wind turbine composite blades

Wind turbines play an increasingly important role in renewable power generation. The structural health monitoring could better improve the maintenance and operation of the wind turbine blades in the field. In this paper, delamination in glass fibre composite joints of a wind turbine blade is successfully detected using the non-contact microwave imaging technique with an open-ended waveguide. The existence and extent of the delaminated region are identified from the produced scan images. In addition, the variation of skin/flange thickness, the presence of the web underneath the skin and manufacturing induced defects can also be distinguished. The phase profiling provided by the scanning shows higher sensitivity to the presence of delamination than the magnitude profiling. The optimum inspection frequency range is investigated, which offers a reference for future applications.