Remote Inspection of Internal Delamination in Wind Turbine Blades using Continuous Line Laser Scanning Thermography

This study proposes a continuous line laser scanning thermography (CLLST) system for remote inspection of internal delamination in wind turbine blades. The CLLST system offers the following advantages: (1) remote delamination inspection can be achieved by mechanically scanning a line laser beam and simultaneously capturing the corresponding thermal waves in nondestructive and noncontact manners; (2) internal delamination and surface damages can be classified by analyzing laser-induced thermal wave propagating patterns; (3) instantaneous delamination detection and quantification can be accomplished without using baseline data which is previously collected from the pristine condition of a target blade. To examine the feasibility of the CLLST system, laboratory and full-scale tests were performed using a carbon fiber reinforced polymer (CFRP) plate, a 10 kW glass fiber reinforced polymer (GFRP) wind turbine blade, and a 3 MW GFRP wind turbine blade. The test results demonstrated that the 10 mm diameter internal delamination located 1 mm underneath the blade surface was successfully detected even 10 m far from the target blade with a laser scanning speed of 2 mm/s.