Localization of defects in wind turbine blades and defect depth estimation using infrared thermography

摘要

Localization of defects and determination of the depth and size using Infrared Thermography is a critical problemin wind turbine blades. Infrared Thermography offers significant advantages over other Nondestructive Testingmodalities due to fast, wide-area inspection capabilities. Lock-in Thermography is an ideal method for defectdetection due to the presence of deep-lying defects in wind turbine blades, which otherwise go undetected.Multivariate Outlier Analysis is used in conjunction with Lock-in technique to enhance the detectability of thedefect. Results are presented on defects present in a 9m CX-100 wind turbine blade that was designed bythe Sandia National Laboratory. A defect depth estimation technique based on Pulsed Thermography is alsopresented. A 3D depth estimation model is presented which aims to address the shortcomings of the classicaldepth estimation methods that are primarily based on the 1D heat conduction equation. Results are presentedon a stainless steel sample with flat-bottom defects at known depths. The results are in excellent agreement withthe proposed theory.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.