Funding:

• • Von Leibig Foundation

  • National Science Foundation

Purpose:

To detect and quantify defects in wind turbine composite blades using enhanced Infrared Thermography.

Synopsis:

A recent report from the American Wind Energy Association ranks Wind as the primary source of Renewable Energy in the U.S. The Department of Energy has set the target of wind producing 20% of the U.S. electric supply by 2030. Wind turbine blades are primarily composite structures. The presence of structural defects (introduced during the manufacturing process or developed in service) severely affects performance and strength of the blades and reduces the cost effectiveness of the system.

Enhancements to the Infrared Thermography technique are being made to detect and quantify the flaws in the blades. Such enhancements consist of (a) quantitative, 3-D thermal diffusion models for isotropic and anisotropic materials to relate an internal defect to the surface temperature profile, (b) statistical analysis of the infrared images to increase defect contrast and minimize false positives, and (3) optimization of the lock-in thermography technique to penetrate the thick skin of the blades.

Experiments are being conducted on a 9m CX-100 wind turbine blade that is housed in the Powell labs. The CX-100 research blade was fabricated by TPI composites in collaboration with Sandia National Labs. The blade contains over 45 documented defects of different sizes and types that are commonly encountered in real-world scenario.

Selected Publications:

Manohar, A. and Lanza di Scalea, F., “Wavelet-aided Multivariate Outlier Analysis to Enhance Defect Contrast in Thermal Images,” Experimental Techniques, 38(1), pp. 28-37, 2014.

Manohar, A. and Lanza di Scalea, F., “Detection of Defects In Wind Turbine Composite Blades Using Statistically-Enhanced Lock-In Thermography,” Structural Health Monitoring International Journal, Special Issue on Noncontact Measurement Technologies, 12(5-6), pp. 566-574, 2014.

Manohar, A. and Lanza di Scalea, F., “Modeling 3-D Heat Flow Interaction with Defects in Composite Materials for Infrared Thermography,” NDT&E International Journal, 66, pp. 1-7, 2014.

Manohar A. and Lanza di Scalea, F., “Determination of Defect Depth and Size Using Virtual Heat Sources in Pulsed Infrared Thermography,” Experimental Mechanics, 53(4), pp. 661-671, 2013.

Manohar, A. and Lanza di Scalea, F., “Modeling Heat Flow Interaction With Defects In Composite Materials Using Virtual Heat Sources In Pulsed Thermography,” Proceedings of the 2013 ASME International Mechanical Engineering Congress and Exposition (IMECE 2013), San Diego, CA, November 15-21, 2013.

Manohar, A. and Lanza di Scalea, F., “Defect Detection and Size Estimation in Composite Materials Using Infrared Thermography,” Proceedings of the SEM 2013 Annual Conference & Exposition on Experimental and Applied Mechanics, Lombard, IL, June 3-5, 2013.

Manohar, A., Tippmann, J., and Lanza di Scalea, F., “Localization Of Defects In Wind Turbine Blades And Depth Estimation Using Infrared Thermography,” Proceedings of SPIE (International Society for Optical Engineering) Smart Structures/NDE Annual International Symposium – Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems, M. Tomizuka, ed., San Diego, CA, March 11-15, Vol. 8345, 2012.

Tippmann, J., Manohar, A., and Lanza di Scalea, F., “Wind Turbine Blade Inspection Tests At UCSD”, Proceedings of SPIE (International Society for Optical Engineering) Smart Structures/NDE Annual International Symposium – Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems, M. Tomizuka, ed., San Diego, CA, March 11-15, Vol. 8345, 2012.