A fast lock-in infrared thermography implementation to detect defects in composite structures like wind turbine blades

Abstract

Effective AE source location of damages in the wind turbine blade AIP Conf.ABSTRACT. Delaminations are a common type of defect that occurs in composite structures like wind turbine blades. In this study, a Nondestructive Testing technique based on Fast Lock-In thermography is proposed to detect delaminations present in a 9m CX-100 wind turbine blade. A set of image processing algorithms and Multivariate Outlier Analysis were used in conjunction with the Fast Lock-In thermography technique to counter the 'blind frequency' effects and to improve the defect contrast. Receiver Operating Characteristic curves was used to quantify the gains obtained by using Multivariate Outlier Analysis. Experiments were performed on a set of sixteen defects of various sizes that were incorporated during the construction of the CX-100 wind turbine blade.

The Impact of Excitation Periods on the Outcome of Lock-In Thermography

“…Lock-in thermography is a popular type of non-destructive testing that uses an external source to induce temperature changes in a material or component, and then uses an infrared camera to measure the resulting thermal response. Lock-in thermography is often used to inspect composite materials such as aerospace structural elements [ 1 , 2 , 3 , 4 , 5 ], wind turbine blade parts [ 6 , 7 , 8 ], and other advanced composites such as composites containing nanotubes [ 9 , 10 ] as well as sandwich structures [ 11 ]. Lock-in thermography is widely used for detecting subsurface defects, such as cracks [ 12 , 13 ], delamination [ 14 , 15 , 16 ], impact damage [ 17 , 18 ], and corrosion [ 19 , 20 ].…”