Detection of defects in wind turbine composite blades using statistically enhanced Lock-In Thermography

Abstract

Delaminations are a common type of defect that occurs in composite structures such as wind turbine blades. In this study, a nondestructive testing technique based on Lock-In Thermography is proposed to detect skin-skin delaminations and skin-core delaminations present in a 9-m CX-100 wind turbine blade. A set of image processing algorithms and multivariate outlier analysis were used in conjunction with the classical Lock-In Thermography technique to counter the ''blind frequency'' effects and to improve the defect contrast. Receiver operating characteristic curves were used to quantify the gains obtained by using multivariate outlier analysis. Experiments were performed on a set of 16 defects of various sizes that were incorporated during the construction of the CX-100 wind turbine blade at different locations and depths.

Outlier analysis of nonlinear solitary waves for health monitoring applications

“…The framework of OA is available in classical statistical textbooks 20,21 while its first application to diagnose structural damage is attributed to Worden 22 who detected the reduced stiffness of a simulated lumpedmass system using the dynamic transmissibility function associated with vibration-related data. Despite the vast literature on OA applied to vibration data, [22][23][24][25][26][27][28] infrared images, 29 electromechanical impedance signatures, 30,31 and guided ultrasonic waves, [32][33][34][35][36][37][38][39] and the recent studies about the application of HNSWs for SHM and NDE, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] there are no scientific studies about the use of unsupervised learning algorithms to process solitary waves data. The work presented in this article aims at filling this lack of knowledge by proposing a new monitoring paradigm that can be divided into three steps.…”

Measurement of quality test of aerodynamic profiles in wind turbine blades using laser triangulation technique

“…[1][2][3][4][5][6][7][8][9][10][11] Some of these techniques uses coordinate machine measurements (CMM), 1 which is the most common and reliable measurement method of profile measurement of blades. In order to achieve maximum efficiency some shapes, dimensions and aerodynamic profiles are required for blades so manufacturing process of these parts requires quality inspection techniques.…”

“…Several authors describe different techniques that have been implemented for aerodynamic profiles measurements of wind turbine blades. [1][2][3][4][5][6][7][8][9][10][11] Some of these techniques uses coordinate machine measurements (CMM), 1 which is the most common and reliable measurement method of profile measurement of blades. This is the method with the highest measurement accuracy nowadays and has the advantage of completing precision measurement of the profile with complex structure.…”

Electrical self-sensing of impact damage in multiscale hierarchical composites with tailored location of carbon nanotube networks

“…When the source of impact delivers enough energy, FRPCs may experience complex failure modes driven by a combination of matrix cracking, fiber breakage, delamination, and fiber/matrix interfacial failure, compromising the integrity of the composite. [2][3][4] To date, several structural health monitoring (SHM) techniques exist for examining the structural integrity of composite materials, such as thermography, 5,6 X-ray microtomography, 7 ultrasound, 8 and acoustic emissions. 9,10 However, in many cases, their implementation for in situ real-time monitoring is complicated, since such techniques are susceptible to external noise, or require voluminous and expensive equipment.…”