Dynamic Wind Turbine Blade Inspection Using Micro-Polarisation Spatial Phase Shift Digital Shearography

Applied Sciences

Mohammad Osman Tokhi¹  Zhanfang Zhao¹  Zhiyao Li¹  Haitao Zheng²  Ryan Marks² 

[1] School of Engineering, London South Bank University, 103 Borough Road, London SE1 0AA, UK;TWI LTD, Granta Park, Great Abington, Cambridge CB21 6AL, UK;

关键词: digital shearography;    spatial phase shift;    temporal phase shift;    non-destructive testing;    wind turbine blade;   

DOI  :  10.3390/app112210700

来源: DOAJ

【 摘 要 】

Shearography, as a novel non-destructive evaluation technique, has shown notable ability in the detection of composite materials. However, in current shearography practices, the phase shifting and loading methods applied are mainly static. For instance, vacuum hood or force loading facilities are often used in phase-shifting shearography, and these are hard to realise with robotic control, especially for on-board inspection. In this study, a dynamic process for detecting defects in the subsurface of a wind turbine blade (WTB) using spatial phase shift with dynamic thermal loading was proposed. The WTB sample underwent a dynamic thermal loading operation, and its status is captured by a Michelson interferometric-based spatial phase shift digital shearography system using a pixelated micro-polarisation array sensor. The captured images were analysed in a 2D frequency domain and low-pass filtered for phase map acquisition. The initial phase maps underwent a window Fourier filtering process and were integrated to produce a video sequence for realisation of visualising the first derivative of the displacement in the process of thermal loading. The approach was tested in experimental settings and the results obtained were presented and discussed. A comparative assessment of the approach with shearography fringe pattern analysis and temporal phase shift technique is also presented and discussed.

【 授权许可】

Unknown