Surface stitching of a wind turbine blade using digital image correlation

Abstract

Advances in computing and camera technologies have greatly enhanced the utility of three dimensional (3D) digital image correlation (DIC) in the last several years. For example, 3D DIC is now being used as a tool to measure operational deflection shapes, full-field dynamic strain and discrete point tracking. Due to the line of sight requirements of stereo photogrammetry it may not be possible to measure every location required on a surface within a field of view allowed by a single camera pair. Therefore, there is a need to have the capability to stitch several fields of view together, providing a continuous measurement over the entire surface of a structure. This paper presents an approach to stitch several fields of view measured using 3D DIC, to provide full-field information of a Sandia National Laboratories CX-100 nine meter wind turbine blade. A loading test was performed on the cantilevered turbine blade with 16 separate fields of view captured in both loaded and unloaded conditions. The processed results provide full surface displacement and strain information of the CX-100 nine meter blade. These results indicate the potential of utilizing stitching to perform full surface static and dynamic measurement of structures. © The Society for Experimental Mechanics, Inc. 2012.