Assessment of Measuring Errors in Strain Fields Obtained via DIC on Planar Sheet Metal Specimens with a Non-Perpendicular Camera Alignment

• Published in: Applied Mechanics and Materials Vol. 70; pp. 165 - 170
• Main Authors: Coppieters, Sam, van Houtte, Paul, Debruyne, Dimitri, Wang, Yue Qi, Lava, Pascal
• Format: Journal Article
• Language: English
• Published: Zurich Trans Tech Publications Ltd 18.08.2011
• Subjects: Stereo Vision; Finite Element (FE) Simulation; Digital Image Correlation (DIC); Strain Calculations; Systematic Errors
• ISBN: 303785202X; 9783037852026
• ISSN: 1660-9336; 1662-7482; 1662-7482
• DOI: 10.4028/www.scientific.net/AMM.70.165

The determination of strain fields based on displacement components obtained via 2D-DIC is subject to several errors that originate from various sources. In this contribution, we study the impact of a non-perpendicular camera alignment to a planar sheet metal specimen’s surface subject to biaxial loading conditions. The errors are estimated in a numerical experiment. To this purpose, deformed images - that were obtained by imposing finite element (FE) displacement fields on an undeformed image - are numerically rotated for various Euler angles. It is shown that a 3D-DIC stereo configuration induces a substantial compensation for the introduced image-plane displacement gradients. However, higher strain accuracy and precision are obtained - up to the level of a perfect perpendicular alignment - in a proposed ”rectified” 2D-DIC setup. This compensating technique gains benefit from both 2D-DIC (single camera view, basic amount of correlation runs, no cross-camera matching nor triangulation) and 3D-DIC (oblique angle compensation).