Improved 2D Digital Image Correlation Method for Displacement and Deflection Measurements of Structural Beams

Abstract

Digital imaging correlation (DIC) is an innovative approach for evaluating full-field mechanical deflections and time-dependent responses of structural members. An illustration of 2D DIC is shown for a rigid body translation of a small-scale steel beam. This paper presents improvements in deployment of 2D DIC for evaluating mechanical behaviors and responses of structural beam members. Improvement considerations regarding image resolution and speckle correlation design were emphasized for observing flexural behavior of steel and timber structural beams. A suggestive guideline for focal length configuration for observing displacements with 2D DIC and a contrasting speckle design emphasizing physical pixel sizing was presented. The DIC displacements were converted to physical scale measurements capturing within 1% error differences and subpixel accuracies when compared to traditional measuring devices and numerical modeling. DIC enabled detection of mid and full span deflection distribution in addition to time-dependent displacements advocating for DIC’s versatility for structural beam evaluations.