A method for overlapping two DIC views by using a two-tone speckle pattern

Abstract

Because both the accuracy and spatial resolution of digital image correlation (DIC) are directly related to the field-of-view and the number of pixels, it is sometimes advantageous to have a tight view for high resolution measurements and a wide view for overall object deformation. This approach will be demonstrated using a high-speed measurement of the deformation and strain of a riveted thin plate with an explosive loading. Overall plate deformation was provided by a wide-view stereo system, while a tight view of a section of the rivets was imaged with a second stereo pair to measure the strain around the rivet holes. The challenge is creating a speckle pattern which will work with both systems without creating holes in the overall measurement data. This was accomplished by creating a black/white course pattern for the wide view and a black/grey/white fine pattern for the tight view. The grey speckles were sized such that they are not resolved by the wide view and therefore do not compromise the full-field measurement. Details of the process and example results will be presented. © The Society for Experimental Mechanics, Inc. 2014.