Measuring full-field deformation of hyperelastic material using digital image correlation

Abstract

Digital image correlation, an optics-based strain measuring technique, has gained popularity during the last decade. The practice of employing digital image correlation-based measuring techniques in experiments has progressed dramatically owing to many incorporated sophistications: ease of use, greater precision, extensive measurement range, and stability of the results. While cutting-edge DIC measurement systems are commercially available, their high capital costs make them unaffordable for widespread usage. Several studies on establishing DIC-based measurement techniques with experimental validation have been undertaken over the years. The majority of prior DIC research concentrated on the testing of concrete, masonry, and metal alloy specimens, and little effort was made in assessing materials with substantial elongations. This dissertation presents an innovative DIC-based measuring tool for capturing surface deformation information with better precision. The proposed system is composed of two commonly accessible digital cameras as well as MATLAB-based algorithms. Uniaxial tensile tests of latex specimens are used to demonstrate the aptness of the proposed approach in capturing substantial deformations, and displacement estimates are validated against Vernier Caliper readings. A secondary high-precision measuring tool, the Ncorr program, was used to validate the integrity of the results produced by this technique. According to the comparison of results, it is proven that the system is capable of producing precise full-field displacement and strain maps with an apparent accuracy greater than 96 %. Furthermore, the similarity of the contour plots obtained using the proposed approach and outcomes of the Ncorr program verified the reliability of the proposed technique.