Mechanical Properties Identification of Sheet Metals by 2D-Digital Image Correlation Method

Digital Image Correlation (DIC) method is a powerful technique for measuring material deformation field. By comparison of digital images of the undeformed and deformed configuration, DIC provides full-field displacements to sub-pixel accuracy and full-field strains in recorded images. Recently, the DIC method has been developed and used increasingly in various researches because of its advantages. However, a commercial 2D-DIC system requires a high initial investment. In this study, an in-house 2D-DIC system is developed to measure Young's modulus, Poisson's ratio, anisotropic plastic ratio parameters and flow curve under uniaxial tension of AL5052-O and high strength steel (DP980) sheets in rolling direction. The measured 2D-DIC results were compared with those of standard test method using strain-gauge type extensometer. The good agreement between the two measurement methods verifies the accuracy of the established 2D-DIC system. Furthermore, this method has been utilized in order to observe Portevin-Le Chatelier (PLC) band behaviour, Lüders band behaviour and shear band behaviour during tensile deformation of materials. The results of DIC method revealed reasonable results in measuring strain and local strain to capture ductile fracture behaviour of materials.