Digital Image Correlation (DIC) system as a verification tool for constitutive models of deformation with complex strain path changes

Abstract

experimental studies in the light of deformation inhomogeneities. Modern multiphase steels were used as their mechanical properties are very sensitive and strictly dependent on the combination of microstructure components with different levels of their mechanical responses. DIC as a precision tool has been used to investigate the deformation inhomogeneity during the tensile tests of specimens previously deformed with complex strain path history. The study was focused on the combined metal forming processes (i.e. Accumulated Angular Drawing (AAD), Wire Drawing (WD) and Wire Flattening (WF)). These processes are characterised by a combination of various deformation mechanisms (area reduction, torsion, bending, burnishing), and thus, are strongly affected by nonlinear strain path changes. Then, data provided in the experimental part of the work was used to assess the existing work hardening models in the light of their applicability for the prediction of mechanical response of materials subjected to nonlinear loading conditions. In the numerical analysis, work hardening model (i.e. Chaboche model) was investigated. The results of computer simulation were then compared with the DIC measurements and conclusions regarding applicability of the proposed approach were drawn. The comparison of the DIC data processing with tensile test data shows that correlation techniques provide results sufficiently accurate to study the inception and the evolution of the strain localization phenomena, so this methodology could be successfully applied in a more complex, as in the present investigation, forming problems.