Identification of mechanical properties of the weld line by combining 3D digital image correlation with inverse modeling procedure

In this study, the 3D digital image correlation technique is combined with the inverse modeling methodology to determine mechanical properties of the weld line including heated-affected zone (HAZ). The literature showed that identification of detailed mechanical properties of the weld line is critical to the characterization of mechanical performance of such welded structures as tailor-welded blanks (TWBs). Typically, power law material constitutive model is adopted to simulate the elastoplastic response of the welded structures in finite element analysis, in which the two elastoplastic parameters, i.e., strain hardening exponent n and strength coefficient K, need to be determined in different weld zones, respectively. In this study, the strain hardening exponent is first determined by 3D digital image correlation (DIC) technique that has been widely used to measure strain experimentally. Then, the strength coefficient K is determined on the basis of the results obtained from the first step by using an inverse modeling technique. To validate the identified material parameters, the indentation tests are carried out in different welded zones and the load–depth curves are correlated to the corresponding modeling results, thereby demonstrating that the identification procedure of the mechanical properties is effective.