Determination of Material Parameters of Welded Tube via Digital Image Correlation and Reverse Engineering Technology

Material characteristics play an important role in tube hydroforming (THF). A method, based on digital image correlation (DIC) and reverse engineering (RE) technology, is proposed to determine the material parameters of a welded tube in hydroforming with a single tubular blank. The material parameters of the weld and parent metal are determined by applying membrane theory and the force equilibrium equations, as well as the deformation data which are obtained by DIC and RE technology in the THF process. Finite element simulations of welded THF are performed with these material parameters and the maximum bulge radii and axial profiles of the weld and parent the metal obtained from the simulations are compared with those obtained from the hydroforming experiments to verify the reliability of the proposed method. The results show that the material parameters of the weld are lower than those of the parent metal. With the material parameters adopted in FE simulation there is a good agreement between the simulation and the experiment as for the maximum bulge radii and axial profiles of the weld and parent metal. This verifies that the proposed method is acceptable for determining material parameters of a welded tube.