Prediction and Validation of Forming Limit Strains for Tube Hydroforming

Earlier work has demonstrated through simulations that the forming limit strains of tubes during hydroforming and sheets during stamping of identical mechanical properties show significant differences. Typically, the forming limit strains were higher during hydroforming. In the present work, the forming limit strains is predicted by considering expansion of tubes by hydroforming process under different boundary conditions, so as to generate drawing and stretching strain paths. The result were validated by carrying out tube expansion experiments on steel tubes and is found to be in agreement with simulation results. The effect of boundary condition on the evolution of microstructure is studied