Load path optimization in tube hydroforming

The goal of this work was to identify the optimum combination of the main process parameters, i.e., the internal pressure and end feeding (load path), for tube hydroforming to minimize the thickness reduction, while satisfying the failure constraint defined by the forming limit diagram of the material. To perform process design optimization with minimum experimentation, the LS-OPT software was utilized in combination with a finite element model (FEM) that simulated a round to square tube hydroforming (THF) process for stainless steel 321 in LS-DYNA. The load path obtained through the optimization procedure was applied to the THF process and the tube expansion and the thickness results obtained from the FEM were compared with the experimental results in the critical regions of the hydroformed tube.