Numerical Study of the Effect of Parameters Uncertainty in Free Tube Hydroforming Process

In the present work, we perform a numerical study that explore the influence of the variability of mechanical properties and process parameters on the prediction of the pole height evolution in tube hydroforming process. In order to carry out this study, a mild steel S235 was chosen as the reference material and the free tube hydroforming process was considered. The factors selected for this variability study were the coefficient of friction (μ), the anisotropy coefficients (R0°, R45°, R90°), the dies length (L) and the initial tube thickness (t0). The variability of all factors was described by a probabilistic normal distribution, with a well-defined mean and standard deviation. Different simulations were performed by varying the process parameters for each trial of the Box-Behnken table of the experimental design. This numerical study was followed by response surface modelling and graphical analysis. ANOVA was also performed to determine the significant parameters and their impact on the response. Finally, we can conclude that the factors (L) and (t0) have a clear effect on the height-pole response of the bulge zone.