Determination of optimal loading profiles in warm hydroforming of lightweight materials

In this study, a methodology is developed to determine proper profiles of the hydraulic pressure and the blank holder force under warm hydroforming conditions at different punch speeds. First, finite element models (2-D and 3-D) are developed and validated through comparisons with the experimental results from the literature. To determine the optimal hydraulic pressure and blank holder force profiles simultaneously, an adaptive FE analysis with fuzzy control algorithm was developed. Thinning, wrinkling, punch wall contact, die corner floating and conduction were used as criteria in the fuzzy control algorithm. The effects of the determined loading profiles are then presented in terms of thickness, strain and stress, and temperature distributions as well as success/failure of the forming process. The effect of punch speed was also investigated to reveal its impact on part formability. It was found that the optimal process conditions can be rapidly and accurately obtained with the developed adaptive FEA method coupled with fuzzy control algorithm.