Experimental Survey of Temperature and Pressure of Hydroforming on Wrinkling Shape

Under the influence of coupled internal pressure and axial stress in tube hydroforming with axial feeding, wrinkles often occur and affect the forming results. Wrinkling behavior of an AZ31B magnesium alloy tube was experimentally investigated with different loading paths at different temperatures. Features of wrinkles, including shape, radius and width, were acquired from the experiments, as well as the thickness distribution. Numerical simulations were carried out to reveal the stress state during warm hydroforming, and then the strain history of material at the top and bottom of the wrinkles were analyzed according to the stress tracks and yielding ellipse. Finally, effects of loading paths on expansion ratio limit of warm hydroforming were analyzed. It is verified that at a certain temperature, expansion ratio limit can be increased obviously by applying a proper loading path and realizing enough axial feeding.

Keywords:

Tube hydroforming , Numerical simulations , Loading paths , Expansion ratio